Leiurus quinquestriatus venom inhibits different kinds of Ca2+-dependent K+ channels

A minor protein component of Leiurus quinquestriatus venom has been reported to inhibit selectively the apamin-insensitive Ca2+-dependent K+ channels of mammalian skeletal muscle (Miller, C., Moczydlowski, E., Latorre, R. and Phillips, M. (1985) Nature 313, 316-318). We report the effect of the venom on both the apamin-insensitive channels of the human erythrocyte, the Ehrlich cell and the rat thymocyte and the apamin-sensitive channel of the guinea pig hepatocyte. The venom inhibited Ca2+-dependent K+ transport in all the cases with a Ki value within the range of 1 to 10 micrograms/ml, similar to that reported previously in muscle. Valinomycin-induced K+ transport was also antagonized by the venom but its sensitivity was about 1/10 as much as that of the Ca2+-dependent K+ channel.     

Quantitation and characterization of tau factor in porcine tissues

Using a monospecific antibody against brain tau factor purified by affinity chromatography, we have studied the distribution of tau factor or related polypeptides in different cells. The presence of tau in all cell types tested was demonstrated by a radioimmunoassay. Tau factor-related proteins were found in liver, spleen, pancreas, kidney and lung, although at much lower levels than that found in neural cells. In all cases, they copolymerized with tubulin and were heat-resistant. When the distribution of tau factor-related proteins was studied by Western blotting, tau factor antiserum reacted against peptides with an electrophoretic mobility that was similar to those of brain tau factor peptides. Immunofluorescence studies have also been performed with the same antibody to determine the distribution of tau factor-related peptides in PK15 cells. Our results indicated that these peptides were associated to the microtubule network.     

Maintenance of aPaecilomyces variotii culture in the frozen and Freeze-dried state and in distilled water

The highest number of viable.elements ofPaecilomyces variotii, forming colonies after a 1-year maintenance, was detected in frozen sample. Decreased viability of the frozen culture and culture maintained in distilled water was usually statistically significant after 1 year and decreased further with increasing age of the culture used for sample preparation. Freeze-drying also significantly decreased the strain viability, depending on culture age. In the freeze-dried culture stored in a refrigerator the relative number of viable elements was substantially higher than after storage at room temperature. After a 3-year storage of freeze-dried P.variotii in a refrigerator 14-44% of culture elements survived, as compared with the number detected immediately after freeze-drying.     

Benzothiazolium salts—relationships between their structure,toxicity and effect on the plastid system ofEuglena gracilis

The effects of 41 benzothiazolium salts on Euglena gracilis were characterized with regard to the influence on growth and on chlorophyll synthesis, and to their ability to induce permanent loss of chloroplasts. Some salts induced white mutants of E. gracilis (the first benzothiazole derivatives with this activity). The relationship between the biological effect and chemical structure was confirmed and expressed quantitatively by means of Free - Wilson and Fujita - Ban analysis.     

The adhesin structures involved in the adherence of group B streptococci to human vaginal cells

The adherence of group B streptococci (GBS) of serotypes Ia, II and III to human vaginal cells was studied in vitro. The adherence was not dependent on the viability of bacteria; killing of GBS by UV irradiation or glutaraldehyde treatment did not inhibit the adherence. Killing of GBS by heating to 56 degrees C for 1 h led to a pronounced decrease of adherence, demonstrating the thermosensitivity of the GBS structures involved. The protein nature of these structures was proved by a significant reduction of adherence after pretreatment of GBS with trypsin or pepsin. Pretreatment of GBS with sialidase had no influence on the adherence. Such a pretreatment of vaginal cells caused an increase of adherence showing that the receptors on epithelial cells may be partly masked by sialic acid.     

The hair of the common hare (Lepus europaeus Pall.) and of the common vole (Microtus arvalis Pall.) as indicator of the environmental pollution

We made the INAA of hair of the common hare (Lepus europaeus Pall.) and of the common vole (Microtus arvalis Pall.) living in the emission zones. Both the hare and the vole are almost exclusively herbivores; they consume relatively large amounts of contaminated food and mirror reliably the contamination degree of the respective ecosystem. The use of free-living animals for the control of the environmental quality may complete effectively the information obtained by examination of habitants. Though the free-living animals lead a rather different way of existence it has been found that the analyses of their hair correlate very well with the analyses of human hair. It may be expected that the changes of concentrations of heavy metals will manifest themselves earlier in animals than in men, because the animals are strictly tied to the local food sources. The hair samples of hares contained increased concentrations of Sm, La, Au, As, Se, Cr, Sc, Fe, Ce, Th and Co. The hair of voles showed increased concentrations of Sm, La, Zn, As, Se, Cr, Sc, Fe, Sb, Ce, Cs and Co. A conspicuous trend towards the cumulation in hair was observed in the following elements: As, Se, Sc and Fe. The increase of their concentrations in the hair of animals from the emission regions amounted as such as to 10(3)%.     

Arbovirological survey in Silica plateau area, Roznava District, Czechoslovakia

The serosurveys conducted in the Silica plateau area of the Slovak karst region revealed the presence of specific neutralizing antibody against tick-borne encephalitis (TBE) virus in 18% of local inhabitants (33 examined, mostly goats and sheep farmers), 54% of goats (26 examined), 18% of sheep (120 examined) and 13% of cattle (60 examined), against Lipovník (LIP) virus in 30% of inhabitants, 88% of goats, 55% of sheep and 45% of cattle, and against Bhanja (BHA) virus in 27% of inhabitants, 46% of goats, 29% of sheep and 23% of cattle. The results of hemagglutination-inhibition tests with TBE and BHA antigens were analogous. A detailed analysis of these serologic data points to a recent enhancement of the circulation of LIP and BHA viruses and to a very low TBE virus activity in this natural focus of arboviral infections. The immunological surveys of the 32 former "Roznava disease" patients, conducted 25 years after an extensive epidemic of a TBE virus infection that originated in Roznava in 1951, revealed the presence of neutralizing (and also hemagglutination-inhibiting) antibodies against TBE virus in as many as 78% of cases. Antibodies against LIP and BHA viruses were also detectable in the sera of 16% and 9%, respectively, of these individuals. Populations of the ectoparasites examined for the presence of arbovirus comprised 231 Ixodes ricinus, 806 Dermacentor marginatus and 204 Haemaphysalis punctata ticks and 117 specimens of the louse-flies Melophagus ovinus. Two strains of arbivirus that were antigenically related to Lipovník and Tribec viruses belonging to a group of Kemerovo viruses were isolated from male and female I. ricinus ticks collected from cattle.     

Solid-state conformation of some basic sequential polypeptides

We have studied the structure of solid films obtained by x-ray diffraction, from several basic polypeptides with a defined sequence. The alterating polypeptides poly(Ala-Lys), poly(Leu-Lys), poly(Val-Lys), and poly(Arg-Leu) all show a cross-β-structure in which layers of hydrophilic side chains alternate with layers containing hydrophobic side chains. The other polypeptides studied are not in the β-conformation and appear to be in the α-helical conformation. The helices obtained from poly(Lys-Ala-Ala) and poly(Lys-Ala-Ala-Lys) appear to be packed in an unusual fashion, which favors interaction between alanine side chains. Such behavior is not found in poly(Lys-Leu-Ala).     

Microhabitat utilization by two leptodactylid frogs in the Andes of central Chile

Summary Some basic parameters of the life history of Alsodes montanus and Alsodes tumultuosus (Anura-Leptodactylidae), were studied from 1977 to 1980 by periodic field observations at Farellones and La Parva (33–34° south lat.; 2,700–3,000 m above sea level). Special attention was paid to strategies of resource partitioning in relation to gross features of the environment. The latter was unstable with a relative short period favorable for activity of the animals. Physical environmental differences between the first and second season of this study, resulted in a decrease in total number of active adults, a reduction in the duration of larval activity and a shift in microhabitat preferences of larvae.During the favorable season, October to May, adults of both species showed spatial and temporal segregation, related to different physical features of the environment; larvae did not show temporal segregation. Larvae of both species were found in seven different microhabitats; only in one of these did they show significant difference in microhabitat preference, A. tumultuosus was found more often in crevices. Microhabitat dimensions were more important than time and food resources in the separation of the niches of the two species. The segregation of niche dimensions, microhabitat, diel and annual activity and food were not complementary.Coexistence was therefore observed with the species tending to use different resources. When the same resource was used, it was not limiting.