Dual function of a bumblebee (Bombus ignitus) serine protease inhibitor that acts as a microbicidal peptide and anti-fibrinolytic venom toxin

Animal-derived peptides from Traditional Chinese medicines: medicinal potential, mechanisms, and prospects

ETHNOPHARMACOLOGICAL RELEVANCE

Animal-derived traditional Chinese medicines have a long-standing history in Chinese medicine, which exhibit unique efficacy due to similar structure and function with human tissue. As the major types of constituents that accounted for a relatively high proportion of animal-derived TCMs, peptides with molecular weight between 100 Da and hundreds of thousands of kDa have caught wide attention due to their outstanding bioavailability and excellent specificity.

AIM OF THE STUDY

This review aims to comprehensively delve into the up-to-date research progress in their pharmacology, mechanism, sequence composition, and therapeutic application, laying a solid foundation for future clinical treatment and scientific research.

MATERIALS AND METHODS

Relevant information on the peptides from animal-derived TCMs was collected from scientific literature databases including PubMed, CNKI, literature sources (Ph.D. and M.Sc. dissertations), and Web of Science by using the keywords "Peptides", "Animal", and "TCMs" for gradual screening in the past 30 years.

RESULTS

To date, the peptides from 27 kinds of animal-derived TCMs have been systematically combed. Their pharmacological activity and underlying mechanisms on multiple systems (nervous, circulatory, skeletal, and immune), as well as anti-tumor, antioxidative, and antimicrobial effects, have been sorted out. Besides, the potential safety issues and deficiencies (low bioavailability, imperfect quality management, and toxicity of raw materials) have also been pointed out.

CONCLUSIONS

Comprehensive analysis showed that low development and resource waste accompanied by the inadequate report about the pharmacological activity of most peptides from animal-derived TCMs make it have good research prospects. Although a breakthrough in the field of healthcare products has been made, the development potential for clinical products that bring surprising turnaround will be obtained if the above-mentioned confusions and current needs (improve identification technology and design reasonable dosage forms) are implemented.

A venom serpin from the assassin bug Sycanus croceovittatus exhibiting inhibitory effects on melanization, development, and insecticidal activity towards its prey

Serine protease inhibitors (SPIs) have been identified as main common components in the venom of the predatory bugs, while their functional roles remain unexplored. In this study, we identified 35 SPI genes belonging to three subfamilies of serpin, canonical SPI, and A2M in genome of the assassin bug, Sycanus croceovittatus. The amino acid sequences of these SPI genes reveal conserved functional regions, albeit with mutations or deletions at certain active site residues. Transcriptomic and qPCR analyses of gene expression patterns in various tissues across developmental stages indicate that most SPI genes exhibit high expression levels in venom apparatus, suggesting their role as venom proteins. Notably, the ScSPI5 gene from the serpin class was found to be most abundantly expressed in all three distinct venom glands, indicating its significant role as a venomous protein. Functional characterization demonstrated that this venom serpin effectively inhibits trypsin activity in vitro and suppresses phenoloxidase activity, thereby blocking hemolymph melanization in preys, including Spodoptera frugiperda, Achelura yunnanensis, and Tenebrio molitor. When ingested, it reduces the larval and pupal weight of the fall armyworm by impeding trypsin activity in the midgut. Upon injection, ScSPI5 exhibits a dose-dependent insecticidal effect against T. molitor, with an LD50 of 5.6 ± 1.1 μg/g. These findings elucidate the specific functions of SPIs in the venom of predatory bugs, enhancing our understanding of their predation efficiency, and highlighting the potential application of venomous SPIs as protease inhibitors in pest management strategies.

Insights from Melipona bicolor hybrid genome assembly: a stingless bee genome with chromosome-level scaffold

BACKGROUND

The highly eusocial stingless bees are crucial pollinators of native and agricultural ecosystems. Nevertheless, genomic studies within this bee tribe remain scarce. We present the genome assembly of the stingless bee Melipona bicolor. This bee is a remarkable exception to the typical single-queen colony structure, since in this species, multiple queens may coexist and share reproductive duties, resulting in genetically diverse colonies with weak kinship connections. As the only known genuinely polygynous bee, M. bicolor's genome provides a valuable resource for investigating sociality beyond kin selection.

RESULTS

The genome was assembled employing a hybrid approach combining short and long reads, resulting in 241 contigs spanning 259 Mb (N50 of 6.2 Mb and 97.5% complete BUSCOs). Comparative analyses shed light on some evolutionary aspects of stingless bee genomics, including multiple chromosomal rearrangements in Melipona. Additionally, we explored the evolution of venom genes in M. bicolor and other stingless bees, revealing that, apart from two genes, the conserved repertoire of venom components remains under purifying selection in this clade.

CONCLUSION

This study advances our understanding of stingless bee genomics, contributing to the conservation efforts of these vital pollinators and offering insights into the evolutionary mechanisms driving their unique adaptations.

Ingestion of heat-killed pathogens confers transgenerational immunity to the pathogens via the vitellogenin-hypopharyngeal gland axis in honeybees

Honeybee diseases are a serious threat to beekeeping and pollination. Transgenerational immune priming (TGIP) has been attracting increasing attention as a promising strategy to protect honeybee colonies from infections. This study investigated whether feeding honeybees (Apis mellifera) with a heat-killed pathogen cocktail can provide them with transgenerational immunity to these pathogens. We found that vitellogenin (Vg) and defensin-1 were highly upregulated in nurse bees upon feeding them with a cocktail of heat-killed Ascosphaera apis and Paenibacillus larvae (A + P cocktail). Pathogen-pattern-recognition receptor genes in the Toll signaling pathway were upregulated in nurse bees upon ingestion of the A + P cocktail. In the nurse bees of the hives supplied with the A + P cocktail, Vg was upregulated in the fat body, and the defensin-1 expression and Vg uptake in the hypopharyngeal glands were induced. Consequently, the major proteins in royal jelly were upregulated. In addition, defensin-1 was upregulated in the queen larvae and young worker larvae in these hives. In correlation, the young worker larvae showed high pathogen resistance to P. larvae infection. Thus, our findings imply that introduction of a heat-killed pathogen cocktail into hives is an efficient strategy for conferring honeybees with social immunity through TGIP.

Identification of waprin and its microbicidal activity: A novel protein component of honeybee (Apis mellifera) venom

Bee venom is a rich source of biologically and pharmacologically active proteins. Waprin is a protein component of venoms; however, waprin has yet to be identified in bee venom. Moreover, the biological functions of waprin in venoms remain poorly characterized. Thus, in this study, we have identified and characterized waprin: a novel protein component from the venom of honeybees (Apis mellifera). The waprin in A. mellifera venom (Amwaprin) was found to consist of an 80-amino acid mature peptide, in which the whey acidic protein domain contains four conserved disulfide bonds. We discovered the presence of the Amwaprin protein in secreted venom by using an antibody against recombinant Amwaprin produced in baculovirus-infected insect cells. Recombinant Amwaprin exhibited inhibitory activity against microbial serine proteases and elastases but not thrombin or plasmin. It recognized carbohydrates in the microbial cell wall molecules and bound to the live microbial surfaces. The binding action of Amwaprin produced its microbicidal activity by inducing structural damage to bacterial and fungal cell walls. In addition, recombinant Amwaprin is heat-stable and contains no hemolytic activity. These findings demonstrate that Amwaprin acts as a microbicidal and anti-elastolytic agent.

Antimicrobial Activity of Apidermin 2 from the Honeybee Apis mellifera

Apidermins (APDs) are known as structural cuticular proteins in insects, but their additional roles are poorly understood. In this study, we characterized the honeybee, Apis mellifera, APD 2 (AmAPD 2), which displays activity suggesting antimicrobial properties. In A. mellifera worker bees, the AmAPD 2 gene is transcribed in the epidermis, hypopharyngeal glands, and fat body, and induced upon microbial ingestion. Particularly in the epidermis of A. mellifera worker bees, the AmAPD 2 gene showed high expression and responded strongly to microbial challenge. Using a recombinant AmAPD 2 peptide, which was produced in baculovirus-infected insect cells, we showed that AmAPD 2 is heat-stable and binds to live bacteria and fungi as well as carbohydrates of microbial cell wall molecules. This binding action ultimately induced structural damage to microbial cell walls, which resulted in microbicidal activity. These findings demonstrate the antimicrobial role of AmAPD 2 in honeybees.