Search for Drosophila genes encoding a conserved domain present in the achaete-scute complex and myc proteins

Summary Several genes of the achaete-scute complex (ASC) of Drosophila melanogaster encode a 60 amino acids long conserved domain which shares a significant homology with a region of the vertebrate myc proteins. Based on these results, the existence of a family of Drosophila genes that would share both this conserved domain and the neurogenic function of the AS-C has been postulated. To test this proposal, we have searched a D. melanogaster genomic library with a probe that encodes the conserved domain. Only under very low stringency hybridization conditions, clones not belonging to the AS-C cross-hybridized with the probe. Those that gave the strongest signals were characterized. Sequencing of the cross-hybridizing regions showed that they had no significant homology with the conserved domain, the sequence similarity extending at the most for 37 nucleotides. Although our results do not conclusively disprove the existence of a family of AS-C-like genes, they indicate that the conservation of the domain would be lower than that found for shared motifs in other families of Drosophila developmental genes.     

Expression of human lactotransferrin receptors in phytohemagglutinin-stimulated human peripheral blood lymphocytes. Isolation of the receptors by antiligand-affinity chromatography

In the resting rate, the human peripheral blood lymphocytes did not show detectable surface and intracellular receptors for human lactotransferrin. However, both types of lactotransferrin receptors were expressed during stimulation of lymphocytes with phytohemagglutinin. The appearance of receptors was time-dependent and the number of receptors reached a plateau after at least two days of mitogen stimulation. These results suggest that the presence of surface receptors on mitogen-stimulated lymphocytes is not consecutive to a modification of subcellular distribution but to an induction of biosynthesis of the receptors. As measured by incorporation of [3H]thymidine into DNA, addition of human lactotransferrin in a serum-free medium increased the proliferative activity of phytohemagglutinin-stimulated lymphocytes. Optimal enhancement of [3H]thymidine incorporation was obtained by adding 30% iron-saturated lactotransferrin at a concentration of 0.17 microM. Therefore, the role of lactotransferrin in the response of lymphocytes to mitogen stimulation appears to be similar to that previously described for serotransferrin. The lactotransferrin receptor was visualized using 125I-labeled lactotransferrin on nitrocellulose paper after electroblotting of the Triton X-100 extract of the phytohemagglutinin-stimulated lymphocytes as two protein bands of 100 and 110 kDa molecular mass. Purification of the lactotransferrin receptor from the Triton-X-100-soluble extract of stimulated lymphocytes was performed by antiligand-affinity chromatography. The binding of lactotransferrin to the purified receptors was reversible and dependent on concentration and pH.     

A differential scanning calorimetric study of the binding of sulfate ion and of Cibacron blue F3GA to yeast phosphoglycerate kinase

In continuation of earlier work [Hu, C. Q., & Sturtevant, J.M. (1987) Biochemistry 26, 178-182], differential scanning calorimetry has been employed in a study of the effects on the thermal denaturation of yeast phosphoglycerate kinase of two inhibitors of the enzyme, sulfate ion and the dye Cibracron blue F3GA. Sulfate ion, as is usual with ligands that dissociate during unfolding of the host protein, raises t1/2, the temperature of half-completion of the denaturation, has only a modest effect, stemming from the enthalpy of dissociation of the ligand, on the enthalpy of denaturation, and has little or no effect on the heat capacity change resulting from denaturation. In sharp contrast, Cibacron blue F3GA lowers t1/2 and drastically decreases both the enthalpy and heat capacity changes due to denaturation. The DSC results with sulfate ion are consistent with previous kinetic data [Scopes, R. K. (1978) Eur. J. Biochem. 91, 119-129; Khamis, M. H., & Larsson-Raznikiewicz, M. (1981) Biochim. Biophys. Acta 657, 190-194], which indicate two binding sites for sulfate ion at one of which the ligand acts as a competitive inhibitor. The results with Cibacron blue F3GA indicate that the dye induces a major destabilizing structural change in the enzyme in addition to rendering it enzymically inactive.     

The breeding biology of the WheatearOenanthe oenanthe in South Sweden during three contrasting years

Summary The breeding phenology, territory size, egg dimensions, clutch size, nestling growth and reproductive success of a dense population of WheatearsOenanthe oenanthe was studied on the island of Öland, S. Sweden during the years 1985–1987. The 1987 season was exceptionally cold and rainy, 1986 had the warmest and driest conditions, while 1985 was intermediate with respect to weather. Cold, windy and rainy weather was associated to prolonged incubation, greater intervals between first and replacement clutches, prolonged nestling growth, lower fledging condition, increased starvation and increased predation. Large clutches were laid earlier in the season and contained relatively larger eggs than small clutches. Incubation periods decreased with clutch size. Female size was positively correlated with egg size and with clutch size. The last egg laid in a clutch had a tendency to be heavier than eggs laid previously, especially in large clutches. Nestling starvation increased with brood size in 2 years.

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Zusammenfassung 1985–1987 wurden Phänologie, Siedlungsdichte, Eimaße, Gelegegröße, Jungenwachstum und Bruterfolg einer Population des Steinschmätzers auf der südschwedischen Insel Öland untersucht. 1987 waren die Lufttemperaturen besonders niedrig und die Niederschläge sehr hoch. Der Sommer 1986 wies dagegen die höchsten Temperaturen und niedrigsten Niederschläge der 3 Jahre auf. Kaltes, windiges und regnerisches Wetter war mit längerer Brütezeit, längeren Intervallen zwischen Erst- und Ersatzbruten, langsamerem Jungenwachstum, schlechterer Kondition der ausfliegenden Jungen und höheren Verlusten durch Verhungern und Beutefeinde korreliert. Die Gelegegröße nahm mit dem Legedatum ab; die größten Gelege hatten im Mittel größere Eier. Die Bebrütungszeit nahm mit der Gelegegröße ab. Größere Weibchen legten größere Eier und zeigten Tendenz, größere Gelege zu produzieren. Die zuletzt gelegten Eier waren meist die schwersten, besonders in großen Gelegen. Ausfälle durch Verhungern stiegen in 2 Jahren mit der Brutgröße.

     

抗阿特拉津转基因大豆植株后代的遗传分析

本试验用阿特拉津溶液涂抹、荧光诱导动力学检测、分子杂交等方法对抗阿特拉津转基因大豆植株的后代进行了鉴定,在第二代及第三代中检测到了抗性基因的存在,表明从龙葵中得到的此抗阿特拉津 psbA 基因不仅能导人大豆叶绿体基因组中获得表达,而且可以遗传到后代。