30 research outputs found
The developmental basis of caste evolution in ants
No full textPhenotypic plasticity is the ability for a single genotype to give rise to alternative adaptive phenotypes in response to environmental conditions facilitating their survival. In some cases, environmental conditions can influence the course of development of an organism, leading to the induction of novel phenotypic variation, the raw materials for selection in evolution. Although this fact has the potential to unify the disparate fields of ecology, development and evolution, we have only begun to investigate the underlying molecular mechanisms that translate the environment into phenotypic diversity. Ants are highly plastic; during development a single genotype can give rise to an array of alternative phenotypes related to dramatic differences in morphology, longevity, reproduction and behavior. This environmental sensitivity is the basis for the diversity of complex ant caste systems. Here, I used ant development of the hyperdiverse genera Pheidole and Camponotus as models to investigate my major goal, which is to understand how ecology (environment) acts on development, generating morphological variation, which can then lead to morphological diversification and evolution. The first specific goal (Chapter 2) of my thesis is to investigate the hormonal and developmental genetic basis underlying the evolution of novel worker ant subcastes. Specifically, the genus Pheidole is composed of over 1000 species, all of which comprise a complex worker caste system of minor workers and soldiers. In a hand full of these species, there exists an additional novel worker subcaste, the supersoldier. Through phylogenetic and developmental genetic analysis, I determined that this subcaste has evolved in parallel in different species. I then discovered through field observations and hormonal manipulations that there exists an ancestral developmental potential in this group: all Pheidole species have the hidden capacity to produce supersoldiers through environmental induction, the recurrence of which can lead to their evolution. The second specific goal of my thesis (Chapter 4) is to investigate the epigenetic mechanisms that translate environmental conditions into morphological variation within castes. Specifically, I investigated the involvement of DNA methylation in generating continuous sizing in the worker caste of the genus Camponotus. I discovered that DNA methylation is responsible for generating a continuous distribution of worker size and that one of its primary targets is the gene Egfr. Furthermore, the methylation level of Egfr is associated with quantitative variation in worker size and pharmacological inhibition of EGFR signaling demonstrated that this pathway is capable of generating the continuous distribution of size found within this caste. DNA methylation is an epigenetic mechanism that is known to cause transgenerational inheritance and therefore it can facilitate the evolution of environmentally generated quantitative variation. Collectively, the results of my thesis show how the environment acts on development through the integration of hormones, genes and epigenetic mechanisms to generate phenotypic variation for selection to act on. Perhaps we are coming closer to a point in time in evolutionary theory when we can say that the environment is as important in generating phenotypic variation as it is in the process of selection.La plasticité phénotypique est l'habileté d'un génotype unique de produire des phénotypes adaptatifs alternes en réponse à des conditions environnementales facilitant leur survie. Dans certains cas, les conditions environnementales peuvent influencer le cours du développement d'un organisme, menant à l'induction d'une variation phénotypique nouvelle, qui est la matière brute pour la sélection en évolution. Bien que ce fait ait le potentiel d'unifier les champs distincts de l'écologie, du développement et de l'évolution, on commence seulement à étudier les mécanismes moléculaires fondamentaux qui traduisent l'environnement en diversité phénotypique. Les fourmis démontrent une grande plasticité phénotypique; durant le développement, un génotype unique peut produire une diversité de phénotypes adaptatifs qui démontrent des différences dramatiques de morphologie, de longévité, de reproduction et de comportement. Cette sensibilité environnementale est à la base de la diversité des systèmes complexes de castes chez les fourmis. Ici, j'ai utilisé le développement des genres hyperdiversifiés Pheidole et Camponotus comme modèles pour investiguer mon but principal, qui est de comprendre comment l'écologie (l'environnement) agit sur le développement, en générant de la variation morphologique qui peut par la suite mener à une évolution morphologique. Le premier objectif spécifique de ma thèse (Chapitre 2) est d'investiguer les bases hormonales et du développement des nouvelles sous-castes ouvrières chez les fourmis. Plus spécifiquement, le genre Pheidole est composé de plus de 1000 espèces, toutes démontrant un système de castes ouvrières complexe comprenant des ouvrières mineurs et des soldates. Chez un petit groupe de ces espèces, il existe une caste ouvrière additionnelle, la supersoldate. En utilisant des analyses phylogénétiques et de génétique du développement, j'ai déterminé que cette sous-caste a évolué en parallèle chez les différentes espèces. J'ai par la suite découvert, par des observations sur le terrain et des manipulations hormonales, qu'il existe un potentiel ancestral de développement dans ce groupe: toutes les espèces de Pheidole ont une capacité cachée de produire des supersoldates par induction environnementale, cette récurrence pouvant mener à leur évolution. Le second objectif spécifique de ma thèse (Chapitre 4) est d'investiguer les mécanismes épigénétiques qui traduisent les conditions environnementales en variation morphologique entre les castes. Plus spécifiquement, j'ai investigué le rôle de la méthylation de l'ADN dans l'élaboration d'une distribution de taille continue chez la caste ouvrière de Camponotus. J'ai découvert que la méthylation de l'ADN génère une distribution continue de taille chez la caste ouvrière et que l'une de ses cibles principales est le gène Egfr. D'ailleurs, le niveau de méthylation de Egfr est associé à une variation quantitative de la taille des ouvrières et une inhibition pharmacologique de la signalisation EGFR a démontré que cette voie de signalisation est capable de générer la distribution continue des tailles dans cette caste. La méthylation de l'ADN est un mécanisme épigénétique qui est connu pour causer une héritabilité transgénérationelle et donc, elle peut faciliter l'évolution d'une variation quantitative générée par l'environnement. Collectivement, les résultats de ma thèse montrent comment l'environnement agit sur le développement par l'intégration des hormones, des gènes et des mécanismes épigénétiques pour générer de la variation phénotypique sur laquelle la sélection naturelle peut agir par la suite. Peut-être que nous nous rapprochons d'un moment où la théorie de l'évolution peut proposer que l'environnement soit également important pour générer de la variation phénotypique qu'il peut l'être au cours du processus de sélection
How a growing organismal perspective is adding new depth to integrative studies of morphological evolution
No full textLack of interruption of the gene network underlying wing polyphenism in an early‐branching ant genus
No full textInternational audienc
Interruption points in the wing gene regulatory network underlying wing polyphenism evolved independently in male and female morphs in Cardiocondyla ants
No full textInternational audienc
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No full textNot AvailableMicrobial diversity is a very crucial component for the soil health maintenance. The present study investigatedthe effects of nanozeolite on bacterial diversity of soil from the agriculturalfield which was under 4-yearfieldtrial with wheat crop. Nanozeolite was amended in the treated plot whereas, the control plot did not receive anytreatment. The bacterial population was targeted through the hypervariable (V3) region, which is a part of16SrDNA. The 16SrDNA region is a conserved region among the bacterial species, but to investigate the diversityamong the same species the hypervariable region are the best suited sequences. More than 1 million reads pertreatment revealed very high levels of diversity. The majority of the sequences were attribute to theProteobacteria (about 23–25%), 15% and 30–35%fitted into Actinobacteria and unknown phylum, respectively.Significant higher abundances of bacterial species with NZ treatment encompassed the population associatedwith nutrient cycling, residue decomposition and xenobiosis. The alpha diversity index also indicated betterdiversity and evenness within the treated soil than untreated soil. Ourfindings support the importance of na-nozeolite for better survival of soil microorganisms especially bacteria.1. IntroductionMicrobial community in soil is very diverse where the maximumpercent is covered by prokaryotic populations. Just 1 g of soil housesabout 10 billion microorganisms and thousands of different types ofspecies (Knietch et al., 2003). Soil microbial activity has the capacity toreverse the deteriorating soil properties, since it participates in themajor biogeochemical cycling. Therefore, soil microbial diversity is themain focus for the sustainable agricultural practices in long term(Brown et al., 2002; FAO, 2012). Global adoption of soil conservationpractices in agriculture is necessary to reverse soil degradation, and tomaintain soil fertility and soil biodiversity. Zeolites are naturally oc-curring crystalline aluminum silicates which assist in water infiltrationand retention in soil due to its porous property and the suction exertedby it. It can retain nutrients and hence supposed to improve crop yield(Prasad et al., 2014). The bulk size of nanozeolite limits some extra-ordinary properties which are shown by their nanosized (0–100 nm)counterparts. The nanozeolite has higher cation exchange capacity,surface area, ion adsorption and complexation etc. (Mukhopadhyay,2014).The traditional techniques allow cultivation of about less than 1 %of total microbial population which limits the study based on it (Schlossand Handelsman, 2003). The limitation of cultivable techniques can bedelineated through the application of metagenomic approaches whichcan be applied to study a range of soil environments (Rajendhran J,Gunasekaran, 2008; Handelsman, 1998). The present study in-vestigated the effect of nanozeolite on bacterial population of agri-culturefield through 16SrDNA targeted soil metagenome sequencing.Further research can be done to understand the effect of nanozeolite onthe microbial communities under different conditions, especially fordifferent soil types.2. Materials and methods2.1. Details of study areaThe study was performed in afield experiment on wheat system,established in the winters of 2014–2015 at Norman E. Borlogue Crophttps://doi.org/10.1016/j.bcab.2019.101249Received 14 June 2019; Received in revised form 10 July 2019; Accepted 13 July 2019*Corresponding author. ICAR- Vivekananda Parvatiya Krishi Anusandhan Sansthan, Almora, Uttarakhand, india.E-mail address:[email protected](P. Khati).Biocatalysis and Agricultural Biotechnology 20 (2019) 101249Available online 15 July 20191878-8181/ © 2019 Elsevier Ltd. All rights reserved.TNot Availabl
Next generation CRISPR/Cas9 transcriptional activation in<i>Drosophila</i>using flySAM
No full textAbstractCRISPR/Cas9-based transcriptional activation (CRISPRa) has recently emerged as a powerful and scalable technique for systematic over-expression genetic analysis inDrosophila melanogaster.We present flySAM, a potent new tool forin vivoCRISPRa, which offers a major improvement over existing strategies in terms of effectiveness, scalability, and ease-of-use. flySAM outperforms existingin vivoCRISPRa strategies, and approximates phenotypes obtained using traditional Gal4-UAS over-expression. Further, because flySAM typically only requires a single sgRNA, it dramatically improves scalability. We use flySAM to demonstrate multiplexed CRISPRa, which has not been previously shownin vivo.In addition, we have simplified the experimental usage of flySAM by creating a single vector encoding both the UAS:Cas9-activator and the sgRNA, allowing for inducible CRISPRa in a single genetic cross. flySAM will thus replace previous CRISPRa strategies as the basis of our growing genome-wide transgenic over-expression resource, TRiP-OE.</jats:p
Next-generation CRISPR/Cas9 transcriptional activation in <i>Drosophila</i> using flySAM
No full textSignificance
We present flySAM, a potent system for Cas9-based transcriptional activation (CRISPRa) in
Drosophila
. flySAM greatly improves on existing in vivo CRISPRa techniques in terms of potency, scalability, and ease of use, and provides a simple and general method for conducting overexpression experiments and screens. flySAM will now serve as the basis for our growing collection of publicly available CRISPRa transgenic fly lines.
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