Characteristics of Modified Leghemoglobins Isolated from Soybean (Glycine max Merr.) Root Nodules

Hemoprotein derivatives of an abundant soybean (Glycine max Merr.) root nodule leghemoglobin, Lba, were studied for their modified spectral characteristics and physical properties. Three modified hemoprotein derivatives of Lba (Lbam1, Lbam2, and Lbam3) were purified by preparative isoelectric focusing. The ferric forms of these pigments were green and exhibited anomalous spectra in the visible region as compared to the Lba3+ forms. These modified pigments showed a hypochromic shift of 10 nm for the charge transfer absorption maximum; however, differences were not apparent in the Soret region. Upon binding with nicotinate, the [alpha] and [beta] bands were shifted significantly into the red region as compared to the Lba3+ nicotinate complex. The three Lbam fractions were reduced by dithionite or by NADH in the presence of riboflavin. Lbam2+ also bound nicotinate and displayed absorption spectra indistinguishable from those of Lba2+ nicotinate. In contrast to Lba2+, Lbam2+ displayed aberrant spectra when bound with either O2 or CO. These complexes exhibited a prominent charge transfer band at approximately 620 nm and failed to exhibit spectra characteristic of Lba2+O2 and Lba2+CO. The protein moiety of these modified pigments was intact because their tyrosine/tryptophan ratios and their amino acid compositions were identical with those of Lba, nor were differences observed in the peptide profiles resulting from trypsin digests of purified Lba and Lbams. Automated Edman degradation of selected peaks further confirmed the intactness of the protein backbone including the absence of deamination. Pyridine hemochromogen for heme from Lbams could be formed, and the spectra displayed distinct differences compared to those of Lba. A new peak at 580 nm and a loss of a peak at 480 nm were observed for all three Lbams.     

中国盲走螨属一新种和二新纪录：蜱螨亚纲：植绥螨科

本文记述我国植绥螨科盲走螨属Ｔｙｐｈｌｏｄｒｏｍｕｓ一新种和中国二新纪录：鲁盲走螨Ｔ．ｌｕｅｎｓｉｓ ｓｐ．ｎｏｖ．,甲胄盲走螨Ｔ．ｌｏｒｃａｔｕｓ,肥厚盲走螨Ｔ．ｈｉｇｏｅｎｓｉｓ。标本保存于上海复旦大学环境和资源生物系。     

Mathematical models for the swimming pattern of a lamprey

A significant characteristic in a swimming pattern of a lamprey is the generation of a constant phase lag along its body in spite of the wide range of undulation frequencies. In this paper, we discuss a mathematical treatment for coupled oscillators with time-delayed interaction and propose a model for the central pattern generator (CPG) of a lamprey to account for the generation of a constant phase relation, with consideration of the signal conduction time. From this model, it is suggested that the desired phase relation can be produced by long ascending connections from the tail to the neck region of the CPG.     

Hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency: Identification of point mutations in Japanese patients with Lesch-Nyhan syndrome and hereditary gout and their permanent expression in an HPRT-deficient mouse cell line

Two different single nucleotide transitions of hypoxanthine-guanine phosphoribosyltransferase (HPRT) were identified in a Japanese patient with Lesch-Nyhan syndrome (LNS) and a patient with hereditary gout. HPRT enzyme activities in the two patients were severely deficient, but the size and amount of mRNA were normal according to Northern analysis. Entire coding regions of HPRT cDNAs were amplified by PCR and sequenced. A G-to-A substitution at base 208 in exon 3, which predicted glycine 70 to arginine, was detected in the LNS patient (identical mutation with HPRT_Utrecht). A C-to-A substitution at base 73 in exon 2, which predicted proline 25 to threonine, was detected in the gout patient (designated HPRT_Yonago). We transfected normal HPRT cDNA, mutant cDNA with HRPT_Utrecht or mutant cDNA with HPRT_Yonago, respectively, to HPRT-deficient mouse cells and isolated permanent expression cell lines. The HPRT-deficient mouse cells had no detectable HPRT activity and a very low amount of HPRT mRNA. When the HPRT-deficient mouse cells were transfected with normal human cDNA, HPRT enzyme activity increased to 21.8% that of normal mouse cells. The mouse cells transfected with HPRT_Utrecht showed no increase in HPRT activity; however, when the mouse cells were transfected with HPRT_Yonago, the activity increased to 2.4% that of normal activity. The proliferative phenotypes of these cells in HAT medium and in medium containing 6-thioguanine were similar to those of skin fibroblasts from the patients. This series of studies confirmed that each of the two point mutations was responsible for the decreases in HPRT enzyme activity, and the proliferative phenotypes in HAT medium and medium containing 6-thioguanine.     

黑龙江依兰早第三纪植物群的古气候分析

对黑龙江依兰煤矿煤层间的大量植物叶痕化石研究表明：依兰植物群有蕨类植物２ 种,裸子植物１０ 种,被子植物５８ 种,分属３４ 科４６属。植物群可分为两个植物组合：一个是下煤层上顶板的矿页岩层化石的组合,称Ａ 段组合,时代为早始新世。植物种类丰富,含有较多常绿阔叶成分,属北亚热带的常绿阔叶和落叶阔叶、针阔叶混生林。通过植物叶相特征分析,其全缘叶比例为３８％ 。用气候诺模图得出其古气候为年均温１３．２℃,年温差２０℃;另一个植物组合是煤系地层之上,即上煤层顶部的油页岩层中的Ｂ段化石组合,时代为早渐新世。植物以落叶成分为主,属暖温带落叶阔叶林和针阔叶混生林。全缘叶比例为３０％ 。古气候年均温为１１℃,年温差２５℃。表明植物区系组成完全不同,显示出气候随时代发生了演变,而使区系逐渐发展到今日的寒温带气候和植被     

向日葵幼苗环旋运动的三维轨迹

采用光学显微镜标尺和垂线原理制作的三维空间点测定仪,对向日葵（Ｈｅｌｉａｎｔｈｕｓ ａｎｎｕｕｓＬ．）幼苗的环旋运动进行了连续测量。结果表明：向日葵环旋运动的轨迹有椭圆型、摆动型和不规则型;同一植株在不同生长阶段所表现的环旋运动轨迹不一定相同,同一株龄的不同个体也不一定具有相同的运动轨迹;运动的方向有左旋和右旋,圆周运动光源可以显著地改变运动方向;从三维角度看,在整个下胚轴生长阶段,环旋运动的振幅存在一个由小变大再由大变小的变化规律     

非同位素PCR－单链构象多态性技术的建立和应用

ＰＣＲ－单链构象多态性技术问世以来,成为研究基因突变的工具,特别是在分子肿瘤学研究中,广泛应用于癌基因,抑癌基因突变的研究,常规ＰＣＲ－ＳＳＣＰ采用同位素标记ＰＣＲ产物,测序板电泳分离突变,在操作和费用上有种种局限,文章建立了一种非同位素ＰＣＲ－ＳＳＣＰ技术;通过不对称ＰＣＲ获得单链,普通ＰＡＧＥ分离,经银染检出突变,用这种方法,还研究了四株鼻咽癌细胞株ＣＮＥ１,ＣＮＥ２,ＨＫ１和ＳＵＮＥ１中肿瘤     

Increased shikonin production by hairy roots of Lithospermum erythrorhizon in two phase bubble column reactor

Summary Plant hairy root cultures of Lithospermum erythrorhizon were carried out to produce shikonin derivatives by employing in situ extraction with n-hexadecane in a shake flask and a bubble column bioreactor. Over 95 % shikonin produced was recovered in the n-hexadecane layer. In flask cultures the maximum concentration of shikonin with n-hexadecane extraction was 3 times higher than that obtained without extraction. In the two phase bubble column reactor, 572.6 mg/L of shikonin and 15.6 g/L of dry cell mass were obtained after 54 days. Shikonin was produced at a constant level of 10.6 mg/L day during this period.     

Mechanisms of TonB-catalyzed iron transport through the enteric bacterial cell envelope

The recent solution of enteric bacterial porin structure, and new insights into the mechanism by which outer membrane receptor proteins recognize and internalize specific ligands, advocates the re-evaluation of TonB-dependent transport physiology. In this minireview we discuss the potential structural features of siderophore receptors and TonB, and use this analysis to evaluate both existing and new models of energy and signal transduction from the inner membrane to the outer membrane of gram-negative bacteria.     

Interaction of the FAFB-containing subunit with the Photosystem 1 core heterodimer

The structure of the predicted amino acid sequence in the F_X domain of Photosystem 1 was studied by molecular modeling and a working hypothesis was developed for the functional interaction of PsaC with the core heterodimer. We propose that the intervening sequences between homologous cysteines in the F_X cluster form two flexible loops and participate in the binding of PsaC, and that the arginine residues in the two surface-exposed loops may promote the interaction between the P₇₀₀–F_X core and the subunit. The model was tested experimentally; chemical modification of arginine residues in the P₇₀₀–F_X core using phenylglyoxal prevented reconstitution of the core with PsaC and PsaD after insertion of FeS clusters in vitro. Treatment of the P₇₀₀–F_X core with trypsin also prevented reconstitution of terminal electron transfer to F_AF_B, although neither treatments affected the electron transfer to F_X as judged by flash kinetic spectrophotometry. Electron transfer in the P₇₀₀–F_AF_B complex was not impaired by either phenylglyoxal or trypsin treatment indicating that the small subunit(s) protect the arginine residues that become chemically modified or cleaved. The data are consistent with the working model and point to additional experiments designed to identify the specific residues involved in the interaction between the P₇₀₀–F_X core and PsaC.Abbreviations PG- phenylglyoxal - PS 1- Photosystem 1