Effect of the wingless (wg1) mutation on wing and haltere development in Drosophila melanogaster

Genetic and developmental studies of wingless (wg¹), a new second chromosome recessive mutation in Drosophila melanogaster, have shown that it affects not only wing and haltere development (giving rise to wingless and/or halterless flies), but also results in various abnormalities of the mesothorax. The larvae destined to develop into wingless and/or halterless flies possessed underdeveloped mesothoracic and/or metathoracic imaginal discs.     

Induction of term labor with intravenous prostaglandin F2α (a comparison of two dosage schedules)

The efficacy of intravenous Prostaglandin F_2α (PGF_2α) infusion for induction of labor in two different dosage schedules was studied in 90 women between 36 and 43 weeks of gestation. The rate of PGF_2α infusion was increased at four-hour intervals in 36 women in the low dosage group and every hour in 54 women in the high dosage group, never exceeding an infusion rate of 20 μg/min. in either group. Labor was successfully induced in approximately 90% of the patients in each group. There was no statistically significant difference in the mean induction-delivery interval between the two groups at the 5 percent level. Intravenous PGF_2α was found to be effective and safe for both mother and infant in the dosage schedules used in this study for induction of labor.     

Brain biogenic amines: depletion by chronic dieldrin exposure

Chronic dietary exposure to dieldrin in mallard ducks caused an appreciable depletion of brain serotonin, norepinephrine and dopamine, but not of gamma-aminobutyrate. Such alterations may account for the toxic effects in animals following chronic pesticide exposure. Changes in brain biogenic amines may possibly be related to behavioral disorders following exposure to such environmental contaminants.     

The Residue Threonine 82 of DevR (DosR) Is Essential for DevR Activation and Function in Mycobacterium tuberculosis Despite Its Atypical Location

The DevR (DosR) response regulator initiates the bacterial adaptive response to a variety of signals, including hypoxia in in vitro models of dormancy. Its receiver domain works as a phosphorylation-mediated switch to activate the DNA binding property of its output domain. Receiver domains are characterized by the presence of several highly conserved residues, and these sequence features correlate with structure and hence function. In response regulators, interaction of phosphorylated aspartic acid at the active site with the conserved threonine is believed to be crucial for phosphorylation-mediated conformational change. DevR contains all the conserved residues, but the structure of its receiver domain in the unphosphorylated protein is strikingly different, and key threonine (T82), tyrosine (Y101), and lysine (K104) residues are placed uncharacteristically far from the D54 phosphorylation site. In view of the atypical location of T82 in DevR, the present study aimed to examine the importance of this residue in the activation mechanism. Mycobacterium tuberculosis expressing a DevR T82A mutant protein is defective in autoregulation and supports hypoxic induction of the DevR regulon only very weakly. These defects are ascribed to slow and partial phosphorylation and the failure of T82A mutant protein to bind cooperatively with DNA. Our results indicate that the T82 residue is crucial in implementing conformational changes in DevR that are essential for cooperative binding and for subsequent gene activation. We propose that the function of the T82 residue in the activation mechanism of DevR is conserved in spite of the unusual architecture of its receiver domain.     

Genetic Improvement and Crop Management Strategies to Minimize Yield Losses in Warm Non-traditional Wheat Growing Areas due to Spot Blotch Pathogen Cochliobolus sativus

Spot blotch caused by Cochliobolus sativus emerged as a major threat to wheat production in the warmer non-traditional wheat growing areas in the late 1980s. This foliar disease causes significant yield losses annually (15–20% on average in South Asia) endangering the livelihoods of millions of small farmers. Effective measures in the field are needed to mitigate the impact of spot blotch on food security in affected areas. This review summarizes the global knowledge on genetic improvement and crop management strategies to minimize yield losses based on latest field research. Recent studies have shown that spot blotch severity is highly influenced by stress factors affecting crop physiology which in turn affects host tolerance and resistance to the pathogen. Soil nutrient and water stress aggravate spot blotch-induced grain yield losses. Heat stress which is gradually increasing in Asia causes higher levels of disease damage. Genetic improvement is the cornerstone of a sustainable control of spot blotch in all affected regions. Resistance is essentially based on Chinese and South American sources and inter-specific crosses with broadly adapted semi-dwarf germplasm. A list of genotypes consistently reported in the last 10 years to harbor at least partial resistance to spot blotch, along with their inheritance of resistance, has been compiled to help breeding programmes. As the fungus is aggressive under conditions of high relative humidity and heat which in turn influences plant susceptibility, a synthesis of the different tools for scoring disease severity is given. Because resistance is incomplete, the ultimate goal is the accumulation of minor genes of resistance in adapted high yielding genotypes. This paper shows how the use of resistant varieties, timely seeding, adequate fertilization, crop rotation, and the judicious use of fungicides can be part of an integrated management strategy for controlling yield losses due to spot blotch.     

Construction of a Genetic Linkage Map and Identification of QTLs for Seed Weight and Seed Size Traits in Lentil (Lens culinaris Medik.)

Seed weight and seed size both are quantitative traits and have been considered as important components of grain yield, thus identification of quantitative trait loci (QTL) for seed traits in lentil (Lens culinaris) would be beneficial for the improvement of grain yield. Hence the main objective of this study was to identify QTLs for seed traits using an intraspecific mapping population derived from a cross between L. culinaris cv. Precoz (seed weight-5.1g, seed size-5.7mm) and L. culinaris cv. L830 (seed weight-2.2g, seed size-4mm) comprising 126 F₈-RILs. For this, two microsatellite genomic libraries enriched for (GA/CT) and (GAA/CTT) motif were constructed which resulted in the development of 501 new genomic SSR markers. Six hundred forty seven SSR markers (including 146 previously published) were screened for parental polymorphism and 219 (33.8%) were found to be polymorphic among the parents. Of these 216 were mapped on seven linkage groups at LOD4.0 spanning 1183.7cM with an average marker density of 5.48cM. Phenotypic data from the RILs was used to identify QTLs for the seed weight and seed size traits by single marker analysis (SMA) followed by composite interval mapping (CIM) which resulted in one QTL each for the 2 traits (qSW and qSS) that were co-localized on LG4 and explained 48.4% and 27.5% of phenotypic variance respectively. The current study would serve as a strong foundation for further validation and fine mapping for utilization in lentil breeding programs.     

Purification and Characterization of Recombinant Polymeric Hemoglobin P1 of Glycera dibranchiata

The apoprotein of component P1 of the polymeric fraction of the intracellular hemoglobin of the marine polychaete Glycera dibranchiata has been expressed at a high level in Escherichia coli. The expressed globin was reconstituted with heme and purified. The N-terminal sequence of the recombinant P1 is identical to the cDNA-derived sequence of cloned P1 (Zafar et al., Biochem. Biophys. Acta, 1041, 117-123, 1990). Gel filtration, SDS-PAGE, optical spectra over the range 200-650 nm, and circular dichroism over the range 200-250 nm of the purified recombinant P1 were very similar to the polymeric fraction of native Glycera hemoglobin. The molar ellipticity at 222 nm provided an estimate of 77% for the α-helical content of the recombinant P1, in excellent agreement with that calculated from the crystal structure of Glycera monomeric component M-II. Although the oxygen binding affinity of the recombinant P1 is higher than that of the polymeric fraction of Glycera hemoglobin (3-4 torr vs 7-13 torr), which consists of at least six different single-chain hemoglobins, the Hill coefficient is lower (1.0-1.2 vs 1.2-1.4).     

Glutathione S-transferase-catalyzed conjugation of 9,10-epoxystearic acid with glutathione

The possible role of glutathione S-transferases (GST) in detoxification of fatty acid epoxides generated during lipid peroxidation has been evaluated. Present studies showed that cytosolic human glutathione S-transferases belonging to alpha, mu, and pi classes isolated from human liver and lung catalyzed the conjugation of glutathione and 9,10-epoxystearic acid. The product of enzymatic reaction, i.e., conjugate of GSH and epoxystearic acid, was isolated and characterized. The Michaelis constant (Km) values of the alpha, mu, and pi classes of GSTs for 9,10-epoxystearic acid were found to be 0.47, 0.32 and 0.80 mM, respectively, whereas the maximal velocity (V max) values for the alpha, mu, and pi classes of GSTs were found to be 142, 256, and 52 mol/min/mol, respectively. These results indicate that even though 9,10-epoxystearic acid is a substrate for all the three classes of GSTs, the mu class isozymes have maximum activity toward this substrate and may preferentially metabolize fatty acid epoxides more effectively as compared to the other classes of GSTs.