| 1. |
- Enault, Sébastien, et al.
(författare)
-
Molecular footprinting of skeletal tissues in the catshark Scyliorhinus canicula and the clawed frog Xenopus tropicalis identifies conserved and derived features of vertebrate calcification.
- 2015
-
Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the evolutionary emergence and subsequent diversification of the vertebrate skeleton requires a comprehensive view of the diverse skeletal cell types found in distinct developmental contexts, tissues, and species. To date, our knowledge of the molecular nature of the shark calcified extracellular matrix, and its relationships with osteichthyan skeletal tissues, remain scarce. Here, based on specific combinations of expression patterns of the Col1a1, Col1a2, and Col2a1 fibrillar collagen genes, we compare the molecular footprint of endoskeletal elements from the chondrichthyan Scyliorhinus canicula and the tetrapod Xenopus tropicalis. We find that, depending on the anatomical location, Scyliorhinus skeletal calcification is associated to cell types expressing different subsets of fibrillar collagen genes, such as high levels of Col1a1 and Col1a2 in the neural arches, high levels of Col2a1 in the tesserae, or associated to a drastic Col2a1 downregulation in the centrum. We detect low Col2a1 levels in Xenopus osteoblasts, thereby revealing that the osteoblastic expression of this gene was significantly reduced in the tetrapod lineage. Finally, we uncover a striking parallel, from a molecular and histological perspective, between the vertebral cartilage calcification of both species and discuss the evolutionary origin of endochondral ossification.
|
|
| 2. |
- Silva, Willian T. A. F., 1987-, et al.
(författare)
-
Evolution of plasticity in production and transgenerational inheritance of small RNAs under dynamic environmental conditions
- 2021
-
Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 17:5
-
Tidskriftsartikel (refereegranskat)abstract
- In a changing environment, small RNAs (sRNAs) play an important role in the post-transcriptional regulation of gene expression and can vary in abundance depending on the conditions experienced by an individual (phenotypic plasticity) and its parents (non-genetic inheritance). Many sRNAs are unusual in that they can be produced in two ways, either using genomic DNA as the template (primary sRNAs) or existing sRNAs as the template (secondary sRNAs). Thus, organisms can evolve rapid plastic responses to their current environment by adjusting the amplification rate of sRNA templates. sRNA levels can also be transmitted transgenerationally by the direct transfer of either sRNAs or the proteins involved in amplification. Theory is needed to describe the selective forces acting on sRNA levels, accounting for the dual nature of sRNAs as regulatory elements and templates for amplification and for the potential to transmit sRNAs and their amplification agents to offspring. Here, we develop a model to study the dynamics of sRNA production and inheritance in a fluctuating environment. We tested the selective advantage of mutants capable of sRNA-mediated phenotypic plasticity within resident populations with fixed levels of sRNA transcription. Even when the resident was allowed to evolve an optimal constant rate of sRNA production, plastic amplification rates capable of responding to environmental conditions were favored. Mechanisms allowing sRNA transcripts or amplification agents to be inherited were favored primarily when parents and offspring face similar environments and when selection acts before the optimal level of sRNA can be reached within the organism. Our study provides a clear set of testable predictions for the evolution of sRNA-related mechanisms of phenotypic plasticity and transgenerational inheritance.Author summarySmall RNAs (sRNA) are produced by a wide range of organisms, from bacteria to plants and animals. These molecules are involved in the response to environmental stress (e.g., temperature, pathogens) and can be transmitted across generations. We developed a model to explore the dynamics of sRNA production (phenotypic plasticity) and inheritance in a fluctuating environment. We tested whether different sRNA mutants can invade a population where individuals produce sRNA at a constant optimal transcription rate. In our simulations, plastic amplification rates capable of responding to environmental conditions were favored and the transmission of sRNA transcripts or amplification agents across generations was particularly advantageous when parents and offspring faced similar environments. sRNA amplification alone is not favored except when optimal sRNA levels are not reached within a generation. Our model provides novel predictions for the molecular mechanisms of sRNA production and guidance for future empirical studies on mutations that impair the mechanisms of sRNA production and their fitness consequences.
|
|
| 3. |
|
|
| 4. |
- Silva, Willian T. A. F., 1987-
(författare)
-
Non-genetic processes in development and heredity
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a swiftly increasing amount of empirical evidence that non-genetic factors, such as DNA methylation and small RNAs, play an important role not only in development but also in heredity and, therefore, evolutionary dynamics. One of the most interesting aspects of non-genetic processes is their responsiveness to environmental conditions, which has been shown to affect not only the phenotype and fitness of the individuals directly exposed to the stimulus, but also their offspring even when the stimulus is no longer present, indicating that the transmission of non-genetic factors across generations might work analogously to immunization against recurring conditions. In this thesis, I explored the effects and consequences of non-genetic processes in development and heredity, from both theoretical and experimental perspectives. In Article I, I created a mathematical model of DNA methylation dynamics during the maternal-to-zygotic transition, leading to the zygotic genome activation. I found that there is a developmental constraint on the transition between different cell lineages, with an increasing flexibility of active methylation and decreasing flexibility of maintenance (de-)methylation. In Article II, we explored the dynamics of small RNA production throughout development, including their amplification, transgenerational transmission and responsiveness to environmental conditions. Responsiveness of small RNA production resulted in greater benefits when soma and germline are both responsive, especially in highly correlated environmental conditions. In Article III, I carried out experiments on zebrafish to explore the effects of the male social environment on sperm production in terms of sperm morphology and DNA quality. Males exposed to different social treatments produced sperm with different morphologies and DNA integrity levels. In Article IV, we used the same experimental design to look at the effects of the male social environment on offspring development in terms of differential gene expression patterns. Males exposed to different social treatments sired offspring that showed different expression patterns of genes involved in post-transcriptional processes of gene expression regulation. Our findings shed light on the importance of non-genetic processes in development and heredity and contributes to the current knowledge about which and how non-genetic mechanisms can potentially affect evolutionary dynamics.
|
|
| 5. |
|
|
| 6. |
- Silva, Willian T. A. F., 1987-, et al.
(författare)
-
The effects of male social environment on sperm phenotype and genome integrity
- 2019
-
Ingår i: Journal of Evolutionary Biology. - : John Wiley & Sons. - 1010-061X .- 1420-9101. ; 32:6, s. 535-544
-
Tidskriftsartikel (refereegranskat)abstract
- Sperm function and quality are primary determinants of male reproductive performance and hence fitness. The presence of rival males has been shown to affect ejaculate and sperm traits in a wide range of taxa. However, male physiological conditions may not only affect sperm phenotypic traits but also their genetic and epigenetic signatures, affecting the fitness of the resulting offspring. We investigated the effects of male-male competition on sperm quality using TUNEL assays and geometric morphometrics in the zebrafish, Danio rerio. We found that the sperm produced by males exposed to high male-male competition had smaller heads but larger midpiece and flagellum than sperm produced by males under low competition. Head and flagella also appeared less sensitive to the osmotic stress induced by activation with water. In addition, more sperm showed signals of DNA damage in ejaculates of males under high competition. These findings suggest that the presence of a rival male may have positive effects on sperm phenotypic traits but negative effects on sperm DNA integrity. Overall, males facing the presence of rival males may produce faster swimming and more competitive sperm but this may come at a cost for the next generation.
|
|
