RNA-binding properties orchestrate TDP-43 homeostasis through condensate formation in vivo.

Insoluble cytoplasmic aggregate formation of the RNA-binding protein TDP-43 is a major hallmark of neurodegenerative diseases including Amyotrophic Lateral Sclerosis. TDP-43 localizes predominantly in the nucleus, arranging itself into dynamic condensates through liquid-liquid phase separation (LLPS). Mutations and post-translational modifications can alter the condensation properties of TDP-43, contributing to the transition of liquid-like biomolecular condensates into solid-like aggregates. However, to date it has been a challenge to study the dynamics of this process in vivo. We demonstrate through live imaging that human TDP-43 undergoes nuclear condensation in spinal motor neurons in a living animal. RNA-binding deficiencies as well as post-translational modifications can lead to aberrant condensation and altered TDP-43 compartmentalization. Single-molecule tracking revealed an altered mobility profile for RNA-binding deficient TDP-43. Overall, these results provide a critically needed in vivo characterization of TDP-43 condensation, demonstrate phase separation as an important regulatory mechanism of TDP-43 accessibility, and identify a molecular mechanism of how functional TDP-43 can be regulated.

Dynamic relationships among feeling fat, fear of weight gain, and eating disorder symptoms in an eating disorder sample.

Feeling fat and fear of weight gain are key cognitive-affective symptoms that are theorized to maintain eating disorders (EDs). Little research has examined the dynamic relationships among feeling fat, fear of weight gain, emotions, cognitions, and ED behaviors. Furthermore, it is unknown if these relations vary by ED diagnosis (e.g., anorexia nervosa (AN) vs other ED). The current study (N = 94 ED participants; AN n = 64) utilized ecological momentary assessments collected four times a day for 18 days (72 timepoints) asking about feeling fat, fear of weight gain, emotions (i.e., anxiety, guilt), cognitions (i.e., feelings of having overeaten, thoughts about dieting), and ED behaviors (i.e., vomiting, diuretic/laxative use, excessive exercise, body checking, self-weighing, binge-eating, restriction) at stressful timepoints (contemporaneous [mealtime], and prospective/temporal [next-meal]). Multilevel modeling was used to test for between and within-person associations. Higher feeling fat and fear of weight gain independently predicted higher next-meal emotions (i.e., anxiety, guilt), cognitions (i.e., feelings of having overeaten, thoughts about dieting, fear of weight gain, feeling fat), and ED behaviors (i.e., body checking, self-weighing [feeling fat]). There were relationships in the opposite direction, such that some emotions, cognitions, and ED behaviors prospectively predicted feeling fat and fear of weight gain, suggesting existence of a reciprocal cycle. Some differences were found via diagnosis. Findings pinpoint specific dynamic and cyclical relationships among feeling fat, fear of weight gain, and specific ED symptoms, and suggest the need for more research on how feeling fat, fear of weight gain and cognitive-affective-behavioral aspects of ED operate. Future research can test if treatment interventions targeted at feeling fat and fear of weight gain may disrupt these cycles.

Identification of phosphorylated tau protein interactors in progressive supranuclear palsy (PSP) reveals networks involved in protein degradation, stress response, cytoskeletal dynamics, metabolic processes, and neurotransmission.

Progressive supranuclear palsy (PSP) is a late-onset neurodegenerative disease defined pathologically by the presence of insoluble phosphorylated-Tau (p-Tau) in neurons and glia. Identifying co-aggregating proteins within p-Tau inclusions may reveal important insights into processes affected by the aggregation of Tau. We used a proteomic approach, which combines antibody-mediated biotinylation and mass spectrometry (MS) to identify proteins proximal to p-Tau in PSP. Using this proof-of-concept workflow for identifying interacting proteins of interest, we characterized proteins proximal to p-Tau in PSP cases, identifying >84% of previously identified interaction partners of Tau and known modifiers of Tau aggregation, while 19 novel proteins not previously found associated with Tau were identified. Furthermore, our data also identified confidently assigned phosphorylation sites that have been previously reported on p-Tau. Additionally, using ingenuity pathway analysis (IPA) and human RNA-seq datasets, we identified proteins previously associated with neurological disorders and pathways involved in protein degradation, stress responses, cytoskeletal dynamics, metabolism, and neurotransmission. Together, our study demonstrates the utility of biotinylation by antibody recognition (BAR) approach to answer a fundamental question to rapidly identify proteins in proximity to p-Tau from post-mortem tissue. The application of this workflow opens up the opportunity to identify novel protein targets to give us insight into the biological process at the onset and progression of tauopathies.

Female reproductive fluids 'rescue' sperm from phenotypic ageing in an external fertilizer.

Female reproductive fluids (FRFs) serve key reproductive functions in sexually reproducing animals, including modifying the way sperm swim and detect eggs, and influencing sperm lifespan. Despite the central role of FRF during fertilization, we know surprisingly little about sperm-FRF interactions under different environmental conditions. Theory suggests that in external fertilizers FRF may 'rescue' sperm from ageing effects as they search to fertilize eggs. Here, we test the interaction between these two fundamental properties of the fertilization environment, ejaculate age (i.e. time since ejaculation) and FRF, on a range of functional sperm phenotypes in a broadcast spawning mussel, Mytilus galloprovincialis. We found that the effects of ejaculate age on multivariate sperm motility traits and total sperm motility were altered by FRF, and that longer-lived sperm exhibit stronger, likely more advantageous, responses to FRF after periods of ageing. We also detected significant among-male variation in the relationship between sperm motility traits and ejaculate age; notably, these patterns were only revealed when sperm encountered FRF. Collectively these findings underscore the importance of considering female reproductive physiology when interpreting ageing-related declines in sperm motility, as doing so may expose importance sources of variation in sperm phenotypic plasticity among males and environments.

Complex polyploid and hybrid species in an apomictic and sexual tropical forage grass group: genomic composition and evolution in Urochloa (Brachiaria) species.

BACKGROUND AND AIMS: Diploid and polyploid Urochloa (including Brachiaria, Panicum and Megathyrsus species) C4 tropical forage grasses originating from Africa are important for food security and the environment, often being planted in marginal lands worldwide. We aimed to characterize the nature of their genomes, the repetitive DNA and the genome composition of polyploids, leading to a model of the evolutionary pathways within the group including many apomictic species. METHODS: Some 362 forage grass accessions from international germplasm collections were studied, and ploidy was determined using an optimized flow cytometry method. Whole-genome survey sequencing and molecular cytogenetic analysis were used to identify chromosomes and genomes in Urochloa accessions belonging to the 'brizantha' and 'humidicola' agamic complexes and U. maxima. KEY RESULTS: Genome structures are complex and variable, with multiple ploidies and genome compositions within the species, and no clear geographical patterns. Sequence analysis of nine diploid and polyploid accessions enabled identification of abundant genome-specific repetitive DNA motifs. In situ hybridization with a combination of repetitive DNA and genomic DNA probes identified evolutionary divergence and allowed us to discriminate the different genomes present in polyploids. CONCLUSIONS: We suggest a new coherent nomenclature for the genomes present. We develop a model of evolution at the whole-genome level in diploid and polyploid accessions showing processes of grass evolution. We support the retention of narrow species concepts for Urochloa brizantha, U. decumbens and U. ruziziensis, and do not consider diploids and polyploids of single species as cytotypes. The results and model will be valuable in making rational choices of parents for new hybrids, assist in use of the germplasm for breeding and selection of Urochloa with improved sustainability and agronomic potential, and assist in measuring and conserving biodiversity in grasslands.

Paternal environment effects are driven by female reproductive fluid but not sperm age in an external fertilizer.

Sperm ageing after ejaculation can generate paternal environment effects that impact offspring fitness. In many species, female reproductive fluids (FRFs), i.e. ancillary fluids released by eggs or within the female reproductive tract, may protect sperm from ageing and can additionally interact with sperm to influence offspring viability. This raises the intriguing prospect that FRFs may alleviate paternal effects associated with sperm ageing. Here, we test this novel hypothesis using the broadcast spawning mussel, Mytilus galloprovincialis. We show that incubating sperm in FRF prior to fertilization increases offspring viability, and that these effects occur independently of sperm age. Our results provide novel evidence that FRFs allow females to selectively bias fertilization toward higher quality sperm within an ejaculate, which in turn yields more viable offspring. We consider this FRF-mediated paternal effect in the context of female physiological control over fertilization and the transgenerational effects of female-regulated haploid selection.

Weight status is associated with clinical characteristics among individuals with bulimia nervosa.

Recent studies have found increasing rates of overweight and obesity in bulimia nervosa (BN). However, the relationships between body mass index (BMI) and BN symptoms and other clinically relevant constructs are unknown. Participants (N = 152 adults with BN) were assigned to three groups by BMI: group with no overweight or obesity (NOW-BN; BMI <25; N = 32), group with overweight (OW-BN; BMI ≥25 and <30; N = 66), and group with obesity (O-BN; BMI ≥30; N = 54). We compared the groups on demographics, diet and weight histories, body esteem, BN symptoms, and depression using chi square, analysis of variance, analysis of covariance, and Poisson regression models. The O-BN group was older (d = 0.57) and OW-BN and O-BN groups had greater proportions of race/ethnic minorities than NOW-BN group. The O-BN group was significantly younger at first diet (d = 0.41) and demonstrated significantly higher cognitive dietary restraint (d = 0.31). Compared to NOW-BN, O-BN participants had lower incidence of objective binge eating (incidence rate ratio [IRR] = 4.86) and driven exercise (IRR = 7.13), and greater incidence of vomiting (IRR = 9.30), laxative misuse (IRR = 4.01), and diuretic misuse (d = 2.08). O-BN participants also experienced higher shape (d = 0.41) and weight (d = 0.42) concerns than NOW-BN and OW-BN, although NOW-BN experienced higher shape (d = 0.44) and weight (d = 0.39) concerns than OW-BN. Groups did not differ on depression scores. These results were replicated when examining BMI as a continuous predictor across the full sample, with the exception of objective binge eating and driven exercise, which were not significantly associated with BMI. Individuals with BN and comorbid obesity have distinct clinical characteristics. Existing interventions may need to be adapted to meet clinical needs of these individuals.

Suppression of a BAHD acyltransferase decreases p-coumaroyl on arabinoxylan and improves biomass digestibility in the model grass Setaria viridis.

Grass cell walls have hydroxycinnamic acids attached to arabinosyl residues of arabinoxylan (AX), and certain BAHD acyltransferases are involved in their addition. In this study, we characterized one of these BAHD genes in the cell wall of the model grass Setaria viridis. RNAi silenced lines of S. viridis (SvBAHD05) presented a decrease of up to 42% of ester-linked p-coumarate (pCA) and 50% of pCA-arabinofuranosyl, across three generations. Biomass from SvBAHD05 silenced plants exhibited up to 32% increase in biomass saccharification after acid pre-treatment, with no change in total lignin. Molecular dynamics simulations suggested that SvBAHD05 is a p-coumaroyl coenzyme A transferase (PAT) mainly involved in the addition of pCA to the arabinofuranosyl residues of AX in Setaria. Thus, our results provide evidence of p-coumaroylation of AX promoted by SvBAHD05 acyltransferase in the cell wall of the model grass S. viridis. Furthermore, SvBAHD05 is a promising biotechnological target to engineer crops for improved biomass digestibility for biofuels, biorefineries and animal feeding.

Narrow and Stable Single Photon Emission from Dibenzoterrylene in para-Terphenyl Nanocrystals.

Single organic molecules are promising photon sources for quantum technologies. In this work we show photon emission from dibenzoterrylene, a widely used organic emitter, in a new host matrix, para-terphenyl. We present a reprecipitation growth method that produces para-terphenyl nanocrystals which are ideal for integration into nanophotonic devices due to their small size. We characterise the optical properties of dibenzoterrylene in nanocrystals at room and cryogenic temperatures, showing bright, narrow emission from a single molecule. Spectral data on the vibrational energies is presented and a further 25 additional molecules are characterised. This emitter-host combination has potential for quantum technology purposes with wavelengths suitable for interfacing with quantum memories.

Ocean acidification alters sperm responses to egg-derived chemicals in a broadcast spawning mussel.

The continued emissions of anthropogenic carbon dioxide are causing progressive ocean acidification (OA). While deleterious effects of OA on biological systems are well documented in the growth of calcifying organisms, lesser studied impacts of OA include potential effects on gamete interactions that determine fertilization, which are likely to influence the many marine species that spawn gametes externally. Here, we explore the effects of OA on the signalling mechanisms that enable sperm to track egg-derived chemicals (sperm chemotaxis). We focus on the mussel Mytilus galloprovincialis, where sperm chemotaxis enables eggs to bias fertilization in favour of genetically compatible males. Using an experimental design based on the North Carolina II factorial breeding design, we test whether the experimental manipulation of seawater pH (comparing ambient conditions to predicted end-of-century scenarios) alters patterns of differential sperm chemotaxis. While we find no evidence that male-female gametic compatibility is impacted by OA, we do find that individual males exhibit consistent variation in how their sperm perform in lowered pH levels. This finding of individual variability in the capacity of ejaculates to respond to chemoattractants under acidified conditions suggests that climate change will exert considerable pressure on male genotypes that can withstand an increasingly hostile fertilization environment.

Reporting racial and ethnic diversity in eating disorder research over the past 20 years.

OBJECTIVE: Recent public awareness of racial and ethnic disparities has again brought to light issues of diversity, equity, and inclusion in the eating disorders field. However, empirical information on racial and ethnic representation in eating disorders research is limited, making it difficult to understand where improvements are needed. METHOD: This study reviewed all studies including human participants published in the International Journal of Eating Disorders in 2000, 2010, and 2020. Differences in likelihood of reporting race and ethnicity were calculated based on study year, location, and diagnostic categories. RESULTS: Out of 377 manuscripts, 45.2% reported information on the race and ethnicity of study participants. Studies conducted in the United States were more likely to report (128/173), and those conducted in Europe were less likely to report (5/61) on race and ethnicity than those conducted outside of those regions. Rates of reporting increased from 2000 to 2020. White participants made up approximately 70% of the samples that reported race and ethnicity data. Hispanic participants made up approximately 10% of samples reporting race and ethnicity. Participants from all other races and ethnicities made up less than 5% each. DISCUSSION: Although rates of reporting race and ethnicity increased over time, most participants were White. Rates of reporting also differed by the geographical region, which may reflect variability in how information on race and ethnicity is collected across countries. More attention toward capturing the cultural background of research participants and more inclusivity in research are needed in the eating disorders field.

Eating expectancies and hedonic hunger among individuals with bulimia-spectrum eating disorders who plan binge-eating episodes.

OBJECTIVE: Binge planning (BP; i.e., preparatory thoughts and actions to facilitate future binge-eating episodes) is hypothesized to distract individuals from negative affect and increase the salience of food. Thus, individuals who engage in BP may report greater positive eating expectancies (i.e., beliefs about the outcomes of eating) and hedonic hunger (i.e., desire to eat for pleasure), as BP may increase the likelihood of obtaining these expected outcomes; but empirical tests of this possibility are needed. METHOD: Prior to starting treatment, adults (N = 86) with bulimia-spectrum eating disorders were assessed for engagement in BP and self-reported on eating expectancies and hedonic hunger. RESULTS: Twenty-nine participants (33.7%) reported planning at least one binge-eating episode in the previous 28 days. Compared to individuals who did not report BP, individuals who reported BP had greater expectancies that eating would alleviate negative affect (t = -2.54, p = .013) and boredom (U = 503.50, p = .006). Groups did not differ on levels of hedonic hunger (t = -1.68, p = .096). DISCUSSION: These findings suggest that BP status is linked to expectancies that eating will reduce negative affect. However, more data are needed to determine the temporal relationships among eating expectancies, hedonic hunger and BP. TRIAL REGISTRATION NUMBERS: NCT02716831, NCT03673540.

A network investigation of core symptoms and pathways across duration of illness using a comprehensive cognitive-behavioral model of eating-disorder symptoms.

BACKGROUND: In the past decade, network analysis (NA) has been applied to psychopathology to quantify complex symptom relationships. This statistical technique has demonstrated much promise, as it provides researchers the ability to identify relationships across many symptoms in one model and can identify central symptoms that may predict important clinical outcomes. However, network models are highly influenced by node selection, which could limit the generalizability of findings. The current study (N = 6850) tests a comprehensive, cognitive-behavioral model of eating-disorder symptoms using items from two, widely used measures (Eating Disorder Examination Questionnaire and Eating Pathology Symptoms Inventory). METHODS: We used NA to identify central symptoms and compared networks across the duration of illness (DOI), as chronicity is one of the only known predictors of poor outcome in eating disorders (EDs). RESULTS: Our results suggest that eating when not hungry and feeling fat were the most central symptoms across groups. There were no significant differences in network structure across DOI, meaning the connections between symptoms remained relatively consistent. However, differences emerged in central symptoms, such that cognitive symptoms related to overvaluation of weight/shape were central in individuals with shorter DOI, and behavioral central symptoms emerged more in medium and long DOI. CONCLUSIONS: Our results have important implications for the treatment of individuals with enduring EDs, as they may have a different core, maintaining symptoms. Additionally, our findings highlight the importance of using comprehensive, theoretically- or empirically-derived models for NA.

Allele mining in diverse accessions of tropical grasses to improve forage quality and reduce environmental impact.

BACKGROUND AND AIMS: The C4Urochloa species (syn. Brachiaria) and Megathyrsus maximus (syn. Panicum maximum) are used as pasture for cattle across vast areas in tropical agriculture systems in Africa and South America. A key target for variety improvement is forage quality: enhanced digestibility could decrease the amount of land required per unit production, and enhanced lipid content could decrease methane emissions from cattle. For these traits, loss-of-function (LOF) alleles in known gene targets are predicted to improve them, making a reverse genetics approach of allele mining feasible. We therefore set out to look for such alleles in diverse accessions of Urochloa species and Megathyrsus maximus from the genebank collection held at the CIAT. METHODS: We studied allelic diversity of 20 target genes (11 for digestibility, nine for lipid content) in 104 accessions selected to represent genetic diversity and ploidy levels of U. brizantha, U. decumbens, U. humidicola, U. ruziziensis and M. maximum. We used RNA sequencing and then bait capture DNA sequencing to improve gene models in a U. ruziziensis reference genome to assign polymorphisms with high confidence. KEY RESULTS: We found 953 non-synonymous polymorphisms across all genes and accessions; within these, we identified seven putative LOF alleles with high confidence, including those in the non-redundant SDP1 and BAHD01 genes present in diploid and tetraploid accessions. These LOF alleles could respectively confer increased lipid content and digestibility if incorporated into a breeding programme. CONCLUSIONS: We demonstrated a novel, effective approach to allele discovery in diverse accessions using a draft reference genome from a single species. We used this to find gene variants in a collection of tropical grasses that could help reduce the environmental impact of cattle production.

The thermal environment of sperm affects offspring success: a test of the anticipatory paternal effects hypothesis in the blue mussel.

There has been an explosion of recent evidence that environments experienced by fathers or their ejaculates can influence offspring phenotypes (paternal effects). However, little is known about whether such effects are adaptive, which would have far-reaching implications for the many species facing rapidly changing environments. For example, some arguments suggest paternal effects might be a source of cross-generational plasticity, preparing offspring to face similar conditions to their father (anticipatory hypothesis). Alternatively, ejaculate-mediated effects on offspring may be non-adaptive by-products of stress. Here, we conduct an experiment to distinguish between these predictions, exposing ejaculates of the externally fertilizing mussel Mytilus galloprovincialis to ambient (19°C) and high (24°C) temperatures, then rearing offspring groups in temperatures that match and mismatch those of sperm. We find that, overall, high temperature-treated sperm induced higher rates of normal offspring development and higher success in transitioning to second-stage larvae, which may represent adaptive epigenetic changes or selection on sperm haplotypes. However, the progeny of high temperature-treated sperm did not perform better than those of ambient temperature-treated sperm when rearing temperatures were high. Overall, these findings offer little support for the anticipatory hypothesis and suggest instead that beneficial paternal effects may be eroded when offspring develop under stressful conditions.

Network investigation of eating disorder symptoms and positive and negative affect in a clinical eating disorder sample.

OBJECTIVE: Growing literature suggests that emotions influence the maintenance of eating disorder (ED) symptoms. However, most research has studied the relationship between ED symptoms and affect broadly (i.e., negative affect [NA], positive affect [PA]), rather than examining models comprised of multiple specific affective states (e.g., upset, proud). METHOD: The current study (N = 196 individuals with EDs) used network analysis to examine the most interconnected (i.e., central) NA and PA states in EDs and test the complex associations between specific NA, PA, and ED symptoms. We estimated two networks: one with affective states only and another with affective states and ED symptoms. RESULTS: Feeling distressed, afraid, attentive, and determined were the most central symptoms in the affect-only network. ED symptoms related to overvaluation of weight and shape, including affect-based ED symptoms (i.e., guilt about eating), were central in the network of affect and ED symptoms. Guilt about eating and shame were central bridge symptoms across affect and ED symptom clusters, meaning that they were each strongly connected across clusters, and may represent important pathways among affect and ED symptoms. DISCUSSION: Limitations include the cross-sectional and between-person nature of these analyses, from which we cannot derive causal or within-persons processes. Clinical interventions that target central and bridge symptoms (e.g., fear, shame) may disrupt the reinforcing cycle of NA in EDs that may contribute to ED behaviors. Future research should examine relationships among affective states and ED symptoms in longitudinal and intraindividual network models to develop more effective treatments for EDs.

Comprehensive Cognitive-Behavioral Interventions Augment Diaphragmatic Breathing for Rumination Syndrome: A Proof-of-Concept Trial.

BACKGROUND: Rumination syndrome (RS) is often treated in medical settings with 1-2 sessions of diaphragmatic breathing to target reflexive abdominal wall contraction in response to conditioned cues (e.g., food). However, many patients remain symptomatic and require additional behavioral interventions. AIMS: In an attempt to augment diaphragmatic breathing with additional interventions, we tested the proof-of-concept of a comprehensive Cognitive-Behavioral Therapy (CBT) for RS. METHODS: In an uncontrolled trial, adults with RS completed a 5-8 session CBT protocol, delivered by one of two psychology behavioral health providers. CBT included two main phases: awareness training and diaphragmatic breathing (Phase 1) and modularized interventions chosen by the therapist and patient to target secondary maintenance mechanisms (Phase 2). At pre-treatment, post-treatment, and 3-month follow-up, participants completed a semi-structured interview on RS symptoms with an independent evaluator. RESULTS: Of 10 eligible individuals (ages 20-67 years, 50% female) offered treatment, all 10 initiated treatment and eight completed it. All participants endorsed high treatment credibility at Session 1. Permutation-based repeated measures ANOVA showed participants achieved large reductions in regurgitations across treatment [F(1,7) = 17.7, p = .007, η p2 = .69]. Although participants reduced regurgitations with diaphragmatic breathing during Phase 1, addition of other CBT strategies in Phase 2 produced further large reductions [F(1,7) = 6.3, p = .04, η p2 = .47]. Of eight treatment completers, treatment gains were maintained at 3-month follow-up for n = 6. CONCLUSIONS: Findings provide evidence of feasibility, acceptability, and proof-of-concept for a comprehensive CBT for RS that includes interventions in addition to diaphragmatic breathing to target secondary maintenance mechanisms. Randomized controlled trials are needed.

Enhancing Integrative Cognitive-Affective Therapy with ecological momentary interventions: A pilot trial.

OBJECTIVE: Although current treatments are effective for some patients with eating disorders, a large number of patients remain partially or fully symptomatic post-treatment. This may be related to poor utilization of treatment skills outside of the therapy office. Smartphone applications that can detect and intervene during moments of need could facilitate such skill use between sessions. METHOD: Individuals (N = 16) participated in a small pilot open trial where they received 21 sessions of in-person Integrative Cognitive-Affective Therapy (ICAT) therapy an app (iCAT+) that delivers ecological momentary interventions (EMI) in response to user-entered data. Data were collected on the feasibility and acceptability of this treatment approach and on preliminary indicators of treatment outcomes. RESULTS: Participants found iCAT+ as a treatment augmentation acceptable and indicated it had clinical utility as an adjunct to in-person therapy, although analyses indicated poor compliance with data entry needed to trigger EMI delivery. This suggests that long-term use of EMI requiring ongoing data entry is infeasible. CONCLUSIONS: We describe lessons learned from our initial pilot trial and future directions for the development of impactful EMI systems that can be used to augment in-person therapies.

High post-anthesis temperature effects on bread wheat (Triticum aestivum L.) grain transcriptome during early grain-filling.

BACKGROUND: High post-anthesis (p.a) temperatures reduce mature grain weights in wheat and other cereals. However, the causes of this reduction are not entirely known. Control of grain expansion by the maternally derived pericarp of the grain has previously been suggested, although this interaction has not been investigated under high p.a. temperatures. Down-regulation of pericarp localised genes that regulate cell wall expansion under high p.a. temperatures may limit expansion of the encapsulated endosperm due to a loss of plasticity in the pericarp, reducing mature grain weight. Here the effect of high p.a. temperatures on the transcriptome of the pericarp and endosperm of the wheat grain during early grain-filling was investigated via RNA-Seq and is discussed alongside grain moisture dynamics during early grain development and mature grain weight. RESULTS: High p.a. temperatures applied from 6-days after anthesis (daa) and until 18daa reduced the grain's ability to accumulate water, with total grain moisture and percentage grain moisture content being significantly reduced from 14daa onwards. Mature grain weight was also significantly reduced by the same high p.a. temperatures applied from 6daa for 4-days or more, in a separate experiment. Comparison of our RNA-Seq data from whole grains, with existing data sets from isolated pericarp and endosperm tissues enabled the identification of subsets of genes whose expression was significantly affected by high p.a. temperature and predominantly expressed in either tissue. Hierarchical clustering and gene ontology analysis resulted in the identification of a number of genes implicated in the regulation of cell wall expansion, predominantly expressed in the pericarp and significantly down-regulated under high p.a. temperatures, including endoglucanase, xyloglucan endotransglycosylases and a ß-expansin. An over-representation of genes involved in the 'cuticle development' functional pathway that were expressed in the pericarp and affected by high p.a. temperatures was also observed. CONCLUSIONS: High p.a. temperature induced down-regulation of genes involved in regulating pericarp cell wall expansion. This concomitant down-regulation with a reduction in total grain moisture content and grain weight following the same treatment period, adds support to the theory that high p.a. temperatures may cause a reduction in mature grain weight as result of decreased pericarp cell wall expansion.

Indirect parental effects on offspring viability by egg-derived fluids in an external fertilizer.

The capacity for parents to influence offspring phenotypes via nongenetic inheritance is currently a major area of focus in evolutionary biology. Intriguing recent evidence suggests that sexual interactions among males and females, both before and during mating, are important mediators of such effects. Sexual interactions typically extend beyond gamete release, involving both sperm and eggs, and their associated fluids. However, the potential for gamete-level interactions to induce nongenetic parental effects remains under-investigated. Here, we test for such effects using an emerging model system for studying gamete interactions, the external fertilizer Mytilus galloprovincialis. We employed a split-ejaculate design to test whether exposing sperm to egg-derived chemicals (ECs) from a female would affect fertilization rate and offspring viability when those sperm were used to fertilize a different female's eggs. We found separate, significant effects of ECs from non-fertilizing females on both fertilization rate and offspring viability. The offspring viability effect indicates that EC-driven interactions can have nongenetic implications for offspring fitness independent of the genotypes inherited by those offspring. These findings provide a rare test of indirect parental effects driven exclusively by gamete-level interactions, and to our knowledge the first evidence that such effects occur via the gametic fluids of females.