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Biochemical Genetics (v.39, #9-10)

Differential Esterase Expression in Leaves of Manihot esculenta Crantz Infected with Xanthomonas axonopodis pv. manihotis by Álvaro Júlio Pereira; Ana Sílvia Lapenta; Pedro Soares Vidigal-Filho; Maria de Fátima P. S. Machado (pp. 289-296).

The polyacrylamide gel electrophoresis system (PAGE) and inhibition tests for biochemical characterization of α- and β-esterases were used to obtain a functional classification of esterases in plants and to show a differential expression of esterases as markers of pathogenesis in cassava plants (Manihot esculenta Crantz). The characterization of α- and β-esterases from leaves of M. esculenta by the PAGE system was possible using an extraction solution containing two phenol-complexing agents (PVP-40 and sodium metabisulfite), three antioxidant agents (EDTA, β-mercaptoethanol, and DTT), and one quinone reducer (ascorbic acid). Fourteen esterase isozymes were detected in young unexpanded leaves of M. esculenta cultivars. The inhibition pattern of α- and β-esterases of M. esculenta showed that Est-9 is an arylesterase, and in the unexpanded leaves of the M. esculenta plants infected with Xanthomonas axonopodis pv. manihotis, the Est-7 β-esterase showed the characteristic staining of an α/β-esterase. This differential expression of Est-7 isozyme in young unexpanded leaves of cassava plants can be used as a marker of pathogenesis after infection with X. axonopodis pv. manihotis.

Keywords: esterase; cassava blight; bacteriosis; phytophatogenic xanthomonads

Comparative Analysis of Genetic Diversity Among Indian Populations of Scirpophaga incertulas by ISSR-PCR and RAPD-PCR by Lalitha Sunil Kumar; Arun S. Sawant; Vidya S. Gupta; Prabhakar K. Ranjekar (pp. 297-309).

Genetic variation between 28 Indian populations of the rice pest, Scirpophaga incertulas was evaluated using inter-simple sequence repeats (ISSR)-PCR assay. Nine SSR primers gave rise to 79 amplification products of which 67 were polymorphic. A dendrogram constructed from this data indicates that there is no geographical bias to the clustering and that gene flow between populations appears to be relatively unrestricted, substantiating our earlier conclusion based on the RAPD (random amplified polymorphic DNA) data. The dendrograms obtained using each of these marker systems were poorly correlated with each other as determined by Mantel's test for matrix correlation. Estimates of expected heterozygosity and marker index for each of these marker systems suggests that both these marker systems are equally efficient in determining polymorphisms. Matrix correlation analyses suggest that reliable estimates of genetic variation among the S. incertulas pest populations can be obtained by using RAPDs alone or in combination with ISSRs, but ISSRs alone cannot be used for this purpose.

Keywords: Scirpophaga incertulas ; inter-simple sequence repeat polymorphism; genetic diversity; average heterozygosity; marker index

Restriction Fragment Length Polymorphism (RFLP) in Exon 2 of the BoLA-DRB3 Gene in South American Cattle by M. M. Miretti; J. A. Ferro; M. A. Lara; E. P. B. Contel (pp. 311-324).

The Bola-DRB3 gene participates in the development of the immune response and is highly polymorphic. For these reasons, it has been a candidate gene in studies of the genetic basis of disease resistance and in population genetic analysis. South American native cattle breeds have been widely replaced by improved exotic breeds leading to a loss of genetic resources. In particular, South American native breeds have high levels of fertility and disease resistance. This work describes genetic variability in the BoLA-DRB3 gene in native (Caracu, Pantaneiro, Argentinean Creole) and exotic (Holstein, Jersey, Nelore, Gir) cattle breeds in Brazil and Argentina. PCR-RFLP alleles were identified by combining the restriction patterns for the BoLA-DRB3.2 locus obtained with RsaI, BstY, and HaeIII restriction enzymes. Allelic frequencies and deviations from the Hardy–Weinberg equilibrium were also calculated. Analysis of the 24 BoLA-DRB3 PCR-RFLP alleles identified showed differences in the allele distributions among breeds.

Keywords: MHC; DRB3; bovine; genetic variability

Molecular Marker Analysis of Protein Content Using PCR-Based Markers in Wheat by B. B. Dholakia; J. S. S. Ammiraju; D. K. Santra; H. Singh; M. V. Katti; M. D. Lagu; S. A. Tamhankar; V. S. Rao; V. S. Gupta; H. S. Dhaliwal; P. K. Ranjekar (pp. 325-338).

Grain protein concentration (GPC) of hexaploid wheat is one of the important factors that determines the end-product quality, as well as playing a pivotal role in human nutrition. In an attempt to identify PCR-based DNA markers linked to GPC, 106 recombinant inbred lines (RILs) were developed from a cross between two wheat cultivars PH132 and WL711, which differ significantly in GPC, by the single seed descent method. The RILs were phenotyped for GPC at two diverse agroclimatic locations, namely Pune and Ludhiana, to study the influence of genotype and environment interactions on this trait. The parents were screened with 85 inter simple sequence repeat (ISSR) primers and 350 random primers. The selective genotyping and whole population analysis revealed nine DNA markers associated with the trait. Three markers (UBC844₁₁₀₀, UBC880₁₁₀₀, and OPA4₈₀₀) were observed to be associated with the trait in both locations, whereas two markers (OPH4₁₄₀₀ and UBC873₇₅₀) were found to be specific to Pune, and four markers (OPM5₈₇₀, OPO10₈₇₀, OPV14₁₂₀₀, and UBC825₁₀₀₀) were specific to Ludhiana. Together five markers at the Pune location representing five QTLs and seven markers at Ludhiana representing four QTLs accounted for 13.4 and 13.5% of total phenotypic variation, respectively. This study clearly demonstrates that GPC is highly influenced by the environment, and the applicability of ISSR and RAPD markers in finding regions on chromosomes associated with quantitative characters in wheat such as GPC.

Keywords: wheat; grain protein concentration; molecular markers

Tissue-Specific and Developmental Effects of the Easily Shocked Mutation on Ethanolamine Kinase Activity and Phospholipid Composition in Drosophila melanogaster by Marian Nyako; Camille Marks; Joseph Sherma; Elaine R. Reynolds (pp. 339-349).

The easily shocked (eas) gene of Drosophila melanogaster encodes ethanolamine kinase (EK), the first step in phosphatidylethanolamine (PE) synthesis via the CDP-ethanolamine pathway. Flies mutant for eas display a complex neurological phenotype. In this paper, we look at the contribution of EK to lipid metabolism during Drosophila development with the goal of linking the eas biochemical defect with the organismal phenotype. Using a chromatography-based assay, EK activity was detected in wild-type flies throughout development. Most of the activity in the adult was present in heads, which is primarily tissue of neural origin. Flies mutant for eas showed severely reduced levels of activity at each stage assayed. Using standard extraction methods and thin layer chromatography, phospholipid composition was assayed in whole flies and in heads. While PE levels were decreased significantly in both tissues, heads also had significantly less phosphatidylserine (PS). Therefore, decreases in both phospholipids may play a role in producing the aberrant phenotype in eas flies.

Keywords: ethanolamine kinase; Drosophila ; bang-sensitive; phosphatidylethanolamine

Note: A MnlI Restriction Site Polymorphism in the Interleukin-10 Gene Promoter by Fang Zheng; Curtis Gabriel; Ashita Batavia; Xin Zhou; Shui Q. Ye (pp. 351-356).

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Biochemical Genetics (v.39, #9-10)