Two New Species of Aphelenchoididae (Nemata) from Declining Red Pines in Maryland

Aphelenchoides resinosi n. sp. and Ektaphelenchus joyceae n. sp. are described and illustrated from red pines of the Allegheny plateau of Maryland, USA. The new species were found in trees infested with Bursaphelenchus xylophilus. Primary diagnostic characters of A. resinosi females are constriction of the head, basal stylet knobs, tong postuterine sac, two incisures in the lateral field, and conical tail four to five anal body widths long with a simple terminal mucro. Diagnostic characters of the males are two pairs of subventral caudal papillae and spicule shape: Primary diagnostic characters of E. joyceae females are a slight constriction of the head, six similar lips, conical tail, and short postuterine sac. Diagnostic characters of the males are spicule size and shape, a single row of spermatocytes, and one pair of caudal papillae. Within-tree distributions of A. resinosi and E. joyceae are presented. A total of 70% of both red-needled and chlorotic-needled trees in the study were positive for A. resinosi and E. joyceae. Branch hierarchy was related to the percentage of samples positive for A. resinosi.     

Methanogenic Conversion of 3-S-Methylmercaptopropionate to 3-Mercaptopropionate

Anaerobic metabolism of dimethylsulfoniopropionate, an osmolyte of marine algae, in anoxic intertidal sediments involves either cleavage to dimethylsulfide or demethylation to 3-S-methylmercaptopropionate (MMPA) and subsequently to 3-mercaptopropionate. The methanogenic archaea Methanosarcina sp. strain MTP4 (DSM 6636), Methanosarcina acetivorans DSM 2834, and Methanosarcina (Methanolobus) siciliae DSM 3028 were found to use MMPA as a growth substrate and to convert it stoichiometrically to 3-mercaptopropionate. Approximately 0.75 mol of methane was formed per mol of MMPA degraded; methanethiol was not detected as an intermediate. Eight other methanogenic strains did not carry out this conversion. We also studied the conversion of MMPA in anoxic marine sediment slurries. Addition of MMPA (500 (mu)M) resulted in the production of methanethiol which was subsequently converted to methane (417 (mu)M). In the presence of the antibiotics ampicillin, vancomycin, and kanamycin (20 (mu)g/ml each), 275 (mu)M methane was formed from 380 (mu)M MMPA; no methanethiol was formed during these incubations. Only methanethiol was formed from MMPA when 2-bromoethanesulfonate (25 mM) was added to a sediment suspension. These results indicate that in natural environments MMPA could be directly or indirectly a substrate for methanogenic archaea.     

Implications ofrbcL sequence data for higher order relationships of theLoasaceae and the anomalous aquatic plantHydrostachys (Hydrostachyaceae)

Subclass and ordinal relationships ofLoasaceae, a small predominately New World family, are examined usingrbcL sequence data. Sequences were examined for eight of the fifteen genera of theLoasaceae and the morphologically anomalous aquatic genusHydrostachys (Hydrostachyaceae). Parsimony analyses of these sequences, combined with previously publishedrcbL data, indicate thatLoasaceae belong in theCornales, and are the sister group ofHydrangeaceae. This agrees with phylogenies based on chloroplast DNA inverted repeat restriction site, morphological and chemical data. TherbcL trees support the monophyly of theLoasaceae and most generic relationships correspond to current subfamily divisions. TherbcL phylogeny also provides the first suggestion thatHydrostachys is allied with theHydrangeaceae in theCornales.     

Effects of dispersal in a tri-trophic metapopulation model

The aim of this paper is to understand how dispersal in a patchy environment influences the stability properties of tri-trophic metapopulations. Differential equation models for tri-trophic metapopulations are formulated and analysed. The patchy nature of the metapopulations is incorporated through dispersal phases. Two variants are studied: one with a dispersal phase for the top and one with a dispersal phase for the middle level. A complete characterisation of stable and unstable equilibria is given and the possibility of invasion in these food chains is studied. A dispersal phase for the middle level can destabilize the bottom level-middle level interaction, because of the delay that dispersal causes in the reaction to the resource. When the middle level is not efficiently controlled by the top level, the unstable bottom level-middle level pair can destabilize the entire food chain. Dispersal for the top level can destabilize in the same way. A characterisation of the long term behaviour of the models is given. Bistability with a stable three species equilibrium and a stable limit cycle is one of the possibilities.     

Enzymatic conversion of bilirubin monoglucuronide to diglucuronide by rat liver plasma membranes.

Formation of bilirubin monoglucuronide from unconjugated bilirubin requires a microsomal enzyme, UDP-glucuronate glucuronyltransferase (EC 2.4.1.17). Conversion of bilirubin monoglucuronide to bilirubin diglucuronide, the major bilirubin conjugate in bile, was studied in subcellular fractions of rat liver. The highest specific activity for bilirubin diglucuronide formation occurred in a fraction highly enriched in plasma membranes. Studies of reaction stoichiometry and utilization of UDP-D-[14C]glucuronic acid revealed that conversion of bilirubin monoglucuronide to bilirubin diglucuronide is not catalyzed by UDP-glucuronyltransferase, and results from transglucuronidation of bilirubin monoglucuronide, with formation of bilirubin diglucuronide and unconjugated bilirubin. When unconjugated bilirubin was infused intravenously into rats at rates exceeding the maximal hepatic excretory capacity, bilirubin monoglucuronide accumulated in serum and bilirubin diglucuronide was found exclusively in bile as the predominant bilirubin metabolite. These results suggest that formation of bilirubin diglucuronide occurs at the surface membrane of the liver cell. Conversion of bilirubin monoglucuronide to bilirubin diglucuronide may play a role in the transport of bilirubin glucuronides from liver to bile.     

Calcitonin and secretin inhibit bombesin-stimulated serum gastrin and gastric acid secretion in man

The effect of intravenously administered calcitonin and secretin on bombesin-stimulated serum gastrin and gastric acid secretion was studied in 7 volunteers. Secretin G.I.H. (1 C.U./kg per h) and calcitonin (0.5 I.U./kg per h) significantly ($\text{P < 0.05}$) inhibited the serum gastrin and gastric acid responses to bombesin-14 (90 pmol/kg per h). Inhibition of gastrin release could not fully account for the inhibition of gastric acid secretion.     

Continuous Synthesis of (R)-(+)-Benzaldehydecyanohydrin Using (R)-Oxynitrilase in Lyotropic Liquid Crystals

The possibility of using the enzyme (R)-Oxynitrilase in a biphasic lyotropic liquid crystal/dibutylether system has been demonstrated. This reaction system is applicable for the continuous production of (R)-benzaldehydecyanohydrin in a fixed bed reactor. The optical purity was between 94 and 96% ee and independent of the flow rate. The space time yield was maximal (2650 g/(1*d)) at a flow rate of 1.6 ml/min.