Phylogeny,genetic diversity and phylogeography of the genus Codoma (Teleostei,Cyprinidae)

This study represents a thorough analysis of Codoma, a monotypic genus endemic to north‐western Mexico. A previous morphological analysis of the species concluded that there exists several morphological groups in Codoma ornata, suggesting diversity in Codoma could be underestimated. No studies have examined the genetic diversity in Codoma ornata to test this hypothesis and identify independent lineages. We present a phylogeographic analysis using one mitochondrial and two nuclear genes, and specimens from across nine major drainages in both the Chihuahuan Desert and the Sierra Madre Occidental of western Mexico. All genes and analyses recovered populations of Codoma in a well‐supported clade and sister to Tampichthys, and this clade sister to Cyprinella. Analyses of both mitochondrial and nuclear genes indicated Codoma is not monotypic and recover more diversity in the genus than currently recognized. The four (mitochondrial) and five (nuclear) genetically distinct lineages are consistent with those groups outlined in the prior morphological study of the genus. Composition and distribution of these major lineages is also consistent with prior biogeographic hypothesis for other fishes in the region, supporting an ancestral Rio Grande system extending south towards central Mexico. Fragmentation of this paleosystem was followed by allopatric speciation in the Chihuahuan Desert. These results suggest a scenario of long‐term isolation in four major regions (upper Conchos, lower Conchos, Nazas, upper Mezquital). Resolution of the diversity and biogeography of these lineages has many implications for various biological disciplines, especially for evolutionary and conservation studies.     

In memoriam: Costas Drainas (1950-2011)

This is a short recollection of C. Drainas research and memoirs on occasion of his untimely death.     

Maternal bereavement: The heightened mortality of mothers after the death of a child

Using a 9-year follow-up of 69,224 mothers aged 20–50 from the National Longitudinal Mortality Survey, we investigate whether there is heightened mortality of mothers after the death of a child. Results from Cox proportional hazard models indicate that the death of a child produces a statistically significant hazard ratio of 2.3. There is suggestive evidence that the heightened mortality is concentrated in the first two years after the death of a child. We find no difference in results based on mother's education or marital status, family size, the child's cause of death or the gender of the child.     

Isolation of mastocytes from rat peritoneal fluid using continuous Ficoll gradients

A method for mast cells purification from rat peritoneal fluid is described. The method consists of a continuous Ficoll gradient between 20 and 22,5% (w/v) Ficoll and the cells are obtained with an 88% retrieval. Purity and viability were of 95% and 97% respectively. The cells so purified were functional against the compound 48/80 and the spontaneous secretion value was less than 8%.