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281.
Mixed-species primate exhibits are becoming more common in zoological parks as a means to display a diverse array of animals both more naturalistically and with more economy of space. Here, we describe behavioral changes during the introduction process of a pair of pied tamarins (Saguinus bicolor) to an established group of black howler monkeys (Allouatta caraya) and white-faced saki monkeys (Pithecia pithecia). Data were collected during six phases, representing introductions among the various species and to exhibit space and off-exhibit holding. The pied tamarins were consistently the most active of the three species. Although activity levels of the howler and saki monkeys remained constant throughout, that of the tamarins declined as the introduction progressed. Several episodes of aggression between the tamarins and the sakis were observed, but did not coincide with patterns predicted by previous intra-specific introductions. The three-species mix remained stable for several months; however, escalating aggression ultimately led to the removal of the sakis from the mixed-species exhibit. Despite our mixed results, we contend that only through continued trials, coupled with careful and systematic monitoring, can we ultimately identify stable mixes of species.  相似文献   
282.
羊草草地生长季放牧山羊采食量和食性选择   总被引:13,自引:1,他引:12  
王旭  王德利  刘颖  巴雷  孙伟  张宝田 《生态学报》2002,22(5):661-667
在松嫩平原羊草草地,通过控制放牧实验对山羊的时限采食量和食性选择进行了研究。结果表明:(1)5-9月份,山羊的时限(1h)采食量平均为0.42kg干物质,其季节动态为5月份最低,随季节推移不断增大,8月份达到最大,9月份又有所减小;时限采食量基本上随放牧率减小而增大,但在最低放牧率小区有所减小。(2)山羊的食性选择随季节推移和放牧率不同而变化。(3)山羊对20-25cm高度草层的选择性最高;各高度草层的食性选择指数随季节推移和放牧率不同而变化;山羊对不同植物的高度选择性存在差异,但高度选择指数的最大值都在15-30cm范围内。  相似文献   
283.
Among examined microbial growth regulators of alkyl hydroxybenzene group (hexylresorcinol, methylresorcinol, and hydroxyethylphenol), only hexylresorcinol induces cellular SOS response, demonstrating a dose-dependent increase of the induction factor in the SOS chromotest with the Escherichia coli PQ37 strain. At the highest of used concentrations (100 micrograms/ml), hydroxyethylphenol and nonalkylated resorcinol were shown to exert a weak toxic effect, reducing the activity of constitutive alkaline phosphatase, but did not induce SOS response. Nontoxic methylresorcinol did not induce genome damage, which can trigger SOS functions. It is concluded that substitutions in phenolic ring affect genotoxic activity of alkylresorcinols.  相似文献   
284.
Here we report on the study of the effects of different antineoplastic agents, including cytarabine, 4-hydroperoxyifosfamide, the activated form of ifosfamide, vincristine, and paclitaxel, with regard to their capacity to modulate the amount of cytoplasmic and membrane-bound heat shock protein 70 (Hsp70). Hsp70 levels were measured in the myelogenous leukemic cell line K562, in the human colon carcinoma cell line CX2, and in peripheral blood lymphocytes (PBL) under physiological conditions (37 degrees C), and following non-lethal heat shock at 41.8 degrees C. A concentration of 1 microM and an incubation period of 2 h were determined as non-lethal, since none of the different antineoplastic agents induced necrosis or apoptosis in untreated or heat-shocked cells under these conditions. Our results show that tubulin-interacting agents, including vincristine and paclitaxel, but not DNA-interacting agents, including cytarabine and ifosfamide, selectively increase the amount of cytoplasmic Hsp70 in tumor and normal cells, as measured by semi-quantitative Western blot analysis. Mechanistically, a vincristine- and paclitaxel-induced tubulin assembly, as demonstrated by immunofluorescence microscopy, might be responsible for the elevated cytoplasmic Hsp70 levels. Interestingly, an increased membrane expression of Hsp70 following treatment with vincristine or paclitaxel was selectively observed on tumor cells, but not on normal cells.  相似文献   
285.
Among examined microbial growth regulators of alkyl hydroxybenzene group (hexylresorcinol, methylresorcinol, and hydroxyethylphenol), only hexylresorcinol induces cellular SOS response, demonstrating a dose-dependent increase of the induction factor in the SOS chromotest with the Escherichia coli PQ37 strain. At the highest of used concentrations (100 g/ml), hydroxyethylphenol and nonalkylated resorcinol were shown to exert a weak toxic effect, reducing the activity of constitutive alkaline phosphatase, but did not induce SOS response. Nontoxic methylresorcinol did not induce genome damage, which can trigger SOS functions. It is concluded that substitutions in phenolic ring affect genotoxic activity of alkylresorcinols.  相似文献   
286.
The presence of anti-α-fodrin autoantibodies has been reported to be a highly specific and sensitive test for the diagnosis of Sjögren's syndrome (SjS). We looked (in Nijmegen) for anti-α-fodrin, anti-Ro60, and anti-La autoantibodies in a cohort of 51 patients with rheumatic diseases (primary SjS [21], secondary SjS [6], rheumatoid arthritis [RA] [12], systemic lupus erythematosus [SLE] [6], and scleroderma [6]) and in 28 healthy subjects, using ELISA, immunoblotting, and immunoprecipitation. The same samples were analyzed with an alternative anti-α-fodrin ELISA in Hanover. The Nijmegen ELISA of the sera from primary SjS showed sensitivities of 43% and 48% for IgA- and IgG-type anti-α-fodrin antibodies, respectively. The Hanover ELISA showed sensitivities of 38% and 10% for IgA- and IgG-type anti-α-fodrin antibodies, respectively. The ELISAs for α-fodrin showed six (Nijmegen) and four (Hanover) anti-α-fodrin-positive RA sera. IgA and IgG anti-fodrin antibodies were also present in four patients with secondary SjS. The sensitivities of Ro60 and La-antibodies in the Nijmegen ELISA were 67% and 62%, respectively. Unlike anti-α-fodrin antibodies, all anti-Ro60 and anti-La positive sera could be confirmed by immunoblotting or RNA immunoprecipitation. Thus, anti-Ro and anti-La autoantibodies were more sensitive than anti-α-fodrin autoantibodies in ELISA and were more frequently confirmed by other techniques. Anti-La antibodies appear to be more disease-specific than anti-α-fodrin antibodies, which are also found in RA sera. Therefore, the measurement of anti-α-fodrin autoantibodies does not add much to the diagnosis of Sjögren's syndrome.  相似文献   
287.
The authors present their experience with the design of expanded skin flaps gained over the past two decades in a large series of 995 expanded flap reconstructions performed in 626 operations in 430 patients. The indications for tissue expansion were giant congenital pigmented nevi (72.7 percent), scar contractures (11.2 percent), and a remainder for a variety of congenital and acquired deformities. Surgical strategies were reviewed retrospectively to determine the location in the body where the tissue expansion was performed, the number of procedures required to accomplish the reconstructive goal, and the design of the expanded flap that was used to reconstruct the involved area. Specific points that were noticed included contour deformities (such as webbing, dog-ears, or decreased limb circumference) following flap reconstruction, anatomic distortions (such as distortion of the eyebrow or the distance from the brow to hairline) following reconstruction, final position of the scars in relation to anatomic landmarks, borders of aesthetic units, and relaxed skin tension lines, and the potential for later scar contracture. Careful examination of reconstruction by region of involvement demonstrated significant advantages in the use of expanded transposition flaps over pure advancement. These advantages and the modifications in the design of expanded flaps for each body region are discussed in a series of representative cases. They emphasize the ability of transposition flaps to dissipate tension away from the flap apex and distribute it more proximally, thus redirecting the tension lines so there is less likelihood of anatomic distortion in the reconstructed area. Also, flaps designed in this manner allow improved contour by avoiding webbing, tenting across concavities, and bunching of skin laterally. The authors conclude that restricting the expanded flap design to advancement alone to minimize potential scarring severely limits the reconstructive capabilities of the added tissue and distracts from the surgeon's ability to accomplish the initial reconstructive goal. The cost of additional incisions is worthwhile to achieve better final contour of the reconstructed part, lesser risk of anatomic distortion, better position of the scars, and lowered risk of scar contracture.  相似文献   
288.

Background  

Accumulating evidences suggest that Hsp 70, the inducible component of Hsp70 family, might release from a living cell. Here we show that a pharmacological inhibitor of phospholipase C activity U73122 caused a 2–4 fold reduction of an intracellular level of Hsp70 in A431 human carcinoma cells.  相似文献   
289.
The response of cancer cells to apoptosis-inducing agents can be characterized by 2 opposing factors, the proapoptotic caspase cascade and the antiapoptotic stress protein Hsp70. We show here that these factors interact in U-937 leukemia cells induced to apoptosis with anticancer drugs, etoposide and adriamycin (ADR). The protective effect of Hsp70 was verified using 2 approaches: mild heat stress and transfection-mediated overexpression of the Hsp70 gene. The increase in Hsp70 levels attained by these 2 methods was found to postpone caspase activation for 12-18 hours. An in vitro assay was developed using mouse myeloma NS0/1 cells, which lack the expression of Hsp70. Measurement of DEVD-ase activity in extracts of apoptotic NS0/1 cells incubated with purified Hsp70 showed that Hsp70 reduced caspase activity by up to 50% of its control value in a dose-dependent manner. The hypothesis that the inhibitory effect of Hsp70 on caspase-3/7 activity related to a direct interaction between Hsp70 and the caspases was tested by reciprocal immunoprecipitations and Far-western analyses. These tests were performed with extracts of Hsp70-overexpressing, control, and ADR-treated U-937 cells and using anti-caspase-3, caspase-7, and anti-Hsp70 antibodies, and the data clearly showed that Hsp70 was able to interact with the proforms of these caspases in cell lysates and with reconstituted purified proteins but did not bind the activated forms of either caspase-3 or -7. This association was also corroborated by a novel, enzyme-linked immunosorbent assay-like assay, protein interaction assay, that combined the advantages of immunoprecipitation and immunoblotting in a 96-well microplate-based assay. Thus, Hsp70 may act to suppress caspase-dependent apoptotic signaling through binding the precursor forms of both caspase-3 and caspase-7 and preventing their maturation.  相似文献   
290.
The expression of a major stress protein Hsp70 may be induced by a great number of cytotoxic agents and also by factors known to cause process of cell proliferation or apoptosis. After induction the synthesis of Hsp70 is reduced to its basic level within first 2-6 hours after inducer application, while the high content of the protein may persist up to several days. The aim of this study was to understand the reason of such a long storage of Hsp70 in U-937 cells induced with three distinct factors. The data of immunoblotting showed that the mild heat shock at 43 degrees C for 60 min, phorbol ester and tumor necrosis factor (the two latter known to induce differentiation and apoptosis, respectively) caused Hsp70 accumulation, the protein level being high within 48 hours and then slowly declined to the basal level. According to the results of chromatography on anti-Hsp70 antibody-Sepharose gel, approximately 50% of the protein was retarded by the gel, while the other part was not recognized by immunoglobulins. Among proteins bound to the Hsp70, three polypeptides were identified as actin, p65 and c-Rel, two latter being constituents of NF-kappa B regulatory complex. The data demonstrate that besides its traditional target, i.e. newly synthesized or abnormal polypeptides, Hsp70 is able to bind mature, active proteins.  相似文献   
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