Antonio Blanco

Effect of temperature upon catalytic properties of lactate dehydrogenase isoenzymes from a poikilotherm

Lactate dehydrogenase isoenzymes A4 and B4 (l-lactate:NAD+ oxidoreductase, EC 1.1.1.27) have been purified from muscle and heartof the snake Bothrops neuwiedii. Catalytic properties at different temperatures and pH values have been studied compartively with those of the same isoenzymes from beef. Values of Km for ophidian isoenzymes were markedly reduced when the temperature decreased. At low substrate concentrations, the increased enzyme-pyruvate affinity compensates for the lower thermal energy and the reaction rate appears to be independent of temperature. Under the same conditions, the activity of beef isoenzymes was closely related to thermal energy. These findings suggest that lactate dehydrogenases from the poikilotherm are able to function with the same efficiency at all temperatures within the range of habitat and to adjust immediately to thermal changes.

The sexual cycle of male bats: Changes of testicular lactate dehydrogenase isoenzymes

Abstract 1. The sexual activity of bats of the speciesTadarida brasiliensis takes place once a year, at the end of winter. 2. Histological sections of testis from these bats showed spermatogenic activity only during the winter months. 3. Starch gel electrophoretic patterns of testis extracts revealed the apperance of additional lactate dehydrogenase isoenzymes when spermatogenic activity was initiated. 4. The cyclic synthesis of peculiar isoenzymatic forms affords a very useful index to study the factors regulating gene activity.

Restriction fragment-length polymorphism of the mtDNA A+T-Rich region as a genetic marker in Aedes Aegypti (Diptera: Culicidae)

Abstract The usefulness of the control region of mtDNA as a tool for the study of population structure in the mosquito Aedes aegypti (L.) was analyzed. Population samples were taken from several geographic areas of Argentina; one additional sample from the city of San Juan, Puerto Rico, was included for comparison. In individual mosquitoes, the A+T-rich and the COII-COIII regions were amplified by polymerase chain reaction using universal insect primers. Restriction fragment-length polymorphisms were investigated from amplification products. In the A+T region, three amplified fragments of different total length were obtained (of ≈2,500, 2,300, and 2,100 bp). The enzymes Ssp I, Dra I, Pac I, and Apo I produced polymorphic patterns. Including total fragment length as a variable, eight different haplotypes were resolved for Argentinian populations, some presenting a restricted geographic distribution. The coding COII-COIII region revealed very low polymorphism. Although 11 restriction enzymes were employed to analyze this region, only two different haplotypes were found, one of them shared by populations as distant as Buenos Aires and San Juan. We demonstrated that total length and restriction fragment-length polymorphisms within the noncoding A+T-rich region, but not the coding COII-COIII fragment, are informative to discriminate Aedes aegypti populations. Mean FST value (0.48, P < 0.001) indicates an important degree of differentiation among populations. Absence of an isolation by distance pattern was demonstrated.

Enzyme polymorphism in a population of Calomys musculinus (Rodentia, Cricetidae).

NAD-linked lactate, malate, glycerophosphate, alcohol and nonspecific dehydrogenases, aspartate aminotransferases, and soluble esterases from extracts of tissues of individuals from a wild population of Calomys musculinus (Rodentia, Cricetidae) have been analyzed by means of starch gel electrophoresis and specific staining. Allelic frequencies and heterozygosity have been determined. Mendelian inheritance of some of the variants detected was confirmed by breeding experiments. Ten out of fifteen (66.6%) of the genetic loci investigated presented polymorphism. Mean heterozygosity per locus was very high (H=0.2014, se 0.046).

Identification of Trypanosoma cruzi Zymodemes by Kinetoplast DNA Probes

ABSTRACT Analysis of zymograms of extracts of Trypanosoma cruzi isolated from different hosts in Argentina allowed characterization of 12 zymodemes or “isozymic strains,” only six of which were found in human patients. Two of these six zymodemes (Z1 and Z12) were widely distributed and found in more than 80% of human patients. These two “major natural clones” differed significantly in pathogenic activity. Because the groupings obtained by studying enzymes and kinetoplast DNA (kDNA) were similar, it is possible to identify the zymodeme by analyzing kDNA. A 290‐bp fragment was amplified by PCR using primers for the sequences flanking the hypervariable regions of kDNA minicircles. Labeled probes for this fragment, prepared from Z1 and Z12 reference stocks, hybridized specifically with PCR‐amplified kDNA from parasite stocks, allowing identification of zymodemes.

Expression of lactate dehydrogenase isozyme X in haploid cells of pigeon testis.

SummaryElectrophoretic patterns of lactate dehydrogenase (EC 1.1.1.27) from adult testes show the existence of three different phenotypes for the isozyme X or C4 in populations of racing homer pigeons. These phenotypes are the expression of two different alleles at the Ldh c locus. Analysis of electrophoretic patterns of lactate dehydrogenase from lysates of mature spermatozoa isolated from pigeons heterozygous at the Ldh c locus indicates that the two different alleles are expressed in haploid cells. It is concluded that transcription of the gene coding for isozyme X must occur only in pre-meiotic cells.

Temporal variations of allele frequencies in the eared dove (Zenaida auriculata)

In 1975 we started a study on enzyme polymorphism in the eared dove ( Z e n a i d a aur icu la ta ) , a widely distributed species in South America. The eared dove has become a serious economic problem, for it has prospered with the development of agriculture in Argentina and other South American countries, and large breeding colonies have recently developed in central Argentina as a consequence of agricultural expansion in previously forested areas (Murton et al., 1974). In a previous paper (Cornejo de Caminos et al., 1977), we described polymorphism in three enzymes (one aminotransferase and two esterases) from liver extracts of the dove and reported distribution of phenotypes and allele frequencies in a population. From 1975 to 1979 we have obtained population samples from the same colony and studied the same enzymes. The data collected allowed a comparative analysis and showed significant variations in allele frequencies between samples.