Genetic Analysis of Izoenzymes Polymorphisms in Silkworm (Bombyx mori L.) Strains

Abstract

This work carried out to evaluates the polymorhism in the silkworm of different lineages using the isoenzymes electrophoresis to detect biochemical markers and to investigate the genetics of populations for those lineages. They were used as samples individual extracts of silk glands of second day old larvas of the fifth instar, originating from seven Japanese lineages and eight pure Chinese lineages maintained by the Cocamar-Cooperativa Agroindustrial de Maringá. The isozymes acid phosphatase (ACP), alkaline phosphatase (AKP) and carbonic anhydrase (CA) they were submitted to the electrophoresis in starch gels 14%. The esterases (EST) were analyzed in polyacrylamide gels to 10% and stained with α and β-naphtyl acetate. The total of 21 loci was detected, and 04 (19.05%) they are polymorphic, Est-11, Acp, Akp, Ca. The fixation index (F is ) for the analyzed isozymes it was 0.0751, indicating excess of homozygotes. The value of F st (0.6128) it shows that the lineages are well differentiated. The dendrogram obtained with the values of genetic distance didn't separate the Chinese and Japanese lineages analyzed totally. That preliminary evaluation of the lineages of B. mori shows that they present genetic material that it can be used in breeding programs that have the purpose of producing hybrid for silk production.Análise genética de polimorfismos bioquímicos em linhagens do bicho da seda (Bombyx mori L.) RESUMO. Este trabalho teve como objetivo avaliar o polimorfismo em lagartas do bicho-da-seda de diferentes linhagens utilizando a eletroforese de isoenzimas para detectar marcadores bioquímicos e investigar a genética de populações para essas linhagens. Foram utilizados como amostras extratos individuais de glândulas sericígenas de lagartas do segundo dia da quinta idade, de sete linhagens japonesas e oito linhagens chinesas puras mantidas pela Cocamar-Cooperativa Agroindustrial de Maringá. As isozimas fosfatase ácida (ACP), fosfatase alcalina (AKP) e anidrase carbônica (CA) foram avaliadas por meio de eletroforese em géis de amido de milho a 14%. As esterases (EST) foram analisadas por meio de eletroforese vertical em géis de poliacrilamida a 10% e coloração com α e β-naftil acetato. Foram observados 21 locos, dentre os quais quatro (19.05%) são polimórficos, Est-11, Acp, Akp, Ca. O índice de fixação (F is ) para as isozimas analisadas foi 0.0751, indicando excesso de homozigotos. O valor de F st (0.6128) permite sugerir que as linhagens estão bem diferenciadas. O dendograma obtido a partir dos valores de distância genética não separou totalmente as linhagens chinesas e japonesas analisadas. Essa avaliação preliminar das linhagens de B. mori mostra que elas apresentam material genético que pode ser utilizado em programas de cruzamentos que tenham a finalidade de produzir híbridos para produção de seda.Palavras-chave: bicho-da-seda, polimorfismos genéticos, isoenzimas.

Genetic Divergence, Implication of Diversity, and Conservation of Silkworm,Bombyx mori

“…The diversity study carried out in silkworm through protein profiles, enzymes, and isozymes are summarized in Table 2. Isozymes like esterase, acid phosphatase, alkaline phosphatase, amylase, phosphoglucomutase, aspartate aminotransferase, malate dehydrogenase, glucose 6 phosphate dehydrogenase, and carbonic anhydrase have been used by various authors to study diversity in silkworm genotypes [30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Among the different isoenzymes analyzed, esterase was most preferred because of its diverse substrate specificity and polymorphic expression followed by acid phosphatase [36,37,44].…”

“…18 [42] and 3 Nei (1978) and UPGMA Japanese and Chinese strains could not be totally separated by the isoenzyme system analysis. The results indicate that, in spite of the genetic distance and differentiation among the lineages, they cannot be separate just with the isozymes alleles.…”

“…Yoshitake et al [45] analyzed polymorphism pattern of esterase and acid phosphates in 300 strains of silkworm and concluded that distribution of acid phosphatase and esterase was similar in European and Japanese strains and there was resemblance between Chinese and European strains. A higher degree of interstrain variability was reported on the acid phosphatase [43,44] and esterase [36,37,41,42]. Acid phosphatase is also found to be a suitable marker for analyzing the inter-and intrastrain diversity and the strain International Journal of Biodiversity 5 differentiation [44].…”