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D W Hilbert

Publications and source records attributed to D W Hilbert.

4 recordsLinked to original sources
PubMed2002

Data requirements and data sources for biodiversity priority area selection.

The data needed to prioritize areas for biodiversity protection are records of biodiversity features - species, species assemblages, environmental classes - for each candidate area. Prioritizing areas means comparing candidate areas, so the data used to make such comparisons should be comparable in quality and quantity. Potential sources of suitable data include museums, herbariums and natural resource management agencies. Issues of data precision, accuracy and sampling bias in data sets from such sources are discussed and methods for treating data to minimize bias are reviewed.

Animals↗
PubMed2000

The putative DNA translocase SpoIIIE is required for sporulation of the symmetrically dividing coccal species Sporosarcina ureae.

The spoIIIE gene of Sporosarcina ureae encodes a 780-residue protein, showing 58% identity to the SpoIIIE protein of Bacillus subtilis, which is thought to be a DNA translocase. Expression of the S. ureae spoIIIE gene is able to restore sporulation in a B. subtilis spoIIIE mutant. Inactivation of the S. ureae spoIIIE gene blocks sporulation of S. ureae at stage III. Within the limits of detection, the sporulation division in S. ureae shows the same symmetry, or near symmetry, as the vegetative division (in contrast to the highly asymmetric location of the sporulation division for B. subtilis), and so it is inferred that SpoIIIE facilitates chromosome partitioning during sporulation, even when the division is not grossly asymmetric. It is suggested that chromosome partitioning lags behind division during sporulation but not during vegetative growth.

Bacillus subtilis↗
PubMed2000

The chromosomal location of the Bacillus subtilis sporulation gene spoIIR is important for its function.

Formation of the asymmetrically located septum during sporulation of Bacillus subtilis results in enclosure of the origin-proximal 30% of the chromosome in the prespore compartment. The rest of the chromosome is then translocated into the prespore from the mother cell. Transcription of spoIIR is initiated in the prespore by RNA polymerase containing sigma(F) soon after the septum is formed. The SpoIIR protein is required for the activation of the transcription program directed by sigma(E) in the mother cell. The spoIIR locus is located at 324 degrees, near the origin of replication (0/360 degrees ). We show here that movement of spoIIR to 28 degrees had little effect on sporulation. However, movement to regions not in the origin-proximal part of the chromosome substantially reduced sporulation efficiency. At 283 degrees sporulation was reduced to less than 20% of the level obtained when spoIIR was at its natural location, and movement to 190 degrees reduced sporulation to about 6% of that level. These positional effects were also seen in the transcription of a spoIIR-lacZ fusion. In contrast, movement of other spo-lacZ fusions from 28 degrees to 190 degrees had little effect on their expression. These results suggest that spoIIR is the subject of "positional regulation," in the sense that the chromosomal position of spoIIR is important for its expression and function.

Bacillus subtilis↗