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41.
D. M. Lonsdale R. L. Allen D. Belostotsky T. K. Ghose A. J. Harvey H. J. Rogers S. J. Tebbut M. Trick 《Plant cell reports》1995,15(1-2):154-158
Summary The promoters of a tobacco actin gene, a tobacco pectate lyase, a tobacco and maize polygalacturonase and aBrassica S-locus related gene have been fused to the-glucuronidase reporter gene and their activities determined by biolistic transient assay in tobacco pollen. In stably transformed tobacco all the transgenes with the exception of Cauliflower Mosaic Virus-35S--glucuronidase appear to express efficiently in maturing pollen. Transient assay analysis showed that the tobacco pectate lyase and the polygalacturonase constructs were 8x more active than the tobacco actin construct, and that the tobacco polygalacturonase construct was some 33x more active than the maize polygalacturonase construct. Constructional manipulations that altered the lengths of the 5-untranslated leaders including one which resulted in the removal of a 490 bp leader intron had little effect on the observed level of expression. However, the alteration of the context of the ATG from A/TnnATGG to CnnATGT resulting in a 70% reduction in the observed levels of activity, was obtained with the pectate lyase and polygalacturonase promoters. An identical reductional was also observed in transgenic plant populations transformed with the polygalacturonase transgenes.Abbreviations GUS
-glucuronidase
- LUC
luciferase
- NosTer
nopaline synthase terminator
- CaMV
Cauliflower Mosaic Virus
- UTL
untranslated leader
- PCR
polymerase chain reaction
- PG
polygalacturonase
- Npg
tobacco polygalacturonase
- Pl
pectate lyase
- Ac
actin 相似文献
42.
Summary
Trichoderma reesei Rut-C30 was found to produce extracellular lactase when grown on lactose medium. Maximum enzyme levels in continuous culture were observed at dilution rates (D) between 0.02 and 0.027 hr-1. The enzyme productivity reached 27.3 U/L hr at D = 0.027 hr-1. Lactase synthesis appears to be inducible and subject to catabolite repression. Optimal growth temperature and pH for enzyme production were 28°C and pH 5. Maximum enzyme activity was observed at 63°C and pH 4.6. The apparent Km, based on the nitrophenyl-galactopyranoside assay was estimated as 0.4 mM. The enzyme is suitable for lactose hydrolysis in acid whey. 相似文献
43.
Effectiveness of 1-bromo-3-chloro-5,5-dimethylhydantoin against Legionella pneumophila in a cooling tower 总被引:2,自引:0,他引:2
Cooling towers are considered to be man-made amplifiers of Legionella spp. Thus, the proper maintenance and choice of biocides is important. The only biocidal measure that has thus far been shown to be effective in field tests is the judicious use of chlorination. Perturbation studies with 1-bromo-3-chloro-5, 5-dimethylhydantoin (Bromicide; Great Lakes Chemical Corp., West Lafayette, Ind.) (BCD) were conducted on an industrial cooling tower shown to contain Legionella pneumophila. At the concentrations recommended by the manufacturer, neither the density nor the activity of L. pneumophila was affected. At comcentrations greater than 2.0 ppm (2.0 micorgram/ml) free of residual, BCD was not effective in reducing L. pneumophila to source water concentrations, nor was it effective in reducing the 2-p-iodophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride activity of the bacterium in situ. The data indicate that at concentrations up to 2.0 ppm, BCD is not effective in these tower studies. 相似文献
44.
Methanogenic Activity and Structural Characteristics of the Microbial Biofilm On a Needle-Punched Polyester Support 总被引:2,自引:0,他引:2 下载免费PDF全文
Martin Harvey Cecil W. Forsberg Terry J. Beveridge Jack Pos John R. Ogilvie 《Applied microbiology》1984,48(3):633-638
In a downflow stationary fixed-film anaerobic reactor receiving a swine waste influent, few bacteria were observed to be tightly adherent to the surfaces of the needle-punched polyester support material. However, there was a morphologically complex, dense population of bacteria trapped within the matrix. Frequently large microcolonies of a uniform morphological type of bacteria were observed. These were particularly evident for methanosarcina-like bacteria which grew forming large aggregates of unseparated cells. Leafy deposits of electron-dense, calcium- and phosphorus-enriched material coated the polyester matrix and some cells. As the biofilm matured there was more extensive mineral deposition which completely entrapped cells. The entrapped cells appeared to autolyze, and many were partially degraded. Further impregnation of the matrix with minerals and apparent cell death may eventually have a deleterious effect on the methanogenic activity of the biofilm. 相似文献
45.
The extraordinary sensitivity of early erythroid progenitor cells (BFU-e) of normal human bone marrow to tritiated thymidine ([3H]TdR) was studied. While exposure of bone-marrow cells to [3H]TdR for 1 hr resulted in the death of only 40% of the granulocyte-macrophage progenitor cells (CFU-c), 90% of BFU-e were killed. Experiments in which normal bone-marrow cells were mixed with bone-marrow cells which had been exposed to [3H]TdR demonstrated that the excessive killing of BFU-e by [3H]TdR reflected carry-over of the [3H]TdR by the exposed cells. A carry-over effect was not observed for CFU-c, suggesting the presence of a fundamental difference in the metabolism of TdR between CFU-c and BFU-e. There was a suggestion of a carry-over effect regarding two other S-phase-specific agents, hydroxyurea and 1-β-D-arabinofuranosylcytosine. 相似文献
46.
Oren Zinder Philip G. Hoffman William M. Bonner Dr Harvey B. Pollard 《Cell and tissue research》1978,188(2):153-170
Summary A highly enriched fraction of plasma membranes from the bovine adrenal medulla has been isolated by differential and sucrose gradient centrifugation. The membranes were found to occur as 0.1–0.5 diameter vesicles and to equilibrate at a density of 1.13–1.14 g/ml. This fraction was characterized by 4-fold elevated levels of adenylate cyclase and 20-fold elevated levels of 5-nucleotidase. Secretory vesicle membranes, isolated by repeated hypotonie and hypertonic shocks of whole vesicles, were found to equilibrate between d = 1.08 and d = 1.12 on a sucrose density step gradient. These membranes were highly enriched in cytochrome b562 and dopamine--hydroxylase. Proteins in the two membranes were compared by SDS gel electrophoresis. All protein size classes found in the vesicle membrane fraction were also represented in the plasma membrane fraction, though in different proportions on the basis of staining intensity. The plasma membrane fraction contained prominent bands co-migrating with the - and -bands of tubulin, as well as a component co-migrating with actin. These bands were absent from the vesicle membranes. Fingerprint analysis of stained bands from the membrane fraction demonstrated that the components were indeed tubulin and actin. The plasma membranes contained twice as much sialic acid residues as did the chromaffin granule membranes, but had only half the cholesterol content on a weight basis. The cholesterolphospholipid ratio in the plasma membranes was 0.63, while in the secretory vesicle membranes it was 1.04. These results show that plasma membranes and secretory vesicle membranes are functionally and structurally different.Supported, in part, by a stipend to O.Z. from The Grant Foundation, New York 相似文献
47.
48.
Macrophages and neutrophils from human milk phagocytose and kill Staphylococcus aureus and Escherichia coli in vitro after opsonisation by the aqueous phase of milk as effectively as blood leucocytes in serum. They also phagocytose Candida albicans. The overgrowth of E coli resulting from the addition of iron to cultures of the organism in the aqueous phase of milk is not influenced by the presence of cells. We conclude that the phagocytosis and killing of bacteria by milk cells may contribute to the lower incidence of infection among breast-fed than artificially fed babies. 相似文献
49.
Babetta L. Marrone Jorge F. Rodriguez-Sierra Harvey H. Feder 《Hormones and behavior》1977,8(3):391-402
Progesterone has two types of inhibitory effects on female sexual behavior that have been well-documented in the guinea pig. The first occurs when high levels of progesterone are present around the start of the estrogen-priming process (“concurrent inhibition”). The second occurs immediately after the display of an estrogen-progesterone-induced period of estrous behavior (“sequential inhibition”). In the present set of experiments, we show that the rat, like the guinea pig, is capable of exhibiting both of these inhibitory effects of progesterone. However, rats require higher doses of progesterone than guinea pigs, at least for concurrent inhibition to be evident. In addition, we show that the dose of progesterone required in a single injection to produce concurrent inhibition is higher than the dose required to produce sequential inhibition in rats. A theory of how progesterone may be accomplishing its inhibitory effects on female sexual behavior in rodents is presented. 相似文献
50.
Frank J. Abramcheck James T. Blankemeyer William R. Harvey 《Journal of biological physics》1980,8(1):32-44
The size of the extracellular space in the isolated midgut ofManduca sexta measured statically with labeled sucrose and with labeled inulin was 48 and 50 percent of tissue water respectively. Both labeled sulfate and labeled mannitol yielded loading spaces which approached the volume of the tissue water with increasing pulse time and are not valid markers of the extracellular space. A washout method yielded unreliable values for the sucrose and inulin spaces and its use cannot be justified using presently available midgut chamber designs. Values of the sucrose space measured statistically in this study and other studies using different Lepidopteran larvae and different perfusion chambers range from 42 to 48 percent of the tissue water. Agreement between published values of the sulfate space and these values of the sucrose space is fortuitous, the labeling pulses being short enough to yield approximately half saturation of the actual sulfate loading space. 相似文献