PBK/TOPK promotes chemoresistance to oxaliplatin in hepatocellular carcinoma cells by regulating PTEN

Oxaliplatin(OXA)resistance limits the efficiency of treatment for hepatocellular carcinoma(HCC).Studies have shown that the PDZ-binding kinase(PBK)plays importa...     

草莓离体无性繁殖的研究——Ⅰ.影响草莓离体繁殖的因素

基本培养基对草莓的离体快速繁殖有重要影响。通过试验筛选出一个比目前常用的MS和White培养基分别高5.53倍和2.3倍的F培养基(总氮量15mM,其中硝态氮10mM,铵态氮5mM,其它成份同MS)。相同浓度的BA与不同的基本培养基配合作用效果相差悬殊。由于草莓茎尖在MS培养基上生长缓慢,本文探讨了在室温条件下进行草莓种质保存的可能性。还讨论了由花药培养获得再生植株在快速繁殖中的应用问题。     

哑特猕猴桃微繁工艺流程的研究

选用哑特猕猴桃腋芽为外植体。在不同发育阶段适宜培养基组成：芽增殖生长培养基为ＭＳ＋６－ＢＡ０．５ｍｇ／Ｌ＋ＩＡＡ０．１ｍｇ／Ｌ（或者ＩＢＡ０．１ｍｇ／Ｌ;ＮＡＡ０．１ｍｇ／Ｌ）,其在苗基部呈辐射状萌发多个嫩枝与主茎伸长生长同步进行的繁殖特点,有利提高繁殖率。４０ｄ繁殖系数为５－７。诱导生根培养基为ＭＳ＋ＩＢＡ０．５ｍｇ／Ｌ＋ＩＡＡ０．２ｍｇ／Ｌ,生根率达９７．１％,培养３０ｄ,平均苗高３．５ｃｍ,     

Crystal structure of pokeweed antiviral protein from seeds of Phytolacca americana at 0.25 nm

ＡｔｖａｒｉｏｕｓｄｅｖｅｌｏｐｉｎｇｓｔａｇｅｓｔｈｅｄｉｆｆｅｒｅｎｔｔｉｓｓｕｅｓｏｆＰ.ａｍｅｒｉｃａｎａ(ｐｏｋｅｗｅｅｄ)ｃａｎｓｙｎｔｈｅｓｉｚｅａｃｌａｓｓｏｆｉｓｏｚｙｍｅｓｗｉｔｈｔｈｅａｂｉｌｉｔｙｔｏｉｎｈｉｂｉｔｔｈｅｐｒｏｌｉｆｅｒａｔｉｏｎｏｆｖｉｒｕｓ.ＴｈｉｓａｂｉｌｉｔｙｌｅａｄｓｔｏｔｈｅｄｉｓｃｏｖｅｒｙａｎｄｎａｍｅｏｆＰＡＰｓ[1—4].ＤｉｆｆｅｒｅｎｔＰＡＰｓｈａｖｅｂｅｅｎｆｏｕｎｄｆｒｏｍｌｅａｖｅｓ(ＰＡＰ)[1],ｓｕｍｍｅｒｌｅａｖｅｓ(ＰＡＰＩＩ)[2],…     

水溶性羧甲基茯苓次聚糖的合成及性能研究

羧甲基茯苓次聚糖具有明显的抗肿瘤活性,有希望作为优良的细胞药物响应的免疫促进剂。本文研究了水溶性羧甲基茯苓次聚糖的合成工艺,确定了β-茯苓次聚糖羧甲基化条件.并用IR、~(13)C NMR对化合物进行了结构表征。     

An unusual allosteric mobility of the C-terminal helix of a high-affinity alphaL integrin I domain variant bound to ICAM-5

Integrins are cell surface receptors that transduce signals bidirectionally across the plasma membrane. The key event of integrin signaling is the allosteric regulation between its ligand-binding site and the C-terminal helix (alpha7) of integrin's inserted (I) domain. A significant axial movement of the alpha7 helix is associated with the open, active conformation of integrins. We describe the crystal structure of an engineered high-affinity I domain from the integrin alpha(L)beta(2) (LFA-1) alpha subunit in complex with the N-terminal two domains of ICAM-5, an adhesion molecule expressed in telencephalic neurons. The finding that the alpha7 helix swings out and inserts into a neighboring I domain in an upside-down orientation in the crystals implies an intrinsically unusual mobility of this helix. This remarkable feature allows the alpha7 helix to trigger integrin's large-scale conformational changes with little energy penalty. It serves as a mechanistic example of how a weakly bound adhesion molecule works in signaling.     

Conservation of nonpeptide antigen recognition by rhesus monkey V gamma 2V delta 2 T cells

We have previously found that monkey Vgamma2Vdelta2(+) T cells mount adaptive immune responses in response to Mycobacterium bovis bacillus Calmette-Guérin infections. We have now analyzed rhesus monkey gammadelta T cell responses to nonpeptide Ags and superantigens. Like human Vgamma2Vdelta2(+) T cells, rhesus monkey gammadelta T cells are stimulated when exposed to prenyl pyrophosphate, bisphosphonate, and alkylamine Ags. Responsiveness was limited to gammadelta T cells expressing Vgamma2Vdelta2 TCRs. Rhesus monkey Vgamma2Vdelta2(+) T cells also responded to the superantigen, staphyloccocal enterotoxin A. Sequencing of the rhesus monkey Vgamma2Vdelta2 TCR revealed a strong sequence homology to human Vgamma2Vdelta2 TCR that preserves important sequence motifs. Moreover, chimeric TCRs that pair human Vgamma2 with monkey Vdelta2 and monkey Vgamma2 with human Vdelta2 retain reactivity to nonpeptide Ags and B cell lymphomas. A molecular model of the rhesus monkey Vgamma2Vdelta2 TCR has a basic region in the complementarity-determining region 3 binding groove that is similar to that seen in the human Vgamma2Vdelta2 TCR and preserves the topology of the complementarity-determining region loops. Thus, recognition of nonpeptide prenyl pyrophosphate, bisphosphonate, and alkylamine Ags is conserved in primates suggesting that primates can provide an animal model for human gammadelta T cell Ag responses.     

Type XIII collagen and some other transmembrane collagens contain two separate coiled-coil motifs,which may function as independent oligomerization domains

Type XIII collagen is a homotrimeric transmembrane collagen composed of a short intracellular domain, a single membrane-spanning region, and an extracellular ectodomain with three collagenous domains (COL1-3) separated by short non-collagenous domains (NC1-4). Several collagenous transmembrane proteins have been found to harbor a conserved sequence next to their membrane-spanning regions, and in the case of type XIII collagen this sequence has been demonstrated to be important for chain association. We show here that this 21-residue sequence is necessary but not sufficient for NC1 association. Furthermore, the NC1 association region was predicted to form an alpha-helical coiled-coil structure, which may already begin at the membrane-spanning region, as is also predicted for the related collagen types XXIII and XXV. Interestingly, a second coiled-coil structure is predicted to be located in the NC3 domain of type XIII collagen and in the corresponding domains of types XXIII and XXV. It is found experimentally that the absence of the NC1 coiled-coil domain leads to a lack of disulfide-bonded trimers and misfolding of the membrane-proximal collagenous domain COL1, whereas the COL2 and COL3 domains are correctly folded. We suggest that the NC1 coiled-coil domain is important for association of the N-terminal part of the type XIII collagen alpha chains, whereas the NC3 coiled-coil domain is implicated in the association of the C-terminal part of the molecule. All in all, we propose that two widely separated coiled-coil domains of type XIII and related collagens function as independent oligomerization domains participating in the folding of distinct areas of the molecule.     

Analysis of Chlamydomonas reinhardtii genome structure using large-scale sequencing of regions on linkage groups I and III

Chlamydomonas reinhardtii is a unicellular green alga that has been used as a model organism for the study of flagella and basal bodies as well as photosynthesis. This report analyzes finished genomic DNA sequence for 0.5% of the nuclear genome. We have used three gene prediction programs as well as EST and protein homology data to estimate the total number of genes in Chlamydomonas to be between 12,000 and 16,400. Chlamydomonas appears to have many more genes than any other unicellular organism sequenced to date. Twenty-seven percent of the predicted genes have significant identity to both ESTs and to known proteins in other organisms, 32% of the predicted genes have significant identity to ESTs alone, and 14% have significant similarity to known proteins in other organisms. For gene prediction in Chlamydomonas, GreenGenie appeared to have the highest sensitivity and specificity at the exon level, scoring 71% and 82%. respectively. Two new alternative splicing events were predicted by aligning Chlamydomonas ESTs to the genomic sequence. Finally recombination differs between the two sequenced contigs. The 350-Kb of the Linkage group III contig is devoid of recombination, while the Linkage group I contig is 30 map units long over 33-kb.