Heterochromatin and karyotypic differentiation of some neotropical cactus-breeding species of the Drosophila repleta species group

Metaphase chromosomes from neuroblasts of strains from both laboratory stocks and natural populations of D. serido, D. meridionalis, D. borborema and D. buzzatii have been studied using colcemid pretreatment, and air-drying followed by Giemsa staining. The two latter species both show a uniform ‘basic’ metaphase karyotype. D. serido and D. meridionalis, on the other hand, both include a number of different, geographically distinct, metaphase karyotypes involving differences in the major blocks of constitutive heterochromatin present on the sex chromosomes and/or the 6th chromosome (microchromosome). These chromosomal differences are largely due to the acquisition of extra heterochromatin though pericentric inversions appear to be responsible for some of the Y-chromosome variants in D. serido. Moreover, the cytological evidence demonstrates that populations of both species are far from continuous in distribution. The extent to which such cytological differences reflect the existence of subspecific or specific complexes with minimal morphological differentiation is under investigation.     

Divergence in wing morphology among sibling species of the Drosophila buzzatii cluster

The Drosophila buzzatii species cluster consists of the sibling species D. buzzatii, D. koepferae, D. serido, D. borborema, D. seriema, D. antonietae and D. gouveai, all of which breed exclusively in decaying cactus tissue and, except for D. buzzatii (a colonizing subcosmopolitan species), are endemic to South America. Using a morphometric approach and multivariate analysis of 17 wing parameters, we investigated the degree of divergence in wing morphology among the sibling species of this cluster. Significant differences were obtained among the species and discriminant analysis showed that wing morphology was sufficiently different to allow the correct classification of 98.6% of the 70 individuals analysed. The phenetic relationships among the species inferred from UPGMA cluster analysis based on squared Mahalanobis distances (D²) were generally compatible with previously published phylogenetic relationships. These results suggest that wing morphology within D. buzzatii cluster is of phylogenetic importance.     

Allozyme and chromosomal polymorphism ofDrosophila buzzatii in Brazil and Argentina

Allozyme polymorphism in the colonizing populations ofD. buzzatii in Australia is quite low (average heterozygosity of 0.051 ± 0.025), but no comparative data are available for the species in other introduced populations or in its presumed area of origin, the Chaco of Argentina. For 12 localities in Argentina and five in Brazil, average expected heterozygosity is not significantly different from that in Australia. However, there appears to have been a loss of genetic variability on introduction of the species to Australia, as five loci are variable in South America that are monomorphic in Australia, and one additional allele was detected at each of six other loci in South America. Our results for inversion polymorphism in Argentina are consistent with previous data, but some Brazilian populations apparently have reduced inversion polymorphism. With the exception of those nearest the Chaco, these Brazilian populations may have resulted from passive colonization within historical times due to transport by man, and could represent both primary and secondary colonizations. However, the allozyme data do not readily fit a colonization hypothesis, and theD. buzzatii populations of both northeast and southeast Brazil may be relic populations. More detailed study of inversion and allozyme polymorphism in Brazil is necessary to provide critical data on the evolutionary history of this species.     

Population Genetic Structure of Two Columnar Cacti with a Patchy Distribution in Eastern Brazil

The genetic variability and population genetic structure of six populations of Praecereus euchlorus and Pilosocereus machrisii were investigated. The genetic variability in single populations of Pilosocereus vilaboensis, Pilosocereus aureispinus, and Facheiroa squamosa was also examined. All of these cacti species have a patchy geographic distribution in which they are restricted to small areas of xeric habitats in eastern Brazil. An analysis of genetic structure was used to gain insights into the historical mechanisms responsible for the patchy distribution of P. euchlorus and P. machrisii. High genetic variability was found at the populational level in all species (P=58.9–92.8%, A_p=2.34–3.33, H_e=0.266–0.401), and did not support our expectations of low variability based on the small population size. Substantial inbreeding was detected within populations (F_IS=0.370–0.623). In agreement with their insular distribution patterns, P. euchlorus and P. machrisii had a high genetic differentiation (F_ST=0.484 and F_ST=0.281, respectively), with no evidence of isolation by distance. Accordingly, estimates of gene flow (N_m) calculated from F_ST and private alleles were below the level of N_m=1 in P. machrisii and P. euchlorus. These results favored historical fragmentation as the mechanism responsible for the patchy distribution of these two species. The genetic distance between P. machrisii and P. vilaboensis was not compatible with their taxonomic distinction, indicating a possible local speciation event in this genus, or the occurrence of introgression events.     

Characterisation and Interpopulation Variability of a Complex HpaI Satellite DNA of Drosophila seriema (repleta Group)

A HpaI satellite DNA has been isolated and characterised from the genome of Drosophila seriema, a cactus-breeding species endemic to the rock fields of the Espinhaço Range in Brazil. The monomer sequences are slightly A + T rich (66%) and there is a significant variation of repetition length (343–391 bp). The length variability is mainly due to a 22 bp indel in some repeats and the presence of a highly variable region characterised by several DNA rearrangements, including indels, inversions and duplications of small sequence segments. The retarded mobility of monomers observed after gel electrophoresis suggests DNA curvature. Thirty satDNA repeats were analysed in samples from five populations which cover D. seriema geographical distribution. Previous studies showed that these populations present low levels of chromosomal divergence in contrast to high levels of mtDNA divergence. The variability among the 30 repeats is pretty low, on average 2%. The results showed that the satDNA sequences are rather homogeneous on both intra and interpopulational levels, presenting no specific feature(s) that could discriminate a particular population or groups of geographically close populations. Possible factors responsible for such homogeneity are discussed.     

Vitamin D3 affects mitochondrial biogenesis through mitogen-activated protein kinase in polycystic ovary syndrome mouse model

Polycystic ovarian syndrome (PCOS) is a disorder characterized by oligomenorrhea, anovulation, and hyperandrogenism. Altered mitochondrial biogenesis can result in hyperandrogenism. The goal of this study was to examine the effect of vitamin D3 on mitochondrial biogenesis of the granulosa cells in the PCOS-induced mouse model. Vitamin D3 applies its effect via the mitogen-activated pathway kinase-extracellular signal-regulated kinases (MAPK-ERK1/2) pathway. The PCOS mouse model was induced by the injection of dehydroepiandrosterone (DHEA). Isolated granulosa cells were subsequently treated with vitamin D3, MAPK activator, and MAPK inhibitor. Gene expression levels were measured using real-time polymerase chain reaction. MAPK proteins were investigated by western blot analysis. We also determined reactive oxygen species (ROS) levels with 2′, 7′-dichlorofluorescein diacetate. Mitochondrial membrane potential (mtMP) was also measured by TMJC1. Mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator 1-α and nuclear respiratory factor), antioxidant (superoxide dismutase, glutathione peroxidase, and catalase), and antiapoptotic (B-cell lymphoma-2) genes were upregulated in the PCOS mice that treated with vitamin D3 compared with the PCOS mice without any treatment. Vitamin D3 and MAPK activator-treated groups also reduced ROS levels compared with the nontreated PCOS group. In summary, vitamin D3 and MAPK activator increased the levels of mitochondrial biogenesis, MAPK pathway, and mtMP markers, while concomitantly decreased ROS levels in granulosa cells of the PCOS-induced mice. This study suggests that vitamin D3 may improve mitochondrial biogenesis through stimulation of the MAPK pathway in cultured granulosa cells of DHEA-induced PCOS mice which yet to be investigated.     

Involvement of Renal Corpuscle microRNA Expression on Epithelial-to-Mesenchymal Transition in Maternal Low Protein Diet in Adult Programmed Rats

Prior study shows that maternal protein-restricted (LP) 16-wk-old offspring have pronounced reduction of nephron number and arterial hypertension associated with unchanged glomerular filtration rate, besides enhanced glomerular area, which may be related to glomerular hyperfiltration/overflow and which accounts for the glomerular filtration barrier breakdown and early glomerulosclerosis. In the current study, LP rats showed heavy proteinuria associated with podocyte simplification and foot process effacement. TGF-β1 glomerular expression was significantly enhanced in LP. Isolated LP glomeruli show a reduced level of miR-200a, miR-141, miR-429 and ZEB2 mRNA and upregulated collagen 1α1/2 mRNA expression. By western blot analyzes of whole kidney tissue, we found significant reduction of both podocin and nephrin and enhanced expression of mesenchymal protein markers such as desmin, collagen type I and fibronectin. From our present knowledge, these are the first data showing renal miRNA modulation in the protein restriction model of fetal programming. The fetal-programmed adult offspring showed pronounced structural glomerular disorders with an accentuated and advanced stage of fibrosis, which led us to state that the glomerular miR-200 family would be downregulated by TGF-β1 action inducing ZEB 2 expression that may subsequently cause glomeruli epithelial-to-mesenchymal transition.     

Microsatellite and morphometric variation in Drosophila gouveai: the relative importance of historical and current factors in shaping the genetic population structure

Drosophila gouveai is a cactus-breeding species with a naturally fragmented distribution in central-western and southeastern Brazil. In this study, a neutral genetic marker (microsatellite DNA) and a quantitative trait (wing morphology) were used to investigate the population structure of eight populations of D. gouveai . Quantitative analysis was done using a morphometric approach and multivariate analysis of 17 wing parameters. Drosophila gouveai showed a large degree of genetic population differentiation ( F _ST = 0.245). A molecular analysis of variance showed that the population structure was attributable mainly to genetic differences among the population groups, which were correlated with regional groupings. A Bayesian cluster analysis also identified the same regional groupings as contributing to the population structure. Assignment tests revealed that the current gene flow was very restricted. The divergence in wing morphology among populations was also high, and revealed a geographical pattern that conformed to a latitudinal cline. In contrast to current factors such as migration-drift equilibrium, these results indicated that the genetic population structure of D. gouveai was shaped predominantly by historical factors.     

Breeding structure of an isolated cactophilic Drosophila population on a sandstone table hill

The effect of host cacti on the breeding structure of an isolated population of cactophilic Drosophila gouveai was studied. A comparison was made, using F statistics, of the allozyme frequencies at 11 loci among temporal samples of the adult population and six samples of progeny obtained from individual rotting cactus cladodes. The population appears to be structured by the cacti, forming breeding groups, and approximately four individuals contribute gametes to the progeny of each cladode. This D. gouveai population had a low degree of heterozygosity, compared with mean values for most Drosophila species, however it was within the range of values reported for other cactophilic Drosophila.