Elongation factor 1α genes of the red alga Porphyra purpurea include a novel, developmentally specialized variant

The life cycle of the red alga Porphyra purpurea alternates between two morphologically distinct phases: a shell-boring, filamentous sporophyte and a free-living, foliose gametophyte. From a subtracted cDNA library enriched for sporophyte-specific sequences, we isolated a cDNA encoding an unusual elongation factor 1 (EF-1) that is expressed only in the sporophyte. A second EF-1 gene that is expressed equally in the sporophyte and the gametophyte was isolated from a genomic library. These are the only EF-1 genes detectable in P. purpurea. The constitutively expressed gene encodes and EF-1 very similar to those of most eukaryotes. However, the sporophyte-specific EF-1 is one of the most divergent yet described, with nine insertions or deletions ranging in size from 1 to 26 amino acids. This is the first report of a developmental stage-specific EF-1 outside of the animal kingdom and suggests a fundamental role for EF-1 in the developmental process.     

应用MUCAP试剂快速检测沙门氏菌

报告了用4-甲基伞形酮辛酯(4-Methylumbelliferyl-caprylate, MUCAP)快速检测沙门氏菌的特异性、敏感性和实用性。经HE,DHL,SS和麦康凯琼脂平板分离的65株沙门氏菌标准菌株和48株从食品中分离的沙门氏菌,用MUCAP测试均呈阳性反应;394株非沙门氏菌中呈阳性反应的假单胞菌、气单胞菌、邻单胞菌可通过氧化酶试验与沙门氏菌区分开;与粘质沙雷氏菌的交叉反应改用加1％蔗糖的分离平板也可排除。此方法的敏感性和特异性均达到97％以上,而且操作简便、快速,数分钟内即可完成。     

兔核移植胚胎起始发育的超微结构研究

对兔核移植胚胎起始发育的超微结构变化进行电镜观察,并与供体桑椹胚细胞,受体卵母细胞及同期正常受精胚胎的超微结构进行比较,“原核”期兔核移植胚胎的超微结构明显不同于供体桑椹胚细胞及受体卵母细胞的超微结构,而与同期正常受精胚胎相似,但有些核移植胚胎中皮质反应,及核仁和线粒体中出电子致密的网眼结构,与正常受精卵存在差别,分裂至２－细胞期时,与正常２－细胞胚超微结构更相似,结果提示,兔胚胎细胞核移植后,供     

猪精子凝集素的纯化,性质及其作用

用胎球蛋白－Ｓｅｐｈａｒｏｓｅ亲和层析和凝胶过滤层析从精子和精浆中分离纯化了猪精子凝集素（简称ＢＳＬ）。ＢＳＬ的血凝活性只被若干糖蛋白和聚糖所抑制。ＢＳＬ的分子量为５６ｋｄ,由分子量分别为１３．６ｋｄ（β）和１６．０ｋｄ（α）的两个不同的亚基以α１β３所组成。ＢＳＬ为糖蛋白,含中性糖３．２％,不含唾液酸。用ＥＬＩＳＡ法测定猪精子中ＢＳＬ的含量及分布,表明７０％嵌入在精子膜中,２５％结合在精子表面,     

有机硅橡胶固定化细胞进行的生物转化

有机硅橡胶固定化细胞进行的生物转化潘冰峰,戴学倩,冯青,李祖义（中国科学院上海有机化学研究所,２０００３２）关键词硅橡胶;白地霉;固定化细胞;生物转化近年来,有机化学领域的一个重要进展是用酶或微生物进行生物转化反应。其中研究和应用较多的是碳基还原,特...     

利福霉素生产菌产生钝化RifSV物质的分离及性质研究

利福霉素ＳＶ（简称ＲｉｆＳＶ）生产菌──地中海拟无枝菌酸菌在生物合成ＲｉｆＳＶ过程中,产生一种能钝化自身产物（ＲｉｆＳＶ）的物质．实验证实,该物质是由谷氨酸、天冬氨酸、赖氨酸及缬氨酸等１４种常见氨基酸组成的蛋白质．分子量（ＭＷ）约２．５×１０４Ｄ,等电点（ＰＩ）为５．７—６．１．在１００℃下加热１０ｍｉｎ,其活性丧失．作用于ＲｉｆＳＶ的最适ｐＨ值范围为７．４—８．６,最适温度为２９℃,初步证实该物质是一种酶（暂称利福霉素钝化酶）     

汉防己甲素及克矽平对矽肺大鼠Ⅰ型和Ⅲ型胶原mRNA的影响

汉防己甲素（汉甲）及克矽平（Ｐｏｌｙｖｉｎｙｌｐｙｒｉｄｉｎｅ－Ｎ－Ｏｘｉｄｅ,ＰＶＮＯ）是目前较为有效的抑制矽肺纤维化的药物。本文研究了其对胶原ｍＲＮＡ水平的影响．斑点杂交实验表明大鼠接尘６０天和１２０天后α１（Ⅰ）及α１（Ⅲ）ｍＲＮＡ水平明显上升,经汉甲或克矽平治疗１个月或３个月后,胶原ｍＲＮＡ水平明显下降。原位杂交结果表明胶原ｍＲ－ＮＡ银颗粒与细胞性结节和增厚的肺泡壁的成纤维细胞分布重合。汉甲或克矽平治疗后银颗粒数下降。提示汉甲及克矽平对矽肺进程中的胶原基因表达增强有抑制作用。     

天麻中抗真菌蛋白质的诱导和积累

前曾报告从天麻（Ｇａｔｒｏｄｉａ ｅｌａｔａ Ｂｌ）中分离出一种对木霉丝生长有强抑制作用的蛋白质,命名为天麻抗真菌蛋白,简称ＧＡＦＰ,也称为Ｇａｓｔｒｏｄｉａｎｉｎ。对不同天麻材料来源的ＧＡＦＰ分析表明：ＧＡＦＰ的相对分量为１４ｋＤ,等电点可能不同,变动范围８．１－９．３。体外抑菌试验证明ＧＡＦＰ对腐生性真菌如木霉如木霉和密环菌等有强抑制活性,半抑制浓度ＩＣ０．５为０．０８ｍｇ／ｍＬ;对寄生免疫荧     

ISOLATION AND CHARACTERIZATION OF PHASE-SPECIFIC COMPLEMENTARY DNAs FROM SPOROPHYTES AND GAMETOPHYTES OF PORPHYRA PURPUREA (RHODOPHYTA) USING SUBTRACTED COMPLEMENTARY DNA LIBRARIES1

The red alga Porphyra purpurea (Roth) C. Agardh has a life cycle that alternates between shell-boring, filamentous sporophytes and free-living, foliose gametophytes. The significant morphological differences between these two phases suggest that many genes should be developmentally regulated and expressed in a phase-specific manner. In this study, we prepared and screened subtracted complementary DNA (cDNA) libraries specific for the sporophyte and gametophyte of P. purpurea. This involved the construction of cDNA libraries from each phase, followed by the removal of common clones through subtractive hybridization. Sampling of the subtracted libraries indicated that 8–10% of the recombinant colonies in each library were specific for the appropriate phase. Of 20 putative phase-specific cDNAs selected from each subtracted library, eight unique clones were obtained for the sporophyte and seven for the gametophyte. After confirming their phase-specificities by hybridization to gametophyte and sporophyte messenger RNA, these 15 phase-specific cDNAs were sequenced, and the deduced amino acid sequences were used to search protein databanks. Two proteins encoded by the sporophyte-specific cDNAs and two by the gametophyte-specific cDNAs were identified by their similarity to databank entries.     

Structure—activity studies leading to potent chloride channel blockers: 5e-tert-butyl-2-[4-(substituted-ethynyl)phenyl]-1,3-dithianes

5e-tert-Butyl-2e-[4-(substituted-ethynyl)phenyl]-1,3-dithianes with selected functional groups (R) on the ethynyl moiety are potent blockers of the GABA-gated chloride channel measured as inhibitor concentration (IC₅₀) for 4-n-[³H]propyl-1-(4-ethynylphenyl)-2, 6,7-trioxabicyclo[2.2.2]octanebinding to bovine brain membranes. The terminal R substituents were introduced by coupling 5e-tert-butyl-2e-(4-iodophenyl)-1,3-dithiane with HC ≡ CR or 5e-tert-butyl-2e-(4-ethynylphenyl)-1,3-dithiane with XR. The potency of the parent compound (R=H) with an IC₅₀ of 21 μM is equaled or exceeded by up to 7-fold (i.e. IC₅₀ = 3–21 μM) by several carboxylic acids [R = (CH₂)_nCO₂H (n = 0–3), (CH_2nOCH₂CO₂H (n = 1–3) and CH₂SCH₂ CO₂H] and their esters and two phosphonic acids (CH₂CH₂PO₃H₂ and CH₂OCH₂PO₃H₂) but not their esters. These carboxyl and phosphonic acids (and their salts) include the most potent water-soluble chloride channel blockers known. Conversion to the monosulfones increases activity of the R = H and CH₂OH analogs by 1.2- to 3-fold but decreases that of the R = CH₂CH₂CO₂R′ (R′ = H or CH₃) derivatives by 3- to 13-fold. Quantitative structure-activity analyses for 44 2-[4-(substituted-ethynyl)phenyl]-dithianes suggests that the principal feature of the R substituent for high activity is its polarizable volume modeled as molecular refractivity, i.e. this substituent is not a well-defined pharmacophore and undergoes a structurally non-specific interaction with the receptor. These observations lay the background for preparing candidate affinity probes.