Mulberry latex rich in antidiabetic sugar-mimic alkaloids forces dieting on caterpillars

Protein engineering of transaminase facilitating enzyme cascade reaction for the biosynthesis of azasugars

Azasugars, such as 1-deoxynojirimycin (1-DNJ), exhibit unique physiological functions and hold promising applications in medicine and health fields. However, the biosynthesis of 1-DNJ is hindered by the low activity and thermostability of the transaminase. In this study, the transaminase from Mycobacterium vanbaalenii (MvTA) with activity toward d-fructose was engineered through semi-rational design and high-throughput screening method. The final mutant M9-1 demonstrated a remarkable 31.2-fold increase in specific activity and an impressive 200-fold improvement in thermostability compared to the wild-type enzyme. Molecular dynamics (MD) simulations revealed that the mutation sites of H69R and K145R in M9-1 played crucial roles in the binding of the amino acceptor and donor, leading to the stable conformation of substrates within the active pocket. An enzyme cascade reaction was developed using M9-1 and the dehydrogenase from Paenibacillus polymyxa (GutB1) for the production of mannojirimycin (MJ), which provided a new idea for the in vitro biosynthesis of 1-DNJ.

Characterization, Antioxidant, and Antimicrobial Properties of Mulberry Lattices

In order to find the most advantageous bioactive compounds from mulberry latex for drug development in the near future, this study was conducted to characterize and evaluate antioxidant and antimicrobial properties from four different mulberry lattices (BR-2, S-1, AR-14, and S-146). The characterization of the lattices was performed by scanning electron microscopy with energy-dispersive X-ray spectroscopy, gas chromatography coupled to mass spectroscopy, and Fourier transform infrared spectroscopy. Further, screenings of the antioxidant and antimicrobial potential of selected lattices were performed in vitro using 2,2-diphenyl-1-picrylhydrazyl assay and agar well diffusion methods, respectively. Interestingly, the outcome of the current study revealed that tested mulberry lattices contain a considerable amount of bioactive phytoconstituents, particularly antimicrobial and antioxidant compounds, as revealed by chromatographic analysis. BR-2 latex was found to have significant antioxidant activity (75%) followed by S-146 (64.6%) and AR-14 (52.9%). The maximum antimicrobial activity was found in BR-2 latex compared to other tested latex varieties. The results of this investigation showed that mulberry latex from the BR-2 type may successfully control both bacterial and fungal infections, with the added benefit of having enhanced antioxidant capabilities.

Norsesquiterpenes from the Latex of Euphorbia dentata and Their Chemical Defense Mechanisms against Helicoverpa armigera

Euphorbia dentata (Euphorbiaceae), an invasive weed, is rarely eaten by herbivorous insects and could secrete a large amount of white latex, causing a serious threat to local natural vegetation, agricultural production and human health. In order to prevent this plant from causing more negative effects on humans, it is necessary to understand and utilize the chemical relationships between the latex of E. dentata and herbivorous insects. In this study, three new norsesquiterpenes (1-3), together with seven known analogues (4-10), were isolated and identified from the latex of E. dentata. All norsesquiterpenes (1-10) showed antifeedant and growth-inhibitory effects on H. armigera with varying levels, especially compounds 1 and 2. In addition, the action mechanisms of active compounds (1-3) were revealed by detoxifying enzyme (AchE, CarE, GST and MFO) activities and corresponding molecular docking analyses. Our findings provide a new idea for the development and utilization of the latex of E. dentata, as well as a potential application of norsesquiterpenes in botanical insecticides.

BmTBP upregulates the transcription of BmSuc1 in silkworm (Bombyx mori) by binding to BmTfΙΙA-S

The BmSuc1 gene, which encodes a novel animal-type β-fructofuranosidase (EC 3.2.1.26), was first cloned and identified in silkworm (Bombyx mori). As an essential sucrase, the activity of BmSUC1 is unaffected by alkaloidal sugar mimics in mulberry leaves. This enzyme may also directly regulate the degree of sucrose hydrolysis in the silkworm midgut. In addition, BmSUC1 is involved in the synthesis of sericin 1 in the silk gland tissue. However, the mechanism underlying the regulation of BmSuc1 transcription remains unclear. In this study, we analyzed the BmSuc1 promoter activity using a dual-luciferase reporter assay and identified 4 regions that are critical for transcriptional activation. The gene encoding a predicted transcription factor (TATA-box-binding protein; BmTBP) capable of binding to the core promoter regions was cloned. A quantitative real-time polymerase chain reaction analysis indicated the gene was highly expressed in the midgut. Downregulating BmTBP expression via RNA interference decreased the expression of BmSuc1 at the transcript and protein levels. An electrophoretic mobility shift analysis and chromatin immunoprecipitation indicated that BmTBP can bind to the TATA-box cis-regulatory element in the BmSuc1 promoter. Furthermore, a bioinformatics-based analysis and a far-western blot revealed the interaction between BmTBP and another transcription factor (BmTfIIA-S). The luciferase reporter gene assay results confirmed that the BmTBP-BmTfIIA-S complex increases the BmSuc1 promoter activity. Considered together, these findings suggest that BmTBP regulates BmSuc1 expression through its interaction with BmTfIIA-S.

Defensive Specialized Metabolites from the Latex of Euphorbia jolkinii

Plant latex is sequestered in laticiferous structures and exuded immediately from damaged plant tissues. The primary function of plant latex is related to defense responses to their natural enemies. Euphorbia jolkinii Boiss. is a perennial herbaceous plant that greatly threaten the biodiversity and ecological integrity of northwest Yunnan, China. Nine triterpenes (1-9), four non-protein amino acids (10-13) and three glycosides (14-16) including a new isopentenyl disaccharide (14), were isolated and identified from the latex of E. jolkinii. Their structures were established on the basis of comprehensive spectroscopic data analyses. Bioassay revealed that meta-tyrosine (10) showed significant phytotoxic activity, inhibiting root and shoot growth of Zea mays, Medicago sativa, Brassica campestris, and Arabidopsis thaliana, with EC50 values ranging from 4.41 ± 1.08 to 37.60 ± 3.59 µg/mL. Interestingly, meta-tyrosine inhibited the root growth of Oryza sativa, but promoted their shoot growth at the concentrations below 20 µg/mL. meta-Tyrosine was found to be the predominant constituent in polar part of the latex extract from both stems and roots of E. jolkinii, but undetectable in the rhizosphere soil. In addition, some triterpenes showed antibacterial and nematicidal effects. The results suggested that meta-tyrosine and triterpenes in the latex might function as defensive substances for E. jolkinii against other organisms.

Natural products in cosmetics

The global cosmetics market reached US$500 billion in 2017 and is expected to exceed US$800 billion by 2023, at around a 7% annual growth rate. The cosmetics industry is emerging as one of the fastest-growing industries of the past decade. Data shows that the Chinese cosmetics market was US$60 billion in 2021. It is expected to be the world's number one consumer cosmetics market by 2050, with a size of approximately US$450 billion. The influence of social media and the internet has raised awareness of the risks associated with the usage of many chemicals in cosmetics and the health benefits of natural products derived from plants and other natural resources. As a result, the cosmetic industry is now paying more attention to natural products. The present review focus on the possible applications of natural products from various biological sources in skin care cosmetics, including topical care products, fragrances, moisturizers, UV protective, and anti-wrinkle products. In addition, the mechanisms of targets for evaluation of active ingredients in cosmetics and the possible benefits of these bioactive compounds in rejuvenation and health, and their potential role in cosmetics are also discussed.

The role of selected nutraceuticals in management of prediabetes and diabetes: An updated review of the literature

Dysglycemia is a disease state preceding the onset of diabetes and includes impaired fasting glycemia and impaired glucose tolerance. This review aimed to collect and analyze the literature reporting the results of clinical trials evaluating the effects of selected nutraceuticals on glycemia in humans. The results of the analyzed trials, generally, showed the positive effects of the nutraceuticals studied alone or in association with other supplements on fasting plasma glucose and post-prandial plasma glucose as primary outcomes, and their efficacy in improving insulin resistance as a secondary outcome. Some evidences, obtained from clinical trials, suggest a role for some nutraceuticals, and in particular Berberis, Banaba, Curcumin, and Guar gum, in the management of prediabetes and diabetes. However, contradictory results were found on the hypoglycemic effects of Morus, Ilex paraguariensis, Omega-3, Allium cepa, and Trigonella faenum graecum, whereby rigorous long-term clinical trials are needed to confirm these data. More studies are also needed for Eugenia jambolana, as well as for Ascophyllum nodosum and Fucus vesiculosus which glucose-lowering effects were observed when administered in combination, but not alone. Further trials are also needed for quercetin.

Milking the Bodhi Tree: Mulberry for Disease Demons in Yōsai’s Record of Nourishing Life by Drinking Tea (Kissa yōjōki)

In light of new discoveries of his writings, recent studies on the medieval Japanese monk Yōsai (or Eisai; 1141–1215) have moved away from longstanding preoccupations with his role in establishing Zen in Japan and instead stress his career-long orientation as an esoteric Buddhist monk of the Tendai school. Although these revisions have led to innovative readings of his promotion of tea in the first fascicle of his Record of Nourishing Life by Drinking Tea (Kissa yōjōki), similar approaches have yet to be attempted for the second fascicle of this well-known work, in which Yōsai argues for the apotropaic efficacy of mulberry against pathogenic demons. In this article, I seek to remedy this gap firstly by situating Yōsai’s healing program within broader contemporary trends in esoteric ritual healing. Examining the place of mulberry across esoteric liturgical discourse reveals a rich semiotic network in which the tree was tied to three other key ritual and medicinal materials: milkwood, milk, and the bodhi tree. In the second half of the article, I explore the ways that Yōsai’s argument for mulberry’s efficacy was shaped by an “exoteric” source, namely the biography of Śākyamuni Buddha. In this way, my analysis of the Kissa yōjōki provides insight into the interplay of “esoteric” and “exoteric” elements in Yōsai’s thought and career, even as attention to the specificity of his therapeutic claims for mulberry encourages us to move beyond sectarian frameworks.

A Comparative Analysis of Bombyx mori (Lepidoptera: Bombycidae) β-fructofuranosidase Homologs Reveals Different Post-Translational Regulations in Glyphodes pyloalis Walker (Lepidoptera: Pyralidae)

Simple Summary

The β-fructofuranosidase (β-FFase) encoding gene BmSuc1 regulates the glycometabolism of silkworm larvae, and it participates in the resistance of mulberry alkaloids. However, there is no molecular or biochemical information available about the mulberry pest Glyphodespyloalis Walker β-FFase homologs. In this paper, we have obtained five β-FFase homologous genes in G. pyloalis and characterized the expression and the localization of GpSUC1a in the midgut. The β-FFase activity in the midgut of G. pyloalis larvae and GpSUC1a were both confirmed, while recombinant GpSUC1a displayed little activity as compared with the higher activity of BmSUC1. Some putative N-glycosylation sites were found in GpSUC1a but none in BmSUC1, while there was more methylation in BmSUC1 than in GpSUC1a. The results indicate that such post-translational modifications (PTMs) are differentially supporting that β-FFase are active in these two mulberry feeding caterpillars, and the activation of GpSUC1a may be controlled by a more complex post-translational regulatory system in G. pyloalis larvae. This is the first report on the characterization of β-FFase genes from G. pyloalis and the first comparison of expression regulation between two mulberry feeding insects B. mori and G. pyloalis. Moreover, this research may provide new ideas for the management of mulberry borers.

Abstract

The silk-spinning and Lepidopteran model insect Bombyx mori (Bombycidae) is a mulberry specialist. The BmSuc1 gene is the first β-fructofuranosidase (β-FFase) encoding gene identified in animals, and β-FFase acts as an essential sucrase for glycometabolism modulation in the silkworm larvae, involved in resistance to mulberry alkaloids. Glyphodes pyloalis Walker (Lepidoptera: Pyralidae) is an important mulberry pest leading to heavy economic loss of sericulture. However, no molecular or biochemical information is available about G. pyloalis β-FFase homologs. In this study, five β-FFase homologous genes in G. pyloalis were obtained. The genes GpSuc1a and GpSuc2c were expressed in the midgut; GpSuc2c encodes a truncated polypeptide. The expression and the localization of GpSUC1a in the midgut was characterized. Whereas recombinant GpSUC1a expressed in both Escherichia coli and BmN cells displayed little activity as compared with higher activity of BmSUC1, β-FFase activity in the larval midgut of G. pyloalis and GpSUC1a purified from the midgut were both confirmed. The data suggested that the activation of GpSUC1a is probably controlled by a more complicated post-translational regulation system in G. pyloalis larvae than that of BmSUC1 in B. mori. To study post-translational modifications (PTMs), GpSUC1a and BmSUC1 were purified from larval midguts using immunoprecipitation and subjected to LC-MS to perform PTMs analysis. Some putative N-glycosylated sites were found in GpSUC1a but none in BmSUC1, while there was more methylation in BmSUC1 than in GpSUC1a, indicating that such PTMs were supporting the differential β-FFases activities in these two mulberry feeding caterpillars.

Haemolymph metabolomic differences in silkworms (Bombyx mori L.) under mulberry leaf and two artificial diet rearing methods

The new technology of silkworm (Bombyx mori L.) artificial feed breeding has many characteristics and advantages. This study assessed silkworm rearing with mulberry leaf at all instars (MF) as the control, and used metabolomics to explore the differences in haemolymph metabolism of fifth instar silkworms under two modes of rearing with an artificial diet at all instars (AF) and rearing with an artificial diet during first to third instars and mulberry leaf during the fourth and fifth instars (AMF). The results show that, compared with silkworms of the MF group, the amount and fold change of various metabolites were higher in the haemolymph of AF group silkworms, and the metabolism of amino acids and uric acid, carbohydrates, lipids, and vitamins were changed. These changes may be the reasons for the poor performance of the AF silkworms. However, the amount and fold change of the various metabolites of silkworms in the AMF group were lower, and some metabolic pathways were more active. The amount of material and energy supply were greater. These changes could explain the high efficiency growth of body weight of silkworms after the conversion from artificial diet rearing to mulberry leaf rearing. These findings provide an important theoretical basis for the optimisation of artificial diet rearing technology for silkworms.

Effect of Mulberry Leaf powder on reproductive performance, serum indexes and milk amino acid composition in lactating sows

Experiment was conducted to study the effects of Mulberry Leaf (ML) powder on reproductive performance, serum and milk amino acid composition in sows. Fifty sows (D 85 at gestation) with parity 3 or 4 were randomly divided into 5 groups: C, M100, M200, M300 and M400, receiving 0, 100, 200, 300 and 400 g ML powder per sow per day. Blood and milk of sows at Days 1 and 21 of lactation were collected. Results showed that average daily feed intake (ADFI) during lactation was higher in groups supplemented ML compared with control group (p < 0.01). Litter weight gain during lactation was higher in M400 than in groups M200 and C (p < 0.05), with no significant difference compared with M100 and M300. Serum glucose concentration in groups M400 and M300 was higher than those in the other groups (p < 0.01). Serum HDL-C concentration in group M400 was significantly greater than those in groups M100 and M200 (p < 0.05), with no significant difference between group M400 and groups M300, control. Milk amino acid concentrations such as isoleucine, leucine, lysine and valine were all lower in group M400 than in control (p < 0.01). Serum methionine (Met) concentration was higher in M300 than in other groups (p < 0.01). Milk Met concentration in group C was higher than those of the sows in the group M400, with no significant difference compared with groups M100, M200 and M300 (p < 0.05). Serum Lys and Met concentrations were lower in M400 than in control group (p < 0.05). In summary, our results have revealed the ML supplementation at a high dose such as 300 g/day during later gestation and lactation showed benefit in regulating lipid and amino acid metabolism in sows and then improved growth performance of their offspring.

A comprehensive review on the production, pharmacokinetics and health benefits of mulberry leaf iminosugars: Main focus on 1-deoxynojirimycin, d-fagomine, and 2-O-ɑ-d-galactopyranosyl-DNJ

Mulberry leaves are rich in biologically active compounds, including phenolics, polysaccharides, and alkaloids. Mulberry leaf iminosugars (MLIs; a type of polyhydroxylated alkaloids), in particular, have been gaining increasing attention due to their health-promoting effects, including anti-diabetic, anti-obesity, anti-hyperglycemic, anti-hypercholesterolemic, anti-inflammatory, and gut microbiota-modulatory activities. Knowledge regarding the in vivo bioavailability and bioactivity of MLIs are crucial to understand their role and function and human health. Therefore, this review is aimed to comprehensively summarize the existing studies on the oral pharmacokinetics and the physiological significance of selected MLIs (i.e.,1-deoxynojirimycin, d-fagomine, and 2-O-ɑ-d-galactopyranosyl-DNJ). Evidence have suggested that MLIs possess relatively good uptake and safety profiles, which support their prospective use for oral intake; the therapeutic potential of these compounds against metabolic and chronic disorders and the underlying mechanisms behind these effects have also been studied in in vitro and in vivo models. Also discussed are the biosynthetic pathways of MLIs in plants, as well as the agronomic and processing factors that affect their concentration in mulberry leaves-derived products.

Chemical Differentiation of Plant Latexes and Their Anti-herbivory Activity against Thrips Frankliniella occidentalis

Despite the extensive studies on latex, some fundamental questions on their chemical specialization and the factors influencing this specialization have yet to be investigated. To address this issue, latexes and their bearing tissues from diverse species were profiled by ¹HNMR and GC-MS. Additionally, the antiherbivory activity of these materials was tested against thrips (Frankliniella occidentalis Pergande, 1895). The multivariate data analysis showed a clear separation between latexes and leaves from the same species. Conversely, the chemical profiles of latexes from different species were highly similar, that is, they displayed much less metabolic species-specificity. These shared chemical profiles of latexes were reflected in their overall higher mortality index (80.4% ± 7.5) against thrips compared with their bearing tissues (55.5% ± 14.9). The metabolites correlated to the antiherbivory activity of latexes were triterpenoids and steroids. However, the activity could not be attributed to any single terpenoid. This discrepancy and the reduction of the latex activity after fractionation suggested a complementary effect of the compounds when in a mixture as represented by the latex. Additionally, aqueous fractions of several latexes were found to possess simple spectra, even with only 1 metabolite. These metabolites were determined to be organic acids that might be involved in the modulation of the rate of latex coagulation, potentially increasing the sealing and trapping effects of the latex.

Comparative genomic analysis of azasugar biosynthesis

Azasugars are monosaccharide analogs in which the ring oxygen is replaced with a nitrogen atom. These well-known glycosidase inhibitors are of interest as therapeutics, yet several aspects of azasugars remain unknown including their distribution, structural diversity, and chemical ecology. The hallmark signature of bacterial azasugar biosynthesis is a three gene cluster (3GC) coding for aminotransferase, phosphatase, and dehydrogenase enzymes. Using the bioinformatics platform Enzyme Similarity Tool (EST), we identified hundreds of putative three gene clusters coding for azasugar production in microbial species. In the course of this work, we also report a consensus sequence for the aminotransferase involved in azasugar biosynthesis as being: SGNXFRXXXFPNXXXXXXXLXVPXPYCXRC. Most clusters are found in Bacillus and Streptomyces species which typically inhabit soil and the rhizosphere, but some clusters are found with diverse species representation such as Photorhabdus and Xenorhabdus which are symbiotic with entomopathogenic nematodes; the human skin commensal Cutibacterium acnes, and the marine Bacillus rugosus SPB7, a symbiont to the sea sponge Spongia officinalis. This pan-taxonomic survey of the azasugar 3GC signature may lead to the identification of new azasugar producers, facilitate studies of their natural functions, and lead to new potential therapeutics.

Determination of 1-Deoxynojirimycin (1-DNJ) in Leaves of Italian or Italy-Adapted Cultivars of Mulberry (Morus sp.pl.) by HPLC-MS

Recently, 1-DNJ has been widely studied by scientists for its capacity to inhibit α-glucosidase and reduce postprandial blood glucose and fat accumulation. To the best of our knowledge, this is the first analytical determination of 1-DNJ in Morus sp.pl. leaves carried out on Italian crops, and it could be used as a reference to assess the quality of the plant material in comparison to Far Eastern Asia cultivations. The effects of two thermal treatments were compared to test the incidence of the drying process on the 1-DNJ extractability. In addition, two harvesting seasons in the same year (2017) and two subsequent harvesting years (2017-2018) were considered. The amount of 1-DNJ herein found was comparable to that reported in the scientific literature for Asian cultivations. The increase in 1-DNJ along the summer and the higher level of this compound in the apical leaves also complies with previous findings. However, a strong implication for the climatic conditions in the different years and a significant interaction between climate and genotypes suggest exploring very carefully the agronomic practices and selecting cultivars according to different environmental conditions with a view to standardize the 1-DNJ amount in leaves.

Comparative transcriptomics of leaves of five mulberry accessions and cataloguing structural and expression variants for future prospects

Bombyx mori, a monophagous insect, prefers leaves of the certain species of Morus more than others. The preference has been attributed to morphological and anatomical features and biochemical compounds. In the present manuscript a comparison has been made among the transcriptome of leaves of the two preferred cultivated varieties and three wild types species. While assembling, high quality transcriptomes of five genotypes were constructed with a total of 100930, 151245, 89724, 181761 and 102908 transcripts from ML, MN, MS, K2 and V1 samples respectively. Further, to compare them, orthologs were identified from these assembled transcriptome. A total of 22462, 23413, 23685, 24371, 18362, 22326, 20058, 18049, 17567 and 20518 clusters of orthologs were found in one to one comparison in KvsN, KvsL, KvsS, KvsV, LvsN, LvsS, LvsV, NvsS, NvsV, and SvsV respectively. 4236 orthologs with algebraic connectivity of 1.0 were then used to compare and to find out differentially expressed transcripts from all the genotypes. A total of 1037 transcripts expressed that include some of the important morphology, anatomy and biochemical pathways regulating transcription factors (AP2/ERFs and C2H2 Zinc fingers) and signalling components were identified to express differentially. Further, these transcriptomes were used find out markers (SSR) and variants and a total of 1101013, 537245, 970877, 310437, 675772, 338400, 581189, 751477, 514999 and 257107 variants including SNP, MNP, Insertions and deletions were found in one to one comparisons. Taken together, our data could be highly useful for mulberry community worldwide as it could be utilized in mulberry breeding programs.

Latex Metabolome of Euphorbia Species: Geographical and Inter-Species Variation and its Proposed Role in Plant Defense against Herbivores and Pathogens

Based on the hypothesis that the variation of the metabolomes of latex is a response to selective pressure and should thus be affected differently from other organs, their variation could provide an insight into the defensive chemical selection of plants. Metabolic profiling was used to compare tissues of three Euphorbia species collected in diverse regions. The metabolic variation of latexes was much more limited than that of other organs. In all the species, the levels of polyisoprenes and terpenes were found to be much higher in latexes than in leaves and roots of the corresponding plants. Polyisoprenes were observed to physically delay the contact of pathogens with plant tissues and their growth. A secondary barrier composed of terpenes in latex and in particular, 24-methylenecycloartanol, exhibited antifungal activity. These results added to the well-known role of enzymes also present in latexes, show that these are part of a cooperative defense system comprising biochemical and physical elements.

Horizontal Gene Transfer and Gene Duplication of β-Fructofuranosidase Confer Lepidopteran Insects Metabolic Benefits

Horizontal gene transfer (HGT) is a potentially critical source of material for ecological adaptation and the evolution of novel genetic traits. However, reports on posttransfer duplication in organism genomes are lacking, and the evolutionary advantages conferred on the recipient are generally poorly understood. Sucrase plays an important role in insect physiological growth and development. Here, we performed a comprehensive analysis of the evolution of insect β-fructofuranosidase transferred from bacteria via HGT. We found that posttransfer duplications of β-fructofuranosidase were widespread in Lepidoptera and sporadic occurrences of β-fructofuranosidase were found in Coleoptera and Hymenoptera. β-fructofuranosidase genes often undergo modifications, such as gene duplication, differential gene loss, and changes in mutation rates. Lepidopteran β-fructofuranosidase gene (SUC) clusters showed marked divergence in gene expression patterns and enzymatic properties in Bombyx mori (moth) and Papilio xuthus (butterfly). We generated SUC1 mutations in B. mori using CRISPR/Cas9 to thoroughly examine the physiological function of SUC. BmSUC1 mutant larvae were viable but displayed delayed growth and reduced sucrase activities that included susceptibility to the sugar mimic alkaloid found in high concentrations in mulberry. BmSUC1 served as a critical sucrase and supported metabolic homeostasis in the larval midgut and silk gland, suggesting that gene transfer of β-fructofuranosidase enhanced the digestive and metabolic adaptation of lepidopteran insects. These findings highlight not only the universal function of β-fructofuranosidase with a link to the maintenance of carbohydrate metabolism but also an underexplored function in the silk gland. This study expands our knowledge of posttransfer duplication and subsequent functional diversification in the adaptive evolution and lineage-specific adaptation of organisms.

Expression of a gene for an MLX56 defense protein derived from mulberry latex confers strong resistance against a broad range of insect pests on transgenic tomato lines

Insect pests cause serious damage in crop production, and various attempts have been made to produce insect-resistant crops, including the expression of genes for proteins with anti-herbivory activity, such as Bt (Bacillus thuringiensis) toxins. However, the number of available genes with sufficient anti-herbivory activity is limited. MLX56 is an anti-herbivory protein isolated from the latex of mulberry plants, and has been shown to have strong growth-suppressing activity against the larvae of a variety of lepidopteran species. As a model of herbivore-resistant plants, we produced transgenic tomato lines expressing the gene for MLX56. The transgenic tomato lines showed strong anti-herbivory activities against the larvae of the common cutworm, Spodoptera litura. Surprisingly, the transgenic tomato lines also exhibited strong activity against the attack of western flower thrips, Frankliniera occidentalis. Further, growth of the hadda beetle, Henosepilachna vigintioctopunctata, fed on leaves of transgenic tomato was significantly retarded. The levels of damage caused by both western flower thrips and hadda beetles were negligible in the high-MLX56-expressing tomato line. These results indicate that introduction of the gene for MLX56 into crops can enhance crop resistance against a wide range of pest insects, and that MLX56 can be utilized in developing genetically modified (GM) pest-resistant crops.

Structural insight into the substrate specificity of Bombyx mori β-fructofuranosidase belonging to the glycoside hydrolase family 32

Sucrose-hydrolyzing enzymes are largely divided into β-fructofuranosidase and sucrose α-glucosidase. The domestic silkworm Bombyx mori possesses both enzymes, BmSUC1 and BmSUH, belonging to the glycoside hydrolase family 32 (GH32) and GH13, respectively. BmSUC1 was presumed to be acquired by horizontal gene transfer from bacteria based on phylogenetic analysis and related to tolerance to sugar-mimic alkaloids contained in mulberry latex. Here we investigated the substrate specificity of recombinant BmSUC1 that can hydrolyze not only sucrose but also fructooligosaccharides and fructans, and revealed that the enzyme was competitively inhibited by 1,4-dideoxy-1,4-imino-D-arabinitol, one of the alkaloids. Moreover, the crystal structures of BmSUC1 in apo form and complex with sucrose were determined, and the active site pocket was shallow and suitable for shorter substrates but was related to more relaxed substrate specificity than the strict sucrose α-glucosidase BmSUH. Considering together with the distribution of BmSUC1-orthologous genes in many lepidopterans, our results suggest that BmSUC1 contributes to the digestion of fructooligosaccharides and fructans derived from feed plants.

Physiological adaptations to sugar-mimic alkaloids: Insights from Bombyx mori for long-term adaption and short-term response

Insects evolved adaptive plasticity to minimize the effects of the chemical defenses of their host plants. Nevertheless, the expressional response and adaptation of phytophagous specialists for long-term adaption and short-term response to host phytochemicals remains largely unexplored. The mulberry (Morus alba)-silkworm (Bombyx mori) interaction is an old and well-known model of plant-insect interaction. In this study, we examined the long-term adaption and short-term response of the mulberry-specialist silkworm to two sugar-mimic alkaloids in mulberry: the commonly encountered 1-deoxynojirimycin (1-DNJ) and occasionally encountered 1,4-dideoxy-1,4-imino-D-arabinitol (D-AB1), respectively. Global transcriptional patterns revealed that the physiological responses induced by the selective expression of genes involved in manifold cellular processes, including detoxification networks, canonical digestion processes, target enzymes, and other fundamental physiological processes, were crucial for regulating metabolic homeostasis. Comparative network analysis of the effects of exposure to D-AB1 and 1-DNJ supported the contention that B. mori produced similar and specific trajectories of changed gene expression in response to different sugar-mimic alkaloids. D-AB1 elicited a substantial proportion of downregulated genes relating to carbohydrate metabolism, catabolic process, lipid metabolism, and glycan biosynthesis and metabolism. This study dramatically expands our knowledge of the physiological adaptations to dietary sugar-mimic alkaloid intake and uncovered both metabolic evolutionarily responses and unique adaptive mechanisms previously unknown in insects.

New Frontiers on Human Safe Insecticides and Fungicides: An Opinion on Trehalase Inhibitors

In the era of green economy, trehalase inhibitors represent a valuable chance to develop non-toxic pesticides, being hydrophilic compounds that do not persist in the environment. The lesson on this topic that we learned from the past can be of great help in the research on new specific green pesticides. This review aims to describe the efforts made in the last 50 years in the evaluation of natural compounds and their analogues as trehalase inhibitors, in view of their potential use as insecticides and fungicides. Specifically, we analyzed trehalase inhibitors based on sugars and sugar mimics, focusing on those showing good inhibition properties towards insect trehalases. Despite their attractiveness as a target, up to now there are no trehalase inhibitors that have been developed as commercial insecticides. Although natural complex pseudo di- and trisaccharides were firstly studied to this aim, iminosugars look to be more promising, showing an excellent specificity profile towards insect trehalases. The results reported here represent an overview and a discussion of the best candidates which may lead to the development of an effective insecticide in the future.

Structure-function analysis of silkworm sucrose hydrolase uncovers the mechanism of substrate specificity in GH13 subfamily 17 exo-α-glucosidases

The domestic silkworm Bombyx mori expresses two sucrose-hydrolyzing enzymes, BmSUH and BmSUC1, belonging to glycoside hydrolase family 13 subfamily 17 (GH13_17) and GH32, respectively. BmSUH has little activity on maltooligosaccharides, whereas other insect GH13_17 α-glucosidases are active on sucrose and maltooligosaccharides. Little is currently known about the structural mechanisms and substrate specificity of GH13_17 enzymes. In this study, we examined the crystal structures of BmSUH without ligands; in complexes with substrates, products, and inhibitors; and complexed with its covalent intermediate at 1.60-1.85 Å resolutions. These structures revealed that the conformations of amino acid residues around subsite -1 are notably different at each step of the hydrolytic reaction. Such changes have not been previously reported among GH13 enzymes, including exo- and endo-acting hydrolases, such as α-glucosidases and α-amylases. Amino acid residues at subsite +1 are not conserved in BmSUH and other GH13_17 α-glucosidases, but subsite -1 residues are absolutely conserved. Substitutions in three subsite +1 residues, Gln¹⁹¹, Tyr²⁵¹, and Glu⁴⁴⁰, decreased sucrose hydrolysis and increased maltase activity of BmSUH, indicating that these residues are key for determining its substrate specificity. These results provide detailed insights into structure-function relationships in GH13 enzymes and into the molecular evolution of insect GH13_17 α-glucosidases.

Anti-diabetic potential of plant alkaloids: Revisiting current findings and future perspectives

Diabetes mellitus (DM) is a chronic metabolic disease which causes millions of death all over the world each year, and its incidence is on increase. The most prevalent form, type 2 DM, is characterized by insulin resistance and β-cell dysfunction, whereas type 1 DM is due to insulin deficiency as a result of β-cell destruction. Various classes of synthetic drugs have been developed to regulate glucose homeostasis and combat the development of late-diabetic complications. However, several of these chemical agents are either sub-optimal in their effect and/or may have side effects. Biologically, alkaloids unveiled a wide range of therapeutic effects including anti-diabetic properties. The chemical backbones of these compounds have the potential to interact with a wide range of proteins involved in glucose homeostasis, and thus they have received increasing attention as reliable candidates for drug development. This review sets out to investigate the anti-diabetic potential of plant alkaloids (PAs), and therefore, scientific databases were comprehensively screened to highlight the biological activity of 78 PAs with a considerable anti-diabetic profile. There are not enough clinical data available for these phytochemicals to follow their fingerprint in human, but current studies generally recommending PAs as potent α-glucosidase inhibitors. Except for some classes of monoterpene alkaloids, other compounds showed similar features as well as the presently available anti-diabetic drugs such as amino sugars and other relevant drugs. Moreover, the evidence suggests that PAs have the potential to be used as alternative additives for the treatment of DM, however, further in vitro and in vivo studies are needed to validate these findings.

iTRAQ-Based Quantitative Proteomic Analysis of Digestive Juice across the First 48 Hours of the Fifth Instar in Silkworm Larvae

The silkworm is an oligophagous insect for which mulberry leaves are the sole diet. The nutrients needed for vital activities of the egg, pupal, and adult stages, and the proteins formed in the cocoon, are all derived from the larval stages. The silkworm feeds and grows quickly during the larval stages. In particular, the amount of leaf ingested and digested quickly increases from the ecdysis to the gluttonous stage in the fifth instar period. In this study, we used the iTRAQ proteomic technique to identify and analyze silkworm larval digestive juice proteins during this period. A total of 227 proteins were successfully identified. These were primarily serine protease activity, esterase activity, binding, and serine protease inhibitors, which were mainly involved in the digestion and overcoming the detrimental effects of mulberry leaves. Moreover, 30 genes of the identified proteins were expressed specifically in the midgut. Temporal proteomic analysis of digestive juice revealed developmental dynamic features related to molecular mechanisms of the principal functions of digesting, resisting pathogens, and overruling the inhibitory effects of mulberry leaves protease inhibitors (PIs) with a dynamic strategy, although overruling the inhibitory effects has not yet been confirmed by previous study. These findings will help address the potential functions of digestive juice in silkworm larvae.

Plant Defense by Latex: Ecological Genetics of Inducibility in the Milkweeds and a General Review of Mechanisms, Evolution, and Implications for Agriculture

Latex occurs in 10% of plant families, has evolved independently many times, and is the most effective defense of milkweeds against its chewing herbivores. Here we report on new experiments on the heritability and inducibility of latex in several milkweed species. In addition, we review what is known about the genetic and environmental determinants of latex exudation, hormonal regulation, evolution within and among species, and the role and frequency of latex in agricultural crops. We first evaluated genotype-by-environment interactions using ~20 full-sibling genetic families in each of seven Asclepias species treated as controls or attacked by monarch butterfly caterpillars. All species showed substantial genetic variation for latex exudation and six of seven species responded to monarch herbivory (two species increased latex, two species decreased, and two showed variation among genetic families). Exogenous application of jasmonic acid (JA) to three species induced a consistent increase in latex (including species which showed a decline following caterpillar herbivory). We next evaluated three hypotheses for what determines genetic variation for induced latex in A. syriaca: 1) a trade-off with constitutive investment, 2) differential endogenous JA induction, or 3) variation in responsiveness to JA. We only found support for the second hypothesis: genetic families with a stronger JA-burst showed the greatest latex exudation following herbivory. We conclude that most species exhibit a genetic and inducible basis for latex, although genetic variation in inducibility is not pervasive. Finally, we summarized studies across 22 species of Asclepias and found that neither a species' latitude nor its phylogenetic position predicted latex inducibility. Nonetheless, a negative association between constitutive and induced latex across species indicates a macroevolutionary trade-off in allocation to this defense. Our review indicates that jasmonic acid is a key regulator of latex exudation, laticifer morphology, and defensive metabolites within latex. Biotic and abiotic factors strongly modulate latex expression. A survey of latex in food crops revealed that latex and analogous exudates (gums, resins, mucilage) are more common than expected based on their distribution across all plants. In conclusion, despite its widespread occurrence, the literature on latex is currently dominated by rubber trees and milkweeds, and we look forward to the broadening of ecological, agricultural, and mechanistic research into other systems.

Functional annotation of mulberry (Morus spp.) transcriptome, differential expression of genes related to growth and identification of putative genic SSRs, SNPs and InDels

Growth is a complex trait associated with mulberry leaf yield and controlled by several genes. In this study, we have explored the molecular basis underlying growth using Transcriptome profiling of contrasting genotypes. A total of 66.6 Mbp of primary transcriptomes from high growth (HGG)-Jalalgarah-3 and M. laevigata (H) and, low growth genotypes (LGG)-Harmutty and Vadagaraparai-2; resulting in 24210, 27998, 28085 and 28764 final transcripts respectively. Out of the 34096 pooled transcripts, 20249 transcripts matched with at least one sequence of the non-redundant database. Functional annotation resulted in the categorization of 18970 transcripts into 3 gene ontology (GO) terms and 7440 were assigned to 23 Kyoto encyclopaedia of genes and genomes (KEGG) pathway. Based on the differentially expressed genes and gene enrichment analysis, over expression of photosynthetic related transcripts in HGG and defence related transcripts in LGG were noted. Simple sequence repeats were mined from unique transcripts and the most abundant motifs were tri- (1883) followed by di- (1710), tetra- (192), penta- (68) and hexa- (40) repeats. Further, a total of 390897 high quality SNPs and 8081 InDels were identified by mapping onto Morus notabilis reference genome. The study provides an insight into the expression of genes involved in growth and further research on utilization in gentic improvement of the crop.

The peritrophic membrane as a target of proteins that play important roles in plant defense and microbial attack

The peritrophic membrane (or peritrophic matrix: PM) is a thin membranous structure that lies along the midgut epithelium in the midgut lumen and consists of chitin and proteins. PM exists between ingested food material and midgut epithelium cells and it is on the frontline of insect-plant and insect-microbe interactions. Therefore, proteins that play major roles in plant defense against herbivorous insects and in microbial attack on insects should penetrate, destroy or modify the PM to accomplish their roles. Recently, it has become clear that some proteins crucial to plant defense or microbial attack have the PM as their primary target. In addition, several plant defense proteins have been reported to affect the PM, although it is still unclear whether the PM is their primary target. This review introduces several of these proteins: fusolin and enhancin, two proteins produced by insect viruses that greatly enhance infection of the viruses by disrupting the PM; the MLX56 family proteins found in mulberry latex as defense proteins against insect herbivores, which modify the PM to a thick structure that inhibits digestive processes; Mir1-CP, a defense cysteine protease from maize that inhibits the growth of insects at very low concentrations and degrades the PM structures; and chitinases and lectins. The importance, necessary characteristics, and modes of action of PM-targeting proteins are then discussed from a strategic point of view, by spotlighting the importance of selective permeability of the PM. Finally, the review discusses the possibility of applying PM-targeting proteins for the control of pest insects.

Distribution and Characteristics of Transposable Elements in the Mulberry Genome

Mulberry ( C. K. Schneid) leaves have been used as the food for the domesticated silkworm, , for more than 5000 yr, and the mulberry-silkworm relationship is one of the best-known and oldest models of plant defense-insect adaptation. The availability of a genome assembly of mulberry provides us with an opportunity to mine the characteristics and distribution of transposable elements (TEs) in this species and to examine their relationship to genes and gene expression. In this study, a significantly correlated inverse relationship between the percentage coverage of genes and TEs was observed. The TE-rich regions appeared to have a lower percentage of putatively expressed genes. Distribution patterns between different TE superfamilies were detected in the mulberry genome. The elements (the TE making up the greatest proportion of the mulberry genome) were significantly overrepresented within genes in the mulberry genome, and they may have a dominant influence on evolution of the mulberry genome. Approximately 96.93% (330/344) of the TE-containing genes assigned to pathways were assigned to metabolism-related pathways. The TE-related alternative splicing events accounted for 7.58% (402/5,302) of all alternative splicing types in the mulberry genome, suggesting that TEs are one of the driving forces in the formation of the alternatively spliced genes. The results will be valuable in improving our understanding of the important roles of TEs in mulberry genome evolution.

Bioactive tigliane diterpenoids from the latex of Euphorbia fischeriana

Latex is a type of sticky endogenous fluids derived from diverse plants including Euphorbia fischeriana, and is of great scientific and commercial values. In the current study, it was demonstrated that the latex extracted from E. fischeriana strongly respelled the growth of cotton bollworm, Helicoverpa armigera. Using spectroscopic methods, HPLC, and GC-MS analyses, six aliphatic tigliane diterpenoids were isolated from the latex of E. fischeriana, among which three compounds (2, 3, and 5) were new. Two major compounds (1 and 4) exhibited remarkable antifeedant activity against H. armigera, with EC₅₀ values at 2.59 and 15.32 μg/cm², respectively. In addition, the quantification analysis of diterpenoids in different organs indicated that 4 was the most abundant constituent and was highly accumulated in the latex. Collectively, the current study highlighted that the diterpenoids in latex of E. fischeriana had a considerable antifeedant function against H. armigera, which might be employed for the future development of natural insecticides for organic farming.

Comparative analysis of seven types of superoxide dismutases for their ability to respond to oxidative stress in Bombyx mori

Insects are well adapted to changing environmental conditions. They have unique systems for eliminating reactive oxygen species (ROS). Superoxide dismutase (SOD) is a key enzyme that plays a primary role in removing ROS. Bombyx mori is a lepidopteran insect, whose body size is larger than the model insect Drosophila melanogaster, which enabled us to more easily examine gene expression at the tissue level. We searched B. mori SOD (BmSOD) genes using genome database, and we analyzed their function under different type of oxidative stress. Consequently, we identified four new types of BmSODs in addition to the three types already known. Two of the seven types had a unique domain architecture that has not been discovered previously in the SOD family, and they were expressed in different tissues and developmental stages. Furthermore, these BmSODs responded differently to several kinds of stressors. Our results showed that the seven types of BmSODs are likely to play different roles in B. mori; therefore, B. mori could be used to distinguish the functions of each SOD for resistance to oxidative stress that changes with the environmental conditions.

Nutraceutical and Medicinal Potential of the Morus Species in Metabolic Dysfunctions

Many populations use medicinal plants as a therapeutic treatment, due to their lower cost and greater access. Among the plant species used for medicinal purposes are those of the genus Morus. The most known species are Morus alba, rubra, and nigra. This review aims to collect data from the literature, predominantly from cell and animal studies, which presents a possible nutraceutical and medicinal potential of the species Morus for use in metabolic dysfunctions. The fruits and leaves of mulberry are used for therapeutic purposes. For scientific confirmation of these effects, they were studied for laxative properties, antibacterial activity, anti-atherogenic activity, and hepatoprotective function. Furthermore, the genus Morus is recognized for the treatment and prevention of diabetes mellitus, through its hypoglycemic action. It may also provide health benefits through immunomodulatory, anti-inflammatory, and anti-nociceptive effects. It has been found that the Morus species have phenolic compounds, flavonoids, and anthocyanins that act as important antioxidants and promote beneficial effects on human health. These phytochemical compounds differ among species. Blackberry (Morus nigra) are rich in flavonoids, while the white mulberry (Morus alba) has low concentrations of flavonoids and anthocyanins. In addition, another important factor is to ensure a complete exemption of toxic risks in the use of medicinal plants for the treatment of diseases. Studies have shown no toxic effects by the administration of extracts of Morus species. Thus, the mulberry tree presents nutraceutical potential. It is therefore a promising alternative for medicinal products based on medicinal plants.

Ontogenic synchronization of Bephratelloides cubensis, Annona macroprophyllata seeds and acetogenins from Annonaceae

The seeds of Annona macroprophyllata Donn. Sm. contain idioblasts with toxic acetogenins, including laherradurin and rolliniastatin-2, in relatively high proportions. Both metabolites are cataloged as potent insecticides for several species, even so, the wasp Bephratelloides cubensis Ashmead fulfills almost its entire life cycle inside the seeds of this and other annonaceous species, to such a degree, that they constitute a strong selection pressure. In order to document the chemical relationship between the two species, it is reported for the first time in this paper the presence of idioblasts and acetogenins during the ontogenic development of the seeds of A. macroprophyllata, and contrasted with the development of B. cubensis. The results indicate that idioblasts with laherradurin and rolliniastatin-2 acetogenins are formed in the middle stages of the endospermic development, also that both acetogenins are biosynthesized simultaneously, and that their proportion is dependent on the degree of development. The acetogenins are present in high amounts that suppose a sufficient toxic barrier and, in this case, laherradurin is the most abundant (> 1000 µg g dry weight^-1). The wasp B. cubensis only emerges from the seeds to copulate and returns for oviposition; its larval phase coincides with the appearance of acetogenins, so it feeds on the acetogenic endosperm. The absence of acetogenins in the tissues and excreta of the insect supposes a metabolization of the molecules, which would explain the tolerance to its toxicity.

A toxicological, metabonomic and transcriptional analysis to investigate the property of mulberry 1-deoxynojirimycin against the growth of Samia cynthia ricini

1-Deoxynojirimycin (DNJ) is a natural d-glucose analogue from mulberry with promising physiological activity in vivo. Up to the present, the antidiabetic effects of DNJ on lowering blood sugar and accelerating lipid metabolism in mammals were broadly reported, but the specific character of DNJ against insects was vastly ignored. In this study, a toxicological test of DNJ againgst eri-silkworm, Samia cynthia ricini was carried out to investigate the potential of DNJ in insect management. Further, a method of nuclear magnetic resonance (NMR) metabonomics and real-time qPCR (RT-qPCR) were performed to analyze the alteration in midgut of eri-silkworm caused by DNJ. The result of toxicology showed that 5% and 10% DNJ could significantly inhibit the development of third-instar larvae on day 1-5, and mass deaths happened in DNJ groups on day 3-5. The quantitative analysis of ¹H NMR in fifth-instar larvae showed that trehalose level increased in midgut of 0, 6 and 12 h DNJ groups, while the concentrations of glucose, lactate, alanine, pyruvate, α-ketoglutarate and fumarate were reduced in varying degrees. Meanwhile, principal component analysis (PCA) indicated that there were significant differences in the metabolic profiles among 12 h DNJ groups and the control group. In addition, RT-qPCR results displayed that four genes coding α-glucosidase, trehalase (THL) and lactate dehydrogenase (LDH) were lowered in expression of 12 h DNJ groups. Simultaneously, THL activity was significantly lowerd in 12 h DNJ groups. These mutually corroborated results indicated that the backbone pathways of energy metabolism, including hydrolysis of trehalose and glycogens, glycolysis and tricarboxylic acid (TCA) cycle were significantly inhibited by DNJ. Thus, the specific mechanism of DNJ efficiently suppressing the growth and energy metabolism of eri-silkworm was explored in this study, providing the potential of DNJ as to the production of botanical insecticide.

Transcriptome analysis and identification of key genes involved in 1-deoxynojirimycin biosynthesis of mulberry (Morus alba L.)

Mulberry (Morus alba L.) represents one of the most commonly utilized plants in traditional medicine and as a nutritional plant used worldwide. The polyhydroxylated alkaloid 1-deoxynojirimycin (DNJ) is the major bioactive compounds of mulberry in treating diabetes. However, the DNJ content in mulberry is very low. Therefore, identification of key genes involved in DNJ alkaloid biosynthesis will provide a basis for the further analysis of its biosynthetic pathway and ultimately for the realization of synthetic biological production. Here, two cDNA libraries of mulberry leaf samples with different DNJ contents were constructed. Approximately 16 Gb raw RNA-Seq data was generated and de novo assembled into 112,481 transcripts, with an average length of 766 bp and an N50 value of 1,392. Subsequently, all unigenes were annotated based on nine public databases; 11,318 transcripts were found to be significantly differentially regulated. A total of 38 unique candidate genes were identified as being involved in DNJ alkaloid biosynthesis in mulberry, and nine unique genes had significantly different expression. Three key transcripts of DNJ biosynthesis were identified and further characterized using RT-PCR; they were assigned to lysine decarboxylase and primary-amine oxidase genes. Five CYP450 transcripts and two methyltransferase transcripts were significantly associated with DNJ content. Overall, the biosynthetic pathway of DNJ alkaloid was preliminarily speculated.

Mulberry (Morus spp.) has the features to treat as a potential perennial model system

Mulberry (Morus spp.), a commercially exploited tree species as the host of monophagous pest silk worm (Bombyx mori), belongs to the family Moraceae. The domesticated tree has diverse beneficial characters such as traits associated with rapid growth and biomass production, plant insect/microbe interaction, abiotic stress tolerance and the traits associated with nutritional and medicinal values; some of which have been exploited. Draft genome of Morus notabilis has been sequenced and a large volume of transcriptome and genomic resources have been generated. In this review an attempt has been made to examine the options for considering mulberry as another tree model system to study unique traits associated with perennial systems. The diverse traits and features in mulberry suggest that the system can be a "comprehensive trait integrated tree system" quite different from other model tree systems.

Expression plasticity and evolutionary changes extensively shape the sugar-mimic alkaloid adaptation of nondigestive glucosidase in lepidopteran mulberry-specialist insects

During the co-evolutionary arms race between plants and herbivores, insects evolved systematic adaptive plasticity to minimize the chemical defence effects of their host plants. Previous studies mainly focused on the expressional plasticity of enzymes in detoxification and digestion. However, the expressional response and adaptive evolution of other fundamental regulators against host phytochemicals are largely unknown. Glucosidase II (GII), which is composed of a catalytic GIIα subunit and a regulatory GIIβ subunit, is an evolutionarily conserved enzyme that regulates glycoprotein folding. In this study, we found that GIIα expression of the mulberry-specialist insect was significantly induced by mulberry leaf extract, 1-deoxynojirimycin (1-DNJ), whereas GIIβ transcripts were not significantly changed. Moreover, positive selection was detected in GIIα when the mulberry-specialist insects diverged from the lepidopteran order, whereas GIIβ was mainly subjected to purifying selection, thus indicating an asymmetrically selective pressure of GII subunits. In addition, positively selected sites were enriched in the GIIα of mulberry-specialist insects and located around the 1-DNJ-binding sites and in the C-terminal region, which could result in conformational changes that affect catalytic activity and substrate-binding efficiency. These results show that expression plasticity and evolutionary changes extensively shape sugar-mimic alkaloids adaptation of nondigestive glucosidase in lepidopteran mulberry-specialist insects. Our study provides novel insights into a deep understanding of the sequestration and adaptation of phytophagous specialists to host defensive compounds.

Study of the effect of the herbal composition SR2004 on hemoglobin A1c, fasting blood glucose, and lipids in patients with type 2 diabetes mellitus

Background

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by raised blood glucose levels and peripheral insulin resistance. It is an increasingly prevalent global healthcare concern. Conventional treatment options are limited and in this context, there is renewed interest in evaluating the clinical and biological effects of traditional therapies. We assess the effect of a new herbal composition SR2004 on the hemoglobin A1c (HbA1c), fasting blood glucose, and lipid profiles of patients with T2DM.

Methods

This is a single center, unblinded, prospective interventional study conducted in Israel. The composition SR2004 includes Morus alba, Artemisia dracunculus, Urtica dioica, Cinnamomum zeylanicum, and Taraxacum officinale. One hundred and nineteen patients with diagnosed T2DM were enrolled and received SR2004 in addition to their usual medications. HbA1c, fasting blood glucose, and lipid profiles at 12 weeks were compared with baseline. In addition, the tolerability and side effects of SR2004 were recorded.

Results

One hundred and three patients completed 12 weeks of follow-up (87%) and were included in the results. At 12 weeks, HbA1c reduced from 9.0% to 7.1% (22%; p < 0.0001), mean blood glucose decreased from 211 mg/dL to 133 mg/dL (37% reduction; p < 0.0001), mean total cholesterol to 185 mg/dL (13% reduction; p < 0.01) and mean serum triglycerides to160 mg/dL (a reduction of 40% from baseline; p < 0.001). Twelve patients (12%) had no response with SR2004 supplementation. In addition, of thirteen patients who took insulin at baseline, five required only oral hypoglycemics and another five reduced their daily insulin requirements by 30% at 12 weeks. Clinical observations included improvements in vasculopathy, including reversal of established retinopathic changes in two patients.

No major adverse effects were observed, with minor abdominal symptoms reported in sixteen patients (16%).

Conclusion

SR2004 supplementation significantly reduced HbA1c, blood glucose, and lipids with good tolerability and no observed adverse interactions with conventional medications. Some interesting findings relating to the reversal of microvascular phenomena warrant further research to elucidate the mechanisms of action of this novel composition.

BmSUC1 is essential for glycometabolism modulation in the silkworm, Bombyx mori

Sucrose is the most commonly transported sugar in plants and is easily assimilated by insects to fulfill the requirement of physiological metabolism. BmSuc1 is a novel animal β-fructofuranosidase (β-FFase, EC 3.2.1.26)-encoding gene that was firstly cloned and identified in silkworm, Bombyx mori. BmSUC1 was presumed to play an important role in the silkworm-mulberry enzymatic adaptation system by effectively hydrolyzing sucrose absorbed from mulberry leaves. However, this has not been proved with direct evidence thus far. In this study, we investigated sucrose hydrolysis activity in the larval midgut of B. mori by inhibition tests and found that sucrase activity mainly stemmed from β-FFase, not α-glucosidase. Next, we performed shRNA-mediated transgenic RNAi to analyze the growth characteristics of silkworm larvae and variations in glycometabolism in vivo in transgenic silkworms. The results showed that in the RNAi-BmSuc1 transgenic line, larval development was delayed, and their body size was markedly reduced. Finally, the activity of several disaccharidases alone in the midgut and the sugar distribution, total sugar and glycogen in the midgut, hemolymph and fat body were then determined and compared. Our results demonstrated that silencing BmSuc1 significantly reduced glucose and apparently activated maltase and trehalase in the midgut. Together with a clear decrease in both glycogen and trehalose in the fat body, we conclude that BmSUC1 acts as an essential sucrase by directly modulating the degree of sucrose hydrolysis in the silkworm larval midgut, and insufficient sugar storage in the fat body may be responsible for larval malnutrition and abnormal petite phenotypes.

Identification and validation of reference genes for qRT-PCR analysis in mulberry (Morus alba L.)

Mulberry (Morus alba L.) is an important economic tree species in many countries. Quantitative real time PCR (qRT-PCR) has become a widely used method for gene expression studies in plants. A suitable reference gene is essential to ensure accurate and reliable results for qRT-PCR analyses. However, no reports describing the selection of reference genes have been published for mulberry. In this work, we evaluated the stability of twenty candidate reference genes in different plant tissues and under different stress conditions by qRT-PCR in mulberry using algorithms in two programs—geNorm and NormFinder. The results revealed that TUB2, UBI4, ACTIN3 and RPL4 were ranked as the most stable reference genes in the samples subsets, whereas EF1α4 and TUB3showed the least stability with both algorithms. To further validate the stability of the reference genes, the expression patterns of six genes of mulberry were analyzed by normalization with the selected reference genes. Our study will benefit future analyses of gene expression in mulberry.

Proteomic-Based Approach to the Proteins Involved in 1-Deoxynojirimycin Accumulation in Silkworm Bombyx mori (Lepidoptera: Bombycidae)

1-Deoxynojirimycin (DNJ) is the most abundant poly-hydroxylated alkaloid in the latex of mulberry leaves and it protects mulberry from insect predation. However, silkworms can survive the poisoning effect of DNJ and accumulate DNJ by consumption of the mulberry leaves. In order to determine the molecular mechanism of DNJ accumulation in silkworm, comparative proteomic analysis was employed to evaluate protein expression in two groups of silkworm bodies (the third instar silkworm bodies had the maximum content of DNJ throughout life, and the newly hatched silkworm bodies had no DNJ). Our results indicated some differentially expressed proteins in the third instar silkworm involved in material metabolism, energy metabolism, oxidation-reduction, detoxification, immune, and transport regulation may correspond to the accumulation of DNJ. Furthermore, the expression levels of five selected differentially expressed protein-encoding genes namely heat shock cognate protein (Hsp 70), glutathione S-transferase sigma 1 (GST), serine protease precursor (Ser), hemolymph protein (30K), and thiol peroxiredoxin (TPx) were investigated by quantitative real-time PCR and the accumulation of DNJ was measured by HPLC. Correlation analysis showed that the expression levels of Hsp70 and Ser were negatively correlated to DNJ accumulation with weak correlation, while 30K, GST, and TPx genes had positive correlation with DNJ accumulation. The findings suggested that these three proteins were probably important in the physiological process of DNJ accumulation in silkworm.

Abnormal swelling of the peritrophic membrane in Eri silkworm gut caused by MLX56 family defense proteins with chitin-binding and extensin domains

MLX56 family defense proteins, MLX56 and its close homolog LA-b, are chitin-binding defense proteins found in mulberry latex that show strong growth-inhibitions against caterpillars when fed at concentrations as low as 0.01%. MLX56 family proteins contain a unique structure with an extensin domain surrounded by two hevein-like chitin-binding domains, but their defensive modes of action remain unclear. Here, we analyzed the effects of MLX56 family proteins on the peritrophic membrane (PM), a thin and soft membrane consisting of chitin that lines the midgut lumen of insects. We observed an abnormally thick (>1/5 the diameter of midgut) hard gel-like membrane consisted of chitin and MLX56 family proteins, MLX56 and LA-b, in the midgut of the Eri silkworms, Samia ricini, fed a diet containing MLX56 family proteins, MLX56 and LA-b. When polyoxin AL, a chitin-synthesis-inhibitor, was added to the diet containing MLX56 family proteins, the toxicity of MLX56 family proteins disappeared and PM became thinner and fragmented. These results suggest that MLX56 family proteins, through their chitin-binding domains, bind to the chitin framework of PM, then through their extensin-domain (gum arabic-like structure), which functions as swelling agent, expands PM into an abnormally thick membrane that inhibits the growth of insects. This study shows that MLX56 family proteins are plant defense lectins with a totally unique mode of action, and reveals the functions of extensin domains and arabinogalactan proteins as swelling (gel-forming) agents of plants.

D181A Site-Mutagenesis Enhances Both the Hydrolyzing and Transfructosylating Activities of BmSUC1, a Novel β-Fructofuranosidase in the Silkworm Bombyx mori

β-fructofuranosidase (β-FFase) belongs to the glycosyl-hydrolase family 32 (GH32), which can catalyze both the release of β-fructose from β-d-fructofuranoside substrates to hydrolyze sucrose and the synthesis of short-chain fructooligosaccharide (FOS). BmSuc1 has been cloned and identified from the silkworm Bombyx mori as a first animal type of β-FFase encoding gene. It was hypothesized that BmSUC1 plays an important role in the silkworm-mulberry adaptation system. However, there is little information about the enzymatic core sites of BmSUC1. In this study, we mutated three amino acid residues (D63, D181, and E234) that represent important conserved motifs for β-FFase activity in GH32 to alanine respectively by using site-directed mutagenesis. Recombinant proteins of three mutants and wild type BmSUC1 were obtained by using a Bac-to-Bac/BmNPV expression system and BmN cells. Enzymatic activity, kinetic properties, and substrate specificity of the four proteins were analyzed. High Performance Liquid Chromatography (HPLC) was used to compare the hydrolyzing and transfructosylating activities between D181A and wtBmSUC1. Our results revealed that the D63A and E234A mutations lost activity, suggesting that D63 and E234 are key amino acid residues for BmSUC1 to function as an enzyme. The D181A mutation significantly enhanced both hydrolyzing and transfructosylating activities of BmSUC1, indicating that D181 may not be directly involved in catalyzation. The results provide insight into the chemical catalyzation mechanism of BmSUC1 in B. mori. Up-regulated transfructosylating activity of BmSUC1 could provide new ideas for using B. mori β-FFase to produce functional FOS.

Comparative transcriptome analysis reveals significant metabolic alterations in eri-silkworm (Samia cynthia ricini) haemolymph in response to 1-deoxynojirimycin

Samia cynthia ricini (Lepidoptera: Saturniidae) is an important commercial silk-producing insect; however, in contrast to the silkworm, mulberry leaves are toxic to this insect because the leaves contain the component 1-deoxynojirimycin (DNJ). A transcriptomic analysis of eri-silkworm haemolymph was conducted to examine the genes related to different metabolic pathways and to elucidate the molecular mechanism underlying eri-silkworm haemolymph responses to DNJ. Eight hundred sixty-five differentially expressed genes (DEGs) were identified, among which 577 DEGs were up-regulated and 288 DEGs were down-regulated in the 2% DNJ group compared to control (ddH₂O) after 12h. Based on the results of the functional analysis, these DEGs were associated with ribosomes, glycolysis, N-glycan biosynthesis, and oxidative phosphorylation. In particular, according to the KEGG analysis, 138 DEGs were involved in energy metabolism, glycometabolism and lipid metabolism, and the changes in the expression of nine DEGs were confirmed by reverse transcription quantitative PCR (RT-qPCR). Thus, DNJ induced significant metabolic alterations in eri-silkworm haemolymph. These results will lay the foundation for research into the toxic effects of DNJ on eri-silkworm as a model and provide a reference for the exploitation of new drugs in humans.

Biochemical characterization and functional analysis of invertase Bmsuc1 from silkworm, Bombyx mori

Invertase or β-fructofuranosidase (EC 3.2.1.26) belongs to the glycoside hydrolase family 32, which catalyzes the hydrolysis of sucrose into fructose and glucose. Here, we report the biochemical and functional characterization of invertase Bmsuc1 from Bombyx mori. Bmsuc1 showed optimal hydrolysis at pH 7.0-8.0 and its optimum temperature is 50°C using sucrose as substrate. Circular dichroism spectra indicated Bmsuc1 had a primarily β-strand structure. The thermal denaturations transition of Bmsuc1 was a cooperative process with a Tm, ΔH, and ΔS of 53.81±0.12°C, 185.51±0.14KJ/mol and 0.56±0.01KJ/(molK), respectively. Moreover, homology modeling and multi-sequence alignment suggested that Bmsuc1 has a canonical β-propeller fold and one conserved catalytic triad, Asp⁶³-Asp¹⁸¹-Glu²³⁴, which is located in the bottom of the substrate-binding pocket. Bmsuc1 was expressed at high levels in the silk gland at both the transcriptional and translational levels. These expression profiles combined with invertase activity analyses of Bmsuc1 suggested that it might function as a digestive enzyme to hydrolyze sugar in the silk gland lumen. Collectively, these findings expand towards a better understanding of the structure of Bmsuc1 and its function in the silk gland.

Reverse transcriptase sequences from mulberry LTR retrotransposons: characterization analysis

Copia and Gypsy play important roles in structural, functional and evolutionary dynamics of plant genomes. In this study, a total of 106 and 101, Copia and Gypsy reverse transcriptase (rt) were amplified respectively in the Morus notabilis genome using degenerate primers. All sequences exhibited high levels of heterogeneity, were rich in AT and possessed higher sequence divergence of Copia rt in comparison to Gypsy rt. Two reasons are likely to account for this phenomenon: a) these elements often experience deletions or fragmentation by illegitimate or unequal homologous recombination in the transposition process; b) strong purifying selective pressure drives the evolution of these elements through “selective silencing” with random mutation and eventual deletion from the host genome. Interestingly, mulberry rt clustered with other rt from distantly related taxa according to the phylogenetic analysis. This phenomenon did not result from horizontal transposable element transfer. Results obtained from fluorescence in situ hybridization revealed that most of the hybridization signals were preferentially concentrated in pericentromeric and distal regions of chromosomes, and these elements may play important roles in the regions in which they are found. Results of this study support the continued pursuit of further functional studies of Copia and Gypsy in the mulberry genome.

Proteomics Provides Insight into the Interaction between Mulberry and Silkworm

Mulberry leaves have been selected as a food source for the silkworm (Bombyx mori) for over 5000 years. However, the interaction mechanisms of mulberry-silkworm remain largely unknown. We explore the interaction between mulberry and silkworm at the protein level. Total proteins were extracted from mulberry leaves and silkworm feces on day 5 of the fifth larval instar and analyzed on shotgun liquid chromatography-tandem mass spectrometry, respectively. In total, 2076 and 210 foliar proteins were identified from mulberry leaves and silkworm feces, respectively. These proteins were classified into four categories according to their subcellular location: chloroplast proteins, mitochondrial proteins, secretory-pathway proteins, and proteins of other locations. Chloroplast proteins accounted for 68.3% in mulberry leaves but only 23.2% in the feces. In contrast, secretory-pathway proteins had low abundance in mulberry leaves (7.3%) but were greatly enriched to the largest component in the feces (60.1%). Most of the foliar secretory-pathway proteins in the feces were found to be resistant to silkworm feeding by becoming involved in primary metabolite, proteinase inhibition, cell-wall remodeling, redox regulation, and pathogen-resistant processes. On the contrary, only six defensive proteins were identified in the fecal chloroplast proteins including two key proteins responsible for synthesizing jasmonic acid, although chloroplast proteins were the second largest component in the feces. Collectively, the comparative proteomics analyses indicate that mulberry leaves not only provide amino acids to the silkworm but also display defense against silkworm feeding, although the silkworm grows very well by feeding on mulberry leaves, which provides new insights into the interactions between host-plant and insect herbivores.

Chemical profile and defensive function of the latex of Euphorbia peplus

Plant latex is an endogenous fluid secreted from highly specialized laticifer cells and has been suggested to act as a plant defense system. The chemical profile of the latex of Euphorbia peplus was investigated. A total of 13 terpenoids including two previously unknown diterpenoids, (2S*,3S*,4R*,5R*,6R*,8R*,l1R*,13S*,14S*,15R*, 16R*)-5,8,15-triacetoxy-3-benzoyloxy-11,16-dihydroxy-9-oxopepluane and (2R*,3R*, 4S*,5R*,7S*,8S*,9S*,l3S*,14S*,15R*)-2,5,8,9,14-pentaacetoxy-3-benzoyloxy-15-hydroxy-7-isobutyroyloxyjatropha-6(17),11E-diene), ten known diterpenoids, and a known acyclic triterpene alcohol peplusol, were identified, using HPLC and UPLC-MS/MS analyses and through comparison with the authentic compounds isolated from the whole plant. The diterpenoids exhibited significant antifeedant activity against a generalist plant-feeding insect, the cotton bollworm (Helicoverpa armigera), with EC₅₀ values ranging from 0.36 to 4.60 μg/cm². In particular, (2R*,3R*,4S*,5R*,7S*,8S*,9S*,l3S*,14S*,15R*)-2,5,9,14-tetraacetoxy-3-benzoyloxy-8,15-dihydroxy-7-isobutyroyloxyjatropha-6(17),11E-diene and (2R*,3R*, 4S*,5R*,7S*,8S*,9S*,l3S*,14S*,15R*)-2,5,14-triacetoxy-3-benzoyloxy-8,15-dihydroxy-7-isobutyroyloxy-9-nicotinoyloxyjatropha-6(17),11E-diene had EC₅₀ values of 0.36 and 0.43 μg/cm², respectively, which were approximately 7-fold more potent than commercial neem oil (EC₅₀ = 2.62 μg/cm²). In addition, the major peplusol showed obvious antifungal activity against three strains of agricultural phytopathogenic fungi, Rhizoctonia solani, Colletotrichum litchi and Fusarium oxysporum f. sp. niveum. The results indicated that terpenoids in the latex of E. peplus are rich and highly diversified, and might function as constitutive defense metabolites against insect herbivores and pathogens for the plant.