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961.
初论蜘蛛目的种内变异类型 总被引:1,自引:1,他引:0
研究蜘蛛目中的种内变异,初步探讨蜘蛛的外生殖器结构的变异类型,并提出在蜘蛛分类学中树立种群分类概念的重要性。 相似文献
962.
Xenopus oocytes can synthesise but do not secrete the Z variant of human alpha 1-antitrypsin 总被引:7,自引:0,他引:7
Human liver mRNA was prepared from a patient homozygous for alpha 1-antitrypsin deficiency (PiZZ) and from a normal subject (PiMM). Both liver RNAs were microinjected into Xenopus oocytes and alpha 1-antitrypsin identified by immunoprecipitation. The normal M variant of alpha 1-antitrypsin is synthesised and secreted by Xenopus oocytes, the abnormal Z protein is not secreted and an intracellular form accumulates in the oocytes. In the presence of tunicamycin an unglycosylated form of M alpha 1-antitrypsin appears in the incubation medium but no corresponding unglycosylated version of the Z protein is secreted. 相似文献
963.
Chloe Rees-Spear Luke Muir Sarah A. Griffith Judith Heaney Yoann Aldon Jonne L. Snitselaar Peter Thomas Carl Graham Jeffrey Seow Nayung Lee Annachiara Rosa Chloe Roustan Catherine F. Houlihan Rogier W. Sanders Ravindra K. Gupta Peter Cherepanov Hans J. Stauss Eleni Nastouli Laura E. McCoy 《Cell reports》2021,34(12):108890
965.
966.
The biological control of posttranslational maturation and compartmentalization reactions that operate upon proteins during transport to their final cellular destinations is crucial for normal cellular function. Using the expression of mouse mammary tumor virus (MMTV) glycoproteins as sensitive probes in the viral-infected rat hepatoma cell line M1.54, we have discovered and documented a novel glucocorticoid-regulated trafficking pathway that controls the cell surface localization of MMTV glycoproteins. One complement-selected derivative of M1.54 cells, CR4, failed to compartmentalize cell surface MMTV glycoproteins in the presence of dexamethasone. To test genetically if this glycoprotein trafficking pathway is mediated by cellular or viral gene products, CR4 cells were fused with uninfected Fu5 rat hepatoma cells. Indirect immunofluorescence of CR4 X Fu5 heterokaryons revealed that Fu5 complemented the defect in CR4 only after exposure to 1 microM dexamethasone. The glucocorticoid inhibition of Fu5 proliferation was exploited to recover the receptor-deficient uninfected derivative EDR3 that expressed a 100-fold lower level of [3H]dexamethasone binding activity. Analysis of CR4 X EDR3 cell fusions by indirect immunofluorescence revealed that EDR4 cells complemented CR4 in a dexamethasone-dependent manner, suggesting that EDR3 supplied a functinal trafficking component while CR4 provided a functional glucocorticoid receptor to the heterokaryons. Taken together, our results demonstrate that cellular-encoded glucocorticoid-inducible components mediate the regulated trafficking of cell surface MMTV glycoproteins. 相似文献
967.
Anders Johannisson Birgitta Eriksson Herman Amnéus Gösta Zetterberg 《Cell biology and toxicology》1992,8(4):233-253
Attempts have been made to use the hypoxanthine-guanine-phospho-ribosyl-transferase-assay as a method for automated screening of agent-induced phenotypic variants of human peripheral lymphocytes reflecting 6-thioguanine resistance and assumed to indicate genotoxic action. Different protocols of the hypoxanthine-guanine-phospho-ribosyl-transferase-system were used in this study in order to investigate whether the system can be a candidate for a short-term test for a rapid and reliable identification of biological systems exposed to agents. The current protocols were based on: 1) fluoresceinated monoclonal antibodies against bromodeoxyuridine-DNA for labelling of 6-thioguanine-resistant human lymphocytes and direct flow-cytometric enumeration of bromodeoxyuridine-positive events and: 2) indirect flow-cytometric enrichment of 6-thioguanine-resistant cells labelled with 3H-thymidine followed by autoradiographic enumeration of positive events. Both the direct and the indirect enumeration method yielded similar results down to the range 10–4 with respect to frequency of variants. For the less time-consuming direct enumeration method the resolution was limited due to non-specific binding of the antibody and false positives. It was, nevertheless, sufficient to score variants induced in vitro with the mutagens EMS, MMC and TT in the same range as e.g. that of cancer patients during and after chemotherapy or radiotherapy, or that of psoriasis patients during and after PUVA (8-methoxypsoralen and long range UV light)-therapy. We conclude that the direct enumeration protocol can be used for a rapid screening of so called outliers, but a more sensitive test, such as the more time-consuming enrichment protocol based on autoradiography, must be used in order to score variants in the range 10–5–10–6
Abbreviations
3H-TdR
Tritiated thymidine
- BrdU
5-2-bromodeoxyuridine
- DNA
Deoxyribonucleic acid
- EMS
Ethyl-methanesulphonate
- FBS
Fetal bovine serum
- FITC
Fluorescein Isothiocyanate
- G0
Cell cycle stage
- G1
Cell cycle stage
- G2
Cell cycle stage
- HPRT
Hypoxanthine Guanine Phospho Ribosyl Transferase
- LI
Labelling index
- MMC
Mitomycin C
- PBL
Peripheral blood lymphocytes
- PBS
Phosphate buffered saline
- PHA
Phytohemagglutinin
- PI
Propidium iodide
- PUVA
8-Methoxypsoralen and long range UV-light therapy
- RNA
Ribonucleic acid
- RPMI
RPMI-1640 culturing medium
- Se
Early S-stage in the cell-cycle
- Sl
Late S-stage in the cell-cycle
- SCE
Sister chromatid exchange
- TG
6-Thioguanine
- TT
Thiotepa
- UV
Ultraviolet light
- Vf
Variant frequency 相似文献
968.
A comparison is made of single components of the homozygous variants A and D2 of bovine serum transferrin by tryptic, chymotryptic and cyanogen bromide digestion. It is concluded that there are three substitutions A:D2 - Glu:Asp, Lys: Arg and Asp:Gly. In the light of the recent work of Brocket al. (1980) it is concluded that all three substitutions occur in the C-terminal sequence of the chain. By homology with the sequence of human serum transferrin (MacGillivray et al., 1982) the Lys:Arg and Asp:Gly substitutions probably occur at residues 527 and 446, respectively, from the N -terminus. The Asp:Gly substitution is considered more likely than our earlier conclusion (Maeda, McKenzie & Shaw, 1977) that there is a deletion in the chain of D2 (A:D2 , Asp: —). The location of the Glu:Asp substitution is not known. 相似文献
969.
JEAN‐FRANOIS FLOT 《Molecular ecology resources》2007,7(6):974-977
champuru is an interactive, user‐friendly web software that facilitates the deconvolution of mixed chromatograms obtained when sequencing directly mixtures of two DNA templates of unequal lengths. The program takes as input two strings of characters describing the forward and reverse chromatograms as obtained by direct sequencing and returns, most often after several iterations aimed at correcting basecalling errors, the sequences of the two templates present in the mixture. champuru was written in perl , with a web interface accessible online at http://134.157.186.185/champuru/champuru.htm . 相似文献
970.
Efthimios E. Prinarakis Eva Tzelepi Maria Gazouli reas F. Mentis Leonidas S. Tzouvelekis 《FEMS microbiology letters》1996,139(2-3):229-234
Abstract An SHV type β-lactamase frequently found in enterobacteria isolated in Greek hospitals was analyzed. The enzyme (SHV-5a) conferred resistance to ceftazidime and aztreonam. The DNA sequence of the structural gene was determined. The deduced amino acid sequence showed that positions 70–73 were occupied by the active site tetrad Ser-Thr-Phe-Lys. As in SHV-5, Ser-238 and Lys-240 were present. However, one deletion (Gly-54) and three substitutions (Arg-140 for Ala, Asn-192 for Lys and Val-193 for Leu) differentiate SHV-5a β-lactamase from SHV-5. Asn-192 and Val-193 have been reported to date only in the R974 plasmid-mediated SHV-1 β-lactamase. Hydrolysis studies with SHV-5a and SHV-5 showed that the enzymes behaved similarly. Additional evidence that they were functionally indistinguishable was provided by the similar MICs of β-lactams when the enzymes were expressed under isogenic conditions. The sequence differences, however, indicate that they are derived from different ancestors. 相似文献