Does sexual experience affect the strength of male mate choice for high‐quality females in Drosophila melanogaster?

Although females are traditionally thought of as the choosy sex, there is increasing evidence in many species that males will preferentially court or mate with certain females over others when given a choice. In the fruit fly, Drosophila melanogaster, males discriminate between potential mating partners based on a number of female traits, including species, mating history, age, and condition. Interestingly, many of these male preferences are affected by the male''s previous sexual experiences, such that males increase courtship toward types of females that they have previously mated with and decrease courtship toward types of females that have previously rejected them. D. melanogaster males also show courtship and mating preferences for larger females over smaller females, likely because larger females have higher fecundity. It is unknown, however, whether this preference shows behavioral plasticity based on the male''s sexual history as we see for other male preferences. Here, we manipulate the sexual experience of D. melanogaster males and test whether this manipulation has any effect on the strength of male mate choice for large females. We find that sexually inexperienced males have a robust courtship preference for large females that is unaffected by previous experience mating with, or being rejected by, females of differing sizes. Given that female body size is one of the most common targets of male mate choice across insect species, our experiments with D. melanogaster may provide insight into how these preferences develop and evolve.     

AT-1.1: A thymus-specific alloantigen of chickens

A thymocyte-specific alloantigen, designated AT (avian thymus) –1.1, has been detected in Cornell C strain (CS) and Obese strain (OS) chickens, the latter being a strain derived from CS which develops a spontaneous form of autoimmune thyroiditis (SAT). Antisera specific for this antigen were developed first in a turkey immunized with thymocytes from an OS chicken and, later, in AT-1.1-negative CS chickens immunized with AT-1.1-positive thymocytes. AT-1.1 was detected in 50–70% of cells in a thymus cell suspension, but was not seen on peripheral blood lymphocytes, erythrocytes, or cells from bursa, spleen, kidney, liver, or brain. It was present on thymocytes of chickens at all ages tested, from 1 day to 6 months of age. AT-1.1 was not detected in six chicken lymphoid tumor cell lines tested, and birds expressing it were found to be negative for the presence of Marek's disease viral antigens. Pedigree studies on 287 (OS × CS)F₂ chickens demonstrated that AT-1.1 is expressed in a dominant or codominant manner, and the gene coding for this antigen was not linked to the B (major histocompatibility) complex. The genetics and tissue distributions of AT-1.1 indicate that it differs from thymus cell surface antigens, avian or mammalian, previously described.     

Metacommunity diversity depends on connectivity and patch arrangement in heterogeneous habitat networks

Connectivity is critical to the maintenance of biodiversity in fragmented landscapes, but its effects differ depending on the arrangement of linkages within a habitat network. Additionally, heterogeneity in habitat quality within the habitat network can alter patterns of diversity at local and regional scales in the metacommunity. Using a controlled experiment we examined the interactive effects of habitat connectivity, network form (linear vs square), and habitat patch quality on a moss‐inhabiting microarthropod community. We fragmented moss habitat while controlling for habitat loss, and altered habitat patch quality by regulating moisture conditions in landscapes differing in patch arrangement. Habitat patch quality had a significant effect on patterns of species richness, extinction, abundance and biomass. The effects of network form on diversity were strongest in heterogeneous landscapes. Gamma and beta diversity were greatest in continuous and linear landscapes. However, linear habitat networks showed marked patch specific edge effects that were detrimental to diversity under heterogeneous conditions. We provide direct evidence that habitat network structure impacts species community properties through mass effects, that are most evident when heterogeneity in habitat patch quality is present within the network. We conclude that habitat quality at the individual patch level and the distribution of high‐quality habitat within the network are important factors affecting biodiversity in metacommunities.     

Future of an "Asymptomatic" T-cell Epitope-Based Therapeutic Herpes Simplex Vaccine

Considering the limited success of the recent herpes clinical vaccine trial [1], new vaccine strategies are needed. Infections with herpes simplex virus type 1 and type 2 (HSV-1 & HSV-2) in the majority of men and women are usually asymptomatic and results in lifelong viral latency in neurons of sensory ganglia (SG). However, in a minority of men and women HSV spontaneous reactivation can cause recurrent disease (i.e., symptomatic individuals). Our recent findings show that T cells from symptomatic and asymptomatic men and women (i.e. those with and without recurrences, respectively) recognize different herpes epitopes. This finding breaks new ground and opens new doors to assess a new vaccine strategy: mucosal immunization with HSV-1 & HSV-2 epitopes that induce strong in vitro CD4 and CD8 T cell responses from PBMC derived from asymptomatic men and women (designated here as "asymptomatic" protective epitopes") could boost local and systemic "natural" protective immunity, induced by wild-type infection. Here we highlight the rationale and the future of our emerging "asymptomatic" T cell epitope-based mucosal vaccine strategy to decrease recurrent herpetic disease.     

A framework to evaluate whether to pool or separate behaviors in a multilayer network

A multilayer network approach combines different network layers,which are connected by interlayer edges,to create a single mathematical object.These networks can contain a variety of information types and represent different aspects of a system.However,the process for selecting which information to include is not always straightforward.Using data on 2 agonistic behaviors in a captive population of monk parakeets(Myiopsitta monachus),we developed a framework for investigating how pooling or splitting behaviors at the scale of dyadic relationships(between 2 individuals)affects individual-and group-level social properties.We designed 2 reference models to test whether randomizing the number of interactions across behavior types results in similar structural patterns as the observed data.Although the behaviors were correlated,the first reference model suggests that the 2 behaviors convey different information about some social properties and should therefore not be pooled.However,once we controlled for data sparsity,we found that the observed measures corresponded with those from the second reference model.Hence,our initial result may have been due to the unequal frequencies of each behavior.Overall,our findings support pooling the 2 behaviors.Awareness of how selected measurements can be affected by data properties is warranted,but nonetheless our framework disentangles these efforts and as a result can be used for myriad types of behaviors and questions.This framework will help researchers make informed and data-driven decisions about which behaviors to pool or separate,prior to using the data in subsequent multilayer network analyses.     

Multimeric Scaffolds Displaying the HIV-1 Envelope MPER Induce MPER-Specific Antibodies and Cross-Neutralizing Antibodies when Co-Immunized with gp160 DNA

Developing a vaccine that overcomes the diversity of HIV-1 is likely to require a strategy that directs antibody (Ab) responses toward conserved regions of the viral Envelope (Env). However, the generation of neutralizing Abs (NAbs) targeting these regions through vaccination has proven to be difficult. One conserved region of particular interest is the membrane proximal external region (MPER) of Env located within the gp41 ectodomain. In order to direct the immune response to this region, the MPER and gp41 ectodomain were expressed separately as N-terminal fusions to the E2 protein of Geobacillus stearothermophilus. The E2 protein acts as a scaffold by self-assembling into 60-mer particles, displaying up to 60 copies of the fused target on the surface. Rabbits were immunized with E2 particles displaying MPER and/or the gp41 ectodomain in conjunction with DNA encoding full-length gp160. Only vaccines including E2 particles displaying MPER elicited MPER-specific Ab responses. NAbs were elicited after two immunizations that largely targeted the V3 loop. To overcome V3 immunodominance in the DNA component, E2 particles displaying MPER were used in conjunction with gp160 DNA lacking hypervariable regions V2, V3, or combined V1V2V3. All rabbits had HIV binding Ab responses and NAbs following the second vaccination. Using HIV-2/HIV-1 MPER chimeric viruses as targets, NAbs were detected in 12/16 rabbits after three immunizations. Low levels of NAbs specific for Tier 1 and 2 viruses were observed in all groups. This study provides evidence that co-immunizing E2 particles displaying MPER and gp160 DNA can focus Ab responses toward conserved regions of Env.     

Prediction of near-term climate change impacts on UK wheat quality and the potential for adaptation through plant breeding

Wheat is a major crop worldwide, mainly cultivated for human consumption and animal feed. Grain quality is paramount in determining its value and downstream use. While we know that climate change threatens global crop yields, a better understanding of impacts on wheat end-use quality is also critical. Combining quantitative genetics with climate model outputs, we investigated UK-wide trends in genotypic adaptation for wheat quality traits. In our approach, we augmented genomic prediction models with environmental characterisation of field trials to predict trait values and climate effects in historical field trial data between 2001 and 2020. Addition of environmental covariates, such as temperature and rainfall, successfully enabled prediction of genotype by environment interactions (G × E), and increased prediction accuracy of most traits for new genotypes in new year cross validation. We then extended predictions from these models to much larger numbers of simulated environments using climate scenarios projected under Representative Concentration Pathways 8.5 for 2050–2069. We found geographically varying climate change impacts on wheat quality due to contrasting associations between specific weather covariables and quality traits across the UK. Notably, negative impacts on quality traits were predicted in the East of the UK due to increased summer temperatures while the climate in the North and South-west may become more favourable with increased summer temperatures. Furthermore, by projecting 167,040 simulated future genotype–environment combinations, we found only limited potential for breeding to exploit predictable G × E to mitigate year-to-year environmental variability for most traits except Hagberg falling number. This suggests low adaptability of current UK wheat germplasm across future UK climates. More generally, approaches demonstrated here will be critical to enable adaptation of global crops to near-term climate change.     

Bioenergetic Constraints on Microbial Hydrogen Utilization in Precambrian Deep Crustal Fracture Fluids

Precambrian Shield rocks host the oldest fracture fluids on Earth, with residence times up to a billion years or more. Water–rock reactions in these fracture systems over geological time have produced highly saline fluids, which can contain millimolar concentrations of H₂. Mixing of these ancient Precambrian fluids with meteoric or palaeo-meteoric water can occur through tectonic fracturing, providing microbial inocula and redox couples to fuel blooms of subsurface growth. Here, we present geochemical and microbiological data from a series of borehole fluids of varying ionic strength (0.6–6.4 M) from the Thompson Mine (Manitoba) within the Canadian Precambrian Shield. Thermodynamic calculations demonstrate sufficient energy for H₂-based catabolic reactions across the entire range of ionic strengths during mixing of high ionic strength fracture fluids with meteoric water, although microbial H₂ consumption and cultivable H₂-utilizing microbes were only detected in fluids of ≤1.9 M ionic strength. This pattern of microbial H₂ utilization can be explained by the higher potential bioenergetic cost of organic osmolyte synthesis at increasing ionic strengths. We propose that further research into the bioenergetics of osmolyte regulation in halophiles is warranted to better constrain the habitability zones of hydrogenotrophic ecosystems in both terrestrial subsurface, including potential future radioactive waste disposal sites, and other planetary body crustal environments, including Mars.     

Cytokine polymorphisms and histologic expression in autopsy studies: contribution of TNF-alpha and TGF-beta 1 to the pathogenesis of autoimmune-associated congenital heart block

Although Abs to SSA/Ro-SSB/La are necessary for the development of congenital heart block (CHB), the low frequency suggests that fetal factors are contributory. Because CHB involves a cascade from inflammation to scarring, polymorphisms of the TNF-alpha promoter region and codons 10 and 25 of the TGF-beta gene were evaluated in 88 children (40 CHB, 17 rash, 31 unaffected siblings) and 74 mothers from the Research Registry for Neonatal Lupus (NL). Cytokine expression was assessed in autopsy material from two fetuses with CHB. Significantly increased frequency of the -308A (high-producer) allele of TNF-alpha was observed in all NL groups compared with controls. In contrast, the TGF-beta polymorphism Leu(10) (associated with increased fibrosis) was significantly higher in CHB children (genotypic frequency 60%, allelic frequency 78%) than unaffected offspring (genotypic frequency 29%, p = 0.016; allelic frequency 56%, p = 0.011) and controls, while there were no significant differences between controls and other NL groups. For the TGF-beta polymorphism, Arg(25), there were no significant differences between NL groups and controls. In fetal CHB hearts, protein expression of TGF-beta, but not TNF-alpha, was demonstrated in septal regions, extracellularly in the fibrous matrix, and intracellularly in macrophage infiltrates. Age-matched fetal hearts from voluntary terminations expressed neither cytokine. TNF-alpha may be one of several factors that amplify susceptibility; however, the genetic studies, backed by the histological data, more convincingly link TGF-beta to the pathogenesis of CHB. This profibrosing cytokine and its secretion/activation circuitry may provide a novel direction for evaluating fetal factors in the development of a robust animal model of CHB as well as therapeutic strategies in humans.     

Induction of a cytotoxic T lymphocyte (CTL) response to plasmid DNA delivered via Lipodine liposomes

We have previously shown that liposome-mediated plasmid DNA immunisation may be a preferred alternative to the use of naked DNA. Lipodine DNA formulations consist of liposomes containing entrapped DNA plasmid by the dehydration-rehydration (DRV) method. Such liposome formulations are distinct from liposomes with externally complexed DNA in that the majority of the DNA is "internal" to the liposome structure and hence protected from DNAase degradation. Previous studies on the immune response induced by DNA vaccines entrapped in Lipodine have focused on the humoural response. In the present study, we have expanded the analysis profile in order to include the cytotoxic T lymphocyte (CTL) component of the immune response. We have analysed the immune response induced by DNA entrapped in Lipodine compared to that induced by DNA alone when delivered subcutaneously, a route of administration not normally inducing significant plasmid DNA mediated immune activation. Our results indicate that delivery of a small dose of plasmid DNA in Lipodine results in an improved antibody response to the plasmid encoded antigen and a strong antigen specific CTL response compared to that induced by DNA delivered alone.