A chimeric ubiquitin conjugating enzyme that combines the cell cycle properties of CDC34 (UBC3) and the DNA repair properties of RAD6 (UBC2): implications for the structure, function and evolution of the E2s.

The CDC34 (UBC3) protein from Saccharomyces cerevisiae has a 125 residue tail that contains a polyacidic region flanked on either side by sequences of mixed composition. We show that although a catalytic domain is essential for CDC34 activity, a major cell cycle determinant of this enzyme is found within a 74 residue segment of the tail that does not include the polyacidic stretch or downstream sequences. Transposition of the CDC34 tail onto the catalytic domain of a functionally unrelated E2 such as RAD6 (UBC2) results in a chimeric E2 that combines RAD6 and CDC34 activities within the same polypeptide. In addition to the tail, the cell cycle function exhibited by the chimera and CDC34 is probably dependent on a conserved region of the catalytic domain that is shared by both RAD6 and CDC34. Despite this similarity, the CDC34 catalytic domain cannot substitute for the DNA repair and growth functions of the RAD6 catalytic domain, indicating that although these domains are structurally related, sufficient differences exist to maintain their functional individuality. Expression of the CDC34 catalytic domain and tail as separate polypeptides are capable of only partial function; thus, while the tail displays autonomous structural characteristics, there is considerable advantage gained when both domains coexist within the same polypeptide. The ability of these and other derivatives to restore partial function to a cdc34 temperature-sensitive mutant but not to a disruption mutant suggests that interaction between two CDC34 polypeptides is a requirement of CDC34 activity. Based on this idea we propose a model that accounts for the initiating steps leading to multi-ubiquitin chain synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

四川省西部鱼类寄生粘孢子虫——1.粘体虫属六新种(粘孢子纲:双壳目)

本文报导四川省西部鱼类寄生粘孢子虫粘体虫属六新种,即异型粘体虫,新种Myxosoma disparis sp.nov.,四川粘体虫,新种Myxosoma sichuanensis sp.nov.,光唇粘体虫,新种Myxosoma acrossochilusi sp.nov.鳅粘体虫,新种Myxosoma nemachilusi sp.nov.斜囊粘体虫,新种Myxosoma obliqua sp.nov.,雅安粘体虫,新种Myxosoma yaanensis sp.nov.。     

云南叶螨属一新种(蜱螨目:叶螨科)

在鉴定云南叶螨标本时,发现叶螨属一新种,现记述如下。模式标本保存于上海农学院。本文量度单位均为微米。 食禾叶螨Tetranychus graminivorus新种(图1—14) 雌螨 体长(包括喙)454,宽298。椭圆形。浅黄绿色。须肢端感器圆柱形,长6.8,     

中国东北地区常见有瓣蝇类调查初步报告

与人类杂处的蝇类,在我国东北地区的分布情况尚少系统调查。作者于1956年5月、8月曾赴内蒙东北部(伊图里河、图里河),6月、7月赴营口、盘山(田庄台),借这些机会,顺便采集了蝇类标本;同年9月组内同志去绥中也采回部分标本;1957年5月至10月作者又赴吉林、辽宁两省各地进行了蝇类调查。其中有瓣蝇类已经定名的共计5科26属68种,有6种为国内新记录。兹将结果报告如下:     

吉林省寄螨亚科三新种(啤螨目:寄螨科)

本文记述寄螨亚科(Parasitinae)三新种。模式标本保存于吉林省地方病第一防治研究所。文内测量单位为微米,括号内为测量平均值。     

Stress resistance in Saccharomyces cerevisiae is strongly correlated with assembly of a novel type of multiubiquitin chain.

The covalent attachment of ubiquitin (Ub) to short-lived or damaged proteins is believed to be the signal that initiates their selective degradation. In several cases, it has been shown that the proteolytic signal takes the form of a multi-Ub chain in which successive Ub molecules are linked tandemly at lysine 48 (K-48). Here we show that Ub molecules can be linked together in vivo at two other lysine positions, lysine 29 (K-29) and lysine 63 (K-63). The formation of these alternative linkages is strongly dependent on the presence of the stress-related Ub conjugating enzymes UBC4 and UBC5. Furthermore, expression of Ub carrying a K-63 to arginine 63 substitution in a strain of Saccharomyces cerevisiae that is missing the poly-Ub gene, UBI4, fails to compensate for the stress defects associated with these cells. Taken together, these results suggest that the formation of multi-Ub chains involving K-63 linkages plays an important role in the yeast stress response. In broader terms, these results also suggest that Ub is a versatile signal in which different Ub chain configurations are used for different functions.     

Regulation of μ-Opioid Receptor mRNA in Rat Globus Pallidus: Effects of Enkephalin Increases Induced by Short- and Long-Term Haloperidol Administration

Abstract: The mRNA encoding μ-opioid receptors is expressed in neurons of the globus pallidus, a region of the basal ganglia that receives a dense enkephalinergic innervation from the striatum. The regulation of the mRNAs encoding the opioid peptide enkephalin in the striatum and the μ-opioid receptor in the globus pallidus was examined with in situ hybridization histochemistry following short- or long-term haloperidol treatments, which alter striatal enkephalin mRNA levels. Animals were administered haloperidol daily for 3 or 7 days (1 mg/kg, s.c.) or continuously for 8 months (1 mg/kg, depot followed by oral). Enkephalin and μ-opioid receptor mRNA levels were unchanged after 3 days of haloperidol treatment. In contrast, the enkephalin mRNA level was increased in the striatum, and μ-opioid receptor mRNA levels were markedly decreased in the globus pallidus after 7 days of haloperidol administration. Similar effects were observed in rats treated with haloperidol for 8 months. The results provide the first evidence of regulation of μ-opioid receptor mRNA in vivo.     

嗜盐耐盐微生物抗盐胁迫相关离子转运蛋白研究进展

离子转运蛋白在维持细胞内pH稳态、离子动态平衡等方面发挥着重要作用。钠离子转运体和钾离子转运体在嗜盐耐盐微生物中广泛存在,其"保钾排钠"机制是微生物抗盐胁迫的两大策略之一。近年来,嗜盐耐盐微生物中许多新型钠、钾离子转运体被陆续发现,如RDD蛋白、UPF0118蛋白、DUF蛋白和KimA蛋白等;Fe³⁺、Mg²⁺等其他金属离子的转运蛋白也被证实可通过影响微生物胞内相容性溶质的合成起到渗透调节的作用。本文综述了嗜盐耐盐微生物中抗盐胁迫相关的各类离子转运蛋白,分析其分子结构和工作机理,并对这些蛋白在农业方面的应用进行了展望。继续发现新的离子转运蛋白,探究抗盐胁迫相关离子转运蛋白的结构和机理,解析各转运系统的协同作用及分子调控机制,将进一步加深对嗜盐耐盐微生物抗盐胁迫调控的认识,并为盐碱地农作物的改良等提供新的思路。