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11.
Summary We have identified and localized two incompatibility determinants (IncA and IncB) within a 1.3 kb segment of ColE2 sufficient for autonomous replication. The IncA determinant is localized in a region shorter than 250 bp and expresses incompatibility against both ColE2 and ColE3. The region which determines sensitivity to the IncA determinant seems to overlap with the region specifying the IncA determinant. The expression of the trans-acting factor(s) specifically required for replication of ColE2 interferes with expression of the IncA determinant against ColE2 but not against ColE3. The IncA determinant might be at least partly responsible for the copy number control of the plasmid. The IncB determinant is localized in a 50 bp region (origin) which is sufficient for initiation of replication in the presence of the trans-acting factor(s). The IncB determinant is specific for ColE2 and seems to be due to titration of the trans-acting essential replication factor(s) by binding. 相似文献
12.
Toshihiro Mitaka Gerald L. Sattler Henry C. Pitot Yohichi Mochizuki 《Virchows Archiv. B, Cell pathology including molecular pathology》1992,62(1):329-335
Phenotypes of the cells developing into small colonies after days of primary culture of adult rat hepatocytes in serum-free
modified Dulbecco Modified Eagles’ medium containing 10 mM nicotinamide and 10 ng/ml epidermal growth factor were analyzed
immunocytochemically, cytochemically and ultrastructurally. Albumin, cytokeratin 8 and 18 were seen by immunocytochemical
techniques in the cells of the small colonies at Day 6. Transferrin, α-antitrypsin, ceruloplasmin, and haptoglobin, proteins
secreted by mature hepatocytes, were faintly stained in these cells as was α-fetoprotein. These proteins were secreted into
the culture medium as evidenced by immunoblot analysis. γ-Glutamyltransferase, alkaline phosphatase and glucose 6-phosphatase
were not present in the cells of the small colonies as well as the surrounding hepatocytes at Day 6 of culture. In addition,
ultrastructural examinations of the cells in the small colonies indicated that these cells not only had many characteristic
mitochondria and desmosomes, but also a few small peroxisomes. Such cells, even after 20 days in culture were proliferating,
as evidenced by the intranuclear presence of the proliferating cell nuclear antigen. The potential relation of these cells
to hepatocytes which may serve as the principal reserve for replicating hepatocytes is discussed. 相似文献
13.
N Yuasa T Taniguchi M Goda M Shibatani T Imada H Hihara 《National Institute of Animal Health quarterly》1983,23(3):75-77
An attempt was made to isolate chicken anemia agent (CAA) from chickens suffering from anemia in the field by using MDCC - MSB1 , which was an established cell line derived from Marek's disease lymphoma. When 99 chickens of 15 flocks were examined, CAA was isolated from 58 chickens of 12 flocks. The rate of CAA isolation with MDCC - MSB1 cells was almost the same as that determined by an in vivo method by chick inoculation. It was shown that CAA was more closely concerned with anemic diseases of chickens in the field than fowl adenoviruses. 相似文献
14.
At the developmental stage at which the apical hook passed the 3rd and 4th nodes, dark-grown seedlings of pea ( Pisum sativum L. cv. Progress No.9) opened the hook upright and then formed a new hook above the node nearly in the opposite direction to the previous one. In cv. Alaska, in contrast, many (about 84%) seedlings closed the hook in the original direction after they partially (up to about 110°) opened it at the 3rd node, thus doing a wagging movement, while a small percentage (about 16%) of the seedlings reversed the hook direction. Exposure to red light of cv. Alaska seedlings for 10 min increased the percentage of the hook reversion up to 71% or more. The hook reversion was never observed except when the hook part passed the nodes, suggesting the involvement of the nodes in the phenomenon. 相似文献
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We have analyzed the distribution of putative cholinergic neurons in whole-mount preparations of adult Drosophila melanogaster. Putative cholinergic neurons were visualized by X-gal staining of P-element transformed flies carrying a fusion gene consisting of 5′ flanking DNA from the choline acetyltransferase (ChAT) gene and a lacZ reporter gene. We have previously demonstrated that cryostat sections of transgenic flies carrying 7.4 kb of ChAT 5′ flanking DNA show reporter gene expression in a pattern essentially similar to the known distribution of ChAT protein. Whole-mount staining of these same flies by X-gal should thus represent the overall distribution of ChAT-positive neurons. Extensive staining was observed in the cephalic, thoracic, and stomodeal ganglia, primary sensory neurons in antenna, maxillary palps, labial palps, leg, wing, and male genitalia. Primary sensory neurons associated with photoreceptors and tactile receptors were not stained. We also examined the effects of partial deletions of the 7.4 kb fragment on reporter gene expression. Deletion of the 7.4 kb fragment to 1.2 kb resulted in a dramatic reduction of X-gal staining in the peripheral nervous system (PNS). This indicates that important regulatory elements for ChAT expression in the PNS exist in the distal region of the 7.4 kb fragment. The distal parts of the 7.4 kb fragment, when fused to a basal heterologous promoter, can independently confer gene expression in subsets of putative cholinergic neurons. With these constructs, however, strong ectopic expression was also observed in several non-neuronal tissues. © 1995 John Wiley & Sons, Inc. 相似文献
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19.
The effects of chemicals such as metal ions and typical organic enzyme inhibitors on the activity of deglycosylated β-fructofuranosidases ( P -1 and P -2) from Aureobasidium were observed and compared with those of native enzymes. P -1 and P -2 enzymes became sensitive to metal ions, such as Fe2+ , Co2+ , Ni2+ and Al3+ , after deglycosylation. The enzymes were also inhibited by a sulphydryl reagent (monoiodoacetic acid), a peptide-hydrolysing reagent (hydroxylamine) and chelating reagents (sodium citrate, EDTA and sodium azide) after deglycosylation. The importance of deglycosylation for the determination of the true characteristics of the enzymes against chemicals is discussed. 相似文献
20.
Efficiency of serum copper/zinc ratio for differential diagnosis of patients with and without lung cancer 总被引:1,自引:0,他引:1
Tsunehiro Oyama Koji Matsuno Toshihiro Kawamoto Tetsuya Mitsudomi Takayuki Shirakusa Yasushi Kodama 《Biological trace element research》1994,42(2):115-127
We examined serum copper (Cu), serum zinc (Zn), and the serum copper/zinc ratio (Cu/Zn) in 162 patients. All of them were
seen to have an abnormal shadow in the chest X-ray films, that is, 109 patients with lung cancer (LC) and 53 patients with
no lung cancer (NLC). The mean Cu and Cu/Zn in LC patients were significantly higher than those in NLC patients (p<0.05). In LC patients, Cu and Cu/Zn were higher and Zn was lower in advanced tumors than early ones. There was a significantly
clear relation between Cu or Cu/Zn and the tumor (T) stages. When the relative risk (RR) of LC was estimated, it was seen
that the higher Cu and Cu/Zn became, the higher RR became. Furthermore, we showed the sensitivity of the receiver operator
characteristic of the test (ROC) curve for Cu, Cu/Zn, and carcinoembryonic antigen (CEA) to diagnose LC, as explained in a
paragraph of methods.The determinations of Cu, Zn, and Cu/Zn are simple and inexpensive. They also appear to have a great diagnostic value in determining the local invasion of LC and as a screening test in the
high-risk patients for LC. 相似文献