5′-Nucleotidase

Summary To get more insight in the function of 5-nucleotidase catabolic and anabholic processes were investigated in which 5-nucleotides are involved. The catabolism of adenosine-5-monophosphate was studied by investigating the reaction products obtained after incubation of homogenates of several organs of rat and mouse with adenosine-5-monophosphate and with adenosine. Two experimental tumours of the mouse were investigated in the same way. It was found that in tissues containing a high activity of 5-nucleotidase other enzymes involved in the catabolism of 5-nucleotides, such as nucleosidase, adenosine deaminase and adenosine-5-monophosphate deaminase could also be demonstrated.The anabolic processes in which 5-nucleotides are involved had been studied by investigating the incorporation of tritium-labeled thymidine in several tissues of the mouse. It appeared that in cells showing a high 5-nucleotidase activity no incorporation of radioactive thymidine could be found, while in cells showing incorporation of thymidine enzyme activity could not be demonstrated.A discussion is given about the possible role of 5-nucleotidase in the control of nucleic acid biosynthesis and in the catabolism of nucleic acids.Abbreviations used DNA deoxyribonucleic acid - RNA ribonucleic acid - AMP Adenosine-5-monophosphate - ADP Adenosine-5-diphosphate - ATP Adenosine-5-triphosphate - IMP Inosine-5-monophosphate - GMP Guanosine-5-monophosphate - GDP Guanosine-5-diphosphate - GTP guanosine-5-triphosphate - CMP Cytidine-5-monophosphate - CDP Cytidine-5-diphosphate - CTP Cytidine-5-triphosphate - UMP Uridine-5-monophosphate - UDP Uridine-5-diphosphate - UTP Uridine-5-triphosphate - TMP Thymidine-5-monophosphate - TDP Thymidine-5-diphosphate - TTP Thymidine-5-triphosphate - Ado Adenosine - Ad Adenine - Ino Inosine - Hypox Hypoxanthine - Xanth Xanthine - Xantho Xanthosine - Guano Guanosine - Gua Guanine - Ura Uracil - U Uridine - Cyt Cytidine - Cyto Cytosine - Thym Thymidine The corresponding deoxy-compounds have been indicated with the prefix d for instance dCMP, deoxycytidine-5-monophosphate.     

Inheritance of mitochondrial DNA in lentil (Lens culinaris Medik.)

Restriction fragment analysis was used to examine the inheritance of lentil mitochondrial DNA (mtDNA) in F₁ and F₅ progeny from intrasubspecific (Lens culinaris ssp. culinaris) crosses and in F₁ progeny from intersubspecific (Lens culinaris ssp. orientalis x L. culinaris ssp. culinaris) crosses. Southern blots of digested parental and progeny DNA were hybridized to heterologous maize mtDNA probes specific to coxI and atp6 genes. Two restriction fragment polymorphisms separated L.c. ssp. culinaris Laird and Eston from L.c. ssp. culinaris ILL5588, and one restriction fragment polymorphism distinguished L.c. ssp. culinaris Laird and Eston from L.c. ssp. orientalis LO4. Twelve of 13 f₁ progeny and all F₅ progeny from the intrasubspecific crosses, and all F₁ progeny from intersubspecific crosses had only maternal mtDNA restriction fragments. One f₁ plant from an Eston x ILL5588 cross inherited mtDNA fragments from both parents. Nuclear DNA inheritance was biparental in all F₁ progeny.NRCC No. 38451     

Sources and inheritance of resistance to leaf curl virus in Lycopersicon

Summary One hundred and twenty-two varieties, lines and wild accessions of Lycopersicon were screened under three different regimes during the autumn/winter season of 1982–83 and 1983–84 for resistance to tomato leaf curl virus (TLCV). L. hirsutum f. glabratum (B6013) and L. hirsutum f. typicum (A1904) proved to be highly resistant to TLCV in all three environments. Various accessions of L. peruvianum were also highly resistant. L. pimpinellifolium (A1921) exhibited no TLCV symptoms within 90 days. Of the cultivated varieties, Acc 99 exhibited the minimim score for susceptibility; AC 142, Collection No. 2, Kalyanpur Angurlata and HS 101 had a low rating for virus incidence. The inheritance of resistance was studied in the interspecific crosses between a TLCV resistant line of L. pimpinellifolium (A1921) and five (HS 101, HS 102, HS 110, Pusa Ruby and Punjab Chhuhara) susceptible cultivars of L. esculentum. Parents, F₁, F₂ and backcross progenies were artificially inoculated with local strains of TLCV using vector the viruliferious whitefly, Bemisia tabaci (Genn.). Data indicated that the resistance of L. pimpinellifolium (A 1921) is monogenic and incompletely dominant over susceptibility.     

Basis of the Relationship between Ash Content in the Flag Leaf and Carbon Isotope Discrimination in Kernels of Durum Wheat

The relationship between ash content and carbon isotope discrimination () was studied in durum wheat (Triticum durum Desf.) grown in a Mediterranean region (Northwest Syria) under three different water regimes (hereafter referred to as environments). In two of these environments, 144 genotypes were cultivated under rain-fed conditions. In the third environment, 125 genotypes were cultivated under irrigation. Ash content was measured in the flag leaf about 3 weeks after anthesis, whereas was analysed in mature kernels. Total transpiration of the photosynthetic tissues of the culm contributing, from heading to maturity, to the filling of kernels was also estimated. Leaf ash content, expressed either on dry matter or leaf area basis or as total ash per blade, correlated positively (p< 0.001) with in the three environments. However, this relationship was not the result of a positive correlation across genotypes between and tissue water content. Moreover, only a small part of the variation in across genotypes was explained by concomitant changes in ash content. When all genotypes across the three environments were plotted, and ash content followed a non-linear relationship (r ² = 74), with tending to a plateau as the ash content increased. However, for the set of genotypes and environments combined, total ash content per leaf blade was positively and linearly related (r ² = 0.76) with the accumulated culm transpiration. The non-linear nature of the relationship between ash content and is sustained by the fact that culm transpiration also showed a non-linear relationship with kernel . Therefore, differences in leaf ash content between environments, and to a lesser extent between genotypes, seem to be brought about by variations in accumulated transpiration during grain formation.     

Photoperiodism and thermoperiodism in the predatory mite Amblyseius potentillae are probably based on the same mechanism

Summary A comparative study was made of the photoperiodic and thermoperiodic induction of diapause in the phytoseiid mite Amblyseius potentillae. Sensitivity to thermoperiod was found to be highest during the protonymphal and deutonymphal stages, with some sensitivity still being present in the young adult. Summation of both photoperiodic and thermoperiodic cycles was shown to take place, which demonstrated the presence of a photoperiodic counter as well as a thermoperiodic counter in these mites. Vitamin A appeared to be necessary for some early step in the physiological mechanism of diapause induction and not just for the expression of the diapause response. The light sensitivity threshold for photoperiodic induction of diapause was found to be extremely low, viz. less than 0.02 W/cm². Moreover, the light sensitivity threshold appeared to be strongly temperature dependent in A. potentillae. Experiments in which the mites experienced various sequences of short-day photoperiods and short-day thermoperiods, applied either concurrently or in succession, showed that the information collected by the photoperiodic counter and the thermoperiodic counter is integrated into one induction sum. These results strongly suggest that photoperiodic and thermoperiodic induction of diapause in these mites is based on the same physiological mechanism.Abbreviations DD continuous darkness - LL continuous light - LD light-dark cycle (e.g. LD 16:8 is a cycle of 16 h of light and 8 h of darkness) - TC thermoperiodic cycle (e.g. TC 16:8 (27°: 15°) is a thermoperiod with a 16 h thermophase of 27 °C and an 18 h cryophase of 15°C)     

Regio- and stereo-selective synthesis of vinyl glucose ester catalyzed by an alkaline protease of Bacillus subtilis

The transesterification of -d-glucose with divinylsuccinate, divinyladipate and divinylsebacate in pyridine at 55 °C for 3 days was catalyzed by an alkaline protease from Bacillus subtilis to give corresponding 6-O-vinyl glucose esters at 30%, 53% and 35% yield, respectively. The stereo-selectivity of the alkaline protease toward the -anomer was affected by the acyl donor chain length. 6-O-Vinylsuccinyl-d-glucose was mixture of - and -anomers (/=44/56), the other two products were the pure -d-glucose derivatives.     

Species diversities analyzed by density and cover in an early volcanic succession

To evaluate alpha diversities, various variables such as density, cover, volume, and weight have been used. However, density is often a distinct variable from the remaining three. To clarify differences in diversity measured by those two kinds of variables, the data collected in fourteen 2×5 m permanently-marked plots on Mount Usu, Japan, which erupted during 1977 and 1978 in growing seasons from 1983 to 1989 was analyzed, using Shannon's species diversity (H) that is represented as a result of combination of species richness and evenness (J). H and J were evaluated by density (density H and J) and cover (cover H and J). Cover H and J were significantly lower than density H and J, indicating that cover H has different characteristics from density H. Those differences are due to differences in evenness, because species richness is the same. The rank orders of species density are different from those of cover. The predominance of a few perennial herbs greatly decreases cover evenness, while seedling establishment success influences density evenness. Therefore, I propose that, during the early stages of succession on harsh environments such as volcanoes, density diversity represents seedling establishment success rate while cover diversity expresses vegetative reproduction success rate.     

Endogenous abscisic acid and 2-trans-abscisic acid in alternate bearing ‘Wilking’ mandarin trees

The relationship of abscisic acid (ABA) and 2-trans-abscisic acid (t-ABA) to alternate bearing has been examined in Wilking mandarin (Citrus reticulata Blanco) trees. Leaves, stems and buds of trees loaded with fruit (on trees) had 4.3, 6.0 and 2.2 fold higher ABA levels than the corresponding organs from off trees. Leaves had higher ABA levels than stems and buds in both on and off trees. t-ABA was non-detectable in Wilking leaf, stem and bud tissue. Amounts of t-ABA not exceeding 40% of the ABA content, were found in Shamouti and Valencia orange buds and in Wilking fruit peel.The elevated levels of ABA in on tree organs may reflect a stress imposed by the fruit overload.     

Occurrence of pppApp-synthesizing activity in actinomycetes and isolation of purine nucleotide pyrophosphotransferase

The occurrence of adenosine 5-triphosphate-3-diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, Actinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and imperfecti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeniety from the culture filtrate. The enzymes are a monomeric protein with a molecular weight of 18000–26000 and synthesize adenosine, guanosine and inosine 5-phosphate (mono, di or tri)-3-diphosphate such as pApp, ppApp, pppApp, pGpp, ppGpp, pppGpp and pppIpp by transferring a pyrophosphoryl group from the 5-position of ATP, dATP and pppApp to the 3-position of purine nucleotides in the presence of a divalent cation and in alkaline state.Abbreviations pppApp adenosine 5-triphosphate 3-diphosphate - ppApp adenosine 5-diphosphate 3-diphosphate - pApp adenosine 5-monophosphate 3-diphosphate - pppGpp guanosine 5-triphosphate 3-diphosphate     

Phylogenetic Relationships of the Seven Coat Protein Subunits of the Coatomer Complex, and Comparative Sequence Analysis of Murine Xenin and Proxenin

The coatomer complex is involved in intracellular protein transport and comprises an assembly of seven polypeptide subunits designated , , , , , , and COP. Rooted phylogenetic trees constructed from the full-length cDNA and amino acid sequences of 49 COP entities in different eukaryotes from yeast to man generally revealed striking conservation of each subunit through evolution. Both nucleotide and protein trees displayed close relationships between and subunits, between and subunits, and between and subunits, implying evolution from common ancestors as well as functional similarity. Interestingly, although 6 out of 7 -COP genes appeared to be grouped and related to the -COP genes, 4 out of 7 -COP gene products clustered with other groups of other COP subunit proteins. A 5 coding segment of the murine -COP gene was amplified by RT-PCR and cycle-sequenced. The partial predicted amino acid sequence of this murine homolog was exactly identical to the human and bovine counterparts. Of particular significance was the complete identity of the first 25 and 35 N-terminal residues which constitute the gastrointestinal hormone xenin and its precursor proxenin, thus emphasizing their strict evolutionary conservation and alluding to their physiological importance.     

Specialized and generalized dispersal systems: where does ‘the paradigm’ stand?

I explore the specialization versus generalization paradigm in frugivory and seed dispersal. This view predicts that some tropical trees produce nutritious fruits adapted for use by a small coterie of specialized frugivores that provide reliable seed dissemination. Other tree species are expected to offer superabundant fruits of lower nutritional reward, relying instead on common opportunistic frugivores that are individually less reliable, but collectively disperse seeds effectively. Though widely referenced, many aspects of the paradigm are untested with tropical trees and avian frugivores, primarily because plant ecologists rarely determine whether specialist or generalist foragers are responsible for different patterns of seed distribution, while students of foraging behavior rarely determine the effects seed dispersal by different animals for survival of seeds or seedlings of specialist or generalist trees.Ecological paradigms provide alternative hypotheses, without evolutionary arguments. Keystone species have ecological effects disproportionate to their abundance; it is important for management considerations to know whether fruiting trees or frugivores serve as keystone mutualists in tropical forests. Alternatively, the extent to which vertebrate seed dispersers influence density-dependent seed, seedling, sapling, or adult mortality may have important consequences for spatial dispersion and population dynamics of tree species in tropical forests.     

Protonmotive force in Brevibacterium flavum: the lack of intracellular pH homeostasis

Brevibacterium flavum 22LD-P cells were shown to maintain a transmembrane pH gradient (pH) from 0.6 to 1.8–2 units and a transmembrane electric potential difference () from 0 to 200 mV depending on the pH and ionic composition of the incubation medium, grwoth substrate and concentration of cells. decreased from 120–140 mV to 0 when medium pH was lowered from neutral to 5.0–5.5 and increased to 180–200 mV when medium pH was raised to 8–9 in cells utilizing acetate or endogenous substrate. Cells growing on sucrose, kept around 100–120 mV at neutral as well as acidic medium pH. Intracellular pH in the acetate utilizing or endogenously respiring cells was maintained with the range of 8.9 to 5.5 at medium pH ranging from 9.1 to 4.0, respectively. Sucrose grown cells were able to maintain a more stable intracellular pH. Endogenously respiring cells in potassium phosphate buffer at high biomass concentrations maintained larger pH and relatively smaller , than the same cells in diluted suspensions. Cells in sodium phosphate buffer possessed larger and almost no pH, but was still dependent on biomass concentration.The lack of intracellular pH homeostasis and the collapse of at acid medium pH are discussed in the context of cell membrane proton permeability.     

The inheritance of host plant resistance and its effect on the relative infection efficiency of Magnaporthe grisea in rice cultivars

The inheritance of host plant resistance and its effect on the relative infection efficiency for leaf blast was studied in the crosses IR36/CO39 (partially resistant × highly susceptible) and IR36/IR64 (both partially resistant). On the natural scale, gene action appeared multiplicative. After log transformation, additive effects described most of the genetic variation in the cross IR36/CO39, while additive and dominance effects were about equal in magnitude in the cross IR36/IR64. Dominance was towards increased resistance. No transgressive segregation occurred in the cross IR36/CO39. The number of genes that reduce lesion number was estimated to be zero in CO39 and five or more in IR36. The cross IR36/IR64 showed transgressive segregation in both directions, and IR36 and IR64 each contain at least one gene that is not present in the other cultivar. The heritabilities (narrow sense) in the F₂ were low (range 0.06–0.16), while narrow sense heritabilities based on F₃ lines were much higher (range 0.41–0.68). Lesion numbers in F₃ lines were reasonably correlated with those in F₅ progenies derived from the same F₂ plant (r was±0.6 in both crosses). Partial resistance can be effectively improved by selecting the most resistant plants from the most resistant F₃ lines.     

Spectral position control of dye absorption band maximum in an orienting matrix

The continuous control of the maximum position of the dye absorption band (the zero of the derivative dD ()/d of the cell's optical density D ()) in a nematic matrix is demonstrated experimentally, as a result of changing the angle between the optical axis of a planar-oriented sample and the plane of polarization of absorbed light incident normal to the optical axis. The theory proposed describes quantitatively the experimental dependence (). The rotation of the polarizer with given frequency results in the spectral position modulation of the solute band maximum () within (=0°)–(90°)=700 cm^–1.     

High D-glucose does not affect binding of α-tocopherol to human erythrocytes

The role of -tocopherol uptake system in human erythrocyte in the uptake of plasma -tocopherol has been suggested. However no information is available on -tocopherol uptake activity of human erythrocytes in the presence of high levels of D-glucose which is known to lead to pathological alterations in different cells including human erythrocytes. Therefore, in order to examine the effect of D-glucose on the binding of -tocopherol to human erythrocytes, the binding characteristics of -tocopherol to these cells were established first. Binding of [3H]-tocopherol to human erythrocytes was both saturable and specific. Scatchard analysis of -tocopherol binding to these cells showed the presence of two independent classes of binding sites with widely different affinities. The high affinity binding sites had a dissociation constant (Kd1) of 90 nM with a binding capacity (n1) of 900 sites per cell, whereas the low affinity binding sites had a dissociation constant (Kd2) of 5.2 M and a binding capacity (n2) of 105,400 sites per cell. Trypsin treatment abolished all the -tocopherol binding activity. Competition for the binding of -tocopherol to human erythrocytes was effective with other homologues of -tocopherol (-tocopherol, -tocopherol and -tocopherol) and their potency was almost equal to -tocopherol itself. The order of preference was -tocopherol > -tocopherol -tocopherol -tocopherol. Incubation of human erythrocytes with various concentrations of D-glucose did not affect -tocopherol uptake activity. Our data demonstrate the presence of an -tocopherol uptake system in human erythrocytes and that the -tocopherol uptake activity is not modulated by the presence of D-glucose.     

Genetic analysis of two wheat cultivars, ‘Sonalika’ and ‘WL 711’ for reaction to leaf rust (Puccinia recondita)

Summary Genetic analysis for leaf rust reaction of two widely adapted cultivars, Sonalika and WL 711, has been done using 21 near isogenic Lr lines and rust culture IL004 — avirulent on the two cultivars and all the Lr lines used. The segregation pattern in the F₂ generation indicated the presence of a recessive gene in Sonalika and of a dominant gene in WL 711. These genes in cultivars Sonalika and WL 711 have been identified as Lr 11 and Lr 13, respectively. Gene Lr 13 is no longer effective in WL 711 but it continues to give field resistance in the backgrounds of Chris, Prelude and Thatcher. There has been no significant change in the virulence spectrum of the leaf rust pathogen in India with the release of WL 711. High susceptibility of WL 711 seems to be due to the evolution of more aggressive forms of the pathogen to this cultivar. The gene Lr 11, which behaves as a recessive in Sonalika, was effective against leaf rust when this cultivar was released. The high susceptibility of Sonalika is probably due to an increase in the frequency of race 77 virulent on Lr 11. Lr 11 has shown a dominance reversal in the background of Sonalika. Present results suggest that interaction of resistance genes with the background genotype must be studied for their effective use in breeding programme.     

Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

Transformation of Atriplex gmelini plants from callus lines using Agrobacterium tumefaciens

Atriplex gmelini plants were regenerated via organogensis from hypocotyl explants. Callus lines were induced from the hypocotyl explants on Linsmaier and Skoog (LS) medium supplemented with 1 M benzyladenine and 5 M -naphthaleneacetic acid in the dark. Shoots were regenerated from the callus lines on LS medium supplemented with 20 M thidiazuron and 0.1 M -naphthaleneacetic acid under a high-intensity light condition (450 mol m^–2 s^–1). The regenerated shoots were rooted on LS medium without growth regulators to obtain fully developed plants. We succeeded in transforming Atriplex gmelini from callus lines using Agrobacterium tumefaciens.     

Genotype effects on plant regeneration in callus and suspension cultures of Avena

Regenerative potential of the calli of nineteen genotypes of Avena sativa, Avena nuda, Avena byzantina and one interspecific hybrid were compared over three successive cultures. Highly significant genotype and genotype × subculture interactions were observed. Among the highest plant regenerable genotypes were Corbit (first subculture); GAF/Park and 88Ab3073 (second subculture); and GAF/Park and 87Ab5932 (third subculture). These genotypes regenerated on an average 10 to 17 plants each from a 200 mg callus mass after a 30 to 45 proliferation period. GAF/Park, a progeny of an interspecific cross, regenerated plants at a significantly higher level (11.85 plants/rep), followed by the similarly performing A. sativa (6.23 plants) and A. nuda (5.06 plants) genotypes, which were significantly higher than the A. byzantina genotypes (2.07 plants). Four genotypes were tested for their adaptability to suspension culture and plant regeneration potential by separating their cells and cell clusters into two sizes: larger and smaller than 3 mm. Larger clusters yielded plants for three genotypes GAF/Park, 88Ab3073, and Tibor. The smaller clusters only regenerated plants for GAF/Park and 88Ab3073. From one gram of callus used to initiate suspensions of GAF/Park and 88Ab3073, 119.9 and 18.8 plants, respectively, were regenerated. The plants regenerated for various genotypes from agar-solidified or suspension culture experiments had normal growth and seed set. This study confirms high and sustained regenerative capabilities of GAF/Park, a restricted genotype due to the weedy Avena fatua genetic background and identifies alternative genotypes, especially 88Ab3073 for future tissue culture and transformation studies.     

Bi-antennary oligo-(N-acetyllactosamino)glycans of I-type are galactosylated preferentially at the GlcNAcβ1-6Gal linked arms by α1,3-galactosyltransferase of bovine thymus

1,3-Galactosylation of radiolabelled bi-antennary acceptors Gal1-4GlcNAc1-3(Gal1-4GlcNAc1-6)Gal-R (R=1-OH, 1-4GlcNAc or 1-4Glc) with bovine thymus 1,3-galactosyltransferase was studied. At all stages of the reactions the three acceptors reacted faster at the 1 6 linked arm than at the 1 3 linked branch. Hence, in addition to the doubly 1,3-galactosylated products, practically pure Gal1-4GlcNAc1-3(Gal1-3Gal1-4GlcNAc1-6)Gal-R could be obtained from the three acceptors in reactions that had proceeded to near completion. The isomeric mono-1,3-galactosylated products were identified by using exoglycosidases to remove the branches unprotected by 1,3-galactoses and by subsequently identifying the resulting linear glycans chromatographically.Abbreviations Gal d-galactose - GlcNAc N-acetyl-d-glucosamine - Lac lactose - LacNAc Gal1-4GlcNAc - MH maltoheptaose - MP maltopentaose - MT maltotriose - MTet maltotetraose - WGA wheat germ agglutinin - 3 position 3 of the galactose unit of LacNAc or Lac - 6 position 6 of the galactose unit of LacNAc or Lac