15 research outputs found

    Genetic differentiation estimated by isozymic analysis of Africanized honeybee populations from Brazil and from Central America

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    Adult Apis mellifera workers were electrophoretically examined in at least 7 enzyme loci. Five loci were found to exhibit polymorphism (Est-1, Est-3, PGM-1, HK-1 and MDH-1) in the Africanized bee populations from Brazil and from Central America (Costa Rica and Honduras). Genetic variation was not observed for Est-1 and HK-1 in the bee samples from Italy and Germany, and for PGM-1 in the Italian bee sample. Genotypic frequencies at the MDH-1 and HK-1 loci in the Honduras sample are in disagreement with that expected for Hardy-Weinberg equilibrium, suggesting an incipient process of mixture between pre-existing European bees in this country and the Africanized swarms that came from South America. Racial admixture estimates based on MDH-1 data indicate that the Africanization level of Central American honeybees is less than for bees from Southeast and Northern Brazil

    Association between isoenzymatic phenotypes and resistance to the fungus Microcyclus ulei P. Henn. (v. Arx.) in rubber tree clones.

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    Made available in DSpace on 2012-12-06T01:01:28Z (GMT). No. of bitstreams: 1 SP4669.pdf: 435219 bytes, checksum: 0b816e669a47c2a60ecf2fd7fc893102 (MD5) Previous issue date: 1999-02-26199

    Genetic characterization of a new Apis mellifera esterase

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    A new esterase, denoted esterase-1a (Est-1a), was first identified by starch gel electrophoresis of abdomen extracts from adult drones of Apis mellifera. This enzyme was developed only with 4-methylumbelliferyl esters and its inhibition properties suggest that it is an arylesterase. It does not contain reactive sulfhydryl groups and has a monomeric structure. A genetic variant (Est-1a92) was detected at an average frequency of 4.2% in drones collected from five apiaries. Genetic linkage studies showed no close linkage between the Est-1a locus and the genetic markers Est-6, Mdh-1 and Hk-1. Esterase-1 a activity was observed in the reproductive and digestive tracts of sexually mature drones, queens and egg-laying workers, suggesting its association with sexual maturation. In view of its presence in the egg and its restricted localization in the middle portion of the digestive tract (midgut), this enzyme may play a proteolytic role in early embryonic development

    <FONT FACE=Symbol>k</FONT>-Casein, <FONT FACE=Symbol>b</FONT>-lactoglobulin and growth hormone allele frequencies and genetic distances in Nelore, Gyr, GuzerĂĄ, Caracu, Charolais, Canchim and Santa Gertrudis cattle

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    The genotypes for k-casein (<FONT FACE="Symbol">k</FONT>-CN), <FONT FACE="Symbol">b</FONT>-lactoglobulin (<FONT FACE="Symbol">b</FONT>-LG) and growth hormone (GH) were determined by polymerase chain reaction (PCR) and restriction enzyme digestion in seven breeds of cattle (Nelore, Gyr, GuzerĂĄ, Caracu, Charolais, Canchim and Santa Gertrudis). <FONT FACE="Symbol">k</FONT>-Casein had two alleles with the A allele occurring at a higher frequency in Bos indicus breeds (0.93, 0.92 and 0.91% for Gyr, GuzerĂĄ and Nelore, respectively). The <FONT FACE="Symbol">b</FONT>-lactoglobulin locus had two alleles in all of the breeds. European breeds had a higher frequency of the <FONT FACE="Symbol">b</FONT>-LG A allele than Zebu breeds. The GH locus had two alleles (L and V) in Bos taurus and was monomorphic (L allele only) in all of the Bos indicus breeds evaluated. The highest frequency for the V allele was observed in Charolais cattle. The markers used revealed a considerable similarity among breeds, with two main groups being discernible. One group consisted of Zebu and Santa Gertrudis breeds and the other consisted of European and Canchim breeds.<br>Os genĂłtipos de <FONT FACE="Symbol">k</FONT>-caseĂ­na (<FONT FACE="Symbol">k</FONT>-CN), <FONT FACE="Symbol">b</FONT>-lactoglobulina (<FONT FACE="Symbol">b</FONT>-LG) e hormĂŽnio de crescimento foram determinados por reação em cadeia de polimerase (PCR) e digestĂŁo com enzima de restrição em sete raças de bovinos (Nelore, Gir, GuzerĂĄ, Caracu, Charolesa, Canchim and Santa Gertrudis). A <FONT FACE="Symbol">k</FONT>-caseĂ­na apresentou dois alelos e as freqĂŒĂȘncias mais elevadas para o alelo A foram observadas em Bos indicus (0,93, 0,92 e 0,91% para as raças Gir, GuzerĂĄ e Nelore, respectivamente). A <FONT FACE="Symbol">b</FONT>-lactoglobulina apresentou dois alelos em todas as raças estudadas, sendo a freqĂŒĂȘncia do alelo A mais elevada nas raças europĂ©ias. O loco de hormĂŽnio de crescimento apresentou dois alelos em Bos taurus e foi monomĂłrfico (alelo L) em todas as raças zebuĂ­nas. A maior freqĂŒĂȘncia para o alelo V foi observado na raça Charolesa. Os marcadores investigados revelaram alta similaridade entre as raças, com a formação de dois grupos principais: um composto de raças zebuĂ­nas e a raça Santa Gertrudis e outro composto das raças europĂ©ias e a raça Canchim

    Supplementary Material for: Occurrence and Origin of Supernumerary Chromosomes in Partamona (Hymenoptera: Apidae: Meliponini)

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    Samples from 861 colonies of 12 <i>Partamona</i> species from 125 Brazilian localities were analysed for a SCAR marker specific to the B chromosomes of <i>P. helleri</i>. We identified the SCAR marker in 6 of the 12 species analysed, including 2 <i>(P. gregaria</i> and <i>P. chapadicola)</i> from the pearsoni clade. This is the first report on the presence of this marker in <i>Partamona</i> species that are not included in the cupira clade, which indicates that the B chromosomes probably are more widespread in this genus than previously thought. The analysis revealed a high frequency of the SCAR marker in the samples of <i>P. helleri</i> (0.47), <i>P. cupira</i> (0.46), and <i>P. rustica</i> (0.29), and a low frequency in <i>P.</i> aff.<i>helleri</i> (0.06). The frequency of the marker in <i>P. helleri</i> was correlated with the latitude of the sampling locality, decreasing from north to south. Sequence data on the SCAR marker from 50 individuals of the 6 species in which the presence of this marker was shown revealed a new scenario for the origin of the B chromosomes in <i>Partamona</i>
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