[Show abstract][Hide abstract] ABSTRACT: Evolution of sex determination and differentiation in fishes involves a broad range of sex strategies (hermaphroditism, gonochorism, unisexuality, environmental and genetic sex determination). Annual fishes inhabit temporary ponds that dry out during the dry season when adults die. The embryos exhibit an atypical developmental pattern and remain buried in the bottom mud until the next rainy season. To elucidate genomic factors involved in the sex determination in annual fish, we explored the presence of a candidate sex-specific gene related to the cascade network in Austrolebias charrua. All phylogenetic analyses showed a high posterior probability of occurrence for a clade integrated by nuclear sequences (aprox. 900 bp) from both adults (male and female), with partial cDNA fragments of A. charrua from juveniles (male) and the dsx D. melanogaster gene. The expressed fragment was detected from blastula to adulthood stages showing a sexually dimorphic expression pattern. The isolated cDNA sequence is clearly related to dsx D. melanogaster gene and might be located near the top of the sex determination cascade in this species.
Full-text · Article · Jun 2014 · Genetics and Molecular Biology
[Show abstract][Hide abstract] ABSTRACT: Annual fishes are found in both Africa and South America occupying ephemeral ponds that dried seasonally.
Neotropical annual fishes are members of the family Rivulidae that consist of both annual and non-annual fishes.
Annual species are characterized by a prolonged embryonic development and a relatively short adult life.
Males and females show striking sexual dimorphisms, complex courtship, and mating behaviors. The prolonged
embryonic stage has several traits including embryos that are resistant to desiccation and undergo up to three
reversible developmental arrests until hatching. These unique developmental adaptations are closely related to the
annual fish life cycle and are the key to the survival of the species.
Most of the available data on Neotropical annual fishes derive from studies on the genus Austrolebias. Herein, we
review and summarize the available data on the evolution, reproduction strategy, developmental biology and
conservation status of these Neotropical fishes.
Full-text · Article · May 2014 · Seminars in Cell and Developmental Biology
[Show abstract][Hide abstract] ABSTRACT: Annual fish are freshwater teleosts found in South America and Africa that are exposed to an extremely variable environment. They develop and reproduce in seasonal ponds that dry during the summer eliminating the entire adult population. Remarkably, desiccation-resistant embryos survive in these dry ponds that hatch during the next rainy season when the ponds are recreated. Among vertebrates, they represent one of the most remarkable extremophiles. They share several features with other fish models; however, they exhibit unique traits related to their peculiar life cycle. Epiboly is temporally and spatially uncoupled from organogenesis, and the embryos can undergo reversible developmental arrests (diapauses). These attributes make them a useful model to study diverse topics in developmental biology using a comparative and evolutionary approach. In this article, different aspects related to annual fish biology, taxonomy and phylogenetic considerations, reproductive strategy, and developmental characteristics with special focus on arrests, are summarized. The current challenge is to document and determine the factors that generate such high diversity and unique adaptations of annual fish. To understand this complexity, interdisciplinary approaches are being employed taking into consideration evolutionary biology, ethology, reproductive strategies, regulation of developmental mechanisms, and senescence. WIREs Dev Biol 2012, 1:595-602. doi: 10.1002/wdev.39 For further resources related to this article, please visit the WIREs website.
[Show abstract][Hide abstract] ABSTRACT: The current knowledge about teleost fish egg envelope is summarized. The paper analyzes the organization and deposition process of the protein composition and genes involved in the synthesis of teleost fish egg envelopes and their role in gamete interaction during fertilization. Pelagic and demersal species that our research group is working with are especially considered. The vertebrate ZP family of proteins, the evolution and relationship among the different genes and their expression are taken into account. We consider fish envelope as a possible biomonitor for ecological contaminants. The biotechnological applications for aquaculture and genomic and post-genomic approaches are auspicious.
Full-text · Article · Jan 2011 · Biological research
[Show abstract][Hide abstract] ABSTRACT: Sex differentiation process, determination of sexual strategy, and gametogenesis of the annual fish Austrolebias charrua are established. Evidence of histological sex differentiation in an antero-posterior gradient was observed in pre-hatching stages. Sexual strategy corresponds to the "differentiated gonochoric" pattern. Histological analyses of adult gonads showed an asynchronous spawning mode for females and continuous spawning for males. Mature oocytes presented fluid yolk. Testis organization corresponded to a restricted spermatogonial model. Herein, we report the ultrastructural organization of the vitelline envelope and the main features of the sperm of A. charrua. Taking together these results also contribute to phylogenetic studies and provide base line data to propose A. charrua as a biomonitor of contamination in a protected area.
[Show abstract][Hide abstract] ABSTRACT: Hox genes encode a family of transcription factors implicated in conferring regional identity along the anteroposterior axis in developing animal embryos. These genes are organized in genomic clusters, expressed collinearly and highly conserved in vertebrates. Among teleost, South American annual killifishes of the Cynolebiatinae subfamily represent an excellent model in development studies because their embryos are capable of undergoing reversible developmental arrest (diapause) at three well-defined morphological stages. They are also an excellent model for evolutionary studies due to the high rates of mutation of their mitochondrial genome, their karyotypic divergence and their morphological variability. In this study, three partial homeobox sequences were isolated from different species of the Cynolebiatinae subfamily. Phylogenetic analyses and sequence comparisons revealed that they belong to the anterior Hox complex group, specifically to paralogue groups 1 and 3. This is the first time that partial Hox genes have been described in species of the Cynolebiatinae subfamily.
Full-text · Article · Mar 2007 · Genetics and Molecular Biology
[Show abstract][Hide abstract] ABSTRACT: The organization, time-course deposition and protein composition of the oocyte envelope in the whitemouth croaker, Micropogonias furnieri, were analyzed at different stages of oocyte maturation. Adult females were sampled in the Uruguayan coast of the Río de la Plata during three annual periods. Morphological organization and temporal deposition were assessed by histology and electron microscopy. Protein composition was analyzed using gel electrophoresis, followed by MALDI-TOF-MS. Oocyte envelope deposition starts in lipid-yolk oocytes, reaching maximum width in fully grown oocytes when it shows a three-layer organization. In mature oocytes, the envelope becomes narrower than in the previous stage and loses its trilaminar structure. In envelopes from fully grown oocytes, one-dimensional gel electrophoresis revealed five bands; mature oocytes showed only three bands. Following two-dimensional gel electrophoresis, 14 major polypeptides were detected in envelopes from fully grown oocytes. Considering that morphological and biochemical results obtained from samples of the three annual periods were remarkably similar, data reported here might provide a useful baseline to assess the future impact of pollutants on the oocyte envelope and reproductive success of whitemouth croakers inhabiting the geographic area.
No preview · Article · Jan 2007 · Journal of Applied Ichthyology
[Show abstract][Hide abstract] ABSTRACT: The detailed characteristics and timing of early development in Cynolebias viarius, an annual fish endemic to Uruguay, were obtained from in vivo observations of embryos cultured under standardized laboratory conditions. The chorion ultrastructure is reported for this species for the first time. Comparison with previous data from other annual fishes showed that C. viarius exhibited the longest early development including cleavage, blastula formation and epiboly. (c) 2005 The Fisheries Society of the British Isles.
No preview · Article · May 2005 · Journal of Fish Biology
[Show abstract][Hide abstract] ABSTRACT: The detailed characteristics and timing of early development in Cynolebias viarius, an annual fish endemic to Uruguay, were obtained from in vivo observations of embryos cultured under standardized laboratory conditions. The chorion ultrastructure is reported for this species for the first time. Comparison with previous data from other annual fishes showed that C. viarius exhibited the longest early development including cleavage, blastula formation and epiboly.
Preview · Article · Apr 2005 · Journal of Fish Biology