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101.
The in vitro occurrence of apoptosis in hepatic cells has not been well characterized because it depends on apoptosis inducing-agents
and culture conditions. Furthermore, for a given hepatic cell and the same agent, discrepant results have been reported depending
on the technique used to evaluate the proportion of apoptotic cells. In this study, we compared the effects of several apoptosis-inducing
agents – transforming growth factor β1 (TGF-β1), retinoic acid (RA), okadaic acid (OA), and cycloheximide (CY) – on two types of hepatic cells, the human hepatoma cell
line Hep3B and normal rat hepatocytes, maintained either plated for 24 to 48 h or in suspension for 20 h. Chromatin condensation
and/or nucleus fragmentation were investigated morphologically by DAPI staining. DNA fragmentation was investigated biochemically
by agarose gel electrophoresis and poly(ADP-ribose) polymerase (PARP) cleavage was studied by western blot. Apoptotic cells
were quantified either by counting cells on UV microscopy after DAPI staining or by flow cytometry. Nuclear changes, the ladder
pattern on DNA electrophoresis and PARP cleavage were observed in plated cells, hepatoma cells and normal rat hepatocytes,
with all inducers but especially with OA. Semiquantification confirmed that OA was a strong inducer in plated cells under
the present conditions, since about 14% and 30% of Hep3B cells (with DAPI staining and flow cytometry, respectively) were
apoptotic after 48 h treatment, while, with the other inducers, apoptosis was weaker and discrepancies were also observed
between the two counting methods (TGF-β1; 4% and 12%; RA, 7% and 12%; CY, 4% and 16%, with DAPI staining and flow cytometry, respectively). OA induced a moderate
apoptosis in cultured hepatocytes (13% with DAPI staining), while TGF-β1, RA and CY were found to be weakly apoptotic (respectively 4% for the first two and 6% for the last ) after 48 h. In contrast,
in suspension cells, apoptosis was observed neither in Hep3B cells nor in normal hepatocytes, whatever the apoptotic inducer
and whatever the techniques used to detect apoptosis. In conclusion, our results show that induction of apoptosis in hepatic
cells depends not only on the apoptosis-inducing agent but also on the culture conditions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
102.
H.J. Toutain V. Moronvalle-Halley J.P. Sarsat C. Chelin D. Hoet D. Leroy 《Cell biology and toxicology》1998,14(3):175-190
We examined the maintenance of functional and morphological integrity of precision-cut rat liver slices cultured in various incubation systems and conditions for 72 h. Slices were incubated (37°C) for 6, 24, 48, and 72 h in supplemented Williams E medium in 6-well plastic culture plates on a gyratory shaking platform (WPCS) or in a rotating organ culture system (ROCS) using 5% CO2–95% air (WPCS/air or ROCS/air) or 5% CO2–70% O2–25% N2 (WPCS/ O2 or ROCS/ O2). Biochemical and functional parameters of slices maintained in WPCS/air or WPCS/ O2 were almost totally inhibited after 24 h, in keeping with the extensive and diffuse coalescing coagulative necrosis typical of post-ischemic injury affecting almost all the slice surface after 48 h. As compared to freshly isolated slices, slices maintained in ROCS/air for 72 h showed stable ATP and GSH content, increased protein synthesis, and a slight steady decrease in GST activity, while ATP and GST activity remained stable and protein synthesis and GSH content increased in slices incubated in ROCS/ O2 for 72 h. The extent of coagulative necrosis was markedly lower in longitudinal sections from slices incubated for 72 h in ROCS/ O2 than in ROCS/air. Transversal sections from slices kept in ROCS/air for 72 h showed a thick central band of necrotic cells edged by two peripheral layers of viable hepatocytes, whereas most of the slice was composed of viable hepatocytes lined by two thin layers of necrotic cells after 72 h in ROCS/ O2. ROCS/ O2 emerged as the system best preserving the histological and functional integrity of rat liver slices in long-term culture. 相似文献
103.
Farm characteristics and the vegetative diversity of grasslands in the North of England: a policy perspective 总被引:1,自引:0,他引:1
A survey of 36 fields across 11 farms in the North of England was conducted to record the plant species diversity of grassland communities under various base conditions. Data pertaining to topographical advantage, farm management strategy and soil type were also collected for each field site. The relationship between management inputs and base environmental conditions and the resultant diversity of flora were identified through ordination techniques. The results show a total of 111 species being observed across the sample and some expected relationship emerge, but they also suggest that complementary management techniques can have opposing or conflicting effects on species prevalence. The study argues that provision or use of such information should be paramount within environmental policy formulation where site-specific management plans are used to produce environmental goods. 相似文献
104.
Abstract Natural enemies play an important role in inhibiting population growth of pine caterpillar, but they are difficult to be used in systematic management models. This paper attempts to use some forest stand factors to substitute the effect of natural enemies, which could be used in management models. Through the studies from more than 200 stand plots with different stand conditions in Qu County, Changshan County, and Longyou County of Zhejiang Province, 16 predominant species groups from insect community were selected, and the canonical correlation coefficient between the diversity index, species number, individual number of predominant species and the stand factors was analyzed. The results indicated that the canopy density and ground vegetation were the key stand factors for characterizing the function of insect community. The forest area was divided into four types according to the variation of canopy and vegetation conditions by using cluster analysis. The regression models between the rate of variation of pine caterpillar density and the forest factors including canopy density and vegetation covers were developed in each type of forests. There were significant differences in diversity index, species number, individual number of insect community and population density of pine caterpillar among four types of forests, and correlation coefficients of the four regression models were rather high ( r =0. 924 — 0. 964). This means that the classification of the forest stands is reasonable and the stand factors can characterize the effect of natural enemies in practice. 相似文献
105.
Jos Moreno M. Angeles Vargas Hctor Olivares Joaquín Rivas Miguel G. Guerrero 《Journal of biotechnology》1998,60(3):2139-182
The halotolerant, filamentous, heterocystous cyanobacterium Anabaena sp. ATCC 33047 released, during the stationary growth phase in batch culture and, at low dilution rate, in continuous culture, large amounts of an exopolysaccharide (EPS) to the culture medium. Different environmental, nutritional and physical parameters affected production and accumulation of the EPS. The presence of either a combined nitrogen source or NaCl at high concentration led to decreased EPS production, without affecting cell growth. In contrast, generation of the EPS was markedly enhanced in response to an increase in either air flow rate, temperature or irradiance. In continuous culture, accumulation of EPS in the medium increased in response to a decrease in the dilution rate, with maximal EPS productivity being reached at a dilution rate of 0.03 h−1. 相似文献
106.
The abiotic conditions required for eradication of Polymyxa betae, the vector of Beet necrotic yellow vein virus in sugar beet, were investigated. Survival of resting spores of P. betae was determined under aerobic (30 min, 4 days and 21 days) and anaerobic (4 days) conditions under several temperature regimes in a water suspension and in leachate extracted from an aerobic compost heap. In water under aerobic conditions the lethal temperature was 60, 55 and 40°C for exposure times of 30 min, 4 days and 21 days, respectively. The effect of compost leachate and/or anaerobic conditions on survival of P. betae depended on temperature. After incubation for 4 days at 20°C, no significant effects of anaerobic conditions or leachate on the survival of P. betae were found. However, at 40°C for 4 days under anaerobic conditions, survival of P. betae was significantly lower than survival under aerobic conditions in water as well as in leachate. In leachate taken from an aerobic compost heap, aerobically incubated at 40°C for 4 days, survival of P. betae was significantly lower than survival in water at the same temperature. As anaerobic spots are prevalent in aerobic compost heaps, especially during the thermophilic phase, actual inactivation temperatures under composting conditions are likely to be lower than the temperatures we found for eradication in water under aerobic conditions. 相似文献
107.
108.
Xinghui Lu Runguo Zang Yi Ding Susan G. Letcher Wenxing Long Yunfeng Huang 《Biotropica》2014,46(4):404-414
The seedling stage is generally the most important bottleneck for the successful regeneration of trees in forests. The traits of seedlings, particularly biomass allocation and root traits, are more easily quantified than the traits of adults. In this study, we tested the hypothesis that seedling traits vary and trade‐off tracking the changing environment during secondary succession. We measured the major morphological traits of 27 dominant species and the major environmental factors in a chronosequence (30‐yr‐old fallow, 60‐yr‐old fallow, and old growth forest) after shifting cultivation in a tropical lowland rain forest on Hainan Island, China. The 30‐yr‐old fallow had higher light and nutrient availability, and the older forests had higher soil water content. Redundancy analysis based on species abundance and environmental factors revealed groups of seedlings that dominate in different stages of succession. Seedlings in different stages of succession had different strategies of biomass allocation for harvesting resources that varied in availability. Species characteristic of younger forest had higher allocation to roots and higher specific leaf area, while species characteristic of older forest had higher allocation to leaves. Our study suggests that the variations and trade‐offs in the major functional traits of tree seedlings among successional classes may reflect changes in environmental conditions during succession. 相似文献
109.
We evaluated altitudinal segregation in two Sturnira species as a mechanism allowing their coexistence. Tests were devised to discern between interspecific interactions and regional responses to geographic and environmental variables, using extensive capture data from 18 montane rain forest sites. No significant correlation between captures was found. Additionally and according to the hypothesis of historical occupation of highland versus lowland forests, each species has shown specificity in their response to the geographical and environmental variables. Our results indicated that abundance patterns in these bats likely result from the regional distribution of each species rather than local interactions between them, a pattern that may have ancient roots within the group. 相似文献
110.