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61.
Accumulation of a Polyhydroxyalkanoate Containing Primarily 3-Hydroxydecanoate from Simple Carbohydrate Substrates by Pseudomonas sp. Strain NCIMB 40135 总被引:11,自引:6,他引:5
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Geoffrey W. Haywood Alistair J. Anderson David F. Ewing Edwin A. Dawes 《Applied microbiology》1990,56(11):3354-3359
A number of Pseudomonas species have been identified which accumulate a polyhydroxyalkanoate containing mainly 3-hydroxydecanoate monomers from sodium gluconate as the sole carbon source. One of these, Pseudomonas sp. strain NCIMB 40135, was further investigated and shown to accumulate such a polyhydroxyalkanoate from a wide range of carbon sources (C2 to C6); however, when supplied with octanoic acid it produced a polyhydroxyalkanoate containing mainly 3-hydroxyoctanoate monomers. Polymer synthesis occurred in batch culture after cessation of growth due to exhaustion of nitrogen. In continuous culture under nitrogen limitation up to 16.9% (wt/wt) polyhydroxyalkanoate was synthesized from glucose as the carbon source. The monomer units are mainly of the R-(−) configuration. Nuclear magnetic resonance studies confirmed the composition of the polymer. Differential scanning calorimetry suggested that the solvent-extracted polymer contained a significant proportion of crystalline material. The weight-average molecular weight of the polymer from glucose-grown cells was 143,000. 相似文献
62.
Frank J. Trueba Edwin A. van Spronsen Jan Traas Conrad L. Woldringh 《Archives of microbiology》1982,131(3):235-240
Two substrains of Escherichia coli B/r were grown to steady-state in batch cultures at temperatures between 22 and 42° C in different growth media. The size and shape of the cells were measured from light and electron micrographs and with the Coulter channelizer. The results indicate that cells are shorter and somewhat thicker at the lower temperatures, especially in rich growth media; cell volume is then slightly smaller. A lower temperature was further found to increase the relative duration of the constriction period. The shapes of the cell size distributions are indistinguishable, indicating that the pattern of growth of the cells is the same at all temperatures. The adaptation of the cells to a temperature shift lasted several generations, indicating that the morphological effects of temperature are mediated by the cell's physiology. 相似文献
63.
64.
Canavanine is an arginine analog which is widely used to inhibit proteolytic processing of viral polyproteins. Certain results obtained with canavanine have suggested that it may have other effects. Therefore, we examined the effects of canavanine on the cell-free synthesis of murine retrovirus proteins. It was found that the electrophoretic mobility of the major gag-related cell-free product of both Rauscher murine leukemia virus (R-MuLV) and Moloney murine sarcoma virus 124 (Mo-MuSV-124) RNA was dependent on the concentration of canavanine used during translation. As the canavanine concentration was increased up to 4 mM, the apparent size of the major gag-related polypeptide also increased from 65,000 (R-MuLV RNA) or 63,000 (Mo-MuSV-124 RNA) to approximately 80,000 daltons. Additional increases in the canavanine concentration up to 12 mM did not increase the size of the gag gene product beyond 80,000 daltons. This change in electrophoretic mobility appeared to be due to a substitution of canavanine for arginine residues in the polypeptides, not to a change in their actual size. If amber suppressor tRNA and canavanine were used together during translation of Mo-MuSV-124 RNA and Mo-MuLV RNA, the results were also in agreement with this proposal. Translation experiments done with ovalbumin mRNA and mengovirus 35S RNA indicated that canavanine incorporation caused a shift in the electrophoretic mobility of ovalbumin from 43,000 to 45,000 daltons and caused the appearance of two slightly larger polypeptides in the 155,000- and 115,000- dalton regions of the mengovirus RNA cell-free product. 相似文献
65.
Genetic polymorphism is found among the PIF (parotid isoelectric focusing variant) salivary proteins after separation by prolonged isoelectric focusing in pH 3.5–5.2 urea polyacrylamide slab gels subsequently stained for protein. Two PIF proteins are either present (PIF +) or absent (PIF –) from all salivas. The phenotypes are determined by autosomal inheritance of two alleles, PIF
+ and PIF
–. Gene frequencies in randomly collected samples show marked racial differences: among 148 whites, PIF
+ is 0.66 and PIF
– is 0.34; among 90 blacks, PIF
+ is 0.35 and PIF
– is 0.65; among 78 Chinese, PIF
+ is 0.56 and PIF
– is 0.44. Studies in 41 families including 129 children support the interpretation of control of PIF by a single autosomal locus. In 8 PIF+ × PIF– matings, there were 8 PIF– (6.34 expected) children. In 33 PIF+ × PIF+ matings, there were 7 PIF– (6.70 expected) children. Linkage studies indicate that PIF is closely linked to the proline-rich protein (PPP) gene complex (e.g., for six families, lod score at =0.00 of PIF/G1 is 3.58). In 107 randomly collected samples from whites, PIF is strongly associated with Db (x
1
2
=20.02; P<0.0001) and Gl (x
1
2
=12.58; P=0.0005) but not with Pr, Ps, Pm, and Pa proteins. These data (probably reflecting genetic disequilibrium) suggest that PIF may be closer to Db and G1 than to other identified loci of the PPP gene complex. The PPP gene complex includes at least seven genes (and probably more) that produce many acidic and basic proline-rich proteins, constituting about two-thirds of parotid salivary proteins that are thought to have important functions at the tooth surfaces.This study was supported by a grant from the National Institutes of Dental Research (DEO 3658-15). Paper No. 2435 of the Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706. 相似文献
66.
The polysaccharide of P. hymantophora has been shown to be composed of (1→4)-linked galactopyranosyl, (1→3)-linked galactopyranosyl, (1→3)-linked galactopyranosyl 2- and 4-sulphate and 2,6-disulphate residues. The (1→3)- and (1→4)-linked units are present in approximately equal amounts. The polysaccharide of P. hieroglyphica has been shown to possess (1→4)-linked galactopyranosyl, (1→3)-linked galactopyranosyl, and (1→3)-linked galactopyranosyl 2- and 4-sulphate residues. The (1→3)- and (1→4)-linked units are present in a 4:1 ratio. Both polysaccharides contain small proportions of non-reducing xylosyl end-groups. 相似文献
67.
68.
Analysis of Pleiotropism at the Dominant White-Spotting (W) Locus of the House Mouse: A Description of Ten New W Alleles 总被引:1,自引:0,他引:1
Characterization of the pleiotropic effects of ten new putative W locus mutations, nine co-isogenic and one highly congenic with the C57BL/6J strain, reveals a wide variety of influences upon pigmentation, blood formation and gametogenesis. None of the putative alleles, each of which is closely linked to Ph, a gene 0.1 cM from W, gave evidence of complementation with W39, a new allele previously shown to be allelic to Wv. All W*/W39 genotypes resulted in black-eyed-white anemics with reduced gametogenic activity.1 Homozygotes for seven of these mutations are lethal during perinatal life; anemic embryos have been identified in litters produced by intercross matings involving each of these alleles.—Phenotypes of mice of several mutant genotypes provide exceptions to the frequent observation that a double dose of dominant W alleles (e.g., W/Wv or W/W) results in defects of corresponding severity in each of the three affected tissues. One viable homozygote has little or no defect in blood formation, and another appears to have normal fertility. The phenotypes of these homozygotes support the conclusion that the three tissue defects are not dependent on each other for their appearance and probably do not result from a single physiological disturbance during the development of the embryo.—Although homozygosity for members of this series results in a wide range of phenotypes, the absence of complementation of any allele with W39, the close proximity of each mutant to Ph, and the fact that all alleles produce detectable (though sometimes marginal) defects in the same tissues affected by W and Wv, support the hypothesis that each new mutant gene is a W allele. 相似文献
69.
To determine the role of the maternal environment in the development of adult olfactory preferences, the young of two species of North American lemmings (Dicrostonyx groenlandicus and Lemmus trimucronatus) were reciprocally cross-fostered shortly after birth. In-fostered (reared by foster conspecific females) and non-fostered animals served as controls. When adult, subjects were tested for olfactory preferences in a free-choice Y-maze olfactometer. When compared to controls, cross-fostered animals showed increased preference for heterospecific odour. This effect was stronger for males than for females. These results suggest that adult species-specific odour preferences are learned during the neonatal period. 相似文献
70.
Genetic polymorphism of the major glycoprotein (Gl) found in parotid saliva is determined by autosomal inheritance of one unexpressed and four expressed alleles. This hypothesis is supported by studies in 41 white families including 146 children. For 143 randomly collected salivas from whites and 82 randomly collected salivas from blacks, maximum likelihood estimates of the gene frequencies are as follows: for whites, Gl
1=0.742, Gl
2=0.040, Gl
3=0.155, Gl
4=0.017, Gl
0=0.046; for blacks, Gl
1=0.459, Gl
2=0.050, Gl
3=0.337, Gl
4=0.044, Gl
0=0.110. There is strong evidence for linkage of Gl/Pr (seven families, lod score at =0 is 5.24) and Gl/Db (eight families, lod score at =0 is 4.45). The allelic products of Gl show evidence for linkage disequilibrium with the products of the Pr, Db, and Pa loci (P<0.0005). On the basis of varying degrees of linkage disequilibrium, Gl may be closer to Db than to Pr or Pa and on the outside of Db with respect to Pr or Pa. Amino acid analyses of Gl 1 and Gl 4 proteins show strong resemblances in composition to the major basic glycoprotein and the acidic proline-rich proteins of parotid saliva described by other workers. The polymorphic forms of the Gl proteins show microheterogeneity due to variability in charge and molecular weight. The electrophoretic polymorphism appears to be determined by apparent differences in molecular weights between the Gl proteins.This study was supported by a grant from the National Institutes of Dental Research (DEO 3658-12) and in part by NIH Grant GM 15422 and NIH Training Grant GM 00398. Paper No. 2242 of the Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706. 相似文献