丹参等十一种中草药中微量元素的测定及其药效分析

近年来的研究发现,中草药中微量元素可能具有某些生理活性。为了探索微量元素与药效的关系,我们对十一种中草药,即丹参,太子参、淫羊藿、白芍药、狗脊、槟榔、茯苓、熟地黄、大黄、红花、黑附子,采用原子吸收分光光度法进行了铜、锌、锰、铁、镁、钙六种元素的含量测定,并对微量元素与疾病、药效的关系作了探讨。     

信阳茶园杂草群落及其消长规律的调查报告

本文首次系统地报导了信阳茶园杂草群落及其消长规律。几年来,先后调查了三十六个茶山和大小茶园,作样方139个,经整理有最常见的杂草群落23个,对其群落分布、外貌特征、盖度、消长规律做了详细的观察记载。     

测量荷电水雾水滴荷电量的实验研究

本文对测定荷电水雾水滴荷电量的两种新方法进行了实验研究。结果表明:方波交变电场法在技术上还需作进一步研究和改进;库仑计快速测定法不仅测定准确,且简单灵活、迅适方便,是测定荷电水雾水滴平均荷电量的一种切实可行的方法。     

Calcium/calmodulin-dependent protein kinase II increases glutamate and noradrenaline release from synaptosomes

A variety of evidence indicates that calcium-dependent protein phosphorylation modulates the release of neurotransmitter from nerve terminals. For instance, the injection of rat calcium/calmodulin-dependent protein kinase II (Ca2+/CaM-dependent PK II) into the preterminal digit of the squid giant synapse leads to an increase in the release of a so-far unidentified neurotransmitter induced by presynaptic depolarization. But until now, it has not been demonstrated that Ca2+/CaM-dependent PK II can also regulate neurotransmitter release in the vertebrate nervous system. Here we report that the introduction of Ca2+/CaM-dependent PK II, autoactivated by thiophosphorylation, into rat brain synaptosomes (isolated nerve terminals) increases the initial rate of induced release of two neurotransmitters, glutamate and noradrenaline. We also show that introduction of a selective peptidergic inhibitor of Ca2+/CaM-dependent PK II inhibits the initial rate of induced glutamate release. These results support the hypothesis that activation of Ca2+/CaM-dependent PK II in the nerve terminal removes a constraint on neurotransmitter release.     

A binding site for the T-cell co-receptor CD8 on the alpha 3 domain of HLA-A2

Adhesion measurements between CD8 and 48 point mutants of HLA-A2.1 show that the CD8 alpha-chain binds to the alpha 3 domain of HLA-A2.1. Three clusters of alpha 3 residues contribute to the binding, with an exposed, negatively charged loop (residues 223-229) playing a dominant role. CD8 binding correlates with cytotoxic T-cell recognition and sensitivity to inhibition by anti-CD8 antibodies. Impaired alloreactive T-cell recognition of an HLA-A2.1 mutant with reduced affinity for CD8 is not restored by functional CD8 binding sites on an antigenically irrelevant class I molecule. Therefore, complexes of CD8 and the T-cell receptor bound to the same class I major histocompatibility complex molecule seem to be necessary for T-cell activation.     

Genetic mapping of chronic childhood-onset spinal muscular atrophy to chromosome 5q11.2-13.3

SPINAL muscular atrophy (SMA) describes a group of heritable degenerative diseases that selectively affect the alpha-motor neuron. Childhood-onset SMAs rank second in frequency to cystic fibrosis among autosomal recessive disorders, and are the leading cause of heritable infant mortality. Predictions that genetic heterogeneity underlies the differences between types of SMA, together with the aggressive nature of the most-severe infantile form, make linkage analysis of SMA potentially complex. We have now analysed 13 clinically heterogeneous SMA families. We find that 'chronic' childhood-onset SMA (including intermediate SMA or SMA type II, and Kugelberg-Welander or SMA type III) is genetically homogeneous, mapping to chromosomal region 5q11.2-13.3.     

Retinal degeneration in the rd mouse is caused by a defect in the beta subunit of rod cGMP-phosphodiesterase

Mice homozygous for the rd mutation display hereditary retinal degeneration and the classic rd lines serve as a model for human retinitis pigmentosa. In affected animals the retinal rod photoreceptor cells begin degenerating at about postnatal day 8, and by four weeks no photoreceptors are left. Degeneration is preceded by accumulation of cyclic GMP in the retina and is correlated with deficient activity of the rod photoreceptor cGMP-phosphodiesterase. We have recently isolated a candidate complementary DNA for the rd gene from a mouse retinal library and completed the characterization of cDNAs encoding all subunits of bovine photoreceptor phosphodiesterase. The candidate cDNA shows strong homology with a cDNA encoding the bovine phosphodiesterase beta subunit. Here we present evidence that the candidate cDNA is the murine homologue of bovine phosphodiesterase beta cDNA. We conclude that the mouse rd locus encodes the rod photoreceptor cGMP-phosphodiesterase beta subunit.     

Triggering of cyclin degradation in interphase extracts of amphibian eggs by cdc2 kinase

The cell cycles of early Xenopus embryos consist of a rapid succession of alternating S and M phases. These cycles are controlled by the activity of a protein kinase complex (cdc2 kinase) which contains two subunits. One subunit is encoded by the frog homologue of the fission yeast cdc2+ gene, p34cdc2 and the other is a cyclin. The concentration of cyclins follows a sawtooth oscillation because they accumulate in interphase and are destroyed abruptly during mitosis. The association of cyclin and p34cdc2 is not sufficient for activation of cdc2 kinase, however; dephosphorylation of key tyrosine and threonine residues of p34cdc2 is necessary to turn on its kinase activity. The activity of cdc2 kinase is thus regulated by a combination of translational and post-translational mechanisms. The loss of cdc2 kinase activity at the end of mitosis depends on the destruction of the cyclin subunits. It has been suggested that this destruction is induced by cdc2 kinase itself, thereby providing a negative feedback loop to terminate mitosis. Here we report direct experimental evidence for this idea by showing that cyclin proteolysis can be triggered by adding cdc2 kinase to a cell-free extract of interphase Xenopus eggs.     

Detection and characterization of a folding intermediate in barnase by NMR

Protein engineering is being developed for mapping the energetics and pathway of protein folding. From kinetic studies on wild-type and mutant proteins, the sequence and energetics of formation of tertiary interactions of side chains can be mapped and the formation of secondary structure inferred. Here we cross-check and complement results from this approach by using a recently developed procedure that traps and characterizes secondary structure in intermediate states using 1H NMR. The refolding of barnase is shown to be a multiphasic process in which the secondary structure in alpha-helices and beta-sheets and some turns is formed more rapidly than is the overall folding.     

Molecular genetic basis of the histo-blood group ABO system

The histo-blood group ABO, the major human alloantigen system, involves three carbohydrate antigens (ABH). A, B and AB individuals express glycosyltransferase activities converting the H antigen into A or B antigens, whereas O(H) individuals lack such activity. Here we present a molecular basis for the ABO genotypes. The A and B genes differ in a few single-base substitutions, changing four amino-acid residues that may cause differences in A and B transferase specificity. A critical single-base deletion was found in the O gene, which results in an entirely different, inactive protein incapable of modifying the H antigen.