Ganglioside-cholera toxin interactions: a binding and lipid monolayer study

Summary On t.l.c. plates ¹²⁵I-cholera toxin binds to a disialoganglioside tentatively identified as GD_lb with about 10 times less capacity than to ganglioside GM₁. Binding of labeled toxin to both gangliosides was abolished in presence of excess amounts of unlabeled B subunit. Ganglioside extracts from human or pig intestinal mucosa showed toxin binding to gangliosides GM₁ and GD_1b. In ganglioside-containing lipid monolayers the penetration of the toxin was independent of the ganglioside binding capacity.Abbreviations GM₂ Gal-NAc14Gal(3-2NeuAc)14G1c1Cer - GM₁ Gal3Ga1-NAc14Gal(32NeuAc)14G1c11Cer - GD_1a NeuAc23Ga113Gal-NAc14Gal(32NeuAc)14G1c11Cer - GD1b Gall3Gal-NAcl4Gal(32NeuAc82NeuAc)14Glc11Cer - GT_1b NeuAc23Ga113Ga1-NAcal4Gal(3-2NeuAc82NeuAc)14G1c11Cer - dpPC 1,2-hexadecanoyl-sn-glycero-3-phosphocholine - dpPE 1,2-hexadecanoyl-sn-glycero-3-phosphoethanolamine     

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.     

Metabolite detection in Rhodococcus benzothiophene desulfurization using reversed-phase solid-phase extraction and a derivatization technique

Hydrophilic benzo[b]thiophene metabolites produced by Rhodococcus sp. strain T09 were isolated by a solid-phase extraction and a derivatization method, which prevented the dehydration that often occurs during liquid-liquid extraction (LLE), and were identified by GC with atomic emission detection and GC-MS. As a result, cis- or trans-2-(2-hydroxyphenyl) ethen-1-ol, previously reported as the tautomer 2-(2-hydroxyphenyl) ethan-1-al, and 2-(2-hydroxyphenyl) ethen-1-sulfenic acid and its isomer, 1-(1-hydroxyethenyl) benzene-2-sulfenic acid, were identified. Benzothiophene desulfurization in culture broth at neutral pH by the strain T09 was modified as a branched metabolism from benzothiophene S-oxide based on the above compounds.     

The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

The impact of domestication on the genetic variability in the orange carrot,cultivated Daucus carota ssp. sativus and the genetic homogeneity of various cultivars

Summary Isozyme analysis of wild and domesticated accessions indicated that domestication of the cultivated carrot Daucus carota ssp. sativus resulted in an insignificant reduction of all genetic variability and genetic distance estimates. Although they are less variable genetically, cultivated forms maintain a high proportion of observed heterozygosity. Relative to the overall genetic variability of the species, samples from four common cultivars Red Cored Chantenay, Scarlet Nantes, Danvers Half Long and A Plus demonstrated a high degree of genetic similarity. This is attributed to the recent development of orange cultivars and the limited gene pool utilized in their development.     

Use of15N/14N rations to evaluate the food source of the mysid,Neomysis intermedia Czerniawsky,in a eutrophic lake in Japan

The stable isotope ratios of nitrogen were measured in the mysid,Neomysis intermedia, together with various biogenic materials in a eutrophic lake, Lake Kasumigaura, in Japan throughout a year of 1984/85. The mysid, particulate organic matter (POM, mostly phytoplankton), and zooplankton showed a clear seasonal change in ¹⁵N with high values in spring and fall, but the surface bottom mud did not. A year to year variation as well as seasonal change in ¹⁵N was found in the mysid. The annual averages of ¹⁵N of each material collected in 1984/85 are as follows: surface bottom mud, 6.3 (range: 5.7–6.9); POM, 7.9 (5.8–11.8); large sized mysid, 11.6 (7.7–14.3); zooplankton, 12.5 (10.0–16.4); prawn, 13.2 (9.9–15.4); goby, 15.1 (13.8–16.7). The degree of¹⁵N enrichment by the mysid was determined as 3.2 by the laboratory rearing experiments. The apparent parallel relationship between the POM and the mysid in the temporal patterns of ¹⁵N with about 3 difference suggests the POM (mostly phytoplankton) as a possible food source ofN. intermedia in this lake through the year.     

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     

Physiological relationship between the temperate phages lambda and phi80

Summary This work deals with the ability of phage 80 to provide defective mutants of with their missing functions. Functions Involved in Recombination. As shown by others, the Int mechanism of 80 cannot excise prophage . However, 80 efficiently excises recombinants from tandem dilysogens, using its Ter mechanism. Likewise, the nonspecific mechanism Red is interchangeable between 80 and . Maturation of DNA by 80. The Ter recombinants excised by 80 from tandem dilysogens are packaged into a 80 protein coat. This contrasts with the fact, already mentionned by Dove, that 80 is extremely inefficient for packaging phage superinfecting a -lysogen. The latter result is also found when the helper phage is a hybrid with the left arm of (80hy4 or 80hy41 — see Fig. 1). However, the maturation of the superinfecting is much more efficient if the 80hy used as a helper has the att-N region of (like 80hy1). Conversely a with the att-N region of 80 (hy6 — see Fig. 1) is packaged more efficiently by 80 or 80hy4 than by 80hy1. It is suggested that the maturation of chromosome superinfecting an immune cell requires a recombination with the helper phage. Vegetative Functions. Among the replicative functoons O and P, the latter only can be supplied by 80. That N mutants are efficiently helped by 80 does not tell that 80 provides the defective with an active N product; the chromosomes are simply packaged into a 80 coat. This shows that 80 is unable to switch on the late genes of . That neither 80 nor any of the 80hy tested can provide an active N product is shown in a more direct way by their complete failure to help N ^-r₁₄; this phage carries a polar mutation which makes the expression of genes O and P entirely N-dependant. The maturation of a N ^- by 80 contrasts with the fact that mutants affected in late genes (A, F or H) are not efficiently helped by 80. This suggests that the products coded by these genes are not interchangeable between 80 and , and that packaging of DNA into 80 coats is possible but inhibited when late proteins are present in the cell. Activation of the Late Genes. Among the im ₈₀ h ⁺ hybrids tested, only 80hy41 is able to switch on the late genes of a N defective mutant. This hybrid differs from the other hybrids studied here, by the fact that it has the Q-S-R region of (see Fig. 1). The results are consistant with the view that the product of Q gene is sufficient for activating the late genes of a DNA. N would thus control the expression of late genes only indirectly by controlling the expression of gene Q (Couturier & Dambly have independantly reached the same conclusion, 1970). Furthermore the failure of 80 and of the 80hy1 and 80hy4 to activate the late genes of would imply that these phages are unable to provide an Q product active on the chromosome Reciprocally, switches on the late genes of prophage 80hy41, but not of prophages 80hy1 and 80hy4. This suggests that the initiation of late genes expression takes place at a main specific site located in the Q-S-R region of the chromosome. The expression of the late genes would thus be sequential, and proceed through the left arm only when steaky ends cohere. Similar conclusions were reached independantly by Toussaint (1969) and by Herskowitz and Signer (1970).

---

---

Ce travail a été réalisé dans le cadre du contrat d'association Euratom-U. L. B. 007-61-10 ABIB et avec l'aide du Fonds de la Recherche Fondamentale Collective.     

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.     

Sublittoral macrozoobenthic assemblages in the enclosed sediment-polluted Rhine-Meuse Delta; their relationship to environmental conditions

Composition, densities and biomass of sublittoral macrozoobenthos were investigated at 14 sites in the enclosed Rhine-Meuse Delta. The aim was to identify the main macrozoobenthic assemblages and to establish their relationship with environmental conditions, including sediment pollution. Most sites were dominated by the tubificidsLimnodrilus hoffmeisteri andL. claparedeanus. Four zoobenthic assemblages could be identified. They are related to different geomorphological phases of a basin filling up with fluvial sediment causing a longitudinal sediment gradient. The Rhine river assemblage was found in the Nieuwe Merwede, filled up in the 1970's, the soft mud assemblage in the Hollands Diep at sites with high sedimentation rates; the basin silt assemblage in the Amer, Hollands Diep and Haringvliet, at sites with lower sedimentation rates, and the basin shoal assemblage at former flats with low sedimentation rates. CANOCO was used to relate the TWINSPAN indicator species to a selection of environmental parameters. Sediment pH, water content, sand fraction, total polycyclic aromatic hydrocarbons (PAH) and current velocity explained 44% of the variance of the average abundance of the indicator taxa per site. Sediment firmness, indicated by sediment water content, and high ammonium concentrations probably were together responsible for the very low densities in the soft mud assemblage. Densities and biomasses in the other assemblages were low as well, except for theDreissena polymorpha habitat, where very high total zoobenthic biomass values (max. 55.8 g m^–2) were observed. It is argued that sediment contamination has a considerable impact on macrozoobenthic densities and species composition in all assemblages, the basin shoal assemblage excepted.     

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)     

Partial mispairing and crossing-over between β0 and δ genes as the origin of the δ β0 thalassemia gene

Summary Two double heterozygous ⁰/⁰ thalassemic sibs of Mexican descent were studied. The father had a ⁰/⁰ genotype, while the mother, one sib and several maternal relatives were ⁰/⁰ heterozygotes. Parental consanguinity and an apparently low frequency of thalassemia among Mexicans suggested a possible common origin of both ⁰ and ⁰ genes. A hypothesis to explain such a possibility is proposed on the basis of a partial mispairing between ⁰ and genes followed by a crossing-over which would results in a ⁰ recombinant gene. This hypothesis could also be extended to explain the 22 gluala, 22 alaglu and 116 arghis Hb variants as recombinants from double crossing-over between and mispaired genes for which the name interstitial-Lepore is proposed.     

Immature embryo rescue,culture and seedling development of acid citrus fruit derived from interploid hybridization

Interploid sexual hybridizations were completed in 2001 and 2002 between seven lemon (Citrus limon(L.) Burm. f.) varieties, Key lime (C. aurantifolia (Cristm.) Swing), Palestine sweet lime (C. imettioides Tan.), Lakeland limequat (C. aurantifolia x Fortunella japonica (Thumb.) Swing.), and Etrog citron (C. medica L.) as diploid progenitors and four allotetraploid somatic hybrids (Key lime + Valencia orange, Hamlin orange + Femminello lemon, Valencia orange + Rough lemon, and Valencia orange+ Femminello lemon) in efforts to generate improved seedless triploid acid fruit hybrids. Efficient recovery of triploid progeny from such crosses requires embryo rescue to avoid embryo abortion due to endosperm failure. Germination of rescued genetically diverse immature embryos was induced on two culture media (EME and Gamborgs B5), with two sucrose concentrations (50 or 70 g l^–1). All media contained 0.5 g l^–1 malt extract and 4.50 M GA₃. Germination of globular, heart and torpedo shaped embryos (defined as small embryos) was significantly (p < 0.05) affected by medium and genotype. Gamborgs medium induced 82.89% germination. Of germinated embryos, 11–65% developed into normal plants with differences among crosses. Cotyledonary embryos (defined as immature embryos with fully developed cotyledons) germinated and developed into normal plants at higher rates than less-developed embryos. In efforts to improve the efficiency of plant recovery, small embryos from Todo el año × HF and Lisbon × HF crosses conducted during 2002 were rescued and cultured on three media (MS, Gamborgs, and RMA) for comparison. Media did not significantly affect the proportion of normal plant recovery.     

Observation of a distinct transition in the mode of interconversion of ring pucker conformers in non-crystalline d-ribose-2'-d from 2H NMR spin-alignment

Internal motions of d-ribose selectively ²H-labeled at the 2 position were measured using solid state ²H NMR experiments. A sample of d-ribose-2 -d was prepared in a hydrated, non-crystalline state to eliminate effects of crystal-packing. Between temperatures of –74 and –60°C the C2–H2 bond was observed to undergo two kinds of motions which were similar to those of C2–H2/H2 found previously in crystalline deoxythymidine (Hiyama et al. (1989) J. Am. Chem. Soc., 111, 8609–8613): (1) Nanosecond motion of small angular displacement with an apparent activation energy of 3.6 ± 0.7 kcal mol^–1, and (2) millisecond to microsecond motion of large amplitude with an apparent activation energy 4 kcal mol^–1. At –74°C, the slow, large-amplitude motion was best characterized as a two-site jump with a correlation time on the millisecond time scale, whereas at –60°C it was diffusive on the microsecond time scale. The slow, large-amplitude motions of the C2–H2 bond are most likely from interconversions between C2-endo and C3-endo by way of the O4-endo conformation, whereas the fast, small-amplitude motions are probably librations of the C2–H2 bond within the C2-endo and C3-endo potential energy minima.     

Formation ofα,ω-dodecanedioic acid andα,ω-tridecanedioic acid from different substrates by immobilized cells of a mutant ofCandida tropicalis

Summary The metabolic formation of either,-dodecanedioic acid or,-tridecanedioic acid from the individual n-alkane, n-alcohol, n-monoacid and,-diol with corresponding carbon chain length using K-carrageenan entrapped mutants S76 ofCandida tropicalis was studied. The immobilized cells of S76 could also directly produce-hydroxy acid and,-dioic acid from,-diol. With n-alcohol and n-monoacid as substrate, the amount of-hydroxy acid and,-dioic acid produced was also a function of the incubation time.The results demonstrated that in the immobilized cells of S76 the formation of,-dioic acid from n-alcohol can also run both via n-monoacid and via,-diol as well as in the normal cells of S76.     

Genetic heterogeneity of propionic acidemia: Analysis of 15 Japanese patients

Summary Propionic acidemia is an autosomal recessive metabolic disease resulting from a deficiency of propionyl CoA carboxylase (PCC) activity. We have analyzed the molecular heterogeneity of Japanese propionic acidemia patients using anti-human PCC antiserum and cDNA clones coding for the two protein subunits ( and ) of the enzyme. The steady state levels of both and subunits of PCC from 15 Japanese patients were determined by Western blot. Three patients had neither nor subunits, and the amounts of both and subunits were low in 3 other patients. According to our previous data, we classified these 6 patients as having subunit deficiency. In the remaining 8 patients, subunits were normal, but the subunits were aberrant. Two patients had low levels of normal-sized subunits and 6 had subunits smaller than normal in size and greatly reduced in quantity. These 8 patients were assigned to the subunit deficiency category. One patient had apparently normal and subunits. We could not determine this patient's primary defect. These data reveal the genetic heterogeneity of molecular defects causing propionic acidemia in the Japanese. Southern blot analysis did not reveal any gross alteration in gene structure when DNA was digested withHindIII,EcoRI andTaqI. However, DNA from 3 -subunit-deficient patients, when digested withMspI and probed with PCC cDNA, revealed a unique 2.7-kb band not observed in blots of DNA from any other patient or 15 normal controls. We conclude that this alteredMspI restriction map is the result of a mutation in the subunit gene of these patients.     

Epithelial action potentials inOikopleura (Tunicata: Larvacea)

Summary The passive electrical properties and initiation of action potentials have been examined in the external epithelium of oikopleurid larvacean tunicates. The epithelial cells are electrically coupled, and are polygons up to 200 m across and up to 1.4–2.8 m thick. Membrane constants determined by a 2-electrode study were forO. dioica:: 922 m; R_m: 4.3 kcm₂; R_i: 82.7 cm. Corresponding values for the largerO. longicauda were: 3350 m; 35.6 kcm²; and 104.5 cm. Mean resting potentials in both species were around 80 mV. Mechanical stimulation evokes over-shooting action potentials propagated (at 18 °C) at some 40 cm/s. These are rapid events, repolarisation being almost complete in 5 ms. There is no undershoot.When the recording electrode penetrates the epithelial cell from its inner surface distant mechanical stimulation may evoke similar action potentials arising from the stimulus site, but more often evokes graded small depolarisations which give rise to action potentials with increasing strength of mechanical stimulation. Reasons are given for considering these to be generator potentials resulting from deformation of the outer epithelial cell membrane by the tip of the recording electrode. The effects of epithelial action potentials upon the potentials recorded from the caudal muscle cells are briefly described.     

Solution conformations of proline rings in proteins studied by NMR spectroscopy

Summary Three different conformations of proline rings in a protein in solution, Up, Down and Twist, have been distinguished, and stereospecific assignments of the pyrrolidine -, - and -hydrogens have been made on the basis of ¹H-¹H vicinal coupling constant patterns and intraresidue NOEs. For all three conformations, interhydrogen distances in the pairs -³, ³-³, ²-², ²-², and ³-³ (2.3 Å) are shorter than those in the pairs -², ²-³, ³-², ²-³, and ³-² (2.7–3.0 Å), resulting in stronger NOESY cross peaks. For the Up conformation, the ³-² and ²-³ spin-spin coupling constants are small (<3 Hz), and weak cross peaks are obtained in a short-mixing-time (10 ms) TOCSY spectrum; all other vicinal coupling constants are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. For the Down form, the -², ²-³, and ³-² vicinal coupling constants are small, leading to weak TOCSY cross peaks; all other couplings again are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. In the case of a Twist conformation, dynamically averaged coupling constants are anticipated. The procedure has been applied to bovine pancreatic trypsin inhibitor and Cucurbita maxima trypsin inhibitor-V, and ring conformations of all prolines in the two proteins have been determined.     

Meiosis and fertility of F1 hybrids between hexaploid bread wheat and decaploid tall wheatgrass (Thinopyrum ponticum)

As the first step in the transfer of barely yellow dwarf virus resistance and salt tolerance from decaploid tall wheatgrass (Thinopyrum ponticum) into hexaploid bread wheat (Triticum aestivum L.), octoploid intergeneric hybrids (2n = 8x = 56) were synthesized by crossing the tall wheatgrass cultivar Alkar with wheat cvs. Fukuhokomugi (Fuko) and Chinese Spring. (Fuko x Alkar) F₁ hybrids were studied in detail. The F₁ hybrids were perennial and generally resembled the male wheatgrass parent with regard to morphological features and gliadin profile. Most hybrids were euploid with 56 chromosomes and showed high chromosome pairing. On an average, in 6 hybrids 83.6% of the complement showed chiasmatic association, some between wheat and wheatgrass chromosomes. Such a high homoeologous pairing would be obtained if Ph1, the major homoeologous pairing suppressor in wheat, was somehow inactivated. Some of the Fuko x Alkar hybrids had high pollen fertility (18.5–42.0% with a mean of 31.5%) and high seed fertility (3–29 seeds wtih a mean of 12.3 seeds per spike), offering excellent opportunities for their direct backcrossing onto the wheat parent.     

Analogues of NADP+ as inhibitors and coenzymes for NADP+ malic enzyme from maize leaves

Structural analogues of the NADP⁺ were studied as potential coenzymes and inhibitors for NADP⁺ dependent malic enzyme from Zea mays L. leaves. Results showed that 1, N⁶-etheno-nicotinamide adenine dinucleotide phosphate ( NADP⁺), 3-acetylpyridine-adenine dinucleotide phosphate (APADP⁺), nicotinamide-hypoxanthine dinucleotide phosphate (NHDP⁺) and -nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate (23NADPc⁺) act as alternate coenzymes for the enzyme and that there is little variation in the values of the Michaelis constants and only a threefold variation in V_max for the five nucleotides. On the other hand, thionicotinamide-adenine dinucleotide phosphate (SNADP⁺), 3-aminopyridine-adenine dinucleotide phosphate (AADP⁺), adenosine 2-monophosphate (2AMP) and adenosine 2: 3-cyclic monophosphate (23AMPc) were competitive inhibitors with respect to NADP⁺, while -nicotinamide adenine dinucleotide 3-phosphate (3NADP⁺), NAD⁺, adenosine 3-monophosphate (3AMP), adenosine 2: 5-cyclic monophosphate (25AMPc), 5AMP, 5ADP, 5ATP and adenosine act as non-competitive inhibitors. These results, together with results of semiempirical self-consistent field-molecular orbitals calculations, suggest that the 2-phosphate group is crucial for the nucleotide binding to the enzyme, whereas the charge density on the C₄ atom of the pyridine ring is the major factor that governs the coenzyme activity.Abbreviations NADP⁺ 1, N⁶-etheno-nicotinamide adenine dinucleotide phosphate - NHDP⁺ nicotinamide-hypoxanthine dinucleotide phosphate - APADP⁺ 3-acetylpyridine-adenine dinucleotide phosphate - SNADP⁺ thionicotinamide-adenine dinucleotide phosphate - AADP⁺ 3-aminopyridine-adenine dinucleotide phosphate - 23NADPc⁺ -nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate - 3NADP⁺ -nicotinamide adenine dinucleotide 3-phosphate - 2AMP adenosine 2-monophosphate - 3AMP adenosine 3-monophosphate - 23AMPc adenosine 2: 3 monophosphate cyclic - A adenosine - RuBP ribulose 1,5-bisphosphate - SCF-MO Self-Consistent Field-Molecular Orbitals (method)