Condition and feeding behaviour of subadult burbot (<Emphasis Type="Italic">Lota lota</Emphasis>) in riverine and lacustrine environments

The condition and feeding behaviour of burbot, a widespread potamodromous species in riverine and lacustrine environments, were compared in order to evaluate the importance of both in three artificial systems. Subadult burbot were sampled in three temperate reservoirs in spring, and one of them also in summer and autumn. Standardised abundance and sizes of burbot were comparable between the reservoirs, but the conditions were significantly different. The Clark’s condition coefficient and index of fullness were independent of burbot size and individuals. Feeding behaviour in terms of abundance and composition of consumed food was environment-dependent. The most common prey category was aquatic insect larvae, dominating in the riverine environment. Permanent water invertebrates, microcrustaceans, beetles and crayfish were less common food and eaten more often in the lacustrine environment. Prey-fish were usually the most common species of suitable size. The food analyses demonstrated opportunistic feeding behaviour with selection of prey associated with benthic habitat and suitable size. Burbot is therefore flexible not only in environments utilisation, but also feeding strategy.     

The peptide nucleic acids (PNAs): "high-tech" probes for genetic and molecular cytogenetic investigations

The peptide nucleic acids (PNAs) constitute a remarkable new class of synthetic nucleic acids analogs, in which the sugar phosphate backbone is replaced by repeating N-(2-aminoethyl) glycine units linked by amine bonds and to which the nucleobases are fixed. This structure gives to PNAs the capacity to hybridize with high affinity and specificity to complementary RNA and DNA sequences, and a great resistance to nucleases and proteinases. Originally conceived as ligands for the study of double stranded DNA, the unique physico-chemical properties of PNAs have led to the development of a large variety of research and diagnostic assays, including antigene and antisense therapy and genome mapping. Several sensitive and robust PNA-dependent methods have been designed for modulating polymerase chain reactions, detecting genomic polymorphisms and mutations or capturing nucleic acids. Over the last few years, the use of PNAs has proven its powerful usefulness in cytogenetics for the rapid in situ identification of human chromosomes and the detection of aneuploidies. Recent studies have reported the successful use of chromosome-specific PNA probes on human lymphocytes, amniocytes, spermatozoa as well as on isolated oocytes and blastomeres. Muticolor PNA protocols have been described for the identification of several human chromosomes, indicating that PNAs could become a powerful tool for in situ chromosomal investigation.     

Increased level of cytokines and matrix metalloproteinases in osteoarthritic subchondral bone

OBJECTIVE: The aim of this study was to investigate the expression of several cytokines, matrix metalloproteinases (MMPs), and tissue inhibitor of matrix metalloproteinases (TIMP)-1 in osteoarthritis (OA) and control sera and different joint tissues. METHODS: Serum, synovial fluid, cartilage, synovial and subchondral bone tissues were examined in OA and control subjects. The protein level of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1alpha, IL-8, IL-10 and MMP-2, MMP-3, MMP-9, and TIMP-1 were measured by immunoanalysis. RESULTS: Serum levels of TNF-alpha, MMP-3 and -9 were significantly higher in OA patients than in controls. Conversely, serum IL-10 was decreased in OA patients. CRP was elevated when compared to healthy controls and decreased significantly 6 months after the surgery. In contrast to control samples, OA cartilage and synovium revealed significantly higher MMP-2, -3, -9 and IL-10. IL-1alpha was significantly higher in OA cartilage and IL-8 in OA synovium. Interestingly, MMP-3, -9, TIMP-1 and all tested cytokines were up-regulated in OA subchondral bone. DISCUSSION: This study demonstrates pro-inflammatory condition of OA pathology and supports the idea that vascularized subchondral region may increase the synthesis of cytokines and MMPs leading to degradation of adjacent cartilage.     

Micro-habitat use within a guild of newt larvae (Trituridae) in an Alpine lake

Population and ecological parameters such as numbers of larvae, microhabitat use, niche breadth and niche overlap of three species of syntopic larval newts (Alpine newt Triturus alpestris, Italian crested newt T. carnifex, and common newt T. vulgaris) were studied for two years in a small pond at 1160 m a.s.l. in NE Slovenia. Differences in microhabitat partitioning among larval newts were small. The largest niche breadth was estimated for larval T. alpestris, and the narrowest estimate was for larval T. carnifex in both years. Ecological differences seem to be very small and quite variable among sites and years. It appears that the developmental stage and size of newt larvae are more important in explaining resource partitioning than the characteristics of each species. Because of the absence of potential invertebrate predators and adult newts in the second half of the breeding season, the injuries could only be caused by intra-and interspecific predation attempts.     

One-electron oxidation of beta-amyloid peptide: sequence modulation of reactivity

Amyloid beta peptide (Abeta) is a 39 to 43 amino-acid-long peptide implicated in Alzheimer's disease. One of its mechanisms of toxicity is related to its redox properties. Therefore we studied its one electron oxidation using azide free radicals produced in gamma and pulse radiolysis, and compared the results with those obtained with the reverse sequence Abeta(40-1). HPLC analysis combined with absorption, fluorescence, Raman spectroscopy, and MALDI-TOF MS were used for product identification. Met35 was shown to be the target in Abeta(1-40); oxidation leads to a major compound that is Abeta with methionine sulfoxide. Similarly, oxidation of fragment Abeta(29-40) also leads to methionine sulfoxide. For Abeta(40-1), Met35 is not reactive and Tyr10 is the target of azide radicals. The major products are peptide dimer linked by dityrosine and trimer. The lowering of the one-electron reduction potential of the MetS+/Met couple, which was proposed, is in agreement with our findings. To our knowledge, this is the first time that such a drastic effect of the primary sequence is observed in a small peptide. In addition, it is also the first experimental demonstration of the sensitivity of the one-electron reduction potential of methionine on neighboring groups.     

Determination of PRKAG1 coding sequence and mapping of PRKAG1 and PRKAG2 relatively to porcine back fat thickness QTL

PRKAG1, PRKAG2 and PRKAG3 encode three isoforms of AMP-activated protein kinase gamma chain. A major effect on meat quality and a medium effect on back fat thickness of the RN- mutation in the PRKAG3 gene has previously been reported. We have now mapped PRKAG1 and PRKAG2 at expected locations on SSC5 and SSC18 by analysis of radiation hybrids (IMpRH panel). PRKAG2 has been mapped in a region where no quantitative trait loci (QTL) has been reported. PRKAG1 has been mapped close to (but probably outside) a region containing a QTL influencing fatness traits. We have determined the full coding sequence of PRKAG1. No missense mutation was identified when comparing the coding sequence of one Meishan and one Large White boars. Further work is, however, required to determine if a polymorphism in PRKAG1 could be responsible for a part of the variability observed on fatness traits.     

Exploring Nitrilase Sequence Space for Enantioselective Catalysis

Nitrilases are important in the biosphere as participants in synthesis and degradation pathways for naturally occurring, as well as xenobiotically derived, nitriles. Because of their inherent enantioselectivity, nitrilases are also attractive as mild, selective catalysts for setting chiral centers in fine chemical synthesis. Unfortunately, <20 nitrilases have been reported in the scientific and patent literature, and because of stability or specificity shortcomings, their utility has been largely unrealized. In this study, 137 unique nitrilases, discovered from screening of >600 biotope-specific environmental DNA (eDNA) libraries, were characterized. Using culture-independent means, phylogenetically diverse genomes were captured from entire biotopes, and their genes were expressed heterologously in a common cloning host. Nitrilase genes were targeted in a selection-based expression assay of clonal populations numbering 10⁶ to 10¹⁰ members per eDNA library. A phylogenetic analysis of the novel sequences discovered revealed the presence of at least five major sequence clades within the nitrilase subfamily. Using three nitrile substrates targeted for their potential in chiral pharmaceutical synthesis, the enzymes were characterized for substrate specificity and stereospecificity. A number of important correlations were found between sequence clades and the selective properties of these nitrilases. These enzymes, discovered using a high-throughput, culture-independent method, provide a catalytic toolbox for enantiospecific synthesis of a variety of carboxylic acid derivatives, as well as an intriguing library for evolutionary and structural analyses.     

Structural diversity of Papaver somniferum L. cell surfaces in vitro depending on particular steps of plant regeneration and morphogenetic program

Culture of Papaver somniferum in vitro was used for a characterisation of cell surface structures and mode of cell adhesion and cell separation during cell differentiation and plant regeneration in somatic embryogenesis and shoot organogenesis. In early stages of somatic embryogenesis, cell type-specific and developmentally regulated change of cell morphogenesis was demonstrated. Cell wall of separated embryonic cells were self-covered with external tubular network, whereas morphogenetic co-ordination of adhered cells of somatic proembryos was supported by fine and fibrillar external cell wall continuum of peripheral cells, interconnecting also local sites of cell separation. Such type of cell contacts disappeared during histogenesis, when the protodermis formation took place. Tight cell adhesion of activated cells with polar cell wall thickening, and production of extent mucilage on the periphery were the crucial aspects of meristemoids. Fine amorphous layer covered developing shoot primordia, but we have not observed such comparable external fibrillar network. On the contrary intercellular separation of differentiated cells in regenerated organs, and accepting distinct developmental system of somatic embryogenesis and shoot organogenesis, cell adhesion in early stages and ultrastructural changes associated with tissue disorganisation, and the subsequent reorganisation into either embryos or shoots appear to be regulatory morphogenetical events of plant regeneration in vitro.     

Allozyme diversity in pheasants (<Emphasis Type="Italic">Phasianus</Emphasis> spp.) from breeding stations in Serbia

The pheasant breeds are widely used for restocking of natural populations depleted by hunting. The pheasant population number decline was detected during the 1970s in many hunting areas of Europe. One of its possible reasons might be the loss of adaptability in populations originating from breeding stations, which was caused by inbreeding depression. The aim of this paper was the analysis of genetic variability in pheasant populations from three breeding stations in Vojvodina province (Serbia) by means of allozyme diversity detection. The allozyme variability analysis of pheasants from all three breeding stations revealed polymorphisms at nine loci: Ldh-1, Mor-1, Mor-2, Es-1, Mod-2, Pgd, Gpi-2, Odh, and Sod. The analysis of individuals from three different breeding stations showed mean values of observed heterozygosity of H _o=0.137, polymorphism P _95%=30%, and H/P ratio H/P=0.430, which indicate a normal level of genetic variability for bird populations. Comparative analysis of three pheasant populations showed a high level of interpopulation differentiation.