国内九种食用菌营养构成的分析

本文通过对全国第二届农业博览会参评的九种食用菌３９个样品的蛋白质、氨基酸等的测定,按照食用菌蛋白质的营养价值的评定标准,对其营养价值进行了评价。初步探讨了国内食用菌生产加工中存在的不足及改进的方向。     

Crystal structure determination of alkaline haemorrhagin AaH III from snake venom ofAgkistrodon acutus

The haemorrhagin AaH III isolated from the snake venom ofAgkistrodon acutus is one of the few alkaline ones in snake venoms. Its crystals belong to space group P2₁2₁2₁ witha = 9. 573 4 nm,b = 4. 996 7 nm andc = 4.728 8 nm. Its crystal structure was determined by the molecular replacement method according to the model of metalloproteinase Adamalysin II from eastern rattlesnake venom. The AaH III structure has been refined by PROLSQ. The finalR factor was 0.254 and the RMS deviations of bond lengths and angles were 0.001 8 nm and 1.5°. The structure comparison suggested that AaH III has a similar structure to other snake venom zinc-metalloproteinases. They all belong to matrix metalloproteinases super-family.     

2D 1H and 3D 1H-15N NMR of zinc-rubredoxins: contributions of the beta-sheet to thermostability.

Based on 2D 1H-1H and 2D and 3D 1H-15N NMR spectroscopies, complete 1H NMR assignments are reported for zinc-containing Clostridium pasteurianum rubredoxin (Cp ZnRd). Complete 1H NMR assignments are also reported for a mutated Cp ZnRd, in which residues near the N-terminus, namely, Met 1, Lys 2, and Pro 15, have been changed to their counterparts, (-), Ala and Glu, respectively, in rubredoxin from the hyperthermophilic archaeon, Pyrococcus furiosus (Pf Rd). The secondary structure of both wild-type and mutated Cp ZnRds, as determined by NMR methods, is essentially the same. However, the NMR data indicate an extension of the three-stranded beta-sheet in the mutated Cp ZnRd to include the N-terminal Ala residue and Glu 15, as occurs in Pf Rd. The mutated Cp Rd also shows more intense NOE cross peaks, indicating stronger interactions between the strands of the beta-sheet and, in fact, throughout the mutated Rd. However, these stronger interactions do not lead to any significant increase in thermostability, and both the mutated and wild-type Cp Rds are much less thermostable than Pf Rd. These correlations strongly suggest that, contrary to a previous proposal [Blake PR et al., 1992, Protein Sci 1:1508-1521], the thermostabilization mechanism of Pf Rd is not dominated by a unique set of hydrogen bonds or electrostatic interactions involving the N-terminal strand of the beta-sheet. The NMR results also suggest that an overall tighter protein structure does not necessarily lead to increased thermostability.     

银杏精子细胞生毛体及其它细胞器的超微结构

生毛体与嗜锇颗粒是银杏 (Ginkgobiloba)精子细胞中最具有标志性的结构。生毛体是细胞质内一直径为 3～ 4μm的圆球形结构 ,它由一个电子致密的核心和由此向周边发散出的辐射状中心粒组成 ,致密核心上具有微管结构的弱电子染色区域 ,并有微管从生毛体延伸到细胞质。嗜锇颗粒直径为 1 0～ 2 0μm,呈圆球状 ,位于生毛体和细胞核之间 ,其相对的另一侧存在纤维颗粒体。在精子细胞质内 ,特别是嗜锇颗粒和生毛体周围线粒体、质体、内质网、高尔基体等细胞器丰富。银杏精子细胞核较大 ,在细胞核内 ,核仁结构呈球形 ,电子染色致密的颗粒区在周围 ,而纤维组分则在圆球的中间。在核膜表面布满了分布不均匀的核孔复合体。     

Ribose biosynthesis and evidence for an alternative first step in the common aromatic amino acid pathway in Methanococcus maripaludis.

An acetate-requiring mutant of Methanococcus maripaludis allowed efficient labeling of riboses following growth in minimal medium supplemented with [2-(13)C]acetate. Nuclear magnetic resonance and mass spectroscopic analysis of purified cytidine and uridine demonstrated that the C-1' of the ribose was about 67% enriched for 13C. This value was inconsistent with the formation of erythrose 4-phosphate (E4P) exclusively by the carboxylation of a triose. Instead, these results suggest that either (i) E4P is formed by both the nonoxidative pentose phosphate and triose carboxylation pathways or (ii) E4P is formed exclusively by the nonoxidative pentose phosphate pathway and is not a precursor of aromatic amino acids.     

Substrate type and microbial interactions as factors affecting ascocarp formation by mangrove fungi

The growth and ascocarp formation of Aigialus parvus, Lignincola laevis and Verruculina enalia in single and mixed cultures on wood of Avicennia alba, Bruguiera cylindrica and Rhizophora apiculata was studied. In pure cultures, these fungi grew well on all three species of wood. Except for Aigialus parvus on B. cylindrica, all three fungi also formed abundant ascocarps. The time needed for ascocarp formation after inoculation ranged from six to eight weeks for L. laevis on all wood species, and for V. enalia on Avicennia alba; to ten weeks for V. enalia on B. cylindrica and R. apiculata; and 12 weeks for Aigialus parvus on Avicennia alba and R. apiculata.Mixed cultures involving two or three of the test fungi delayed the onset of sporulation and affected the abundance of ascocarps formed. Sporulation by Aigialus parvus on Avicennia alba and R. apiculata was markedly reduced by L. laevis alone or in combination with V. enalia. Likewise, sporulation by L. laevis was suppressed by Aigialus parvus and/or V. enalia. In contrast, the presence of L. laevis enhanced ascocarp formation by V. enalia on all types of wood. These observations suggest the presence of interference competition among the test fungi.     

In vitro assembly of an archaeal D-L-N RNA polymerase subunit complex reveals a eukaryote-like structural arrangement.

Archaeal RNA polymerases (RNAPs) resemble the eukaryotic nuclear RNAPs in complexity, and many of their subunits display a high degree of sequence similarity to their eukaryotic counterparts. Here we describe specific protein-protein contacts present between individual recombinant RNAP subunits from the archaeon Methanococcus jannaschii. Subunits D and L interact specifically with each other in two-hybrid assays. D also interacts under the same conditions with the RPB11 and AC19 subunits from the yeast Saccharomyces cerevisiae, suggesting that essential elements of the binding surface between these proteins have been conserved across the archaeal/eukaryotic evolutionary domain boundary. Interactions between L and RPB3 or AC40 were, however, not detectable. Recombinant D and L subunits associate under in vitro conditions and copurify with each other during size-exclusion chromatography. Addition of an another recombinant subunit (N) to the D-L complex results in the formation of a triple complex. This D-L-N complex resembles the RPB3-RPB11-RPB10 or AC40-AC19-RPB10 complexes in eukaryotic RNAPIIand RNAPI/RNAPIII, respectively. Our data provide evidence for a close similarity in the quaternary arrangement of a subset of archaeal and eukaryotic RNA polymerase subunits and the conservation of the protein-protein contacts formed between them.     

Synthesis and antiplatelet, antiinflammatory, and antiallergic activities of substituted 3-chloro-5,8-dimethoxy-1,4-naphthoquinone and related compounds

2-Amino (6), 2-alkylamino (7–8), 2-methoxy (9), 2-acetamido (10), and 5,8-diacetoxy (11) derivatives of the lead compound 2,3-dichloro-5,8-dimethoxy-1,4-naphthoquinone (4) were synthesized, together with 6,7-dichloro-5,8-dimethoxy-1,4-naphthoquinone (5), a positional isomer of 4. Antiplatelet, antiinflammatory, and antiallergic activities were evaluated, and most compounds were quite potent in all assays. Compounds 5 and 9–11 were especially active; however, 5 was ineffective against neutrophil superoxide formation, and 10 was ineffective against mast cell degranulation.     

芫荽花蜜腺的发育解剖学研究

芫荽的花蜜腺位于子房上部盘状结构上,属于下位子房上部的花盘蜜腺。蜜腺由分泌表皮和产蜜组织构成。分泌表皮具厚的呈波纹状皱折的角质层,层皮上分布有下陷的变态气孔。产蜜组织细胞４－５层,其下有３－４层大型薄壁细胞与来自子房壁的维管束相毗邻。芫荽花蜜腺发育较晚,在子房发育后期由花盘表面的１－２层细胞恢复分裂能力形成蜜腺组织。产蜜组织细胞在发育过程中,液泡、淀粉粒都呈现一定的消第长规律。根据其结构及泌蜜前后     

硅酸盐细菌和苏云金芽孢杆菌原生质体融合

具有解钾活性的硅酸盐细菌──胶质芽孢杆菌（R．mucilaginesus）W9－12与具有杀虫活性的苏云金芽孢杆菌（B．thuringensis）Bt179208原生质体质进行了融合。W9－12原生质体形成率为99．7％．再生率为24．9％,Bt179208原生质体形成率为99．9％,再生率为35％。以PEG为助融剂进行原生质体融合．得到56个融合子．融合率为5．92×10－6。融合子在双抗选择培养基上连续传代10次,得到12个稳定的融合子,生物测定表明,融合子既具有一定的杀虫活性又具有一定的解钾活性。