Extreme diversity, conservation, and convergence of spider silk fibroin sequences

Spiders (Araneae) spin high-performance silks from liquid fibroin proteins. Fibroin sequences from basal spider lineages reveal mosaics of amino acid motifs that differ radically from previously described spider silk sequences. The silk fibers of Araneae are constructed from many protein designs. Yet, the repetitive sequences of fibroins from orb-weaving spiders have been maintained, presumably by stabilizing selection, over 125 million years of evolutionary history. The retention of these conserved motifs since the Mesozoic and their convergent evolution in other structural superproteins imply that these sequences are central to understanding the exceptional mechanical properties of orb weaver silks.     

利用复合酶改善烟梗品质的研究

[目的]利用复合酶改善烟梗内在品质,进一步提高梗丝在卷烟配方中的适用性。[方法]利用复合酶对烟梗的梗丝进行处理,催化降解其蛋白质、淀粉和纤维素,采用同时蒸馏法萃取梗丝中的中性香气成分,采用GC/MS进行香气分析,并对酶处理前后梗丝的中性香气物质进行比较和感官评吸鉴定。[结果]梗丝经复合酶处理后,总糖含量提高至22.8%,糖氮比和糖碱比均得到了提高;主要香气成分的总量提高了27%,其中美拉德反应产物含量提高了159%,类胡萝卜素降解产物含量提高了65.8%,并且大部分新植二烯降解为小分子香气物质,从而大大改善各种香气物质的含量和比例。[结论]感官评吸表明,经过复合酶处理,梗丝的香气品质得到了改善,感官总体质量有了较大提高。     

烟梗成丝的研究及应用

[目的]探索烟梗成丝的最佳工艺参数及其在制作高档烟中的应用。[方法]通过进行压梗、切梗厚度参数调整试验,寻求烟梗成丝效果较好的工艺参数,把成丝效果最好的梗丝按不同的比例搀兑到某牌号一类烟中进行卷制,然后对卷烟进行感官质量评价以及卷烟烟气的分析检测。[结果]烟梗的压梗厚度在0.8 mm,切梗厚度在0.10 mm时,烟梗成丝的效果较好;在高档烟中搀兑适当比例（≤15%）的丝状梗丝可提高卷烟香气的透发性,改善余味,降低卷烟的刺激性,提高卷烟的感官质量。但是过高的比例（〉15%）对卷烟感官质量有不利的影响;烟支的焦油含量、烟气烟碱量、CO量会随着丝状梗丝比例的增加而减小。[结论]该研究为提高梗丝的利用价值以及提高梗丝在高档烟中的使用比例提供了参考。     

超级纤维蜘蛛丝的研究进展

综述蜘蛛丝的生物合成、机械性能、蛋白质序列、生物物理研究、蛋白质结构和功能,以及丝蛋白基因工程的研究进展。     

蜘蛛丝蛋白基因的合成及其串联体在大肠杆菌中的表达

赋有许多独特性能的天然蛋白质纤维--蜘蛛丝在生物医学、材料和军事等领域具有广泛的应用前景，但惟有通过基因工程手段才能大量获取。根据已报道的蜘蛛丝蛋白的氨基酸序列，结合蜘蛛丝蛋白的模块结构特性和功能的关系，优化设计并人工合成了全长为429bp的蜘蛛丝蛋白基因SPS。将该基因克隆到质粒pET-32a中，构建成表达载体pET-SSPS1，并进一步构建了它的多个串联体表达载体pET-SPS（2～8）。所有表达载体在大肠杆菌BL21（DE3）中进行了诱导表达，重组蜘蛛丝蛋白得到了纯化。结果表明，合成的蜘蛛丝蛋白基因与预期一致，融合表达的蜘蛛丝蛋白几乎全部可溶。其中，1-3串联体蜘蛛丝蛋白基因能够有效表达，但随着串联数的进一步增加，蜘蛛丝蛋白基因融合表达效率下降，初步探讨了下降的可能原因。     

即食山竹笋玻璃罐头加工工艺研究

以当地山竹笋为主要原料,结合产区企业生产条件,研究了蒸汽常压杀菌排气、不同油封处理和笋丝褐变防控等生产工艺,获得了即食山竹笋玻璃罐头加工工艺技术;生产的产品笋丝呈淡黄色、笋肉脆嫩,符合国家相关产品质量卫生标准。     

棉铃虫取食玉米不同部位对其生长发育及繁殖的影响

在室内用玉米不同部位饲养棉铃虫,观察各部位对棉铃虫生长发育的影响。结果表明,除玉米心叶外,在其它各处理中,棉铃虫均可完成一个世代。以花丝为食料时,其存活率及产卵量为最高。     

家蚕平面丝均匀度的品种间差异

家蚕平面丝均匀度的优劣直接影响平面丝产品的质量．为探明家蚕品种间平面丝均匀度的遗传性差异，用单位面积丝重量的变异系数对菁松等１４个春用、夏秋用蚕品种以及薪杭×科明等８个一代杂交种吐成的平面丝的均匀度进行了研究．结果表明，平面丝均匀度在蚕品种间存在显著差异，一代杂交种的平面丝均匀度在不同的杂交组合及同一杂交组合的正反交之间均有差异，其遗传有母体影响较大的倾向     

家蚕脱胶蚕丝的蛋白组成成分

【目的】探讨家蚕（Bombyx mori）蚕丝纤维脱胶后蛋白质成分的变化,为了解丝蛋白在蚕丝纤维中的分布特征打下基础,并为改进蚕丝纤维加工工艺提供依据。【方法】利用木瓜蛋白酶、碳酸钠、尿素、中性皂和碱水法5种方法对蚕茧进行脱胶处理;并通过聚丙烯酰胺凝胶电泳检测不同方法处理的蚕丝和不同蚕丝加工产品的脱胶程度,以及脱胶对丝素的影响;利用FASP酶解法和液相色谱-串联质谱联用的技术鉴定不同方法脱胶后的蚕丝及各种蚕丝加工产品的蛋白组分;利用生物信息学的方法对鉴定到的丝蛋白进行注释并通过非标定量的方法比较各种样品中丝蛋白的丰度。【结果】通过5种方法对蚕茧丝进行脱胶,蛋白电泳检测发现木瓜蛋白酶法降解丝胶蛋白的同时基本不会破坏丝素蛋白;碳酸钠法对丝胶的降解能力较弱,但对丝素的降解较强;中性皂法和尿素法对丝胶蛋白和丝素蛋白的降解都比较严重;碱水法的效果不理想。通过蛋白质组学研究发现木瓜蛋白酶和中性皂法脱胶后的蚕丝中几乎没有丝胶蛋白,主要是丝素蛋白、seroin 1和甘氨酸富含蛋白等;尿素法和碳酸钠法脱胶后的蚕丝中残留蛋白最少,主要是丝素蛋白和甘氨酸富含蛋白等。通过蛋白电泳检测了6种蚕丝加工产品中的蛋白质,发现生丝和胚绸中的丝素蛋白比较完整,绸、缎和电力纺中的丝素蛋白出现了部分程度的降解,而丝绸旧衣中的丝素蛋白有严重的降解。通过蛋白质组学分析发现生丝和胚绸中的主要成分包括3种丝素、丝胶1、seroin 1、osiris 9a、甘氨酸富含蛋白和蛋白酶抑制剂SPI51等;绸、缎和电力纺的主要成分包括3种丝素蛋白和seroin 1,而丝绸旧衣中的主要成分包括3种丝素蛋白和甘氨酸富含蛋白。【结论】木瓜蛋白酶脱胶法能够最大程度地保持丝素纤维的完整性,碳酸钠和尿素法的脱胶程度最高。生丝和胚绸中的丝胶蛋白含量很高,丝素纤维比较完整。绸、缎和电力纺中的丝胶蛋白很少,丝素纤维有部分程度的降解。蚕丝经过彻底的脱胶后还剩余的蛋白包括丝素重链、丝素轻链、丝素p25、seroin 1和甘氨酸富含蛋白。     

家蚕糖转运蛋白BmST1基因的克隆与序列分析

糖转运蛋白运输葡萄糖、果糖、半乳糖、木糖等透过细胞膜为机体提供能量.根据GenBank已登陆的其他物种的糖转运蛋白序列与家蚕基因组框架图和EST序列获得家蚕同源糖转运蛋白基因BmST1.基因编码区长1 392 bp(GenBank登录号:FJ373021),编码463个氨基酸,预测蛋白分子质量为51.635 kDa.序列分析显示基因有2个外显子,含有11个跨膜结构域.RT-PCR表明该基因仅在此文所检测的家蚕丝腺中表达.     

The LDL receptor gene: a mosaic of exons shared with different proteins

The multifunctional nature of coated pit receptors predicts that these proteins will contain multiple domains. To establish the genetic basis for these domains (LDL) receptor. This gene is more than 45 kilobases in length and contains 18 exons, most of which correlate with functional domains previously defined at the protein level. Thirteen of the 18 exons encode protein sequences that are homologous to sequences in other proteins: five of these exons encode a sequence similar to one in the C9 component of complement; three exons encode a sequence similar to a repeat sequence in the precursor for epidermal growth factor (EGF) and in three proteins of the blood clotting system (factor IX, factor X, and protein C); and five other exons encode nonrepeated sequences that are shared only with the EGF precursor. The LDL receptor appears to be a mosaic protein built up of exons shared with different proteins, and it therefore belongs to several supergene families.     

蚕丝及Ⅱ型胶原凝胶支架负载软骨细胞构建组织工程类软骨

观察软骨细胞在蚕丝及胶原凝胶2种支架上生长状态,为软骨组织工程支架选择提供依据。将体外第2代兔关节软骨细胞接种于蚕丝和Ⅱ型胶原凝胶,倒置显微镜下观察软骨细胞在支架内的生长增殖状况,并对细胞-支架复合物进行组织切片观察。结果显示,经胶原包被后的蚕丝对软骨细胞表现出良好的吸附作用,并有利于软骨细胞的生长增殖。在培养初期,蚕丝内细胞生长增殖较胶原凝胶内的慢,但随后随着胶原支架的缀陵降解细胞增殖速度减慢,而蚕丝上的细胞数量仍在增加。该研究表明软骨细胞在蚕丝和胶原凝胶两种支架上都能维持正常生长状态,但蚕丝作戈、软骨组织工程支架在长期效果优于胶原凝胶。     

Effects of syncrhonization between silk receptivity and pollen grain vigor on kernel sets of corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

Kernel sets in corn were affected by silk receptivity, pollen grain vigor, and the synchronization of silking and pollen shedding. Grain yield decrement was often caused by poor kernel set ability under field conditions. This study was conducted with two corn hybrids—Yedan 12 and Yedan 19—in both field and laboratory to observe silk receptivity, pollen vigor, synchronization of silking and pollen, and their effects on the kernel sets. The results showed that silk receptivity could be maintained over a relatively longer period of time after silks emerged, but both kernel set percentage and kernel weight decreased as silks aged when pollination occurred. Pollen grains that shed earlier had higher TTC-dehydrogenase activity, higher germination percentage, more rapid pollen tube growth rate, and higher percentage of kernel sets and kernel weight than those that shed later. The effect of delayed silking on kernel set ability was more significant compared with delayed pollen. Synchronization of silking and pollen shedding showed different characters in different hybrids: “partial overlapped” for Yedan 12 and “overlapped” for Yedan 19.     

金纳米三角片对家蚕生长状况和蚕丝性质的影响研究

本研究通过足部注射的方式将金纳米三角片导入五龄家蚕幼虫的体内,通过研究家蚕的生长状况以及蚕丝性质的变化,对金纳米三角片的生物安全性进行了评估。结果显示,金纳米三角片的摄入大幅度降低了家蚕的成活率,存活下来的家蚕的平均体重、体长相比起空白对照组有所降低,但外貌无显著变化。X射线衍射（XRD）和红外（FTIR）结果表明,与空白组蚕丝相比,摄入金纳米三角片的实验组的蚕丝的晶体或二级结构并未遭到破坏。该研究为金纳米三角片的生物安全性提供了一定参考。     

Cassette of eight exons shared by genes for LDL receptor and EGF precursor

The amino acid sequences of the human low-density lipoprotein (LDL) receptor and the human precursor for epidermal growth factor (EGF) show 33 percent identity over a stretch of 400 residues. This region of homologous is encoded by eight contiguous exons in each respective gene. Of the nine introns that separate these exons, five are located in identical positions in the two protein sequences. This finding suggests that the homologous region may have resulted from a duplication of an ancestral gene and that the two genes evolved further by recruitment of exons from other genes, which provided the specific functional domains of the LDL receptor and the EGF precursor.     

How big is the universe of exons?

If genes have been assembled from exon subunits, the frequency with which exons are reused leads to an estimate of the size of the underlying exon universe. An exon database was constructed from available protein sequences, and homologous exons were identified on the basis of amino acid identity; statistically significant matches were determined by Monte Carlo methods. It is estimated that only 1000 to 7000 exons were needed to construct all proteins.     

Cloning One CIPK Gene from a Thermo-Sensitive Genic Self-Incompatible Line in Maize Expressing Under Different Temperatures

A calcineurin B-like protein-interacting protein kinases (CIPK) gene was cloned (EU 424058) from a thermo-sensitive genic self-incompatibility (TSGI) line, HE97, in maize, which was selected for suppression subtractive hybridization (SSH) library of the self-incompatible and self-compatible silks of the TSGI line under different temperatures. The full-length cDNA of the candidate CIPK-like gene consisted of 1 918 nucleotides and contained a 1 332-bp open reading frame in maize. Real-time PCR indicated that the candidate CIPK-like gene was highly expressed in the self-incompatible pollen of the TGSI line, and promoted elevated levels of calcium (Ca2+). High Ca2+ concentrations in the pollen strongly inhibit pollen tube formation in silk of the same plant, thus inducing self-incompatibility (SI) under high temperature. These results implied that the CIPKs-like gene would play an important role in the regulation of HE97 characteristics under different temperatures, perhaps acting as a secondary messenger in the expression of SI in the TGSI line in maize.     

Human-proto-oncogene nucleotide sequences corresponding to the transforming region of simian sarcoma virus

The nucleotide sequences of the six regions within the normal human cellular locus (c-sis) that correspond to the entire transforming region of the simian sarcoma virus (SSV) genome (v-sis) were determined. The regions are bounded by acceptor and donor splice sites and, except for region 6, resemble exons. Region 6 lacks a 3' donor splice site and terminates -5 base pairs from the 3' v-sis-helper-viral junction. This is consistent with a model proposing that SSV was generated by recombination between proviral DNA of a simian sarcoma associated virus and proto-sis and that introns were spliced out subsequently from a fused viral-sis messenger RNA. This also suggests that the 3' recombination occurred within an exon of the woolly monkey (Lagothrix) genome. The open reading frames predicting the v-sis and c-sis gene products coincide with the stop codon of c-sis located 123 nucleotides into the fifth region of homology. The overall nucleotide homology was 91 percent with substitutions mainly in the third codon positions within the open reading frame and with greatest divergence within the untranslated 3' portion of the sequences. The predicted protein products for v-sis and c-sis are 93 percent homologous. The predicted c-sis gene product is identical in 31 of 31 amino acids to one of the published sequences of platelet-derived growth factor. Thus, c-sis encodes one chain of human platelet-derived growth factor.     

小麦ADP-核糖基化因子克隆及序列分析

二磷酸腺苷-核糖基化作用因子(ADP-ribosylation factors,ARFs)是真核细胞囊泡运输通道的关键组成成分,参与细胞运输和信号传导。根据GenBank中已知ARF基因序列设计引物,对小麦及其二倍体供体种基因组DNA进行PCR扩增、克隆、测序。结果表明:从小麦中克隆的ARF基因属于ARF1基因;与其他物种的ARF基因对比发现,该基因的内含子存在特殊的剪切方式。氨基酸序列分析表明,小麦的ARF同其他物种一样,具有保守的GTP结合区域。     

Evidence of arrested silk growth in maize at high planting density using phenotypic and transcriptional analyses

Increasing the planting density is an effective way to increase the yield of maize(Zea mays L.), although it can also aggravate ovary apical abortion-induced bald tips of the ears, which might, in turn, reduce the yield. While the mechanism underlying the regulation of drought-related abortion in maize is well established,high planting density-related abortion in maize remains poorly understood. Therefore, the present study was designed to investigate the mechanism underlying the ovary apical ab...