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.     

Nitrification Inhibitors from the root tissues of Brachiaria humidicola, a tropical grass

Nitrification inhibitory activity was found in root tissue extracts of Brachiaria humidicola, a tropical pasture grass. Two active inhibitory compounds were isolated by activity-guided fractionation, using recombinant Nitrosomonas europaea containing luxAB genes derived from the bioluminescent marine gram-negative bacterium Vibrio harveyi. The compounds were identified as methyl-p-coumarate and methyl ferulate, respectively. Their nitrification inhibitory properties were confirmed in chemically synthesized preparations of each. The IC50 values of chemically synthesized preparations were 19.5 and 4.4 microM, respectively. The ethyl, propyl, and butyl esters of p-coumaric and ferulic acids inhibited nitrification, whereas the free acid forms did not show inhibitory activity.     

Molecular cloning and characterization of cDNA encoding CD11b of cattle

CD18, the common β subunit of β₂-integrins, associates with four distinct chains to give rise to four different β₂-integrins: CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1), CD11c/CD18 (CR4), and CD11d/CD18. Previously, we and others showed that CD18 of LFA-1 serves as a receptor for Mannheimia haemolytica leukotoxin (Lkt). Level of expression of Mac-1 is higher than that of LFA-1 and other β₂-integrins on polymorphonuclear leukocytes (PMNs), which constitute the leukocyte subset most susceptible to Lkt. Hence, it is likely that CD18 of Mac-1 also mediates Lkt-induced cytolysis. Co-expression of CD11b and CD18 of cattle on Lkt-resistant cells is necessary to irrefutably demonstrate the role of Mac-1 in Lkt-induced cytolysis. This approach is hindered by lack of availability of complete sequence of cattle CD11b. Therefore, in this study, we cloned and sequenced the full length cDNA encoding cattle CD11b. The 3459 bp cDNA of cattle CD11b encodes a polypeptide of 1152 amino acids. The deduced amino acid sequence of CD11b of cattle exhibits 75% identity to that of humans and chimpanzees, 74% identity to that of dogs, and 70% identity to that of mice and rats. Availability of cattle CD11b cDNA should facilitate the elucidation of Lkt-receptor interactions in cattle and other species.     

Emergence of antigenic variants with in serotype A foot and mouth disease virus in India and evaluation of a new vaccine candidate panel

Emergence of genetically and antigenically divergent lineages/genotypes and poor intergenotypic antigenic coverage is a major concern in serotype A foot-and-mouth-disease virus (FMDV) in India. In 2009, to cover antigenic diversity emerged in serotype A virus field isolates, IND40/2000 was selected as the new vaccine strain for incorporation in the trivalent FMD vaccine formulation used in India. Although current vaccine strain (IND40/2000) covers most isolates antigenically, a few VP3(59)-deletion group isolates showed low r-value in routine vaccine matching exercise. The VP3(59)-deletion group within genotype 18 emerged first in late part of 2002 and in 2007 causing outbreaks along with non-deletion isolates of the same genotype. In case of emergence or re-emergence of more antigenically divergent isolates in future, a need for a new vaccine candidate to cover maximum isolates of both deletion and non-deletion group may arise. Four alternate candidate vaccine strains (IND281/2003, IND195/2007, IND360/2007 and IND123/2008) were selected based on set criteria and antigenic relationships with field isolates sampled between 2002 and 2009 were analyzed using a micro-neutralization test. Phylogenetic analysis based on capsid region of serotype A isolates revealed existence of two broad distinct clusters (VP3(59)-deletion and non-deletion group) within genotype 18. The VP3(59)-deletion group has diversified genetically with time giving rise to three different sub-lineages (clade18a, 18b and 18c). The present study indicates that the virus candidates IND281/2003 (VP3(59)-deletion group) and IND195/2007 (non-deletion group) can be used as an adjunct or alternative strain to currently used vaccine strain IND40/2000 in case of emergence of more antigenically divergent isolates in future.     

Expression of iron regulatory proteins in full-term swine placenta

In swine, even though the pregnant sows were with iron abundance, the inborn iron reserve of piglets was compromised. This indicates the insufficiency of molecular machinery involved in local placental iron flux. Here, we investigated the expression of iron regulatory proteins like hepcidin and ferroportin and also their association with iron reserve, inflammation and oxidative stress in placenta of full-term pregnant sows (n = 6). Amplification and sequencing of placental DNA confirmed the presence of hepcidin (MN579557) and ferroportin (MN565887) sequences and their 100% identity with existing GenBank data. Real-time amplification of placental mRNA revealed significant higher expression of hepcidin (p < .05) than ferroportin. Western blot analysis of placental tissues revealed specific bands for both hepcidin (~8 kDa) and ferroportin (~62 kDa) molecules. Immunohistochemistry revealed the immunoreactivity for both proteins in the cytoplasm and membrane of trophoblastic cells of the placenta. Hepcidin and ferroportin expressions were positively associated with placental non-haem iron reserve (p < .0001; p = .033), lipid peroxidation (p = .0060; p < .0001) and reactive oxygen species level (p = .0092; p = .0292). Hepcidin expression was positively associated with interleukin – 6 (p = .0002) and interferon gamma (p < .0001) expressions but ferroportin expression was negatively associated with interleukin-6 (p = .0005), interleukin-1β (p = .0226) and interferon gamma (p = .0059) expressions. This indicates hepcidin and ferroportin may have a role in controlling the local placental iron flux by acting as a molecular bridge between iron trafficking and inflammation.     

Effect of Feronia limonia on mosquito larvae.

Bioassay guided fractionation of the acetone extract of Feronia limonia dried leaves afforded a potent mosquito larvicide, identified as n-hexadecanoic acid and found to be effective against fourth instar larvae of Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti, with LC50 of 129.24, 79.58 and 57.23 ppm, respectively.     

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.     

Crystal Structure of Tl2Ba2Ca2Cu3O10, a 125 K Superconductor

There is now a new series of high-temperature superconductors that may be represented as (A(III)O)(2)A(2)(II)Can-1CunO2+2n where A(III) is Bi or Tl, A(II) is Ba or Sr, and n is the number of Cu-O sheets stacked consecutively. There is a general trend toward higher transition temperatures as n increases. The highest n value for a bulk phase is three and is found when A(III) is Tl. This compound, Tl(2)Ba(2)Ca(2)Cu(3)O(10), has the highest transition temperature( approximately 125 K) of any presently known bulk superconductor. The structure of Tl(2)Ba(2)Ca(2)Cu(3)O(10) has been determined from single-crystal x-ray diffraction data and is tetragonal, with a = 3.85 A and c = 35.9 A. No superstructure is observed, and the material is essentially twin-free. Electron microscopy in the Tl/Ba/Ca/Cu/O system has revealed intergrowths where n = 5; such regions may well be responsible for the superconducting onset behavior observed in this system at about 140 K.     

Genetic studies in four interspecific hybrids of the genus oryza

The paper reports the results of genetic studies made in four interspecific hybrids of the genus Oryza, and the data are employed to discuss the inter-relationships between the different species. The characters of wild parents were found to be dominant in the F₁ hybrids.In O. sativa (variety Fukoku) × O. perennis subsp. balunga, the inheritance of the eight characters studied was found to be of the same nature as that of complementary, modifying, duplicating and polygenic types involving two or three genes. In O. perennis (Cuban type) × O. perennis subsp. balunga, the interesting feature was the occurrence of recessive characters (typical of cultivated rices) in the F₂ population, even though the two parents carried the dominant wild characters. This should be possible only by the operation of duplicate genes and such a mode of inheritance was observed for three characters. No definite Mendelian ratios could be got for the remaining five characters studied. The appearance of characters of cultivated rices has been suggested to point to the ability of O. perennis to give rise to O. sativa through natural crossing and selection. In O. glaberrima × O. perennis subsp. balunga, the ten characters studied segregated in monogenic or digenic fashion. When digenic, these characters exhibited complementary or inhibitory factor interactions. In O. glaberrima × O. breviligulata, the simple mode of inheritance in the F₂ generation has been suggested to indicate the close relationship of the two species.Some of the general features of the hybrids and segregating populations studied were the vigorous and fertile F₁s followed by the appearance of weak and unthrifty plants in the F₂ generation and the tendency for the parental characters to inherit together. The appearance of plants looking similar to O. sativa var. fatua in the F₂ populations of O. sativa × O. perennis, and of O. stapfii in the F₂s of O. glaberrima × O. perennis has been supposed to provide further evidence on the hybrid origin of these two forms.