The Drosophila wing has been used as a model to investigate the mechanisms responsible for size and shape changes in nature, since such changes might underlie morphological evolution. To improve the understanding of wing morphological variation and the interpretation of genetic parameters estimates, we have established 59 lines from a Drosophila simulans laboratory population through single pair random matings. The offspring of each line were reared at three different temperatures, and the wing morphology of 12 individuals was analyzed by adjusting an ellipse to the wings' contour. Temperature, sex and line significantly affected wing trait variation, which was mainly characterized by longer wings having the second, fourth and fifth longitudinal veins closer together at the wing tip. As for the genetic parameter estimates, while the cross-environment heritability of some traits, such as wing size (SI), decreased with an increasing difference between the temperatures at which parents and offspring were reared, wing shape (SH) heritability did not seem to change. Since we found indications that neither an increase in the phenotypic variation nor the occurrence of genotype-environment interactions could fully explain the low heritabilities of SI estimated by cross-environment regressions, we discuss the importance of other effects for explaining this discrepancy between the SI and SH heritability estimates. In addition, although the genetic matrix was not entirely represented in the phenotypic matrix, several correspondences were identified, suggesting that the observed patterns of wing morphology variation are genetically controlled.

Accurate estimation of gene expression differences during development requires sensitive techniques combined with gold-standard normalization procedures. This is particularly true in the case of quantitative traits, where expression changes might be small. Nevertheless, systematic selection and validation of reference genes has been overlooked, even in Drosophila studies. Here, we tested the stability of six traditional reference genes across samples of imaginal wing disks from morphologically divergent strains of Drosophila melanogaster, in a two-class comparison: quantitative or qualitative variation in wing morphology. Overall, we identified and validated a pair of genes (RpL32 and Tbp) as being stably expressed in both experimental comparisons. These genes might be considered as a bona fide pair of reference genes for gene expression analyses of morphological divergence in D. melanogaster wings. They might also be taken as good candidates for experimental identification of stable reference genes in other morphological comparisons using Drosophila or other insect species. Besides, we found that some genes traditionally used as reference in qPCR experiments were not stably expressed in wing disks from the different fly strains. In fact, a significant bias was observed when the expression of three genes of interest, which are involved in the regulation of growth and patterning during imaginal wing development, was normalized with such putative reference genes. Our results demonstrate how inaccurate findings and opposite conclusions might be drawn if traditional reference genes are arbitrarily used for internal normalization without proper validation in the given experimental condition, a practice still common in qPCR experiments.

Organ shape evolves through cross-generational changes in developmental patterns at cellular and/or tissue levels that ultimately alter tissue dimensions and final adult proportions. Here, we investigated the cellular basis of an artificially selected divergence in the outline shape of Drosophila melanogaster wings, by comparing flies with elongated or rounded wing shapes but with remarkably similar wing sizes. We also tested whether cellular plasticity in response to developmental temperature was altered by such selection. Results show that variation in cellular traits is associated with wing shape differences, and that cell number may play an important role in wing shape response to selection. Regarding the effects of developmental temperature, a size-related plastic response was observed, in that flies reared at 16 °C developed larger wings with larger and more numerous cells across all intervein regions relative to flies reared at 25 °C. Nevertheless, no conclusive indication of altered phenotypic plasticity was found between selection strains for any wing or cellular trait. We also described how cell area is distributed across different intervein regions. It follows that cell area tends to decrease along the anterior wing compartment and increase along the posterior one. Remarkably, such pattern was observed not only in the selected strains but also in the natural baseline population, suggesting that it might be canalized during development and was not altered by the intense program of artificial selection for divergent wing shapes.

Several studies have demonstrated the cost-effectiveness of genetic testing for surveillance and treatment of carriers of germline pathogenic variants associated with hereditary breast/ovarian cancer syndrome (HBOC). In Brazil, seventy percent of the population is assisted by the public Unified Health System (SUS), where genetic testing is still unavailable. And few studies were performed regarding the prevalence of HBOC pathogenic variants in this context. Here, we estimated the prevalence of germline pathogenic variants in BRCA1, BRCA2 and TP53 genes in Brazilian patients suspected of HBOC and referred to public healthcare service. Predictive power of risk prediction models for detecting mutation carriers was also evaluated. We found that 41 out of 257 tested patients (15.9%) were carriers of pathogenic variants in the analyzed genes. Most frequent pathogenic variant was the founder Brazilian mutation TP53 c.1010G > A (p.Arg337His), adding to the accumulated evidence that supports inclusion of TP53 in routine testing of Brazilian HBOC patients. Surprisingly, BRCA1 c.5266dupC (p.Gln1756fs), a frequently reported pathogenic variant in Brazilian HBOC patients, was not observed. Regarding the use of predictive models, we found that familial history of cancer might be used to improve selection or prioritization of patients for genetic testing, especially in a context of limited resources.

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