Biology subjects

Pires da Silva, A.

Publications and source records attributed to Pires da Silva, A..

3 recordsLinked to original sources

bioRxiv2018

Liposome-based transfection enhances RNAi and CRISPR-mediated mutagenesis in non-model nematode systems

Nematodes belong to one of the most diverse animal phyla. However, functional genomic studies in nematodes, other than in a few species, have often been limited in their reliability and success. Here we report that by combining liposome-based technology with microinjection, we were able to establish a wide range of genomic techniques in the newly described nematode genus Auanema. The method also allowed heritable changes in dauer larvae of Auanema, despite the immaturity of the gonad at the time of the microinjection. As proof of concept for potential functional studies in other nematode species, we also induced RNAi in the free-living nematode Pristionchus pacificus and targeted the human parasite Strongyloides stercoralis.

developmental biology↗

bioRxiv2018

Sensory neurons control heritable adaptation to stress through germline reprogramming

Maternal neuronal signaling has been reported to program adaptive changes in offspring physiology in diverse organisms [1, 2]. However, the mechanisms for the inheritance of adaptive maternal effects through the germline are largely unknown. In the nematode Auanema freiburgensis, stress-resistance and sex of the offspring depend on environmental cues experienced by the mother. Maternal sensing of high population densities results in the production of stress-resistant larvae (dauers) that develop into hermaphrodites. Ablation of the maternal ASH chemosensory neurons results only in non-dauer offspring that develop into males or females. High population densities correlate with changes in the methylation status of H3K4 and H3K9 in the maternal germline. Inhibition of JMJD histone demethylases prevents mothers from producing dauers and hermaphrodite offspring in high-density conditions. Our results demonstrate a case of soma-to-germline transmission of environmental information that influences the phenotype of the following generation through changes in histone modifications of the maternal germline.\n\nHighlightsO_LIHigh population density leads to the production of hermaphrodite offspring.\nC_LIO_LIThe ASH neuron in the hermaphrodite mother senses population density.\nC_LIO_LIHistone modifications in the maternal germline correlate with the sex of offspring.\nC_LIO_LIInhibition of histone demethylases results in female offspring in all conditions.\nC_LI

developmental biology↗

bioRxiv2017

Gender- and gamete-specific patterns of X chromosome segregation in a three-gendered nematode

Meiosis is at the core of sexual reproduction and alterations to its program can have dramatic effects. In this study, we investigate the segregation pattern of the X chromosome in Auanema rhodensis, a three-gendered nematode. This species has an atypical pattern of X chromosome segregation during male spermatogenesis that results in the exclusive production of haplo-X sperm. Here we use a combination of genetic and cytological approaches to show that while XX females undergo conventional meiosis to produce mostly haplo-X oocytes, hermaphrodites undergo atypical meiosis to produce nullo-X oocytes and mostly diplo-X sperm. Gender- and gamete-specific alterations of the normal meiotic program include non-pairing of the X homologs and precocious separation of X chromatids. Given these intra-species, intra-individual and intra-gametogenesis variations in meiotic program of A. rhodensis, we argue that it is an ideal model to study the plasticity of meiosis and how it can be modulated.\n\nHighlights- Matings between A. rhodensis hermaphrodites and males generate only male crossprogeny.\n- Hermaphrodites generate mostly nullo-X oocytes and diplo-X sperm.\n- Following normal Mendelian genetics, XX females produce haplo-X oocytes.\n- In cross-progeny, sons always inherit the X chromosome from the father.

genetics↗