Optimizing purebred selection for crossbred performance using QTL with different degrees of dominance

A method was developed to optimize simultaneous selection for a quantitative trait with a known QTL within a male and a female line to maximize crossbred performance from a two-way cross. Strategies to maximize cumulative discounted response in crossbred performance over ten generations were derived by optimizing weights in an index of a QTL and phenotype. Strategies were compared to selection on purebred phenotype. Extra responses were limited for QTL with additive and partial dominance effects, but substantial for QTL with over-dominance, for which optimal QTL selection resulted in differential selection in male and female lines to increase the frequency of heterozygotes and polygenic responses. For over-dominant QTL, maximization of crossbred performance one generation at a time resulted in similar responses as optimization across all generations and simultaneous optimal selection in a male and female line resulted in greater response than optimal selection within a single line without crossbreeding. Results show that strategic use of information on over-dominant QTL can enhance crossbred performance without crossbred testing.     

Molecular phylogeny of Heritiera Ait on (Sterculiaceae), a tree mangrove: variations in RAPD markers and nuclear DNA content

Random amplified polymorphic DNA (RAPD) markers are used to estimate interspecific variation among mangrove and non-mangrove Heritiera fomes, H. littoralis and H. macrophylla. All the species have 2n = 38 chromosomes, with minute structural changes distinguishing the karyotype of each species. Significant variation of 4C DNA content occurs at the interspecific level. Interspecific polymorphism ranged from 14.09% between H. fomes and H. littoralis to 52.73% between H. fomes and H. macrophylla. H. macrophylla showed wide polymorphism in the RAPD marker with H. littoralis (51.23%) and H. fomes (52.73%). Two distinct RAPD products obtained from OPA-10 (1000 bp) and OPD-15 (900 bp) found characteristic molecular markers in H. macrophylla , a species from a non-mangrove habitat. H. macrophylla was more distantly related to H. fomes [genetic distance (1-F) = 0.305] than to H. littoralis [genetic distance (1-F) = 0.273]. H. littoralis was of a closer affinity to H. fomes [genetic distance (1-F) = 0.218] than to H. macrophylla.     

Segregation of infectious pancreatic necrosis resistance QTL in the early life cycle of Atlantic Salmon (Salmo salar)

In a previous study, three significant quantitative trait loci (QTL) associated with resistance to Infectious Pancreatic Necrosis (IPN) disease were identified by analysing challenge data from one sub-population of Landcatch Atlantic salmon (Salmo salar) smolt. While these QTL were shown to affect the resistance in seawater, their effect in freshwater was unknown. This study investigates the effect of these QTL on IPN resistance in salmon fry in freshwater. Twenty families with intermediate levels of IPN mortality were analysed from a freshwater challenge trial undertaken on a different sup-population of LNS salmon to that studied previously. Only the QTL from linkage group 21 (LG21) appeared to have a significant and large effect on resistance in freshwater; the same QTL was found to have the largest effect in seawater in the previous study. Variance component analysis showed a high heritability for the QTL: 0.45 ± 0.07 on the liability scale and 0.25 ± 0.05 on the observed scale. In a family where both parents were segregating for the QTL, there was a 0% vs. 100% mortality in homozygous offspring for resistant and susceptible QTL alleles. The finding that the same QTL has major effect in both freshwater and seawater has important practical implications, as this will allow the improvement of resistance in both phases through marker assisted selection by targeting this QTL. Moreover, the segregation of the LG21 QTL in a different sub-population gives further evidence of its association with IPN-resistance.     

Use of live Saccharomyces cerevisiae cells as a biological response modifier in experimental infections

Abstract A short-term oral administration of live Saccharomyces cerevisiae cells, strain Sillix Hansen DSM 1883, resulted in enhanced resistance of mice toward infections with K. pneumoniae, S. pneumoniae and S. pyogenes A produced by intranasal inoculation. Yeast pre-treatment also increased the efficacy of antibiotic therapy in bacterial infections and of antiviral drugs in viral infections. Yeast treatment of animals stimulated phagocytosis, activated the complement system and induced interferon which are likely to represent the main mechanisms of action whereby pretreatment of mice with live S. cerevisiae cells increases resistance to infection. It is concluded that preventive administration of live Saccharomyces cerevisiae cells should be used for increasing resistance to bacterial infections, in particular of the respiratory tract, or to viral infections, as well as an adjunct to antibiotic and antiviral drug therapy.     

Limitations of Chromogranin A in clinical practice

Context: Usefulness of circulating Chromogranin A (CgA) for the diagnosis of neuroendocrine tumors (NEN) is controversial. The aim of the present study was to assess the actual role of this marker as diagnostic tool. Methods: Serum blood samples were obtained from 42 subjects affected with NEN, 120 subjects affected with non-endocrine neoplasias (non-NEN) and 100 non-neoplastic subjects affected with benign nodular goitre (NNG). Determination of CgA was performed by means of immunoradiometric assay. Results: The CgA levels among NEN-patients were not significantly different from NNG and non-NEN subjects. The Receiver operating characteristic (ROC) curves analysis failed to identify a feasible cut-off value for the differential diagnosis between NEN and the other conditions. Conclusion: Serum CgA is not helpful for the first-line diagnosis of NEN.     

The physical map ofMus musculus chromosome 11 reveals evolutionary relationship with different syntenic groups of genes inHomo sapiens

Summary The physical localization of sequences homologous to three cloned genes was determined by in situ hybridization to metaphase chromosomes. Previous work had assigned the skeletal myosin heavy chain gene cluster (Myh), the functional locus for the cellular tumor antigen p53 (Trp53-1), and the cellular homologue of the viral erb-B oncogene (Erbb) toMus musculus chromosome 11 (MMU11). Our results provide regional assignments ofMyh andTrp53-1 to chromosome bands B2C, and ofErbb to bands A1A4. Taken together with in situ mapping of three other loci on MMU 11 (Hox-2 homeobox-containing gene cluster, theSparc protein, and theColla-1 collagen gene), which have been reported elsewhere, these data allowed us to construct a physical map of MMU11 and to compare it with the linkage map of this chromosome. The map positions of the homologous genes on human chromosomes suggest evolutionary relationships of distinct regions of MMU11 with six different human chromosome arms: 1p, 5q, 7p, 16p, 17p, and 17q. The delineation of conserved chromosome regions has important implications for the understanding of karyotype evolution in mammalian species and for the development of animal models of human genetic diseases.     

Mucosal epithelial cells and Langerhans cells are targets for infection by the immunosuppressive type D retrovirus simian AIDS retrovirus serotype 1

Simian acquired immune deficiency syndrome (SAIDS) caused by the type D retrovirus SRV-1 results in opportunistic infections and a spectrum of oral lesions similar to those seen in humans with AIDS. To better understand the pathogenesis of these oral lesions we have retrospectively examined the oral mucosa from ten rhesus monkeys that died with SAIDS and prospectively examined the oral mucosa of ten additional animals inoculated with SRV-1 to determine at what time, and in what cells SRV-1 infection of the oral mucosa occurs. Using single and double label immunohistologic techniques, and electron microscopy we detected SRV-1 in clusters of oral epithelial cells and rare Langerhans cells as early as 1 month postinoculation.     

EMA,an epithelial membrane-associated antigen during early development and morphogenesis ofXenopus laevis

Summary We raised monoclonal antibodies against a membrane fraction ofXenopus neurulae in order to detect tissue-specific cell-surface markers. Here we describe a monoclonal antibody that recognizes an epithelial membrane-associated antigen (EMA) in immunohistological stainings. The tissue-specific and membrane-associated antigen detected in immunohistological stainings could serve as useful marker in epithelium differentiation and membrane organization of the early embryo. In tadpoles and adults EMA was found in specific epithelial tissues derived from different germ layers such as kidney, skin, gut, pancreas, epiphysis and choroid plexus. In the cleaving embryo this antibody stained newly formed membranes between blastomeres from the two-cell stage onwards. Cytoplasmic staining in large oocytes and early embryos was also observed. The possibility that the cytoplasmic signal represents a maternal store of membrane material is discussed.