Random cloning of bent DNA segments from Saccharomyces cerevisiae and primary characterization of their structures

Summary Until recently it was assumed that any short segment of DNA could be approximated as a straight rod. Many instances, however, have been reported in which the helical axis is curved. We have devised a simple method for selective identification of DNA segments containing a sequence-directed bend (curvature), by means of a two-dimensional polyacrylamide gel electrophoresis. In order to gain general insights into the structural features and the functional significance of sequence-directed bends, a bank of plasmids carrying bent DNA inserts from the Saccharomyces cerevisiae total genomic DNA was constructed. Primary characterizations of a set of bent DNA segments randomly cloned from S. cerevisiae are presented. One of the cloned DNA segments appears to be derived from a yeast plasmid, the 2 m circle DNA.     

Comparative androecium morphogenesis ofSicyos angulatus andSechium edule (Cucurbitaceae)

“Androecium” ofSicyos angulatus andSechium edule is unique in having a solid central column below a head portion with thecae. Its morphogenesis was examined for the two species. The developmental course is composed of two distinct successive phases; (1) establishment of stamen primordia and (2) uplift of the stamen primordia caused by development of a central column below them. In the first phase, there is a difference between the two species; inSicyos angulatus, two bithecal and one monothecal stamen primordia are formed by congenital fusion among preformed five protrsions, whilst inSechium edule, three or four monothecal stamen primordia are formed without fusion. The central column is later produced by intercalary growth in a region below the stamen primordia in both species. Concomitant with central column development, the center of the floral primordium, which was surrounded by the early formed stamen primordia, is raised up to the top of the central column. The central column could be interpreted as a receptacular column, and not as congenitally fused stamen filaments, as currently believed. The “androecium” of the both species is considered an androecium complex, which consists of the stamens and a receptacular column.     

Interaction of rat lecithin-cholesterol acyltransferase with rat apolipoprotein A-I and with lecithin-cholesterol vesicles.

The interaction of rat plasma lecithin-cholesterol acyltransferase with lecithin-cholesterol vesicles and with rat apo-A-I was studied in comparison with that of human plasma lecithin-cholesterol acyltransferase to clarify the reaction mechanism of rat plasma lecithin-cholesterol acyltransferase. The interaction of both human and rat lecithin-cholesterol acyltransferase with lecithin-cholesterol vesicles was investigated by gel permeation chromatography on Superose 12. Both enzymes had almost the same affinity to the vesicles. The affinity of rat enzyme to rat apo-A-I was stronger than that of human enzyme to human apo-A-I when estimated on the apo-A-I-Sepharose 4B column. When human apo-A-I was added to the human enzyme/vesicle mixture which contained the enzyme-vesicle complex, the enzyme was effectively dissociated from the complex. But when rat apo-A-I was added to the rat enzyme/vesicle mixture, apo-A-I-enzyme-vesicle complex was still recognized by its elution pattern on gel permeation chromatography. This suggests that the mixture of rat enzyme, rat apo-A-I, and vesicles, which are the major components in the rat lecithin-cholesterol acyltransferase reaction, forms a stronger complex than do the components of the human reaction.     

Synthesis of glucosyl-inositol using a CGTase,isolation and characterization of the positional isomers,and assimilation profiles for intestinal bacteria

A novel disaccharide, glucosyl-inositol, was obtained by glucoamylase digestion of the oligoglucosylinositols synthesized frommyo-inositol as an acceptor and -cyclodextrin as a donor by transglucosylation of CGT ase fromBacillus ohbensis. The glucosyl-inositol fraction was separated by ion-exchange column chromatography and two positional isomers contained in the fraction were isolated by crystallization and HPLC on a graphitized carbon column. The structure of one of the two isomers isolated was fully determined as 1L(D)-5-O--D-glucopyranosyl-myo-inositol and another one was presumed as 1D-4-O--D-glucopyranosyl-myo-inositol from physicochemical data, H-H and C-H COSY NMR analyses and FAB-MS spectra. The disaccharide was assimilated byBifidobacterium adolescentis, B. breve, B. infantis andB. longum. On the other hand, it was not utilized byE. coli, Clostridium butyricum, C. clostridiiforme andKlebsiella pneumoniae.     

Pituitary adenylate cyclase activating polypeptide stimulates gallbladder motility in conscious dogs.

We investigated whether pituitary adenylate cyclase activating polypeptide (PA-CAP27 and PACAP38) had any effect on gallbladder motility in conscious dogs, in which force transducers were chronically implanted in the gastric antrum, duodenum and gallbladder. PACAP27 and PACAP38 were administered intravenously during the digestive and interdigestive states at doses of 30, 100 and 300 pmol/kg. By way of comparison, cholecystokinin octapeptide (CCK-OP) was administrated at doses of 3, 9 and 27 pmol/kg. As a result, each peptide evoked transient and tonic contractions both in the digestive and interdigestive states, and the effect on the motor index was dose dependent. PACAP27 and PACAP38 were 0.11 +/- 0.03 and 0.04 +/- 0.01 as potent as CCK-OP in the digestive state, and 0.18 +/- 0.04 and 0.02 +/- 0.01 in the interdigestive state, respectively, on a molar basis. Although PACAP27 and PACAP38 belong to the vasoactive intestinal polypeptide (VIP) family, intravenous administration of 300 pmol/kg of VIP had no effect on interdigestive gallbladder motility, but on the other hand inhibited gallbladder motility in the digestive state. The contractile effects of PACAP27 and PACAP38 were almost completely abolished by pretreatment with atropine or hexamethonium, but not with L364718. An in vitro study using canine gallbladder strips showed that PACAP27 and PACAP38 had no effect on spontaneous gallbladder motor activity evoked by electric field stimulation, CCK-OP or acetylcholine. It was concluded that PACAP27 and PACAP38 stimulate gallbladder motility in conscious dogs through a preganglionic cholinergic mechanism.     

Effects of eel atrial natriuretic peptide on NaCl and water transport across the intestine of the seawater eel

Summary Eel atrial natriuretic peptide inhibited the serosa-negative transepithelial potential difference and short-circuit current, accompanied by a decrease in NaCl and water absorption across the seawater eel intestine. Similar effects were obtained after treatment with N-terminally truncated eel atrial natriuretic peptide (5–27), indicating that N-terminal amino acids are not essential for the action of eel atrial natriuretic peptide. Although mammalian atrial natriuretic peptides also inhibited the short-circuit current, a 100-fold higher concentration was reuired to obtain the same effect as with eel atrial natriuretic peptide, indicating that eel atrial natriuretic peptide is 100 times as potent in eel intestine as the mammalian atrial natriuretic peptides. Similarly, in mammalian atrial natriuretic peptide, the four N-terminal amino acids had no significant effects. However, when the C-terminal tyrosine was removed, the potency of rat atrial natriuretic peptide was lowered. Compared with the effects of acetylcholine, serotonin and histamine, eel atrial natriuretic peptide was the most potent inhibitor, with 100% inhibition at 10^-7 M; 50% inhibition was obtained at 10^-2 M in acetylcholine, and 30% inhibition in serotonin (10^-5 M) and histamine (10^-3 M). These inhibitory effects of eel atrial natriuretic peptide were not diminished even in the presence of tetradoxin, and were mimicked by 8-bromoguanosine 3,5-cyclic monophosphate. Based on these results, structure-activity relationships of eel atrial natriuretic peptide and a possible mechanism of action of eel atrial natriuretic peptide are discussed.Abbreviations 8BrcGMP 8-bromoguanosine 3,5-cyclic monophosphate - eANP eel atrial natriuretic peptide - hANP human atrial natriuretic peptide - 5-HT 5-hydroxytryptamine creatine sulphate - I _sc short-circuit current - PD transepithelial potential difference - rANP rat atrial natriuretic peptide - R _t tissue resistance - TTX tetrodotoxin     

Fast protein separation by reversed-phase high-performance liquid chromatography on octadecylsilyl-bonded nonporous silica gel. II. Improvement in recovery of hydrophobic proteins.

Recovery of hydrophobic proteins from an RP-HPLC column was improved using a fast-separation RP-HPLC system operated at room temperature. Hydrophobic proteins such as ovalbumin could be adequately eluted from a nonporous octadecylsilyl (C18) spherical silica gel with a particle diameter of 20 microns using steep gradient elution with a 0.1% aqueous trifluoroacetic acid-acetonitrile system at a constant flow rate of 4 ml/min. Recoveries improved under fast separation since the protein sample suffered only a slight amount of irreversible denaturation on the hydrophobic surface of the stationary phase. The fast-separation system was also applied to the separation of larger proteins such as apo-ferritin (443 kDa) and thyroglobulin (669 kDa) as well as egg white proteins.     

A molecular genetic linkage map of mouse chromosome 19, including thelpr,Ly-44, andTdt genes

The mouselpr gene, which is an autosomal recessive gene causing autoimmune disease with features of human systemic lupus erythematosus and eventually death from severe immune-complex glomerulonephritis, has been mapped on chromosome 19. To determine its exact chromosomal location, a three-point backcross was carried out by mating (MRL/MpJ-lpr/lpr × MOL-MIT)F₁ × MRL/MpJ-lpr/lpr using the genesLy-44 (lymphocyte differentiation antigen-44) andTdt (terminal deoxynucleotidyl transferase) as markers. The following order of genes is proposed, with the distances between genes given in parentheses: centromere-Ly-44 (19.3 cM)-lpr (6.1 cM)-Tdt-telomere. TheLy-44 ^a andTdt ^a alleles are found in all laboratory strains and in the wild Western European subspecies,domesticus andbrevirostris. In contrast, theLy-44 ^b andTdt ^b alleles are found in some Asian subspecies, Chinese mice of wild origin,yamashinai andmolossinus. Furthermore the thirdTdt allele,Tdt ^c , is detected incastaneus.Some of the data in this study were previously presented at the 4th Mouse Gene Mapping Workshop, Annapolis, Maryland, in November 1990.