RESUMEN
Surubim (Pseudoplatystoma corruscans, Pimelodidae) are migratory catfish native to the rivers in the La Plata and São Francisco basins. They are piscivores that attain considerable body sizes and are a valuable economic resource. Surubim exhibits extensive migrations during its life cycle that may affect the population structure at vast geographic scales. The authors examined the genetic diversity and population genetic structure of P. corruscans using microsatellite markers from a comprehensive sampling of 260 individuals from the Upper and Lower Paraná River. They identified two well-differentiated genetic clusters corresponding to a natural geographic barrier historically separating Upper and Lower Paraná regions. They also demonstrated temporal variation in population genetic structure at a site in Lower Paraná close to the confluence with the Paraguay River, most likely explained by the influx of migrant fishes at certain times of the year.
Asunto(s)
Bagres , Animales , Bagres/genética , Genética de Población , Ríos , Brasil , Repeticiones de Microsatélite , Variación GenéticaRESUMEN
Population genetics studies the distributions and changes in population allele frequencies in response to processes, such as mutation, natural selection, gene flow, and genetic drift. Researchers daily manage genetic, biological, and environmental data of the samples, storing them in text files or spreadsheets, which makes it difficult to maintain consistency and traceability. Here we present TEGA, a WEB-based stand-alone software developed for the easy analysis and management of population genetics data. It was designed to: 1) facilitate data management, 2) provide a way to execute the analysis procedures, and 3) supply a means to publish data, procedures, and results. TEGA is distributed under the GNU AGPL v3 license. The documentation, source code, and screenshots are available at https://github.com/darioelias/TEGA. In addition, we present Rabid Fish, the first implementation of TEGA in the Genetics Labortory of the Faculty of Humanities and Sciences at the National University of the Litoral, where research focuses on population genetics studies applied to non-model organisms.
RESUMEN
Ceratium furcoides is an invasive freshwater dinoflagellate that in the last three decades has expanded its geographic distribution in South America, being recently found in Paraná River floodplain (Argentina). Despite growing concern about the presence and impacts of this invader, information regarding genetic diversity in the Southern Hemisphere is missing. This work constitutes the first phylogenetic characterization of Ceratium populations of South America, particularly, from the Paraná system. After taxonomic identification as C. furcoides based on morphological traits, two sequencing-based approaches were applied using the ribosomal 18S gene: Sanger sequencing to isolated individuals and high-throughput amplicon sequencing (HTS) to environmental DNA. The sequence of C. furcoides obtained shared 100% identity to Asian sequences, and formed a highly supported clade in the constructed reference phylogenetic tree. HTS helped to recover low-frequency genetic variants suggesting the presence of different population of C. furcoides, and to alert potential invasion in its early stages.
Asunto(s)
Dinoflagelados , Argentina , Dinoflagelados/genética , Agua Dulce , Filogenia , Análisis de Secuencia de ADN , América del SurRESUMEN
The yacare caiman (Caiman yacare) is a reptile from South America and 1 of the 2 crocodilian species present in Argentina. The degradation of their natural habitat and strong hunting pressure led to a sharp numerical decline of wild populations. Nowadays, C. yacare is included in Appendix II of CITES, and ranching practices in some areas in Argentina are helping hatching success. In this context, it is important to better understand the population structure and mating system of the species. To do this, we amplified 10 microsatellite markers (SSRs) in 148 individuals of 13 C. yacare nests. All of the markers were polymorphic with 212 alleles per locus, with allelic sizes ranging between 154 and 400 bp and medium levels of polymorphism (Ho = 0.1520.551 and He = 0.2210.621). We were able to determine the maternal genotype in 9 out of 13 nests. In 6 of them we found more than 1 paternal genotype, with a maximum of 3 fathers for a single nest. This study is the first to provide evidence of multiple paternity behavior. These findings will be useful to improve management and conservation strategies for the species.
Asunto(s)
Caimanes y Cocodrilos/genética , Genética de Población , Repeticiones de Microsatélite , Alelos , Animales , Argentina , Femenino , Marcadores Genéticos , Genotipo , Masculino , Reproducción , Conducta Sexual AnimalRESUMEN
Prochilodus lineatus is a highly migratory fish species that sustains the most important commercial fishery of Paraná-Paraguay basin. Migratory patterns are poorly known and only few population genetic studies are available for this species in the Upper Paraná. To assess genetic population structure, we genotyped a sample of 93 individuals from the Lower Uruguay River close to Gualeguaychú city (Entre Ríos, Argentina) at three different times, July 2008 (Winter), September 2008 (Spring) and May 2009 (Fall). All individuals were genotyped for 12 microsatellite loci previously found to be informative to assess populations of P. lineatus. Our results show seasonal variation of the genetic sub-structuring at this locality that may be related to the presence of different migratory stocks throughout the year. The Fall sample includes an additional genetic cluster of individuals not detected in Winter and Spring, suggesting that this species should be considered a mixed stock fishery.
Asunto(s)
Characiformes/genética , Variación Genética , Estaciones del Año , Migración Animal , Animales , Genotipo , Repeticiones de Microsatélite , Población/genéticaRESUMEN
Homeodomain-leucine zipper proteins constitute a family of transcription factors found only in plants. Expression patterns of the sunflower homeobox-leucine zipper gene Hahb-10 (Helianthus annuus homeobox-10), that belongs to the HD-Zip II subfamily, were analysed. Northern blots showed that Hahb-10 is expressed primarily in mature leaves, although expression is clearly detectable in younger leaves and also in stems. Considerably higher expression levels were detected in etiolated seedlings compared with light-grown seedlings. Induction of Hahb-10 expression was observed when seedlings were subjected to treatment with gibberellins. Transgenic Arabidopsis thaliana plants that express Hahb-10 under the 35S cauliflower mosaic virus promoter show special phenotypic characteristics such as darker cotyledons and planar leaves. A reduction in the life cycle of about 25% allowing earlier seed collection was also observed, and this phenomenon is clearly related to a shortened flowering time. When the number of plants per pot increased, the difference in developmental rate between transgenic and non-transformed individuals became larger. After gibberellin treatment, the relative difference in life cycle duration was considerably reduced. Several light-regulated genes have been tested as possible target genes of Hahb-10. One of them, PsbS, shows a different response to illumination conditions in transgenic plants compared with the response in wild-type plants while the other genes behave similarly in both genotypes. We propose that Hahb-10 functions in a signalling cascade(s) that control(s) plant responses to light quality and quantity, and may also be involved in gibberellin transduction pathways.