Social group composition modulates the role of last male sperm precedence in post-copulatory sexual selection

In many species, the order in which males mate with a female explains much of the variation in paternity arising from post-copulatory sexual selection. Research in Drosophila suggests that mating order may account for the majority of the variance in male reproductive success. However, the effects of mating order on paternity bias might not be static but could potentially vary with social or environmental factors. To test this idea, we used an existing dataset, collated from an experiment we previously published (Morimoto et al., PLoS One, 11, 2016, e0154468), with the addition of unpublished data from the same experiment. These previous experiments manipulated larval density in Drosophila melanogaster which generated variation in male and female body size, assembled groups of individuals of different sizes, and measured the mating success and paternity share of focal males. The data presented here provides information on each focal male's mating order and the frequency in which focal males remated with same females (‘repetitive matings’). We combined this information with our previously reported focal male reproductive success to partition variance in paternity into male mating order and repetitive matings across groups that differed in the body size composition of males and females. We found, as expected, that male mating order explained a considerable portion of the variance in male paternity. However, we also found that the impact of male mating order on male paternity was influenced by the body size composition of groups. Specifically, males that tended to mate last had a greater paternity advantage, and displayed lower variance, in groups containing a heterogenous mixture male body sizes than in groups with a single male body size. Repetitive mating only had a minor contribution to the variance in male paternity share across all experiments. Overall, our findings contribute to the growing body of research showing that post-copulatory sexual selection is subject to socio-ecological influences.     

Characterization of chitinases and β-1,3-glucanases in grapefruit flavedo during fruit development

Chitinase (EC 3.2.1.14) and β-1,3-glucanase (EC 3.2.1.39) activities in the flavedo of grapefruit ( Citrus paradisi cv. Marsh) were determined at 17 times during the course of fruit development. Chitinase activity is initially high in flavedo, but drops rapidly and is low, although fairly constant throughout the remainder of fruit development. In contrast to chitinase, β-1,3-glucanase activity is lowest in young fruit and increases during development. Western blots of crude flavedo extracts following SDS-PAGE were probed with antibodies raised against purified citrus chitinase and β-1,3-glucanase. Results of immunostaining revealed that changes in the activities of chitinase and β-1,3-glucanase were reflected in the amount of chitinase and glucanase protein present in the extracts. Only a single chitinase band was detected on western blots of crude flavedo extracts, whereas one glucanase band was present in young fruit and a second one appeared later in older fruit. Partial purification of flavedo chitinases and glucanases was performed using extracts prepared from immature and mature fruit for the two enzymes, respectively. Acidic and basic forms of both enzymes were present in the extracts; acidic and basic forms of chitinase were present in nearly equal amounts whereas basic glucanases predominated (91% of total activity). Acidic and basic chitinases differed in substrate specificity as well as products of degradation indicating the heterogeneous nature of the enzymes. Both acidic and basic glucanases required the presence of β-1,3 linkages for activity, were active against both soluble and insoluble β-1,3 glucans and generated similar products.     

Genome‐wide evidence for divergent selection between populations of a major agricultural pathogen

The genetic and environmental homogeneity in agricultural ecosystems is thought to impose strong and uniform selection pressures. However, the impact of this selection on plant pathogen genomes remains largely unknown. We aimed to identify the proportion of the genome and the specific gene functions under positive selection in populations of the fungal wheat pathogen Zymoseptoria tritici. First, we performed genome scans in four field populations that were sampled from different continents and on distinct wheat cultivars to test which genomic regions are under recent selection. Based on extended haplotype homozygosity and composite likelihood ratio tests, we identified 384 and 81 selective sweeps affecting 4% and 0.5% of the 35 Mb core genome, respectively. We found differences both in the number and the position of selective sweeps across the genome between populations. Using a XtX‐based outlier detection approach, we identified 51 extremely divergent genomic regions between the allopatric populations, suggesting that divergent selection led to locally adapted pathogen populations. We performed an outlier detection analysis between two sympatric populations infecting two different wheat cultivars to identify evidence for host‐driven selection. Selective sweep regions harboured genes that are likely to play a role in successfully establishing host infections. We also identified secondary metabolite gene clusters and an enrichment in genes encoding transporter and protein localization functions. The latter gene functions mediate responses to environmental stress, including interactions with the host. The distinct gene functions under selection indicate that both local host genotypes and abiotic factors contributed to local adaptation.     

High temperature effects on photosynthesis and water relations of grain legumes

Effects of high temperature on photosynthesis, and its interaction with water relations in common bean (Phaseolus vulgaris), cowpea (Vigna unguiculata), faba bean (Vicia faba), and five cultivars of field pea (Pisum sativum) were investigated. Responses of all species were compared at 20/15, 30/15, or 30/25 °C day/night, and cowpea and pea were compared at 20/15 and 30/25 °C under well-watered and limited-water conditions. Response of pea to 20/15 and 30/25 °C during flowering was ascertained, and sensitivity of the photosystem of pea and faba bean to 40 °C was determined.High temperature decreased chlorophyll variable fluorescence (F_v), a measure of injury to photosynthesis, in all species except cowpea, which was highly tolerant. Leaf chlorophyll and most measures of growth were favored by high day temperature but not by high night temperature, and photosynthetic rates were enhanced by high temperatures that increased leaf chlorophyll and nitrogen (N) contents. High temperature diminished growth less than water deficiency and increased water use of all three species but only lowered the water potential in faba bean. Water deficiency generally decreased growth, water use, and water potential more at 30/25 °C than at 20/15 °C. Stress from high temperature during flowering of pea decreased all components of yield at maturity, particularly at nodes that flowered latest. Whole-chain photosynthetic activity in thylakoids of pea, faba bean, and wheat (Triticum aestivum) were equally sensitive to high temperature, suggesting that Photosystem Il was the most labile component. The results show that high temperature affects photosynthesis, growth, and water relations of grain legumes, and sensitivity to the stress differs among species and genotypes.     

Phenotypic profiling of mGlu7 knockout mice reveals new implications for neurodevelopmental disorders

Neurodevelopmental disorders are characterized by deficits in communication, cognition, attention, social behavior and/or motor control. Previous studies have pointed to the involvement of genes that regulate synaptic structure and function in the pathogenesis of these disorders. One such gene, GRM7, encodes the metabotropic glutamate receptor 7 (mGlu₇), a G protein‐coupled receptor that regulates presynaptic neurotransmitter release. Mutations and polymorphisms in GRM7 have been associated with neurodevelopmental disorders in clinical populations; however, limited preclinical studies have evaluated mGlu₇ in the context of this specific disease class. Here, we show that the absence of mGlu₇ in mice is sufficient to alter phenotypes within the domains of social behavior, associative learning, motor function, epilepsy and sleep. Moreover, Grm7 knockout mice exhibit an attenuated response to amphetamine. These findings provide rationale for further investigation of mGlu₇ as a potential therapeutic target for neurodevelopmental disorders such as idiopathic autism, attention deficit hyperactivity disorder and Rett syndrome.     

Forest regeneration on Hinewai Reserve,New Zealand: An interview with Hugh Wilson

In 1986 the paths of two men crossed – one who had started a Trust fund to purchase land for conservation and the other who was looking for land to test his hunches about forest regeneration. The two joined forces and the subsequent 30 years saw a growth in both the Trust and the forest such that today it is a 1,500 ha regrowth rainforest with a network of indefatigable supporters.     

Carboxyl-terminal modification alters the subunit interactions and assembly pathways of normal and sickle hemoglobins

Parallel isofocusing studies established that carboxypeptidase A removal of the His-146 (HC3) and Tyr-145 (HC2) residues of heme subunits affected the assembly properties of both Des (A) and Des (S) with heme chains, albeit to differing degrees. Indeed, the rate of Des (A) oligomer dissociation (k ₁), as determined by visible spectroscopy, was 4.3-fold faster than that of its native (A) counterpart. Furthermore, Soret spectral studies have affirmed distinct rates of normal (HbA), sickle (HbS), and Des HbA hemoglobin assembly (k₂) from their and [Des (A)] heme-containing monomers. Matching kinetic analysis of Des (A) and Des (S) chain assembly (with an identical chain) revealed 4.6- and 7.8-fold faster combination rates than those seen for (A) and (S) chains, respectively. This 3-fold disparity in rates strongly supports the critical role of the -6 (A3) residue, and its amino-terminal region, in chain partner recognition and subsequent human hemoglobin assembly.     

Methyl chloride utilising bacteria are ubiquitous in the natural environment

A 17-kDa protein (CadI) was induced by cadmium in Mycobacterium bovis and Mycobacterium tuberculosis. Comparison of the N-terminal sequence from M. bovis CadI with the annotated M. tuberculosis genome database identified Rv2641 as the encoding gene. Long and short promoter fragments from M. bovis cadI were fused to the lacZ reporter gene in pYUB76. Only the long fragment directed cadmium-inducible activity when electroporated into M. bovis. The cadI promoter has potential for both constitutive and inducible expression studies in M. bovis and M. tuberculosis.