Comparative Cytogenetics of the Malagasy Ground Geckos of the Paroedura bastardi and Paroedura picta Species Groups.

We present a comparative chromosome study of several taxa of the Malagasy ground geckos of the Paroedura bastardi and P. picta species groups. We employed a preliminary molecular analysis using a trait of the mitochondrial 16S rRNA gene (of about 570 bp) to assess the taxonomic status of the samples studied and a cytogenetic analysis with standard karyotyping (5% Giemsa solution), silver staining (Ag-NOR staining) and sequential C-banding (C-banding + Giemsa and + fluorochromes). Our results show that all the taxa studied of the P. bastardi group (P. ibityensis, P. rennerae and P. cf. guibeae) have a similar karyotype composed of 2n = 34 chromosomes, with two metacentric pairs (1 and 3) and all other pairs being acrocentric. Chromosome diversification in the P. bastardi group was mainly linked to the diversification of heteromorphic sex chromosome systems (ZZ/ZW) in P. ibityensis and P. rennerae, while no heteromorphic sex chromosome pair was found in P. cf. guibeae. The two taxa investigated of the P. picta species group (here named P. picta and P. cf. picta based on molecular data) showed the same chromosome number of 2n = 36, mostly acrocentric elements, but differed in the number of metacentric elements, probably as a result of an inversion at chromosome pair 2. We highlight that the genus Paroedura is characterized by the independent diversification of heterogametic sex chromosomes in different evolutionary lineages and, similarly to other phylogenetically related gecko genera, by a progressive formation of a biarmed element by means of tandem fusions and inversions of distinct pairs.

Effect of short-term exposure to the strobilurin fungicide dimoxystrobin: Morphofunctional, behavioural and mitochondrial alterations in Danio rerio embryos and larvae.

Strobilurins, among the most used fungicides worldwide, are considered non-toxic to mammals and birds, but there is growing evidence that these compounds are highly toxic to aquatic species. Dimoxystrobin has been included in the 3rd Watch List of the European Commission, and it has been classified as very toxic to aquatic life. However, previous studies focused on acute toxicity and only two reports are available on its impact on fish, and none on its effects during the early life stages. Here, we evaluated for the first time the effects induced on zebrafish embryos and larvae by two dimoxystrobin sublethal concentrations (6.56 and 13.13 µg/L) falling in the range of predicted environmental concentrations. We demonstrated that short-term exposure to dimoxystrobin may exert adverse effects on multiple targets, inducing severe morphological alterations. Moreover, we showed enhanced mRNA levels of genes related to the mitochondrial respiratory chain and ATP production. Impairment of the swim bladder inflation has also been recorded, which may be related to the observed swimming performance alterations.

Eye morphology in four species of tiger beetles (Coleoptera: Cicindelidae).

Compound eyes undoubtedly represent the widespread eye architecture in the animal kingdom. The insects' compound eye shows a wide variety of designs, and insects use their visual capacity to accomplish several tasks, including avoiding enemies, searching for food and shelter, locating a mate, and acquiring information about the environment and its surroundings. Broad literature data support the concept that visual ability lies in the way the eyes are built. Since the resolution and sensitivity of the compound eye are partly determined by the density of the ommatidia and the size of the facets. Morphological parameters of the compound eyes could influence the function of the visual organ and its capacity to process information, also representing a sensitive indicator of different habitat demands. In this study, we compared compound eyes' parameters in four closely related species of tiger beetles to disclose differences arising from different habitats. Furthermore, to investigate whether there are consistent intersexual differences, we also compared the most relevant parameters of the eye in males and females of four selected species. Our results show sex-related and interspecific differences that occur in examined species.

Karyotype Diversification and Chromosome Rearrangements in Squamate Reptiles.

Karyotype diversification represents an important, yet poorly understood, driver of evolution. Squamate reptiles are characterized by a high taxonomic diversity which is reflected at the karyotype level in terms of general structure, chromosome number and morphology, and insurgence of differentiated simple or multiple-sex-chromosome systems with either male or female heterogamety. The potential of squamate reptiles as unique model organisms in evolutionary cytogenetics has been recognised in recent years in several studies, which have provided novel insights into the chromosome evolutionary dynamics of different taxonomic groups. Here, we review and summarize the resulting complex, but promising, general picture from a systematic perspective, mapping some of the main squamate karyological characteristics onto their phylogenetic relationships. We highlight how all the major categories of balanced chromosome rearrangements contributed to the karyotype evolution in different taxonomic groups. We show that distinct karyotype evolutionary trends may occur, and coexist, with different frequencies in different clades. Finally, in light of the known squamate chromosome diversity and recent research advances, we discuss traditional and novel hypotheses on karyotype evolution and propose a scenario of circular karyotype evolution.

The Ephrin tyrosine kinase a3 (EphA3) is a novel mediator of RAGE-prompted motility of breast cancer cells.

BACKGROUND: The receptor for advanced glycation-end products (RAGE) and its ligands have been implicated in obesity and associated inflammatory processes as well as in metabolic alterations like diabetes. In addition, RAGE-mediated signaling has been reported to contribute to the metastatic progression of breast cancer (BC), although mechanistic insights are still required. Here, we provide novel findings regarding the transcriptomic landscape and the molecular events through which RAGE may prompt aggressive features in estrogen receptor (ER)-positive BC. METHODS: MCF7 and T47D BC cells stably overexpressing human RAGE were used as a model system to evaluate important changes like cell protrusions, migration, invasion and colony formation both in vitro through scanning electron microscopy, clonogenic, migration and invasion assays and in vivo through zebrafish xenografts experiments. The whole transcriptome of RAGE-overexpressing BC cells was screened by high-throughput RNA sequencing. Thereafter, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses allowed the prediction of potential functions of differentially expressed genes (DEGs). Flow cytometry, real time-PCR, chromatin immunoprecipitation, immunofluorescence and western blot assays were performed to investigate the molecular network involved in the regulation of a novel RAGE target gene namely EphA3. The clinical significance of EphA3 was explored in the TCGA cohort of patients through the survivALL package, whereas the pro-migratory role of EphA3 signaling was ascertained in both BC cells and cancer-associated fibroblasts (CAFs). Statistical analysis was performed by t-tests. RESULTS: RNA-seq findings and GSEA analysis revealed that RAGE overexpression leads to a motility-related gene signature in ER-positive BC cells. Accordingly, we found that RAGE-overexpressing BC cells exhibit long filopodia-like membrane protrusions as well as an enhanced dissemination potential, as determined by the diverse experimental assays. Mechanistically, we established for the first time that EphA3 signaling may act as a physical mediator of BC cells and CAFs motility through both homotypic and heterotypic interactions. CONCLUSIONS: Our data demonstrate that RAGE up-regulation leads to migratory ability in ER-positive BC cells. Noteworthy, our findings suggest that EphA3 may be considered as a novel RAGE target gene facilitating BC invasion and scattering from the primary tumor mass. Overall, the current results may provide useful insights for more comprehensive therapeutic approaches in BC, particularly in obese and diabetic patients that are characterized by high RAGE levels.

Chromosome Diversity and Evolution of the Endemic Malagasy Velvet Geckos of the Genus Blaesodactylus (Reptilia, Gekkonidae).

We performed a molecular and phylogenetic analysis and a comparative cytogenetic study with standard karyotyping, silver staining (Ag-NOR) and sequential C-banding + Giemsa, + fluorochromes on several Blaesodactylus samples. The phylogenetic inference retrieved two main clades, the first comprises B. victori, B. microtuberculatus and B. boivini, while the second includes B. sakalava, B. antongilensis and B. ambonihazo. The available samples of B. sakalava form two different clades (here named B. sakalava clade A and clade B), which probably deserve a taxonomic re-evaluation. We found a karyological variability in Blaesodactylus in terms of chromosome number (2n = 40-42), morphology, location of NORs, and heterochromatin distribution pattern. Blaesodactylus antongilensis and B. sakalava clade A and B showed a karyotype of 2n = 40 mostly telocentric chromosomes. Pairs 1 and 6 were metacentric in B. sakalava clade A and B, while pair 1 was composed of subtelocentric/submetacentric elements in B. antongilensis. In contrast, B. boivini displayed a karyotype with 2n = 42 only telocentric chromosomes. NORs were on the first chromosome pair in B. boivini, and on the second pair in B. antongilensis. Adding our data to those available from the literature on evolutionarily related species, we highlight that the chromosome diversification in the genus probably proceeded towards a progressive reduction in the chromosome number and the formation of metacentric elements.

Short-term effects of the strobilurin fungicide dimoxystrobin on zebrafish gills: A morpho-functional study.

Strobilurins represent the most widely used class of fungicides nowadays andare considered relatively non-toxic to mammals and birds but highly toxic to aquatic biota. Dimoxystrobin is one of the novel strobilurins, recently included in the 3rd Watch List of the European Commission as available data indicate that it could pose a significant risk to aquatic species. As yet, the number of studies explicitly assessing the impact of this fungicide on terrestrial and aquatic species is extremely low, and the toxic effects of dimoxystrobin on fish have not been reported. Here we investigate for the first time the alterations induced by two environmentally relevant and very low concentrations of dimoxystrobin (6.56 and 13.13 µg/L) in the fish gills. morphological, morphometric, ultrastructural, and functional alterations have been evaluated using zebrafish as a model species. We demonstrated that even short-term exposure (96 h) to dimoxystrobin alters fish gills reducing the surface available for gas exchange and inducing severe alterations encompassing three reaction patterns: circulatory disturbance and both regressive and progressive changes. Furthermore, we revealed that this fungicide impairs the expression of key enzymes involved in osmotic and acid-base regulation (Na+/K+-ATPase and AQP3) and the defensive response against oxidative stress (SOD and CAT). The information presented here highlights the importance of combining data from different analytical methods for evaluating the toxic potential of currently used and new agrochemical compounds. Our results will also contribute to the discussion on the suitability of mandatory ecotoxicological tests on vertebrates before the introduction on the market of new compounds.

Evolutionary and Genomic Diversity of True Polyploidy in Tetrapods.

True polyploid organisms have more than two chromosome sets in their somatic and germline cells. Polyploidy is a major evolutionary force and has played a significant role in the early genomic evolution of plants, different invertebrate taxa, chordates, and teleosts. However, the contribution of polyploidy to the generation of new genomic, ecological, and species diversity in tetrapods has traditionally been underestimated. Indeed, polyploidy represents an important pathway of genomic evolution, occurring in most higher-taxa tetrapods and displaying a variety of different forms, genomic configurations, and biological implications. Herein, we report and discuss the available information on the different origins and evolutionary and ecological significance of true polyploidy in tetrapods. Among the main tetrapod lineages, modern amphibians have an unparalleled diversity of polyploids and, until recently, they were considered to be the only vertebrates with closely related diploid and polyploid bisexual species or populations. In reptiles, polyploidy was thought to be restricted to squamates and associated with parthenogenesis. In birds and mammals, true polyploidy has generally been considered absent (non-tolerated). These views are being changed due to an accumulation of new data, and the impact as well as the different evolutionary and ecological implications of polyploidy in tetrapods, deserve a broader evaluation.

First Insights on the Karyotype Diversification of the Endemic Malagasy Leaf-Toed Geckos (Squamata: Gekkonidae: Uroplatus).

We provide here the first karyotype description of eight Uroplatus species and a characterization of their chromosomal diversity. We performed a molecular taxonomic assessment of several Uroplatus samples using the mitochondrial 12S marker and a comparative cytogenetic analysis with standard karyotyping, silver staining (Ag-NOR) and sequential C-banding + Giemsa, +Chromomycin A3 (CMA3), +4',6-diamidino-2-phenylindole (DAPI). We found chromosomal variability in terms of chromosome number (2n = 34-38), heterochromatin composition and number and localization of loci or Nucleolar Organizer Regions (NORs) (alternatively on the 2nd, 6th, 10th or 16th pair). Chromosome morphology is almost constant, with karyotypes composed of acrocentric chromosomes, gradually decreasing in length. C-banding evidenced a general low content of heterochromatin, mostly localized on pericentromeric and telomeric regions. Centromeric bands varied among the species studied, resulting in CMA3 positive and DAPI negative or positive to both fluorochromes. We also provide evidence of a first putative heteromorphic sex chromosome system in the genus. In fact, in U. alluaudi the 10th pair was highly heteromorphic, with a metacentric, largely heterochromatic W chromosome, which was much bigger than the Z. We propose an evolutionary scenario of chromosome reduction from 2n = 38 to 2n = 34, by means of translocations of microchromosomes on larger chromosomes (often involving the NOR-bearing microchromosomes). Adding our data to those available from the literature, we show that similar processes characterized the evolutionary radiation of a larger gecko clade. Finally, we hypothesize that sex chromosome diversification occurred independently in different genera.

The role of exposure window and dose in determining lead toxicity in developing Zebrafish.

Heavy metal contamination is recognized worldwide as a serious threat to human health and wildlife, and reducing their emissions is a priority of international and EU actions. Due to its persistence, high bioaccumulation tendency, and toxicity properties, lead (Pb) is one of the heavy metals of greatest concern. Even at low concentrations, lead induces various clinical and subclinical conditions in both humans and animals, and it has been included in the priority list of hazardous substances. In the present study, we used zebrafish's early stages as a model, given their well-acknowledged predictive value in the risk assessment of chemicals. This study was designed to investigate the morphological and morphometric alterations induced by Pb during zebrafish's early development and disclose the putative effects stage- and/or dose-dependent. We examined injuries induced by two environmentally relevant and extremely low concentrations of Pb (2.5 µg/L and 5 µg/L) during two exposure windows: early (between 1 and 7 dpf) and late (between 2 and 8 dpf). We clearly demonstrated that the incidence and severity of morphological abnormalities increased with increasing Pb dose and exposure time in both early and late-exposed groups. Furthermore, we revealed that malformation severity was significantly higher in the early exposed group than in the late exposure group at all exposure times and for both tested doses, thus highlighting the high sensitivity of zebrafish during the initial stages of development. The information presented in this paper emphasizes the effectiveness of morphological biomarkers in unveiling threatening situations and supports the role of zebrafish embryos and larvae in risk assessment and environmental monitoring.