MHC diversity, malaria and lifetime reproductive success in collared flycatchers

Major histocompatibility complex (MHC) genes encode proteins involved in the recognition of parasite-derived antigens. Their extreme polymorphism is presumed to be driven by co-evolution with parasites. Host-parasite co-evolution was also hypothesized to optimize within-individual MHC diversity at the intermediate level. Here, we use unique data on lifetime reproductive success (LRS) of female collared flycatchers to test whether LRS is associated with within-individual MHC class II diversity. We also examined the association between MHC and infection with avian malaria. Using 454 sequencing, we found that individual flycatchers carry between 3 and 23 functional MHC class II B alleles. Predictions of the optimality hypothesis were not confirmed by our data as the prevalence of blood parasites decreased with functional MHC diversity. Furthermore, we did not find evidence for an association between MHC diversity and LRS.     

Regio- and stereoselectivity in preparation of 2-deoxysugar glycoglycerolipid derivatives evaluated by high resolution 1H NMR

New glycoglycerolipids, derivatives of 2-deoxysugars bearing one or two fatty acid chains have been synthesised. Various levels of regio- and stereoselectivity have been attained for the triphenylphosphine hydrobromide (TPHB) catalysed addition of the glycerol moiety to some representative glycals. The influence of the structure of glycal derivatives in glycosylation reactions is discussed.     

Density of Sgt1-immunopositive neurons is decreased in the cerebral cortex of Alzheimer's disease brain

Sgt1 was discovered as a protein required for the mitotic activity of kinetochore and for the activity of ubiquitin ligase in yeast [Kitagawa, K., Skowyra, D., Elledge, S.J., Harper, J.W., Hieter, P., 1999. SGT1 encodes an essential component of the yeast kinetochore assembly pathway and a novel subunit of the SCF ubiquitin ligase complex. Mol. Cell 4, 21-33.]. Later, Sgt1 was identified in different organisms including mammals where it was found at high level in the brain. To understand Sgt1 function in this tissue we analyzed its localization in human brain by immunohistochemistry. In normal brain we observed Sgt1-immunostaining in Purkinje cells of the cerebellum, in granule cells of the dentate gyrus of the hippocampus and in multiple neurons of the cortex. By Western blotting we found a higher level of this protein in the cortex than in the cerebellum. Subsequent morphometric analyses showed that the density of Sgt1-immunopositive neurons varied in different cortical regions. The highest density of Sgt1-immunopositive cells was seen in the temporal cortex (from 1.2% to 5.7%), and the lowest - in the entorhinal cortex (from 0 to 1.1% of all neurons). We next compared the density of Sgt1-immunopositive neurons in cortical layers of healthy aged and Alzheimer's disease (AD) brain sections. A significant decrease in Sgt1-immunopositive neurons was found in the temporal (up to 25-fold), angular (up to 11-fold) and posterior cingulate cortex (up to five-fold). In the entorhinal and precentral cortex the reduction of Sgt1-immunopositive neurons was only about two-fold in AD brains as compared to healthy aged ones. The presence of Sgt1 in post-mitotic neurons indicates the involvement of this protein in a process different from that required for activity of the kinetochore. Decreased immunostaining in AD cortex point to Sgt1 as a possible marker of neurons degenerating in AD.     

Interleukin-2 (IL-2) expression in livers of patients with chronic hepatitis C virus (HCV) infection

The studies performed till now have pointed to an increased serum levels of interleukin 2 (IL-2) in infection with hepatitis C virus (HCV). The present study was aimed at examining intrahepatic expression of IL-2 in children (n=15) and in adults (n=11) with chronic hepatitis C as well as its correlations with histological lesions and selected clinical data. The immunocytochemical techniques and in situ hybridization method were applied at light and electron microscopy level. Under the light microscope, expression of IL-2 was analysed semiquantitatively. As compared to the control material, in livers of both groups of chronic hepatitis C patients augmented expression of IL-2 was demonstrated. The reaction product was localized mainly in the cytoplasm of hepatocytes which was confirmed by hybridocytochemistry. The mean proportion of cells with positive reaction for IL-2 mRNA was significantly lower than the proportion of cells positive for the respective protein. No correlation was disclosed between IL-2 expression on one hand and grading or staging, alanine aminotransferase (ALT) and HCV RNA levels in serum on the other. At the ultrastructural level, IL-2 in hepatocytes was present mainly in the endoplasmic reticulum and mitochondria. Our studies have confirmed augmented expression of IL-2 in livers of patients with chronic hepatitis C and have demonstrated that hepatocytes represent the principal source of the cytokine in HCV in vivo infection. Moreover, expression of IL-2 in the infection was examined for the first time at the ultrastructural level. Mitochondrial localization of IL-2 suggests a direct involvement of the cytokine in disturbed function of the organelles.     

Unsaturated genistein disaccharide glycoside as a novel agent affecting microtubules

Genistein, due to its recognized chemopreventive and antitumor potential, is a molecule of interest as a lead compound in drug design. While multiple molecular targets for genistein have been identified, so far neither for this isoflavonoid nor for its natural or synthetic derivatives disruption of microtubules and mitotic spindles has been reported. Here we describe such properties of the synthetic glycosidic derivative of genistein significantly more cytotoxic than genistein, 7-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-(1→4)-(6-O-acetyl-hex-2-ene-α-d-erythro-pyranosyl)genistein, shortly named G21. We found that G21 causes significant mitotic delay, frequent appearance of multipolar spindles, and alteration of the interphase microtubule array.     

S100A6 - New facts and features

S100A6 (calcyclin) is a 10.5 kDa Ca²⁺-binding protein that belongs to the S100 protein family. S100A6 contains two EF-hand motifs responsible for binding of Ca²⁺. It also binds Zn²⁺ through not yet identified structures. Binding of Ca²⁺ induces a conformational change in the S100A6 molecule which in consequence increases its overall hydrophobicity and allows for interaction with target proteins. S100A6 was found in different mammalian and avian (chicken) tissues. A high level of S100A6 is observed in epithelial cells, fibroblasts and in different kinds of cancer cells. The function of S100A6 is not clear at present, but it has been suggested that it may be involved in cell proliferation, cytoskeletal dynamics and tumorigenesis. Additionally, S100A6 might have some extracellular activities. This review presents new facts and features concerning the S100A6 protein.     

S100A6 (calcyclin) deficiency induces senescence‐like changes in cell cycle,morphology and functional characteristics of mouse NIH 3T3 fibroblasts

S100A6 (calcyclin) is a calcium binding protein with two EF‐hand structures expressed mostly in fibroblasts and epithelial cells. We have established a NIH 3T3 fibroblast cell line stably transfected with siRNA against S100A6 to examine the effect of S100A6 deficiency on non‐transformed cell physiology. We found that NIH 3T3 fibroblasts with decreased level of S100A6 manifested altered cell morphology and proliferated at a much slower pace than the control cells. Cell cycle analysis showed that a large population of these cells lost the ability to respond to serum and persisted in the G0/G1 phase. Furthermore, fibroblasts with diminished S100A6 level exhibited morphological changes and biochemical features of cellular senescence as revealed by β‐galactosidase and gelatinase assays. Also, S100A6 deficiency induced changes in the actin cytoskeleton and had a profound impact on cell adhesion and migration. Thus, we have shown that the S100A6 protein is involved in multiple aspects of fibroblast physiology and that its presence ensures normal fibroblast proliferation and function. J. Cell. Biochem. 109: 576–584, 2010. © 2009 Wiley‐Liss, Inc.     

Influence of heavy metals and 4-nonylphenol on reproductive function in fish

Many industrial and agricultural chemicals (including heavy metals and alkylphenols) present in the environment have adverse effects on the reproductive function in fish. Three studies were conducted to assess toxicity of these chemicals towards reproduction of freshwater fish. It was shown that heavy metals added to the diets accumulate in brain tissue of carp, and this accumulation results in inhibition of the secretion of noradrenaline and stimulation of the secretion of dopamine in the hypothalamus. These processes results in a disturbance of hormonal equilibrium of the hypothalamo-pituitary system, which can unfavorably influence the efficiency of artificial spawning in fish. Quality of salmonid and sturgeon sperm was impaired after in vitro exposure to heavy metals. The degree of this toxic effect was species-specific. It was demonstrated that sperm motility parameters appeared to be good indicators of adverse effects of heavy metals fish sperm. The protection role of seminal plasma against toxic effects of heavy metals was suggested for salmonid fish. Oral application of 4-nonylphenol (NP) disrupted reproduction in pikeperch. In juvenile fish a decrease in the percentage of males and an increase of intersex fish was observed in relation to dose of NP and time of exposure to this alkylphenol. Exposure of adult males to the NP led to the reduction in fecundity, milt quality and fertility.     

Ovulation level and prolificacy in ewes depending on their age, birth type and percentage of prolific genotype

During December mating periods of 2000-2003, wool and meat breeds crossed with East Friesian milk sheep and rams of prolific breeds (Finn or Romanov) were examined laparoscopically. Ovine ovaries were examined between 4 and 9 days after mating. The litter size was recorded and compared with the number of ovulations. The fertility of the analyzed animals was 69.6%, with 192.6% prolificacy. The difference between the average number of corpora lutea found on ovaries and the mean number of lambs born was 0.35 and ranged from 0.32 to 0.41 according to age group, from 0.22 to 0.41 according to sheep birth type, and from 0 to 0.52 lamb per ewe according to percentage of prolific breeds.