Sex-Chromosome Homomorphy in Palearctic Tree Frogs Results from Both Turnovers and X-Y Recombination.

Contrasting with birds and mammals, poikilothermic vertebrates often have homomorphic sex chromosomes, possibly resulting from high rates of sex-chromosome turnovers and/or occasional X-Y recombination. Strong support for the latter mechanism was provided by four species of European tree frogs, which inherited from a common ancestor (∼ 5 Ma) the same pair of homomorphic sex chromosomes (linkage group 1, LG1), harboring the candidate sex-determining gene Dmrt1. Here, we test sex linkage of LG1 across six additional species of the Eurasian Hyla radiation with divergence times ranging from 6 to 40 Ma. LG1 turns out to be sex linked in six of nine resolved cases. Mapping the patterns of sex linkage to the Hyla phylogeny reveals several transitions in sex-determination systems within the last 10 My, including one switch in heterogamety. Phylogenetic trees of DNA sequences along LG1 are consistent with occasional X-Y recombination in all species where LG1 is sex linked. These patterns argue against one of the main potential causes for turnovers, namely the accumulation of deleterious mutations on nonrecombining chromosomes. Sibship analyses show that LG1 recombination is strongly reduced in males from most species investigated, including some in which it is autosomal. Intrinsically low male recombination might facilitate the evolution of male heterogamety, and the presence of important genes from the sex-determination cascade might predispose LG1 to become a sex chromosome.

Ever-young sex chromosomes in European tree frogs.

Non-recombining sex chromosomes are expected to undergo evolutionary decay, ending up genetically degenerated, as has happened in birds and mammals. Why are then sex chromosomes so often homomorphic in cold-blooded vertebrates? One possible explanation is a high rate of turnover events, replacing master sex-determining genes by new ones on other chromosomes. An alternative is that X-Y similarity is maintained by occasional recombination events, occurring in sex-reversed XY females. Based on mitochondrial and nuclear gene sequences, we estimated the divergence times between European tree frogs (Hyla arborea, H. intermedia, and H. molleri) to the upper Miocene, about 5.4-7.1 million years ago. Sibship analyses of microsatellite polymorphisms revealed that all three species have the same pair of sex chromosomes, with complete absence of X-Y recombination in males. Despite this, sequences of sex-linked loci show no divergence between the X and Y chromosomes. In the phylogeny, the X and Y alleles cluster according to species, not in groups of gametologs. We conclude that sex-chromosome homomorphy in these tree frogs does not result from a recent turnover but is maintained over evolutionary timescales by occasional X-Y recombination. Seemingly young sex chromosomes may thus carry old-established sex-determining genes, a result at odds with the view that sex chromosomes necessarily decay until they are replaced. This raises intriguing perspectives regarding the evolutionary dynamics of sexually antagonistic genes and the mechanisms that control X-Y recombination.

[Kinesiotherapy prevents shoulder pain in hemiplegic/paretic patients on sub-acute stage post-stroke]. / Cinesioterapia previne ombro doloroso em pacientes hemiplégicos/paréticos na fase sub-aguda do acidente vascular encefálico.

BACKGROUND: Painful shoulder is considered the most common complication of hemiplegic/parethic (H/P) stroke patients. It is a negative factor for neuromotor recovery. PURPOSE: To study the effects of kinesiotherapy treatment on shoulder pain prevention, and as a secondary endpoints, to analyze muscle strength of H/P shoulder looking at basic functional active mobility. METHOD: Twenty one inpatients (12 men, 9 women) aged 26 to 87 years, with post-stroke H/P were submitted to thirty minutes daily program kinesiotherapy, started at 48 hours post-stroke up to their hospital discharge. Patients were evaluated pre and post treatment according to the presence or absence of shoulder pain, movements and shoulder strength, and for presence or absence of basic functional movements. RESULTS: No patient complaining of shoulder pain at the hospital discharge (p<0.001). The muscle strength improved signifcantly for elevation, protusion, abduction and flexion of the shoulder (p<0.001). There was improvement also for functional mobility on moving from dorsal to lateral recumb, from lateral recumb to a seated position and in keeping the seated position (p<0.001). CONCLUSION: Kinesiotherapy in acute phase of stroke prevented shoulder pain.

Chromosomal rearrangements do not seem to affect the gene flow in hybrid zones between karyotypic races of the common shrew (Sorex araneus).

Chromosomal rearrangements are proposed to promote genetic differentiation between chromosomally differentiated taxa and therefore promote speciation. Due to their remarkable karyotypic polymorphism, the shrews of the Sorex araneus group were used to investigate the impact of chromosomal rearrangements on gene flow. Five intraspecific chromosomal hybrid zones characterized by different levels of karyotypic complexity were studied using 16 microsatellites markers. We observed low levels of genetic differentiation even in the hybrid zones with the highest karyotypic complexity. No evidence of restricted gene flow between differently rearranged chromosomes was observed. Contrary to what was observed at the interspecific level, the effect of chromosomal rearrangements on gene flow was undetectable within the S. araneus species.

Cinesioterapia previne ombro doloroso em pacientes hemiplégicos/paréticos na fase sub-aguda do acidente vascular encefálico / Kinesiotherapy prevents shoulder pain in hemiplegic/paretic patients on sub-acute stage post-stroke

CONTEXTO: Ombro doloroso é freqüente em pacientes com hemiplegia/hemiparesia (H/P) por acidente vascular encefálico (AVE), dificultando a recuperaçäo neuromotora gerando incapacidade funcional. OBJETIVO: Estudar tratamento fisioterapêutico para a prevençäo da dor no ombro com H/P em pacientes com AVE na fase sub-aguda, e analisar desfechos secundários (força muscular do ombro acometido e movimentos funcionais ativos básicos). MÉTODO: Estudaram-se 21 pacientes (12 homens, 9 mulheres; idades 26 a 87 anos) com H/P. O tratamento fisioterapêutico consistiu de 30 minutos diários de cinesioterapia, desde as 48 horas após o AVE até a alta hospitalar. Os pacientes foram avaliados antes e após o tratamento em relaçäo à presença ou ausência de dor no ombro H/P, à força dos diversos grupos musculares do ombro e quanto aos movimentos funcionais de transferência e manutençäo postural básica. RESULTADOS: Nenhum paciente apresentava dor no ombro H/P na alta (p<0,001). A força muscular aumentou significativamente em relaçäo à elevaçäo, protusäo, abduçäo e flexäo do ombro (p<0,001). Houve melhora dos movimentos funcionais: decúbito dorsal para lateral, decúbito lateral para sentado e manter-se sentado (p<0,001). CONCLUSÄO: A cinesioterapia na fase aguda do AVE preveniu a dor no ombro H/P e favoreceu a recuperaçäo motora