Gibberellic acid flower formation and stem elongation in Silene armeria.

Several selected S. armeria lines differing in their reaction to GA3 were treated with GA3 at various concentrations under short-day (SD) or long-day conditions. With SD treatment one application of GA3 at high concentration (10 000 p.p.m. or greater) induced flower formation in certain lines. Stem elongation increased with GA3 concentration and with plant age and was much greater on flowering plants than on non-flowering ones. [For previous related work see HcA 41, 4400.]. (Abstract retrieved from CAB Abstracts by CABI’s permission

De taken des hoogleraars

Rede Wageninge

Molecular characterization of the HIV-1 gag nucleocapsid gene associated with vertical transmission

BACKGROUND: The human immunodeficiency virus type 1 (HIV-1) nucleocapsid (NC) plays a pivotal role in the viral lifecycle: including encapsulating the viral genome, aiding in strand transfer during reverse transcription, and packaging two copies of the viral genome into progeny virions. Another gag gene product, p6, plays an integral role in successful viral budding from the plasma membrane and inclusion of the accessory protein Vpr within newly budding virions. In this study, we have characterized the gag NC and p6 genes from six mother-infant pairs following vertical transmission by performing phylogenetic analysis and by analyzing the degree of genetic diversity, evolutionary dynamics, and conservation of functional domains. RESULTS: Phylogenetic analysis of 168 gag NC and p6 genes sequences revealed six separate subtrees that corresponded to each mother-infant pair, suggesting that epidemiologically linked individuals were closer to each other than epidemiologically unlinked individuals. A high frequency (92.8%) of intact open reading frames of NC and p6 with patient and pair specific sequence motifs were conserved in mother-infant pairs' sequences. Nucleotide and amino acid distances showed a lower degree of viral heterogeneity, and a low degree of estimates of genetic diversity was also found in NC and p6 sequences. The NC and p6 sequences from both mothers and infants were found to be under positive selection pressure. The two important functional motifs within NC, the zinc-finger motifs, were highly conserved in most of the sequences, as were the gag p6 Vpr binding, AIP1 and late binding domains. Several CTL recognition epitopes identified within the NC and p6 genes were found to be mostly conserved in 6 mother-infant pairs' sequences. CONCLUSION: These data suggest that the gag NC and p6 open reading frames and functional domains were conserved in mother-infant pairs' sequences following vertical transmission, which confirms the critical role of these gene products in the viral lifecycle

Een onderzoek naar de factoren, die ontijdige knolvorming bij vroege aardappels bepalen

Premature formation of tubers ('submarines') is a disturbance in the normal growth of a planted seed potato, resulting in the formation of some small daughter tubers without any aerial growth. In certain years losses may be heavy. The main cause is the formation of sprouts during storage which have to be removed. All factors preventing or reducing such sprout formation favour normal development: especially low temperature (above freezing-point) and light during storage, also late lifting of the seed tubers, large tubers, planting at higher temperature and in moist soil.The underlying process of premature tuber formation was assumed to be loss of water by removal of sprouts during storage, resulting in an increase in the concentration of solutes. Essentially the same occurs with normal tuber formation but there by an increase in assimilates. This concept was supported by plasmolysis studies in the hairs of the sprouts.</p

"Mij spreekt de blom een tale"

Rede. Wageningen, 9 maart 195