Genetic mapping of Z chromosome and identification of W chromosome-specific markers in the silkworm, Bombyx mori

In the silkworm, Bombyx mori, the female is the heterogametic (ZW) sex and the male is homogametic (ZZ). The female heterogamety is a typical situation in the insect order Lepidoptera. Although the W chromosome in silkworm is strongly female determining, no W-linked gene for a morphological character has been found on it. The Z chromosome carries important traits of economic value as well as genes for various phenotypic traits, but only 2% of molecular information based on its relative size is known. Studies conducted so far indicate that the Z-linked genes are not dosage compensated. In the present study, we constructed a genetic map of randomly amplified polymorphic DNA fragments (RAPD), simple sequence repeats (SSR), and fluorescent intersimple sequence repeat PCR (FISSR) markers for the Z chromosome using a backcross mapping population. A total of 16 Z-linked markers were identified, characterized, and mapped using od, a recessive trait for translucent skin as an anchor marker yielding a total recombination map of 334.5 cM. The linkage distances obtained suggested that the markers were distributed throughout the Z chromosome. Four RAPD and four SSR markers that were linked to W chromosome were also identified. The proposed mapping approach should be useful to identify and map sex-linked traits in the silkworm. The economic and evolutionary significance of Z- and W-linked genes in silkworm, in particular, and lepidopterans, in general, is discussed.     

Organotin-induced hyperglycemia in the crab, Oziotelphusa senex senex Fabricius

Injection of three different organotin compounds such as tripalmitin, fentin and fenbutatin produced a significant increase in the hemolymph sugar level of intact crabs at Oziotelphusa senex senex apparently by stimulating release of the hyperglycemic hormone (HGH).     

Non-Invasive MRI and Spectroscopy of mdx Mice Reveal Temporal Changes in Dystrophic Muscle Imaging and in Energy Deficits

In Duchenne muscular dystrophy (DMD), a genetic disruption of dystrophin protein expression results in repeated muscle injury and chronic inflammation. Magnetic resonance imaging shows promise as a surrogate outcome measure in both DMD and rehabilitation medicine that is capable of predicting clinical benefit years in advance of functional outcome measures. The mdx mouse reproduces the dystrophin deficiency that causes DMD and is routinely used for preclinical drug testing. There is a need to develop sensitive, non-invasive outcome measures in the mdx model that can be readily translatable to human clinical trials. Here we report the use of magnetic resonance imaging and spectroscopy techniques for the non-invasive monitoring of muscle damage in mdx mice. Using these techniques, we studied dystrophic mdx muscle in mice from 6 to 12 weeks of age, examining both the peak disease phase and natural recovery phase of the mdx disease course. T2 and fat-suppressed imaging revealed significant levels of tissue with elevated signal intensity in mdx hindlimb muscles at all ages; spectroscopy revealed a significant deficiency of energy metabolites in 6-week-old mdx mice. As the mdx mice progressed from the peak disease stage to the recovery stage of disease, each of these phenotypes was either eliminated or reduced, and the cross-sectional area of the mdx muscle was significantly increased when compared to that of wild-type mice. Histology indicates that hyper-intense MRI foci correspond to areas of dystrophic lesions containing inflammation as well as regenerating, degenerating and hypertrophied myofibers. Statistical sample size calculations provide several robust measures with the ability to detect intervention effects using small numbers of animals. These data establish a framework for further imaging or preclinical studies, and they support the development of MRI as a sensitive, non-invasive outcome measure for muscular dystrophy.     

Effect of alkyl substitution on H-bond strength of substituted amide-alcohol complexes

The effect of alkyl substitution (CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, and t-C₄H₉) on the hydrogen bond strengths (H-bond) of substituted amide-alcohol complexes has been systematically explored. B3LYP/aug-cc-pVDZ method was applied to a total of 215 alkyl substituted amide-alcohol complexes to delineate the effect of substitution on the H-bond strength; formamide-water complex is taken as reference point. Complexes are classified into five types depending on the hydrogen donor, acceptor and the site of alkyl substitution (Type-IA, Type-IIA, Type-IB, Type-IIB and Type-III). The strength of H-bond was correlated with geometrical parameters such as proton-acceptor (H∙∙∙∙Y) distance, the length of proton donating bond (X–H). In all the complexes N–H and O–H stretching frequencies are red-shifted. The effect of alkyl substitution on N–H and O–H stretching frequencies were analyzed. Topological parameters like electron density at H∙∙∙∙Y and X–H bond critical points as derived from atom in molecules (AIM) theory was also evaluated. When C = O group is participating in H-bond, the strength of H-bond decreases with increasing size of alcohols except for methanol (Type-IA, Type-III and Type-IB complexes). But it increases with increasing size of alkyl groups on amide and decreases with bulky groups. In the case of N–H group as H-bond donor, the strength of H-bond increases with increasing size of alcohols (Type-IIA and Type-IIB complexes) whereas decreases with increasing size of alkyl groups on amide. Type-IA, IIA, IB and IIB complexes exhibit good correlations among IE, H-bond distance and electron density at bcp. In Type-III complexes, average H-bond distance and sum of electron densities shows better correlation with IEs than the corresponding individuals. The correlation of IE less with electron density at RCP compared to sum of electron densities.     

Laboratory evaluation of grain protectant efficacy of different foliar extracts against maize weevil – Sitophilus zeamais (Motschulsky)

The present study was aimed to evaluate six indigenous plant extracts for their ability to protect maize from infestation by maize weevil Sitophilus zeamais (M). The plant extracts were tested for its toxicity by fumigation and grain surface coating methods. Further, the effects of botanical treatments on F1 progeny, seed emergence and antifungal activities were studied. The results indicated that the extracts of Eicchornia crassipes controlled the test insect in grain surface coating method (100%, P = 0.05). Further, the same plant extract had significantly reduced the development of F1 progeny (97 ± 0.7%). In germination experiments, T + UEx samples showed normal seed germination of maize. However, in T + Ex samples, the seed germination depended on the grain protectant efficacy of the tested botanical extracts. Always higher percantage seed germination was recorded in those treatments where there was less infestation. Extracts of Carica papaya had significantly reduced the incidence of seed-borne fungus Aspergillus flavus (4 ± 2.4%) and did not affect the seed germination when compared to other treatments and untreated control.     

Population structure and genetic analysis of different utility types of mango (Mangifera indica L.) germplasm of Andhra Pradesh state of India using microsatellite markers

Genetic analysis of 90 mango genotypes including juicy, table, dual and pickle types from different parts of Andhra Pradesh of India was carried out employing 143 mango-specific microsatellite markers. Of the 143, 34 were new mango-specific microsatellite loci isolated in the course of the present investigation by constructing an (CA) _n and (TG) _n -enriched genomic library. Characterization of the 90 genotypes resulted in the detection of 301 alleles from 106 polymorphic loci with an average of 2.87 alleles per locus and polymorphism information content of 0.67. UPGMA cluster analysis grouped all the genotypes into two major groups with a genetic similarity range of 47–88 %. Grouping of the genotypes based on the utility type was observed only at sub-cluster level. Study of population structure by a model-based STRUCTURE analysis revealed the germplasm to exist in four gene pools. Overall F _st of 0.11 indicated genetic differentiation between the populations to be low. Analysis of molecular variance revealed that major proportion of the variation was within the individuals (62.25 %). The molecular marker-based study of genetic diversity suggests that the germplasm studied representing the kind of variability would be a valuable genetic resource for future breeding and association mapping in search for new and novel alleles.     

A Systematic Search Method for the Identification of Tightly Packed Transmembrane Parallel α-Helices

Abstract

Membrane proteins play a major role in number of biological processes such as signaling pathways. The determination of the three-dimensional structure of these proteins is increasingly important for our understanding of their structure-function relationships. Due to the difficulty in isolating membrane proteins for X-ray diffraction studies, computational techniques are being developed to generate the 3D structures of TM domains. Here, we present a systematic search method for the identification of energetically favorable and tightly packed transmembrane parallel α-helices. The first step in our systematic search method is the generation of 3D models for pairs of parallel helix bundles with all possible orientations followed by an energy-based filter to eliminate structures with severe non-bonded contacts. Then, a RMS-based filter was used to cluster these structures into families. Furthermore, these dimers were energy minimized using molecular mechanics force field. Finally, we identified the tightly packed parallel α-helices by using an interface surface area. To validate our search method, we compared our predicted GlycophorinA dimer structures with the reported NMR structures. With our search method, we are able to reproduce NMR structures of GPA with 0.9Å RMSD. In addition, by considering the reported mutational data on GxxxG motif interactions, twenty percent of our predicted dimers are within in the 2.0Å RMSD. The dimers obtained from our method were used to generate parallel trimeric and tetramer TM structures of GPA and found that the structure of GPA might exist only in a dimer form as reported earlier.     

DnaJs,the critical drivers of Hsp70s: genome-wide screening,characterization and expression of DnaJ family genes in Sorghum bicolor

Molecular Biology Reports - The DnaJ/Hsp40s, are important components in the chaperone machine, and play pivotal roles in plant growth, development and stress tolerance. Sorghum, the semi-arid...