Nosema ceranae in South American Native Stingless Bees and Social Wasp.

Besides the incipient research effort, the role of parasites as drivers of the reduction affecting pollinator populations is mostly unknown. Given the worldwide extension of the beekeeping practice and the diversity of pathogens affecting Apis mellifera populations, honey bee colonies are a certain source of parasite dispersion to other species. Here, we communicate the detection of the microsporidium Nosema ceranae, a relatively new parasite of honey bees, in stingless bees (Meliponini) and the social wasp Polybia scutellaris (Vespidae) samples from Argentina and Brazil by means of duplex PCR. Beyond the geographic location of the nests, N. ceranae was detected in seven from the eight Meliponini species analyzed, while Nosema apis, another common parasite of A. mellifera, was absent in all samples tested. Further research is necessary to determine if the presence of the parasite is also associated with established infection in host tissues. The obtained information enriches the current knowledge about pathologies that can infect or, at least, be vectored by native wild pollinators from South America.

Male cytogenetic evaluation prior to assisted reproduction procedures performed in Mar del Plata, Argentina.

OBJECTIVE: This paper aimed to estimate the frequency of occurrence and the types of chromosomal abnormalities found in 141 infertile men with abnormal semen parameters. METHODS: the frequency and type of chromosomal abnormalities were determined with male mitotic karyotype analysis from peripheral blood through chromosome banding techniques before assisted reproduction procedures. RESULTS: In this series of 141 infertile men, 19 (13%) had chromosomal anomalies and 35 (25%) had polymorphic variants. The main chromosome abnormalities were reciprocal translocations and marker chromosomes in mosaic. CONCLUSIONS: These results stress the relevance of cytogenetic studies for infertile males as a diagnostic tool and a valuable input in genetic counseling.

Genetics and geometry of canalization and developmental stability in Drosophila subobscura.

BACKGROUND: Many properties of organisms show great robustness against genetic and environmental perturbations. The terms canalization and developmental stability were originally proposed to describe the ability of an organism to resist perturbations and to produce a predictable target phenotype regardless of random developmental noise. However, the extent to which canalization and developmental stability are controlled by the same set of genes and share underlying regulatory mechanisms is largely unresolved. RESULTS: We have analyzed the effects of clinical genetic variation (inversion polymorphism) on wing asymmetry by applying the methods of geometric morphometrics in the context of quantitative genetics using isochromosomal lines of Drosophila subobscura. For the analysis of overall size, developmental stability was positively correlated with levels of heterozygosity and development at the optimal temperature. For analyses of shape, the overall comparisons by matrix correlations indicate that inter- and intraindividual variation levels were poorly correlated, a result also supported when comparing the vectors describing patterns of variation of landmark position. The lack of similarity was basically due to the discrepancy between the genetic and environmental components of the interindividual variation. Finally, the analyses have also underscored the presence of genetic variation for directional asymmetry. CONCLUSIONS: The results strongly support the hypothesis that environmental canalization and developmental stability share underlying regulatory mechanisms, but environmental and genetic canalization are not functionally the same. A likely explanation for this lack of association is that natural wing shape variation in Drosophila populations is loosely related to individual fitness.

New Sequence Variations in Spermatogenesis Candidates Genes.

OBJECTIVE: The aim of this paper was to estimate the frequency and types of mutations in key candidate genes involved in spermatogenesis, and their potential role as a cause of azoospermia /cryptozoospermia. METHODS: The sequencing of the coding region of genes DBY, RBMY, DAZ, CDY and BPY2, excluding the promoter region, was performed in a series of 25 patients with azoospermia or severe oligozoospermia without AZF microdeletions. The exon 3 from the DAZL gene (DAL3) was also sequenced. The sequences obtained were analyzed by ProSeq, DnaSP v5 and compared with the database using Blastn and tblastx. RESULTS: 16 of the 25 patients showed some type of variants, such as transversions, transitions, deletions and/or insertions in the DAZ, DAZL, CDY and RBMY genes. The mutated sequences had between 97 and 99% homology with the specific protein of every gene, except the DAZL (73%) and DAZ (94%) proteins. CONCLUSION: The variants found have not been described previously, suggesting they could be mutations that might affect protein function.

Quantitative-genetic analysis of wing form and bilateral asymmetry in isochromosomal lines of Drosophila subobscura using Procrustes methods.

Fluctuating asymmetry (FA) is often used as a measure of underlying developmental instability (DI), motivated by the idea that morphological variance is maladaptive. Whether or not DI has evolutionary potential is a highly disputed topic, marred by methodological problems and fuzzy prejudices. We report here some results from an ongoing study of the effects of karyotype, homozygosity and temperature on wing form and bilateral asymmetry using isochromosomal lines of Drosophila subobscura. Our approach uses the recently developed methodologies in geometric morphometrics to analyse shape configurations of landmarks within the standard statistical framework employed in studies of bilateral asymmetries, and we have extended these methods to partition the individual variation and the variation in asymmetries into genetic and environmental causal components. The analyses revealed temperature-dependent expression of genetic variation for wing size and wing shape, directional asymmetry (DA) of wing size, increased asymmetries at suboptimal temperature, and a transition from FA to DA in males as a result of increase in the rearing temperature. No genetic variation was generally detected for FA in our samples, but these are preliminary results because no crosses between lines were carried out and, therefore, the contribution of dominance was not taken into account. In addition, only a subset of the standing genetic variation was represented in the experiments.