Genetic control of grain amino acid composition in a UK soft wheat mapping population

Wheat (Triticum aestivum L.) is a major source of nutrients for populations across the globe, but the amino acid composition of wheat grain does not provide optimal nutrition. The nutritional value of wheat grain is limited by low concentrations of lysine (the most limiting essential amino acid) and high concentrations of free asparagine (precursor to the processing contaminant acrylamide). There are currently few available solutions for asparagine reduction and lysine biofortification through breeding. In this study, we investigated the genetic architecture controlling grain free amino acid composition and its relationship to other traits in a Robigus × Claire doubled haploid population. Multivariate analysis of amino acids and other traits showed that the two groups are largely independent of one another, with the largest effect on amino acids being from the environment. Linkage analysis of the population allowed identification of quantitative trait loci (QTL) controlling free amino acids and other traits, and this was compared against genomic prediction methods. Following identification of a QTL controlling free lysine content, wheat pangenome resources facilitated analysis of candidate genes in this region of the genome. These findings can be used to select appropriate strategies for lysine biofortification and free asparagine reduction in wheat breeding programs.

Reducing Dietary Acrylamide Exposure from Wheat Products through Crop Management and Imaging

The nutritional safety of wheat-based food products is compromised by the presence of the processing contaminant acrylamide. Reduction of the key acrylamide precursor, free (soluble, non-protein) asparagine, in wheat grain can be achieved through crop management strategies, but such strategies have not been fully developed. We ran two field trials with 12 soft (biscuit) wheat varieties and different nitrogen, sulfur, potassium, and phosphorus fertilizer combinations. Our results indicated that a nitrogen-to-sulfur ratio of 10:1 kg/ha was sufficient to prevent large increases in free asparagine, whereas withholding potassium or phosphorus alone did not cause increases in free asparagine when sulfur was applied. Multispectral measurements of plants in the field were able to predict the free asparagine content of grain with an accuracy of 71%, while a combination of multispectral, fluorescence, and morphological measurements of seeds could distinguish high free asparagine grain from low free asparagine grain with an accuracy of 86%. The acrylamide content of biscuits correlated strongly with free asparagine content and with color measurements, indicating that agronomic strategies to decrease free asparagine would be effective and that quality control checks based on product color could eliminate high acrylamide biscuit products.

Sequential action of antibacterial effectors in Dictyostelium discoideum phagosomes

Mammalian professional phagocytic cells ingest and kill invading microorganisms and prevent the development of bacterial infections. Our understanding of the sequence of events that results in bacterial killing and permeabilization in phagosomes is still largely incomplete. In this study, we used the Dictyostelium discoideum amoeba as a model phagocyte to study the fate of the bacteria Klebsiella pneumoniae inside phagosomes. Our analysis distinguishes three consecutive phases: bacteria first lose their ability to divide (killing), then their cytosolic content is altered (permeabilization), and finally their DNA is degraded (digestion). Phagosomal acidification and production of free radicals are necessary for rapid killing, membrane-permeabilizing proteins BpiC and AlyL are required for efficient permeabilization. These results illustrate how a combination of genetic and microscopical tools can be used to finely dissect the molecular events leading to bacterial killing and permeabilization in a maturing phagosome.

668 Introduction of a Pre-Operative Assessment Clinic for Elective Procedures in a Renal Replacement Therapy Unit - Analysis of Effect on Cancellation of Procedures

Aim

In September 2020, our Renal and Transplant unit introduced a new formalised protocol for Pre-Operative Assessment Clinics (POACs), led by SHO-grade junior doctors. This study aims to investigate the efficacy of the new protocol.

Method

All elective operations including dialysis access procedures, transplant urology, parathyroidectomies and hernia repairs conducted by a single renal replacement therapy unit were examined over an 18-month period prior to POAC implementation, then a 12-month period following implementation. Living donor transplants and nephrectomies were excluded.

On-the day (OTD) cancellation causes were analysed and categorised into:

Results

Total cases performed:

Pre-implementation = 921, post-implementation = 415.

OTD cancellations:

Pre-implementation - total of 211/921 (22.9%). 90 (9.8%) were due to predictable patient factors, 54 (5.9%) for unpredictable patient factors and 67 (7.2%) for hospital factors.

Post-implementation - total of 58/415 (11.6%). 32 (7.7%) for unpredictable patient factors and 12 (2.9%) for hospital factors. Four (1%) were cancelled for predictable patient factors, two due to patients presenting with hypertension.

Conclusions

Patients with renal failure have multiple co-morbidities. Optimising pre-operative care is crucial to ensure they receive timely treatment. This audit has demonstrated that a redesigned POAC led to a reduction of OTD cancellation rates from 22.9% to 11.6%, with a marked reduction in predictable causes for cancellations. Further improvements and re-audit are planned.

Understanding the Relationships between Free Asparagine in Grain and Other Traits to Breed Low-Asparagine Wheat

Since the discovery of acrylamide in food, and the identification of free asparagine as the key determinant of acrylamide concentration in wheat products, our understanding of how grain asparagine content is regulated has improved greatly. However, the targeted reduction in grain asparagine content has not been widely implemented in breeding programmes so far. Here we summarise how free asparagine concentration relates to other quality and agronomic traits and show that these relationships are unlikely to pose major issues for the breeding of low-asparagine wheat. We also outline the strategies that are possible for the breeding of low-asparagine wheat, using both natural and induced variation.

Reduced free asparagine in wheat grain resulting from a natural deletion of TaASN-B2: investigating and exploiting diversity in the asparagine synthetase gene family to improve wheat quality

BACKGROUND

Understanding the determinants of free asparagine concentration in wheat grain is necessary to reduce levels of the processing contaminant acrylamide in baked and toasted wheat products. Although crop management strategies can help reduce asparagine concentrations, breeders have limited options to select for genetic variation underlying this trait. Asparagine synthetase enzymes catalyse a critical step in asparagine biosynthesis in plants and, in wheat, are encoded by five homeologous gene triads that exhibit distinct expression profiles. Within this family, TaASN2 genes are highly expressed during grain development but TaASN-B2 is absent in some varieties.

RESULTS

Natural genetic diversity in the asparagine synthetase gene family was assessed in different wheat varieties revealing instances of presence/absence variation and other polymorphisms, including some predicted to affect the function of the encoded protein. The presence and absence of TaASN-B2 was determined across a range of UK and global common wheat varieties and related species, showing that the deletion encompassing this gene was already present in some wild emmer wheat genotypes. Expression profiling confirmed that TaASN2 transcripts were only detectable in the grain, while TaASN3.1 genes were highly expressed during the early stages of grain development. TaASN-A2 was the most highly expressed TaASN2 homeologue in most assayed wheat varieties. TaASN-B2 and TaASN-D2 were expressed at similar, lower levels in varieties possessing TaASN-B2. Expression of TaASN-A2 and TaASN-D2 did not increase to compensate for the absence of TaASN-B2, so total TaASN2 expression was lower in varieties lacking TaASN-B2. Consequently, free asparagine concentrations in field-produced grain were, on average, lower in varieties lacking TaASN-B2, although the effect was lost when free asparagine accumulated to very high concentrations as a result of sulphur deficiency.

CONCLUSIONS

Selecting wheat genotypes lacking the TaASN-B2 gene may be a simple and rapid way for breeders to reduce free asparagine concentrations in commercial wheat grain.

Seed Banks as Incidental Fungi Banks: Fungal Endophyte Diversity in Stored Seeds of Banana Wild Relatives

Seed banks were first established to conserve crop genetic diversity, but seed banking has more recently been extended to wild plants, particularly crop wild relatives (CWRs) (e.g., by the Millennium Seed Bank (MSB), Royal Botanic Gardens Kew). CWRs have been recognised as potential reservoirs of beneficial traits for our domesticated crops, and with mounting evidence of the importance of the microbiome to organismal health, it follows that the microbial communities of wild relatives could also be a valuable resource for crop resilience to environmental and pathogenic threats. Endophytic fungi reside asymptomatically inside all plant tissues and have been found to confer advantages to their plant host. Preserving the natural microbial diversity of plants could therefore represent an important secondary conservation role of seed banks. At the same time, species that are reported as endophytes may also be latent pathogens. We explored the potential of the MSB as an incidental fungal endophyte bank by assessing diversity of fungi inside stored seeds. Using banana CWRs in the genus Musa as a case-study, we sequenced an extended ITS-LSU fragment in order to delimit operational taxonomic units (OTUs) and used a similarity and phylogenetics approach for classification. Fungi were successfully detected inside just under one third of the seeds, with a few genera accounting for most of the OTUs-primarily Lasiodiplodia, Fusarium, and Aspergillus-while a large variety of rare OTUs from across the Ascomycota were isolated only once. Fusarium species were notably abundant-of significance in light of Fusarium wilt, a disease threatening global banana crops-and so were targeted for additional sequencing with the marker EF1α in order to delimit species and place them in a phylogeny of the genus. Endophyte community composition, diversity and abundance was significantly different across habitats, and we explored the relationship between community differences and seed germination/viability. Our results show that there is a previously neglected invisible fungal dimension to seed banking that could well have implications for the seed collection and storage procedures, and that collections such as the MSB are indeed a novel source of potentially useful fungal strains.

The Sulphur Response in Wheat Grain and Its Implications for Acrylamide Formation and Food Safety

Free (soluble, non-protein) asparagine concentration can increase many-fold in wheat grain in response to sulphur deficiency. This exacerbates a major food safety and regulatory compliance problem for the food industry because free asparagine may be converted to the carcinogenic contaminant, acrylamide, during baking and processing. Here, we describe the predominant route for the conversion of asparagine to acrylamide in the Maillard reaction. The effect of sulphur deficiency and its interaction with nitrogen availability is reviewed, and we reiterate our advice that sulphur should be applied to wheat being grown for human consumption at a rate of 20 kg per hectare. We describe the genetic control of free asparagine accumulation, including genes that encode metabolic enzymes (asparagine synthetase, glutamine synthetase, glutamate synthetase, and asparaginase), regulatory protein kinases (sucrose nonfermenting-1 (SNF1)-related protein kinase-1 (SnRK1) and general control nonderepressible-2 (GCN2)), and basic leucine zipper (bZIP) transcription factors, and how this genetic control responds to sulphur, highlighting the importance of asparagine synthetase-2 (ASN2) expression in the embryo. We show that expression of glutamate-cysteine ligase is reduced in response to sulphur deficiency, probably compromising glutathione synthesis. Finally, we describe unexpected effects of sulphur deficiency on carbon metabolism in the endosperm, with large increases in expression of sucrose synthase-2 (SuSy2) and starch synthases.

Depressive disorders and unprotected casual anal sex among Australian homosexually active men in primary care

OBJECTIVE

To examine the relationship between depressive disorders and unprotected anal intercourse with casual partners, among homosexually active men attending for primary care.

METHODS

The first 460 homosexually active men enrolling in an Australian integrated primary care programme were screened for current depressive disorders using the Primary Care Evaluation of Mental Disorders (PRIME-MD) and completed questionnaires on their sexual behaviour in the prior 6 months. One hundred and sixty-two (35%) were HIV positive, 283 (62%) were HIV negative and 15 (3%) were untested.

RESULTS

The prevalence of major depressive episode (MDE), as measured by the PRIME-MD, on enrollment was 28% (129/460), while the prevalence of dysthymic disorder (DD) was 26% (121/460). These include 84 men (18%) who met the criteria for both disorders ('double depression'). Neither disorder was associated with HIV status. Men with MDE were less likely to have been sexually active than the remainder of the cohort (90/129 [70%] vs. 291/331 [88%]; OR: 0.32 [95% CI: 0.19-0.52]; P<0.0001). Men with DD alone, however, were significantly more likely than men with neither disorder to report having had unprotected anal intercourse with a casual partner (11/38 [29%] vs. 43/292 [15%]; OR: 2.36 [95%CI: 1.09-5.10]; P=0.035).

CONCLUSIONS

Depressive disorders were highly prevalent in this cohort and independent of HIV status. MDE was associated with reduced sexual activity. Among men without MDE, the presence of DD was independently associated with an increased likelihood of reporting unsafe anal sex with a casual partner in the prior 6 months.

Lewis-Base Adducts of Group I Metal(I) Compounds. XXVI. Solid-State Cross-Polarization Magic-Angle-Spinning 31P N.M.R. and Structural Studies on 1:1 Adducts of Triphenylphosphine With Gold(I) Salts

Linear, two-coordinate compounds of molecular formula (PPh3) AuX have been characterized by solid-state and solution 31P n.m.r. spectroscopy, and single-crystal X-ray diffraction techniques. The solid state n.m.r. spectra reveal single, broad resonance lines for X = NO3 (chemical shift 19 ppm , ref. 85% H3PO4), CH3C02 (24 ppm), SCN (36ppm), CN (37 ppm ) and CH3 (47 ppm ) and doublets for X = Cl (27, 33 ppm ), Br (28, 36 ppm ) and I (34, 38 ppm ), the latter three spectra being recorded at 121.47 MHz and 161.96 MHz. Solution spectra show relatively sharp single resonances for each compound with 6 values generally slightly higher than in the solid state. Crystal data are reported for X = NO3, space gro )p P21/c, a 8 895(9), b 10.117(8), c 19.57(2) �; β 97.43(8)�, Au-P,O = 2.199(5), 2.02(1) �. Crystals of compounds with X = Br, I and SCN are isomorphous with the AuCl compound, belonging to space group 212121. For X = Br, a 12.479(5), b 13.45(1), c 10.0!2(8) �; Au-P, Br = 2.252(6), 2.407(2) �. For X = I, a 12.529(8), b 13.870(5), c 10.188(4) �; Au-P, I = 2.254(5), 2.556(2) �. For X = SCN, a 12.257(5), b 13.776(8), c 10.754(6) �; Au-P, S = 2.252(7), 2.304(7) �.