Evolution and diversity of TGF-beta pathways are linked with novel developmental and behavioural trait

Transforming growth factor β (TGF-β) signalling is essential for numerous biological functions. It is a highly conserved pathway found in all metazoans including the nematode Caenorhabditis elegans, which has also been pivotal in identifying many components. Utilising a comparative evolutionary approach, we explored TGF-β signalling in nine nematode species and revealed striking variability in TGF-β gene frequency across the lineage. Of the species analysed, gene duplications in the DAF-7 pathway appear common with the greatest disparity observed in Pristionchus pacificus. Specifically, multiple paralogues of daf-3, daf-4 and daf-7 were detected. To investigate this additional diversity, we induced mutations in 22 TGF-β components and generated corresponding double, triple and quadruple mutants revealing both conservation and diversification in function. Although, the DBL-1 pathway regulating body morphology appears highly conserved, the DAF-7 pathway exhibits functional divergence, notably in some aspects of dauer formation. Furthermore, the formation of the phenotypically plastic mouth in P. pacificus is partially influenced through TGF-β with the strongest effect in Ppa-tag-68. This appears important for numerous processes in P. pacificus but has no known function in C. elegans. Finally, we observe behavioural differences in TGF-β mutants including in chemosensation and the establishment of the P. pacificus kin-recognition signal. Thus, TGF-β signalling in nematodes represents a stochastic genetic network capable of generating novel functions through the duplication and deletion of associated genes

Sex or cannibalism: Polyphenism and kin recognition control social action strategies in nematodes

Resource polyphenisms, where single genotypes produce alternative feeding strategies in response to changing environments, are thought to be facilitators of evolutionary novelty. However, understanding the interplay between environment, morphology, and behavior and its significance is complex. We explore a radiation of Pristionchus nematodes with discrete polyphenic mouth forms and associated microbivorous versus cannibalistic traits. Notably, comparing 29 Pristionchus species reveals that reproductive mode strongly correlates with mouth-form plasticity. Male-female species exhibit the microbivorous morph and avoid parent-offspring conflict as indicated by genetic hybrids. In contrast, hermaphroditic species display cannibalistic morphs encouraging competition. Testing predation between 36 co-occurring strains of the hermaphrodite P. pacificus showed that killing inversely correlates with genomic relatedness. These empirical data together with theory reveal that polyphenism (plasticity), kin recognition, and relatedness are three major factors that shape cannibalistic behaviors. Thus, developmental plasticity influences cooperative versus competitive social action strategies in diverse animals

Improving Hydrophysical Properties Quality of Compost

Abstract: Soilless culture is in the process of becoming an important part of green houses. Two types of material used as horticultural materials, compost and perlite, were chosen to investigate to somewhat one can improve their hydrophysical properties and hence its quality. Different mixture ratios between two materials were carried out as follows: 100:0, 75:25, 50:50, 25:75 and 0:100 , compost : perlite. The different hydrophysical properties were determined. The obtained results revealed that increasing perlite in mixture could improve total pore space, free air space and easily available water. Increasing perlite has a significant negative effect on water buffering capacity in mixture, while it improves hydraulic conductivity after mixing with compost at all the studied ratios. The highest water retention capacity values were obtained from ratios 75:25 (82.78 %), followed by 50:50 (76.62 %) and 25:75 (48.97 %) compost : perlite ratio , respectively. Improvement of hydrophysical properties of compost through enriching by perlite led to more effective irrigation and fertilization strategies and develop structures that could hold adequate water supply for plant and enough and good aeration

The association between social capital and mental health and behavioural problems in children and adolescents: an integrative systematic review

Background Mental health is an important component of overall health and wellbeing and crucial for a happy and meaningful life. The prevalence of mental health problems amongst children and adolescent is high; with estimates suggesting 10-20% suffer from mental health problems at any given time. These mental health problems include internalising (e.g. depression and social anxiety) and externalising behavioural problems (e.g. aggression and anti-social behaviour). Although social capital has been shown to be associated with mental health/behavioural problems in young people, attempts to consolidate the evidence in the form of a review have been limited. This integrative systematic review identified and synthesised international research findings on the role and impact of family and community social capital on mental health/behavioural problems in children and adolescents to provide a consolidated evidence base to inform future research and policy development. Methods Nine electronic databases were searched for relevant studies and this was followed by hand searching. Identified literature was screened using review-specific inclusion/exclusion criteria, the data were extracted from the included studies and study quality was assessed. Heterogeneity in study design and outcomes precluded meta-analysis/meta-synthesis, the results are therefore presented in narrative form. Results After screening, 55 studies were retained. The majority were cross-sectional surveys and were conducted in North America (n = 33); seven were conducted in the UK. Samples ranged in size from 29 to 98,340. The synthesised results demonstrate that family and community social capital are associated with mental health/behavioural problems in children and adolescents. Positive parent–child relations, extended family support, social support networks, religiosity, neighbourhood and school quality appear to be particularly important. Conclusions To date, this is the most comprehensive review of the evidence on the relationships that exist between social capital and mental health/behavioural problems in children and adolescents. It suggests that social capital generated and mobilised at the family and community level can influence mental health/problem behaviour outcomes in young people. In addition, it highlights key gaps in knowledge where future research could further illuminate the mechanisms through which social capital works to influence health and wellbeing and thus inform policy development

Adult Influence on Juvenile Phenotypes by Stage-Specific Pheromone Production

Many animal and plant species respond to population density by phenotypic plasticity. To investigate if specific age classes and/or cross-generational signaling affect density-dependent plasticity, we developed a dye-based method to differentiate co-existing nematode populations. We applied this method to Pristionchus pacificus, which develops a predatory mouth form to exploit alternative resources and kill competitors in response to high population densities. Remarkably, adult, but not juvenile, crowding induces the predatory morph in other juveniles. High-performance liquid chromatography-mass spectrometry of secreted metabolites combined with genetic mutants traced this result to the production of stage-specific pheromones. In particular, the P. pacificus-specific di-ascaroside#1 that induces the predatory morph is induced in the last juvenile stage and young adults, even though mouth forms are no longer plastic in adults. Cross-generational signaling between adults and juveniles may serve as an indication of rapidly increasing population size, arguing that age classes are an important component of phenotypic plasticity

Dissecting the genetic architecture underlying mouth dimorphism in Pristionchus pacificus identifies cis-regulatory variation in a supergene locus

Developmental (phenotypic) plasticity describes the property of a genotype to respond to environmental variation by producing distinct phenotypes. In Pristionchus pacificus, the mouth form is developmentally plastic, resulting in two alternative mouth forms: the eurystomatous (Eu) predatory form has two strong teeth, whereas the alternative stenostomatous (St) form has a single tooth and is bacteriovorus. The switch between the two forms is environmentally sensitive, and a previous forward genetic approach showed a key switch function for the sulfatase-coding gene eud-1, mutations in which result in all-St worms. In this study we used P. pacificus natural isolates with different Eu/St ratios to generate Recombinant Inbred Lines (RILs), and performed Quantitative Trait Locus (QTL) analysis to dissect the genetic architecture underlying mouth dimorphism in P. pacificus. Our result showed the involvement of one major locus on the X chromosome, spanning a recently described multi- gene locus containing eud-1, its paralog, and two more genes encoding α-N-acetylglucosaminidases (nag), all of which were shown to be involved in mouth form regulation. RNA-seq analysis of parental strains revealed 40% higher expression of eud-1 in the high Eu parental strain, and CRISPR-Cas9 mutants of the two sulftases paralogous in the high Eu parental strain showed a complete switch to the St form. With the absence of non-synonymous substitutions in eud-1 between the parental lines, we used CRISPR-Cas9 technology to perform variant swapping in the eud-1 regulatory region to define potential causative SNPs behind the mouth-form dimorphism. Our experimental analysis identified variations in different cis-regulatory components of eud-1. Copy number differences in a potential Forkhead transcription factor binding site within the promoter/enhancer region, besides a SNP in the eud-1 first intron between the parental lines caused differences in mouth-form ratios phenotype. Mutant lines showed an additive effect of these cis-regulatory elements, with a systematic change in the mouth-form phenotype and downregulation of eud-1 expression. Currently, we are using CRISPR-Cas9 technology to examine the potential involvement of various Forkhead genes in controlling eud-1 expression, while also expanding our analysis to test variations in the causative region within 30 more P. pacificus natural isolates

The genetics of phenotypic plasticity in nematode feeding structures

Phenotypic plasticity has been proposed as an ecological and evolutionary concept. Ecologically, it can help study how genes and the environment interact to produce robust phenotypes. Evolutionarily, as a facilitator it might contribute to phenotypic novelty and diversification. However, the discussion of phenotypic plasticity remains contentious in parts due to the absence of model systems and rigorous genetic studies. Here, we summarize recent work on the nematode Pristionchus pacificus, which exhibits a feeding plasticity allowing predatory or bacteriovorous feeding. We show feeding plasticity to be controlled by developmental switch genes that are themselves under epigenetic control. Phylogenetic and comparative studies support phenotypic plasticity and its role as a facilitator of morphological novelty and diversity