Dextran–estrone conjugate: synthesis and in vitro release study

A novel hormone conjugate has been prepared by a coupling reaction between modified estrone and dextran. In order to provide a suitable reactive estrone derivative for coupling with dextran and a spacer between the drug carrier and the hormone, the steroidal sex hormone was succinylated by reaction with succinic anhydride. Subsequently, the carboxylic acid terminal of succinylated estrone was further reacted with thionyl chloride to replace the hydroxy group with chlorine to make a better leaving group. The ester bond was employed as labile linkage between the hormone and the biopolymer carrier backbone so that the coupled estrogen could be released from the conjugate via ester hydrolysis. Structures of the modified estrone and dextran–estrone conjugate were determined by elemental analysis and by FTIR, ¹H and ¹³C NMR spectroscopies. The degree of substitution (D.S.) per anhydroglucose (AHG) unit was 0.33 (11.0 mol-% of estrone moieties), as calculated from the ¹H NMR spectrum. In vitro hydrolysis of the conjugate in aqueous phosphate buffer/ethanol solutions at pH 8.0 and 7.4 and 37°C released estrone was completed within a few days and followed zero-order kinetics.     

A mechanism for the establishment of polar cell morphology based on the cytoskeleton-derived forces exerted on the cell boundary

A mechanism for the establishment of polar cell morphology is presented, based on the internal forces that the cytoskeletal structures exert on the cell boundary. Cell shapes are determined by postulating that they correspond to the minimum of the total energy of the system, which is the sum of the bending energy of the cell boundary and the potential energies of the involved forces. Axisymmetrical cell shapes are considered, and it is assumed that the cytoskeletal structures exert an extensional axial force and are involved in controlling the area of the cell boundary. The dependence of cell shapes on the axial force is presented for different values of this area. The results show that, at increasing axial force, the cell undergoes a discontinuous transition from an oval shape, exhibiting an equatorial mirror symmetry into a polar shape. The proposed mechanism is related to previously documented specific effects of microtubule- and actin-modifying drugs on polar shapes of developing isolated retinal photoreceptor cells. Received: 28 January 1998 / Revised version: 25 July 1998 / Accepted: 29 July 1998     

美洲商陆核基因组抗病毒蛋白基因的克隆及序列分析

通过ＰＣＲ扩增,从美洲商陆（Ｐｈｙｔｏｌａｃａａｍｅｒｉｃａｎａ）核基因组中克隆了商陆抗病毒蛋白基因,序列分析表明,该基因含８８５个核苷酸,与已报道的序列比较,核苷酸同源性为９９．３％。     

High- and low-affinity GABA-receptors in cultured cerebellar granule cells regulate transmitter release by different mechanisms

The ability of high- and low-affinity GABA_A-receptors, respectively to inhibit depolarization coupled transmitter release was studied in cultured glutamatergic cerebellar granule cells which, depending on the culture conditions, express either high-affinity GABA_A-receptors alone or high-affinity receptors together with low-affinity receptors. In order to gain information about the coupling of these receptors to chloride channels the effect of picrotoxin and binding of [³⁵S]t-butylbicyclophosphorothionate, both of which interact specifically with such channels were studied. Moreover, the influence of Flunitrazepam on the GABA-mediated inhibition of transmitter release was investigated to see if the GABA-receptors are coupled to benzodiazepine binding sites. Under conditions where the granule cells express only high-affinity GABA_A-receptors it was found that GABA was able to inhibit transmitter release elicited by mild depolarization induced either by 30 mM KCl or 25 μM glutamate. This effect of GABA could be enhanced by Flunitrazepam and blocked by picrotoxin. However, transmitter release from these neurones induced by a more pronounced depolarization (55 mM KCl) could not be inhibited by GABA. Under conditions where the neurons express both high- and low-affinity GABA_A-receptors transmitter release elicited by 55 mM KCl could be inhibited by GABA but this inhibitory effect of GABA could not be blocked by picrotoxin, nor could it be enhanced by Flunitrazepam. These results strongly suggest that while the action of the high-affinity GABA_A-receptors is coupled to chloride channels and benzodiazepine binding sites, the physiological action of the low-affinity GABA_A-receptors is not. This lack of coupling between the low-affinity GABA_A-receptors and chloride channels is further supported by the finding that the K_D and B_max values for [³⁵S]TBPS binding to the granule cells were independent of whether or not the cells expressed low-affinity GABA_A-receptors. While the results clearly show that the inhibitory action of GABA mediated by low-affinity GABA_A-receptors is not coupled to chloride channels, the exact mechanism of action of these receptors still remains to be elucidated.     

广西姑婆山及邻近地区大型真菌物种多样性

姑婆山紧邻南岭生物多样性保护优先区，孕育了丰富的生物资源。为了解该区域大型真菌物种多样性，该文采用随机踏查法对广西姑婆山自治区级自然保护区(以下简称姑婆山)及邻近地区大型真菌资源进行调查采集，并结合形态学和分子生物学方法进行物种鉴定。结果表明：(1)共发现348种大型真菌，隶属于2门6纲17目69科175属，其中包含食用菌40种、药用菌42种、毒菌7种。(2)对该区的物种组成分析表明，优势科为蘑菇科(Agaricaceae)、牛肝菌科(Boletaceae)、粉褶蕈科(Entolomataceae)和锈革菌科(Hymenochaetaceae)等9科；优势属为鹅膏属(Amanita)、靴耳属(Crepidotus)、毛皮伞属(Crinipellis)和粉褶蕈属(Entoloma)等11属。(3)共发现2个中国特有属，即脆孔菌属(Fragiliporia)和臧氏牛肝菌属(Zangia);11个中国特有种，即厚集毛菌(Coltricia crassa)、魏氏集毛菌(C.weii)、丛生粉褶蕈(Entoloma caespitosum)、极细粉褶蕈(E.praegracile)、近薄囊粉褶蕈...     

Osmoregulated periplasmic glucans are needed for competitive growth and biofilm formation by Salmonella enterica serovar Typhimurium in leafy-green vegetable wash waters and colonization in mice

Osmoregulated periplasmic glucans (OPGs) are major periplasmic constituents of Gram-negative bacteria. The role of OPGs has been postulated in symbiotic as well as pathogenic host–microorganism interactions. Here, we report the role of OPGs from Salmonella enterica serovar Typhimurium during growth and biofilm formation in leafy-green vegetable wash water. The opgGH mutant strain, which was defective in OPG biosynthesis, initiated the growth at a slower rate in wash waters obtained from spinach, lettuce and green collard and severely impaired biofilm formation. The lack of OPG synthesis did not influence biofilm formation by the opgGH mutant in low-nutrient low-osmolarity laboratory media. In coculture experiments initiated with equal proportions of cells, the opgGH mutant was outnumbered by the wild-type strain under the planktonic as well as the biofilm growth conditions. The opgGH mutant strain poorly colonized mouse organs when introduced orally along with the wild-type strain. This is the first report demonstrating the role of OPGs of Salmonella in competitive colonization of biofilms, planktonic cultures and mouse organs.     

Fossil woods from the Lower Coal-bearing Formation of the Janggi Group (Early Miocene) in the Pohang Basin,Korea

Fourteen species of fossil wood belonging to eleven genera and seven families were identified from 38 well preserved specimens collected from the Lower Coal-bearing Formation of Janggi Group at Donghae-myeon, Pohang City, Gyeongsangbuk-do Prefecture, Korea. Seven new taxa were found and described; they are Carya koreana Jeong et Kim, Betula janggiensis Jeong et Kim, Carpinus donghaensis Jeong et Kim, Ostrya geumgwangensis Jeong et Kim, Stewartia pseudo-camellioxylon Jeong et Kim, Acer minokamoensis Jeong, Kim et Suzuki and Acer pohangensis Jeong et Kim. The most abundant taxa are Betulaceae, Aceraceae, Ulmaceae, and Wataria. Except Wataria of which the habitat preference has not been confirmed, these taxa are major elements of cool-temperate vegetation and are similar to the Aniai-type flora of Japan. Previous studies of fossil plants from the Geumgwangdong Shale (leaves and seeds), the Upper Coal-bearing Formation (fossil woods) and the Yeonil Group (leaves and seeds) and this study, show that the climate of the Pohang Basin changed from cool-temperate to warm-temperate and subtropical during the Miocene.     

Assessing chimpanzee personality and subjective well‐being in Japan

We tested whether the cultural background of raters influenced ratings of chimpanzee personality. Our study involved comparing personality and subjective well‐being ratings of 146 chimpanzees in Japan that were housed in zoos, research institutes, and a retirement sanctuary to ratings of chimpanzees in US and Australian zoos. Personality ratings were made on a translated and expanded version of a questionnaire used to rate chimpanzees in the US and Australia. Subjective well‐being ratings were made on a translated version of a questionnaire used to rate chimpanzees in the US and Australia. The mean interrater reliabilities of the 43 original adjectives did not markedly differ between the present sample and the original sample of 100 zoo chimpanzees in the US. Interrater reliabilities of these samples were highly correlated, suggesting that their rank order was preserved. Comparison of the factor structures for the Japanese sample and for the original sample of chimpanzees in US zoos indicated that the overall structure was replicated and that the Dominance, Extraversion, Conscientiousness, and Agreeableness domains clearly generalized. Consistent with earlier studies, older chimpanzees had higher Dominance and lower Extraversion and Openness scores. Correlations between the six domain scores and subjective well‐being were comparable to those for chimpanzees housed in the US and Australia. These findings suggest that chimpanzee personality ratings are not affected by the culture of the raters. Am. J. Primatol. 71:283–292, 2009. © 2009 Wiley‐Liss, Inc.