Ixodes (Pholeoixodes) hexagonus, an efficient vector of Borrelia burgdorferi in the laboratory

Borrelia burgdorferi Johnson et al. was first isolated from the midgut of Ixodes dammini Spielman et al. in the U.S.A. and from the midgut of I.ricinus (L.) in Europe. I.ricinus was considered to be the only tick vector of this borrelia, in Europe, until I.hexagonus Leach, the hedgehog tick, was found to harbour spirochaetes. This paper reports an evaluation of the vector competence of I.hexagonus for the spirochaete B.burgdorferi. Transovarial and trans-stadial survival were demonstrated and the spirochaete was transmitted to laboratory mice via the bites of trans-stadially infected I.hexagonus females.     

Nitroarginine,an inhibitor of nitric oxide synthetase,attenuates ammonia toxicity and ammonia-induced alterations in brain metabolism

We have proposed that acute ammonia toxicity is mediated by activation of the N-methyl-D-aspartate type of glutamate receptors. MK-801, a selective antagonist of these receptors, prevents death of animals induced by acute ammonia intoxication as well as ammonia-induced depletion of ATP. It seems therefore that, following activation of the N-methyl-D-aspartate receptors, the subsequent events in ammonia toxicity should be similar to those involved in glutamate neurotoxicity. As it has been shown that inhibitors of nitric oxide synthetase such as nitroargnine prevent glutamate toxicity, we have tested whether nitroarginine prevents ammonia toxicity and ammonia-induced alterations in brain energy and ammonia metabolites. It is shown that nitroarginine prevents partially (50%), but significantly death of mice induced by acute ammonia intoxication. Nitroarginine also prevents partially ammonia-induced depletion of brain ATP. It also prevents completely the rise in glucose and pyruvate and partially that in lactate. Injection of nitroarginine alone, in the absence of ammonia, induces a remarkable accumulation of glutamine and a decrease in glutamate. The results reported indicate that nitroarginine attenuates acute ammonia toxicity and ammonia-induced alterations in brain energy metabolites. The effects of MK-801 and of nitroarginine are different, suggesting that ammonia can induce nitric oxide synthetase by mechanisms other than activation of N-methyl-D-aspartate receptors.     

RNA composition of Junin virus.

Junin virus grown in BHK-21 cells was labeled with [3H]uridine and highly purified by differential and isopycnic centrifugation. The RNAs extracted with phenol and analyzed by polyacrylamide gel electrophoresis were shown to be composed of four large species (33, 28, and 18S) and three small ones (4, 5, and 5.5S). This pattern was similar to ones already reported for other arenaviruses. However, there was a striking difference when the virus labeling was performed in the presence of actinomycin D. Labeling of viral rRNA was as much as 60% of the levels obtained in the absence of the drug under conditions in which cellular rRNA's were inhibited by 95% or more.     

DNA gyrase inhibitors block development of Bacillus subtilis bacteriophage SP01

SP01 development was inhibited by nalidixic acid and novobiocin in the sensitive host Bacillus subtilis 168M. Inhibition by novobiocin was prevented by a Novr mutation in the cellular DNA gyrase gene. Nalidixic acid inhibition persisted in hosts carrying a Nalr gyrase, but could be overcome by phage mutation. We conclude that SP01 requires for its development subunit B of the host DNA gyrase, but replaces or modifies subunit A.     

Characterization of a group I intron in the nuclera rDNA differentiatingPhialophora gregata f. sp.adzukicola fromP. gregata f. sp.sojae

An insertion sequence was detected near the 3′ end of the nuclear small subunit rDNA in isolates ofPhialophora gregata f. sp.adzukicola, the causal agent of the brown stem rot disease of adzuki bean. This insertion sequence was absent in isolates ofP. gregata, f. sp.sojae which causes brown stem rot of soybean. The insertion sequence is 304 bp long and contains all the characteristics of group I introns. These characteristics include, the four conserved sequence elements (P, Q, R, and S), a U at the 5′ splice site of the exon, a G at the 3′ splice site of the intron, a putative internal guiding sequences; the sequence also fits a secondary structure model for group I introns. Similar to most group I introns found in nuclear small subunit rDNA, the intron was located in a highly conserved region and is devoid of long open reading frames. This intron provides a convenient marker for use in conventional PCR to separateP. gregata f. sp.adzukicola fromP. gregata f. sp.sojae.     

Mortality and survival of African Penguins Spheniscus demersusinvolved in the Apollo Seaoil spill: an evaluation of rehabilitation efforts

The bulk ore carrier Apollo Sea sank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersus were oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay.     

Regulation of the synthesis of unsaturated fatty acids by growth temperature in Bacillus subtilis

Bacillus subtilis synthesizes, almost exclusively, saturated fatty acids, when grown at 37° C. When cultures were transferred from 37° C to 20° C, a chloramphenicol- and rifampicin-sensitive synthesis of a C-16 unsaturated fatty acid was observed. Synthesis of this compound reached a plateau after 5 h at 20° C, reaching levels of 20% of the total fatty acid content. [¹⁴C]-labelled fatty acids attached as thioesters to acyl-carriers compounds, such as coenzyme A (CoA) or acyl-carrier protein (ACP) synthesized de novo by glycerol-requiring auxotrophs deprived of glycerol to arrest phospholipid synthesis, could not be desaturated at 20° C. Desaturation of these fatty acids was readily observed when glycerol was restored to the cultures allowing resumption of transfer of acyl-moieties from acyl-thioesters to phospholipid. It was also observed that depletion of the pools of CoA and ACP by starvation of pantothenate auxotrophs had no effect on the observed synthesis of unsaturated fatty acid at 20° C. The overall results indicate that synthesis of unsaturated fatty acids in B. subtilis is a cold-inducible process and that phospholipids are obligate intermediates in this fatty acid desaturation pathway.