Chromosomal organization of four classes of repetitive DNA sequences in killifish Orestias ascotanensis Parenti, 1984 (Cyprinodontiformes, Cyprinodontidae).

Orestias Valenciennes, 1839 is a genus of freshwater fish endemic to the South American Altiplano. Cytogenetic studies of these species have focused on conventional karyotyping. The aim of this study was to use classical and molecular cytogenetic methods to identify the constitutive heterochromatin distribution and chromosome organization of four classes of repetitive DNA sequences (histone H3 DNA, U2 snRNA, 18S rDNA and 5S rDNA) in the chromosomes of O. ascotanensis Parenti, 1984, an endemic species restricted to the Salar de Ascotán in the Chilean Altiplano. All individuals analyzed had a diploid number of 48 chromosomes. C-banding identified constitutive heterochromatin mainly in the pericentromeric region of most chromosomes, especially a GC-rich heterochromatic block of the short arm of pair 3. FISH assay with an 18S probe confirmed the location of the NOR in pair 3 and revealed that the minor rDNA cluster occurs interstitially on the long arm of pair 2. Dual FISH identified a single block of U2 snDNA sequences in the pericentromeric regions of a subtelocentric chromosome pair, while histone H3 sites were observed as small signals scattered in throughout the all chromosomes. This work represents the first effort to document the physical organization of the repetitive fraction of the Orestias genome. These data will improve our understanding of the chromosomal evolution of a genus facing serious conservation problems.

Cytokine expression in peripheral blood lymphocytes indicates a switch to T(HELPER) cells in patients with preeclampsia.

We sought to determine whether cytokine expression in peripheral blood mononuclear cells is altered in patients with preeclampsia and in patients with a history of recurrent spontaneous abortion (RSA). Twenty-four patients with preeclampsia and twenty patients with a history of RSA were included into the study. Two control groups consisted of twenty healthy pregnant and twenty healthy non-pregnant women. The intracellular expression of interleukin-2 (IL-2), interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) were determined in peripheral blood mononuclear cells (PBMCs) by flow cytometry as a measure of cytokine production. IL-2 synthesis was significantly elevated in the third trimester in preeclamptic patients in comparison with the control group. Non-pregnant women with RSA showed a significantly lower expression of IFN-gamma compared to the non-pregnant control group. Our data suggest an abnormal immune response in preeclamptic patients characterised by a shift to a predominantly Th1-type immunity.