Flavivirus isolations from mosquitoes collected from Saibai Island in the Torres Strait, Australia, during an incursion of Japanese encephalitis virus

Adult mosquitoes (Diptera: Culicidae) were collected in January and February 2000 from Saibai Island in the Torres Strait of northern Australia, and processed for arbovirus isolation during a period of Japanese encephalitis (JE) virus activity on nearby Badu Island. A total of 84 210 mosquitoes were processed for virus isolation, yielding six flavivirus isolates. Viruses obtained were single isolates of JE and Kokobera (KOK) and four of Kunjin (KUN). All virus isolates were from members of the Culex sitiens Weidemann subgroup, which comprised 53.1% of mosquitoes processed. Nucleotide sequencing and phylogenetic analysis of the pre-membrane region of the genome of JE isolate TS5313 indicated that it was closely related to other isolates from a sentinel pig and a pool of Cx. gelidus Theobald from Badu Island during the same period. Also molecular analyses of part of the envelope gene of KUN virus isolates showed that they were closely related to other KUN virus strains from Cape York Peninsula. The results indicate that flaviviruses are dynamic in the area, and suggest patterns of movement south from New Guinea and north from the Australian mainland.     

Making more heart muscle

Postnatally, heart muscle cells almost completely lose their ability to divide, which makes their loss after trauma irreversible. Potential repair by cell grafting or mobilizing endogenous cells is of particular interest for possible treatments for heart disease, where the poor capacity for cardiomyocyte proliferation probably contributes to the irreversibility of heart failure. Knowledge of the molecular mechanisms that underly formation of heart muscle cells might provide opportunities to repair the diseased heart by induction of (trans) differentiation of endogenous or exogenous cells into heart muscle cells. We briefly review the molecular mechanisms involved in early development of the linear heart tube by differentiation of mesodermal cells into heart muscle cells. Because the initial heart tube does not comprise all the cardiac compartments present in the adult heart, heart muscle cells are added to the distal borders of the tube and within the tube. At both distal borders, mesodermal cell are recruited into the cardiac lineage and, within the heart tube, muscular septa are formed. In this review, the relative late additions of heart muscle cells to the linear heart tube are described and the potential underlying molecular mechanisms are discussed.     

Caffeine sensitivity of native RyR channels from normal and malignant hyperthermic pigs: effects of a DHPR II-III loop peptide

Enhanced sensitivity to caffeine is part of the standard tests for susceptibility to malignant hyperthermia (MH) in humans and pigs. The caffeine sensitivity of skeletal muscle contraction and Ca²⁺ release from the sarcoplasmic reticulum is enhanced, but surprisingly, the caffeine sensitivity of purified porcine ryanodine receptor Ca²⁺-release channels (RyRs) is not affected by the MH mutation (Arg⁶¹⁵Cys). In contrast, we show here that native malignant hyperthermic pig RyRs (incorporated into lipid bilayers with RyR-associated lipids and proteins) were activated by caffeine at 100- to 1,000-fold lower concentrations than native normal pig RyRs. In addition, the results show that the mutant ryanodine receptor channels were less sensitive to high-affinity activation by a peptide (C_S) that corresponds to a part of the II–III loop of the skeletal dihydropyridine receptor (DHPR). Furthermore, subactivating concentrations of peptide C_S enhanced the response of normal pig and rabbit RyRs to caffeine. In contrast, the caffeine sensitivity of MH RyRs was not enhanced by the peptide. These novel results showed that in MH-susceptible pig muscles 1) the caffeine sensitivity of native RyRs was enhanced, 2) the sensitivity of RyRs to a skeletal II–III loop peptide was depressed, and 3) an interaction between the caffeine and peptide C_S activation mechanisms seen in normal RyRs was lost. calcium ion homeostasis; excitation-contraction coupling; ryanodine receptor polymorphisms; muscle contraction     

Antistaphylococcal activity of the complex of natural cytokines

The in vitro study of the action of the complex of natural cytokines (CNC), or preparation Superlymph, on different microbial test strains (Staphylococcus aureus, Escherichia coli, yeast-like fungi of the genus Candida) was carried out. CNC suppressed the growth of S. aureus test culture, depending on the concentration of the preparation. The inhibiting effect was observed in the presence of Ca and Mg bivalent cations in the medium. Under the chosen conditions of the experiment CNC did not inhibit the growth of E. coli test cultures, as well as test cultures of yeast-like fungi of the genus Candida. In addition to its antibacterial effect, Superlymph also produced some effect on the release of cathepsin G, the lysosomal enzyme of human leukocyte granules.     

Influence of the activation of the immune system cells on the parameters of lipid metabolism in macrophages

The influence of tumor necrosis factor a (TNF-alpha) and media, conditioned by activated macrophages and lymphocytes and containing a complex of biologically active compounds (including cytokines), on the parameters of lipid metabolism in macrophages was studied. The addition of recombinant TNF-alpha and immunocompetent cell-conditioned media to mouse peritoneal macrophages culture stimulated labelled oleate incorporation into cholesterol esters and triglycerides, as well as labelled glycerine incorporation into cholesterol esters, but inhibited labelled cholesterol incorporation into cholesterol esters. One of the mechanisms of the influence of activated immunocompetent cells on cholesterol metabolism in macrophages was, supposedly, the stimulation of sphigmomyelinase activity by a complex of anti-inflammatory cytokines produced by these cells on their activation.     

Seasonal dynamics of infecting ability of the flea Citellophilus tesquorum altaicus in the Tuva natural focus of the plague

The infecting ability of the fleas Citellophilus tesquorum altaicus loff, 1936, the main plague vectors in the Tuva natural focus, was experimentally studied in different periods of the epizootic season. Seasonal dynamics in the efficiency of infecting the long-tailed Siberian souslik with the plague causative agent through flea bites was noticed. Seasonal differences in infectivity of the "blocked" flea bites are revealed. An increase of infected experimental animals with a generalization of infection process in the period of epizooty activation in the natural focus was observed. A resistance of the long-tailed Siberian souslik to the plague agent infection through flea bites in the spring season was registered.     

Mapping 245 SSR markers on the <Emphasis Type="Italic">Vitis vinifera</Emphasis> genome: a tool for grape genetics

The aim of the present work was to develop a microsatellite marker-based map of the Vitis vinifera genome (n=19), useful for genetic studies in this perennial heterozygous species, as SSR markers are highly transferable co-dominant markers. A total of 346 primer pairs were tested on the two parents (Syrah and Grenache) of a full sib population of 96 individuals (S × G population), successfully amplifying 310 markers. Of these, 88.4% markers were heterozygous for at least one of the two parents. A total of 292 primer pairs were then tested on Riesling, the parent of the RS₁ population derived from selfing (96 individuals), successfully amplifying 299 markers among which 207 (62.9%) were heterozygous. Only 6.7% of the markers were homozygous in all three genotypes, stressing the interest of such markers in grape genetics. Four maps were constructed based on the segregation of 245 SSR markers in the two populations. The Syrah map was constructed from the segregations of 177 markers that could be ordered into 19 linkage groups (total length 1,172.2 cM). The Grenache map was constructed with the segregations of 178 markers that could be ordered into 18 linkage groups (total length 1,360.6 cM). The consensus S × G map was constructed with the segregations of 220 markers that were ordered into 19 linkage groups (total length 1,406.1 cM). One hundred and eleven markers were scored on the RS₁ population, among them 27 that were not mapped using the S × G map. Out of these 111 markers, 110 allowed to us to construct a map of a total length of 1,191.7 cM. Using these four maps, the genome length of V. vinifera was estimated to be around 2,200 cM. The present work allowed us to map 123 new SSR markers on the V. vinifera genome that had not been ordered in a previous SSR-based map (Riaz et al. 2004), representing an average of 6.5 new markers per linkage group. Any new SSR marker mapped is of great potential usefulness for many applications such as the transfer of well-scattered markers to other maps for QTL detection, the use of markers in specific regions for the fine mapping of genes/QTL, or for the choice of markers for MAS.