Genome size (or C-value) can present a wide range of values among eukaryotes. This variation has been attributed to differences in the amplification and deletion of different noncoding repetitive sequences, particularly transposable elements (TEs). TEs can be activated under different stress conditions such as interspecific hybridization events, as described for several species of animals and plants. These massive transposition episodes can lead to considerable genome expansions that could ultimately be involved in hybrid speciation processes. Here, we describe the effects of hybridization and introgression on genome size of Drosophila hybrids. We measured the genome size of two close Drosophila species, Drosophila buzzatii and Drosophila koepferae, their F1 offspring and the off spring from three generations of backcrossed hybrids; where mobilization of up to 28 different TEs was previously detected. We show that hybrid females indeed present a genome expansion, especially in the first backcross, which could likely be explained by transposition events. Hybrid males, which exhibit more variable-C values among individual soft he same generation, do not presentan increased genome size. Thus, we demonstrate that the impact of hybridization on genome size can be detected through flow cytometry and is sex-dependent.

Research on nanomaterial exposure-related health risks is still quite limited; this includes standardizing methods for measuring metals in living organisms. Thus, this study validated an atomic absorption spectrophotometry method to determine fertility and bioaccumulated iron content in Drosophila melanogaster flies after feeding them magnetite nanoparticles (Fe3O4NPs) dosed in a culture medium (100, 250, 500, and 1000 mg kg−1). Some NPs were also coated with chitosan to compare iron assimilation. Considering both accuracy and precision, results showed the method was optimal for concentrations greater than 20 mg L−1. Recovery values were considered optimum within the 95–105% range. Regarding fertility, offspring for each coated and non-coated NPs concentration decreased in relation to the control group. Flies exposed to 100 mg L−1 of coated NPs presented the lowest fertility level and highest bioaccumulation factor. Despite an association between iron bioaccumulation and NPs concentration, the 500 mg L−1 dose of coated and non-coated NPs showed similar iron concentrations to those of the control group. Thus, Drosophila flies’ fertility decreased after NPs exposure, while iron bioaccumulation was related to NPs concentration and coating. We determined this method can overcome sample limitations and biological matrix-associated heterogeneity, thus allowing for bioaccumulated iron detection regardless of exposure to coated or non-coated magnetite NPs, meaning this protocol could be applicable with any type of iron NPs.

Nanoparticles are a cause for concern because of their potential toxic effects on human health and the environment. The aim of this study was to assess the toxic effect of chitosan-coated magnetite nanoparticles (11.00±4.7 nm) on Drosophila melanogaster through the observation of hemolymph composition, DNA damage, larval survival and lifespan of flies. Chitosan-coated magnetite nanoparticles were synthesized by co[1]precipitation method. Drosophila larvaes and adults were exposed to 500 and 1000 ppm nanoparticles solution. After exposure, each type of larval hemocytes was recognized. Comet assay was performed to detect the DNA damage in the hemocytes. Also, the larval survival and lifespan of exposed flies were observed. Our results showed the toxic effect of the chitosan-coated magnetite nanoparticles through the increment of hemocytes, the emergence of lamellocytes, the presence of apoptotic hemocytes and the DNA damage detected by comet assay. In addition, nanoparticles produce decreasing of larval survival and shortening of the mean and maximum lifespan. The toxic effect the chitosan-coated magnetite nanoparticles is directly associated with 1000 ppm. No DNA damage was observed at 500 ppm.