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.     

Detection of point mutation in the tyrosinase gene of a Japanese albino patient by a direct sequencing of amplified DNA

Summary Enzymatic DNA amplification and direct DNA sequencing were used to detect a mutation in the tyrosinase gene of an albino patient. Single-base change could be detected by direct sequencing. This base change (G to A) is thought to result in an amino acid change (Arg to Gln) in tyrosinase of the patient.     

Effects of water level fluctuation on the growth ofNelumbo nucifera Gaertn. in Lake Kasumigaura,Japan

Investigations were made of the growth ofNelumbo nucifera, an aquatic higher plant, in a natural stand in Lake Kasumigaura. A rise of 1.0 m in the water level after a typhoon in August 1986 caused a subsequent decrease in biomass ofN. nucifera from the maximum of 291 g d.w. m⁻² in July to a minimum of 75 g d.w. m⁻². The biomass recovered thereafter in shallower regions. The underground biomass in October tended to increase toward the shore. The total leaf area index (LAI) is the sum of LAI of floating leaves and emergent leaves. The maximum total LAI was 1.3 and 2.8 m² m⁻² in 1986 and 1987, respectively. LAI of floating leaves did not exceed 1 m² m⁻². The elongation rates of the petiole of floating and emergent leaves just after unrolling were 2.6 and 3.4 cm day⁻¹, respectively. The sudden rise in water level (25 cm day⁻¹) after the typhoon in August 1986 caused drowning and subsequent decomposition of the mature leaves. Only the young leaves were able to elongate, allowing their laminae to reach the water surface. The fluctuation in water level, characterized by the amplitude and duration of flooding and the time of flooding in the life cycle, is an important factor determining the growth and survival ofN. nucifera in Lake Kasumigaura.     

Roles of the respiratory Na+ pump in bioenergetics of Vibrio alginolyticus

Bioenergetic characteristics of Na+ pump-defective mutants of a marine bacterium Vibrio alginolyticus were compared with those of the wild type and revertant. Generation of membrane potential and motility at pH 8.5 in the mutants were completely inhibited by a proton conductor, carbonylcyanide m-chlorophenylhydrazone, whereas those in the wild type or revertant were resistant to the inhibitor. Motility and amino acid transport were driven by the electrochemical potential of Na+ not only in the wild type or revertant but also in the mutants. In the absence of the proton conductor, motility and amino acid transport of the mutants did not significantly differ from those of the wild type or revertant even at pH 8.5, where the Na+ pump has maximum activity. Therefore, the electrochemical potential of Na+ in the mutants seemed to be maintained at a normal level by a respiration-dependent H+ pump and Na+/H+ antiporter. On the other hand, growth of the mutants became defective as the medium pH increased, especially on minimal medium. These results indicate that the Na+ pump is an important energy-generating mechanism when nutrients are limited at alkaline pH.     

Studies on the development of water maze-learning ability in rats (3). Effect of the learning schedule on learning acquisition

The effect of different learning schedules massed or distributed practice conditions (3 trials a day for 3 days), on water-filled multiple T-maze learning ability of 8-week-old SPF Wistar-Imamichi rats was investigated. Although the mean number of errors decreased day by day in both groups, the number of errors in a given day and the total number of errors in 3 days did not differ significantly between the two groups. A tendency toward a decrease in the number of errors was observed as the trials proceeded in the group with distributed practice but not in the group with massed practice. The result suggests that a certain time period for rest after each trial is necessary to acquire the memory.     

Evidence for unique homologous peptide sequences around the glycosylated seryl and threonyl residues in polysialoglycoproteins isolated from the unfertilized eggs of the Pacific salmon Oncorhynchus keta

Structures of glycopeptides obtained by exhaustive Pronase digestion of high molecular weight (1.7 X 10(5)) salmon egg polysialoglycoprotein have been elucidated. Six principal glycopeptides isolated by gel chromatography and DEAE-Sephadex A-25 chromatography in the absence or presence of borate ion were analyzed for their carbohydrate and amino acid composition, as well as amino acid sequence, and found to be of two distinct types: glycotripeptides, Thr*-Ser*-Glu, and glycotetrapeptides, Thr*-Gly-Pro-Ser, where an asterisk indicates the amino acid residues to which either the Gal beta 1----3GalNAc or Fuc alpha 1----3GalNAc beta 1----3Gal beta 1----4Gal beta 1----3GalNAc chain is attached. Their final yield corresponds to 64% of the original desialylated glycoprotein. In view of the simple amino acid composition of salmon egg polysialoglycoprotein (molar ratio Asp2Thr2Ser3Glu1Pro1Gly1Ala3) and the result of alkaline beta-elimination indicating three carbohydrate units linked to two of two threonine and one of three serine residues, a unique primary structure comprising repetitive sequences of the above two types of glycopeptides, which are interspersed by short nonglycosylated peptides consisting of alanine and aspartic acid, has been proposed for the core protein. The molecular secondary ion mass spectra of underivatized glycopeptides were used to obtain their structural information. The anomeric configuration of the proximal sugar-peptide linkages was proven to be alpha by proton nuclear magnetic resonance spectroscopy. This is the first systematic reported study of O-glycosidically linked glycopeptides by these instrumental methods.     

Purification and properties of extracellular glucosyltransferase synthesizing 1,6-, 1,3-alpha-D-glucan from Streptococcus mutans serotype a

An extracellular glucosyltransferase (sucrose: 1,6-, 1,3-alpha-D-glucan 3-alpha- and 6-alpha-D-glucosyltransferase, EC 2.4.1.-) of Streptococcus mutans HS6 (serotype a) was purified from culture supernatant by DEAE-Sepharose chromatography and preparative isoelectric focusing. The molecular weight measured by SDS-PAGE was 159 000 and the isoelectric point was pH 4.9. The specific activity was 89.7 i.u. (mg protein)-1 and the optimum pH was 6.0. The Km value for sucrose was 4.9 mM and the enzyme activity was not stimulated by exogenous dextran T10. Glucan was synthesized de novo from sucrose by the purified enzyme and consisted of 49.1 mol% 1,6-alpha-linked glucose and 33.9 mol% 1,3-alpha-linked glucose, with 13.6 mol% terminal glucose and 3.3 mol% 1,3,6-alpha-branched glucose.