Effects of SARA on Oxygen–Glucose Deprivation in PC12 Cell Line

Ischemic stroke is a major composition of cerebrovascular disease, seriously threatening to human health in the world. Activin A (ActA), belonging to transforming growth factor-beta (TGF-β) super family, plays an important role in the hypoxic-ischemic brain injury through ActA/Smads pathway. While as an essential phosphorylation assistor in TGF-β signaling, the functions and mechanisms of smad anchor for receptor activation (SARA) in ischemic brain injury remain poorly understood. To solve this problem and explore the pathological processes of ischemic stroke, we used an Oxygen–Glucose deprivation (OGD) model in nerve growth factor-induced differentiated rattus PC12 pheochromocytoma cells and down regulated the expressions of SARA by RNA interference technology. Our results showed that the repression of SARA before OGD exposure reduced the expressions of Smad2, 3, 4 mRNA and the phosphorylation rate of Smad2 protein, but it did not affect the mRNA expressions of Smad7. After OGD treatment, ActA/Smads pathway was activated and the expression of SARA in the SARA pre-repression group was significantly up-regulated. The pre-repression of SARA increased the sensitivities of nerve-like cells to OGD damage. Moreover, the mRNA expression of Smad7 which was supposed to participate in the negative feedback of ActA/Smads pathway was also elevated due to OGD injury. Taken together, these results suggest a positive role of SARA in assisting the phosphorylation of Smad2 and maintaining the neuron protective effect of ActA/Smads pathway.     

New class I and II HLA alleles strongly associated with opposite patterns of progression to AIDS.

The genetics of resistance to infection by HIV-1 cohort consists of 200 slow and 75 rapid progressors to AIDS corresponding to the extremes of HIV disease outcome of 20,000 Caucasians of European descent. A comprehensive analysis of HLA class I and class II genes in this highly informative cohort has identified HLA alleles associated with fast or slow progression, including several not described previously. A quantitative analysis shows an overall HLA influence independent of and equal in magnitude (for the protective effect) to the effect of the CCR5-Delta32 mutation. Among HLA class I genes, A29 (p = 0.001) and B22 (p < 0.0001) are significantly associated with rapid progression, whereas B14 (p = 0.001) and C8 (p = 0.004) are significantly associated with nonprogression. The class I alleles B27, B57, C14 (protective), and C16, as well as B35 (susceptible), are also influential, but their effects are less robust. Influence of class II alleles was only observed for DR11. These results confirm the influence of the immune system on disease progression and may have implications on peptide-based vaccine development.     

谷子和狗尾草核型分析

作者研究了我国谷子(Setaria italica Beauv.)和狗尾草的核型与Giemsa带,两者核型基本相同,均为2n=18=14m+2sm+2st(SAT)。带型亦相近,另外在谷子和狗尾草中都发现有四倍体。     

Physiology of the ECL cells.

The enterochromaffin-like (ECL) cells of the oxyntic mucosa (fundus) of the stomach produce, store and secrete histamine, chromogranin A-derived peptides such as pancreastatin, and an unanticipated but as yet unidentified peptide hormone. The cells are stimulated by gastrin and pituitary adenylate cyclase activating peptide and suppressed by somatostatin and galanin. Choline esters and histamine seem to be without effect on ECL cell secretion. The existence of a gastrin-ECL cell axis not only explains how gastrin stimulates acid secretion but also may help to explore the functional significance of the ECL cells with respect to the nature and bioactivity of its peptide hormone. From the results of studies of gastrectomized/fundectomized and gastrin-treated rats, it has been speculated that the anticipated ECL-cell peptide hormone acts on bone metabolism.     

Experimental evidence of environmental effects on age-specific reproductive success: the importance of resource quality.

Age-specific access to high-quality resources (e.g. territory or nest site) might be an important determinant for improved reproductive performance with increasing age. I experimentally investigated the effects of territory quality versus other age-related improvements in breeding competence (e.g. foraging skills, breeding experience and local knowledge) on age-specific reproductive success. Territory quality (i.e. territory field layer height) was manipulated in year 2 of northern wheatears (Oenanthe oenanthe) that were breeding in the same territory in two consecutive years. Changing territory quality by changing field layer height had a strong effect on within-individual change in the reproductive success of wheatears. This effect was mainly due to a corresponding change in nest predation risk. When territory quality was kept constant (i.e. no between-year change in territory field layer height), within-individual reproductive success did not change between subsequent years. Thus, age-related improvements in foraging skills, breeding experience and local familiarity had no significant effect on within-individual changes in reproductive success. Increased reproductive success with increased age in northern wheatears is therefore mainly explained by an improved access to high-quality territories with increasing age. I conclude that age-dependent access to high-quality breeding resources might be a widespread phenomenon in nature.     

Responses of Mentha suspension-cultured cells to 2,4-dichlorophenoxyacetic acid and accumulation of esterified phenolic acids in their cell walls.

Two distinct types of cell growth of suspension-cultured Mentha were formed when the cells maintained in the medium containing 1000 micrograms l-1 2,4-D were subcultured into different 2,4-D concentrations. Few cell elongation of Mentha (average cell length: 34-40 microns) was observed after division in the medium containing 1-200 micrograms l-1 2,4-D; and significant cell elongation (average cell length: 95-130 microns) was observed after cell division in the medium containing 500-2000 micrograms l-1 2,4-D. A close correlation between culture medium and water content in the cells indicated that 2,4-D promoted cell elongation by water uptake. Amounts of phenolic acid in cell walls were much higher in unelongated cell walls than in elongated ones during the cultivation, and there was a close correlation between the amounts and the level of PAL activity in elongated and unelongated cells. However, there was no significant difference in cell wall components and its neutral sugar composition between elongated and unelongated cells.     

Change of hepatitis B virions (Dane particles) phosphorylation pattern by human hepatoma cell particulate fraction

Protein kinase activity has been found in hepatitis B virions (Dane particles) purified from the plasma of hepatitis B surface antigen carriers [Albin, C., and Robinson, W.S. (1980) J. Virol. 34, 297-302]. Dane particles were purified from the pooled, HBeAg-positive plasma. When this preparation was incubated with [gamma 32P]ATP in the presence of 10mM MnCl2 and 0.5% NP-40 for 15 seconds at 30 degrees C, several phosphorylated polypeptides of 20,000, 42,000, 48,000, 50,000 and 56,000 daltons were detected in sodium dodecyl sulfate-polyacrylamide gels. When the Dane particles were incubated with [gamma 32P]ATP, 10 mM MnCl2, and 0.5% NP-40 in the presence of human hepatoma cell (J-5) particulate fraction at 30 degrees C, 15 seconds, the 42,000, 48,000 and 50,000 daltons phosphorylated polypeptides were not found. When human peripheral blood lymphocytes particulate fraction was incubated with Dane particles under the same conditions, no change of Dane particle phosphorylated polypeptides was detected. Previous publications [Albin, C., and Robinson, W.S. (1980) J. Virol. 34, 297-302; Gerlich, W.H. et al. (1982) J. Virol. 42, 761-766] showed that when hepatitis B core particles purified from hepatoma tissues contained protein kinase activity, only phosphorylated polypeptide was 20,000 daltons. Our data suggested that when Dane particles were put in an environment of hepatoma cells (or tissues), the protein kinase could only phosphorylate selected polypeptides in these particles.     

Effects of ATP and cyclic AMP on the (Na+ + K+ + 2Cl-)-cotransport system in turkey erythrocytes

As turkey erythrocytes were progressively depleted of ATP by preincubation with dinitrophenol, the (Na+ + K+ + 2Cl-)-cotransport system (assayed by the bumetanide-sensitive fraction of 86Rb+ influx) became less responsive to activation. The dependence upon intracellular ATP concentration was significantly steeper for transport activated by hypertonic shock (halfmaximal activity at 0.7 mM ATP) than for that activated by either epinephrine or cyclic AMP (halfmaximal activity at 1.7 mM ATP). Upon removal of epinephrine or cyclic AMP from cells that had been preincubated with those substances, bumetanide-sensitive transport activity declined sharply, even though the intracellular cyclic AMP concentration was still over 10-fold that required to maximally activate the transport system. These data are in agreement with the notion that the (Na+ + K+ + 2Cl-)-cotransport system in turkey erythrocytes is activated by cyclic AMP, presumably through the 'classical' pathway involving a protein kinase. They do however indicate that some other, as yet undefined aspect of cyclic AMP metabolism is important for the maintenance of transport activity.