Low-concentration exogenous 3-indoleacetic acid improves fruit-setting rate of Marsdenia tenacissima by inhibiting the expression of embryo abortion-related genes

Marsdenia tenacissima is a medicinal plant characterized by many flowers, few fruits, and a low fruit-setting rate. Exogenous auxins can improve the fruit-setting rate of plants; however, their impacts on M. tenacissima and regulatory mechanisms remain unclear. In this study, we conducted a field experiment to determine the fruit-setting rate, seed-setting rate, fruit size, and changes in transcriptional expression of related genes by spraying 10 and 50 mg·L-1 of 3-indoleacetic acid (IAA). The control plants were sprayed with distilled water. Our results indicated that the fruit-setting rate was 0.15 when treated with 10 mg·L-1 of IAA, which was 2.76-fold higher than that of the control. Compared with that of the control, the number of differentially expressed genes (DEGs) regulated by 10 mg·L-1 of IAA was 28.6-fold higher than that regulated by 50 mg·L-1 of IAA. These DEGs were closely related to hormone metabolism and fruit development. By transcriptome analysis, spraying 10 mg·L-1 of IAA increased the expressions of STP6, MYB17, and LAX3 and reduced those of CXE18, ILR1-like 3, and SAUR50; this possibly affected the ovule, embryo, and fruit development, thereby elevating the fruit-setting rate of M. tenacissima. Our results indicated that low IAA concentration increased the fruit-setting rate of M. tenacissima, providing theoretical and practical support for promoting the seed yield of M. tenacissima.

Characteristics of heavy metal accumulation and risk assessment in understory Panax notoginseng planting system

Yunnan Province is the main planting area of the precious Chinese herbal medicines (CHM) Panax notoginseng; however, it locates the geological area with high soil heavy metals in China. The frequent land replacement due to continuous cropping obstacles and excessive application of chemicals makes P. notoginseng prone to be contaminated by heavy metals under the farmland P. notoginseng (FPn) planting. To overcome farmland shortage, understory P. notoginseng (UPn) was developed as a new ecological planting model featured by no chemicals input. However, this newly developed planting system requires urgently the soil-plant heavy metal characteristics and risk assessment. This study aimed to evaluate the pollution status of eight heavy metals in the tillage layer (0-20 cm), subsoil layer (20-40 cm) and the plants of UPn in Lancang County, Yunnan Province. Pollution index (Pi) showed that the contamination degree of heavy metals in the tillage layer and subsoil layer was Cd > Pb > Ni > Cu > Zn > Cr > Hg > As and Pb > Cd > Cu > Ni > Cr > Hg > Zn > As, respectively. Potential ecological risk index (PERI) for the tillage layer and subsoil layer was slight and middle, respectively. The exceeding standard rate of Cd, As, Pb, Hg, Cu in the UPn roots was 5.33%, 5.33%, 13.33%, 26.67% and 1.33%, respectively, while only Cd and Hg in the UPn leaves exceeded the standard 10% and 14%, respectively. The enrichment abilities of Cd and Hg in the roots and leaves of UPn were the strongest, while that of Pb was the weakest. The Hazard index (HI) and target hazard quotient (THQ) of eight heavy metals in the roots and leaves of UPn were less than 1.Therefore, our results prove that Upn has no human health risk and provide a scientific basis for the safety evaluation and extension of UPn.

[The association between Helicobacter pylori virulence factor genotypes and gastroduodenal diseases in children]

Objective: To investigate the association between Helicobacter pylori (Hp) virulence factor genotypes and the degree and activity of gastric mucosa pathological changes in pediatric gastroduodenal diseases. Methods: This retrospective cohort study was conducted from May 2020 to October 2020. The frozen strains of Hp, which were cultured with the gastric mucosa of 68 children with gastroscopy confirmed gastroduodenal diseases who visited the children's hospital of Zhejiang University School of Medicine from April 2012 to December 2014, were resuscitated. After extracting DNA from these Hp strains, PCR amplification and agarose gel electrophoresis were performed to determine the detection rate of cytotoxin-associated protein A (cagA),vacuolating cytotoxin A (vacA)(s1a、s1b/s2,m1/m2), outer inflammatory protein A (oipA),blood group antigen binding adhesin (babA),duodenal ulcer promoting protein A (dupA) genes; oipA genes were sequenced to determine the gene status. The patients were divided into different groups according to the findings of gastroscopy and gastric mucosa pathology. The detection rates of various virulence factor genotypes among different groups were compared using χ2 tests or Fisher's exact tests. Results: The 68 Hp strains all completed genetic testing. According to the diagnostic findings of gastroscopy, the 68 cases were divided into 47 cases of superficial gastritis and 21 cases of peptic ulcer. Regarding the pathological changes of gastric mucosa, 8 cases were mild, and 60 cases were moderate and severe according to the degree of inflammation; 61 cases were active and 7 cases inactive according to the activity of inflammation. The overall detection rates of cagA, vacA, vacA s1/m2, functional oipA, babA2, and dupA virulence factor genes were 100% (68/68), 100% (68/68), 94% (64/68), 99% (67/68), 82% (56/68), and 71% (48/68), respectively. In the superficial gastritis group, their detection rates were 100% (47/47), 100% (47/47), 96% (45/47), 98% (46/47), 81% (38/47), and 70% (33/47), respectively; in the peptic ulcer group, their detection rates were 100% (21/21), 100% (21/21), 90% (19/21), 100% (21/21), 86% (18/21), and 71% (15/21), respectively. There was no statistically significant difference between the two groups (all P>0.05). In the mild gastric mucosa inflammation group, the detection rates of the above six genotypes were 8/8, 8/8, 8/8, 7/8, 7/8, and 5/8, respectively; and in the moderate to severe inflammation groups, the detection rates were 100% (60/60), 100% (60/60), 93% (56/60), 100% (60/60), 82% (49/60), and 72% (43/60), respectively, with no statistically significant difference between the two groups (all P>0.05). In the active inflammation group, the detection rate of six genotypes were 100% (61/61), 100% (61/61), 93% (57/61), 98% (60/61), 82% (50/61), and 72% (44/61), respectively; and in the inactive inflammation group, they were 7/7, 7/7, 7/7, 7/7, 6/7, and 4/7, respectively. Again, there was no statistically significant difference between the two groups (all P>0.05). There was no statistically significant difference in the detection rate of combinations of 4 or 5 virulence factor genes among the different groups (all P>0.05). Conclusions: CagA, vacA, vacA s1/m2, functional oipA, babA2, and dupA genes are not associated with superficial gastritis and peptic ulcer in children, or with the degree and activity of gastric mucosa pathological inflammation. Different gene combinations of cagA, vacA, oipA, babA2, and dupA have no significant effects on predicting the clinical outcome of Hp infection in children.

[The relationship between genetic polymorphism of CYP2C19 and the efficacy of Helicobacter pylori eradication therapy in children]

Objective: To investigate the relationship between genetic polymorphisms of cytochrome P450 2C19 (CYP2C19) and the efficacy of Helicobacter pylori (Hp) eradication therapy in children. Methods: The retrospective cohort study was conducted on 125 children with gastroscopy and positive rapid urease test (RUT) from September 2016 to December 2018 who presented to the Children's Hospital of Zhejiang University School of Medicine due to gastrointestinal symptoms including nausea, vomiting, abdominal pain, bloating, acid reflux, heartburn, chest pain, vomiting blood and melena. Hp culture and drug susceptibility test were carried out with gastric antrum mucosa before treatment. All the patients completed 2 weeks of standardized Hp eradication therapy and had ¹³C urea breath test 1 month after that, which was used to evaluate the curative effect. The DNA of gastric mucosa after RUT was analyzed and CYP2C19 gene polymorphism was detected. Children were grouped according to metabolic type. Combined with the results of Hp culture and drug susceptibility, the relationship between CYP2C19 gene polymorphism and the efficacy of Hp eradicative treatment was analyzed in children. Chi square test was used for row and column variables, and Fisher exact test was used for comparison between groups. Results: One hundred and twenty five children were enrolled in the study, of whom 76 were males and 49 females. The genetic polymorphism of CYP2C19 in these children found poor metabolizer (PM) of 30.4% (38/125), intermediate metabolizer (IM) of 20.8% (26/125), normal metabolizer (NM) of 47.2% (59/125), rapid metabolizer (RM) of 1.6% (2/125), and ultrarapid metabolizer (UM) of 0. There were statistically significant in positive rate of Hp culture among these groups (χ²=124.00, P<0.001). In addition, the successful rates of Hp eradication in PM, IM, NM and RM genotypes were 84.2% (32/38), 53.8% (14/26), 67.8% (40/59), and 0, respectively, with significant differences (χ²=11.35, P=0.010); those in IM genotype was significantly lower than that in PM genotype (P=0.011). With the same standard triple Hp eradicative regimen, the successful rate of Hp eradication for IM type was 8/19, which was lower than that of PM (80.0%, 24/30) and NM type (77.3%, 34/44) (P=0.007 and 0.007, respectively). There was a significant difference in the efficacy of Hp eradication treatment among different genotypes (χ²=9.72, P=0.008). According to the clarithromycin susceptibility result, the successful rate of Hp eradication treatment for IM genotype was 4/15 in the sensitive group and 4/4 in the drug-resistant group (χ²=6.97, P=0.018). Conclusions: The genetic polymorphism of CYP2C19 in children is closely related to the efficacy of Hp eradication treatment. PM has a higher successful rate of eradication treatment than the other genotypes.

Attapulgite amendment favors the utilization of high cadmium-contaminated soil for Erigeron breviscapus cultivation

A practical measure of soil pollution can effectively control the utilization of contaminated soil during the remediation process. In this study, Erigeron breviscapus was used as the experimental material. Soil polluted with high concentrations of cadmium (Cd) was used to study the effects of different doses of attapulgite (AP) (0, 10, 20, and 40 kg^-1 for AP0, AP10, AP20, and AP40, respectively) on the yield and quality of E. breviscapus (as measured by scutellarin), as well as soil remediation. The results showed that the yield and scutellarin content of E. breviscapus decreased by 33.4% and 78.9%, respectively, in soil contaminated with high concentrations of Cd (AP0) compared with the control soil (without Cd added). Moreover, the yield increased by 48.0% and 10.6% in AP20 and AP40, respectively, compared with AP0, and the scutellarin content increased by a factor of 2.35-2.41 in AP10, AP20, and AP40. Compared with AP0, the soil Cd content decreased by 22.5-26.2% in AP10, AP20, and AP40 and the available Cd content and acid-extractable Cd fraction in the soil also decreased. The catalase, peroxidase, superoxide dismutase activities, chlorophyll, and Fe²⁺ content were increased in AP10, AP20, and AP40, leading to an increased yield and scutellarin content. Overall, AP20 had the best effect on the yield, quality of E. breviscapus, and soil remediation. This study provides a practical measure to consider for concurrent benefits of pollution remediation and utilization of Cd-contaminated soil.

Effects of polyethylene and biodegradable microplastics on photosynthesis, antioxidant defense systems, and arsenic accumulation in maize (Zea mays L.) seedlings grown in arsenic-contaminated soils

Arsenic (As) and microplastic (MP) co-exposure is a major environmental problem in terrestrial ecosystems. Polyethylene and biodegradable plastics decompose into MP particles under microbial-mediated and weathering conditions. However, the effects of MP particles on physiological responses and As accumulation in maize have not been thoroughly explored. In this study, the effects of polyethylene microplastic particles (PEMPs) and biodegradable microplastic particles (BPMPs) on As accumulation, growth and physio-biochemical performance of maize seedlings (Zea mays L.) in As-contaminated soil were investigated. Our study showed that 10 % PE reduced As content in maize seedlings leaves (roots) by 41.19(34.53) μg kg^-1, compared to the control. The 10 % BP reduced As content in maize seedlings leaves (roots) by 64.24 (57.27) μg kg^-1. 10 % PE (10 % BP) reduced maize seedlings leaf area, total chlorophyll content and photosynthetic rate by 5.05 % (21.68 %), 44.98 % (57.12 %) and 65.29 % (77.89 %) and increased H₂O₂ content by 38.04 % (179.6 %), respectively. The antioxidant defense system of maize seedlings leaves was damaged by PEMPs and As co-exposure. Maize seedlings has adapted to stress by regulating antioxidant enzyme activity and the AsA-GSH cycle under BPMPs and As co-exposure. This study provides new insights into the effects of PEMPs and BPMPs on phytotoxicity and As accumulation in As-contaminated soils. Preliminarily data suggests that BPMPs may exhibit greater toxic effects on maize seedlings than PEMPs, which warrants further exploration.

Marsdenia tenacissima genome reveals calcium adaptation and tenacissoside biosynthesis

Marsdenia tenacissima is a medicinal plant widely distributed in the calcium-rich karst regions of southwest China. However, the lack of a reference genome has hampered the implementation of molecular techniques in its breeding, pharmacology and domestication. We generated the chromosome-level genome assembly in Apocynaceae using combined SMRT sequencing and Hi-C. The genome length was 381.76 Mb, with 98.9% of it found on 11 chromosomes. The genome contained 222.63 Mb of repetitive sequences and 21 899 predicted gene models, with a contig N50 of 6.57 Mb. Phylogenetic analysis revealed that M. tenacissima diverged from Calotropis gigantea at least 13.43 million years ago. Comparative genomics showed that M. tenacissima underwent ancient shared whole-genome duplication. This event, together with tandem duplication, contributed to 70.71% of gene-family expansion. Both pseudogene analysis and selective pressure calculations suggested calcium-related adaptive evolution in the M. tenacissima genome. Calcium-induced differentially expressed genes (DEGs) were mainly enriched in cell-wall-related processes. Domains (e.g. Fasciclin and Amb_all) and cis-elements (e.g. MYB and MYC) frequently occurred in the coding and promoter regions of cell-wall DEGs, respectively, and the expression levels of these genes correlated significantly with those of calcium-signal-related transcription factors. Moreover, calcium addition increased tenacissoside I, G and H contents. The availability of this high-quality genome provides valuable genomic information for genetic breeding and molecular design, and lends insights into the calcium adaptation of M. tenacissima in karst areas.

Sulfur fertiliser enhancement of Erigeron breviscapus (Asteraceae) quality by improving plant physiological responses and reducing soil cadmium bioavailability

Erigeron breviscapus (Vant.) Hand.-Mazz. is an important medicinal plant; however, its quality is severely diminished by cadmium (Cd) pollution. Sulfur fertilisation can improve the production and application of E. breviscapus. This study examined Cd stress alleviation in the soil-plant system and determined the plant growth response after the application of sulfur fertiliser. The soil Cd concentration used in the treatments was 100 g·kg^-1, and the sulfur fertiliser application rates were 0.1, 0.2, and 0.3 g·kg^-1. Using pot experiments, we explored the impacts of high, medium, and low amounts of sulfur fertiliser on Cd accumulation and the quality and activity of E. breviscapus. The results showed that the application of sulfur fertiliser promoted Cd transformation to residual Cd under oxidation conditions, reducing Cd accumulation in E. breviscapus. Throughout the growth period, the application of sulfur fertiliser increased the soluble protein content and antioxidant enzyme activity, which alleviated Cd toxicity. The net photosynthetic rate, transpiration rate, intercellular CO₂ concentration, chlorophyll level, and leaf width increased significantly. The biomass content of E. breviscapus also increased. Sulfur fertiliser improves the quality of herbaceous medicinal plants by reducing Cd accumulation and increasing scutellarin, chlorogenic, isochlorogenic acid B, and isochlorogenic acid C contents. A reasonable application of sulfur fertiliser is essential for improving E. breviscapus quality. This study provides a new method to reduce the ecological risk of planting herbaceous medicinal plants in Cd-contaminated soil.

Gene fusion as an important mechanism to generate new genes in the genus Oryza

Background

Events of gene fusion have been reported in several organisms. However, the general role of gene fusion as part of new gene origination remains unknown.

Results

We conduct genome-wide interrogations of four Oryza genomes by designing and implementing novel pipelines to detect fusion genes. Based on the phylogeny of ten plant species, we detect 310 fusion genes across four Oryza species. The estimated rate of origination of fusion genes in the Oryza genus is as high as 63 fusion genes per species per million years, which is fixed at 16 fusion genes per species per million years and much higher than that in flies. By RNA sequencing analysis, we find more than 44% of the fusion genes are expressed and 90% of gene pairs show strong signals of purifying selection. Further analysis of CRISPR/Cas9 knockout lines indicates that newly formed fusion genes regulate phenotype traits including seed germination, shoot length and root length, suggesting the functional significance of these genes.

Conclusions

We detect new fusion genes that may drive phenotype evolution in Oryza. This study provides novel insights into the genome evolution of Oryza.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13059-022-02696-w.

AB1426 PREDICTORS OF RHEUMATIC TOXICITIES OF IMMUNE CHECKPOINT INHIBITORS AND CANCER OUTCOMES IN PATIENTS WITH ADVANCED MELANOMA

Background

Immune checkpoint inhibitors (ICIs) including monoclonal antibodies to PD-1 and CTLA-4 have activity across various cancers. Dedicated cohort studies have examined the epidemiology and clinical course of rheumatic toxicities (1–3) and the effect of pre-existing autoimmune disease has been explored (4), with limited assessment of the effect of non-immune mediated rheumatic disease (3). A positive association between ICI-induced rheumatic disease and favourable cancer outcomes has been suggested (1,2), although derived from heterogenous cancer populations.

Objectives

To identify risk factors for the development of ICI-induced rheumatic disease and predictors of cancer outcomes in patients with advanced melanoma.

Methods

A single-centre observational study of patients with stage III or IV melanoma receiving all available ICI therapies, who completed a for-purpose questionnaire to capture rheumatic symptoms and risk factors upon recruitment and at 12-months. Symptom severity was assessed according to patient reported measures such as visual analogue scale (VAS) scores for pain. Clinical details were extracted from patients’ medical records. Predictors of rheumatic toxicities and cancer outcomes were identified through regression analysis.

Results

Amongst 147 eligible patients, the prevalence of new or worsening rheumatic symptoms was 32.5% at recruitment and 21% at 12 months. The incidence of documented arthralgia, inflammatory arthritis and PMR-like syndrome was 39.5%, 5.4% and 3.4% respectively. Binary logistic regression identified pre-existing symptomatic rheumatic disease, including non-immune mediated rheumatic disease, as the primary risk factor for developing rheumatic toxicities (OR 3.161). Continuation of ICI therapy (OR 16.52), followed by rheumatic toxicities (OR = 4.368) were predictors of favourable tumour response.

Conclusion

Rheumatic toxicities of ICI therapy commonly affect patients with melanoma and are more likely to occur in patients with pre-existing autoimmune and non-immune mediated rheumatic disease. Continuation of ICI therapy improves cancer outcomes and can be facilitated by early detection of rheumatic symptoms using patient reported outcome measures.

Table 1.

Bivariate logistic regression of predictors of patient-reported rheumatic toxicity. Sig., Significance; OR, Odds ratio; CI, confidence interval; BRAF/MEK, BRAF and MEK inhibitors; PD-1, Programmed Cell Death protein – 1; CTLA-4, Cytotoxic T-lymphocyte-associated protein.

Figure 1.

A) Receiver-operator curve for accuracy of binary logistic regression model clinician-recorded rheumatic disease. (B) Area under receiver-operator curve. Test result variable(s): predicted probability. AUROC, Area Under Receiver-Operator Curve; Std. Error, Standard Error; Sig., Significance.

(a) Under the nonparametric assumption

(b) Null hypothesis: true area = 0.5

References

[1]Kostine M, Rouxel L, Barnetche T, Veillon R, Martin F, Dutriaux C, et al. Rheumatic disorders associated with immune checkpoint inhibitors in patients with cancer-clinical aspects and relationship with tumour response: a single-centre prospective cohort study. Ann Rheum Dis. 2018;77(3):393–8.

[2]Braaten TJ, Brahmer JR, Forde PM, Le D, Lipson EJ, Naidoo J, et al. Immune checkpoint inhibitor-induced inflammatory arthritis persists after immunotherapy cessation. Ann Rheum Dis. 2019;332–8.

[3]Buder-Bakhaya K, Benesova K, Schulz C, Anwar H, Dimitrakopoulou-Strauss A, Weber TF, et al. Characterization of arthralgia induced by PD-1 antibody treatment in patients with metastasized cutaneous malignancies. Cancer Immunol Immunother. 2018;67(2):175–82.

[4]Menzies AM, Johnson DB, Ramanujam S, Atkinson VG, Wong ANM, Park JJ, et al. Anti-PD-1 therapy in patients with advanced melanoma and preexisting autoimmune disorders or major toxicity with ipilimumab. Ann Oncol. 2017;28(2):368–76.

Disclosure of Interests

Alana Bruce: None declared, Alexander Menzies Consultant of: A.M.M. has participated in advisory boards for BMS, MSD, Novartis, Roche, Pierre-Fabre, Georgina Long Consultant of: GVL is consultant advisor for Aduro Biotech Inc, Agenus Inc, Amgen Inc, Array Biopharma inc, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb, Evaxion Biotech A/S, Hexel AG, Highlight Therapeutics S.L., Merck Sharpe & Dohme, Novartis Pharma AG, OncoSec, Pierre Fabre, QBiotics Group Limited, Regeneron Pharmaceuticals Inc, Specialised Therapeutics Australia Pty Ltd., Brian Fernandes: None declared, Fredrick Joshua Consultant of: F.J. has performed clinical trials and participated in advisory boards for Abbvie, Pfizer, Novartis, Sanofi, Eli Lily and Roche

High quality genome of Erigeron breviscapus provides a reference for herbal plants in Asteraceae

Erigeron breviscapus is an important medicinal plant in Compositae and the first species to realize the whole process from the decoding of the draft genome sequence to scutellarin biosynthesis in yeast. However, the previous low‐quality genome assembly has hindered the optimization of candidate genes involved in scutellarin synthesis and the development of molecular‐assisted breeding based on the genome. Here, the E. breviscapus genome was updated using PacBio RSII sequencing data and Hi‐C data, and increased in size from 1.2 Gb to 1.43 Gb, with a scaffold N50 of 156.82 Mb and contig N50 of 140.95 kb, and a total of 43,514 protein‐coding genes were obtained and oriented onto nine pseudo‐chromosomes, thus becoming the third plant species assembled to chromosome level after sunflower and lettuce in Compositae. Fourteen genes with evidence for positive selection were identified and found to be related to leaf morphology, flowering and secondary metabolism. The number of genes in some gene families involved in flavonoid biosynthesis in E. breviscapus have been significantly expanded. In particular, additional candidate genes involved in scutellarin biosynthesis, such as flavonoid‐7‐O‐glucuronosyltransferase genes (F7GATs) were identified using updated genome. In addition, three candidate genes encoding indole‐3‐pyruvate monooxygenase YUCCA2 (YUC2), serine carboxypeptidase‐like 18 (SCPL18), and F‐box protein (FBP), respectively, were identified to be probably related to leaf development and flowering by resequencing 99 individuals. These results provided a substantial genetic basis for improving agronomic and quality traits of E. breviscapus, and provided a platform for improving other draft genome assemblies to chromosome‐level.

Transcriptomic response to cold of thermophilous medicinal plant Marsdenia tenacissima

Extracts from Marsdenia tenacissima, involving tenacissoside H, I and G, have been used as remedies of cancer, inflammation and asthma. Low temperature serves as one of the main factors constrain the planting expansion and quality of M. tenacissima, but its functional mechanism has been known scarcely for the lack of genomic information and transcriptional profile. Here we investigated the transcriptomic responses of M. tenacissima under cold stress to gain insight into the molecular mechanism of low temperature sensitivity. Total RNAs were collected from samples obtained at 4-time points (after 0, 3, 6 and 48 h cold treatments with 4 °C, respectively), then used for library construction and sequenced on the Illumina Hiseq™ 4000 platform. Passing quality assessments, 500794 transcripts, and 206137 unigenes were de novo assembly out in Trinity v2.4.0, holding contig N50 of 2566 bp and unigene mean length of 754 bp. 44.20% of assembled unigenes were annotated to the well-known public protein database on a basis of sequence similarity. Using statistical comparison of the fragments per kilo base of transcript per million reads mapped (FPKM) values between conditions, 6082 group-specific differentially expressed genes (DEGs) were identified and considered as cold-responsive genes, which contained copious transcription factors and active secondary metabolism. Among them, 43 unigenes were constantly up-regulated expression along with cold time, which mainly implicated in the biosynthesis of secondary metabolites, carbon metabolism, RNA and DNA metabolism. Conversely, 21 unigenes involved in photosynthesis, cell wall, protein degradation, and transporters were downregulated continually with cold timescale. Experimentally, MtEF1α was chosen as the best housekeeping gene. Functional enrichments found that damaging of cold stress on M. tenacissima may be ascribed to inability of photosynthesis, ribsome processing, flavonoid biosynthesis and terpenoids degradation. Correlation analysis between cold induced transcription factors and tenacissoside biosynthesis-related genes indicated that 3β-HSD significant positively correlated with bHLH51, and 4-MSO with NF-YB, GRAS3, Trihelix, FAR1, MYB60, MYBS1, bZIP43. Further promoter clone found MYB-binding site in the promoter of 4-MSO. In view of the reported cold tolerance of MYB60, it is recommended as a potential candidate suitable for future molecular design of exaptation cultivation with high bioactive constituents.

Engineering yeast for the production of breviscapine by genomic analysis and synthetic biology approaches

The flavonoid extract from Erigeron breviscapus, breviscapine, has increasingly been used to treat cardio- and cerebrovascular diseases in China for more than 30 years, and plant supply of E. breviscapus is becoming insufficient to satisfy the growing market demand. Here we report an alternative strategy for the supply of breviscapine by building a yeast cell factory using synthetic biology. We identify two key enzymes in the biosynthetic pathway (flavonoid-7-O-glucuronosyltransferase and flavone-6-hydroxylase) from E. breviscapus genome and engineer yeast to produce breviscapine from glucose. After metabolic engineering and optimization of fed-batch fermentation, scutellarin and apigenin-7-O-glucuronide, two major active ingredients of breviscapine, reach to 108 and 185 mg l^-1, respectively. Our study not only introduces an alternative source of these valuable compounds, but also provides an example of integrating genomics and synthetic biology knowledge for metabolic engineering of natural compounds.

Observation of A Raman mode splitting in few layer black phosphorus encapsulated with hexagonal boron nitride

We investigate the impact of encapsulation with hexagonal boron nitride (h-BN) on the Raman spectrum of few layer black phosphorus. The encapsulation results in a significant reduction of the line width of the Raman modes of black phosphorus, due to a reduced phonon scattering rate. We observe a so far elusive peak in the Raman spectra ∼4 cm^-1 above the A mode in trilayer and thicker flakes, which had not been observed experimentally. The newly observed mode originates from the strong black phosphorus inter-layer interaction, which induces a hardening of the surface atom vibration with respect to the corresponding modes of the inner layers. The observation of this mode suggests a significant impact of h-BN encapsulation on the properties of black phosphorus and can serve as an indicator of the quality of its surface.

Paediatric CT dose: a multicentre audit of subspecialty practice in Australia and New Zealand

OBJECTIVES

To evaluate paediatric CT dosimetry in Australia and New Zealand and calculate size-specific dose estimates (SSDEs) for chest and abdominal examinations.

METHODS

Eight hospitals provided data from 12 CT systems for 1462 CTs in children aged 0-15. Imaging data were recorded for eight examinations: head (trauma, shunt), temporal bone, paranasal sinuses, chest (mass) and chest HRCT (high-resolution CT), and abdomen/pelvis (mass/inflammation). Dose data for cranial examinations were categorised by age and SSDEs by lateral dimension. Diagnostic reference ranges (DRRs) were defined by the 25th and 75th percentiles. Centralised image quality assessment was not undertaken.

RESULTS

DRRs for 201 abdominopelvic SSDEs were: 2.8-4.7, 3.6-11.5, 8.5-15.0, 7.6-15, and 10.6-16.2 for the <15 cm, 15-19 cm, 20-24 cm, 25-29 cm and >30 cm groups, respectively. For 147 chest examinations using these body width categories, SSDE DRRs were 2.0-4.4, 3.3-7.9, 4.0-9.4, 4.5-12, and 6.5-12. Kilovoltage peak (kVp), but not AEC or IR, was associated with SSDE (parameter estimate [standard error]: 0.12 (0.03); p < 0.0001).

CONCLUSIONS

Australian and New Zealand paediatric CT DRRs and abdominal SSDEs are comparable to international data. SSDEs for chest examinations are proposed. Dose variations could be reduced by adjusting kVp.

KEY POINTS

• SSDEs can be calculated for all patients, CT systems, and practices • Kilovoltage peak (kVp) has the greatest association with dose in similar-sized patients • Paediatric DRRs for CT are now available for use internationally.

Wearing a crotch strap on a correctly fitted lifejacket improves lifejacket performance

Wearing a lifejacket when immersed in water should support the wearer, maintaining their airway clear of the water. It is proposed that a retention system would improve airway protection by improving retention of the lifejacket around the torso. Study one (n = 10) quantified the performance of lifejackets immediately following a step into water from height when a lifejacket was worn with a crotch strap (two different tightness) and without a crotch strap. Airway freeboard was improved when wearing a crotch strap (P < 0.05) compared with no crotch strap. Study two used a manikin to examine the performance of lifejackets with and without a crotch strap during 3-h exposures to waves. During exposure to waves, the time taken to aspirate the lethal dose of seawater for drowning was doubled when wearing a crotch strap compared with the no-crotch-strap conditions (P < 0.001). Therefore, wearing a crotch strap (functioning retention system) on a correctly fitted lifejacket improves airway protection following accidental immersion and prolonged wave exposure.

Histological and finite element analysis of cell death due to irreversible electroporation

Irreversible electroporation (IRE) has been shown to be an effective method of killing cells locally. In contrast to radiofrequency ablation, the mechanism by which cells are thought to die via IRE is the creation of pores in cell membranes, without substantial increase in tissue temperature. To determine the degree to which cell death is non-thermal, we evaluated IRE in porcine hepatocytes in vivo. Using pulse widths of 10μs, bursts of 3 kV square-wave pulses were applied through a custom probe to the liver of an anesthetized pig. Affected tissue was evaluated histologically via stainings of hematoxylin & eosin (H&E), nitroblue tetrazolium (NBT) to monitor cell respiration and TUNEL to gauge apoptosis. Temperature was measured during the application of electroporation, and heat transfer was modeled via finite element analysis. Cell death was calculated via Arrhenius kinetics. Four distinct zones were observed within the ring return electrode; heat-fixed tissue, coagulation, necrotic, and viable. The Arrhenius damage integral estimated complete cell death only in the first zone, where the temperature exceeded 70°C, and partial or no cell death in the other zones, where maximum temperature was approximately 45°C. Except for a limited area near the electrode tip, cell death in IRE is predominantly due to a non-thermal mechanism.

CathCam guide wire-directed colonoscopy: first pilot study in patients with a previous incomplete colonoscopy

BACKGROUND AND STUDY AIMS

Conventional colonoscopy as the gold standard for large-bowel diagnostics and therapy may fail in 5 %-20 % of cases, depending on the experience of the examiner. Colonoscopy is regarded as difficult and painful by many patients. In an attempt to overcome the limitations of conventional colonoscopes, a guide wire-directed, thin, flexible diagnostic colonoscope, the CathCam was developed. In this prospective pilot study, we report its use in patients in whom conventional colonoscopy had failed.

PATIENTS AND METHODS

49 patients with a previous or current failure of complete colonoscopy were invited to participate in a trial using the new CathCam system, and 14 (nine men; mean age 59 years) accepted. The CathCam is an 11-mm diameter disposable, multilumen catheter, with visualization by a 3-mm camera with six light-emitting diodes. In the first five patients, the CathCam was inserted over a newly developed 0.024-inch, hinged, lumen-seeking guide wire. Subsequently, a modified combined approach was used: a conventional colonoscope was introduced into the sigmoid or left colon, then the guide wire was advanced as far as possible, followed by CathCam insertion over it. Caecal intubation rate, insertion times and patient discomfort were recorded; patients received low-dose midazolam sedation (2-5 mg).

RESULTS

One patient was excluded during colonoscopy. The caecum could be eventually reached in 12 of 13 patients; in the remaining patient a significant sigmoid stricture could be passed, but further advancement appeared too risky. The mean caecal intubation time was 24 minutes (range 3-105 min). Only two patients experienced pain and discomfort during the procedure (one immediate assessment and one case reported at later telephone interview). No complications occurred, and previously undiagnosed important findings were obtained in 9 cases.

CONCLUSIONS

A combined approach, consisting of guide wire insertion via a partially introduced colonoscope followed by CathCam or colonoscope insertion into the caecum was successful in over 90 % of patients with previous failure of complete colonoscopy. Further improvements may make this system suitable for use as a standard diagnostic colonoscope, either as a single unit (CathCam plus guide wire) or using the guide wire alone with a standard colonoscope in difficult cases.

Right internal carotid pseudoaneurysm mimicking a retropharyngeal abscess in a child

A 7-year-old girl with tonsillar infection with antibiotics. Two weeks later, there was a right sided neck lump. Computed tomography scans demonstrated a predominantly hypodense right retropharyngeal area with peripheral enhancement and mass effect. There was intense enhancement within the postero-superior aspect of the lesion which was continuous with the right internal carotid artery. Ultrasound demonstrated tapering of the right internal carotid artery. Magnetic resonance imaging and magnetic resonance arteriography showed a right internal carotid artery pseudoaneurysm. Surgical exploration confirmed the finding. This case highlights an unusual presentation of an internal carotid pseudoaneurysm and how imaging provided the diagnosis.

Temperature trends in total hip arthroplasty: a retrospective study

The purpose of this study was to define the temporal trend in body temperature of patients during the first 5 days after total hip arthroplasty (THA). The medical records of 98 consecutive THAs were reviewed, 88 clinically uncomplicated cases were included. The average maximum temperature reached during the study period was 38.08 degrees C, a 3.7% (P< or =.01) increase from the preoperative base line of 36.64 degrees C. In this study, 62.5% of patients reached a temperature > or =38.0 degrees C; 19.3% > or = 38.5 degrees C; and 3.4% > or = 39.0 degrees C. No patients had a preoperative temperature of > or =38 degrees C recorded. On the first postoperative day, 39 patients had a temperature > or =38 degrees C. The number of febrile patients progressively decreased until by the fifth postoperative day, only 5 patients had a temperature > or =38 degrees C recorded.

Chloroform: exposure estimation, hazard characterization, and exposure-response analysis

Chloroform has been assessed as a Priority Substance under the Canadian Environmental Protection Act. The general population in Canada is exposed to chloroform principally through inhalation of indoor air, particularly during showering, and through ingestion of tap water. Data on concentrations of chloroform in various media were sufficient to serve as the basis for development of deterministic and probabilistic estimates of exposure for the general population in Canada. On the basis of data acquired principally in studies in experimental animals, chloroform causes hepatic and renal tumors in mice and renal tumors in rats. The weight of evidence indicates that chloroform is likely carcinogenic only at concentrations that induce the obligatory precursor lesions of cytotoxicity and proliferative regenerative response. Since this cytotoxicity is primarily related to rates of formation of reactive, oxidative metabolites, dose response has been characterized in the context of rates of formation of reactive metabolites in the target tissue. Results presented here are from a "hybrid" physiologically based pharmacokinetic (PBPK) animal model that was revised to permit its extension to humans. The relevant measure of exposure response, namely, the mean rate of metabolism in humans associated with a 5% increase in tumor risk (TC05), was estimated on the basis of this PBPK model and compared with tissue dose measures resulting from 24-h multimedia exposure scenarios for Canadians based on midpoint and 95th percentiles for concentrations in outdoor air, indoor air, air in the shower compartment, air in the bathroom after showering, tap water, and food. Nonneoplastic effects observed most consistently at lowest concentrations or doses following repeated exposures of rats and mice to chloroform are cytotoxicity and regenerative proliferation. As for cancer, target organs are the liver and kidney. In addition, chloroform has induced nasal lesions in rats and mice exposed by both inhalation and ingestion at lowest concentrations or doses. The mean rate of metabolism associated with a 5% increase in fatty cysts estimated on the basis of the PBPK model was compared with tissue dose measures resulting from the scenarios already described, and lowest concentrations reported to induce cellular proliferation in the nasal cavities of rats and mice were compared directly with midpoint and 95th percentile estimates of concentrations of chloroform in indoor air in Canada. The degree of confidence in the underlying database and uncertainties in estimates of exposure and in characterization of hazard and dose response are delineated.

Volumetric model determination of the tibia based on 2D radiographs using a 2D/3D database

We present a new concept with mathematical background for the construction of a three-dimensional (3D) volumetric model of the human tibia based on two conventional orthogonal two-dimensional (2D) radiographic images. This approach is supported by a computer database containing a collection of 80 2D/3D image data sets of individual cadaveric tibiae. For each of these tibiae, the database contains digitized 2D orthogonal radiographic images in both anterior and lateral views, and the corresponding 3D CT data obtained by computerized tomography. To obtain a 3D model of a tibia for a given patient, shape matching is performed. The computer finds the most similar tibia to the patient's tibia among the 2D radiographic images in the database by applying a matching process. To improve accuracy, a 2D image warping procedure can be applied on the slices of the selected bone prior to 3D reconstruction. The warping process is controlled by the contour data of the two orthogonal views. We found that the 3D model thus achieved was useful for virtual preoperative planning and for simulation of the internal fixation of long bones.

[The significance of nucleotide repeat sequences in FVIII gene for detecting hemophilia A carriers]

OBJECTIVE

To detect the carriers in hemophilia A(HA) families by haplotype analysis of the microsatellite polymorphisms at intron 13 [13(CA)n] and 22[22(GT)n(AG)n] in the factor VIII (FVIII) gene.

METHOD

Multi-PCR amplification of 13(CA)n and 22(GT)n(AG)n combined with silver staining were used.

RESULTS

In 35 HA families, 11 had HA history. There were 21 female members in the 11 HA families and all of them were subjected to molecular study. Fourteen of the 21 females were confirmed to be carriers and approximately 72.7%(8 of 11) of these families were informative.

CONCLUSIONS

Besides the reliable detection of HA carriers, multi-PCR combined with silver staining in HA analysis has the advantages of time saving, simplicity for performing and no radiation contamination.

Antibacterial agents based on the cyclic D,L-alpha-peptide architecture

The rapid emergence of bacterial infections that are resistant to many drugs underscores the need for new therapeutic agents. Here we report that six- and eight-residue cyclic d,l-alpha-peptides act preferentially on Gram-positive and/or Gram-negative bacterial membranes compared to mammalian cells, increase membrane permeability, collapse transmembrane ion potentials, and cause rapid cell death. The effectiveness of this class of materials as selective antibacterial agents is highlighted by the high efficacy observed against lethal methicillin-resistant Staphylococcus aureus infections in mice. Cyclic d,l-alpha-peptides are proteolytically stable, easy to synthesize, and can be derived from a potentially vast membrane-active sequence space. The unique abiotic structure of the cyclic peptides and their quick bactericidal action may also contribute to limit temporal acquirement of drug resistant bacteria. The low molecular weight d,l-alpha-peptides offer an attractive complement to the current arsenal of naturally derived antibiotics, and hold considerable potential in combating a variety of existing and emerging infectious diseases.

Isolated ventricular septal defect secondary to low-velocity blunt chest trauma

Damage to the ventricular septum resulting from low velocity blunt trauma to the anterior chest wall is a rarely reported disorder. We wish to report a case of an isolated large ventricular septal defect secondary to blunt chest trauma requiring urgent surgical repair in an otherWise healthy 19 year old male. The patient endured a long hospital stay complicated by repeated episodes of pulmonary oedema and ARDS but eventually made a good recovery.

Documentation of in-training assessment for radiology trainees

AIM

To determine if the assessment of radiology trainees can be improved by modifying the in-training assessment form issued by the Royal College of Radiologists (RCR).

MATERIALS AND METHODS

A qualitative study comparing the RCR assessment form with other alternative forms in use in the U.K. Individual semi-structured interviews were conducted with trainees (21) and trainers (18) in Sheffield to collect their views on the RCR form and an alternative form introduced on the North Trent Training Scheme. A postal questionnaire was sent to Heads of Training (24) to find out what assessment forms were in use at other centres and collect their views on the different forms.

RESULTS

Trainees and trainers in Sheffield were virtually unanimous in their support of the new North Trent assessment form. The main advantages perceived were the encouragement of appraisal, setting of objectives and feedback from the trainees. Six other radiology training centres were using alternative assessment forms and all believed their forms had advantages over the RCR in-training assessment form.

CONCLUSION

The results of this study suggest that the assessment process for radiology trainees can be improved by modifications to the RCR in-training assessment form and allows various recommendations to be made.