Superconducting and Magnetic Behavior in La2-xNaxCuO4

New phases of the type La2-xAx(l+)CUO4-y have been prepared where A(l+) is sodium or potassium. The sodium phases are superconducting for x values from 0.2 to 0.5 at temperatures up to about 40 K. In addition, there are unusual magnetic properties below about 10 K that may be indicative of spin glass behavior. Phases of the type La2-xKxCuO4-y could only be prepared with x values up to about 0.1, and these phases are not superconducting above 4.2 K.     

Insect antifeedant activity of tetranortriterpenoids from the Rutales. A perusal of structural relations

Structure-related insect antifeedant relationship of 56 limonoids (both natural and modified) from the plants belonging to the order Rutales was attempted considering substitution patterns, oxidation states, and hydrophobicity, as well as distant geometry derived through conformational analysis on molecular modeling. Orientation of the furan and hydroxylation at specific carbon sites have been shown to influence the antifeedancy against the fall armyworm, Spodoptera litura.     

Biological nitrification inhibition by Brachiaria humidicola roots varies with soil type and inhibits nitrifying bacteria, but not other major soil microorganisms

The tropical pasture grass Brachiaria humidiola (Rendle) Schweick releases nitrification inhibitory compounds from its roots, a phenomenon termed 'biological nitrification inhibition' (BNI). We investigated the influence of root exudates of B. humidicola on nitrification, major soil microorganisms and plant growth promoting microorganisms using two contrasting soil types, Andosol and Cambisol. The addition of root exudates (containing BNI activity that is expressed in Allylthiourea unit (ATU) was standardized in a bioassay against a synthetic inhibitor of nitrification, allylthiourea, and their function in soil was compared to inhibition caused by the synthetic nitrification inhibitor dicyandiamide. At 30 and 40 ATU g⁻¹soil, root exudates inhibited nitrification by 95% in fresh Cambisol after 60 days. Nitrification was also similarly inhibited in rhizosphere soils of Cambisol where B. humidicola was grown for 6 months. Root exudates did not inhibit other soil microorganisms, including gram-negative bacteria, total cultivable bacteria and fluorescent pseudomonads. Root exudates, when added to pure cultures of Nitrosomonas europaea , inhibited their growth, but did not inhibit the growth of several plant growth promoting microorganisms, Azospirillum lipoferum , Rhizobium leguminosarum and Azotobacter chroococcum. Our results indicate that the nitrification inhibitors released by B. humidicola roots inhibited nitrifying bacteria, but did not negatively affect other major soil microorganisms and the effectiveness of the inhibitory effect varied with soil type.     

Green fluorescent protein visualization of Vibrio parahaemolyticus infections in Indian white shrimp Fenneropenaeus indicus (H Milne Edwards)

The pathways by which pathogens invade Fenneropenaeus indicus, the potential colonization in various tissues and the disease transmission mechanisms are unclear. The aims of the present study were to visualize the colonization and pathogenesis of GFP‐tagged Vibrio parahaemolyticus, in various tissues of F. indicus to evaluate the pathogen interaction. Among the three strains isolated, a virulent strain VpDAHV2 was tagged with green fluorescent protein (GFP‐VpDAHV2) and validated for both its growth characteristics and its virulence as a genuine model for F. indicus infection. VpDAHV2 was positive for toxR and tlh genes and negative for tdh genes. CLSM images revealed that maximum colonization was observed in the haemolymph of the F. indicus challenged with GFP‐VpDAHV2. The haemolymph was the primary site for the colonization of GFP‐VpDAHV2 in F. indicus. The enteric localization occurred independently of the flagellum or motility of GFP‐VpDAHV2 through the intestinal route. The F. indicus infection model suggests that the haemolymph and the intestine represent the sites of infection by GFP‐VpDAHV2, and hence are the active sites of pathogen interactions. GFP tagging of V. parahaemolyticus is a new and systemic approach to determine the presence of bacteria in vivo for the confirmation of host pathogen interactions in aquaculture studies.     

Integrating marker assisted background analysis with foreground selection for identification of superior bacterial blight resistant recombinants in Basmati rice

Basmati rice is highly susceptible to bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae. Transfer of BB resistance genes from non‐Basmati sources to Basmati through cross‐hybridization requires strict monitoring for recovery of the desirable Basmati quality traits in the recombinants, which show complex inheritance pattern. We integrated background analysis using mapped microsatellite markers with foreground selection to identify superior lines that combine useful genes from a non‐Basmati BB resistance donor line IRBB55 with grain and cooking quality characteristics of the popular Basmati rice variety ‘Pusa Basmati 1’ (PB 1) employing backcross pedigree strategy. Foreground selection using linked markers ensured presence of two genes, xa13 and Xa21 for BB resistance from IRBB55, and the recurrent parent PB 1 allele for the waxy locus giving intermediate amylose content and maintainer allele at fertility restorer locus in the BC₁F₅ recombinants. Background analysis enabled selection of recombinants with recurrent parent genome to the extent of 86.3% along with the quality traits. The extent of introgression of non‐Basmati donor chromosome segments in the superior selections was estimated to be < 7.8 Mb and < 6.7 Mb in the xa13 and Xa21 linked genomic regions, respectively. Association mapping identified three quantitative trait loci, one each for 1000‐grain weight, fertile grains/panicle and cooked kernel length. The backcross‐pedigree breeding strategy facilitated recovery of additional desirable characteristics from the donor in some of the selections. The elite selection Pusa 1460‐01‐32‐6‐7‐67 with maximum genomic background and quality characteristics of the recurrent Basmati parent gave resistance reaction against BB, similar to that of the non‐Basmati resistant check variety and recorded an yield advantage of 11.9% over the best check in the multiplication agronomic trial in the Basmati growing region of India. This line, which has been released as a new variety in the name of ‘Improved Pusa Basmati 1’ for commercial cultivation in India, is an example of successful application of marker assisted selection to variety development.     

The biochemical correlation between the epicuticular wax of upland cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) and the wax of different mealybug species

The study aimed to find the possible differences, existing between the cuticular waxes of cotton and mealybug insects, using advanced analytical studies. The biochemical composition of the leaf wax of upland cotton (Gossypium hirsutum L.) and the cuticular wax of the different mealybug species, including Phenacoccus solenopsis Tinsley, Ferrisia virgata Cockerell, Paracoccus marginatus Williams and Granara de Willink, and Drosicha mangiferae Green were analyzed in detail by Gas Chromatography-Mass Spectrometry (GC-MS). The results clearly confirmed that the cotton wax is dominated by the six-carbon alkanes, while the mealybug wax is a mixture of both the five-carbon alkanes and the six-carbon alkanes. Apart from these differences, the common hydrocarbons such as hexadecane, icosane, and heneicosane, the uncommon hydrocarbons such as ethane, cyclobutanone, decane, and cyclododecane, the species-specific compounds of mealybugs such as myristyl alcohol, quinoline, hexacosane, and pentacosane were also identified and their retention times (RT) were listed out in detail. The outcome of this study will be useful to develop pest management techniques targeting the waxy cuticle of mealybugs without obstructing the normal physiology and growth of the cotton crop.     

Diversity of the cultivable gut bacterial communities associated with the fruit flies <Emphasis Type="Italic">Bactrocera dorsalis</Emphasis> and <Emphasis Type="Italic">Bactrocera cucurbitae</Emphasis> (Diptera: Tephritidae)

Gut microbes play an important role in insect morphogenesis, nutrition, development of resistance against parasitoids and detoxification of toxic compounds. A culture-based approach is therefore an useful tool for the characterization of cultivable microbial communities associated with the insect gut. In the present study an attempt was made to decipher the gender specificity of gut bacterial communities of two major fruit fly species of India viz., Bactrocera dorsalis (Hendel) and Bactrocera cucurbitae (Conquillett) (Diptera: Tephritidae). Based on molecular identification, B. dorsalis females were found to predominantly harbor the bacterial species Enterobacter cloacae, Enterobacter asburiae and Citrobacter freundii, while B. dorsalis males were found to harbor Providencia rettgerii, Klebsiella oxytoca, Enterococcus faecalis and Pseudomonas aeruginosa The cultivable diversity from females of B. cucurbitae comprised mainly of Morganella morganii and Bacillus pumilis while B.cucurbitae males were predominantly colonized by aerobic endospore formers viz., Bacillus cereus, B. licheniformis and B. subtilis. The above findings have thrown light on a distinct pattern of gender specific gut bacterial colonization in fruit flies, which have to be factored in for the formulation of fruit fly management strategies.     

Bighorn sheep fetal lung cell line for detection of respiratory viruses

Pneumonia is an important disease of bighorn sheep (BHS) that is primarily responsible for the drastic decline in numbers of these animals in North America. Members of the genus Mannheimia and Pasteurella have frequently been isolated from the pneumonic lungs of BHS. Antibodies to several respiratory viruses, including bovine parainfluenza virus 3 (BPIV-3), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), and bovine herpesvirus 1 (BoHV-1), have been detected in herds of BHS. The availability of BHS fetal lung cell lines is likely to enhance the chances of isolation of these viruses. Here we report the development of such a cell line. This line is permissive for BPIV-3, BRSV, BVDV, and BoHV-1 infection, as revealed by an enzyme immunoassay of virus-infected cells with antibodies specific for each of these viruses. This cell line should be valuable for detecting these 4, and possibly other, respiratory viruses in BHS.     

Development and characterization of tomato SSR markers from genomic sequences of anchored BAC clones on chromosome 6

Simple sequence repeat motifs are abundant in plant genomes and are commonly used molecular markers in plant breeding. In tomato, currently available genetic maps possess a limited number of simple sequence repeat (SSR) markers that are not evenly distributed in the genome. This situation warrants the need for more SSRs in genomic regions lacking adequate markers. The objective of the study was to develop SSR markers pertaining to chromosome 6 from bacterial artificial chromosome (BAC) sequences available at Solanaceae Genomics Network. A total of 54 SSR primer pairs from 17 BAC clones on chromosome 6 were designed and validated. Polymorphism of these loci was evaluated in a panel of 16 genotypes comprising of Solanum lycopersicum and its wild relatives. Genetic diversity analysis based on these markers could distinguish genotypes at species level. Twenty-one SSR markers derived from 13 BAC clones were polymorphic between two closely related tomato accessions, West Virginia 700 and Hawaii 7996 and were mapped using a recombinant inbred line population derived from a cross between these two accessions. The markers were distributed throughout the chromosome spanning a total length of 117.6 cM following the order of the original BAC clones. A major QTL associated with resistance to bacterial wilt was mapped on chromosome 6 at similar location of the reported Bwr-6 locus. These chromosome 6-specific SSR markers developed in this study are useful tools for cultivar identification, genetic diversity analysis and genetic mapping in tomato.     

Evaluation of actinomycete isolates obtained from herbal vermicompost for the biological control of Fusarium wilt of chickpea

A total of 137 actinomycetes cultures, isolated from 25 different herbal vermicomposts, were characterized for their antagonistic potential against Fusarium oxysporum f. sp. ciceri (FOC) by dual-culture assay. Of the isolates, five most promising FOC antagonistic isolates (CAI-24, CAI-121, CAI-127, KAI-32 and KAI-90) were characterized for the production of siderophore, cellulase, protease, hydrocyanic acid (HCN), indole acetic acid (IAA) and antagonistic potential against Rhizoctonia bataticola, which causes dry root rot in chickpea (three strains viz. RB-6, RB-24 and RB-115) and sorghum (one strain). All of the five FOC antagonistic isolates produced siderophore and HCN, four of them (except KAI-90) produced IAA, KAI-32 and KAI-90 produced cellulase and CAI-24 and CAI-127 produced protease. In the dual-culture assay, three of the isolates, CAI-24, KAI-32 and KAI-90, also inhibited all three strains of R. bataticola in chickpea, while two of them (KAI-32 and KAI-90) inhibited the tested strain in sorghum. When the FOC antagonistic isolates were evaluated further for their antagonistic potential in the greenhouse and wilt-sick field conditions on chickpea, 45-76% and 4-19% reduction of disease incidence were observed, respectively compared to the control. The sequences of 16S rDNA gene of the isolates CAI-24, CAI-121, CAI-127, KAI-32 and KAI-90 were matched with Streptomyces tsusimaensis, Streptomyces caviscabies, Streptomyces setonii, Streptomyces africanus and an identified species of Streptomyces, respectively using the BLAST searching. This study indicated that the selected actinomycete isolates have the potential for biological control of Fusarium wilt disease in chickpea.