东方法老蛛雌蛛的描述（蜘蛛目：跳蛛科）

报道采自甘肃文县的东方法老蛛雌蛛,为该种雌蛛的首次记述。     

屎克螂适宜的繁殖条件初步研究

１９９１—１９９４年对屎克螂适宜的繁殖条件研究结果：１．土层４０ｃｍ和６０ｃｍ的平均温度分别为１５．９２±６．３４℃和１５．８９±６．０８℃;平均土壤含水量分别为２６．７０±３．７４％和２３．７２±１．８８％,使各虫态处于一个几乎恒温恒湿的条件,有利于生长发育与越冬,２．土壤含水量１７％、２０％、２２％、２６％和２９％,其产卵最多的深度分别在６５─７０ｃｍ,７５─８０ｃｍ,６５─８０ｃｍ,６５—８０ｃｍ和３５—５０ｃｍ,分别占产卵总数的３４．１６％、４２．４２％、６８．４２％、５５．４０％和９０．５６％。３．不同土壤的产卵深度,沙壤土以土下４５—５０ｃｍ处最多,占产卵总数的３４．７８％;沙土以６５—８５ｃｍ最多,占产卵总数的８６．６７％;粘土以４５—６０ｃｍ最多,占产卵总数的５１．１１％。     

黑节草双受精过程及胚胎发育的研究

黑节草从传粉到受精约需１３０ｄ,精子在花粉管中形成,胚囊发育属蓼型胚囊,因反足细胞较早退化,故受精前胚囊多只由卵器和中央细胞组成。精卵核融合时,精核染色质进入卵核后凝集成颗粒状,并在原位与卵核的染色质融合,雌、雄性核仁一直维持至合子的第一次分裂期前。双受精作用正常,属于有丝分裂前配子融合类型,初生胚乳核发生２－３次分裂后逐渐退化消失,胚的发育局限于球形胚阶段。     

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。     

A double hairpin structure is necessary for the efficient encapsidation of spleen necrosis virus retroviral RNA.

We conducted a mutational analysis within the previously defined encapsidation sequence (E) for spleen necrosis virus (SNV), an avian retrovirus. We found that two regions are necessary for efficient SNV replication. The first region is a double hairpin structure as proposed by Konings et al. (1992, J. Virol., 66, 632-640); the second region is located downstream of the hairpins. We showed further that the double hairpin structure is required for efficient SNV RNA encapsidation. Our work is the first to demonstrate, via linker-scanning and site-directed mutagenesis, that a specific RNA secondary structure is required for the encapsidation of retroviral RNA. Analysis of a series of mutations within the E region indicates (i) that preserving the secondary structure of the two hairpins is important for efficient encapsidation and (ii) that the stem regions of the hairpins contain specific sequences critical for encapsidation. Within the hairpins, the presence of at least one of the two conserved GACG four-residue loops, but not the moderately conserved bulge sequence of the first hairpin, is crucial for function. The function of the hairpins is independent of the relative order of the two hairpins. However, the two hairpins are not redundant and are not functionally identical. Replacement of SNV double hairpin sequences with those of Moloney murine leukemia virus (M-MLV) has no detectable effect on the replication of SNV-based retrovirus vectors with reticuloendotheliosis virus strain A (REV-A) helper virus. Furthermore, replacement of the entire E sequence of SNV with that of Moloney murine sarcoma virus (M-MSV) and M-MLV results in retroviral vectors that replicate as well as SNV vectors with wild type SNV E. This result indicates that the encapsidation sequences of M-MSV/M-MLV and SNV are not virus specific and that, during packaging of SNV and MLV RNA with viral proteins from REV-A, the encapsidation sequences are recognized largely by their secondary or tertiary structures.     

Displacement of housekeeping proteasome subunits by MHC-encoded LMPs: a newly discovered mechanism for modulating the multicatalytic proteinase complex.

The degradation of cytoplasmic antigens to peptides presented by class I MHC molecules is thought to be mediated by the ubiquitin/proteasome pathway. Support for this view came from our observation that the subunit composition of proteasomes can be changed by interferon-gamma (IFN-gamma) treatment. Thereby two subunits, LMP2 and LMP7, which are encoded in the MHC class II region, are incorporated into the proteasomal complex, whereas other subunits disappear. In the experiments reported in this communication we studied the subunit changes occurring in cell lines where the expression of LMP2 or LMP7 can be regulated individually either by IFN-gamma induction or by applying a new system to control the expression of transfected LMPs. In both situations LMP2 induction leads exclusively to the disappearance of housekeeping subunit 2, whereas LMP7 affects only subunit 10. Subunit 2 was found to be 76% homologous to LMP2. Since incorporation of LMP2 into the proteasomal complex prevents processing of the subunit 2 precursor, we conclude that LMP2 displaces subunit 2 during assembly. Subunit displacement is most likely a general mechanism to modulate the catalytic activity of the proteasomal complex without changing its structure. Furthermore, the controlled incorporation of transfected subunits into the complex offers a new approach to study proteasome function in vivo.     

诺卡氏菌属GS-17耐热茁霉多糖酶的提纯和性质

诺卡氏菌属GS-17(Nocardia sp.GS-17)的耐热茁霉多糖酶(Pullulanase EC.3.2.1.41)的粗酶液经中空纤维柱超滤浓缩、羟基磷灰石柱层析和Pullulan-Sepharose 6B亲和层析,得到凝胶电泳均一的纯酶,比活提高264倍.酶作用最适温度为55℃,最适PH6.2,分子量140000,等电点pI为6.0.该酶水解茁霉多糖、支链淀粉和可溶性淀粉,但不水解糖原.酶在50℃作用于茁霉多糖的米氏常数K_m为0.90mg/ml,最大反应速度V_(max)为57μmol·min~(-1)·mg~(-1).Zn~(2 )、Fe~(3 )、Hg~(2 )、Cu~(2 )、Pb~(2 )和环状糊精对酶有抑制作用,Ca~(2 )对酶有激活作用.经蛋白质侧链化学修饰研究表明,色氨酸残基位于酶的活性位区.该酶是由1129个氨基酸残基组成的单肽链,酶的N末端序列经测定为:Ala-Gly-His-Gly-Pro-Asp-Val-Gln-Asp-Gly-     

Vibrational circular dichroism of A-, B-, and Z-form nucleic acids in the PO2-stretching region.

Vibrational circular dichroism (VCD) spectra were measured for H2O solutions of several natural and model DNAs (single and double strands, oligomers and polymers) in the B-form, poly(dG-dC)-poly(dG-dC) in the Z-form, and various duplex RNAs in an A-form over the PO2-stretching region. Only the symmetric PO2 stretch at approximately 1075 cm-1 yields a significant intensity VCD signal. Differences of the PO2-stretching VCD spectra found for these conformational types are consistent with the spectral changes seen in the base region, but no sequence dependence was seen in contrast to VCD for base modes. The B to Z transition is accompanied by an inversion of the PO2- VCD spectra, which is characteristic of the change in the helical sense of the nucleic acid backbone. A-RNAs give rise to the same sense of couplet VCD as do B-DNAs but have a somewhat different shape because of overlapping ribose modes. These PO2- VCD spectral characteristics have been successfully modeled using simple dipole coupling calculations. The invariability of the symmetric PO2- stretching mode VCD spectra to the base sequence as opposed to that found for the C = O stretching and base deformation modes is evidence that this mode will provide a stable indication of the DNA helical sense.     

Protein Kinase FA/Glycogen Synthase Kinase-3α After Heparin Potentiation Phosphorylates τ on Sites Abnormally Phosphorylated in Alzheimer''s Disease Brain

In this work, we tested the effect of ion channel blockers and of phorbol ester treatments on [³H]dopamine ([³H]DA) release and neurotensin (NT)-induced facilitation of [³H]DA release from cultures of rat fetal mesencephalic cells. The potassium channel blockers tetraethylammonium and 4-aminopyridine increased basal [³H]DA release and decreased K⁺-evoked [³H]DA release, whereas apamin was without effect. K⁺-evoked [³H]DA release was decreased by ω-conotoxin and nifedipine, totally suppressed by cadmium, and unaffected by amiloride. These results show the differential sensitivity of [³H]DA release to blockade of various ion channels and suggest the involvement of N-type, L-type, and non-L-non-N-type, but not T-type, voltage-sensitive calcium channels in K⁺-evoked release. Phorbol 12-myristate 13-acetate increased both spontaneous and K⁺-evoked [³H]DA release, suggesting a modulatory action of protein kinase C on DA release in this system. Unexpectedly, however, the effects of the phorbol ester were not counteracted by the protein kinase C inhibitors H7, staurosporine, or polymyxin B. NT-induced facilitation of K⁺-evoked [³H]DA release was insensitive to most of the ion channel blockers, except cadmium (64% decrease in NT effect), suggesting that the corresponding potassium' and calcium channels were not involved in the effect of NT on [³H]DA release in this system. The NT effect was totally suppressed by phorbol ester treatments, indicating a possible desensitization of the corresponding transduction mechanisms after protein kinase C activation.     

A proper transmembrane Ca2+ gradient is essential for the stimulation of adenylate cyclase activity by stimulatory GTP-binding protein

Stimulatory GTP-binding Protein (Gs) and adenylate cyclase prepared from bovine brain cortices were co-reconstituted into asolectin vesicles with or without 1000-fold transmembrane Ca²⁺ gradient. The results showed that both basal activity and Gs-stimulated activity of adenylate cyclase were highest in proteoliposomes with a transmembrane Ca²⁺ gradient similar to physiological condition (1 M Ca²⁺ outside and 1 mM Ca²⁺ inside) and lowest when the transmembrane Ca²⁺ gradient was in the inverse direction. Such a difference could be diminished following dissipation of the transmembrane Ca²⁺ gradient by A23187. Comparable conformational changes of Gs in proteoliposomes were also observed when Gs was labeled with the fluorescence probe, acrylodan. These results may indicate that a proper transmembrane Ca²⁺ gradient is essential not only for higher adenylate cyclase activity but also for its stimulation by Gs.