肝再生的调控及原癌基因表达

肝脏再生过程中受到多种体液因素的调控。肝细胞生长因子（ＨＧＦ）、肝刺激因子（ＨＳＳ）等对肝细胞有促分裂作用;转化生长因子β１（ＴＧＦβ１）等则具有抑制作用。此外,肝再生还需要去甲肾上腺素（ＮＥ）、胰岛素等辅助分裂原的存在,共同调节肝再生。肝细胞分裂增殖与原癌基因表达密切相关。肝细胞从静息期进入细胞周期,以及在整个细胞周期中,某些原癌基因有特征性的表达。     

Genetic diversity and its relationship to hybrid performance and heterosis in rice as revealed by PCR-based markers

Ten elite inbred lines (four japonica, six indica), chosen from those widely used in the hybrid rice breeding program at Human Hybrid Rice Research Center in China, were crossed to produce all possible hybrids excluding reciprocals. The 45 F₁ hybrids along with the ten parents were evaluated for eight traits of agronomic importance, including yield potential, in a replicated field trial. The ten parents were analyzed with 100 arbitrary decamer oligonucleotide primers and 22 microsatellite (simple sequence repeats, SSRs) primer sets via polymerase chain reaction (PCR). Out of the 100 random primers used, 74 were informative and amplified 202 non-redundant bands (variants) with a mean of 2.73 bands per polymorphic primer. All 22 microsatellite primer sets representing 23 loci in the rice genome showed polymorphisms among the ten parents and revealed 90 alleles with an average of 3.91 per SSR locus. Cluster analysis based on Nei's genetic distance calculated from the 291 (202 RAPDs, 89 SSRs) non-redundant variants separated the ten parental lines into two major groups that corresponds to indica and japonica subspecies, which is consistent with the pedigree information. Strong heterosis was observed in hybrids for most of the traits examined. For the 43 diallel crosses (excluding 2 crosses not heading), yield potential, its components (including panicles per plant, spikelets per panicle and 1000-grain weight) and their heterosis in F₁ hybrids showed a significant positive correlation with genetic distance. When separate analyses were performed for the three subsets, yield potential and its heterosis showed significant positive correlations with genetic distance for the 15 indica x indica crosses and the 6 japonica x japonica crosses; however, yield potential and its heterosis were not correlated with genetic distance for the 22 indica x japonica crosses. Results indicated that genetic distance measures based on RAPDs and SSRs may be useful for predicting yield potential and heterosis of intra-subspecific hybrids, but not inter-subspecies hybrids.     

Identification of QTLs affecting traits of agronomic importance in a recombinant inbred population derived from a subspecific rice cross

To detect QTLs controlling traits of agronomic importance in rice, two elite homozygous lines 9024 and LH422, which represent the indica and japonica subspecies of rice (Oryza sativa), were crossed. Subsequently a modified single-seed-descent procedure was employed to produce 194 recombinant inbred lines (F₈). The 194 lines were genotyped at 141 RFLP marker loci and evaluated in a field trial for 13 quantitative traits including grain yield. Transgressive segregants were observed for all traits examined. The number of significant QTLs (LOD 2.0) detected affecting each trait ranged from one to six. The percentage of phenotypic variance explained by each QTL ranged from 5.1% to 73.7%. For those traits for which two or more QTLs were detected, increases in the traits were conditioned by indica alleles at some QTLs Japonica alleles at others. No significant evidence was found for epistasis between markers associated with QTLs and all the other markers. Pleitropic effects of single QTLs on different traits are suggested by the observation of clustering of QTLs. No QTL for traits was found to map to the vicinity of major gene loci governing the same traits qualitatively. Evidence for putative orthologous QTLs across rice, maize, oat, and barley is discussed.     

Structure and dynamics of melittin in lysomyristoyl phosphatidylcholine micelles determined by nuclear magnetic resonance.

Mixed micelles of the 26-residue, lytic peptide melittin (MLT) and 1-myristoyl-2-hydroxyl-sn-glycero-3-phosphocholine (MMPC) in aqueous solution at 25 degrees C were investigated by (13)C- and (31)P-NMR spectroscopy. (13)C alpha chemical shifts of isotopically labeled synthetic MLT revealed that MLT in the micelle is predominantly alpha-helical and that the peptide secondary structure is stable from pH 4 to pH 11. Although the helical transformation of MLT as determined from NMR is evident at lipid:peptide molar ratios as low as 1:2, tryptophan fluorescence measurements demonstrate that well-defined micellar complexes do not predominate until lipid:peptide ratios exceed 30:1. (31)P linewidth measurements indicate that the interaction between phosphate ions in solution and cationic groups on MLT is pH dependent, and that the phosphoryl group of MMPC senses a constant charge, most likely +2, on MLT from pH 4 to pH 10. (13)C-NMR relaxation data, analyzed using the model-free formalism, show that the peptide backbone of MLT is partially, but not completely, immobilized in the mixed micelles. Specifically, order parameters (S(2)) of C alpha-H vectors averaged 0.7 and were somewhat larger for residues in the N-terminal half of the molecule. The amino terminal glycine had essentially the same range of motion as the backbone carbons. Likewise, order parameters for the trp side chain were similar to those found for the peptide C alpha moieties, as was verified by trp fluorescence anisotropy decay data. In contrast, the motion of the lysine side chains was less restricted, the average S(2) values for the C epsilon-H vectors being 0.19, 0.30, and 0.44 for lys-7, 21, and 23, respectively, for MLT in the mixed micelles. Values of the effective correlation time of the local motion tau e were in the motional narrowing limit and usually longer for side-chain atoms than for those in the backbone. The dynamics were independent of pH from pH 4 to pH 9, but at pH 11 the correlation time for the rotational motion of the mixed micelles as a whole increased from 10 ns to 16 ns, and S(2) for the lys side chains increased. Overall it appears that the MLT helix lies near the surface of the micelle at low to neutral pH, but at higher pH its orientation changes, accompanied by deeper penetration of the lysine side chains into the micelle interior. It is apparent, however, that the MLT-lipid interaction is not dependent on deprotonation of any of the titratable cationic groups in the peptide in the pH 4-10 range, and that there is substantial backbone and side-chain mobility in micelle-bound MLT.     

Phylogenetic relationship of medicinally importantCnidium officinale and Japanese Apiaceae based onrbcL sequences

Cnidium officinale Makino is important medicinally and economically, but its origin is uncertain. The phylogenetic relationship ofC. officinale is provided from the analyses based on the ribulose-1,5-bisphosphate carboxylase/oxgenase gene (rbcL) sequences of 41 species which represent the 34 genera of Aplaceae, the four genera of Araliaceae, and one genus each of Pittosporaceae, Cornaceae, and Caprifoliaceae. The strict consensus tree obtained supports a close relationship ofC. officinale to the Chinese members ofLigusticum, especially toL. chuanxiong. Additionally, the tree shows (1) polyphyly of the genusLigusticum and (2) monophyly of the subfamily Apioideae. Within Apioideae, we recognized some groups in our phylogenetic tree. The grouping is discordant in several respects with the traditional tribal divisions based mainly on fruit morphology.     

甜菜碱醛脱氢酶在菠菜叶细胞中的定位

将菠菜叶片匀浆后．用差速离心和梯度率心分离叶绿体、过氧物酶体、微粒体等细胞器和１０００００×ｇ上清法部分。用酶活测定法测定各部分甜菜碱醛脱氢酶（ＢＡＤＨ）的活性;用免疫扩散法鉴定各组分的ＢＡＤＨ。除叶绿体外,过氧物酶体、微粒体．以及１０００００×ｇ上清液中也存在ＢＡＤＨ。     

方差组分估计方法MIVQUE和REML的模拟比较

利用ＭｏｎｔｅＣａｒｌｏ方法,对４种数据结构进行了ＭＩＶＱＵＥ和ＲＥＭＬ两种方差组分估计方法的模拟比较。方差组分估计所用的模型为奶牛育种中常用的公畜模型,它包括场年季固定效应、公牛组固定效应和公牛随机效应。４种数据结构中最大的有１２８４７个观察值,场年季效应和公牛效应水平数分别为７７８和４７,它与北京市目前可利用的奶牛头胎产奶量记录资料相当。最小的数据结构只有２００个观察值,１４８个场年季和２０头公牛。比较指标为估计值的偏差和方差（理论的或根据１０００次重复模拟所得的经验值）。结果表明,对于较大样本的数据结构,两种方法差异很小,它们间的估计值的相关接近于１,偏差小于真值的１％,方差近似相等。对于较小样本的数据结构,ＭＩＶＱＵＥ则明显优于ＲＥＭＬ。本研究还表明,对于ＲＥＭＬ来说,类似数据结构１的样本已能满足其渐近无偏性和有效性的大样本特性。     

乙肝病毒PreSl片段与乙肝表面抗原羧端的融合表达

我们利用聚合酶链反应法（ＰＣＲ）得到了编码乙肝病毒肝细胞受体结合位点ＰｒｅＳｌ（２１￣４７）的基因片段,并将它分别融合到Ｓ基因中相应于第１７５,１８８和２２３位氨基酸残基处。所得到的融合基因插入痘苗病毒表达载体ｐＧＪＰ－５后,在哺乳动物细胞ＣＶ－１中进行了暂时表达,对融合蛋白的表达、分泌和抗原性的研究表明,３种融合基因均能表达具有Ｓ和ＰｒｅＳｌ双重抗原性的融合蛋白,但融合位点对表达水平和分泌性质有     

FIBONACCI级数与菊花结构规律的研究

本文论证了菲波纳斯（Fibonacci）级数与菊花花冠结构的关系,发现了花冠的通用数学模式：花冠（数目）＝（5×倍数）十F_n（F_(n－1)＋F_(n-2)）     

昆虫核酸分子系统学研究进展

本文从研究对象、方法、类群、内容等方面综述了近十年来昆虫核酸分子系统学研究进展概况。文中首先介绍了ＲＦＬＰＡ、探针杂交及ＤＮＡ指纹、ＰＣＲ与ＲＡＰＤ－ＰＣＲ、顺序分析方法及应用情况,列举了在双翅目、膜翅目、同翅目、直翅目等目昆虫中的研究进展,并从居群遗传结构、分类学研究、系统发育和分子进化４个方面总结了昆虫核酸分子系统学的研究内容和主要成果,最后指出ＲＡＰＤ－ＰＣＲ与ＲＦＬＰ联合用于测序是近期昆虫分子系统学上最有应用价值的方法。