The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform

Alberto Arab - One of the best experts on this subject based on the ideXlab platform.

  • Occurrence of sibling species of Lutzomyia longipalpis (diptera : Psychodidae) in venezuela : First evidence from reproductively isolated sympatric populations
    The American Journal of Tropical Medicine and Hygiene, 1999
    Co-Authors: Margarita Lampo, Dara G. Torgerson, Luis Miguel Marquez, M. Rinaldi, Carmen Zulay García, Alberto Arab
    Abstract:

    The delimitation of cryptic species within the main vector of the American visceral leishmaniasis, Lutzomyia longipalpis, remains a topic of controversy. An analysis of genetic variability based on 8 enzymatic loci revealed fixed differences in 2 diagnostic loci, adenylate kinase (Ak) and hexokinase (Hk), between sympatric and allopatric populations at 4 localities in Venezuela. The absence of heterozygotes for these 2 loci within 1 locality indicates, for the first time, the presence of 2 sympatric reproductively isolated populations or cryptic species within L. longipalpis. Significant differences were also detected between these cryptic species in the allele frequencies of glucose-6-phosphate isomerase (Gpi) and Malate Dehydrogenase, Decarboxylating (Me). One species showed mean heterozygosities that ranged between 6.6% and 6.7%, with 1.6-1.9 alleles detected per locus, while the other had mean heterozygosities that ranged from 4.3% to 6.3%, with 1.3-1.6 alleles per locus. Comparisons of isozyme profiles with published data suggests that 1 species is similar to the L. longipalpis described in Colombian and Brazilian populations, whereas the other has not been previously reported.

  • Ocurrence of sibling species of Lutzomyia longipalpis (Diptera: Psychodidae) in Venezuela. First evidence from reproductively isolated sympatric populations
    1999
    Co-Authors: Margarita Lampo, Dara G. Torgerson, M. Rinaldi, Luis Ma M. Rquez, Carmen Z. Garci´a, Alberto Arab
    Abstract:

    Abstract. The delimitation of cryptic species within the main vector of the American visceral leishmaniasis, Lutzomyia longipalpis, remains a topic of controversy. An analysis of genetic variability based on 8 enzymatic loci revealed fixed differences in 2 diagnostic loci, adenylate kinase (Ak) and hexokinase (Hk), between sympatric and allopatric populations at 4 localities in Venezuela. The absence of heterozygotes for these 2 loci within 1 locality indicates, for the first time, the presence of 2 sympatric reproductively isolated populations or cryptic species within L. longipalpis. Significant differences were also detected between these cryptic species in the allele frequencies of glucose-6-phosphate isomerase (Gpi) and Malate Dehydrogenase, Decarboxylating (Me). One species showed mean heterozygosities that ranged between 6.6 % and 6.7%, with 1.6–1.9 alleles detected per locus, while the other had mean heterozygosities that ranged from 4.3 % to 6.3%, with 1.3–1.6 alleles per locus. Comparisons of isozyme profiles with published data suggests that 1 species is similar to the L. longipalpis described in Colombian and Brazilian populations, whereas the other has not been previously reported. Many investigators have suggested that Lutzomyia longi-palpis (Lutz and Neiva), the main vector of visceral leish-maniasis in America, is composed of a complex of cryptic species. The evidence published has been nevertheless con

David Lloyd - One of the best experts on this subject based on the ideXlab platform.

  • Trichomonas vaginalis requires traces of oxygen and high concentrations of carbon dioxide for optimal growth
    Molecular and Biochemical Parasitology, 1990
    Co-Authors: Timothy A. Paget, David Lloyd
    Abstract:

    Abstract The effects of O 2 and CO 2 on the growth in culture of Trichomonas vaginalis strain C1-NIH were investigated. Growth under pre-purified N 2 in the absence of CO 2 supplementation gave a doubling time of 4.4 h; when traces of O 2 ( μ M) were present, the doubling time was 3.5 h. Organisms grew most rapidly (doubling time 2.3 h) with traces of O 2 ( μ M) and with the CO 2 level controlled at 5 mM. The balance of fermentation products from maltose was greatly influenced by supplied gases. Under strictly anaerobic conditions at 5 mM CO 2 , equimolar glycerol and lactate accounted for more than 95% of the measured products, whereas lower CO 2 increased acetate production. Under microaerobic conditions (O 2 μ M) acetate was the major product when CO 2 was limited to that evolved endogenously; again 5 mM CO 2 favoured glycerol and lactate production. Activities of key enzymes measured in cell-free extracts (pyruvate:ferredoxin oxidoreductase, hydrogenase, glycerol kinase, Malate Dehydrogenase (Decarboxylating) and lactate Dehydrogenase) altered with growth conditions commensurately with observed changes in metabolic flux patterns. These results suggest that T. vaginalis is optimally adapted to conditions it experiences in situ in the vagina (traces of O 2 , high CO 2 ).

E Mertens - One of the best experts on this subject based on the ideXlab platform.

  • Purification and partial characterization of Malate Dehydrogenase (Decarboxylating) from Tritrichomonas foetus hydrogenosomes.
    Parasitology, 1993
    Co-Authors: I Hrdý, E Mertens
    Abstract:

    Malate Dehydrogenase (Decarboxylating) from Tritrichomonas foetus hydrogenosomes was purified close to homogeneity by a combination of differential centrifugation, zwitterionic detergent solubilization, Red-Sepharose chromatography and anion-exchange chromatography. The enzyme with apparent subunit size of 59 kDa and native molecular mass of 308 kDa utilized NAD+ preferentially to NADP+ as a cofactor and required Mn2+ or Mg2+ for its activity. Affinity curves for Malate and coenzymes were hyperbolic. Km for Malate was 100 microM and 458 microM in the presence of NAD+ and NADP+, respectively. Km for NAD+ and for NADP+ in the presence of Malate was 18 microM and 207 microM, respectively. The enzyme is proposed to be a tetramer with a possible physiological role in the maintenance of an appropriate NAD+/NADH ratio in hydrogenosomes.

Lloyd D - One of the best experts on this subject based on the ideXlab platform.

  • Trichomonas vaginalis requires traces of oxygen and high concentrations of carbon dioxide for optimal growth.
    Elsevier, 1990
    Co-Authors: Paget T A, Lloyd D
    Abstract:

    The effects of O2 and CO2 on the growth in culture of Trichomonas vaginalis strain C1-NIH were investigated. Growth under pre-purified N2 in the absence of CO2 supplementation gave a doubling time of 4.4 h; when traces of O2 (less than 0.25 microM) were present, the doubling time was 3.5 h. Organisms grew most rapidly (doubling time 2.3 h) with traces of O2 (less than 0.25 microM) and with the CO2 level controlled at 5 mM. The balance of fermentation products from maltose was greatly influenced by supplied gases. Under strictly anaerobic conditions at 5 mM CO2, equimolar glycerol and lactate accounted for more than 95% of the measured products, whereas lower CO2 increased acetate production. Under microaerobic conditions (O2 less than 0.25 microM) acetate was the major product when CO2 was limited to that evolved endogenously; again 5 mM CO2 favoured glycerol and lactate production. Activities of key enzymes measured in cell-free extracts (pyruvate:ferredoxin oxidoreductase, hydrogenase, glycerol kinase, Malate Dehydrogenase (Decarboxylating) and lactate Dehydrogenase) altered with growth conditions commensurately with observed changes in metabolic flux patterns. These results suggest that T. vaginalis is optimally adapted to conditions it experiences in situ in the vagina (traces of O2, high CO2)

Margarita Lampo - One of the best experts on this subject based on the ideXlab platform.

  • Occurrence of sibling species of Lutzomyia longipalpis (diptera : Psychodidae) in venezuela : First evidence from reproductively isolated sympatric populations
    The American Journal of Tropical Medicine and Hygiene, 1999
    Co-Authors: Margarita Lampo, Dara G. Torgerson, Luis Miguel Marquez, M. Rinaldi, Carmen Zulay García, Alberto Arab
    Abstract:

    The delimitation of cryptic species within the main vector of the American visceral leishmaniasis, Lutzomyia longipalpis, remains a topic of controversy. An analysis of genetic variability based on 8 enzymatic loci revealed fixed differences in 2 diagnostic loci, adenylate kinase (Ak) and hexokinase (Hk), between sympatric and allopatric populations at 4 localities in Venezuela. The absence of heterozygotes for these 2 loci within 1 locality indicates, for the first time, the presence of 2 sympatric reproductively isolated populations or cryptic species within L. longipalpis. Significant differences were also detected between these cryptic species in the allele frequencies of glucose-6-phosphate isomerase (Gpi) and Malate Dehydrogenase, Decarboxylating (Me). One species showed mean heterozygosities that ranged between 6.6% and 6.7%, with 1.6-1.9 alleles detected per locus, while the other had mean heterozygosities that ranged from 4.3% to 6.3%, with 1.3-1.6 alleles per locus. Comparisons of isozyme profiles with published data suggests that 1 species is similar to the L. longipalpis described in Colombian and Brazilian populations, whereas the other has not been previously reported.

  • Ocurrence of sibling species of Lutzomyia longipalpis (Diptera: Psychodidae) in Venezuela. First evidence from reproductively isolated sympatric populations
    1999
    Co-Authors: Margarita Lampo, Dara G. Torgerson, M. Rinaldi, Luis Ma M. Rquez, Carmen Z. Garci´a, Alberto Arab
    Abstract:

    Abstract. The delimitation of cryptic species within the main vector of the American visceral leishmaniasis, Lutzomyia longipalpis, remains a topic of controversy. An analysis of genetic variability based on 8 enzymatic loci revealed fixed differences in 2 diagnostic loci, adenylate kinase (Ak) and hexokinase (Hk), between sympatric and allopatric populations at 4 localities in Venezuela. The absence of heterozygotes for these 2 loci within 1 locality indicates, for the first time, the presence of 2 sympatric reproductively isolated populations or cryptic species within L. longipalpis. Significant differences were also detected between these cryptic species in the allele frequencies of glucose-6-phosphate isomerase (Gpi) and Malate Dehydrogenase, Decarboxylating (Me). One species showed mean heterozygosities that ranged between 6.6 % and 6.7%, with 1.6–1.9 alleles detected per locus, while the other had mean heterozygosities that ranged from 4.3 % to 6.3%, with 1.3–1.6 alleles per locus. Comparisons of isozyme profiles with published data suggests that 1 species is similar to the L. longipalpis described in Colombian and Brazilian populations, whereas the other has not been previously reported. Many investigators have suggested that Lutzomyia longi-palpis (Lutz and Neiva), the main vector of visceral leish-maniasis in America, is composed of a complex of cryptic species. The evidence published has been nevertheless con