Effects of vasoactive intestinal contractor (VIC) and endothelin on intracellular calcium level in neuroblastoma NG108-15 cells

Effects on [Ca2+]i levels of endothelin-l (ET) and vasoactive intestinal contractor peptide (VIC), which is a novel member of the endothelin family, were examined in fura 2-loaded neuroblastoma NG108-15 cells. VIC was found to be a very effective stimulus for intracellular Ca2+ mobilization and to be more potent than ET. Intracellular calcium response to sequential addition of two stimulants exhibited the homologous desensitization of either ET or VIC, but no heterologous desensitization between ET and VIC. This indicates evidence suggesting that these two peptides act through distinct receptors.     

Immunodetectable galactosyltransferase is associated only with human spermatozoa of high buoyant density

Human ejaculated spermatozoa are heterogeneous and can be separated into two distinct populations according to their respective buoyant densities. In order to investigate the functional differences between these two types of spermatozoa, we have searched for the presence of galactosyltransferase. A Western blot of sperm proteins following their electrophoresis was probed with an anti-galactosyltransferase serum revealing that this enzyme is present in human spermatozoa. Furthermore, galactosyltransferase is detectable only in those proteins isolated from the head of high density spermatozoa. These results suggest that ejaculated spermatozoa consist of two populations that are functionally different.     

Isoelectric focusing studies of bacteriorhodopsin

Purified bacteriorhodopsin (BR) samples show a minimum of four isoelectric forms in immobilized pH gradient isoelectric focusing gels. The bands occur as doublets with isoelectric points (pI) centered at 5.20 (principal species) and 5.60. In typical preparations additional bands may be observed at 4.90, 5.07 and 5.50. Purple membrane (PM) was proteolyzed with papain to calibrate the pI shift produced by changing the number of charges on the protein. Asp-242 is removed during the first cleavage between residues 239 and 240 resulting in the loss of a single negative charge and a shift of the principal doublet by +0.35 pH units to pI 5.55. The second papain cleavage occurs between residues 231 and 232 which removes Glu-232, -234 and -237 and shifts the pI by +0.60 pH units to pI 6.10. The +0.60 pH shift upon the second papain cleavage is consistent with the loss of two negative charges and is supported by prior evidence that at least one of the three glutamate residues lost during the second proteolysis step is protonated and neutral in the intact protein. The native and proteolyzed products of BR retain the characteristic 550 nm absorption maxima for solubilized BR. A model for the structural origin of the pI heterogeneity of BR species in proteolyzed PM is presented.     

nit-2, the major nitrogen regulatory gene of Neurospora crassa, encodes a protein with a putative zinc finger DNA-binding domain.

The nitrogen regulatory circuit of Neurospora crassa consists of a set of unlinked structural genes which specify various nitrogen catabolic enzymes plus control genes and metabolic effectors which regulate their expression. The positive-acting nit-2 regulatory gene is required to turn on the expression of the nitrogen catabolic enzymes during conditions of nitrogen limitation. The complete nucleotide sequence of the nit-2 gene was determined. The nit-2 mRNA is 4.3 kilobases long and has a long nontranslated sequence at both its 5' and 3' ends. The nit-2 gene nucleotide sequence can be translated to yield a protein containing 1,036 amino acid residues with a molecular weight of approximately 110,000. Deletion analyses demonstrated that approximately 21% of the NIT2 protein at its carboxy terminus can be removed without loss of function. The nit-2 protein contains a single putative Cys2/Cys2 zinc finger domain which appears to function in DNA binding and which has striking homology to a mammalian trans-acting factor, GF-1.     

Differentiation of embryonic chick sympathetic neurons in vivo: ultrastructure,and quantitative determinations of catecholamines and somatostatin

Summary The ultrastructural and transmitter development of lumbar sympathetic ganglia was studied in embryonic day-6 through-18 chick embryos. At embryonic day 6, ganglia are populated by two morphologically distinct types of neuronal cells and Schwann cell precursors. The neuronal populations basically comprise a granule-containing cell and a developing principal neuron. Granule-containing cells have, an irregularly shaped or oval nucleus with small clumps of chromatin attached to the inner nuclear membrane and numerous large (up to 300 nm) membrane-limited granules. Developing principal neurons display a more rounded vesicular nucleus with evenly distributed chromatin, prominent nucleoli, more developed areas of Golgi complexes, and rough endoplasmic reticulum and large dense-core vesicles up to 120 nm in diameter. There are granule-containing cells with fewer and smaller granules which still display the nucleus typical for granule-containing cells. These granule-containing cells may develop toward developing principal neurons or the resting state of granule-containing cells found in older ganglia. Both granule-containing cells and developing principal neurons proliferate and can undergo degeneration. At embryonic day 9 there are far more developing principal neurons than granule-containing cells. Most granule-containing cells have very few granules. Mitotic figures and signs of cell degeneration are still apparent. Synapse-like terminals are found on both developing principal neurons and granule-containing cells. Ganglionic development from embryonic day 11 through 18 comprises extensive maturation of developing principal neurons and a numerical decline of granule-containing cells. Some granule-containing cells with very few and small granules still persist at embryonic day 18. The mean catecholamine content per neuron increases from 0.044 femtomol at embryonic day 7 to 0.22 femtomol at embryonic day 15. Concomitantly, there is a more than 6-fold increase in tyrosine hydroxylase activity. Adrenaline has a 14% share in total catecholamines at embryonic day 15. Somatostatin levels are relatively high at embryonic day 7 (1.82 attomol per neuron) and are 10-fold reduced by embryonic day 15. Our results suggest the presence of two morphologically distinct sympathetic neuronal precursors at embryonic day 6: one with a binary choice to become a principal neuron or to die, the other one, a granule-containing cell, which alternatively may develop into a principal neuron, acquire a resting state or die.     

抗阿特拉津转基因大豆植株后代的遗传分析

本试验用阿特拉津溶液涂抹、荧光诱导动力学检测、分子杂交等方法对抗阿特拉津转基因大豆植株的后代进行了鉴定,在第二代及第三代中检测到了抗性基因的存在,表明从龙葵中得到的此抗阿特拉津 psbA 基因不仅能导人大豆叶绿体基因组中获得表达,而且可以遗传到后代。     

An evolutionary comparison of Acinetobacter calcoaceticus trpF with trpF genes of several organisms

The deduced amino acid sequence of Acinetobacter calcoaceticus N-(5'-phosphoribosyl) anthranilate isomerase (PRAI), which is coded by trpF, was compared with TrpF of Caulobacter crescentus, Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae, Neurospora crassa, and Aspergillus nidulans. Sixty percent of identical or similar amino acids were located in alpha/beta TIM (triose-phosphate isomerase) barrels and in residues important in substrate binding and catalysis. In addition, the analysis of trpF genes presented here supports a model by which fusion between separate trpC and trpF genes arose in some cases by in-frame deletions.