Response of Soybean to Heterodera glycines Races 1 and 2 in Different Soil Types

Experiments were conducted for 3 years at four locations and 1 year with six soil types at a common location in North Carolina to determine damage and control-cost functions for Heterodera glycines races 1 and 2 on soybean. In the experiments on native loamy sand and sandy soils, tolerance limits for initial population densities were 0 or very low, whereas in a muck, the tolerance limit was 315 eggs/500 cm³ soil. The aggressive race 2 was more damaging than race 1 in Lakeland sand and Norfolk loamy sand. The crop response was not different between races in the Appling sandy clay loam and Belhaven muck. Soybean yield responses to H. glycines were linear in six soil types in microplots at a common site. The amount of damage varied among these soil types, with lowest yields in the muck because of severe drought stress in this soil. An exponential function adequately described soybean yield response relative to nematode control with increasing rates of aldicarb in Norfolk loamy sand. Treatment with aldicarb in the Lakeland sand decreased the effective egg population of H. glycines but had only a minor effect in the muck.     

Purification and characterization of the Danish (skive) variant of mouse liver alcohol dehydrogenase

The partially inbred Danish (Skive) strain of mice exhibits a form of liver alcohol dehydrogenase (ADH) which differs in electrophoretic mobility from that of all other inbred mouse strains thus far examined, e.g., C57BL/10, DBA/2J, and BALB/c. In order to compare the catalytic and molecular properties of the variant and normal enzyme forms, they were purified to homogeneity by ion-exchange and affinity chromatography. Tryptic peptides of reduced and carboxymethylated subunits of the normal and variant ADH forms were mapped by thin-layer two-dimensional electrophoresis and chromatography and by reversed-phase high-performance liquid chromatography. A unique nonapeptide in the Danish mouse liver ADH which did not appear in enzymes from C57BL/10, DBA/2J, or BALB/c mice was identified by both methods. Amino acid sequencing of this peptide revealed that the Arg residue at position 124, as predicted from the cDNA sequence of ADH in DBA/2J mice, has been replaced by Leu in the Danish variant. The Leu for Arg substitution in the variant form appears to account for its decreased cathodic mobility with electrophoresis in starch gels at pH 7.2. The K _m and V _max of ADH from the Danish strain for three primary alcohols and three aldehydes were similar in value to those of ADH from the C57BL/10, DBA/2J, and BALB/c strains. Based on the X-ray structure of horse liver ADH, position 124 is on the solvent-exposed surface of the catalytic domain. The finding that the kinetic constants are similar for the normal and variant forms is consistent with the observation that this residue is not in the active site and that there is no known role for it in the ADH catalytic mechanism.This work was supported by NIAAA Grant AA-04307.     

Compatability of Metarhizium anisopliae var. anisopliae with chemical pesticides

The effects of various insecticides on the mycelial growth, sporulation and conidial germination of Metarhizium anisopliae var. anisopliae isolate E₉ were studied in the laboratory. Chlorpyrifos was the most toxic organophosphate to mycelial growth and sporulation at all concentrations. Temephos, malathion and leptophos were highly toxic to sporulation while malathion was the most inhibitory to germination. The carbamates, carbofuran, methomyl and oxamyl were moderately toxic to mycelial growth and sporulation while oxamyl had an adverse effect on germination. The pyrethroids (pyrethrin, permethrin and resmethrin) and the insect growth regulators (diflubenzuron and methoprene) were not inhibitory to the various developmental stages of isolate E₉. The chlorinated hydrocarbons (chlordane, lindane and toxaphene) were more deleterious than all other insecticide groups tested. Among the fungicides, benomyl and maneb produced the greatest inhibition.     

柚花头香化学成分的研究(一)

本文首次报道柚花的香气成分。作者利用憎水性树脂XAD-4吸附柚鲜花的头香,并以毛细管气相色谱和毛细管气相色谱-质谱-计算机联用方法研究头香的化学组分,分离鉴定了17个已知化学成分。它们是芳樟醇、β-蒎烯、β-水芹烯、橙花叔醇等。     

A toxic substance produced by Nocardia otitidiscaviarum isolated from cutaneous nocardiosis

During our studies on toxic substances from clinically isolated Nocarida, a new isolate identified as Nocardia otitidiscaviarum from cutaneous nocardiosis was found to produce a toxic substance called HS-6 that had strong in vitro as well as in vivo toxicity. The mouse intraperitoneal LD₅₀ value was 1.25 mg/kg and the ED₅₀ value for L1210 cultured cells was 0.3 ng/ml. The structure of HS-6 was determined and found to belong to the 16-membered macrocyclic group with a molecular formula of C₄₃H₆₈O₁₂. HS-6 also showed activity against pathogenic fungi such as Cryptococcus neoformans.     

The chemical modification of cysteine-69 of rat liver fatty acid-binding protein (FABP): a fluorescence approach to FABP structure and function

Summary Hepatic-FABP was labelled at cysteine-69 with the fluorescent environmentally sensitive reporter group AEDANS. The labelled protein had an emission maximum at 465 nm indicating that cysteine-69 was buried in a non-polar environment. The modified protein was still able to bind ligands such as oleic acid, oleoyl CoA and haem. The affinity of AEDANS-FABP for haem was unaltered as compared with the native protein indicating that cysteine-69 must be remote from the ligand binding site. The binding of oleic acid did not significantly perturb the fluorescence emission spectrum of the fluorescent reporter group suggesting that there are not large conformational changes in the region of cysteine-69 on fatty acid binding. The binding of stoichiometric amounts of oleoyl CoA was accompanied by a small fluorescence enhancement which suggests that fatty acyl CoAs may interact with other regions of the FABP molecule not involved in fatty acid binding.Abbreviations FABP Fatty Acid-Binding Protein - AEDANS 5-[2-(Acetyl)aminoEthyl]Aminonaphthalene-1-Sulphonic Acid - AAEDANS 5-[2-(Iodoacetyl-AminolEthyl] aminonaphthalene-1-Sulphonic Acid - DTNB 5,5Dithiobis-(2-Nitrobenzoic acid)     

Evidence for inhibitory SH groups in the thiol activated K:Cl cotransporter of low K sheep red blood cells

The monofunctional thiol reagents N-ethylmaleimide (NEM) and methyl methanethiosulfonate (MMTS) stimulate ouabain resistant (OR) electroneutral K:Cl cotransport in LK sheep red blood cells at low, but not at high concentrations. Diamide (DM), on the other hand, only stimulates OR K:Cl flux (Lauf, P.K., J. Memb. Biol. 101: 179–188, 1988). The DM stimulated K:Cl cotransport was decreased toward the control value prior to DM stimulation when NEM or MMTS were added, subsequently. The inhibitory effect was dependent on the compound's concentration and exposure time and, in the case of MMTS, was reversed upon addition of dithiothreitol (DTT). The inhibition was more prominent when NEM treatment was performed at pH 8.0 and disappeared at pH 6.0. In contrast the NEM stimulatory effect was most effective when the pH of NEM treatment was 6.0 (Bauer, J. & Lauf, P.K., J. Memb. Biol. 73: 257–261, 1983). The results suggest the existence of additional, however, inhibitory thiol groups in the already thiol-activated K:Cl cotransporter, with a different pKa value and a lower affinity for NEM or MMTS as compared to the stimulatory thiol groups. Like the activating thiols, the inhibitory sulfhydryls appeared to be inaccessible to non-penetrating thiol reagents and hence, must be located deeper within the red cell membrane.     

Models for contact-mediated pattern formation: cells that form parallel arrays

Kinetic continuum models are derived for cells that crawl over a 2D substrate, undergo random reorientation, and turn in response to contact with a neighbor. The integro-partial differential equations account for changes in the distribution of orientations in the population. It is found that behavior depends on parameters such as total mass, random motility, adherence, and sloughing rates, as well as on broad aspects of the contact response. Linear stability analysis, and numerical, and cellular automata simulations reveal that as parameters are varied, a bifurcation leads to loss of stability of a uniform (isotropic) steady state, in favor of an (anisotropic) patterned state in which cells are aligned in parallel arrays.     

Dispersion population models discrete in time and continuous in space

We analyze a discrete-time model of populations that grow and disperse in separate phases. The growth phase is a nonlinear process that allows for the effects of local crowding. The dispersion phase is a linear process that distributes the population throughout its spatial habitat. Our study quantifies the issues of survival and extinction, the existence and stability of nontrivial steady states, and the comparison of various dispersion strategies. Our results show that all of these issues are tied to the global nature of various model parameters. The extreme strategies of staying-in place and going-everywhere-uniformly are compared numerically to diffusion strategies in various contexts. We approach the mathematical analysis of our model from a functional analysis and an operator theory point of view. We use recent results from the theory of positive operators in Banach lattices.     

Histopathology and cell culture characteristics of liver cells from grc − and grc + rats given diethylnitrosamine

The histopathological response and cell culture characteristics of liver cells from the R16 (grc ^–) strain of rats, which carries an MHC-linked deletion, were examined one week after a single intraperitoneal injection of 200 mg/ kg body weight diethylnitrosamine (DEN) and were compared with the response of liver cells from wild type (grc+) rats. The DEN exposure induced hydropicl vacuolar changes in the parenchymal cells and a limited proliferation of oval cells in the periportal areas of the livers of both grc+ and grc rats. Primary culture of collagenase-digested livers consisted of parenchymal, bile ductular and oval-related cells as determined by cell-specific immunohistochemistry. Subpassaged cells from grc+ rats exhibited oval cell ultrastructural morphology, inducible histochemical staining for gammaglutamyl transpeptidase (GGT), and DEN-associated onset of anchorage-independent growth. Primary cultures of liver cells from R16 rats consistently failed to form cell strains upon subpassage.Abbreviations DEN diethylnitrosamine - grc growth and reproduction complex - GGT gamma-glutamyl transpeptidase - MHC major histocompatibility complex