The sporulation-specific penicillin-binding protein 5a from Bacillus subtilis is a DD-carboxypeptidase in vitro

A chemiluminescence method for determining acetylcholinesterase activity is described. It is an adaptation of the chemiluminescence assay of acetylcholine described by Israël & Lesbats [(1981) Neurochem. Int. 3, 81-90; (1981) J. Neurochem. 37, 1475-1483]. The acetylcholinesterase activity is measured by monitoring the increase in light emission produced by the accumulation of choline or by determining the amount of choline generated after a short interval. The assay is rapid and sensitive, and uses the natural substrate of the enzyme. Kinetic data obtained with this procedure for acetylcholinesterase from Torpedo and Electrophorus electric organs were comparable with those obtained by using the method of Ellman, Courtney, Andres & Featherstone [(1961) Biochem. Pharmacol. 7, 88-95]. In addition, it was shown that sodium deoxycholate totally inactivated Torpedo acetylcholinesterase but not the Electrophorus enzyme. Competitive inhibitors of acetylcholinesterase protected the enzyme from inactivation.     

N2-(1-carboxyethyl)methionine. A ''pseudo-opine'' in octopine-type crown-gall tumours.

A novel methionine-containing plasmid-determined compound, N2-(1-carboxyethyl)methionine (NCEM) has been identified in crown-gall tumours induced by octopine-type strains of Agrobacterium tumefaciens. NCEM is probably synthesized by octopine synthase. Cell-free preparations from octopine-type strains of A. tumefaciens can degrade NCEM; however, the bacterium cannot transport the compound into the cell, although these strains can take up and degrade the octopine family of opines.     

Lithium increases turnover of phospholipids in flight muscles of Periplaneta americana L

The effect of prolonged lithium administration on the phospholipid metabolism of flight muscles of the cockroach Periplaneta americana has been studied. Following daily injections of LiCl in a dose of 19.25 mumol LiCl per gram of wet weight [32P]- orthophosphate were injected and its incorporation into the phospholipids was measured 2, 12 and 24 h later. Lithium administration did not change the content of phospholipids but increased the 32P incorporation into phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine and sphingomyeline 1.87, 2.13, 2.02 and 1.87 times, respectively, as compared with the control values. These increases were neither due to an increased permeability of the tissue for inorganic phosphate nor to an increased turnover of gamma-P-ATP. It is concluded that prolonged lithium treatment increases the turnover of all phospholipids in insect flight muscle tissue.     

The time course of biochemical and histological changes following carbon tetrachloride-induced liver damage in rats of both sexes

A detailed analysis is presented of the time changes in the development of liver damage 6, 12, 24, 48 and 72 hours after i.p. administration of carbon tetrachloride [CCl4] in a dose of 0.75 ml, i.e. 1 200 mg/kg body weight to rats of both sexes. The severity of liver damage was assessed from the histological and biochemical changes of AST, ALT, alkaline phosphatase and GMT serum activity. From our experiments it follows that in male rats the level of transaminases increases earlier than in female rats, as early as 6 h after the administration of CCl4, reaching a maximum 12 h later. These changes prevail for a longer time period, the level of transaminases remaining increased even 72 h after CCl4 administration. In female rats the biochemical changes occur later reaching the maximum elevation of AST and ALT 24 h after CCl4 administration. The values slowly return to normal after 48 h, and after 72 h the levels of transaminases are identical with the control group. The above given biochemical results are in good agreement with the histological findings demonstrating a higher regenerative activity in female rats. This finding was also proved by specific liver DNA activity assay.     

Cloning and expression of the Listeria monocytogenes haemolysin in Escherichia coli

Abstract Listeriolysin, an SH-activated haemolysin probably involved in Listeria pathogenicity, has been cloned into the cosmid vector pHC79 and was expressed in Escherichia coli HB101 cells. Chromosomal DNA of Listeria monocytogenes serovar 1/2 was partially digested with Mbo I and ligated to the Bam HI cleaved cosmid. From 2000 recombinant clones examined, 12 (0.6%) produced haemolysin in solid and liquid media. All of them contained chromosome fragments of Listeria of about 40 kb. The cloning of the listeriolysin determinant will lead to a better understanding of the basis of Listeria pathogenicity.     

A new species of the lichen genusDiploschistes from Australia

Diploschistes hensseniae Lumbsch & Elix is described as new to science. It is characterized by its terricolous habitat, perithecioid closed ascomata, relatively small spores, cylindrical asci, and the presence of diploschistesic and orsellinic acids in addition to lecanoric acid. It occurs on soil in arid regions of Australia.     

Vegetation structure and microclimate of three Dutch Calthion palustris communities under different climatic conditions

Three Dutch Calthion palustris communities, situated in different phytogeographic districts which vary in elimatic conditions, are compared with respect to vegetation structure and microclimate. The three Calthion stands which are similar in soil, management and hydrology, differ slightly in total aboveground biomass in the period just before cutting, but there is a larger difference in the biomass contributed by phanerogams, bryophytes and litter. The structure of the Calthion communities varies in vertical distribution of biomass and leaf area (LAI), and growth form and leaf size composition. These differences are interpreted in terms of elimatic differences such as length of growing season, temperature and wind. Profiles of decreasing light intensity within the vegetation canopy are related to the vertical distribution of biomass, LAI and leaf inclination of the various Calthion communities. Temperature and saturation deficit of the air on the different sites show profiles of a similar shape which suggests that in such ecologically comparable plant communities, vegetation structure differs under influence of the macroclimate in such a way that the resulting vegetation canopies modify the microclimate within the vegetation to become homologous.Nomenclature of species follows Heukels-van Ooststroom (1977). Acknowledgement. This study is part of the pfoject on vegetation structure, financially supported by the Foundation for Fundamental Biological Research (BION), of the Dutch Organization for the Advancement of Pure Research (ZWO). Much of the research was carried out at the Division of Geobotany, University of Nijmegen. The authors kindly acknowledge this hospitality. Also the data contributed by B. Aerssens, J. Cortenraad, and S. Troelstra and the typing help of Mrs R. Jaegermann are gratefully acknowledged.     

Headache at high altitude is not related to internal carotid arterial blood velocity

The cause of headache in persons going to high altitude is unknown. Relatively severe hypoxemia in susceptible subjects could induce large increases in cerebral blood flow that then could initiate the headache. Thus we measured noninvasively, by Doppler ultrasound, changes in internal carotid arterial blood velocity (velocity) in 12 subjects in Denver (1,600 m) and repeatedly up to 7 h at a simulated altitude of 4,800 m (barometric pressure = 430 Torr). Six subjects, selected because of prior history of high-altitude headache, developed comparatively severe headache at 4,800 m, and four subjects, without such history, remained well. Two subjects developed moderate headache. Velocity at 4,800 m did not correlate with symptom development, arterial O2 saturation, or end-tidal PCO2. Also, neither velocity nor blood pressure was consistently elevated above the Denver base-line values. During measurements of hypercapnic ventilatory response in Denver, velocity increased linearly with end-tidal PCO2, confirming that our Doppler method could demonstrate an increase. Also, 30 min of isocapnic or poikilocapnic hypoxia caused small increases in velocity (+8 and +6%) during the base-line measurement at low altitude. Although even a small increase in cerebral perfusion could contribute to headache symptoms at high altitude, cerebral blood flow does not appear to play a primary role.     

Passage of uncharged dextrans from blood to lung lymph in awake sheep

To examine how molecular size alone influences the passage of macromolecules from the pulmonary microcirculation into lymph collected from the caudal mediastinal lymph node of the sheep, we infused polydisperse uncharged [3H]dextrans intravenously at a constant rate over a period of 7.5 h in nine awake sheep with lung lymph fistulas. Lymph and plasma were collected during hours 5.5-7.5 of the infusions, and the [3H]dextrans were separated by molecular sieve chromatography into fractions that ranged from 1.6 to 8.4 nm in effective molecular (Stokes-Einstein) radius. Lymph-to-plasma (L/P) ratios for [3H]dextrans were near 1.0 at 1.6-nm radius, decreased with increasing molecular size, and approached zero at radii above 5.0 nm. We confirmed that these L/P ratios represented steady-state values by extending the duration of the infusion to approximately 30 h in two of the nine sheep and finding that the L/P ratios remained unchanged. These results were consistent with molecular sieving through a homoporous membrane with cylindrical pores of 5.0-nm radius. We also found that the L/P ratio for albumin [0.76 +/- 0.13 (SE)] in five of the same sheep was much higher than that for the [3H]dextran fraction of the same effective molecular radius [0.11 +/- 0.02 (SE)]. These results suggest that the movement of macromolecules from the pulmonary microcirculation into pulmonary lymph collected from the caudal mediastinal node of the sheep is influenced by both molecular size and molecular charge and that, compared with uncharged dextrans, the steady-state passage of anionic endogenous proteins from plasma to lymph is enhanced.