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.     

Measurement of Serine Acetyltransferase Activity in Crude Plant Extracts by a Coupled Assay System Using Cysteine Synthase

Serine acetyltransferase (SATase) (EC 2.3.1.30 [EC] ) catalyzes theformation of Oacetyl-L-serine (OAS) from L-serine in the presenceof acetyl-CoA. A novel assay method was developed for measuringthis enzyme activity in extracts from plant tissues. The assayconsists of a coupled system in which the OAS formed is convertedto cysteine by the addition of cysteine synthase (CSase) (EC4.2.99.8 [EC] ). Cysteine thus formed is determined colorimetricallyand serves as a measure for SATase activity. This method israpid, simple and sensitive, and can be readily adapted formeasurement of SATase activity in crude tissue extracts or homogenates. (Received January 14, 1987; Accepted April 27, 1987)     

Mutations Affecting Acetylcholine Levels in the Nematode Caenorhabditis elegans

Gene cha-1.unc-17 of the nematode Caenorhabditis elegans is a complex gene, consisting of at least two complementation groups. One part (cha-1 region) of the gene encodes the enzyme choline acetyltransferase (ChAT), but the function of the other part (unc-17 region) is still unclear. We measured the ChAT activity and ACh levels of the cha-1 and unc-17 complex gene mutants. We show here that alterations in ACh levels, rather than the ChAT activity, reflect abnormal phenotypes accompanying cha-1.unc-17 mutations, that is, the decreased ACh levels in cha-1 mutations and abnormal accumulation in unc-17 mutations. Our results suggest that the unc-17 region may encode functions necessary for storage and/or release of ACh at the presynaptic level.     

Molecular cloning of a cDNA coding for 70 kilodalton subunit of soluble guanylate cyclase from rat lung

A complementary DNA clone corresponding to the 70 kDa subunit of soluble guanylate cyclase (EC 4.6.1.2) of rat lung has been isolated. The primary structure of the cDNA consisted of 3063 nucleotides including a 1857-nucleotide coding region for 619 amino acids, and the calculated molecular weight was 70476. Blot hybridization of total poly(A)+RNAs from rat tissues detected a mRNA of about 3.4 kilobases. The amount of mRNA was abundant in lung, cerebrum and cerebellum, moderate in heart and kidney, and low in liver and muscle. Southern blot analysis of high molecular weight genomic DNA from rat liver indicated the presence of one gene in the rat haploid genome. The amino acid sequence of the 70 kDa subunit has partial homology with particulate guanylate cyclase from sea-urchin sperm, and protein phosphatase inhibitor I.     

Existence of a novel enzyme, pyrroloquinoline quinone-dependent polyvinyl alcohol dehydrogenase, in a bacterial symbiont, Pseudomonas sp. strain VM15C.

A novel enzyme, pyrroloquinoline quinone (PQQ)-dependent polyvinyl alcohol (PVA) dehydrogenase, was found in and partially purified from the membrane fraction of a PVA-degrading symbiont, Pseudomonas sp. strain VM15C. The enzyme required PQQ for PVA dehydrogenation with phenazine methosulfate, phenazine ethosulfate, and 2,6-dichlorophenolindophenol as electron acceptors and did not show PVA oxidase activity leading to H2O2 formation. The enzyme was active toward low-molecular-weight secondary alcohols rather than primary alcohols. A membrane-bound PVA oxidase was also present in cells of VM15C. Although the purified oxidase showed a substrate specificity similar to that of PQQ-dependent PVA dehydrogenase and about threefold-higher PVA-dehydrogenating activity with phenazine methosulfate or phenazine ethosulfate than PVA oxidase activity with H2O2 formation, it was shown that the enzyme does not contain PQQ as the coenzyme, and PQQ did not affect its activity. Incubation of the membrane fraction of cells with PVA caused a reduction in the cytochrome(s) of the fraction.     

Evaluation of statistical precision and design of efficient sampling for the population estimation based on frequency of occurrence

The binomial sampling to estimate population density of an organism based simply upon the frequency of its occurrence among sampled quadrats is a labour-saving technique which is potentially useful for small animals like insects and has actually been applied occasionally to studies of their populations. The present study provides a theoretical basis for this convenient technique, which makes it statistically reliable and tolerable for consistent use in intensive as well as preliminary population censuses. Firs, the magnitude of sampling error in relation to sample size is formulated mathematically for the estimate to be obtained by this indirect method of census, using either of the two popular models relating frequency of occurrence (p) to mean density (m), i.e. the negative binomial model, p=1−(1+m/k)^−k, and the empirical model, p=1−exp(−am^b). Then, the equations to calculate sample size and census cost that are necessary to attain a given desired level of precision in the estimation are derived for both models. A notable feature of the relationship of necessary sample size (or census cost) to mean density in the frequency method, in constrast to that in the ordinary census, is that it shows a concave curve which tends to rise sharply not only towards lower but also towards higher levels of density. These theoretical results make it also possible to design sequential estimation procedures based on this convenient census technique, which may enable us with the least necessary cost to get a series of population estimates with the desired precision level. Examples are presented to explain how to apply these programs to acutal censuses in the field.     

The glycoprotein nature of solubilized muscarinic acetylcholine receptors from bovine cerebral cortex

Muscarinic acetylcholine receptors were solubilized from bovine cerebral cortex with 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate. The so-obtained receptors could be precipitated by Wheat Germ (73%), Concanavalin A (55%), Lens Culinaris (36%) and Ricinus Communis (26%), but not by Peanut, Dolichus Biflorus and Ulex Europaeus. On Wheat Germ- and Concanavalin A-affinity chromatography, the solubilized muscarinic receptors were retained on both columns and subsequently eluted with N-acetylglucosamine and alpha-methyl-D-mannoside, respectively. A high concentration (100 micrograms/ml) of Wheat Germ or Concanavalin A did not interfere with Z-[3H]quinuclidinyl benzilate binding, thereby suggesting that the lectin binding sites are not directly involved in the receptor binding function. These solubilized muscarinic receptors are postulated to contain carbohydrate residues, N-acetyl-glucosamine, mannose and galactose, as glycoprotein.     

Competition between laboratory populations of green leafhoppers,Nephotettix spp. (Homoptera: Cicadellidae)

Intra- and interspecific competition between laboratory populations of four green leafhoppers, Nephotettix spp. was studied in the laboratory under three different temperature regimes of 24°C, 27°C and 30°C. For the single-species population of the three tropical species, the equilibrium density increased as the temperature increased. On the other hand, for the temperature species N. cincticeps, the highest equilibrium density was at the intermediate temperature and the lowest at high temperature. Interspecific interactions between two tropical (N. virescens vs. N. nigropictus), a tropical and a temperature (N. virescens vs. N. cincticeps) and a rice-feeding and a grass-inhabiting (N. virescens vs. N. malayanus) Nephotettix species were also studied in the laboratory at the three temperature regimes. Temperature differentially affected the outcome of competition between two Nephotettix species. Between N. virescens and N. nigropictus, the latter was more successful over the former at low and intermediate temperatures, while the former was more successful at high temperature. Between N. virescens and N. cincticeps, the temperate species inhibited the growth of the tropical species at low temperature while the tropical species inhibited the growth of the temperate species at high temperature. At intermediate temperature, the population of N. virescens persisted at a slightly higher density over the population of N. cincticeps. Between the rice-feeding N. virescens and the grass-inhabiting N. malayanus, regardless of temperature the population density of the latter was greatly reduced and later became extinct while the population of the former continued its growth. These consequences of competition between two Nephotettix species conformed fairly well to those predicted by theLotka-Volterra model using demographic parameters specified for each species.     

Breathing during sleep with mild hypoxia

To investigate ventilatory response to mild hypoxia during non-rapid-eye-movement sleep, we administered approximately 16% O2 (which corresponds to concentrations found in commercial high altitude air craft) to 12 normal subjects by using a Venturi mask, which did not alter the breathing pattern during this study. Under mild hypoxia, inspiratory minute ventilation during sleep showed an initial rapid increase (P less than 0.001) but then declined significantly (P less than 0.001) and stabilized. Stable levels differed among individuals and, compared with those measured before hypoxia, were significantly lower in some subjects, higher in one, and essentially unchanged in the others. The initial rapid increase in minute ventilation after mild hypoxia during sleep correlated with the respective values of hypoxic ventilatory response during the awake state (P less than 0.01), but the final lowered levels did not. We conclude that the ventilatory response after mild hypoxia during sleep is biphasic and hypoxic depression exerts considerable influence on ventilation under mild hypoxia during sleep. So we should take hypoxic depression into consideration to evaluate the response to hypoxia during sleep.     

An ecological study of soils in the Highlands of western Tibet I. Soils along an iso-altitudinal transect across western Tibet

A variety of soil studies were carried out along a 920-km transect running SE to NW from near the border with northern Nepal, through the Western Tibet Highlands (soils sampled at six locations at an elevation of about 4200 m), to the Takla Makan Desert. This transect, which parallels the China-India border, covers a range of aridities. Annual precipitation decreased exponentially (from 169 mm to ca. 50 mm) north-westwards along the transect. The humidity index also decreased exponentially to the desert zone in the Western Tibet Highlands, and decreased further in the Takla Makan Desert because of the high temperature in the latter area. Vegetation changed fromCaragana thorn-bush steppe, throughArtemisia sparse steppe, to desert. Soil properties were studied in relation to the humidity index. Organic C, total N, cation exchange capacity, and very low C/N ratio values (a maximum of 12.8) of soils decreased with the decrease in humidity index. In contrast, carbonate, pH (KCl), and sulfate increased exponentially. Available P and ammonia content were inversely related to the abundance of carbonate, whereas nitrate increased where carbonate was abundant. Illite was the most abundant of the clay minerals, followed in order by kaolinite and montmorillonite.