Mycolic acid analysis in Nocardia species. The mycolic acid compositions of Nocardia asteroides, N. farcinica, and N. nova.

Mycolic acids from twelve Nocardia species were analyzed for structure using capillary gas chromatography and mass spectrometry. This high-resolution procedure permitted good separation of the trimethylsilyl (TMS) ether derivatives of mycolic acid methyl ester according to the total number of carbon and double bonds. The profiles of the mycolic acid molecular species were used as models to illustrate the difference in the structures of each species, even in the case of N. asteroides complex; N. asteroides, N. farcinica and N. nova. Although N. asteroides and N. farcinica had similar lengths of carbon skeleton, i.e., 51.9-53.7 was the average carbon number (Av.Nc.), they had different compositions of unsaturated acids. Mycolic acids from N. asteroides were composed of abundant saturated acids and less than 1% tetraenoic acids; mycolic acids from N. farcinica were composed of unsaturated acids, which were composed of abundant dienoic acids, 2-12% of tetraenoic acids and a trace of pentaenoic acids. In contrast, Av.Nc. of mycolic acids from N. nova were 55.7-56.3, which were relatively longer than those from N. asteroides or N. farcinica. Regarding the characteristics of the structure of alpha-branch, major components were C16:0 and C18:0 for N. asteroides 23206T, and C16:0 and C14:0 for N. farcinica 23157T, respectively. The presence of monounsaturated alpha-branch (C18:1 and C16:1) was characteristic of N. nova.     

Effects of temperature, irradiance, and daylength on the marine diatom Leptocylindrus danicus Cleve. IV. Growth

Growth and dark respiration rates of the marine diatom Leptocylindrus danicus Cleve were measured in axenic batch culture under 49 combinations of temperature (5, 10, 15, 20°C), daylength(15:9, 12:12, 9:15 LD), and irradiance (at least four irradiances per daylength). Cell division rates exhibited a temperature-dependent daylength effect. Optimal temperatures occurred between 15 and 20°C. Both the initial slope () and the growth rate at light saturation (μ_max) were strongly influenced by temperature; increased five-fold and μ_max by an order of magnitude between 5 and 20°C. The compensation irradiance (I_c) was independent of temperature. μ_max was 2.7 div day⁻¹ at 20°C, 2.6 at 15°C, 1.1 at 10°C, and 0.3 at 5 °C. Cells grown under 15:9 and 12:12 LD exhibited similar growth-light curves at 20°C and at 15°C. μ_max of cells grown under 9:15 LD at these temperatures were substantially lower than μ_max under longer daylengths. Growth at 10 and 5°C was independent of daylength.

Dark respiration rates were a linear function of cell division rates at 10, 15, and 20°C, and support the concept that growth rate is dependent on dark respiration rate. These relationships were not influenced by daylength. A detectable relationship between dark respiration and growth at 5°C was not observed.

Photosynthesis and excretion showed temperature-dependent curvilinear relationships with growth rate, reflecting the lower saturation irradiance for growth compared to light saturation of photosynthesis and excretion. The relationship between Chl a-specific photosynthesis and growth was controlled by the C:Chl a ratio, which showed a positive correlation with cell division rate. At 15 and 20°C, light saturation of growth was associated with C:Chl a ratios of 40 to 60; at 5 and 10°C, cells growing at μ_max contained C:Chl a in ratios of 80 to 110.     

O-acetylated gangliosides in bovine buttermilk. Characterization of 7-O-acetyl, 9-O-acetyl, and 7,9-di-O-acetyl GD3.

Three O-acetylated gangliosides, G1, G2, and G3, were purified from bovine buttermilk by using chloroform/methanol extraction, Folch partitioning, chromatography on DEAE-Sephadex A-25, and Iatrobeads columns. The final yields of gangliosides G1, G2, and G3 were 2 mg, 37 mg, and 40 mg per 1.7 kg of the buttermilk powder, respectively. On the basis of immunostaining on high performance thin layer chromatography with specific monoclonal antibodies, mild alkaline treatment, gas-liquid chromatographic analysis, fast atom bombardment mass spectrometry, and proton nuclear magnetic resonance studies, G1 and G2 are characterized as O-acetylated GD3 and G3 as O-acetylated GT3, and the structures of these gangliosides are as follows: [formula: see text] The major fatty acids of these gangliosides were C18:0, C22:0, C23:0, and C24:0, and the long chain base was C18-sphingosine.     

Production of bacteriocin-like substances byYersinia frederiksenii,Y. kristensenii,andY. intermedia strains

The production of bacteriocin-like substances by strains of Yersinia frederiksenii, Y. kristensenii and Y. intermedia in broth culture was established. These substances showed a selective activity against Y. enterocolitica, Y. frederiksenii, Y. kristensenii and Y. intermedia strains. Electron micrographs revealed the presence of phage tails in culture media. The production of these substances was detected in cultures grown at 25 degrees C but not in those grown at 37 degrees C, while these bacteriocin-like substances were active at 25 and 37 degrees C. Y. enterocolitica serogroups 0:3 and 0:9 were more susceptible to these bacterin-like substances than strains of Yersinia isolated from environmental sources.     

Analysis of morphological characters of Chara baltica, C. hispida, C. horrida, and C. rudis from Europe

Morphological characters of Chara baltica, C. hispida, C. horrida, and C. rudis from different localities in Central Europe and Scandinavia were analyzed. The plants were preliminarily classified using specific qualitative features into four species: C. baltica, C. hispida, C. horrida, and C. rudis. Of the 14 characters, all were used in principal-component and cluster analyses, and 12 were applied in a discriminant analysis. In the discriminant analysis, the most useful characters for distinguishing particular species were selected. The methods (canonical discriminant and canonical analyses) used herein offered good differentiation between brackish water species C. horrida and C. baltica and fresh water species C. hispida and C. rudis. The analysis showed that the two morphologically very similar species C. hispida and C. rudis are only partially distinguished.     

Development of nine polymorphic microsatellite loci in the spined loach, Cobitis taenia, and cross-species amplification in the related species C. elongatoides, C. taurica and C. tanaitica

Nine polymorphic microsatellite loci were developed for the spined loach, Cobitis taenia (Teleostei: Cobitidae). The loci were validated using 50 individuals from a population in Belgium. Moderate to high levels of polymorphism were detected (two to 11 alleles). In addition, most markers amplified successfully in three closely related taxa that are known to hybridize with C. taenia: C. elongatoides, C. taurica and C. tanaitica. Some of the loci are most likely diagnostic among species. These markers will be valuable for the study of the historical and contemporary interactions within C. taenia and the Cobitis species complex.     

Nitrogen limitation and particulate elemental ratios of seston in hypersaline Mono Lake, California, U.S.A.

Particulate elemental ratios (C:N, N:P and C:Chl a) of seston in hypersaline (70–90 g kg^–1) Mono Lake, California, were examined over an 11-year period (1990–2000) which included the onset and persistence of a 5-year period of persistent chemical stratification. Following the onset of meromixis in mid-1995, phytoplankton and dissolved inorganic nitrogen were substantially reduced with the absence of a winter period of holomixis. C:N, N:P and C:Chl a ratios ranged from 5 to 18 mol mol^–1, 2 to 19 mol mol^–1 and 25 to 150 g g^–1, respectively, and had regular seasonal patterns. Deviations from those expected of nutrient-replete phytoplankton indicated strong nutrient limitation in the summer and roughly balanced growth during the winter prior to the onset of meromixis. Following the onset of meromixis, winter ratios were also indicative of modest nutrient limitation. A 3-year trend in C:N and N:P ratios toward more balanced growth beginning in 1998 suggest the impacts of meromixis weakened due to increased upward fluxes of ammonium associated with weakening stratification and entrainment of ammonium-rich monimolimnetic water. A series of nutrient enrichment experiments with natural assemblages of Mono Lake phytoplankton conducted during the onset of a previous episode of meromixis (1982–1986) confirm the nitrogen will limit phytoplankton before phosphorus or other micronutrients. Particulate ratios of a summer natural assemblage of phytoplankton collected under nitrogen-depleted conditions measured initially, following enrichment, and then after return to a nitrogen-depleted condition followed those expected based on Redfield ratios and laboratory studies.     

Effects of temperature,irradiance, and daylength on the marine diatom leptocylindrus danicus cleve. I. Photosynthesis and cellular composition

Rates of ¹⁴C uptake and cellular composition of C, N, and Chl a in the marine diatom Leptocylindrus danicus Cleve were measured in axenic batch culture under 49 combinations of temperature (5, 10, 15, 20 °C), daylength (15: 9, 12: 12, 9: 15 LD), and irradiance (at least four irradiances per daylength). ¹⁴C uptake exhibited a temperature-dependent daylength effect. Similar P-I curves characterized cells grown under 15: 9 and 12: 12 LD; P_max values were 17.2, 11.2, 4.3, and 1.8 pg C. pg Chl a^?1. h^?1 at 20, 15, 10, and 5°C, respectively. Under 9:15 LD at 20 and 15°C, the lightsaturated photosynthetic rate was ≈50% that in cells grown under longer daylengths. ¹⁴C uptake was independent of daylength at 10 and 5°C. The initial slope, a, of cells grown under long daylengths increased by five-fold between 5 and 20 °C. α values of cells grown under 9: 15 LD at 15 and 20 °C were depressed relative to longer daylengths. Chl a was inversely related to irradiance, and increased with temperature from 10 to 20 °C, whereas cell carbon and nitrogen showed a similar temperature dependence but was not influenced by irradiance or daylength. The C : N ratio and cell volume were independent of temperature, irradiance, and daylength. Both the C : Chl a and N : Chl a ratios increased with irradiance by greater amounts at lower temperatures.     

Lipids and fatty acids of a moderately halophilic bacterium, No. 101.

The extractable and bound lipids of a moderately halophilic gram-negative rod, strain No. 101 (wild type) grown in a medium containing 2 M NaC1, were examined. The extractable lipids were separated into at least 8 components by using thin-layer chromatography. The major phospholipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an unidentified phosphoglycolipid in the whole cells, cell envelopes and outer membrane preparations, commonly. Judging from mild alkaline hydrolysis and exzymatic treatment with phospholipase A2, C and D, the unidentified phosphoglycolipid possessing Pi, glycerol, fatty acids and glucose in a molar ratio of 1 : 2 : 2 : 1, appeared likely to be a glucosyl derivative of phosphatidylglycerol. No glucuronic acid containing lipid was detected. The exractable lipid composition varied greatly with the concentrations of NaC1 in the medium and the stages of bacterial growth. The most characteristic phosphoglycolipid in this organism increased up to 25% of the total phospholipids with the addition of 1% glucose in the medium. The major fatty acids of the extractable lipids were C16:0, C16:1, C18:0, C18:1 and cyclopropanoic C17 and C19 acids and these compositions were very similar for each phospholipid. The cyclopropanoic fatty acids predominated as growth proceeded. The fatty acids of the bound lipids comprised a high concentration of 3-hydroxydodecanoic acid. The esterified fatty acids of the lipopolysaccharide molecule seemed to contain a wide variety of hydroxy and non-hydroxy shorter chain fatty acids, while the amide-linked fatty acids consisted almost entirely of 3-hydroxydodecanoic acid.     

Ca2+ dependence of the interactions between protein C, thrombin, and the elastase fragment of thrombomodulin. Analysis by ultracentrifugation.

The two-way and three-way interactions among active-site-blocked bovine thrombin, bovine protein C, and the elastase fragment of rabbit thrombomodulin (elTM) were examined by analytical ultracentrifugation at 23.3 degrees C in 100 mM NaCl, 50 mM Tris (pH 7.65), and 1 mM benzamidine, in the presence of 0 to 5 mM calcium chloride. Thrombin and elTM form a tight (Kd less than 10(-8) M) 1:1 complex in the absence of Ca2+ that weakens with the addition of Ca2+ (Kd approximately 4 microM in 5 mM Ca2+). Without Ca2+, thrombin and protein C form a 1:1 complex (Kd approximately 1 microM) and what appears to be a 1:2 thrombin-protein C complex. The Kd for the 1:1 complex weakens over 100-fold in 5 mM CaCl2. Protein C and elTM form a Ca(2+)-independent 1:1 complex (Kd approximately 80 microM). Nearly identical binding to thrombin and elTM is observed when active-site-blocked activated bovine protein C is substituted for protein C. Thrombin inhibited by diisopropyl fluorophosphate and thrombin inhibited by a tripeptide chloromethyl ketone exhibited identical behavior in binding experiments, suggesting that the accessibility of protein C to the substrate recognition cleft of these two forms of thrombin is nearly equal. Human protein C binds with lower affinity than bovine protein C. Ternary mixtures also were examined. Protein C, elTM, and thrombin form a 1:1:1 complex which dissociates with increasing [Ca2+]. In the absence of Ca2+, protein C binds to the elTM-thrombin complex with an apparent Kd approximately 1 microM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Arctic Gasteromycetes II. Calvatia in Greenland, Svalbard and Iceland

Species of Calvatia (Lycoperdaceae) from arctic and subarctic regions are described. The diagnostic characters in Calvatia are discused with emphasis on strutures of peridium and capillitium and colour of gleba. Ten species are recognized. Three species: C. Candida, C. excipuliformis, C. utriformis are confined to subarctic stations, while seven species have their main distribution in the arctic zones. Three of these are new species: C. connivens, C. horrida, C. septentrionalis , while three other species are redefined after studies of type material: C. arctica, C. bellii and C. turneri. Several specimens studied show characters pointing to a hybrid origin.     

Effects of temperature, irradiance, and daylength on the marine diatom Leptocylindrus danicus Cleve. III. Dark respiration

Oxygen consumption in the dark by the marine diatom Leptocylindrus danicus Cleve was measured in batch culture under 49 combinations of temperature (5, 10, 15, 20°C), daylength (15:9, 12:12, 9:15 LD), and irradiance (at least four irradiances per daylength). Dark respiration was influenced by previous light history and temperature. Elevated respiration rates characterized cells grown under higher irradiances at 10, 15, and 20°C; the effects of previous light history were more evident at higher temperatures. At 5°C, oxygen consumption was unaffected by growth irradiance. The highest respiration rates were measured at 20°C; the Q₁₀ value for dark respiration (5 to 20°C) was 4.0. Daylength affected oxygen consumption at 15 and 20°C. The mean R:P ratio in all experiments was 0.139, with lower ratios at higher temperatures and irradiances, and higher ratios at lower temperatures and irradiances. The R:P ratio was unaffected by daylength. Carbon-specific respiration rates exceeded excretion losses in all experiments except under high irradiances at 5°C. The E:R ratio was smaller at lower irradiances and higher temperatures; daylength effects were not evident.     

Involvement of cysteine residues in catalysis and inhibition of human aldose reductase. Site-directed mutagenesis of Cys-80, -298, and -303.

In order to study the potential role of cysteinyl residues in catalysis and inhibition of human aldose reductase, mutants containing cysteine to serine substitution at positions 80 (ALR2:C80S), 298 (ALR2:C298S), and 303 (ALR2:C303S) were constructed. Mutation of Cys298 resulted in the most profound changes, as ALR2:C298S displayed 4- to 5-fold elevation in K'm(NADPH), K'm(DL-glyceraldehyde), and kcat(DL-glyceraldehyde) relative to wild type aldose reductase as well as a 10-fold higher Ki for the aldose reductase inhibitor sorbinil. Wild type and mutant reductases were equally sensitive to tolrestat, a structurally different reductase inhibitor. Carboxymethylation of the wild type enzyme or the C80S and C303S mutants led to a modest decrease in kcat as well as an increase in K'm(DL-glyceraldehyde) and Ki(sorbinil). These parameters were not significantly changed when ALR2:C298S was subjected to carboxymethylation. Lithium sulfate caused activation of ALR2:WT, C80S, and C303S but did not significantly affect the activity of ALR2:C298S. The differential sensitivity of wild type and mutant reductases to inhibition by sorbinil and tolrestat, before and after carboxymethylation, indicates that these inhibitors bind at different sites. These results suggest that Cys-298 is present near the active site and constitutes a regulatory group which controls the catalytic activity and inhibitor sensitivity of the enzyme.     

Hyperhomocysteinemia, thrombosis and vascular biology.

Epidemiological evidence suggests that hyperhomocysteinemia (HH) is an independent risk factor for arterial thrombotic diseases such as acute myocardial infarction, stroke, peripheral ischemic occlusive disorders as well as venous thromboembolism. This article presents a hypothesis to explain the pathogenesis of increases in plasma homocysteine level and associated increased risk of thrombotic disease. It is based on the data in the literature and results from our laboratory on the impact of folate induced HH in rats. These results include: a) Effects on whole blood coagulation, which is characterized by increased velocity of coagulation, increased firmness of the formed coagulum and prolonged initiation phase of the coagulation; b) Genetic regulation of blood cells, which is characterized by increased platelet activation, impaired fibrinolysis and impaired function of the contact activation pathway of coagulation, and c) Reduced functional activities of single coagulation factors FXII:C, FX:C and FII:C.     

Culicoides responses to 1-octen-3-ol and carbon dioxide in salt marshes near Sea Island, Georgia, U.S.A.

Abstract. The semiochemicals carbon dioxide (CO₂) and l-octen-3-ol (octenol) were evaluated as attractants at several release rates, alone and in combination, for the major coastal species of biting midges in Georgia: Culicoides furens, C.hollensis and C.melleus (Diptera: Ceratopogonidae). The data show that CO₂ is an effective attractant for the females of all three species, but each has a different response pattern. In contrast, octenol was an effective attractant only for C.furens , either alone or in combination with CO₂; octenol had a repellent effect on the other two species. The combination of octenol and C0₂ had a synergistic effect on the collections of C.furens.     

武功山山地草甸不同海拔凋落物-土壤碳、氮、磷含量及其生态化学计量特征

以江西省武功山海拔1500~1900 m山地草甸为研究对象,研究不同海拔凋落物-土壤碳(C)、氮(N)、磷(P)含量及生态化学计量特征,并对其相关性进行分析.结果表明:不同海拔下凋落物C、N、P含量分别为397.5~458.24、11.59~17.12、1.05~2.19 mg·g^-1,凋落物C含量随海拔升高不断减小,凋落物N、P含量随海拔升高先下降后升高.土壤C、N、P含量分别为51.64~80.01、3.30~4.77、0.44~1.09 mg·g^-1,土壤C、N、P含量随海拔升高先增加后降低,土壤全P含量变异较小.不同海拔凋落物C∶N、C∶P、N∶P分别为24.73~40.36、203.65~463.08、7.16~13.80,并随海拔升高先升高后下降.不同海拔土壤C∶N、C∶P、N∶P分别为14.95~16.95、56.87~162.52、3.69~10.58,土壤C∶N随海拔升高没有显著变化,土壤C∶P、N∶P随海拔升高先升高后下降,在海拔1600~1700 m处达到最大.武功山山地草甸凋落物与土壤C、N、P含量随海拔升高的变化规律不同,不同海拔凋落物C、N、P均值,以及C∶N、C∶P和N∶P大于土壤.     

The systematics of clarkia bottae,C. Cylindrica,and a related new species,C. Rostrata

Populations ofClarkia cylindrica andC. bottae were studied in the field and in the garden. Seed from which the garden progenies were grown was collected in the wild. Experimental crosses were made between and within taxa. Fertility and chromosome pairing were observed in the hybrids. A maternal influence on seed set was found in crosses between C.cylindrica andC. bottae. Two taxa are described as new:Clarkia rostrata andC. cylindrica ssp.clavicarpa.     

陕西省森林群落乔灌草叶片和凋落物C、N、P生态化学计量特征

研究陕西省121个森林群落中乔叶、灌叶、草叶和凋落物4个层次的C、N、P化学计量学特征及其变异性,分析了各层次间及其与地理因子间的关系.结果表明： 乔叶C、N含量最高,草叶P含量最高,凋落物C、N、P含量均最低.乔叶、灌叶、草叶和凋落物的C∶N∶P分别为439.4∶14.2∶1、599.2∶13.5∶1、416.5∶13.3∶1、504.8∶15.5∶1,乔叶、灌叶、草叶N∶P值差异不显著,但均与凋落物N∶P值差异显著,表明不同生活型活体植物叶片的N∶P值具有一定的稳定性.与N含量相比,C和P含量在各层次间表现出更好的相关性;C、N、P含量及其比值在草叶与乔叶之间较在灌叶与乔叶之间表现出更好的相关性;凋落物与乔叶和草叶之间C、N、P含量均表现出显著正相关,与灌叶只在P含量之间存在显著正相关.灌叶N、P含量随纬度增加而增加,草叶N、P含量随经度增加而降低,海拔对叶片和凋落物C、N、P含量及其比值的影响较小,只有乔叶N∶P与海拔之间存在显著负相关.各地理因子对草叶的影响大小表现为经度>纬度>海拔,对乔叶、灌叶和凋落物的影响大小表现为纬度>经度>海拔.     

Pex, analytical tools for PDB files. II. H-Pex: noncanonical H-bonds in alpha-helices

We use the H-Pex (Thomas et al., this issue) to analyze the main chain interactions in 131 proteins. In antiparallel beta-sheets, the geometry of the N...O bond is: median N...O distances, 2.9 SA, C==O...N angles at 154 degrees and the C alpha--C==O...H angles are dispersed around 3 degrees. In some instances, the other side of the C==O axis is occupied by a HC alpha. As recently supported by Vargas et al. (J Am Chem Soc 2000;122:4750-4755) C alpha H...O and NH...O could cooperate to sheet stability. In alpha-helices, the main chain C==O interact with the NH of their n + 4 neighbor on one side, and with a C beta H or C gamma H on the other side. The median O...N distance (3.0 A) and C==N angle (147 degrees) suggest a canonical H-bond, but the C alpha--C==O...H dihedral angle invalidates this option, since the hydrogen attacks the oxygen at 122 degrees, i.e., between the sp(2) and pi orbitals. This supports that the H-bond is noncanonical. In many instances, the C gamma H or the C beta H of the n + 4 residue stands opposite to the NH with respect to the oxygen. Therefore, we propose that, in alpha-helices, the C gamma H or C beta H and the NH of the n + 4 residue hold the oxygen like an electrostatic pincher. Proteins 2001;43:37-44.     

Erratum to H. Frederik Nijhout,et al. Epigenetics Volume 1, Issue 2; pp. 81-87.

In the paper, Long-Range Allosteric Interactions between the Folate and Methionine Cycles Stabilize DNA Methylation Reaction Rate, by H. Frederik Nijhout, Michael C. Reed, David F. Anderson, Jonathan C. Mattingly, S. Jill James and Cornelia M. Ulrich (Epigenetics 2006; 2:81-87), an eqution was misprinted on page 86 of the appendix. The corrected equations can be found in the online pdf.