Temperature and photoperiod effects on dormancy status and life cycle parameters in Aedes albopictus and Aedes aegypti from subtropical Argentina.

Aedes albopictus (Diptera: Culicidae) distribution is bounded to a subtropical area in Argentina, while Aedes aegypti (Diptera: Culicidae) covers both temperate and subtropical regions. We assessed thermal and photoperiod conditions on dormancy status, development time and mortality for these species from subtropical Argentina. Short days (8 light : 16 dark) significantly increased larval development time for both species, an effect previously linked to diapause incidence. Aedes albopictus showed higher mortality than Ae. aegypti at 16 °C under long day treatments (16 light : 8 dark), which could indicate a lower tolerance to a sudden temperature decrease during the summer season. Aedes albopictus showed a slightly higher percentage of dormant eggs from females exposed to a short day, relative to previous research in Brazilian populations. Since we employed more hours of darkness, this could suggest a relationship between day-length and dormancy intensity. Interestingly, local Ae. aegypti presented dormancy similar to Ae. albopictus, in accordance with temperate populations. The minimum dormancy in Ae. albopictus would not be sufficient to extend its bounded distribution. We believe that these findings represent a novel contribution to current knowledge about the ecophysiology of Ae. albopictus and Ae. aegypti, two species with great epidemiological relevance in this subtropical region.

Direct molecular identification of Trypanosoma cruzi discrete typing units in domestic and peridomestic Triatoma infestans and Triatoma sordida from the Argentine Chaco.

We assessed the distribution of Trypanosoma cruzi Discrete Typing Units (DTUs) in domestic and peridomestic Triatoma infestans and Triatoma sordida specimens collected in a well-defined rural area in Pampa del Indio, northeastern Argentina. Microscopically-positive bugs were randomly selected with a multi-level sampling design, and DTUs were identified using direct PCR strategies. TcVI predominated in 61% of 69 T. infestans and in 56% of 9 T. sordida. TcV was the secondary DTU in T. infestans (16%) and was found in 1 T. sordida specimen (11%). Three T. sordida (33%) were found infected with TcI, a DTU also identified in local Didelphis albiventris opossums. Mixed DTU infections occurred rarely (5%) and were detected both directly from the bugs' rectal ampoule and parasite cultures. The identified DTUs and bug collection sites of T. infestans were significantly associated. Bugs infected with TcV were almost exclusively captured in domiciles whereas those with TcVI were found similarly in domiciles and peridomiciles. All mixed infections occurred in domiciles. TcV-infected bugs fed more often on humans than on dogs, whereas TcVI-infected bugs showed the reverse pattern. T. sordida is a probable sylvatic vector of TcI linked to D. albiventris, and could represent a secondary vector of TcVI and TcV in the domestic/peridomestic cycle.

Partial purification of mitochondrial ribosomes from broad bean and identification of proteins encoded by the mitochondrial genome.

An approach towards the identification at the protein level of the ribosomal proteins encoded by the mitochondrial genome of broad bean (Vicia faba) has been developed. After Triton X-100 treatment of isolated mitochondria, a fraction enriched in mitochondrial ribosomes was obtained by successive centrifugation, first onto a sucrose cushion, and then in a sucrose gradient. Mitochondrial translation products were labelled in isolated mitochondria with [35S]methionine and added to the enriched mitochondrial ribosomal proteins before separation by two-dimensional gel electrophoresis. Six spots, identified both by Coomassie blue staining and autoradiography, were analysed by protein micro-sequencing. Two of these were shown to correspond to ribosomal proteins S10 and S12. We conclude that these two proteins are encoded by the mitochondrial genome of broad bean and that the method described here can be used to identify other proteins encoded by the mitochondrial genome.

Alpha subunit of mitochondrial F1-ATPase from the fission yeast. Deduced sequence of the wild type and identification of a mutation that alters apparent negative cooperativity.

The nuclear gene atp1 encoding the mitochondrial ATP synthase alpha subunit of the fission yeast Schizosaccharomyces pombe was sequenced. It contains a 1,608-base pair-long open reading frame interrupted by two introns of 175 and 269 base pairs, located near the 5'-end of the gene. The initiation site of transcription AAAC was located 60 nucleotides upstream of the translation initiation codon. The deduced polypeptide sequence contains a 27-amino acid residue presequence, presumably involved in mitochondrial targeting, preceding a mature protein of 509 amino acid residues. The atp1 alleles from mutant A2313 (Bouty, M., and Goffeau, A. (1982) Eur. J. Biochem. 125, 471-477) and its related phenotypic revertant R351 (Falson, P., Di Pietro, A., Darbouret, D., Jault, J. M., Gautheron, D. C., Boutry, M., and Goffeau, A. (1987) Biochem. Biophys. Res. Commun. 148, 1182-1188) were also cloned and sequenced. A single nonsense mutation CAA-TAA (Gln173-stop) in mutant A2313 became a missense mutation TAA-TTA (stop-Leucine) in revertant R351. Glutamine 173 is located in the first putative element of the nucleotide binding site. Its substitution by a leucine residue appears responsible for the lower enzyme affinity toward ADP and for the loss of cooperativity of F1-ATPase activity.

The primary structure of iron superoxide dismutase from Escherichia coli.

The complete amino acid sequence of iron superoxide from Escherichia coli has been determined. The sequence was deduced from analysis of peptides obtained after cleavage of the carboxymethylated apoenzyme with trypsin. Stapholococcus aureus protease or CNBr. The polypeptide chain is made up of 192 residues and is easily aligned with the other known amino acid sequences of iron and manganese superoxide dismutases from various sources. The iron superoxide dismutase from E. coli shows a significantly higher homology with the iron enzyme from a different organism than with the manganese isoenzyme from E. coli.