Morphology of yolk and pericardial sacs in lecithotrophic and matrotrophic nutrition in poeciliid fishes.

We used histological techniques to describe the morphology of the yolk and pericardial sacs in developing embryos of the lecithotrophic species Girardinus creolus, Gambusia puncticulata, Limia vittata, and Quintana atrizona, in comparison with the extreme matrotrophic Heterandria formosa. In lecithotrophic species, the yolk sac was enlarged and lasted until the final stages of development, while in H. formosa it was completely absorbed soon after fertilization. Lecithotrophic poeciliids showed a pericardial sac with a single layer of blood vessels covering the dorsal surface of the cephalic region only, while H. formosa showed a more complex largely vascularized pericardial sac covering the entire dorsal surface, except the caudal region. In advanced gestation of G. creolus, a vascular plexus of the yolk sac reaches the pharyngeal region, behind the gills, suggesting that the pharynx may play a role in embryonic nutrition in lecithotrophic species. These morphological evidences suggest that matrotrophy derives from lecithotrophy.

Phylogeography of Cuban Rivulus: evidence for allopatric speciation and secondary dispersal across a marine barrier.

The genus Rivulus is currently comprised of two species, R. cylindraceus and R. insulaepinorum, which are endemic to Cuba. However, the taxonomic status of the latter species remains dubious because of the poor quality of the original description. In addition, a recent barcoding survey suggests that the two species may be conspecific. The aim of this study was to test the hypothesis that the two species represent a single evolutionary clade. To delimit the species and their evolutionary history, we used a combination of molecular phylogenetic analyses, with both mitochondrial and nuclear sequences, tests of phylogeographic hypotheses, combined with morphological measurements and information on known dispersal barriers and species distribution. None of the data sets support R. insulaepinorum and R. cylindraceus as separate taxa. However, a new species, restricted to the northwestern part of the main island, was identified by phylogenetic analyses, body colour pattern and geographical distribution. The evolutionary distance between the two lineages (cytb, d=15%; CAM-4, d=2.5%) indicates a long period of divergence. Phylogeographic analyses shed light on the dispersal history of R. cylindraceus, which probably originated on the Isla de la Juventud. They also suggest that each lineage had contrasting histories; Rivulus sp. is restricted to a relatively small geographic area whereas R. cylindraceus has dispersed considerably and more than once from its centre of origin, probably facilitated by sea level fluctuations. These results strengthen previous findings, i.e. that the diversity of Cuban freshwater fishes is far from well-known and deserves more in-depth studies, and that vicariance and dispersal events have resulted in a complex biogeographical landscape which has had a significant impact on the freshwater fishes of the Caribbean islands.

DNA barcoding of Cuban freshwater fishes: evidence for cryptic species and taxonomic conflicts.

Despite ongoing efforts to protect species and ecosystems in Cuba, habitat degradation, overuse and introduction of alien species have posed serious challenges to native freshwater fish species. In spite of the accumulated knowledge on the systematics of this freshwater ichthyofauna, recent results suggested that we are far from having a complete picture of the Cuban freshwater fish diversity. It is estimated that 40% of freshwater Cuban fish are endemic; however, this number may be even higher. Partial sequences (652 bp) of the mitochondrial gene COI (cytochrome c oxidase subunit I) were used to barcode 126 individuals, representing 27 taxonomically recognized species in 17 genera and 10 families. Analysis was based on Kimura 2-parameter genetic distances, and for four genera a character-based analysis (population aggregation analysis) was also used. The mean conspecific, congeneric and confamiliar genetic distances were 0.6%, 9.1% and 20.2% respectively. Molecular species identification was in concordance with current taxonomical classification in 96.4% of cases, and based on the neighbour-joining trees, in all but one instance, members of a given genera clustered within the same clade. Within the genus Gambusia, genetic divergence analysis suggests that there may be at least four cryptic species. In contrast, low genetic divergence and a lack of diagnostic sites suggest that Rivulus insulaepinorum may be conspecific with Rivulus cylindraceus. Distance and character-based analysis were completely concordant, suggesting that they complement species identification. Overall, the results evidenced the usefulness of the DNA barcodes for cataloguing Cuban freshwater fish species and for identifying those groups that deserve further taxonomic attention.

Limitación de los movimientos articulares en diabéticos. Informe preliminar. / Limitation of articulatory movements in diabetic patients. Preliminary report

Se estudiaron 106 pacientes diabéticos insulinodependientes de la consulta de diabetes infantil y del adolescente del Instituto Nacional de Endocrinología. Se determinó la presencia de limitación de los movimientos articulares de la mano (LMA) en todos ellos, y se relacionó con la edad, el tiempode evolución de la diabetes, el control metabólico, el peso, la talla y la presencia de retinopatía. Se encontró que 73 (68

) de los pacientes estaban afectados con LMA. La edad promedio de todos los grupos fue similar (16,8 sin LMA, 15,9 y 17,8 para grados I y II de LMA). Los más afectados tuvieron más años de evolución de la diabetes que los no afectados (11,7 vs 4,4; respectivamente) con una diferencia significativa de p < 0,005. Igualmente el grupo de afectados tuvo un porcentaje más elevado de HbA1C (11,8 vs 10,1) para una significación de p < 0,001. Se encontró, además, que los que presentaban LMA tuvieron un porcentaje significativamente mayor (p < 0,001) de pacientes por debajo de 50 percentil para el peso y la talla. La retinopatía también estuvo presente en un porcentaje mayor (45

) en los afectado que en los restantes (13

), para una significación de p<0,01. Se valora la posibilidad de que estos pacientes tengan características genéticas específicas y se sugiere que se realicen determinaciones de HLA para poder caracterizar mejor a estos pacientes. (AU)