Eviostachya hoegii Stockmans在中国五通组的首次发现

首次描述了Eviostachya hoegii Stockmans的营养部分,通过大量标本的观察,修订了前人有关其生殖部分和解剖部分的描述,并对其生殖部分进行了复原.同意Emberger(1968)的观点,将其归于Eviostachyrales中.     

福建永安丰海二叠系上部及三叠系底部的双壳类动物群*

系统研究了闽西永安丰海地区二叠系上部及三叠系下部的双壳类动物群面貌、层位及组合,并与国内外相当的地层进行了对比,阐明了该双壳动物群在二叠-三叠系界线划分中的地层意义.描述了15属24种(其中5新种)、5未定种.     

鄂东南地区下侏罗统武昌组的双壳类化石

湖北蒲圻车埠和大冶金山店下侏罗统武昌组的双壳类化石可划分为２个组合,武昌组中部Ｑｉｙａｎｇｉａ－Ａｐｓｅｕｄｏｃａｒｄｉｎｉａ组合和武昌组上部Ｈｕｂｅｒｉｃｏｎｃｈａ－Ｋｉｊａ（Ｗｕｃｈａｎｇｅｌｌａ）组合,前者时代为早侏罗世中晚期;后者暂归于早侏罗世最晚期。文中描述２新属１新亚属以及１５新种。     

A Continuous Fluorescence Assay of Renin Activity

A sensitive fluorescence assay that employs a new fluorogenic peptide substrate has been developed to continuously measure the proteolytic activity of human renin. The substrate, DABCYL-gaba-Ile-His-Pro-Phe-His-Leu-Val-Ile-His-Thr-EDANS, has been designed to incorporate the renin cleavage site that occurs in the N-terminal peptide of human angiotensinogen. The assay relies upon resonance energy transfer-mediated, intramolecular fluorescence quenching that occurs in the intact peptide substrate. Efficient fluorescence quenching occurs as a result of favorable energetic overlap of the EDANS excited state and the DABCYL absorption, and the relatively long excited state lifetime of the EDANS fluorophore. Cleavage of the substrate by renin liberates the peptidyl-EDANS fragment from proximity with the DABCYL acceptor, restoring the higher, unattenuated fluorescence of the EDANS moiety. This leads to a time-dependent increase in fluorescence intensity, directly related to the extent of substrate consumed by renin cleavage. The kinetics of renin-catalyzed hydrolysis of this substrate have been shown to be consistent with a simple substrate inhibition model with a substrate K_m 1.5 μM at physiological pH; Cleavage of the substrate occurs specifically at the Leu-Val bond and corresponds to the renin cleavage site of angiotensinogen, as reported earlier. In this report, we describe in detail the synthesis of the fluorogenic renin substrate and its application in assays of renin activity. Assay sensitivity has been evaluated by a series of enzyme dilution experiments using the continuous assay format, showing that the assay can detect renin as low as 30 ng/ml after a incubation of only 3-5 min. It was estimated that with extended incubation time (2-3 h) the assay can detect renin at 0.5 ng/ml concentration level. An automated, high throughput fluorometric renin assay has been developed for a 96-well microtiter-plate fluorescence reader, which is useful for studies of enzyme inhibitors and enzyme stability.     

In situ fermentation monitoring with recombinant firefly luciferase

A novel method is described for the on-line determination of viable cell number. It has been tested in fermentations of Escherichia coli. The cells are transfected with the gene for firefly luciferase and fed low levels of luciferin in the medium. The reaction requires ATP, so the nonviable cells cannot produce light. Thus, light production is linear with viable cell density from innoculation through most of exponential growth. The light emitted by these cells is then conducted from the reaction vessel to the light detection equipment by an optical fiber. With the equipment described below, as few as a 10(6) cells/mL, or an OD(600) of 0.004, are easily detectable and concentrations greater than 10(10) cells/mL are well within range. The data are collected by a computer, so adaptation to on-line control applications is straightforward. During lag phase, this method is much more accurate then optical density measurements. At the end of exponential growth, rapid changes in light production mark carbon source depletion and the onset of cell lysis. A simple model accounts for the luciferin used during the fermentation and corrects the light detected to the proper cell density. (c) 1993 John Wiley & Sons, Inc.     

Modulation of SPARC Expression during Butyrate-Induced Terminal Differentiation of Cultured Human Keratinocytes: Regulation via a TGF-β-Dependent Pathway

Expression of SPARC (secreted protein acidic and rich in cysteine), a 43-kDa extracellular matrix-associated glycoprotein involved in tissue remodeling, was quantitated during normal human keratinocyte (NHK) growth in culture and as a function of sodium n-butyrate (NaB)-induced differentiation to mature enucleate cornified envelopes (CEs). Low levels of SPARC expression were observed in the basal-like cells of control NHKs, with isolated cells showing intense SPARC expression on the ventral surface. After addition of NaB, SPARC expression increased and the pattern of expression shifted to one involving predominantly suprabasal cells (i.e., spinous cells, pre-CEs, and mature CEs). Dense deposits of SPARC often surrounded the mature CEs. Flow cytometric analysis indicated that approximately 13% of NHKs expressed SPARC within 24 h of seeding into culture. This fraction of SPARC⁺ cells increased with time and peaked immediately postconfluence (31.3 ± 6.3% SPARC⁺). Cellular SPARC expression then decreased to baseline levels during entrance into plateau phase growth. SPARC was detectable in all phases of the cell cycle. SPARC levels were more intense and heterogeneous within the G₂/M and G₁ phases while S phase cells exhibited relatively homogeneous, low intensity, SPARC expression. During NaB-induced NHK differentiation, SPARC intracellular content increased prior to the onset of CE formation (i.e., 2 days after its addition) followed by a period of extracellular accumulation which coincided with the time of maximal CE generation (i.e., Days 4 and 5 after NaB addition). Correlation of cell size with anti-SPARC immunoreactivity revealed a predominance of SPARC expression in cells with a suprabasal phenotype. NHKs cultured on fibronectin (FN), an established modulator of epidermal cell maturation in vitro, showed a similar response to NaB. In general, however, the level of NaB-induced SPARC expression was considerably reduced in FN cultures correlating with a lower efficiency of CE formation. Induced SPARC expression was, in large part, dependent on autocrine transforming growth factor-β (TGF-β) production since incubation in the presence of NaB + neutralizing antibodies to TGF-β inhibited both the expression of SPARC by 72% and development of mature CEs.     

Growth characteristics of the diatoms Pseudonitzschia pungens and P. fraudulenta exposed to ultraviolet radiation

Interest in the biology of planktonic, chain-forming Pseudonitzschia species has grown recently after the discovery of toxin production in Pseudonitzschia pungens and related taxa, following the outbreak of shellfish toxicity in Canada in 1987. As part of a broader study on the effects of enhanced ultraviolet light on the growth of bloom-forming phytoplankton, we have examined the growth rates and production of the toxin domoic acid and two additional chemicals [bacillariolides I and II] by Pseudonitzschia pungens varieties and Pseudonitzschia fraudulenta from Narragansett Bay, Rhode Island. Growth of P. fraudulenta is significantly inhibited by enhanced UV, P. pungens var. pungens shows slight inhibition, and P. pungens var. multiseries is unaffected. Production of bacillariolides I and II by P. pungens var. multiseries is similar in enhanced and deleted UV light. Tolerance of UV light by P. pungens var. multiseries appears to be acquired, and persistent. If ambient UV light continues to increase as a result of global ozone depletion, one may expect UV-resistant taxa such as P. pungens var. multiseries to become more prominent in coastal phytoplankton communities.     

Purification and characterization of bovine brain calmodulin-dependent protein kinase II. The significance of autophosphorylation in the regulation of 63 kDa calmodulin-dependent cyclic nucleotide phosphodiesterase isozyme

Bovine brain contains two calmodulin-dependent phosphodiesterase kinases which are separated on Sephacryl S-300 column. One of these kinases has been purified to homogeneity and shown to belong to the calmodulin-dependent protein kinase II family. Phosphorylation of the 63 kDa phosphodiesterase by this purified protein kinase results in the incorporation of 1.0 mol phosphate per mol subunit and an accompanying increase in Ca²⁺ concentrations required for the phosphodiesterase activation by calmodulin. The protein kinase undergoes autophosphorylation to incorporate 1.0 mol phosphate per mol of subunit of the enzyme and the autophosphorylated enzyme is active, independent of the presence of Ca²⁺. The autophosphorylation reaction as well as the protein kinase reaction are rendered Ca²⁺ independent in less than 15 seconds when approximately one mol phosphate per mol protein kinase is incorporated. The result suggests that activation of phosphodiesterase phosphorylation reaction may occur prior to the activation of phosphodiesterase and phosphatase during a cell Ca²⁺ flux via the protein kinase autophosphorylation mechanism.Abbreviations SDS sodium dodecyl sulfate - EGTA ethylene glycol bis (-aminoethyl ether) - N,N,N,N tetra acetic acid - EDTA ethylenediamine-tetraacetic acid - cAMP cyclic adenosine 35 monophosphate This work is supported by grants from the Medical Research Council of Canada (JHW), the Heart and Stroke Foundation of Alberta (JHW and RKS) and the Heart and Stroke Foundation of Saskatchewan (RKS)