Search results for "BD"
showing 10 items of 3363 documents
Evolution of mammal tooth patterns: new insights from a developmental prediction model.
2009
14 pages.; International audience; The study of mammalian evolution is often based on insights into the evolution of teeth. Developmental studies may attempt to address the mechanisms that guide evolutionary changes. One example is the new developmental model proposed by Kavanagh et al. (2007), which provides a high-level testable model to predict mammalian tooth evolution. It is constructed on an inhibitory cascade model based on a dynamic balance of activators and inhibitors, regulating differences in molar size along the lower dental row. Nevertheless, molar sizes in some mammals differ from this inhibitory cascade model, in particular in voles. The aim of this study is to point out arvi…
A new flatworm species of Temnocephala (Rhabdocoela, Temnocephalidae) ectosymbiont on the freshwater crab Valdivia serrata (Decapoda, Trichodactylida…
2020
A new species of temnocephalan is described from the branchial chambers ofValdivia serratain Colombia asTemnocephala ivandarioisp. nov.The most distinctive characters of the new species are in the cirrus and the epidermal ‘excretory’ syncytial plates. In the present study, the terminology to describe the cirrus of species ofTemnocephalais updated. Comparison between the shape of the cirrus of the temnocephalans associated with trichodactylid crabs is also provided.
RNA interference in Lepidoptera: an overview of successful and unsuccessful studies and implications for experimental design.
2011
International audience; Gene silencing through RNA interference (RNAi) has revolutionized the study of gene function, particularly in non-model insects. However, in Lepidoptera (moths and butterflies) RNAi has many times proven to be difficult to achieve. Most of the negative results have been anecdotal and the positive experiments have not been collected in such a way that they are possible to analyze. In this review, we have collected detailed data from more than 150 experiments including all to date published and many unpublished experiments. Despite a large variation in the data, trends that are found are that RNAi is particularly successful in the family Saturniidae and in genes involv…
An early Ca2+ influx is a prerequisite to thaxtomin A-induced cell death in Arabidopsis thaliana cells
2008
International audience; The pathogenicity of various Streptomyces scabies isolates involved in potato scab disease was correlated with the production of thaxtomin A. Since calcium is known as an essential second messenger associated with pathogen-induced plant responses and cell death, it was investigated whether thaxtomin A could induce a Ca 2+ influx related to cell death and to other putative plant responses using Arabidopsis thaliana suspension cells, which is a convenient model to study plant–microbe interactions. A. thaliana cells were treated with micromolar concentrations of thaxto-min A. Cell death was quantified and ion flux variations were analysed from electrophysiological measu…
Increased susceptibility to oxidative damage as a cost of accelerated somatic growth in zebra finches.
2007
1. Most animals do not grow at their maximal rate. This might appear puzzling because the early attainment of a large body size incurs several selective benefits, such as reduced risk of predation and earlier reproductive output. Several hypotheses have been suggested to explain this paradox. Among them, the cost due to high levels of oxidative stress, as the consequence of sustained metabolic activity during growth, has been put forward.
Sperm depletion, male mating behaviour and reproductive ‘time-out' in Gammarus pulex (Crustacea, Amphipoda).
2009
6 pages; International audience; In Gammarus pulex, male–male competition is generally intense because the operational sex ratio (OSR) is strongly biased towards males; however, studies have shown possible fluctuation in this intrasexual competition, which could be caused by sperm depletion, a phenomenon recently found in gammarids. Sperm depletion may also affect male mating behaviour. We therefore tested the influence of sperm depletion on the OSR in G. pulex. Two sets of experiments were conducted: first, to find out the number of sperm in the testis before and after mating events (sperm depletion), and second, to test the implications of sperm depletion for the mating behaviour of male …
Experimental Introgression To Evaluate the Impact of Sex Specific Traits on Drosophila melanogaster Incipient Speciation
2019
AbstractSex specific traits are involved in speciation but it is difficult to determine whether their variation initiates or reinforces sexual isolation. In some insects, speciation depends of the rapid change of expression in desaturase genes coding for sex pheromones. Two closely related desaturase genes are involved in Drosophila melanogaster pheromonal communication: desat1 affects both the production and the reception of sex pheromones while desat2 is involved in their production in flies of Zimbabwe populations. There is a strong asymmetric sexual isolation between Zimbabwe populations and all other “Cosmopolitan” populations: Zimbabwe females rarely copulate with Cosmopolitan males w…
Topical bioassay of Oberon® on Drosophila melanogaster pupae: delayed effects on ovarian proteins, cuticular hydrocarbons and sexual behaviour
2021
International audience; Spiromesifen (Oberon? 240 SC; concentrated solution; Bayer CropScience, Germany) a pesticide derived from spirocyclic tetronic acids, acts mainly though blocking lipid biosynthesis via acetyl-CoA carboxylase. However, its mode of action requires further analyses. This study aims to evaluate the sublethal effects of spiromesifen on the fruit fly Drosophila melanogaster. The treatment was carried out by topical application on newly moulted pupae using two concentrations (LD10 = 21.45 and LD25 = 39.53 ?g a.i./pupa). Our results showed that the developmental duration of larvae and pupae were not significantly affected by treatment. However, spiromesifen caused delayed ef…
Social flexibility and social evolution in mammals: a case study of the African striped mouse (Rhabdomys pumilio)
2011
Environmental change poses challenges to many organisms. The resilience of a species to such change depends on its ability to respond adaptively. Social flexibility is such an adaptive response, whereby individuals of both sexes change their reproductive tactics facultatively in response to fluctuating environmental conditions, leading to changes in the social system. Social flexibility focuses on individual flexibility, and provides a unique opportunity to study both the ultimate and proximate causes of sociality by comparing between solitary and group-living individuals of the same population: why do animals form groups and how is group-living regulated by the environment and the neuro-en…
Presence of uradenia in male adults of the genus Dismegistus (Hemiptera: Heteroptera: Parastrachiidae)
2018
Uradenia, often referred to as paragenital glands, are usually voluminous paired exocrine glands located ventrally in the abdomen mostly on the intersegmental membrane between abdominal segments (= urites) VII-VIII or VIII-IX, depending on sex or the taxon. They have been previously recorded from eight pentatomomorphan families belonging to Coreoidea, Lygaeoidea and Pyrrhocoroidea (Hemiptera: Heteroptera), found either in males, females or both sexes, and were thought to be absent in Pentatomoidea. We report here the first instance of uradenia in a pentatomoid genus, the African Dismegistus Amyot & Serville, 1843 (Parastrachiidae). Only the male adult possesses uradenia located on the i…