Chromosomal location and molecular mapping of a tan spot resistance gene in the winter wheat cultivar Red Chief

The winter wheat cultivar Red Chief has been identified as the wheat cultivar most resistant toPyrenophora tritici-repentis (Ptr). This study was undertaken to determine the inheritance, chromosomal location and molecular mapping of a tan spot resistance gene in Red Chief. χ² analysis of the F₂ segregation data of the hybrids between 21 monosomic lines of the susceptible wheat cultivar Chinese Spring and the resistant cultivar Red Chief revealed that tan spot resistance in cv. Red Chief is controlled by a single recessive gene located on chromosome 3A. Linkage analysis using SSR markers in the Red Chief/Chinese Spring F2 population showed that thetsr4 gene is clustered in the region aroundXgwm2a, on the short arm of chromosome 3A. This marker has also been identified as the closest marker to thetsr3 locus on chromosome 3D in synthetic wheat lines. Validation analysis of this marker for thetsr3 andtsr4 genes using 28 resistant and 6 susceptible genotypes indicated that the 120 bp allele (thetsr3 gene) specific fragment was observed in 11 resistant genotypes, including the three synthetic lines XX41, XX45 and XX110, while the 130 bp allele was amplified only in cv. Red Chief and Dashen.Xgwm2a can be used to trace the presence of the target gene in successive backcross generations and pyramiding of thetsr3 &tsr4 genes into a commonly grown and adaptable cultivar.     

Direct monitoring of capillary perfusion following normovolemic hemodilution in an experimental skin-flap model

The effects of normovolemic hemodilution on skin flap survival are studied in a recently developed skin-flap model (homozygous hairless mouse ear) in which nutritional capillary flow is monitored directly by means of intravital microscopy from the time of flap creation throughout the establishment of necrosis. Two diluting agents (dextran 60 and hydroxyethyl starch 200) are utilized. Our quantitative findings demonstrate that the amount of nonperfused tissue following flap creation in both the dextran (n = 23) and starch (n = 13) groups was significantly decreased as compared with controls (n = 19). Our qualitative observations suggest that improved hemorrheologic properties at the microcirculatory level are responsible for the observed decreased necrosis. Various mechanisms by which hemodilution may act to prevent necrosis are discussed.     

Nucleocytoplasmic distribution of snRNPs and stockpiled snRNA-binding proteins during oogenesis and early development in Xenopus laevis

The distribution of small nuclear ribonucleoprotein particles containing U snRNAs (U snRNPs) during oogenesis and early development in Xenopus was analyzed with a lupus antibody (anti-Sm) that reacts with snRNA-binding proteins. Fully grown oocytes and embryos prior to gastrulation were found to be relatively depleted of U snRNPs in their nuclei and to contain an excess of snRNA-binding proteins stored in the cytoplasm. During late blastula-early gastrula, or after microinjection of U snRNAs into the cytoplasm of a mature oocyte, the proteins migrate into the nucleus. Dot hybridization analysis showed that small previtellogenic oocytes already contain a maximal amount of U1 (and U2) snRNAs, which then decreases to about 20% of that value in fully mature oocytes, even though the cell's volume has increased enormously. Thus fully grown oocytes and eggs accumulate snRNA-binding proteins for use during early development, but this is not coupled with the accumulation of U snRNA.     

Les troponines

L’utilisation des dosages des troponines cardiaques ont participé à l’extension de la notion d’infarctus du myocarde et a permis au cardiologue l’identification et la stratification des patients présentant un syndrome coronarien aigu. Le développement de techniques d’immuno-dosages de ces protéines de structure du muscle cardiaque, ayant une grande spécificité, a rendu possible la détermination en routine de ces nouveaux marqueurs biochimiques.