Accumulation of intermediates in a denitrifying process at different copper and high nitrate concentrations

NO2- accumulation occurred in an upflow anaerobic sludge blanket reactor at 500, 1000 and 1500 mg NO3- -N/l, but not after copper in the medium was increased to 28 g Cu2/l. N2O release was not avoided even with 56 g Cu2/l, at 1500 and 2500 mg NO3- -N/l and reached 251 mg N2O-N/ld. © Rapid Science Ltd. 1998     

Cr(VI) increases tyrosine phosphorylation through reactive oxygen species-mediated reactions

While Cr (VI)containing compounds are well established carcinogens, the mechanisms of their action remain to be investigated. In this study we show that Cr (VI) causes increased tyrosine phosphorylation in human lung epithelial A549 cells in a timedependent manner. Nacetylcysteine (NAC), a general antioxidant, inhibited Cr (VI)induced tyrosine phosphorylation. Catalase, a scavenger of H₂O₂, sodium formate and aspirin, scavengers of hydroxyl radical (OH), also inhibited the increased tyrosine phosphorylation induced by Cr (VI). SOD, an inhibitor of superoxide radical (O₂ ^–), caused less inhibition. ESR study shows that incubation of Cr (VI) with the A549 cells generates OH radical. The generation of radical was decreased by addition of catalase and sodium formate, while SOD did not have any inhibitory effect. Oxygen consumption measurements show that addition of f Cr (VI) to A549 cells resulted in enhanced molecular oxygen consumption. These results indicate that Cr (VI) can induce an increase in tyrosine phosphorylation. H₂O₂ and OH radicals generated during the process are responsible for the increased tyrosine phosphorylation induced by Cr (VI).     

Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.     

Stabilization of G•C-Containing DNA Duplexes by Polyamides with Parallel Orientation in the Minor Groove

The polyamides based on 4-amino-1-methylpyrrol-2-carboxylic acid, 4-amino-1-methylimidazole-2-carboxylic acid, and -alanine that stabilize oligonucleotide duplexes consisting of GC pairs through parallel packing in the minor groove were studied. The initial duplex TTGCGCpGCGCAA melts at 28°C; the TTGCGCp[NH(CH₂)₃COPyImImNH(CH₂)₃NH(CH₃)₂][NH(CH₂)₃COImImPyNH(CH₂)₃N(CH₃)₂]GCGCAA duplex (bisphosphoramidate with parallel orientation of ligands, where Py, Im, and are the residues of 1-methyl-4-aminopyrrol-2-carboxylic and 1-methyl-4-aminoimidazole-2-carboxylic acids and -alanine, respectively), at 48°C; and the TTGCGCp[NH(CH₂)₃COImImPyNH(CH₂)₃COImImPyNH(CH₂)₃N(CH₃)₂]GCGCAA duplex (a hairpin structure with antiparallel orientation), at 56°C.     

Activation of immunoglobulin control elements in trasgenic mice

To assess the role interleukins and mitogens play in regulating immunoglobulin (Ig) gene expression via the Ig enhancer and promoter, transgenic mice carrying two different Ig gene regulatory regions were generated. One, EkCAT, contains the Ig heavy chain enhancer (E) and the light chain promoter driving the chloramphenicol acetyltransferase (CAT) gene. In the other, EkCAT, CAT is under the control of the promoter alone. E and relative activity were assessed by CAT assay. In EkCAT mice, low CAT expression was consistently found in spleen, bone marrow, mesenteric lymph node, and thymus but not in brain, lung, or kidney. In EkCAT mice, CAT expression was detectable just above background in lymphoid tissues, suggesting a basic level of tissue specificity in the absence of the enhancer. Whole spleen cell cultures prepared from the mice were treated with lymphokines and mitogens. Lipopolysaccharide (LPS), concanavilin A (Con A), interleukin 6 (IL-6), and interferon- (IFN-) increased CAT expression to varying extents in cells derived from EkCAT mice but not in spleen cells prepared from EkCAT mice. Thus, the presence of E, in addition to the promoter, is essential for the stimulation of CAT expression mediated by these factors. B cells from EkCAT mice were separated by density into populations of small and large cells. In untreated small B cells, no CAT expression was detected and only addition of LPS resulted in an increase in CAT expression. In large B cells, CAT was expressed at a low level without addition of exogenous factors. Incubation with LPS, IL-6, Con A and IFN- caused CAT expression to increase several-fold. This transgenic system provides a means to identify exogenous factors that activate Ig enhancers and promoters.This work has been submitted in partial fulfillment of the requirements for the doctoral degree from the George Washington University.     

Development of an L6 myoblast in vitro model of moniliformin toxicosis

L6 myoblasts were used as an in vitro model to investigate the role of moniliformin and its interaction with monensin in turkey knockdown syndrome and sudden death syndromes in poultry. Cell viability and microscopic and ultrastructural alterations noted in L6 myoblasts cultured in the presence of moniliformin (0.0–0.3 g/l) were compared to those observed in parallel cultures also containing one of the following compounds: selenium (0–0.004 ng/l), thiamine (0–0.3 g/l), or pyruvate (0–0.46 g/l). Marked dilation of the RER, membranous whorls, glycogen deposition, membrane-bound cytoplasmic inclusions and necrosis were observed in myoblasts exposed to 0.03/2-0.30 g moniliformin/l medium. Supplementation of medium with thiamine and pyruvate, or selenium, provided significant protection to cells exposed to 0.0–0.3 g/l or 0.0–0.15 g moniliformin/l, respectively. Dose-dependent differences in protein and ATP production were not detected. Myoblasts grown in medium containing 0–0.15 g moniliformin/l and 7.5–50.0 M A23187, beauvericin or monensin had degrees of cytotoxicity similar to parallel cultures receiving only an ionophore. L6 myoblasts were a useful model of moniliformin toxicosis. The findings of this study suggest cytotoxicity due to moniliformin in L6 myoblasts may be due in part to oxidative damage and altered pyruvate metabolism, and that moniliformin does not predispose myoblasts to ionophore toxicosis. This study supports the results of in vivo investigations in poultry that moniliformin and monensin do not act synergistically to induce knockdown or monensin toxicosis.     

Glycosphingolipid expression in human skeletal and heart muscle assessed by immunostaining thin-layer chromatography

In this study the comparative TLC immunostaining investigation of neutral GSLs and gangliosides from human skeletal and heart muscle is described. A panel of specific polyclonal and monoclonal antibodies as well as the GM1-specific choleragenoid were used for the overlay assays, combined with preceding neuraminidase treatment of gangliosides on TLC plates. This approach proved homologies but also quantitative and qualitative differences in the expression of ganglio-, globo- and neolacto-series neutral GSLs and gangliosides in these two types of striated muscle tissue within the same species. The main neutral GSL in skeletal muscle was LacCer, followed by GbOse3Cer, GbOse4Cer, nLcOse4Cer and monohexosylceramide, whereas in heart muscle GbOse3Cer and GbOse4Cer were the predominant neutral GSLs beside small quantities of LacCer, nLcOse4Cer and monohexosylceramide. No ganglio-series neutral GSLs and no Forssman GSL were found in either muscle tissue. GM3(Neu5Ac) was the major ganglioside, comprising almost 70% in skeletal and about 50% in cardiac muscle total gangliosides. GM2 was found in skeletal muscle only, while GD3 and GM1b-type gangliosides (GM1b and GD1) were undetectable in both tissues. GM1a-core gangliosides (GM1, GD1a, GD1b and GT1b) showed somewhat quantitative differences in each muscle; lactosamine-containing IV3Neu5Ac-nLcOse4Cer was detected in both specimens. Neutral GSLs were identified in TLC runs corresponding to e.g. 0.1 g muscle wet weight (GbOse3Cer, GbOse4Cer), and gangliosides GM3 and GM2 were elucidated in runs which corresponded to 0.2 g muscle tissue. Only 0.02 g and 0.004 g wet weight aliquots were necessary for unequivocal identification of neolacto-type and GM1-core gangliosides, respectively. Muscle is known for the lowest GSL concentration from all vertebrate tissues studied so far. Using the overlay technique, reliable GSL composition could be revealed, even from small muscle probes on a sub-orcinol and sub-resorcinol detection level. Abbreviations: ATCC, American Type Culture Collection; GSL(s), glycosphingolipid(s); HPLC, high performance liquid chromatography; HPTLC, high performance thin layer chromatography; Neu5Ac, N-acetylneuraminic acid; Neu5Gc, N-glycolylneuraminic acid [78]; PBS, phosphate buffered saline. The designation of the following glycosphingolipids follows the IUPAC-IUB recommendations [79] and the ganglioside nomenclature system of Svennerholm [80]. Lactosylceramide or LacCer, Gal1-4Glc1-1Cer; gangliotriaosylceramide or GgOse3Cer, GalNAc1-4Gal1-4Glc1-1Cer; gangliotetraosylceramide or GgOse4Cer, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; globotriaosylceramide or GbOse3Cer, Gal1-4Gal1-4Glc1-1Cer; globoside or globotetraosylceramide or GbOse4Cer, GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; Fo or Forssman GSL, GalNAc1-3GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; paragloboside or lacto-N-neotetraosylceramide or nLcOse4Cer, Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; lacto-N-norhexaosylceramide or nLcOse6Cer, Gal1-4GlcNAc1-3Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; GM3, II3Neu5Ac-LacCer; GM2, II3Neu5Ac-GgOse3Cer; GM1 or GM1a, II3Neu5Ac-GgOse4Cer; GM1b, IV3Neu5Ac-GgOse4Cer; GD3, II3(Neu5Ac)2-LacCer; GD1a, IV3Neu5Ac,II3Neu5Ac-GgOse4Cer; GD1b, (II3Neu5Ac)2-GgOse4Cer; GD1, IV3Neu5Ac,III6Neu5Ac-GgOse4Cer; GT1b, IV3Neu5Ac,II3(Neu5Ac)2-GgOse4Cer; GQ1b, IV3(Neu5Ac)2, II3(Neu5Ac)2-GgOse4Cer.     

Corticosteroid-binding globulin synthesis and distribution in rat white adipose tissue

The lactone isolated from Fusarium termed L659,699 is a potent specific inhibitor of the enzyme 3hydroxi3methylglutaril coenzyme A (HMG-CoA) synthase. In cultures of smooth muscle cells (SMC) isolated from aortic-arch of control (CSMC) and 5% of cholesterol diet (Ch-SMC) treated chicks, the incorporation of (¹⁴C)acetate to lipids (cholesterol, triacylglycerides and cholesterol ester) were greater in ChSMC cultures than in CSMC and the presence of 0.05 M L659,699 for 2 h in the incubation medium decrease the synthesis of cholesterol however the triacylglycerides synthesis increase. The effect of inhibitor is stronger in young cultures (3–4 steps) than in the older ones (11–12 steps). In young CSMC and ChSMC cultures the inhibition of cholesterol and triacylglycerides synthesis by L659,699 was reversal.     

The effect of monoterpenes on astaxanthin production by a mutant ofPhaffia rhodozyma

Summary The total pigment and astaxanthin content ofPhaffia rhodozyma increased with increasing concentrations -pinene up to 500 l -pinene/l. Above this concentration the total pigment and astaxanthin content as well as the biomass production decreased. The addition of 500 l -pinene/l increased the total pigment content from 1652 g/g to 2201 g/g and the astaxanthin content from 1554 g/g to 1883 g/g. A sharp decrease in maximum specific growth rate occurred above 150 l -pinene/l.     

A new enzymatic route to the synthesis of 12-ketoursodeoxycholic acid

Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively.     

The Solution Structure of [d(CGC)r(amamam)d(TTTGCG)]2

The solution structure and hydration of a DNARNA hybrid chimeric duplex [d(CGC)r(a_ma_ma_m)d(TTTGCG)]₂ in which the RNA adenines were substituted by 2-O-methylated riboadenines was determined using two-dimensional NMR, simulated annealing, and restrained molecular dynamics. Only DNA residue 7T in the 2-OMe-RNA DNA junction adopted an O4-endo sugar conformation, while the other DNA residues including 3C in the DNA 2-OMe-RNA junction, adopted C1-exo or C2-endo conformations. The observed NOE intensity of 2-O-methyl group to H1 proton of 4a_m at the DNA 2-OMe-RNA junction is much weaker than those of 5a_m and 6a_m. The 2-O-methyl group of 4a_m was found to orient towards the minor groove in the trans domain while the 2-O- methyl groups of 5a_m and 6a_m were found to be in the gauche (+) domain. In contrast to the long-lived water molecules found close to the RNA adenine H2 and H1 protons and the methyl group of 7T in the RNA-DNA junction of [d(CGC)r(aaa)d(TTTGCG)]₂, there were no long-lived water molecules found in [d(CGC)r(a_ma_ma_m)d(TTTGCG)]₂. This is probably due to the hydrophobic enviroment created by the 2-O-methylated riboadenines in the minor groove or due to the wider minor groove width in the middle of the structure. In addition, the 2-O-methylation of riboadenines in pure chimeric duplex increses its melting temperature from 48.5°C to 51.9°C. The characteristic structural features and hydration patterns of this chimeric duplex provide a molecular basis for further therapeutic applications of DNARNA hybrid and chimeric duplexes with 2-modified RNA residues.     

Immobilized Lotus tetragonolobus agglutinin binds oligosaccharides containing the Lex determinant

A defined set of oligosaccharides and glycopeptides containing -linked fucose were used to examine the specificity of the immobilized fucose-binding lectin Lotus tetragonolobus agglutinin (LTA1), also known as lotus lectin. Glycans containing the Lewis x determinant (Lex) Gal1-4[Fuc1-3]GlcNAc1-3-R were significantly retarded in elution from high density LTA-Emphaze columns. The lectin also bound the fucosylated lacdiNAc trisaccharide GalNAc1-4[Fuc1-3]GlcNAc. The lectin did not bind glycans containing either sialylLex or VIM-2 determinants, nor did it bind the isomeric Lea, Gal1-3[Fuc1-4]GlcNAc-R. Although 2-fucosyllactose Fuc1-2Gal1-4Glc) was retarded in elution from the columns, larger glycans containing the H-antigen Fuc1-2Gal1-3(4)GlcNAc-R interacted poorly with immobilized LTA. Our results demonstrate that immobilized LTA is effective in isolating glycans containing the Lex antigen and is useful in analyzing specific fucosylation of glycoconjugates. Abbreviations: LTA, Lotus tetragonolobus agglutinin; UEA-1, Ulex europaeus agglutinin-I; LNT, AAL, Aleuria aurantia agglutinin; Gal1-3GlcNAc1-3Gal1-3Glc; LNnT, Gal1-4GlcNAc1-3Gal1-3Glc; Lex, Lewis x antigen; Lea, Lewis a antigen; GDPFuc, guanosine 5-diphosphate--L-fucose     

Concluding remarks

On the basis of symposium contributions onChlorella, Hibbertia, Eucalyptus, Ambrosia and on numerical approaches some fundamental problems of (bio)systematics, evolution, and taxonomic categories are discussed: Methods available for analysing affinities; conflicting evidence from phenetic, biochemical, cytogenetic and other analyses; further classification problems in cases of intermediacy, etc. While sibs of various levels and their natural hierarchy often can be objectively defined, this appears impossible for particular taxonomic levels itself (e. g. species). A single objective taxonomic system of organisms is unrealistic. Certain guiding lines for relative and practicable concepts of species and genus are proposed.Presented at the symposium Speciation and the Species Concept during the XIIth International Botanical Congress, Leningrad, July 8, 1975.     

Quantitation of movement of the phosphoryl group during catalytic transfer in the arginine kinase reaction: 31P relaxation measurements on enzyme-bound equilibrium mixtures

³¹P nuclear spin relaxation measurements have been made on enzyme-bound equilibrium mixtures of lobster-muscle arginine kinase in the presence of substituent activating paramagnetic cation Co(II) (in place of Mg(II)), i.e., on samples in which the reaction, ECoATParginine ECoADPP-arginine, is in progress. The results have been analyzed on the basis of a previously published theory (Nageswara Rao, B.D. (1995) J. Magn. Reson., B108, 289–293) to determine the structural changes in the reaction complex accompanying phosphoryl transfer. The analysis enables the determination of the change in the Co(II)-³¹P (-P(ATP)) vector as the transferable phosphoryl group moves over and attaches to arginine to form P-arginine. It is shown that the Co(II)-³¹P distance of 3.0 Å, representing direct coordination of Co(II) to -P(ATP), changes to 4.0 Å when P-arginine is formed in the enzyme-bound reaction complex. This elongation of the Co(II)-³¹P vector implies an excursion of at least 1.0 Å for the itinerant phosphoryl group on the surface of the enzyme.     

Generation of reactive oxygen species in the enzymatic reduction of PbCrO4 and related DNA damage

Free radical reactions are believed to play an important role in the mechanism of Cr(VI)-induced carcinogenesis. Most studies concerning the role of free radical reactions have been limited to soluble Cr(VI). Various studies have shown that solubility is an important factor contributing to the carcinogenic potential of Cr(VI) compounds. Here, we report that reduction of insoluble PbCrO₄ by glutathione reductase in the presence of NADPH as a cofactor generated hydroxyl radicals (OH) and caused DNA damage. The OH radicals were detected by electron spin resonance (ESR) using 5,5-dimethyl-N-oxide as a spin trap. Addition of catalase, a specific H₂O₂ scavenger, inhibited the OH radical generation, indicating the involvement of H₂O₂ in the mechanism of Cr(VI)-induced OH generation. Catalase reduced OH radicals measured by electron spin resonance and reduced DNA strand breaks, indicating OH radicals are involved in the damage measured. The H₂O₂ formation was measured by change in fluorescence of scopoletin in the presence of horseradish peroxidase. Molecular oxygen was used in the system as measured by oxygen consumption assay. Chelation of PbCrO₄ impaired the generation of OH radical. The results obtained from this study show that reduction of insoluble PbCrO₄ by glutathione reductase/NADPH generates OH radicals. The mechanism of OH generation involves reduction of molecular oxygen to H₂O₂, which generates OH radicals through a Fenton-like reaction. The OH radicals generated by PbCrO₄ caused DNA strand breakage.     

Pancreatic glucagon cells contain endorphin-like immunoreactivity

Summary On the basis of the histochemical activity of succinic dehydrogenase, only two fibre-types are distinguished in pigeon pectoralis major muscle. These are narrow Red and broad White. The histochemical activity of myofibrillar ATPase was studied in these two distinct fibre-types. Both fibre-types showed high activity for the ATPase. Red fibres of pigeon pectoralis were not alkali-labile, at incubation pH 9.4, as were the Type I fibres of both avian and mammalian muscles. Again unlike Type I fibres, the Red fibres of pigeon pectoralis lacked the characteristic activation of acid-preincubated ATPase reaction. Pigeon pectoralis Red fibres are known to posses some characteristics of fast-twitch fibres (e.g. high fat, considerable phosphorylase, fibrillenstruktur myofibrillar arrangement, focal en plaque pattern of nerve endings). It is emphasized, therefore, that the pigeon pectoralis Red fibres are not equivalent to Type I or slow-twitch, muscle fibres, but they are possibly fast-twitch fatigue resistent or Type II Red muscle fibres.     

The human genes for the α and γ subunits of the mast cell receptor for immunoglobulin E are located on human chromosome band 1823

The receptor with high affinity for immunoglobulin E (FcERI) is a key molecule in triggering the allergic reaction. It is tetrameric complex of one subunit, one subunit, and two disulfide-linked subunits. This receptor is present exclusively on mast cells and basophils. Molecules identical to the subunit of FcRI also form cell surface complex with other Fc receptors such as mouse FcRIIa in macrophages and most probably with human FcRIII (CD16) in natural killer (NK) cells. Here we show by in situ hybridization that the human genes for the (FCER1A) and subunits (FCER1 G) of FcERI and the gene for FcRIII (FCGR3, CD16) are located on human chromosome band 1823.     

Photosynthetic oxygen evolution: H/D isotope effects and the coupling between electron and proton transfer during the redox reactions at the oxidizing side of Photosystem II

The oxygen evolving complex (OEC) of Photosystem II (PS II) incorporates a Mn-cluster and probably a further redox cofactor, X. Four quanta of light drive the OEC through the increasingly oxidized states S0 S1 S2 S3 S4 to yield O2 during the transition S4 S0. It has been speculated that the oxidation of water might be kinetically facilitated by the abstraction of hydrogen. This implied that the respective electron acceptor is deprotonated upon oxidation. Whether YZ and X fulfill this expectation is under debate. We have previously inferred a 'chemical' deprotonation of X based on the kinetics of proton release (Haumann M, Drerenstedt W, Hundelt M and Junge W (1996) Biochim Biophys Acta 1273: 237–250. Here, we investigated the rates of electron transfer and proton release as function of the D2O/H2O ratio, the pH, and the temperature both in thylakoids and PS II core particles. The largest kinetic isotope effect on the rate of electron transfer (factor of 2.1–2.4) and the largest pH-dependence (factor of about 2 between pH 5 and 8) was found on S2 S3 where X is oxidized. During the other transitions both factors were much smaller ( 1.4). Electron transfer is probably kinetically steered by proton transfer only during S2 S3. These results corroborate the notion that X serves as a hydrogen acceptor for bound water during S4 S0. We propose a consistent scheme for the final reaction with water to yield dioxygen: two two-electron (hydrogen) transfers in series with a peroxide intermediate.     

Mutants of Arabidopsis thaliana with altered phototropism

Thirty five strains of Arabidopsis thaliana (L.) Heynh. have been identified with altered phototropic responses to 450-nm light. Four of these mutants have been more thoroughly characterized. Strain JK224 shows normal gravitropism and second positive phototropism. However, while the amplitude for first positive phototropism is the same as that in the wild-type, the threshold and fluence for the maximum response in first positive phototropism are shifted to higher fluence by a factor of 20–30. This mutant may represent an alteration in the photoreceptor pigment for phototropism. Strain JK218 exhibits no curvature to light at any fluence from 1 mol·m^-2 to 2700 mol·m^-2, but shows normal gravitropism. Strain JK345 shows no first positive phototropism, and reduced gravitropism and second positive phototropism. Strain JK229 shows no measurable first positive phototropism, but normal gravitropism and second positive phototropism. Based on these data, it is suggested that: 1. gravitropism and phototropism contain at least one common element; 2. first positive and second positive phototropism contain at least one common element; and 3. first positive phototropism can be substantially altered without any apparent alteration of second positive phototropism.Abbreviation WT wild-type     

Functionally associated molecular genetic marker map construction in perennial ryegrass (Lolium perenne L.)

A molecular marker-based map of perennial ryegrass (Lolium perenne L.) has been constructed through the use of polymorphisms associated with expressed sequence tags (ESTs). A pair-cross between genotypes from a North African ecotype and the cultivar Aurora was used to generate a two-way pseudo-testcross population. A selection of 157 cDNAs assigned to eight different functional categories associated with agronomically important biological processes was used to detect polymorphic ESTRFLP loci in the F₁(NA₆ í AU₆) population. A comprehensive set of ESTSSR markers was developed from the analysis of 14,767 unigenes, with 310 primer pairs showing efficient amplification and detecting 113 polymorphic loci. Two parental genetic maps were produced: the NA₆ genetic map contains 88 ESTRFLP and 71 ESTSSR loci with a total map length of 963 cM, while the AU₆ genetic map contains 67 ESTRFLP and 58 ESTSSR loci with a total map length of 757 cM. Bridging loci permitted the alignment of homologous chromosomes between the parental maps, and a sub-set of genomic DNA-derived SSRs was used to relate linkage groups to the perennial ryegrass reference map. Regions of segregation distortion were identified, in some instances in common with other perennial ryegrass maps. The EST-derived marker-based map provides the basis for in silico comparative genetic mapping, as well as the evaluation of co-location between QTLs and functionally associated genetic loci.An erratum to this article can be found at M.J. Faville and A.C. Vecchies contributed equally to this work.