Food habits and prey selection of three species of groupers from the genus Cephalopholis (Serranidae: Teleostei)

Synopsis This paper describes a study performed in the Gulf of Aqaba on food selectivity and hunting behaviour of three species of sympatric fish from the genusCephalopholis. These fishes occur in the shallow-water coral habitats of the Red Sea and feed on fishes and invertebrates. Of these,C. argus andC. miniata prefer selected fish species (95 and 86% of their diet respectively), whereasC. hemistiktos consumes more invertebrates (36%) and is less selective with respect to fish species. All three species employ various techniques to catch their prey and in situations where their elected food is absent they readily switch to substitute prey species.     

Dissecting the molecular architecture and origin of Bayash Romani patrilineages: genetic influences from South-Asia and the Balkans

The Bayash are a branch of Romanian speaking Roma living dispersedly in Central, Eastern, and Southeastern Europe. To better understand the molecular architecture and origin of the Croatian Bayash paternal gene pool, 151 Bayash Y chromosomes were analyzed for 16 SNPs and 17 STRs and compared with European Romani and non-Romani majority populations from Europe, Turkey, and South Asia. Two main layers of Bayash paternal gene pool were identified: ancestral (Indian) and recent (European). The reduced diversity and expansion signals of H1a patrilineages imply descent from closely related paternal ancestors who could have settled in the Indian subcontinent, possibly as early as between the eighth and tenth centuries AD. The recent layer of the Bayash paternal pool is dominated by a specific subset of E1b1b1a lineages that are not found in the Balkan majority populations. At least two private mutational events occurred in the Bayash during their migrations from the southern Balkans toward Romania. Additional admixture, evident in the low frequencies of typical European haplogroups, J2, R1a, I1, R1b1b2, G, and I2a, took place primarily during the early Bayash settlement in the Balkans and the Romani bondage in Romania. Our results indicate two phenomena in the Bayash and analyzed Roma: a significant preservation of ancestral H1a haplotypes as a result of considerable, but variable level of endogamy and isolation and differential distribution of less frequent, but typical European lineages due to different patterns of the early demographic history in Europe marked by differential admixture and genetic drift.     

Molecular genetic studies of Creutzfeldt-Jakob disease

Genetic study of over 200 cases of Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS), fatal familial insomnia (FFI), and kuru have brought a reliable body of evidence that the familial forms of CJD and all known cases of GSS and FFI are linked to germline mutations in the coding region of the PRNP gene on chromosome 20, either point substitutions or expansion of the number of repeat units. No pathogenic mutations have so far been found in sporadic or infectious forms of CJD, although there are features of genetic predisposition in iatrogenic CJD and kuru. In FFI and familial CJD, clinically and pathologically distinct syndromes that are both linked to the 178^Asp→Asn substitution, phenotypic expression is dependent on a polymorphism at codon 129. Synthetic peptides homologous to several regions of PrP spontaneously form insoluble amyloid fibrils with unique morphological characteristics and polymerization tendencies. Peptides homologous to mutated regions of PrP exhibit enhanced fibrilogenic properties and, if mixed with the wild-type peptide, produce even more abundant and larger fibrous aggregates. A similar process in vivo may lead to amyloid accumulation and disease, and transmission of “baby fibrils” may induce disease in other hosts.     

A study of sodium release in the course of ATP hydrolysis by membrane ATPase

Summary With the aid of sodium-sensitive glass electrodes, changes in sodium ion activity were studied in the course of subsequent additions of components required for ATP hydrolysis provided by Na⁺–K⁺-dependent membrane ATPase. Membrane ATPase was obtained from guinea pig kidney cortex. In the presence of ATP, Mg⁺⁺ and Na⁺ in media, the addition of K⁺ caused an increase in Na⁺ activity. The omission of ATP or its substitution by ADP as well as the addition of Ca⁺⁺ to the media eliminated the above-mentioned increase of Na⁺ activity. Quabain did not affect Na⁺ release caused by the addition of K⁺, although it significantly inhibited ATPase activity of the preparation. The data obtained were considered to be a direct indication of ion exchange during the course of membrane ATPase reaction. This ion-exchange stage of the reaction is not inhibited by ouabain. The ratio of sodium ions released per one inorganic phosphate formed in the course of the reaction was found to be much higher than that established for transporting membranes of intact cells. A possible cause of this difference is discussed.     

Vascular endothelial cells have impaired capacity to present immunodominant, antigenic peptides: a mechanism of cell type-specific immune escape

Vascular endothelial cells (EC) are an exposed target tissue in the course of CTL-mediated alloimmune diseases such as graft-vs-host disease (GVHD) or solid organ transplant rejection. The outcome of an interaction between CTL and target cells is determined by the amount of Ag presented and the costimulatory signals delivered by the target cells. We compared human EC with leukocytes and epithelial cells as targets for peptide-specific, MHC class I-restricted CTL clones. EC were poor targets for immunodominant CTL. Both endogenously processed antigenic proteins and exogenously added antigenic peptides are presented at 50- to 5000-fold lower levels on EC compared with any other target cell analyzed. This quantitative difference fully explained the poor CTL-mediated killing of EC. There was no evidence that lack of costimulation would contribute significantly to this cell type-specific difference in CTL activation. An HLA-A2-specific CTL clone that killed a broad selection of HLA A2-positive target cells equally well, killed EC less efficiently. Our data suggest that EC present a different Ag repertoire compared with other cell types. By this mechanism, these cells may escape an attack by effector CTL, which have been educated by professional APCs and are specific for immunodominant antigenic peptides.     

VAMP-Associated Protein B (VAPB) Promotes Breast Tumor Growth by Modulation of Akt Activity

VAPB (VAMP- associated protein B) is an ER protein that regulates multiple biological functions. Although aberrant expression of VAPB is associated with breast cancer, its function in tumor cells is poorly understood. In this report, we provide evidence that VAPB regulates breast tumor cell proliferation and AKT activation. VAPB protein expression is elevated in primary and metastatic tumor specimens, and VAPB mRNA expression levels correlated negatively with patient survival in two large breast tumor datasets. Overexpression of VAPB in mammary epithelial cells increased cell growth, whereas VAPB knockdown in tumor cells inhibited cell proliferation in vitro and suppressed tumor growth in orthotopic mammary gland allografts. The growth regulation of mammary tumor cells controlled by VAPB appears to be mediated, at least in part, by modulation of AKT activity. Overexpression of VAPB in MCF10A-HER2 cells enhances phosphorylation of AKT. In contrast, knockdown of VAPB in MMTV-Neu tumor cells inhibited pAKT levels. Pharmacological inhibition of AKT significantly reduced three-dimensional spheroid growth induced by VAPB. Collectively, the genetic, functional and mechanistic analyses suggest a role of VAPB in tumor promotion in human breast cancer.     

The Y chromosome as a target for acquired and amplified genetic material in evolution

The special properties of the Y chromosome stem form the fact that it is a non-recombining degenerate derivative of the X chromosome. The absence of homologous recombination between the X and the Y chromosome leads to gradual degeneration of various Y chromosome genes on an evolutionary timescale. The absence of recombination, however, also favors the accumulation of transposable elements on the Y chromosome during its evolution, as seen with both Drosophila and mammalian Y chromosomes. Alongside these processes, the acquisition and amplification of autosomal male benefit genes occur. This review will focus on recent studies that reveal the autosome-acquired genes on the Y chromosome of both Drosophila and humans. The evolution of the acquired and amplified genes on the Y chromosome is also discussed. Molecular and comparative analyses of Y-linked repeats in the Drosophila melanogaster genome demonstrate that there was a period of their degeneration followed by a period of their integration into RNAi silencing, which was beneficial for male fertility. Finally, the function of non-coding RNA produced by amplified Y chromosome genetic elements will be discussed.     

The ways of realization of high specificity and efficiency of enteropeptidase

Comparative substrate analysis of full-length bovine enteropeptidase and trypsin, bovine and human enteropeptidase light chains was performed using model N-terminal dodecapeptides corresponding to wild-type human trypsinogen and pancreatitis-associated mutant trypsinogens K23R and D22G. The substitution of Lys residue by Arg at P1 leads to 2-fold increase in the efficiency of enteropeptidase hydrolysis; the absence of the negatively charged residue at P2 reduces the efficiency of such hydrolysis by two orders of magnitude. The difference in efficiency of peptide chain hydrolysis after Lys/Arg residues by enteropeptidase compared to trypsin is equal to the difference in hydrolysis by serine proteases of different primary specificity of their specific substrates.     

The influence of cytotoxins from Central Asian cobra venom and melittin from bee venom on the thermodynamic properties of phospholipid bilayer

The interaction of cytotoxin Vc1 and Vc5 from Central Asian cobra and melittin from the bee venom with multilayer liposomes prepared from dimiristoylphosphatidylcholine with an addition of phosphatidic acid have been studied by the method of differential scanning calorimetry. Incorporation of Vc1, Vc5 and melittin into the lipid resulted in pronounced changes in the thermodynamic properties of the lipid. Polypeptides studied induced lateral phase separation in the lipid. Interaction between molecules of the toxins and the lipid resulted in the formation of a new lipid phase characterized by a higher melting temperature and lower phase transition enthalpy.