Browsing by Author "Matos, Ricardo"
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- NineTeen Complex-subunit Salsa is required for efficient splicing of a subset of introns and dorsal-ventral patterningPublication . Rathore, Om; Silva, Rui D.; Ascensao-Ferreira, Mariana; Matos, Ricardo; Carvalho, Celia; Marques, Bruno; Tiago, Margarida N.; Prudencio, Pedro; Andrade, Raquel P.; Roignant, Jean-Yves; Barbosa-Morais, Nuno; Martinho, Rui GoncaloThe NineTeen Complex (NTC), also known as pre-mRNA-processing factor 19 (Prp19) complex, regulates distinct spliceosome conformational changes necessary for splicing. During Drosophila midblastula transition, splicing is particularly sensitive to mutations in NTC-subunit Fandango, which suggests differential requirements of NTC during development. We show that NTC-subunit Salsa, the Drosophila ortholog of human RNA helicase Aquarius, is rate-limiting for splicing of a subset of small first introns during oogenesis, including the first intron of gurken. Germline depletion of Salsa and splice site mutations within gurken first intron impair both adult female fertility and oocyte dorsal-ventral patterning, due to an abnormal expression of Gurken. Supporting causality, the fertility and dorsal-ventral patterning defects observed after Salsa depletion could be suppressed by the expression of a gurken construct without its first intron. Altogether, our results suggest that one of the key rate-limiting functions of Salsa during oogenesis is to ensure the correct expression and efficient splicing of the first intron of gurken mRNA. Retention of gurken first intron compromises the function of this gene most likely because it undermines the correct structure and function of the transcript 5'UTR.
- Regulation of gene expression during Drosophila oocyte developmentPublication . Matos, Ricardo; Martinho, Rui Gonçalo; Silva, RuiHuman oocytes can stay dormant for several decades in meiotic arrest, before reactivation and maturation. Similar, Drosophila oocyte is mostly transcriptionally quiescent during prophase I-arrest, transiently reactivating gene expression just before it progresses into metaphase I. Our aim is to better understand such reactivation and its role for oocyte maturation and female fertility. This work is divided in 3 chapters. In chapter I we use an isolated loss of function allele of dkdm5 to characterize the function of this enzyme during oogenesis. The results obtained with the loss of function allele of dkdm5 are consistent, albeit stronger, with the phenotypes previously observed after RNAi depletion and hypomorphic allele of dkdm5. Yet, a qualitatively distinct phenotype has also been identified, suggesting a new function of dkdm5 during oocyte maturation. In chapter II we try to access chromatin quality and synaptonemal complex assembly throughout oocyte development. Proteins from chromatin remodelling complexes, as dkdm5, have been shown to disrupt the synaptonemal complex further leading to problems in meiotic progression. Here we observed that two core components of the pho repressive complex are required for female fertility. Further, we show that specific germline dSfmbt depletion leads to an abnormal increase of Corolla and defective synaptonemal complex morphology in the oocyte chromatin throughout development. Chapter III is an independent chapter where we reveal Nine Teen Complex Protein Salsa as being particularly rate limiting for efficient splicing of short proximal introns and dorsoventral patterning of the Drosophila egg. We observed that, upon specific germline depletion of Salsa, Gurken transcript is poorly spliced leading to an abnormal localization, subsequentially leading to defects in the eggshell dorsoventral patterning and female fertility. Further we show that ectopic Gurken expression can suppress the dorsal ventral patterning defects after Salsa depletion. Our work aims to mechanistically understand our observations.
- Sound production by the Lusitanian toadfish, Halobatrachus didactylusPublication . Santos, Manuel Eduardo dos; Modesto, Teresa; Matos, Ricardo; Grober, M. S.; Oliveira, R. F.; Canario, Adelino V. M.Several batrachoidids have been known to produce sounds associated with courtship and agonistic interactions, and their repertoires have been studied acoustically and behaviourally. In contrast, sound production of the Lusitanian toadish Halobatrachus didactylus, although often noted, has not been acoustically studied. This sedentary predator of Northeastern Atlantic coastal waters is usually found in sandy and muddy substrates, under rocks or crevices. Sound recordings were made in Ria Formosa, a lagoon complex in southern Portugal. The sound producing apparatus was studied in adult individuals of both sexes captured by local fishermen. It is shown that this species produces acoustic emissions similar to other batrachoidids. It produces a long, rhythmical, tonal sound, often in choruses, which is comparable to the boatwhistle or hum signals of Opsanus and Porichthys, and a complex of signals that were classified as grunts, croaks, double croaks and mixed calls ('grunt-croak’). As in other toadfishes, H. didactylus presents sonic muscles connected to a bi-lobed swimbladder. Asynchronous contractions of the sonic muscles were detected when massaging the ventral surface of the fish.