The effect of gyrase inhibitors and cyclic AMP on induction and glucose repression of the 6-hydroxy-nicotine oxidases in Arthrobacter oxidans

The induction by d,l-nicotine of the enantiozymes 6-hydroxy-L-nicotine oxidase and 6-hydroxy-D-nicotine oxidase in Archrobacter oxidans was differently affected by the inhibitors of Escherichia coli gyrase, novobiocin and nalidixic acid. These compounds inhibited 6-hydroxy-L-nicotine oxidase induction slightly, but led to an increase in the level of 6-hydroxy-D-nicotine oxidase activity. Furthermore, the specific repression by glucose of 6-hydroxy-D-nicotine oxidase synthesis was not abolished by the addition of cAMP but by that of novobiocin.Abbreviations 6-HDNO 6-hydroxy-D-nicotine oxidase - 6-HLNO 6-hydroxy-L-nicotine oxidase - cAMP cyclic 3,5-adenosine monophosphate - Enzymes Adenylate cyclase - ATP pyrophosphate-lyase (cyclizing) (EC 4.6.1.1) - cAMP-phosphodiesterase 3:5-cyclic-nucleotide 5-nucleotido-hydrolase (EC 3.1.4.17) - DNA gyrase DNA topoisomerase II (EC 5.99) - DNA polymerase deoxynucleosidetriphosphate: DNA desoxynucleotidyl-transferase (EC 2.7.7.7) - 6-hydroxy-L-nicotine oxidase 6-hydroxy-L-nicotine: oxygen oxidoreductase (EC 1.5.3.5) - 6-hydroxy-D-nicotine oxidase 6-hydroxy-D-nicotine: oxygen oxidoreductase (EC 1.5.3.6) - -lactamase penicillin amido--lactamhydrolase (EC 3.5.2.6) - nicotine dehydrogenase nicotine: (acceptor)6-oxidoreductase (hydroxylating) (EC 1.5.99.4)     

AIRFLOW PATTERNS AROUND SOME EARLY SEED PLANT OVULES AND CUPULES: IMPLICATIONS CONCERNING EFFICIENCY IN WIND POLLINATION

Aerodynamic analyses showing characteristic airflow patterns and the potential for wind-mediated pollination are presented for models of Paleozoic (Carboniferous) ovules and ovulate cupules (i.e., Genomosperma kidstoni, G. latens, Salpingostoma dasu, Physostoma elegans, Eurystoma angulare, and Stamnostoma huttonense). Lobes on ovules and cupules are shown to produce localized regions of turbulent flow with a concomitant reduction in airflow velocity. Data based upon models that mimic the characteristics of windborne pollen (= pseudopollen) show that these regions of turbulent flow correspond to those in which suspended pseudopollen impact with ovule and/or cupule surfaces. These data have bearing on a sequence of ovule morphologies purported to show the evolution of the integument by the progressive reduction in length of “preintegumentary” lobes and their acropetal fusion. As the preintegumentary lobes of the models studied consolidate around the megasporangium, regions of turbulent flow and high pseudopollen impact become localized around the pollen chamber or salpinx. The general morphologic trend envisioned for the evolution of the ovule is seen to be associated with an aerodynamic streamlining and an increased potential for wind-mediated pollination. Data for hair-bearing ovules and for ovulate cupules are discussed within the context of possible selective pressures favouring streamlining.     

Simultaneous Rates of Ribonucleic Acid and Deoxyribonucleic Acid Syntheses for Estimating Growth and Cell Division of Aquatic Microbial Communities

A method for measuring rates of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) syntheses using a single radioactive precursor has been devised and tested using bacterial cultures and natural assemblages of marine and freshwater microorganisms. The procedure is based upon the uptake and incorporation of exogenous [³H]adenine into cellular adenosine triphosphate and deoxyadenosine triphosphate pools which serve as the immediate precursors for the adenine incorporated into RNA and DNA, respectively. It is proposed that the DNA/RNA rate ratio is correlated with the specific growth rate of microorganisms and can be used as an index for estimating and comparing the productivities of microbial assemblages in nature. This technique can also be used to detect discontinuous growth and cell division processes which frequently occur in surface plankton populations. The DNA/RNA rate ratios measured in a variety of aquatic ecosystems ranged from 3.3 to 31.8% without significant correlation to total microbial biomass.     

Purification and characterization of two β-N-acetylhexosaminidases from the tobacco hornworm,Manduca sexta (L.) (Lepidoptera: Sphingidae)

β-N-Acetylhexosaminidases were detected in 10 insects including species of Lepidoptera, Coleoptera, Hemiptera, and Orthoptera. Two enzymes were purified from the tobacco hornworm, Manduca sexta (L.). EI was detected in larval and pharate pupal molting fluid, integument, and pupal hemolymph while EII was found in larval and pupal hemolymphs. They are acidic hydrolases with similar molecular weights (6.1 × 10⁴), molar extinction coefficients at 280 nm (1.9 × 10⁵ liters mol^?1 cm^?1), and pH optima (pH 6). They differ in the number of polypeptide chains per molecule (EI is a single chain and EII consists of two polypeptide chains), amino acid composition, extent of glycosylation (EII is probably a glycoprotein), isoelectric point (pI_EI = 5.9 and pI_EII ～- 5.1), tissue distribution, and reactivities toward nitrophenylated N-acetylglucosamine (k_cat,I = 328 s^?1 and k_cat,II = 103 s^?1) and N,N′-diacetylchitobiose (k_cat,I = 307 s^?1 and k_cat,II = 3 s^?1). These results suggest that EI is a chitinase and that EII may function as a hexosaminidase in vivo.     

A note on the structure of tail hairs from a pygmy hippopotamus (Choeropsis liberiensis)

The pygmy hippopotamus (Choeropsis liberiensis), like the Nile hippopotamus (Hippopotamus amphibius), defecates by backing into vertical objects while making a series of rapid, propellerlike tail movements that spread a mixture of urine and feces in a wide swath. Split hairs from the distal ventral surface of the pygmy hippopotamus tail were studied with the scanning electron microscope to determine whether the splitting was a normal character of the hair or was due to damage. The results suggest that splitting is a normal feature of the hair that may facilitate the dispersal of urine and feces.     

Plasminogen activator: The major secreted neutral protease of cultured skeletal muscle cells

Clonal mouse skeletal muscle cells which differentiate in culture and from synpases with neuronal cells were found to secrete high levels of protease activity as measured with an ¹²⁵I-fibrin assay. The secreted proteolytic activity was more than 90% dependent upon the presence of plasminogen in the medium, and had a pH optimum at 7 to 8. This activity was not inhibited by n-ethylmaleimide, pepstatin, EDTA, or EGTA. At millimolar concentrations, greater than 90% inhibition was obtained with either soybean typsin inhibitor, epsilon aminocaproic acid, Trasylol, or leupeptin. Almost complete inhibition occured with 1 mM diisopropylfluorophosphate suggesting the presence of a serine residue at the catalytic site. In contrast to the high levels of secreted activity, a lower steady-state level of cell-associated protease activity was detected in cell lysates. The high level of plasminogen activator secreted into the medium of cultured muscle cells suggests a role for such extracellular protease activity in myogenesis during development and remodeling following muscle injury. Such information may be useful in understanding the initial degeneration of neuromusclar contacts in experimental and pathologic denervation.     

The effect of re-release of Oryctes rhinoceros baculovirus in the biological control of rhinoceros beetles in Western Samoa

The Rhinoceros Beetle Project in Western Samoa has developed and successfully applied biological methods to control the rhinoceros beetle, a serious pest of coconut palms, by using two specific pathogens, a baculovirus (Family Baculoviridae), and an entomopathogenic fungus, Metarhizium anisopliae. The application of virus particularly has markedly suppressed the beetle population and helped revive the copra industry. The virus disease had established itself in the wild beetle population several years after its introduction at a level between 30 and 50%. At the same time an increase in beetle numbers and damage to palm trees was experienced. Therefore, a continuous release of virus into beetle-infested areas was proposed. It was argued that, considering the relatively high level of “natural” virus incidence, further releases of virus into the population would be futile. In a combined research and control program, virus was again re-released into the wild beetle population which was already virus infected. The results show that through re-release the virus level can be raised and the number of beetles and consequently the damage can be reduced. The techniques of the control methods are described. The virus release is very easy and cheap; it requires no chemicals, no special equipment, and it is particularly recommended in situations where breeding places are inaccessible or other methods such as plantation sanitation are either impossible or economically impractical. Above all, the methods are absolutely safe from the standpoint of environmental protection.     

Carbon Balance Studies of Glucose Metabolism in Rat Cerebral Cortical Synaptosomes

Synaptosomes were isolated from rat cerebral cortex and incubated with [U-14C]-, [1-14C]- or [6-14C]glucose. Glucose utilization and the metabolic partitioning of glucose carbon in products were determined by isotopic methods. From the data obtained a carbon balance was constructed, showing lactate to be the main product of glucose metabolism, followed by CO2, amino acids and pyruvate. Measuring the release of 14CO2 from glucose labelled in three different positions allowed the construction of a flow diagram of glucose carbon atoms in synaptosomes, which provides information about the contribution of the various pathways of glucose metabolism. Some 2% of glucose utilized was calculated to be degraded via the pentose phosphate pathway. Addition of chlorpromazine, imipramine or haloperidol at concentrations of 10(-5) M reduced glucose utilisation by 30% without changing the distribution pattern of radioactivity in the various products.     

Effects of zomepirac and indomethacin on renal blood flow and electrolyte excretion in anesthetized monkeys

Zomepirac sodium is a new inhibitor of prostaglandin cyclooxygenase with an $\text{in vitro}$ potency equivalent to indomethacin. Since inhibitors of prostaglandin synthesis have marked effects on renal hemodynamics, zomepirac may be expected to reduce renal blood flow (RBF) in a manner similar to indomethacin. This study compares the effects of zomepirac and indomethacin on RBF and electrolyte excretion in anesthetized Rhesus monkeys. Each experiment consisted of a control period followed by 3 or 4 drug treatment periods in which increasing doses of zomepirac (0.5 to 20 mg/kg) or indomethacin (0.5 to 10 mg/kg were given. Indomethacin (5 mg/kg) reduced RBF by 22% and the higher dose (10 mg/kg) reduced RBF by an additional 13%. Zomepirac had little effect on RBF in doses as high as 20 mg/kg. At any given dose the mean plasma concentration of zomepirac was equal to or greater than indomethacin. Peak indomethacin concentration was 48 μg/ml after the 10 mg/kg dose while the peak zomepirac, after 20 mg/kg, was 158 μg/ml. Neither drug had a significant effect on either glomerular filtration rate or excretion rate of sodium or potassium. Thus, zomepirac had only minimal effects on RBF while indomethacin decreased RBF of anesthetized monkeys in a manner qualitatively similar to its effect in other species. The minimal renal effects caused by zomepirac relative to indomethacin in this primate may indicate a therapeutic advantage for zomepirac in man.