A tissue culture technique for rapid clonal propagation and storage under minimal growth conditions of Musa (Banana and plantain)

A tissue culture technique for rapid clonal propagation and storage under minimal growth conditions is presented in this paper. Shoot-tip cultures of Musa cultivars (both banana and plantain) are induced by culturing small excised shoot apices on modified MS semisolid medium supplemented with various concentrations and combinations of auxins and cytokinins. The effects of cytokinin concentration in the medium as well as the genotypic configuration of the cultivars on the rate of shoot-bud proliferation have been tested. The established shoot-tip cultures grown on modified MS semisolid medium supplemented with IAA (0.18 mg/l) and BA (2.30 mg/l) have been successfully stored at 15°C with 1000 lux light intensity up to 13–17 months depending on the cultivar. The cultivars tested in the present investigation seem to vary in their ability to withstand minimal growth temperature.Abbreviations BA Benzyladenine - IAA Indoleacetic acid - IBA Indolebutyric acid - MS Murashige and Skoog     

SOME CORTICOLOUS ALGAE OF MCMINN COUNTY,TENNESSEE, U.S.A.1

Eisrhty-one unialgal isolates comprising 10 genera (Chlorophygeae, Cyanophyceae, Xanthophyceae) were cultured from samples of tree bark scrapings removed from 5 species of trees on the campus of Tennessee Wesleyan College in Athens, Tennessee, U.S.A.     

ANG II AT1 and AT2 receptors both inhibit bFGF-induced proliferation of bovine adrenocortical cells

Angiotensin II(ANG II) has long been known for its pressor and growth-promotingeffects, which are both mediated by theAT₁ receptor. By contrast, theAT₂ receptor has recently beenreported to mediate inhibition of proliferation through as yetundefined mechanisms. We report here that in bovine adrenal fasciculata cells ANG II by itself does not affect growth but inhibits basic fibroblast growth factor (bFGF)-induced DNA synthesis and blocks thecells in G₁ phase. Consistent withthis, ANG II inhibits cyclin D₁ expression and cyclinD₁-associated kinase activity. Theantimitogenic effect of ANG II is partly mimicked by theAT₂-selective agonist CGP-42112.It is also blocked partly and in an additive fashion by theAT₁- andAT₂-selective antagonists losartanand PD-123319, indicating the contribution of both receptor subtypes tothis response. AT₁-dependentantiproliferation is selectively blocked by the cyclooxygenaseinhibitor indomethacin and restored by prostaglandin E₂, whereasAT₂-receptor-mediated inhibitionof growth is suppressed by the tyrosine phosphatase inhibitorsorthovanadate and bpV(pic). Both pathways are, however,pertussis toxin sensitive. We hypothesize that, in fasciculatacells, the AT₁ receptor inhibitsbFGF-induced proliferation by stimulating prostaglandin synthesis,whereas the AT₂ receptor mediatesits effect through a pathway that requires protein tyrosine phosphataseactivation.

     

Population Structure and Genetic Diversity of Common Bean Accessions from Brazil

Plant Molecular Biology Reporter - Brazil can be considered a secondary center of common bean diversification (Phaseolus vulgaris L.), and the landraces grown throughout Brazil are valuable sources...     

Sirtuin inhibition increases the rate of non-homologous end-joining of DNA double strand breaks

Sirtuins (type III histone deacetylases) are an important member of a group of enzymes that modify chromatin conformation. We investigated the role of sirtuin inhibitor, GPI 19015, in double strand break (DSB) repair in CHO-K1 wt and xrs-6 mutant cells. The latter is defective in DNA-dependent protein kinase (DNA-PK)-mediated non-homologous end-joining (D-NHEJ). DSB were estimated by the neutral comet assay and histone gammaH2AX foci formation. We observed a weaker effect of GPI 19015 treatment on the repair kinetics in CHO wt cells than in xrs6. In the latter cells the increase in DNA repair rate was most pronounced in G1 phase and practically absent in S and G2 cell cycle phases. The decrease in the number of histone gammaH2AX foci was faster in xrs6 than in CHO-K1 cells. The altered repair rate did not affect survival of X-irradiated cells. Since in G1 xrs6 cells DNA-PK-dependent non-homologous end-joining, D-NHEJ, does not operate, these results indicate that inhibition of sirtuins modulates DNA-PK-independent (backup) non-homologous end-joining, B-NHEJ, to a greater extent than the other DSB repair system, D-NHEJ.     

Eine Theorie über das Spektrum von Selbstlauten

Zusammenfassung Zweck des vorliegenden Aufsatzes ist es, die Form des Spektrums von Sprechsignalen, wie z.B. von Selbstlauten, zu erklären.

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Summary The aim of this paper is to explain from the mathematical point of view the vowels spectrum.

     

Improved confocal characterization of targets in nuclei of cytogenetic preparations

OBJECTIVE: To show that cellular preparations requiring depth analysis of different domains stained by molecular cytogenetic methods (fluorescence in situ hybridization and primed in situ) can be improved by regularized factor analysis of medical image sequences (FAMIS) to isolate fluorescent probes by means of intensity depth profiles of fluorochromes, to track relevant DNA sequences (cosmids and centromeres) in cell nuclei during interphase and to improve the use of cytogenetic techniques resulting in flat preparations of whole cells that are assumed to preserve probe access to their targets. STUDY DESIGN: 3D sequences of images obtained by depth displacement in a confocal microscope were first analyzed by the FAMIS algorithm, which provides factor curves. Factor images then resulted from regularization methods that improve signal/noise ratio while preserving target contours. RESULTS: Factor curves and regularized factor images helped analyze targets inside nuclei. CONCLUSION: It is possible to process preparations containing numerous spots (even when they are on different planes) to differentiate stained targets, to investigate depth differences and to improve visualization and detection.