Ruptured fission yeast walls

Distributions of rupture sites of fission yeast cells ruptured by glass beads have been related to a new morphometric analysis. As shown previously (Johnson et al.,Cell Biophysics, 1995), ruptures were not randomly distributed nor was their distribution dictated by geometry, rather, ruptures at the extensile end were related to cell length just as the rate of extension is related to cell length. The extension patterns of early log, mid-log, late log, and stationary phase cells from suspension cultures were found to approximate the linear growth patterns of Kubitschek and Clay (1986). The median length of cells was found to decline through the log phase in an unbalanced manner.     

A survey for Cyclospora spp. in Kenyan primates, with some notes on its biology.

From March 1999 through August 2000, 511 stool samples collected from 11 different primate species in 10 geographically distinct locations in Kenya, East Africa, were screened for the presence of Cyclospora spp. oocysts. Positive samples (43/102, 42%) were identified in vervet monkeys (Cercopithecus aethiops) in 4 of 4 locations; 19/206 (9%) in yellow and olive baboons (Papio cynocephalus, P. anubis, respectively) in 5 of 5 locations; and 19/76 (25%) in black and white colobus monkeys (Colobus angolensis, C. guereza, respectively) from 2 of 3 locations. DNA sequences obtained from 18 S rRNA coding regions from respective subsets of these positive samples were typed as Cyclospora cercopitheci (samples from Cercopithecus aethiops). Cyclospora papionis (samples from Papio cynocephalus and P. anubis), and Cyclospora colobi (samples from Colobus angolensis and C. guereza). Cyclospora oocysts were not detected in samples collected from patas, highland sykes, lowland sykes, blue sykes, DeBrazza, or red-tailed monkeys. A coded map showing the geographic location of the collected samples is given. Stool samples from 1 troop of vervet monkeys were collected over a 12-mo period. Positive samples ranged between 21 and 63%. These results suggest that there is no strongly marked seasonality evident in Cyclospora infection in monkeys as has been noted in human infection. This is further confirmed by the recovery of positive samples collected from vervet monkeys, baboons, and colobus monkeys at all times of the year during this survey. This absence of seasonality in infection is especially notable because of the extreme weather patterns typical of Kenya, where marked rainy and dry seasons occur. A second noteworthy observation is that the striking host specificity of the Cyclospora species initially described was confirmed in this survey. Baboons were only infected with C. papionis, vervet monkeys with C. cercopitheci, and colobus monkeys with C. colobi, despite geographic overlaps of both the monkey and parasite species and wide geographic distribution of each parasite and monkey host.     

Phosphate effects in the fermentation of α-amylase by Bacillus amyloliquefaciens

Summary The effects of phosphate on -amylase fermentation byBacillus amyloliquefaciens were investigated. It was observed through batch culture that optimal phosphate level which maximizes -amylase biosynthesis exists. High concentration of phosphate level promotes maltose uptake and growth of the microorganism, while high maltose uptake rate in the microorganism at the same time represses the enzyme biosynthesis presumably due to catabolite repression inside the microorganism. In continuous cultivation, a steady state of -amylase biosynthesis was obtained by maintaining phosphate level at a certain level. In fed-batch culture, by intermittant feeding of phosphate as well as maltose, higher activity of -amylase in the broth was obtained compared to the result from single nutrient feeding.     

Two subunits of mannose permease, II-PMan and II-MMan, of Escherichia coli mediate coliphage N4 infection

Mutant strains of Escherichia coli that lack one or all of the intact components of mannose permease do not support the growth of phage N4. Complementation experiments using three recombinant plasmids containing DNA fragments coding for the subunits of mannose permease revealed that among the three component subunits, II-PMan and II-MMan alone are sufficient to confer N4 sensitivity.     

Exciton interactions in synthetic porphyrin dimers

The Soret absorption spectra of six synthetic rigid porphyrin dimers whose crystal structures have been determined are simulated using simple exciton theory. The objective is to test the validity of the point dipole and associated approximations; the electronic interaction parameters are thus calculated using data obtained from the monomer spectra, with no adjustable parameters. Satisfactory agreement between theory and experiment is obtained for one class of dimers but not for a second. This poses a challenge for semiempirical electronic structure methods as to whether improvements over the point dipole calculations can be obtained.     

N-linked oligosaccharide changes with oncogenic transformation require sialylation of multiantennae

Glycopeptides derived from NIH 3T3 fibroblasts and these cells transformed by transfection with human DNA containing oncogene H-ras were analyzed by 500-MHz 1H-NMR spectroscopy and binding to immobilized lectins. The cells were metabolically labeled with D-[3H]glucosamine or L-[3H]fucose and the glycopeptides included in Bio-Gel P-10 (Mr 5000-3500) were separated into neutral and charged fractions on DEAE-cellulose. The major portion (80%) of these [3H]fucose glycopeptides from the non-transformed NIH 3T3 fibroblasts were neutral or contained one or two charged residues, whereas 90% of the glycopeptides from the transformed cells contained two or more charged residues. The structure of the predominant neutral glycopeptide from the non-transformed NIH 3T3 cells was determined by 1H-NMR spectroscopy to be tetraantennary containing terminal Gal alpha 1----3. (formula; see text) This structure was verified by binding to the immobilized alpha-Gal-specific lectin, Griffonia simplicifolia I and leukoagglutinating phytohemagglutinin from Phaseolus vulgaris (L-PHA), which binds certain tri- or tetraantennary glycopeptides. In contrast, the structure derived by NMR spectroscopy of one of the predominant charged glycopeptides from the transformed cells was triantennary containing terminal NeuNAc alpha 2----3 in addition to Gal alpha 1----3. (formula; see text) In attempting to verify this structure by lectin-binding properties it was found that removal of NeuNAc alpha 2----3 reduced the affinity to L-PHA - agarose. The other major glycopeptides of the transformed cells which were more charged also cotained NeuNAc alpha 2----3 but no NeuNAc alpha 2----6 or Gal alpha 1----3. A tentative structure was proposed for the major glycopeptide of the first charged class from NIH 3T3 cells on the basis of lectin-binding properties and the NMR spectrum which showed, in addition to NeuNAc alpha 2----3, the presence of NeuNAc alpha 2----6 and Gal alpha 1----3. On the basis of the NMR spectrum and other results, it is concluded that the presence of tetraantennary oligosaccharides are not sufficient for the transformed oligosaccharide phenotype. Rather, the tri- or tetraantennae must be sialylated in alpha 2----3 linkage, on more than one antennae, when properties of transformation are expressed in NIH 3T3 cells. Prior to transformation the tetraantennary oligosaccharides of these cells are terminated in alpha-Gal residues, whereas after transformation alpha-Gal residues appear to be replaced by NeuNAc alpha 2----3.(ABSTRACT TRUNCATED AT 400 WORDS)     

Double-stranded RNA unwinding and modifying activity is detected ubiquitously in primary tissues and cell lines.

A double-stranded RNA unwinding and modifying activity was found to be present in a wide range of tissues and cell types. The level of activity did not vary significantly with respect to the state of cell differentiation, cell cycle, or transformation. Thus, the unwinding and modifying activity, localized in the nucleus in somatic cells and capable of converting many adenosine residues to inosine, appears to be one of the housekeeping genes.