Selective inhibition of prostaglandin biosynthesis by gold salts and phenylbutazone

Gold salts and phenylbutazone selectively inhibit the synthesis of PGF_2α and PGE₂ respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE₂ and PGF_2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function.     

Radiation of the Tnt1 retrotransposon superfamily in three Solanaceae genera

Background  

Tnt1 was the first active plant retrotransposon identified in tobacco after nitrate reductase gene disruption. The Tnt1 superfamily comprises elements from Nicotiana (Tnt1 and Tto1) and Lycopersicon (Retrolyc1 and Tlc1) species. The study presented here was conducted to characterise Tnt1-related sequences in 20 wild species of Solanum and five cultivars of Solanum tuberosum.     

Studies on the Preparation,Isolation, and Reactions of Adenosine Schiff Bases

Abstract

A systematic study of the preparation, isolation, and reactions of adenosine Schiff bases is presented. Schiff bases of nucleosides can be prepared and isolated, but the reaction appears to be specific for 2′, 3′-0-isopropylidene adenosines. The use of nucleoside Schiff bases as synthetic intermediates is not yet a viable process.     

Synthesis,proapoptotic screening,and structure–activity relationships of novel aza-lupane triterpenoids

Apoptosis is a highly regulated process by which excessive cells are eliminated in order to maintain normal cell development and tissue homeostasis. Resistance to apoptosis often contributes to failure in cancer prevention and treatment. Apoptotic cell death regulators are considered important targets for discovery and development of new therapeutic agents in oncology research. A class of novel aza-lupane triterpenoids were designed, synthesized, and evaluated for antitumor activity against a panel of cancer cell lines of different histogenic origin and for ability to induce apoptosis. 3,30-Bis(aza) derivatives were identified not only to possess improved cytotoxicity compared to the natural product betulinic acid but also to affect cell death predominantly via apoptosis, whereas the mono(aza) derivatives apparently triggered cell death via different, non-apoptotic pathway(s).     

Expression,localization and possible functions of aquaporins 3 and 8 in rat digestive system

Although aquaporins (AQPs) play important roles in transcellular water movement, their precise quantification and localization remains controversial. We investigated expression levels and localizations of AQP3 and AQP8 and their possible functions in the rat digestive system using real-time polymerase chain reactions, western blot analysis and immunohistochemistry. We investigated the expression levels and localizations of AQP3 and AQP8 in esophagus, forestomach, glandular stomach, duodenum, jejunum, ileum, proximal and distal colon, and liver. AQP3 was expressed in the basolateral membranes of stratified epithelia (esophagus and forestomach) and simple columnar epithelia (glandular stomach, ileum, and proximal and distal colon). Expression was particularly abundant in the esophagus, and proximal and distal colon. AQP8 was found in the subapical compartment of columnar epithelial cells of the jejunum, ileum, proximal colon and liver; the most intense staining occurred in the jejunum. Our results suggest that AQP3 and AQP8 play significant roles in intestinal function and/or fluid homeostasis and may be an important subject for future investigation of disorders that involve disruption of intestinal fluid homeostasis, such as inflammatory bowel disease and irritable bowel syndrome.     

Müllerian inhibiting substance regulates its receptor/SMAD signaling and causes mesenchymal transition of the coelomic epithelial cells early in Müllerian duct regression

Examination of Müllerian inhibiting substance (MIS) signaling in the rat in vivo and in vitro revealed novel developmental stage- and tissue-specific events that contributed to a window of MIS responsiveness in Müllerian duct regression. The MIS type II receptor (MISRII)-expressing cells are initially present in the coelomic epithelium of both male and female urogenital ridges, and then migrate into the mesenchyme surrounding the male Müllerian duct under the influence of MIS. Expression of the genes encoding MIS type I receptors, Alk2 and Alk3, is also spatiotemporally controlled; Alk2 expression appears earlier and increases predominantly in the coelomic epithelium, whereas Alk3 expression appears later and is restricted to the mesenchyme, suggesting sequential roles in Müllerian duct regression. MIS induces expression of Alk2, Alk3 and Smad8, but downregulates Smad5 in the urogenital ridge. Alk2-specific small interfering RNA (siRNA) blocks both the transition of MISRII expression from the coelomic epithelium to the mesenchyme and Müllerian duct regression in organ culture. Müllerian duct regression can also be inhibited or accelerated by siRNA targeting Smad8 and Smad5, respectively. Thus, the early action of MIS is to initiate an epithelial-to-mesenchymal transition of MISRII-expressing cells and to specify the components of the receptor/SMAD signaling pathway by differentially regulating their expression.     

海洋浮游藻类细胞质膜氧化还原活性与细胞外CA活性的关系

海洋浮游藻类除通过吸收和释放分子与离子来改变其环境的化学成分外,还可通过细胞外表面一些酶的作用引起质膜外化学物质变化。在这方面,海洋浮游藻类一个主要的细胞外表面酶-碳酸酐酶(CA),在经胰蛋白酶处理从细胞质膜上释放出来后,仍保留其催化活性。当细胞外表面CA(简称细胞外CA)具活性时,可催化质膜外HCO_3~-与CO_2的相互转化,为Rubisco(磷酸核酮糖羧化酶)提供一稳定的CO_2流量环境,以维持正常的光合作用。