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41.
Hongzhang Zhou 《Insect Science》1996,3(4):329-337
Abstract The seasonality of the field population of Lagria hirta L. is remarkable: adults occur only from the end of June to the beginning of August, whereas larvae exist in the whole year except June. Based on the data of field observations and larval head-width measuring, the author demonstrated that L. hirta would reproduce in a very short interval in June to August; eggs hatch and develop (molt) into the 3rd, 4th or 5th (sometimes 6th) instar before winter; after larval overwintering, the beetles complete the larval development after total 8–10 times of molts and pupate in June. The larval development rate is decreased but not completely stopped during winter (the nonparametric median test, P<0. 01). This result changes the hitherto opinion of 4 or 5-instar larval development of L. hirta and will stimulate the studies on its life history. 相似文献
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Identification of a 175 kDa protein as the ligand-binding subunit of the rat liver sinusoidal endothelial cell hyaluronan receptor 总被引:2,自引:1,他引:1
The rat liver sinusoidal endothelial cell (LEC) hyaluronan (HA)receptor was previously identified using a photoaffinity HAderivative (J. BioL Chem., 267, 2045120456, 1992). Twopolypeptides with Mr = 175,000 and 166,000, were consistentlycrosslinked, suggesting that the LEC HA receptor is an oligomer.Whether one or both subunits participate in HA binding, wasnot determined. Here we investigate the HA-subunit interactionsand the potential oligomeric nature of the LEC HA receptor.When Sephacryl-400 gel filtration chromatography was used toenrich the HA receptor, the 175 kDa polypeptide was the majorband seen by SDS-PAGE analysis. Little staining was seen at166 kDa, suggesting that the 175 kDa protein could be separatedfrom the 166 kDa protein and still retain HA-binding activity.A ligand blot assay was used to determine if each individualsubunit could bind HA. LEC proteins were separated by nonreducingSDS-PAGE, and then immobilized onto nitrocellulose. 125I-HAbound to a 175 kDa polypeptide but not to the 166 kDa protein.A high molecular weight band of 相似文献
44.
Mary C. O'Sullivan Qibing Zhou Zhili Li Timothy B. Durham Donna Rattendi Schennella Lane Cyrus J. Bacchi 《Bioorganic & medicinal chemistry》1997,5(12):2145-2155
Trypanothione reductase (TR) occurs exclusively in trypanosomes and leishmania, which are the etiological agents of many diseases. TR plays a vital role in the antioxidant defenses of these parasites and inhibitors of TR have potential as antitrypanosomal agents. We describe the syntheses of several spermine and spermidine derivatives and the inhibiting effects of these compounds on T. cruzi TR. All of the inhibiting compounds displayed competitive inhibition of TR-mediated reduction of trypanothione disulfide. The three most effective compounds studied were N4,N8-bis(3-phenylpropyl)spermine (12), N4,N8-bis(2-naphthylmethyl)spermine (14), and N1,N8-bis(2-naphthylmethyl)spermidine (21), with Ki values of 3.5, 5.5 and 9.5 μM, respectively. Compounds 12, 14, and 21 were found to be potent trypanocides in vitro with IC50 values ranging from 0.19 to 0.83 μM against four T. brucei ssp. strains. However, these compounds did not prolong the lives of mice infected with trypanosomes. This work indicates that certain polyamine derivatives which target a unique pathway in Trypanosomatidae have potential as antitrypanosomal agents. 相似文献
45.
Physiologic and yield effects of mixtalol at various concentrations sprayed on rape at the anthesis stage were examined. Foliar sprays of 4 and 2 ppm mixtalol significantly increased the chlorophyll content of rape leaves and pods, reduced the accumulation of malondialdehyde and ethylene production, and delayed the degradation of superoxide dismutase and catalase activities of the rape plant. Mixtalol also increased root oxidizability. Meanwhile, the number of branches and pods per plant was increased, and a 10.7% and 8.2% increase of seed yield over the controls was observed with treatments of 4 and 2 ppm mixtalol, respectively. No significant effects from mixtalol were observed on the maturation of plants or on the seed oil content or the erucic acid and glucosinolate content. Total rape oil production increased with 4 and 2 ppm mixtalol significantly by 12.4% and 10.5%, respectively, over the controls.Abbreviations MTL
mixtalol
- MDA
malondialdehyde
- TBA
thiobarbituric acid
- SOD
Superoxide dismutase
- CAT
catalase
- TTC
tetrazolium 相似文献
46.
47.
The dissociation constants for the binding of ferric enterobactin with FepA and FecA are quantitated with displacement experiments. It is found that K
d for FepA is 12 times lower than the one for FecA. This indicates that FepA is an high-affinity receptor while FecA binds ferric enterobactin with a lower affinity. Monoclonal antibodies specific for binding epitopes of FepA inhibit the binding of ferric enterobactin with purified FepA. These same antibodies do not inhibit the binding of ferric enterobactin with purified FecA. This indicates that the binding epitopes in FecA and FepA are different. 相似文献
48.
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R W Leu A Q Zhou M J Kennedy B J Shannon 《Journal of immunology (Baltimore, Md. : 1950)》1991,146(4):1233-1239
Studies originally designed to assess the putative role of endogenous C5 in macrophage activation for antibody-dependent cellular cytotoxicity (ADCC) yielded unanticipated results. Resident and inflammatory peritoneal macrophages from C5-deficient AKR mice were found to have significantly lower capacity for FcR-dependent ADCC activation and phagocytosis of IgG-opsonized SRBC targets than did C5-competent C3HeB/FeJ (C3H) mice. Reconstitution of the ADCC response of AKR macrophages was accomplished initially with C5-sufficient C3H mouse serum, which suggested that endogenous C5 may be required for ADCC activation. However, further investigation largely eliminated C5 involvement in that a heat-labile component of C5-deficient AKR serum was shown to be active in the reconstitution of ADCC activation of AKR macrophages. Macrophages from AKR mice were found to have significantly lower levels of C1q mRNA synthesis, endogenous C1q levels, and C1q secretion than did C3H mouse macrophages as determined by Northern blot, Western blot, and presynthetic radiolabeling analysis, respectively. The addition of purified exogenous C1q to IgG-opsonized SRBC targets fully reconstituted ADCC activation for AKR inflammatory peritoneal macrophages to levels of normally FcR-responsive C3H macrophages. Similarly, exogenous C1q augmented FcR-dependent phagocytosis of AKR macrophages but had no effect on macrophages from responsive C3H mice. Our results indicate that AKR mice have a deficiency for FcR-dependent cellular cytotoxicity and phagocytosis that is related to their low potential for C1q synthesis and secretion rather than to their established genetic deficiency for C5 synthesis. We tentatively conclude that endogenous C1q is required as an accessory molecule for macrophage FcR-dependent effector functions and that C5 is not a prerequisite for ADCC activation. 相似文献