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     

DNA markers tightly linked to a gall midge resistance gene (Gm2) are potentially useful for marker-aided selection in rice breeding

We have developed a polymerase chain reaction (PCR)-based assay that could effectively reduce the time period required to screen and select for Gall Midgeresistant rice lines under field conditions. The primers for the assay were designed on the basis of sequence information of two phenotype specific random amplified polymorphic DNA fragments which were found to be tightly linked to Gall Midge biotype-1 resistance gene (Gm2). The two RAPD fragments, F8₁₇₀₀ in the susceptible parent ARC6650 and F10₆₀₀ in the resistant parent Phalguna, were identified after screening 5450 loci using 520 random primers on genomic DNAs of ARC6650 and Phalguna. These primers, when used in a multiplexed PCR, amplified specifically a 1.7-kb and 0.6-kb fragment in the susceptible and resistant parents, respectively. When this assay was performed on genomic DNAs of 44 recombinant inbred lines derived from ARC6650 x Phalguna and 5 lines derived from other crosses where one of the parents was Phalguna, ARC6650 or their derivatives, the primers amplified a 1.7-kb fragment in all of the susceptible lines or a 0.6-kb fragment in all of the resistant ones. These markers can be of potential use in the marker-aided selection of Gall Midge biotype-1 resistant phenotypes. As screening for resistance can now be conducted independent of the availability of insects, the breeding of resistant varieties can be hastened.     

Sex determination in Sarotherodon (tilapia)

Summary The simplest possible model of the sex determination process adding autosomal influence to a minimal number of sex chromosomes was developed to explain matings of Tilapia (Sarotherodon) species. Eighteen different genotypes, each having two autosomes (AA, Aa, or aa) and two sex chromosomes (WX, WY, WW, XY, XX or YY) involved in sex determination, are predicted by the theory. Their sex (10 males and 8 females) were determined using a series of directed graphs, showing the relative strength of the chromosome pairs, developed on the basis of Chen's sex ratio results (Chen 1969). This theoretical model predicts eight different sex ratios (01, 13, 35, 11, 97, 53, 31, 10 ); three of them are not predicted by the WXYZ theory. The greatest part of these sex ratios have been obtained experimentally in extensive series of crosses between related species of Tilapia and their hybrids, carried out by several authors. The theory succeeds in explaining all of Chen's results, including those ratios 53 and 01 seen in certain crosses but not predicted by the WXYZ theory. The importance of the autosomes is seen in comparisons of the genotype pairs (AaWY, aaWY), (AaXY, aaXY) and (AAWW, AaWW) in which the first genotype in each case is male while the second is female as proven by the sex ratio results. The members of the pair differ only in the substitution of one autosome for the other. To test the theory, experiments consisting of hormonal sex reversion and a series of crosses are proposed. Finally, theoretical and practical implications of the theory are discussed.     

An elongated segment of DNA observed between two human α globin genes

Summary Detailed restriction enzyme analysis of the DNA from a Chinese female showed that one of her chromosomes had a >17.5 kb deletion of DNA, including the , 2, and 1 globin genes, which is present in many Southeast Asians with an -thalassemia-1 chromosome. Her normal chromosome had the expected cluster of -like globin genes (5----2-1-3), but the segment of DNA between the two globin genes was elongated by some 0.5–0.7 kb. Analyses of various restriction sites suggested that this normal variant of the human globin gene complex is due to a crossover between a normal chromosome with () and a chromosome with an -thalassemia-2 (–^3.7) and an -21-hybrid gene.     

Average phase difference theory and 1∶1 phase entrainment in interlimb coordination

The dynamics of coupled biological oscillators can be modeled by averaging the effects of coupling over each oscillatory cycle so that the coupling depends on the phase difference between the two oscillators and not on their specific states. Average phase difference theory claims that mode locking phenomena can be predicted by the average effects of the coupling influences. As a starting point for both empirical and theoretical investigations, Rand et al. (1988) have proposed d/dt= — K sin ), with phase-locked solutions =arcsin( /K), where is the difference between the uncoupled frequencies and K is the coupling strength. Phase-locking was evaluated in three experiments using an interlimb coordination paradigm in which a person oscillates hand-held pendulums. was controlled through length differences in the left and right pendulums. The coupled frequency _c was varied by a metronome, and scaled to the eigenfrequency _v of the coupled system K was assumed to vary inversely with _c. The results indicate that: (1) and K contribute multiplicatively to (2) =0 or = regardless of K when =0; (3) 0 or regardless of when K is large (relative to ); (4) results (1) to (3) hold identically for both in phase and antiphase coordination. The results also indicate that the relevant frequency is _c/_v rather than _c. Discussion high-lighted the significance of confirming =arcsin(/K) for more general treatments of phase-locking, such as circle map dynamics, and for the 11 phase-entrainment which characterizes biological movement systems.     

Physical and Epitope Analysis of a Recombinant Human T-Cell Receptor Vα/Vβ Construct Support the Similarity to Immunoglobulin

The genetic organization and protein structure of T-cell receptors (TCR) and immunoglobulins (Ig) are remarkably similar. Through recombinant, physical, and peptide-based immunological studies we demonstrated that rabbit antisera generated against a recombinant single-chain TCR (scTCR) react with defined peptide epitopes of their constituent TCR and chains. These antisera cross-react with the light-chain Mcg as well as with peptides duplicating its covalent structure. Conversely, rabbit antisera generated to human light chains cross-reacted with the recombinant scTCR. Rabbit anti- antibodies purified on an scTCR affinity column bound to T-cell lines and to T and B lymphocytes from peripheral blood. Circular dichroism analysis demonstrated plots characteristic of -sheets for both Mcg and recombinant scTCR. Antisera directed against TCR -chain synthetic peptides reacted with scTCR, Mcg light-chain protein, synthetic peptides from regions of sequence homology in -chains, and Mcg. Based upon this homology and the serological cross-reactions which reflect conformational determinants, we suggest that the V/V antigen-binding domain of this particular monoclonal scTCR construct is substantially similar to the conformational structure of light chains.     

Stimulation by hexose esters of lactate production by rat erythrocytes,insensitivity to 3-O-methyl-D-glucose and inhibition by 2-deoxy-D-glucose and its tetraacetic ester

Selected esters of D-glucose were recently proposed as tools to provide the sugar to cells, whilst bypassing the carrier system for hexose transport across the plasma membrane. In the present study, -D-glucose pentaacetate, -D-glucose pentaacetate, -D-mannose pentaacetate and, to a lesser extent, 6-O-acetyl-D-glucose, all tested at a 1.7 mM concentration, were found to increase lactate production above basal value in rat erythrocytes. Over 90 min incubation, the increment in lactate production ranged from about 1.2 (-D-glucose pentaacetate) to 0.6 (6-O-acetyl-D-glucose) mol/l of erythrocytes. Little or no change in lactate production was observed in cells exposed to -L-glucose pentaacetate, -D-glucose pentaethylsuccinate, -D-galactose pentaacetate or -D-galactose pentaacetate. The metabolic response to -D-glucose pentaacetate was resistant to 3-O-methyl-D-glucose (10-80 mM) which suppressed, however, that evoked by D-glucose. D-mannoheptulose (10 mM) virtually failed to affect the response to D-glucose and its pentaacetate ester. On the contrary, 2-deoxy-D-glucose (10.6 mM) inhibited to the same relative extent (55% decrease) lactate production in erythrocytes exposed to either unesterified D-glucose or -D-glucose pentaacetate. The tetraacetic ester of 2-deoxy-D-glucose was more efficient than unesterified 2-deoxy-D-glucose in inhibiting lactate production from -D-glucose pentaacetate. It is proposed that selected esters of saccharides represent useful tools to bypass defects in hexose transport, and to increase their nutritional or therapeutic efficiency.     

Demonstration of ‘cardiac-specific’ myosin heavy chain in masticatory muscles of human and rabbit

Summary Human and rabbit masticatory muscles were analyzed immuno-and enzyme-histochemically using antibodies specific to cardiac , slow and fast myosin heavy chain isoforms. In human masseter, temporalis, and lateral pterygoid muscle cardiac myosin heavy chain is found in fibres that contain either fast, or fast and slow myosin heavy chain. In rabbit masseter, temporalis and digastric muscles, fibres are present that express cardiac myosin heavy chain either exclusively, or concomitantly with slow myosin heavy chain or fast myosin heavy chain. Our results demonstrate a much broader distribution of cardiac myosin heavy chain than hitherto recognized and these might explain in part the specific characteristics of masticatory muscles. The cardiac myosin heavy chain is only found in skeletal muscles originating from the cranial part of the embryo (including the heart muscle) suggesting that its expression might be determined by the developmental history of these muscles.     

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     

Water stress-induced oxidative damage and antioxidant responses in micropropagated banana plantlets

Oxidative injury and antioxidant responses were investigated in two banana genotypes (Musa AAA Berangan and Musa AA Mas) subjected to 40 % PEG-induced water stress. PEG treatment resulted in oxidative injury, as expressed in increased lipid peroxidation and reduced membrane stability index, in both cultivars; however, greater oxidative injury was detected in Mas. Under PEG treatment, catalase activity and glutathione reductase activity were enhanced in both cultivars, but were higher in Mas. Ascorbate peroxidase activity was enhanced in Berangan under water stress, but was unaffected in Mas. Meanwhile, superoxide dismutase activity was inhibited in both cultivars under water stress, but higher activity was detected in Berangan. Higher ascorbate peroxidase and superoxide dismutase activities were associated with greater protection against water stress-induced oxidative injury.     

Inheritance and linkage of isozyme loci in almond

The segregation of seven isozyme marker genes was investigated using eight controlled crosses in almond. The cultivar Nonpareil was the maternal parent in all crosses. Pollination was achieved using eight different cultivars, and a total of 3200 individual kernels were assessed. For each isozyme the goodness-of-fit test was used to test for departure from the expected frequencies assuming Mendelian inheritance. Given a higher than expected number of significant results for individual isozymes, independent segregation between pairs of isozymes was tested using the chi-square statistic on the resulting two-way contingency tables. In all crosses a highly significant association (P value< 0.001) was observed between (1) the AAT- 1 and IDH isozymes loci and (2) the LAP-1 and PGM-2 isozymes loci, which leads to the conclusion that the respective isozyme pairs are linked.In addition, a significant association (P value < 0.001) was observed between LAP-1 and GPI-2 when the pollen sources were Fritz, Mission, or Price, but this could not be tested for the remaining five pollen sources, Carmel, Grant, Keane, Ne plus Ultra, Peerless, because they are homozygous at these loci. If LAP-1 is linked with GPI-2 and PGM-2, it might be expected that we should find evidence of linkage between GPI-2 and PGM-2. The lack of a significant association between these two isozymes suggests that LAP-1 is located centrally on the chromosome. These three pairs of linked loci are the first to be reported in almond.     

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).

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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.     

Cyanamide mediated syntheses under plausible primitive earth conditions

Summary When an aqueous solution (pH 7.0) of deoxythymidine 5-phosphate, 4-amino-5-imidazolecarboxamide and cyanamide was dried and heated for 18 h at 60°C, P¹, P²-dideoxythymidine 5-pyrophosphate (I) was formed in a 58% yield. Oligonucleotides were not detected in the reaction product. Under conditions employed in the above reaction, (I) was shown to be stable. In prebiotic polymerization reactions employing deoxythymidine 5-triphosphate as the polymerizing species, (I) could therefore function as a primer and minimize the formation of cyclic nucleotides.Abbreviations dT deoxythymidine - dTMP deoxythymidine 5-phosphate - dTppT P¹, P²-dideoxythymidine 5-pyrophosphate - dTTP deoxythymidine 5-triphosphate - AICA 4-amino-5-imidazolecarboxamide     

Heterochromatin banding in the genus Paris

The heterochromatin content of new accessions of the genus Paris have been studied using C banding and Q banding techniques. Supernumerary chromosomes in two accessions are shown to differ in their heterochromatin content. The results are related to previous cytogenetic work in the genus Paris.     

Utilization of 5-fluorouracil byMyobacterium avium

Myobacterium avium LM1 was exposed to concentrations of 5-fluorouracil (5FU) that ranged from 0 to 100 g/ml. Growth inhibition was inversely proportional to the concentration of the drug. DNA was extracted from cells grown in medium that contained [¹⁴C]5FU, but no carrier. The [¹⁴C]DNA was enzymatically hydrolyzed to deoxyribonucleotides, which were separated and fractionated by high-performance liquid chromatography (HPLC). The isotope was located in 2-deoxycytidine 5-monophosphate (dCMP) and 2-deoxythymidine 5-monophosphate (dTMP), with dCMP containing the majority. There was no radioactivity at the elution times for 5-fluoro-2-deoxyuridine 5-monophosphate or 2-deoxyuridine 5-monophosphate. These results suggested that 5FU was dehalogenated and the uracil moiety ultimately converted into cytosine and thymine deoxyribonucleotides. Cells were grown in [³H]uracil, and [³H]DNA was extracted and analyzed by HPLC. The isotope was found only in the pyrimidine deoxyribonucleotides, with dCMP containing 4.1 times that in dTMP. Thus, it was demonstrated that uracil and dehalogenated 5FU were not directly incorporated into DNA, but rather converted to cytosine and thymine and then incorporated into DNA by a salvage pathway.     

Carotenoid pigments of Stigmatella aurantiaca (Myxobacterales)

Summary In this first article on the carotenoids of Myxobacterales we report on the minor carotenoids of Stigmatella aurantiaca: phytoene, phytofluene, lycopene, -carotene, 4-keto--carotene, 1,2-dihydro-1-hydroxy--carotene, 4-keto-1,2-dihydro-1-hydroxy--carotene, 4-keto-1,2-dihydro-1-hydroxy-torulene, and 1,2,1,2-tetrahydro-1,1-dihydroxy-lycopene. These pigments account for about 10% of total carotenoids.     

Studies on the E. coli groNB (nusB) gene which affects bacteriophage lambda N gene function

Summary Escherichia coli mutants, called groNB, which block the growth of bacteriophage at the level of action of the gene N product, have been isolated as survivors at 42°C of bacteria carrying a) the defective prophage bio1 1 i cI857 H1 or b) the pcR1 plasmid containing the EcoRI immunity fragment of phage cI857. In addition, groNB bacterial mutants have been isolated at 37° C, as large colony formers in the presence of i cI h ⁴³⁴, i cI h , and i cI h ⁸⁰ phage. The groNB locus is located at 9 minute of the E. coli genetic map with the order of the neighboring loci being proC tsx groNB purE. Most groNB mutations isolated at 42° C were found to interfere in addition with bacterial growth at low temperatures, since (a) the GroNB phenotypes of growth inhibition and bacterial cold sensitivity cannot be separated by P1 transduction, and (b) some cold resistant revertants simultaneously become Gro⁺ for growth. Lambda transducing phages carrying the groNB ⁺ bacterial gene have been isolated. GroNB mutant bacterial lysogenized by the transducing phage acquire the Gro⁺ phenotype and simultaneously the cold resistant phenotype, suggesting that the groNB mutations are recessive to the wild-type gene.     

Organization of α-chain genes among Hb G-Philadelphia heterozygotes in association with Hb S, β-thalassemia,and α-thalassemia-2

The percentages of the -chain variant Hb G-Philadelphia (Hb G) or ₂ 68 AsnLys₂ were evaluated in 84 adult and 18 newborn heterozygotes. These included members of three families who were studied in more detail by nucleic acid hybridization techniques. The adult heterozygotes fell in two categories, one with a higher proportion of Hb G [46.5±1.0% (SD), N=21] and another with lower values (33.9±3.4%, N=63). Among the newborn heterozygotes, two babies fell in the category with the higher proportion of Hb G while 16 babies gave values between 25 and 34%. Studies of -chain gene organization on the parents of one neonate with a Hb G level of 27% at birth and 37% at 8 months excluded the presence of chromosomes with triplicated -chain genes which could lead to the ^0G/ genotype. Rather, these studies on five Hb G heterozygotes from three families confirmed the linkage between Hb G and a specific type of -thalassemia-2 associated with the presence of a 16-kbp Bgl II fragment which most probably carries the ^G locus since it has been found in 19 Hb G heterozygotes studied to date. The presence of an -thal-2 heterozygosity and three -chain genes (^0G/) was confirmed among Hb G heterozygotes with lower proportions of this variant. It is likely that the even lower values found in some newborn could arise through defective assembly of ^G- dimers. The presence of an -thal-2 homozygosity and two active -chain genes, one on each chromosome (^0G/⁰), was confirmed among heterozygotes with the higher proportion of Hb G. One of each of these categories was present in each of the three families investigated. This type of variability in the number of active -chain genes due to a heterozygosity or a homozygosity for -thalassemia-2 explains the trimodality of Hb S percentages among heterozygotes and the atypical hematological or biosynthetic features among patients with -thalassemia and sickle-cell syndromes.This research was supported by USPHS Research Grants HLB-05168 and HLB-15158 and by designated research funds of the Veterans Administration. This is Contribution No. 0693 of the Department of Cell and Molecular Biology, Medical College of Georgia, Augusta.     

Adoptions expérimentales de larves entre des fourmis de genres différents (II):Myrmica laevinodis Nylander etAnergates atratulus Schenck

Résumé Nous avons fait élever des larves d'Anergates atratulus par des ouvrières deMyrmica laevinodis à 22°C. Pour y parvenir, il n'est pas utile de faire hivernerensemble les larves d'Anergates et les ouvrières deMyrmica. La présence de larves autochtones n'empêche pas lesMyrmica d'élever des larves d'Anergates. Dans toutes les expériences lesMyrmica ont été soumises au fridavant de recevoir des larves d'Anergates. Aucune reine deMyrmica n'a été utilisée dans ces expériences.Sur les 64 larves d'Anergates que nous avons utilisées, 38 se sont transformées en imagos. C'est au début de l'adoption et au moment des métamorphoses que périrent la plupart des 26Anergates perdus. Les femelles vécurent en général 2 ou 3 jours et cherchèrent très tôt à quitter le nid natal. Les mâles vécurent 2 à 3 semaines.

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Summary Larvae ofAnergates atratulus were experimentally reared by workers ofMyrmica laevinodis, at 22°C. An overwintering of both larvae ofAnergates and workers ofMyrmica is not necessary for the success of that experiment. The presence of larvae ofMyrmica does not keep theMyrmica from rearing larvae ofAnergates. The workers ofMyrmica have been cooled, in all the experiments, before receiving larvae ofAnergates. No queen ofMyrmica have been used in that experiments.38 of the 64 larvae ofAnergates used became imagos. Most of the 26 lostAnergates died at the beginning of the adoption and during the metamorphosis. The females lived generally 2 or 3 days and tried, very early, to leave their native nest. The males lived 2 or 3 weeks.

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Anergates atratulus Myrmica laevinodis, 22 . bmecme Anergates Myrmica. Myrmica Anergates. Myrmica Anergates. Myrmica . 64 Anergates , 38 . 26 Anergates 2 3 . 2 3 .

     

Purification and characterization of (1→3, 1→4)-β-glucan endohydrolases from germinated wheat (Triticum aestivum)

A (13, 14)--glucan 4-glucanohydrolase [(13, 14)--glucanase, EC 3.2.1.73] was purified to homogeneity from extracts of germinated wheat grain. The enzyme, which was identified as an endohydrolase on the basis of oligosaccharide products released from a (13, 14)--glucan substrate, has an apparent pI of 8.2 and an apparent molecular mass of 30 kDa. Western blot analyses with specific monoclonal antibodies indicated that the enzyme is related to (13, 14)--glucanase isoenzyme EI from barley. The complete primary structure of the wheat (13, 14)--glucanase has been deduced from nucleotide sequence analysis of cDNAs isolated from a library prepared using poly(A)⁺ RNA from gibberellic acid-treated wheat aleurone layers. One cDNA, designated LW2, is 1426 nucleotide pairs in length and encodes a 306 amino acid enzyme, together with a NH₂-terminal signal peptide of 28 amino acid residues. The mature polypeptide encoded by this cDNA has a molecular mass of 32085 and a predicted pI of 8.1. The other cDNA, designated LW1, carries a 109 nucleotide pair sequence at its 5 end that is characteristic of plant introns and therefore appears to have been synthesized from an incompletely processed mRNA. Comparison of the coding and 3-untranslated regions of the two cDNAs reveals 31 nucleotide substitutions, but none of these result in amino acid substitutions. Thus, the cDNAs encode enzymes with identical primary structures, but their corresponding mRNAs may have originated from homeologous chromosomes in the hexaploid wheat genome.