Sequences of cDNAs for human salivary and pancreatic α-amylases

The nucleotide sequences of the cloned human salivary and pancreatic α-amylase cDNAs correspond to the continuous mRNA sequences of 1768 and 1566 nucleotides, respectively. These include all of the amino acid coding regions. Salivary cDNA contains 200 bp in the 5′-noncoding region and 32 in the 3′-noncoding region. Pancreatic cDNA contains 3 and 27 bp of 5′- and 3′-noncoding regions, respectively. The nucleotide sequence humology of the two cDNAs is 96% in the coding region, and the predicted amino acid sequences are 94% homologous.Comparison of the sequences of human α-amylase cDNAs with those previously obtained for mouse α-amylase genes (Hagenbuchle et al., 1980; Schibler et al., 1982) showed the possibility of gene conversion between the two genes of human α-amylase.     

Morphological pathway of flagellar assembly in Salmonella typhimurium.

The process of flagellar assembly was investigated in Salmonella typhimurium. Seven types of flagellar precursors produced by various flagellar mutants were purified by CsCl density gradient protocol. They were characterized morphologically by electron microscopy, and biochemically by two-dimensional gel electrophoresis. The MS ring is formed in the absence of any other flagellar components, including the switch complex and the putative export apparatus. Four proteins previously identified as rod components, FlgB, FlgC, FlgF, FlgG, and another protein, FliE, assemble co-operatively into a stable structure. The hook is formed in two distinct steps; formation of its proximal part and elongation. Proximal part formation occurs, but elongation does not occur, in the absence of the LP ring. FlgD is necessary for hook formation, but not for LP-ring formation. A revised pathway of flagellar assembly is proposed based on these and other results.     

Correlation between Supercoiling and Conformational Motions of the Bacterial Flagellar Filament

The bacterial flagellar filament is a very large macromolecular assembly of a single protein, flagellin. Various supercoiled states of the filament exist, which are formed by two structurally different conformations of flagellin in different ratios. We investigated the correlation between supercoiling of the protofilaments and molecular dynamics in the flagellar filament using quasielastic and elastic incoherent neutron scattering on the picosecond and nanosecond timescales. Thermal fluctuations in the straight L- and R-type filaments were measured and compared to the resting state of the wild-type filament. Amplitudes of motion on the picosecond timescale were found to be similar in the different conformational states. Mean-square displacements and protein resilience on the 0.1 ns timescale demonstrate that the L-type state is more flexible and less resilient than the R-type, whereas the wild-type state lies in between. Our results provide strong support that supercoiling of the protofilaments in the flagellar filament is determined by the strength of molecular forces in and between the flagellin subunits.     

Maternal care in the red-headed spruce web-spinning sawfly,Cephalcia isshikii (Hymenoptera: Pamphiliidae)

We describe oviposition and maternal behavior in the sawfly Cephalcia isshikiiand examine the adaptive significance of this behavior. Females deposited eggs in a single but loose cluster on needles of terminal twigs of spruces, Piceaspp., and remained with the eggs usually on the underside of the twig facing toward the tip. The female attended her eggs until death without taking food but did not follow the first-instar larvae that moved from natal needles even if she survived until then. When the female was disturbed, she usually moved toward the source and attempted to bite it. Though at much lower frequencies, this aggressive behavior was also observed in gravid females and even in males. Field observations and female removal experiments indicated that the female enhanced the survival of the eggs through the reduction of arthropod prédation.     

Purification and properties of 3 alpha-hydroxyglycyrrhetinate dehydrogenase of Clostridium innocuum from human intestine

3 alpha-Hydroxyglycyrrhetinate dehydrogenase of Clostridium innocuum, isolated from human intestinal bacteria, was capable of converting 3-ketoglycyrrhetic acid to 3 alpha-hydroxyglycyrrhetic acid. The enzyme was purified to homogeneity by means of butyl-Toyopearl 650M, Sephadex G-150, Matrex Red A, Toyopearl HW-55S, and isoelectric focusing column chromatographies. The purified enzyme showed a specific activity of 156 mumol/min.mg toward 3 alpha-hydroxyglycyrrhetic acid, and showed a single band on SDS-polyacrylamide gel electrophoresis. The apparent molecular weight was 53,000, as estimated by gel filtration, and 30,000, as judged by SDS-polyacrylamide gel electrophoresis. Its isoelectric point was 5.2. The enzyme showed absolute specificity for the 3 alpha-hydroxyl and 3-ketonic groups of 18 alpha- or 18 beta-glycyrrhetic acid and required NADP+ and NADPH as cosubstrates. The enzyme did not act on any 3 alpha-hydroxyl or 3-ketonic group of steroids or bile acids. The enzyme is a novel type of enzyme, defined as 3 alpha-hydroxy-glycyrrhetinate dehydrogenase, being quite different from 3 alpha-hydroxysteroid dehydrogenase [EC 1.1.1.50].     

Actions of exogenous heparan sulfate and hyaluronic acid on growth and thymidine incorporation of normal and transformed human fibroblasts. A comparison with the effects of high cell density and low serum concentration and a warning against thymidine incorporation as a measure of DNA synthesis

Treatment of normal human (WI-38) cells with exogenous heparan sulfate (HS) reduced cell growth and incorporation of radio-isotope-labeled thymidine (TdR) into DNA. In spite that growth of their transformants (WI-38 CT-1) was enhanced by HS treatment, transformed cells also decreased in TdR incorporation thereby. This peculiar observation was explained by a reduction of TdR uptake, leading to a decrease in specific radioactivity of newly synthesized DNA. The changes in cell growth and TdR incorporation by HS treatment were revealed to be similar to the changes with increasing cell density rather than by serum starvation.     

Inhibition of pentagastrin-stimulated gastric acid secretion by intraileal administration of bile and elevation of plasma concentrations of gut glucagon-like immunoreactivity in anesthetized dogs

The effects of intraileal administration of bile on gastric acid secretion stimulated by a submaximal dose of intravenous pentagastrin infusion and on plasma concentrations of gut glucagon-like immunoreactivity (gut GLI) were studied in anesthetized dogs. Gastric acid secretion was measured for a 2-h period at 15-min intervals before and after intraluminal instillation of test solutions. 100 ml of canine bladder bile diluted to 10% in saline evoked a significant inhibition (20%) of gastric acid secretion. The inhibition of gastric acid secretion was accompanied by an elevation of plasma concentration of gut GLI, whereas saline instillation (in controls) caused no responses. Although the inhibition of gastric acid secretion and the elevation of plasma gut GLI are parallel phenomena, gut GLI can be reasonably postulated as one of the candidate mediators of bile-induced inhibition of gastric acid secretion, since its structurally related peptides, pancreatic glucagon, glicentin and oxyntomodulin have been reported as inhibitors of gastric acid secretion.     

Effect of intraluminal bile or bile acids on release of gut glucagon-like immunoreactive materials in the dog

The true biological role of gut glucagon-like immunoreactive materials (gut GLI) is still unknown, although the stimulatory effect of intraluminal nutrients on the secretion of gut GLI has been described. The present authors, using the canine intestinal loop prepared from the terminal portion of the ileum, investigated how gut GLI would respond to digestive juice or its components. When bladder bile collected from another dog and diluted to 10% in saline was instilled into canine ileal loop, gut GLI in a branch of regional mesenteric vein was elevated significantly. Cholic acid suspended in saline (0.25 g/50 ml) also stimulated gut GLI secretion in the similar pattern to that of bile administration. On the other hand, 154 mM NaHCO3 which is a major inorganic component of pancreatic juice did not affect the venous level of gut GLI.