Polyphasic phenotypic and genetic analysis reveals clonal nature of Xanthomonas axonopodis pv. punicae causing pomegranate bacterial blight

Yellow-pigmented bacteria isolated from blight-affected pomegranate leaves and fruit across seven Indian states in epidemics during the years 2008–2016 were characterized and identified using phenotypic and genotypic tools. All bacterial isolates shared phenotypic traits such as colony morphology, NaCl and pH sensitivity and fuscan production, and caused typical lesions on pomegranate plants upon artificial inoculation. Analysis of 16S ribosomal DNA and 16S–23S rDNA intergenic spacer sequences confirmed their identity as Xanthomonas axonopodis pv. punicae. The new isolates collected after 2000 were compared with an old isolate from the 1950s using polyphasic taxonomic approaches including multilocus sequence analysis (MLSA). Nucleotide polymorphism in 24 isolates for nine genomic loci (dnaK, fyuA, gyrB (Young), gyrB (Almeida), rpoD, fusA, gapA, gltA and lepA) showed minor variations in loci fyuA and gyrB. Isolates were grouped into four nearly identical sequence types, ST1, ST2, ST3 and ST4, based on their allelic profiles, ST3 being widespread in Indian states. Molecular phylogenetic analysis of concatenated 5690 bp with other Xanthomonas pathovars revealed its close genetic similarity with the X. citri group. The blight outbreak in diverse geographical locations is attributed to a re-emerged clonal population of X. axonopodis pv. punicae on a genetically homogenous pomegranate cultivar. The latently infected vegetative planting material of elite pomegranate cultivars contributed to the dissemination of the bacterial inoculum. This study highlights and forewarns of the role played by the clonally propagated elite pomegranate cultivars in disseminating and sustaining clonal populations of this bacterial plant pathogen in many Indian states.     

Efficacy of two organotin compounds and neem extract against the sorghum shoot fly

The antifeedants triphenyltin acetate and hydroxide and neem seed kernel extracts in two concentrations each, were evaluated as control measures against the sorghum shoot fly,Atherigonu varia soccata Rond. in comparison with the insecticides presently used for this purpose. The antifeedants appeared to be partially effective and were less active than the insecticides.     

Application of silver nanoparticles to industrial sewing threads: Effects on physico-functional properties & seam efficiency

In this study, the role and impact of silver nanoparticles on industrial sewing threads have been investigated. Study of nanocoating on industrial sewing threads may be useful especially in the areas where skin comes in contact with the garments where anti-bacterial properties may be very useful. Silver particles are considered to have excellent anti bacterial properties. To understand the impact on sewability, investigation was focused to changes at the structural level, changes in physical and surface properties, tensile properties and anti-microbial properties of the nanotreated sewing threads. The structure and morphology of the silver nanoparticles on the sewing threads was observed by scanning electron microscopy (SEM) and quantitatively confirmed by fourier transform infrared spectroscopy (FT-IR). A number of experimental methods and mathematical formulae were used to test individual threads. Custom designed fixtures were used for the study. All the results have been statistically analyzed and found to be significant. The effect of silver nanoparticles on physical properties, functional properties and seam efficiency was illustrated. The difference of the impact of silver nanoparticles on cotton and polyester sewing threads has been compared. It was found that silver nanotreatment leads to a significant reduction of tensile strength. The warp-way seam strength increased where as weft-way seam strength decreased due to damage of yarn. Deformation properties of the threads are not influenced significantly by nanotreatment. The nanotreatment of threads improves its frictional properties significantly. The threads also acquire effective anti-microbial properties with silver nanotreatment. Study of the impact of nanotreatment on the properties of cotton and polyester samples showed a bigger impact on cotton samples than polyester samples. The effect was durable even after several laundering treatments.     

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.     

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.     

Incidence and avoidance of zona fracture in cryopreserved bovine ova and embryos

Ova (n=62), which were collected from slaughterhouse bovine ovaries, and embryos (n=26), which were non-surgically recovered from 11 superovulated crossbred donor cows, were frozen. The frozen ova and embryos were then thawed using two conventional thawing protocols, i.e. at 37 degrees C for 30 seconds in a water bath and at 25 degrees C for 2 minutes in air. Some 64.5% of the ova and 53.8% of the embryos thawed in the water bath and 16.1% of the ova and 7.7% of the embryos thawed in ambient air exhibited fractured zonae pellucidae. The slow thawing protocol had a lower incidence of zona damage in cryopreserved oval and embryos than the fast thawing protocol. A low pregnancy rate (12.5%) was recorded for embryos transferred with zona fracture while embryos transferred with intact zonae had a rate of 35.3%) indicating that embryos with zona damage are less viable.     

Viral interference with MHC class I antigen presentation pathway: the battle continues

CD8+ cytotoxic T lymphocytes (CTLs) play a critical role in the defense against viral infections. In general, CD8+ CTLs recognize antigenic peptides in the context of the major histocompatibility complex (MHC) class I molecule. The MHC class I molecules are expressed on almost all the nucleated cells in the body. The trimolecular complex consisting of the class I heavy chain, beta2-microglobulin and the peptide are generated by the MHC class I antigen presentation pathway. This pathway is designed to sample the intracellular milieu and present the information to the CTLs trafficking the area. This rigorous sampling of intracellular environment enables the CTLs to quickly identify and eliminate the cells that synthesize non-self proteins as a result of a viral infection. Many viruses, including several viruses of veterinary importance, have evolved astounding strategies to interfere with the MHC class I antigen presentation pathway, as a means of evading the CTL response of the host. This review focuses on the diverse mechanisms of viral evasion of the MHC class I antigen presentation pathway with particular emphasis on viruses of veterinary importance.