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Glutathione replenishment capacity is lower in isolated perivenous than in periportal hepatocytes. 总被引:1,自引:1,他引:0 下载免费PDF全文
The zonal distribution of GSH metabolism was investigated by comparing hepatocytes obtained from the periportal (zone 1) or perivenous (zone 3) region by digitonin/collagenase perfusion. Freshly isolated periportal and perivenous cells had similar viability (dye exclusion, lactate dehydrogenase leakage and ATP content) and GSH content (2.4 and 2.7 mumol/g respectively). During incubation, periportal cells slowly accumulated GSH (0.35 mumol/h per g), whereas in perivenous cells a decrease occurred (-0.14 mumol/h per g). Also, in the presence of either L-methionine or L-cysteine (0.5 mM) periportal hepatocytes accumulated GSH much faster (3.5 mumol/h per g) than did perivenous cells (1.9 mumol/h per g). These periportal-perivenous differences were also found in cells from fasted rats. Efflux of GSH was faster from perivenous cells than from periportal cells, but this difference only explained 10-20% of the periportal-perivenous difference in accumulation. Furthermore, periportal cells accumulated GSH to a plateau 26-40% higher than in perivenous cells. There was no significant difference in gamma-glutamylcysteine synthetase or glutathione synthetase activity between the periportal and perivenous cell preparations. The periportal-perivenous difference in GSH accumulation was unaffected by inhibition of gamma-glutamyl transpeptidase or by 5 mM-glutamate or -glutamine, but was slightly diminished by 2 mM-L-methionine. This suggests differences between periportal and perivenous cells in their metabolism and/or transport of (sulphur) amino acids. Our results suggest that a lower GSH replenishment capacity of the hepatocytes from the perivenous region may contribute to the greater vulnerability of this region to xenobiotic damage. 相似文献
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R Parrilla K Okawa K O Lindros U J Zimmerman K Kobayashi J R Williamson 《The Journal of biological chemistry》1974,249(15):4926-4933
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The activities of beta-N-acetylglucosaminidase, beta-glucuronidase, alpha-L-iduronidase and acid phosphatase were all significantly higher in the cell lysates from the periportal than from the perivenous region obtained by the regioselective digitonin treatment of the perfused liver. The activities of cathepsins B, H and L were only slightly higher in the periportal than in the perivenous cell lysates. These results support the view that there is little zonation of lysosomal degradation of proteins, whereas the enzymatic capacity for degradation of glycosaminoglycans may be more active in the periportal region. 相似文献
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Using natural spawning and artificial fertilization, the entire process of development from eggs to juveniles was observed in the sea-star, Asterina batheri Goto.
The breeding season of this animal in Tsukumo Bay and Toyama Bay is estimated to be late summer. The spawned eggs are approximately 430 μm in diameter and float near the surface of sea water. They develop, through a wrinkled blastula stage by holoblastic. radial cleavage, into a pear-shaped brachiolaria bearing 3 blunt brachiolar arms. Metamorphosis takes place while the brachiolariae are swimming. Ten days after fertilization, metamorphosis is complete; the resulting juveniles are about 800 μm in diameter and colored pale brown with a green tint. They bear 2 pairs of tube-feet and a terminal tentacle in each arm.
Development of this species is thus of the direct type, and very similar in every respect to that of Asterina coronata japonica , which is closely related to the present species. 相似文献
The breeding season of this animal in Tsukumo Bay and Toyama Bay is estimated to be late summer. The spawned eggs are approximately 430 μm in diameter and float near the surface of sea water. They develop, through a wrinkled blastula stage by holoblastic. radial cleavage, into a pear-shaped brachiolaria bearing 3 blunt brachiolar arms. Metamorphosis takes place while the brachiolariae are swimming. Ten days after fertilization, metamorphosis is complete; the resulting juveniles are about 800 μm in diameter and colored pale brown with a green tint. They bear 2 pairs of tube-feet and a terminal tentacle in each arm.
Development of this species is thus of the direct type, and very similar in every respect to that of Asterina coronata japonica , which is closely related to the present species. 相似文献
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Mesophyll conductance decreases in the wild type but not in an ABA‐deficient mutant (aba1) of Nicotiana plumbaginifolia under drought conditions 下载免费PDF全文
YUSUKE MIZOKAMI KO NOGUCHI MIKIKO KOJIMA HITOSHI SAKAKIBARA ICHIRO TERASHIMA 《Plant, cell & environment》2015,38(3):388-398
Under drought conditions, leaf photosynthesis is limited by the supply of CO2. Drought induces production of abscisic acid (ABA), and ABA decreases stomatal conductance (gs). Previous papers reported that the drought stress also causes the decrease in mesophyll conductance (gm). However, the relationships between ABA content and gm are unclear. We investigated the responses of gm to the leaf ABA content [(ABA)L] using an ABA‐deficient mutant, aba1, and the wild type (WT) of Nicotiana plumbaginifolia. We also measured leaf water potential (ΨL) because leaf hydraulics may be related to gm. Under drought conditions, gm decreased with the increase in (ABA)L in WT, whereas both (ABA)L and gm were unchanged by the drought treatment in aba1. Exogenously applied ABA decreased gm in both WT and aba1 in a dose‐dependent manner. ΨL in WT was decreased by the drought treatment to ?0.7 MPa, whereas ΨL in aba1 was around ?0.8 MPa even under the well‐watered conditions and unchanged by the drought treatment. From these results, we conclude that the increase in (ABA)L is crucial for the decrease in gm under drought conditions. We discuss possible relationships between the decrease in gm and changes in the leaf hydraulics. 相似文献
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Kelly S Swanson Scot E Dowd Jan S Suchodolski Ingmar S Middelbos Brittany M Vester Kathleen A Barry Karen E Nelson Manolito Torralba Bernard Henrissat Pedro M Coutinho Isaac KO Cann Bryan A White George C Fahey Jr 《The ISME journal》2011,5(4):639-649
This study is the first to use a metagenomics approach to characterize the phylogeny and functional capacity of the canine gastrointestinal microbiome. Six healthy adult dogs were used in a crossover design and fed a low-fiber control diet (K9C) or one containing 7.5% beet pulp (K9BP). Pooled fecal DNA samples from each treatment were subjected to 454 pyrosequencing, generating 503 280 (K9C) and 505 061 (K9BP) sequences. Dominant bacterial phyla included the Bacteroidetes/Chlorobi group and Firmicutes, both of which comprised ∼35% of all sequences, followed by Proteobacteria (13–15%) and Fusobacteria (7–8%). K9C had a greater percentage of Bacteroidetes, Fusobacteria and Proteobacteria, whereas K9BP had greater proportions of the Bacteroidetes/Chlorobi group and Firmicutes. Archaea were not altered by diet and represented ∼1% of all sequences. All archaea were members of Crenarchaeota and Euryarchaeota, with methanogens being the most abundant and diverse. Three fungi phylotypes were present in K9C, but none in K9BP. Less than 0.4% of sequences were of viral origin, with >99% of them associated with bacteriophages. Primary functional categories were not significantly affected by diet and were associated with carbohydrates; protein metabolism; DNA metabolism; cofactors, vitamins, prosthetic groups and pigments; amino acids and derivatives; cell wall and capsule; and virulence. Hierarchical clustering of several gastrointestinal metagenomes demonstrated phylogenetic and metabolic similarity between dogs, humans and mice. More research is required to provide deeper coverage of the canine microbiome, evaluate effects of age, genetics or environment on its composition and activity, and identify its role in gastrointestinal disease. 相似文献