中国无患子科的地理分布

无患子科是一个乏热带分布科,全世界有１４４属,１６８０种,本文着重阐述：１．无患子科的分类系统及演化;２．世界无患子科的地理分布;３．中国无患子科的地理分布;４．无患子科的早期化地点及散布途径。结果表明无患子科现代分布变异中心在亚洲（印度－马西亚）－非洲－南美洲。中国无患子科有２５属,５４种,特有成分外,均与印度一马来西亚共有,大多数位于分布区的边缘。根据化石记录及现代及分布推断,无患子科可能在白     

兼具SOD和GPX活力的双功能酶的制备及性质研究

用苯甲基磺酰氟（ＰＭＳＦ）和Ｈ_２Ｓｅ相继处理铜锌超氧化物岐化酶（Ｃｕ,Ｚｎ－ＳＯＤ）,将酶分子中的丝氨酸（Ｓｅｒ）转化为硒代半胱氨酸（ＳｅＣｙｓ）,从而引入了谷胱甘肽过氧化物酶（ＧＰＸ）的催化基团,使其在ＳＯＤ酶活性大部分保留的情况下,具有ＧＰＸ活性,其ＧＰＸ活力是ＰＺ５１活力的３０倍。研究了双功能酶的最佳制备条件,包括ＰＭＳＦ的剂量、反应最适温度及Ｈ_２Ｓｅ处理时间等,并用电子能谱、ＤＴＮＢ等方法测定了双功能酶的硒含量;测定了双功能酶对不同底物的米氏常数及双功能酶的荧光光谱、紫外吸收光谱及稳定性。     

Atomic composition of the hydrophobic and hydrophilic membrane sides of self-assembled SC3p hydrophobin.

The hydrophobin SC3p of Schizophyllum commune self-assembles into a 10-nm-thick amphipathic membrane at hydrophilic-hydrophobic interfaces. X-ray photoelectron spectroscopy of the hydrophobic membrane side of SC3p, assembled in vitro, showed an atomic composition similar to the calculated composition of SC3p when glycosylation was taken into account. The atomic composition measured at the hydrophilic membrane side deviated from that at the hydrophobic side and indicated the presence of a lower number of peptide bonds. High levels of S and N were detected only on mycelia carrying hydrophobic aerial hyphae, as expected with assembled SC3p present at the surface of these hyphae.     

Removal of Adsorbed Toxin Fragments That Modify Bacillus thuringiensis CryIC delta-Endotoxin Iodination and Binding by Sodium Dodecyl Sulfate Treatment and Renaturation

We report that 10- and 25-kDa toxin fragments adhere to CryIC prepared from Bacillus thuringiensis insecticidal crystals, block iodination, and alter membrane binding. There is no apparent affect on CryIC toxicity against Spodoptera exigua. Associated peptides remained bound to CryIC in the presence of 50 mM dithiothreitol or 6 M urea. A novel detergent-renaturation procedure was developed for the purification of B. thuringiensis CryIC toxin. Sodium dodecyl sulfate (SDS) treatment followed by gel filtration chromatography yielded a homogeneous 62-kDa CryIC toxin. After removal of SDS and renaturation, the purified CryIC toxin was fully insecticidal to S. exigua larvae. I-labeled CryIC bound with high affinity to brush border membrane vesicles from S. exigua larvae.     

Abscisic Acid-Induced Membrane Potential Changes in Barley Aleurone Protoplasts: a Possible Relevance for the Regulation of rab Gene Expression

The effect of ABA on the membrane potential of barley (Hordeumvulgare cv. Himalaya) aleurone protoplasts was studied by measuringthe distribution of the lipophilic cation tetraphenylphosphonium(TPP⁺). The resting membrane potential (E_m) according to ourmeasurements with TPP⁺ is about –53 mV and is in agreementwith membrane potential values as measured with intracellularmicroelectrodes (about –55 mV). The TPP⁺-measurementscould demonstrate a clear dependence of the resting E_m on theexternal pH (pH_e). Stimulation of the protoplasts with ABA induced a transienthyperpolarization of the membrane to –62 mV as measuredwith TPP⁺. The hyperpolarization was ABA-concentration dependent. Inhibition of the H⁺-ATPases with the specific proton pump inhibitorsdiethylstilbestrol (DES) or Micanozole effectively preventedhyperpolarization. This indicates that the hyperpolarizationis consistent with the activation of plasma membrane H⁺-ATPases.The K⁺-inward rectifier inhibitor BaCl₂ was able to prolongthe hyperpolarization. This result suggests that the hyperpolarizationcauses the opening of K⁺-channels. The ABA-induced proton-pump activation may be involved in ABA-inducedgene-expression, as DES was able to inhibit this gene expression.BaCl₂ did only show a slight inhibitory effect on ABA-inducedgene-expression. (Received January 4, 1994; Accepted April 12, 1994)     

Characterization of proteins by means of their buffer capacity, measured with an ISFET-based coulometric sensor—actuator system

Proteins form the specific selector in many biochemical sensors. A change in one of the properties of such a protein has to be detected by an appropriate transducer, which completes the biochemical sensor. One of these properties is the buffer capacity of a protein. If the binding of a substance to a protein can significantly change the proton binding, which accounts for the buffer capacity of proteins, the detection of this changed buffer capacity enables the construction of a new type of biosensor.

It will be shown that the buffer capacity can be measured with an ISFET-based sensor—actuator device. The alternating generation of protons and hydroxyl ions by alternating current coulometry at a porous noble metal actuator electrode causes an associated small pH perturbation, which is detected by the underlying pH-sensitive ISFET. The amplitude of the measured signal is a function of the buffer capacity of the solute, in which proteins can be present (or these proteins can be adsorbed in the porous actuator electrode of the device). A model describing the transfer function from the electrical input signal of the actuator to the resulting chemical output, which is subsequently detected by the ISFET pH sensor, is presented. Preliminary results of the measured buffer capacity of ribonuclease and lysozyme are presented.     

A simple procedure for the expression of genes in transgenic soybean callus tissue

Cotyledons from germinating seeds of the soybean cultivar Peking were inoculated with virulent Agrobacterium tumefaciens strain A281:pZA-7 which carries a wild type Ti plasmid pTiBo542 and a disarmed Ti plasmid (a binary vector)pZA-7 which contains the glucuronidase (uidA) and neomycin phosphotransferase (nptII) genes. Tumors were produced on all inoculated explants and 82% of these tumor lines were cotransformed by the nptII gene from the binary vector pZA-7 as shown by PCR analysis (18 of 22 lines tested). Eleven of these 18 lines were also resistant to kanamycin. Eleven lines expressed -glucuronidase activity (GUS), six of which were also kanamycin resistant. Since there is a high rate of coexpression of genes carried by the binary vector, this system provides a simple and rapid method for the expression of genes of interest in transformed soybean tissue which has been used successfully to test constructs designed for soybean transformation.     

Characterization of inhibitory effects of NH2OH and its N-methyl derivatives on the O2-evolving complex of Photosystem II

Inorganic cofactors (Mn, Ca²⁺ and Cl^-) are essential for oxidation of H₂O to O₂ by Photosystem II. The Mn reductants NH₂OH and its N-methyl derivatives have been employed as probes to further examine the interactions between these species and Mn at the active site of H₂O oxidation. Results of these studies show that the size of a hydroxylamine derivative regulates its ability to inactivate O₂ evolution activity, and that this size-dependent inhibition behavior arises from the protein structure of Photosystem II. A set of anions (Cl^-, F^- and SO₄ ^2-) is able to slow NH₂OH and CH₃NHOH inactivation of intact Photosystem II membranes by exerting a stabilizing influence on the extrinsic 23 and 17 kDa polypeptides. In contrast to this non-specific anion effect, only Cl^- is capable of attenuating CH₃NHOH and (CH₃)₂NOH inhibition in salt-washed preparations lacking the 23 and 17 kDa polypeptides. However, Cl^- fails to protect against NH₂OH inhibition in salt-washed membranes. These results indicate that the attack by NH₂OH and its N-methyl derivatives on Mn occurs at different sites in the O₂-evolving complex. The small reductant NH₂OH acts at a Cl^--insensitive site whereas the inhibitions by CH₃NHOH and (CH₃)₂NOH involve a site that is Cl^- sensitive. These findings are consistent with earlier studies showing that the size of primary amines controls the Cl^- sensitivity of their binding to Mn in the O₂-evolving complex.Abbreviation MES 4-morpholinoethanesulfonic acid - PS II Photosystem II     

A NEW EULOPHID PARASITIZING LITCHI GALL MIDGE FROM CHINA (HYMENOPTERA: CHALCIDOIDEA)

Abstract  Mangocharis litchii sp. nov. is described from south China as a parasitoid of Mayetiola sp. on leaf of litchi tree. The gall midge is a serious pest of the fruit tree in south China. The biology of the new chalcidoid is also dealt with. The genus Mangocharis is new to China.