Search results for "development."

2020

Abstract The filamentous fungus Neurospora crassa, a model microbial eukaryote, has a life cycle with many features that make it suitable for studying experimental evolution. However, it has lacked a general tool for estimating relative fitness of different strains in competition experiments. To remedy this need, we constructed N. crassa strains that contain a modified csr-1 locus and developed an assay for detecting the proportion of the marked strain using a post PCR high resolution melting assay. DNA extraction from spore samples can be performed on 96-well plates, followed by a PCR step, which allows many samples to be processed with ease. Furthermore, we suggest a Bayesian approach for…

Marked Neurospora crassa strains for competition experiments and Bayesian methods for fitness estimates

2019

AbstractThe filamentous fungusNeurospora crassa, a model microbial eukaryote, has a life cycle with many features that make it suitable for studying experimental evolution. However, it has lacked a general tool for estimating relative fitness of different strains in competition experiments. To remedy this need, we constructedN. crassastrains that contain a modifiedcsr-1locus and developed an assay for detecting the proportion of the marked strain using a post PCR high resolution melting assay. DNA extraction from spore samples can be performed on 96-well plates, followed by a PCR step, which allows many samples to be processed with ease. Furthermore, we suggest a Bayesian approach for estim…

THE DISTRIBUTION OF MUTATIONAL FITNESS EFFECTS OF PHAGE φX174 ON DIFFERENT HOSTS

2012

Adaptation depends greatly on the distribution of mutation fitness effects (DMFE), but the phenotypic expression of mutations is often environment dependent. The environments faced by multihost pathogens are mostly governed by their hosts and therefore measuring the DMFE on multiple hosts can inform on the likelihood of short-term establishment and longer term adaptation of emerging pathogens. We explored this by measuring the growth rate of 36 mutants of the lytic bacteriophage φX174 on two host backgrounds, Escherichia coli (EcC) and Salmonella typhimurium (StGal). The DMFE showed higher mean and variance on EcC than on StGal. Most mutations were either deleterious or neutral on both host…

2013

Vertebrate hosts often defend themselves against several co-infecting parasite genotypes simultaneously. This has important implications for the ecological dynamics and the evolution of host defence systems and parasite strategies. For example, it can drive the specificity of the adaptive immune system towards high genotype-specificity or cross-reactivity against several parasite genotypes depending on the sequence and probability of re-infections. However, to date, there is very little evidence on these interactions outside mammalian disease literature. In this study we asked whether genotype-specific or cross-reactive responses dominate in the adaptive immune system of a fish host towards…

Epigenetic control of phenotypic plasticity in a filamentous fungus Neurospora crassa

2016

AbstractPhenotypic plasticity is the ability of a genotype to produce different phenotypes under different environmental or developmental conditions. Phenotypic plasticity is an ubiquitous feature of living organisms, and is typically based on variable patterns of gene expression. However, the mechanisms by which gene expression is influenced and regulated during plastic responses are poorly understood in most organisms. While modifications to DNA and histone proteins have been implicated as likely candidates for generating and regulating phenotypic plasticity, specific details of each modification and its mode of operation have remained largely unknown. In this study, we investigated how e…

The genetic basis of balanced polymorphism in Philaenus (Homoptera)

2009

In Philaenus spumarius (Homoptera), colour polymorphism is mainly determined by a series of allelic genes. The dominance and co-dominance relationships of the following seven alleles were analysed: T (trilineatus), M (marginellus), F (flavicollis-F), L (lateralis), C (flavicollis-C, gibbus and leucocephalus), O (quadrimaculatus, albomaculatus and leucophthalmus) and t (typicus). The colour phenotypes are indicated in brackets. On the basis of partly direct and partly indirect evidence, T was found to be the top dominant and t the bottom recessive allele in the female sex. In the males, T is also the top dominant, but t comes second in the hierarchy. Conclusive evidence of the dominance of T…

Gentics of hilanenus colour polymorphism: the 28 genotypes.

2009

SHAPE MATTERS: EFFECT OF POINT MUTATIONS ON RNA SECONDARY STRUCTURE

2013

A suitable model to dive into the properties of genotype-phenotype landscapes is the relationship between RNA sequences and their corresponding minimum free energy secondary structures. Relevant issues related to molecular evolvability and robustness to mutations have been studied in this framework. Here, we analyze the one-mutant neighborhood of the predicted secondary structure of 46 different RNAs, including tRNAs, viroids, larger molecules such as Hepatitis-δ virus, and several random sequences. The probability distribution of the effect of point mutations in linear structural motifs of the secondary structure is well fit by Pareto or Lognormal probability distributions functions, indep…

Sexual antagonism for testosterone maintains multiple mating behaviour

2011

Summary 1. The persistence of multiple mating remains one of the fundamental questions in evolutionary biology. In theory, multiple mating is predicted to improve female fitness cumulatively through direct and ⁄ or genetic benefits. However, intra-locus sexual conflicts may potentially constrain or even eliminate these benefits owing to the gender load imposed by sexually antagonistic selection. 2. Here, we tested whether sexually antagonistic selection can maintain the variance in multiple mating behaviour of bank voles (Myodes glareolus) by manipulating the hormone testosterone through artificial selection in the laboratory. Among mammals, testosterone is a sexually dimorphic fitness-rela…

EVALUATION OF ELEVATED PLOIDY AND ASEXUAL REPRODUCTION AS ALTERNATIVE EXPLANATIONS FOR GEOGRAPHIC PARTHENOGENESIS IN EUCYPRIS VIRENS OSTRACODS

2009

Transitions from sexual to asexual reproduction are often coupled with elevations in ploidy. As a consequence, the importance of ploidy per se for the maintenance and spread of asexual populations is unclear. To examine the effects of ploidy and asexual reproduction as independent determinants of the success of asexual lineages, we sampled diploid sexual, diploid asexual, and triploid asexual Eucypris virens ostracods across a European wide range. Applying nuclear and mitochondrial markers, we found that E. virens consists of genetically highly differentiated diploid sexual populations, to the extent that these sexual clades could be considered as cryptic species. All sexual populations wer…