NMR detection of structures in the HIV-1 5'-leader RNA that regulate genome packaging

The 5'-leader of the HIV-1 genome regulates multiple functions during viral replication via mechanisms that have yet to be established. We developed a nuclear magnetic resonance approach that enabled direct detection of structural elements within the intact leader (712-nucleotide dimer) that are critical for genome packaging. Residues spanning the gag start codon (AUG) form a hairpin in the monomeric leader and base pair with residues of the unique-5' region (U5) in the dimer. U5:AUG formation promotes dimerization by displacing and exposing a dimer-promoting hairpin and enhances binding by the nucleocapsid (NC) protein, which is the cognate domain of the viral Gag polyprotein that directs packaging. Our findings support a packaging mechanism in which translation, dimerization, NC binding, and packaging are regulated by a common RNA structural switch.     

Selection in vitro for erucic-acid content in segregating populations of microspore-derived embryoids of Brassica napus

Microspore culture of Brassica napus under optimized conditions leads to the regeneration of microspore-derived embryoids that, at the late cotyledonary stage, contain large amounts of storage lipids, equal or similar in composition to those found in seeds of the homozygous donor plants. At that stage, the microspore-derived embryoids are large enough to allow the dissection of one cotyledon under aseptic conditions and the determination of its fatty-acid composition. The remaining part of the embryoid can be cultured further and regenerated to give a plant. This offers the possibility of early selection for fatty-acid composition in segregating populations of microspore-derived embryoids. In order to verify this hypothesis, embryoids were generated from microspores of F| plants derived from a cross between doubled haploid lines of the low-erucicacid cv. ‘Duplo’ and the high-erucic-acid cv. ‘Janetzki’. The contents of eicosenoic acid (C20: 1) and erucic acid (C22: 1) in the cotyledons and in the seeds derived from plants regenerated from the remaining parts of the embryoids were highly correlated (rs = 0.85**, P = 0.01). This indicates that, in breeding programmes for high erucic acid, the majority of the microspore—derived embryoids can be discarded at an early stage in vitro. Only microspore-derived embryoids with a high content of C20: 1+C22:1 in the cotyledons need to be transferred to the greenhouse. This report also deals with the addition of abscisic acid (ABA) to the embryoid culture medium to increase the correlation, and discusses the possible application of this system for the selection of high-oleic or low-linolenic types in corresponding microspore-derived embryoid populations.     

Variation over time and environments in resistance to Erysiphe graminis hordei in samples from a barley germplasm collection

Summary Twenty carnation genotypes of diverse origin were planted in September and were kept under an 8h day and a light intensity of 15 W/m² visible radiation in a phytotron from 30 November to 24 February. Long photoperiods (24 h; LD) were applied in December-January for 25 days. In addition to flowering dates of individual shoots, records wer kept on shoot development (number of visible leaf pairs) on four dates: (1) six weeks after pinching, (2) at the beginning of the LD treatment in December, (3) when plants were transferred from the phytotron to the glasshouse in February and (4) at the time of flowering of individual shoots.The genetic variation in number of visible leaf pairs on each of these dates, in relation to shoot position and rate of unfolding of leaf pairs, was analysed.On the basis of these analyses, the between and within-genotype variation in time of flowering, yield distribution and LD response could be, at least partly, related to variation in the above-mentioned parameters. It was established that relevant genetic variation exists in (1) the initial development of the axillary bud from which a primary shoot is produced after pinching; (2) the rate of leaf unfolding; (3) the minimum number of leaf pairs required for flower initiation and (4) the within-plant variation in the above three characters in relation to shoot position.     

Physiologische und ökologische Forschungen als Grundlagen praktischer Maßnahmen

Ohne Zusammenfassung Biologische Reichsanstalt für Land- und Forstwirtschaft     

Über die Dauerwirkung des Mottenschutzes durch Eulan

Ohne Zusammenfassung Mit 9 Abbildungen     

Über Sperlingsschäden an Pflaumen

Ohne Zusammenfassung Mit 1 Abbildung.     

Zerstörungen von Papierwaren durch Silberfischchen (Lepismatiden) und deren Bekämpfung

Ohne Zusammenfassung Mit 9 Abbildungen.     

Über die Dauerwirkung des Mottenschutzes durch Eulan

Ohne Zusammenfassung Mit 6 Abbildungen.     

Über die Widerstandsfähigkeit des Kornkäfers

Ohne Zusammenfassung