Novel surface lipids of diapausing Manduca sexta pupae. Long chain oxoalcohol esters of acetoacetic, hydroxybutyric, and acetic acids

Ester components in the surface wax from diapausing tobacco hornworm pupae, Manduca sexta L., were separated by thin layer chromatography and gas-liquid chromatography, and characterized by infrared spectroscopy and gas-liquid chromatography-mass spectrometry. Three groups of esters were identified as natural derivatives of acetic acid, acetoacetic acid, and 3-hydroxybutyric acid. The major ester fraction was identified as a mixture of C26 (10%), C27 (5%), and C28 (85%) oxoalcohol esters of acetoacetic acid. The major homolog consisted of equal amounts of 11-oxooctacosanyl 3-oxobutanoate and 12-oxooctacosanyl 3-oxobutanoate. Lesser amounts of 11- and 12-oxooctacosanyl and n-octacosanyl esters of acetic and 3-hydroxybutyric acids were also identified. The chain length distributions of these C26, C27, and C28 oxoalcohol and n-primary alcohol ester moieties, as well as the isomeric ratios for the 11- and 12-oxoalcohol isomers, were similar to the oxoaldehydes and unesterified oxoalcohols previously identified by Buckner et al (Buckner, J. S., Nelson, D. R., Haak, H., and Pomonis, J. G. (1984) J. Biol. Chem. 259, 8452-8470) as lipid components of the surface wax of M. sexta pupae.     

A stable isotope trace method to measure silicic acid uptake by marine phytoplankton.

A tracer method is described that uses the stable isotope ³⁰Si to measure rates of silicic acid uptake by diatom cultures and natural populations of marine phytoplankton. The method involves (i) incubation of organisms requiring silicic acid for growth in the presence of ³⁰Si-labeled silicic acid, (ii) collection of the resulting particulate silicon, (iii) conversion of the particulate silicon to BaSiF₆, (iv) determination of the ³⁰Si content of BaSiF₆ by solid sample mass spectrometry, and (v) calculation of the uptake rate from the ³⁰Si enrichment of the particulate matter during the incubation. The maximum overall error in the uptake rate measurement is ±10%.     

Enzymes of vitamin B6 degradation. Purification and properties of 5-pyridoxic-acid oxygenase from Arthrobacter sp

5-Pyridoxic-acid oxygenase, a cytoplasmic enzyme formed when Arthrobacter Cr-7 is grown with pyridoxine as a sole source of carbon and nitrogen, was purified about 190-fold to homogeneity from fully induced cells. The enzyme catalyzes Reaction a, (Formula: see text) the essential ring-opening step in the degradation of pyridoxine, and provides a second example of an FAD-dependent oxygenase that adds both two hydrogen and two oxygen atoms to its substrate. 5-Pyridoxic-acid oxygenase has an isoelectric point of 4.6, functions optimally between pH 7 and 8, appears to contain a single subunit of Mr = 51,000 and one FAD (but no iron) per subunit, and is readily resolved by precipitation with ammonium sulfate at pH 3.0. FMN and riboflavin do not replace FAD as coenzyme, but their presence enhances a normally minor side reaction (Reaction b) NAD(P)H + H+ + O2----NAD(P)+ + H2O2 (b) catalyzed by the holoenzyme. Reaction b also is enhanced when the poorly utilized analogues, 3-hydroxy-2-methylpyridine-5-carboxylic acid or NADH, replace 5-pyridoxic acid or NADPH, respectively, as substrates in Reaction a. Each of the enzymes required in two different pathways for degradation of pyridoxine to anabolic intermediates has now been studied. A comparison of these two pathways and their enzymes is provided.     

Dehydroheliamine,a trace alkaloid from the saguaro,Carnegiea gigantea (cactaceae)

Extraction of Carnegiea gigantea yielded a new 3,4-dihydroisoquinoline alkaloid, dehydroheliamine; the structure was confirmed by synthesis.     

Identification, purification, and characterization of phosphotyrosine-specific protein phosphatases from cultured chicken embryo fibroblasts.

Tyrosine phosphorylation catalyzed by a unique class of protein kinases is an important process in both normal cell proliferation and oncogenic transformation. In this study, phosphoprotein phosphatases specific for the dephosphorylation of phosphotyrosine residues were partially purified from secondary chicken embryo fibroblasts, using 32P-labeled immunoglobulin G phosphorylated by pp60src as substrate. Crude cell extracts contained ca. 70% of the activity in the soluble form and ca. 30% associated with a crude membrane fraction. The soluble activity was purified by using DEAE-cellulose and carboxymethyl cellulose column chromatography and gel filtration, and at least three enzyme species of apparent Mr 55,000 (pTPI), 50,000 (pTPII), and 95,000 (pTPIII)--comprising ca. 20, 45, and 35%, respectively, of the total activity--were resolved. All three enzymes possessed somewhat similar properties. They had a pH optimum of about 7.4, they were inhibited by Zn2+, vanadate, ATP, and ADP, and they were unaffected by divalent metal cations, EDTA, and F- under standard assay conditions employing a physiological ionic strength. These properties suggest that they represent a class of enzymes distinct from well-known phosphoseryl-phosphothreonyl-protein phosphatases and that dephosphorylation of phosphotyrosine-containing proteins may be carried out by a unique family of phosphoprotein phosphatases. Transformation by Rous sarcoma virus resulted in a small increase in phosphotyrosyl-protein phosphatase activity.     

First descriptions of Coelometopini pupae (Coleoptera: Tenebrionidae) from Australia,Southeast Asia and the Pacific region,with comments on phylogenetic relationships and antipredator adaptations

Abstract. The pupal stage of ten Coelometopini species occurring in Australia, New Guinea, Southeast Asia and the Pacific region are described and a key for their identification is provided. The species are Chrysopeplus expolitus Broun, Derosphaerus hirtipes Kaszab, Hypaulax crenata (Boisduval), Leprocaulus borneensis Kaszab, Metisopus purpureipennis Bates, Promethis carteri Kaszab, P. nigra (Blessig), P. quadraticollis (Gebien), P. quadricollis Pascoe and P. sulcigera (Boisduval). The gin trap structures of D. hirtipes and P. quadraticollis are described in detail using scanning electron micrographs. A summary of antipredator structures of all known Coelometopini pupae is given. The phylogenetic value of pupal characters is assessed at intra‐ and intergeneric levels within the tribe.     

Internal anion binding site and membrane potential dominate the regulation of proton pumping by the chromaffin granule ATPase

Effects of anions and membrane potential on the reconstituted proton pump from chromaffin granules were investigated. When acetate was present inside of the vesicles, ATP-dependent proton uptake was absolutely dependent on external chloride. Without external chloride, however, substantial proton uptake was observed when chloride or sulfate was present inside of the vesicles. Inside negative membrane potential drove ATP-dependent proton uptake regardless of the anion species present inside or outside of the vesicles. It is concluded that the internal anion binding site and membrane potential regulate the proton pumping activity of the ATPase.