倭竹属地理分布的研究

倭竹属Shibataea Makino隶于禾本科之竹亚科,现已知有8种,分布于我国东南部的浙江、福建、江苏、安徽、江西等省,广东、台湾两省有少量栽培,日本产1种。苏联、西德、印尼等国所栽培的倭竹均系自我国或日本引入。我国浙-闽地区产8种,且都有野生发现,是本属的现代分布中心。倭竹属植物体型矮小,常植于庭院或公园中供观赏。近年来盆景艺术迅速发展,微型园林日益兴起,倭竹属植物体态优美,常绿,耐寒且易于栽培,为广大园林工作者所垂青。     

A dominant Th epitope in influenza nucleoprotein. Analysis of the fine specificity and functional repertoire of T cells recognizing a single determinant.

The sequence 260-283 of the nucleoprotein (NP) of influenza A virus is an epitope recognized by virus-immune lymph node cells from CBA (H-2k), B6 (H-2b), and B10.S (H-2s) mice. Further analysis shows that there are at least two Th epitopes within this sequence: the one close to the N-terminal (p260-273) is recognized by T cells from CBA and B6 mice while that close to the carboxyl-terminal (p270-283) is a dominant Th determinant in B10.S mice. The fine specificity of the recognition of this epitope by NP-specific T cell clones is also studied. When B10.S mice were infected intranasally or i.v. with live influenza virus, or immunized by different ways with various Ag preparations, P270-283 persistently emerged as a dominant T cell epitope. Immunization of B10.S mice with peptide p270-283 induces T cells with different in vivo functions including class II-restricted cytotoxicity, cognate help for Ag-specific antibody synthesis and delayed type hypersensitivity. This may have important implications for the understanding of the differentiation and classification of subsets of CD4+ T cells. The corresponding sequence of the NP of an equine influenza virus, A/Eq/Prague/56, which has a substitution (leucine to proline) at position 283, was not recognized by the lymph node cells from mice primed with either A/Okuda or A/Eq/Prague. However, the peptide, p270-283(E), representing this sequence induced T cell responses to both human and equine viruses. The data are discussed with respect to the development of viral vaccines.     

Serine-palmitoyl transferase activity in cultured human keratinocytes

Sphingolipids comprise approximately 25% of the stratum corneum lipids and are considered critical constituents of the epidermal permeability barrier. Whether sphingoid base structures are synthesized in the epidermis or whether they are derived from circulating or dermal sources is not known. We report here the initial characterization of serine-palmitoyl transferase (EC 2.3.1.50; SPT), the rate-limiting enzyme in the synthesis of sphingolipids, from cultured human neonatal keratinocytes. Subcellular fractionation studies demonstrated that 79% of the total cellular SPT activity was associated with the microsomes. The specific activity of keratinocyte SPT was 270 +/- 20 pmol/min per mg of microsomal protein, a level significantly higher than activities reported in other tissues. Keratinocyte SPT showed an apparent Km for L-serine of 0.40 (+/- 0.04 mM, with an alkaline pH optimum (8.2 +/- 0.4). Keratinocyte SPT utilizes palmitoyl-CoA preferentially over other saturated or unsaturated acyl-CoA substrates; increasing acyl-CoA chain lengths above C16 by one or two carbons was less detrimental to activity than similar decrements in chain length. Finally, the mechanism-based inhibitors L-cycloserine and beta-chloro-L-alanine, demonstrated potent inhibition of keratinocyte SPT activity, with 50% inhibitory concentrations of approximately 3.0 and 25 microM, respectively. In summary, we have found that cultured human neonatal keratinocytes contain unusually high levels of serine-palmitoyl transferase activity, and that the substrate specificity of keratinocyte SPT may determine the base composition of epidermal sphingolipids.     

Apolipoprotein E localization in rat hepatocytes by immunogold labeling of cryothin sections

The distribution of apolipoprotein (apo) E in rat hepatocytes was investigated with an affinity-purified polyclonal antibody raised against apoE isolated from hepatogeneous very low density lipoproteins (VLDL). The distribution of this antibody was visualized with colloidal gold complexed to anti-rabbit IgG. By epipolarization microscopy, apoE was found uniformly along the basolateral surfaces of all hepatic parenchymal cells, showing a striking intensity along the sinusoidal front. Punctate deposits of colloidal gold appeared to be randomly distributed within all hepatocytes. Widely scattered Kupffer cells also stained for apoE. Electron microscopic examination of immunogold-labeled cryothin sections showed that hepatocytic microvilli projecting into the space of Disse consistently contained clusters of immunogold. The gold particles were variably associated with evident lipoprotein particles, raising the possibility that apoE alone may bind to receptors or other macromolecules at the surface of hepatocytes. Endosomes near the sinusoidal front and multivesicular bodies in the Golgi/biliary area labeled intensely for apoE, consistent with a high content of apoE associated with triglyceride-rich lipoprotein remnants contained within these organelles. Some but not all nascent VLDL particles within putative forming Golgi secretory vesicles were labeled, but many other Golgi vesicles and cisternae that lacked evident VLDL particles were also labeled. These results suggest that at least some apoE associates with nascent VLDL in forming Golgi secretory vesicles. Unexpectedly, the matrix of all hepatocytic peroxisomes was heavily labeled. Immunoblots with the affinity-purified anti-rat apoE IgG against proteins from highly purified peroxisomes isolated from rat hepatocytes revealed a protein with an apparent molecular mass of 34.5 kDa, similar to that of rat apoE in rat blood plasma. In addition, gold was sometimes found in the area either adjacent to peroxisomes or between multivesicular bodies and the bile canaliculus not evidently associated with a membranous compartment. These observations suggest that apoE may participate in interorganellar cholesterol transport within hepatocytes.     

Purification of the microsomal Ca2+-ATPase from rat liver

Summary The Ca²⁺-ATPase from rat liver microsomes has been solubilized in Triton X-100 and purified to homogeneity by ficollsucrose treatment, column chromatography with agarose-hexane adenosine 5-triphosphate Type 2, and high pressure liquid chromatography (HPLC). The purified enzyme obtained by this sequential procedure exhibited a 183-fold increase in specific activity. After ficoll-sucrose treatment, the activity of the Ca²⁺-ATPase was stable for at least two weeks when stored at –70°C. In SDS-polyacrylamide gels, several fractions from HPLC chromatography showed a single band at a position corresponding to a molecular weight of about 107 kDa. This value is consistent with the molecular weight of the phosphoenzyme intermediate of endoplasmic reticulum (ER) Ca²⁺-ATPase. Further characterization of the ER Ca²⁺-ATPase was performed by western immunoblots. Antiserum raised against the 100-kDa sarcoplasmic reticulum (SR) Ca²⁺-ATPase cross-reacted with the purified Ca²⁺-ATPase from rat liver ER membranes.     

The biological effect of sodium butyrate (NaBT) on SGC-7901 cells

Changes of (Na+-K+)-ATPase activity, cAMP and fibronectin (FN) content and cell surface microvilli were studied cytochemically, immunocytochemically and scanning electron microscopically on human stomach Glandular carcinoma (SGC-7901) cells treated with NaBT(2.5 mM). It was found that NaBT not only inhibited cell growth but also remarkably decreased the activity of cell surface (Na+-K+)-ATPase of SGC-7901 cells. Note worthy was that, in comparison with the untreated tumor cells, the increase of the intensity of intracellular cAMP and FN immunofluorescence in NaBT-treated tumor cells was striking. Moreover, in contrast to untreated tumor cells, the cell surface of NaBT-treated tumor cells showed more smooth and fewer microvilli under SEM. That NaBT may induce differentiation of SGC-7901 cells through inhibition of (Na+-K+)-ATPase activity and modulation of cellular cAMP and FN content was discussed.     

Nucleotide sequence and analysis of the N-terminal coding region of the Spodoptera-activeδ-endotoxin gene of Bacillus thuringiensis aizawai 7.29

The nucleotide sequence of a 2711bp DNA segment which contains the N-terminal coding sequence and the 5' flanking region of a crystal protein gene (bta) from Bacillus thuringiensis subsp. aizawai 7.29 has been determined. The coding region encodes an 824 amino-acid polypeptide corresponding to a carboxy-terminally truncated delta-endotoxin specifically active against the cotton leaf worm Spodoptera littoralis. Comparison of the deduced amino acid sequence of the bta gene with that of the 4.5, 5.3 and 6.6 kb classes of lepidopteran-active delta-endotoxins revealed that the Bta sequence contains a very high level of amino acid substitutions in the N-terminal part of the protoxin molecule. The substitutions are grouped in several highly variable segments separated by highly conserved regions. These conserved domains are also present in the dipteran- and coleopteran-active delta-endotoxins. The control region of the bta gene shows considerable DNA identity with the control regions of the other lepidopteran-active genes. Deletions of the 3' region of the gene were carried out and the toxic fraction of the bta delta-endotoxin was identified with the N-terminal half of the molecule.