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.     

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.     

The role of insertions, deletions, and substitutions in the evolution of R6 related plasmids encoding aminoglycoside transferase ANT-(2")

Summary In 7% of gram-negative bacteria resistance to gentamicin is mainly mediated by plasmid-encoded aminoglycoside transferase ANT-(2). The genome organization of 15 aadB plasmids (42-110 kb) was analyzed by restriction and hybridization techniques. They appeared to be IncFII-like replicons but were distinct from R6 by virtue of small substitutions in the transfer region. Aminoglycoside resistance genes aadB and aadA were located on Tn21 related elements. Only one of them was able to transpose its resistance genes mer sul aadA and aadB (Tn4000), the other elements were naturally occurring defective transposons. In some of these structures deletions were identified at the termini, at sul, aadA, mer or transposition function-insertions adjacent to aadA or mer. The mode of these rearrangements and their site-specificity were considered with respect to the evolution of the Tn21 transposon family.Abbreviations aadA (genotype) AAD-(3) (phenotype): aminoglycoside 3-adenylytransferase - aadB ANT-(2): aminoglycoside 2-adenylyltransferase - aphA APH-(3)I: aminoglycoside 3-phosphotransferase - aacA AAC-(6): aminoglycoside 6-N-acetyl-transferase - aacC AAC-(3): aminoglycoside 3-N-acetyltransferase - cat CAT: chloramphenicol-acetyltransferase - Ap ampicillin - Su sulfonamides - Tc tetracycline - Sm streptomycin - Spe spectinomycin - Hg mercury - Cb carbenicillin - Dk dibekacin - Gm gentamicin - Km kanamycin - Nm neomycin - Net netilmycin - Pm paromomycin - But butirosin - Tm tobramycin - Sis sisomycin - Cm chloramphenicol - kb kilobase     

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     

Purification and characterization of aspartate aminotransferase from developing embryos of the camel tick Hyalomma dromedarii

Aspartate transaminase (AST) activity in the camel tick Hyalomma dromedarii was followed throughout embryogenesis. During purification of AST to homogeneity, ion exchange chromatography lead to four separate forms (termed I, II, III and IV). AST II with the highest specific activity was pure after chromatography on Sephacryl S-300. The molecular mass of AST II was 52KDa for the native enzyme, composed of one subunit of 50KDa. AST II had a Km value of 0.67mM for -ketoglutarate and 15.1mM for aspartate. AST II had a pH optimum of 7.5 with heat stability up to 50°C for 15min. The enzyme was activated by MnCl₂, and inhibited by CaCl₂, MgCl₂, NiCl₂, and ZnCl₂.     

The quantitative analysis of chromosome pairing and chiasma formation based on the relative frequencies of M I configurations

Whilst reliable estimates of chiasma frequencies can usually not be obtained, the probability (b) of a chromosome arm to be bound by at least one chiasma can often be determined. In the absence of interference this probability equals (1–e ^–2), where 2 is the average chiasma frequency of the chromosome arm and the average crossover frequency or map length. In the presence of interference is shown to retain its genetic meaning as an additive metric that may describe the chromosome arm or other distinctive chromosome segment in terms of genetic recombination. It is a form of potential map length, comparable to, but numerically different from the regular map length. It is termed provisionally crossing-over potential.A chromosome with armsm andn with crossing-over potentials and will form ring bivalents with a frequency (1–e ^–2).(1–e ^–2); open bivalents with a frequency (1–e ^–2).e ^–2+(1–e ^–2).e ^–2; univalent pairs with a frequencye ^–2.e ^–2. Estimates of these frequencies yield equations from which and may be solved. In rye (Secale cereale) their ratio (q) is approximately two and differs from the mitotic arm length ratio of 1.4, indicating localization of chiasmata in the long arms.Graphs are given to show how, with constantq, the relation between the probabilitiesb _m andb _n of the two arms being bound changes with changing averageb.Data are presented on chiasma frequencies in M I, and compared with the frequencies expected in the absence of interference to give an impression of the degree of interference. Apparent fusion of chiasmata simulates interference.     

Residual motion of hemoglobin-bound spin labels and protein dynamics: viscosity dependence of the rotational correlation times

The residual motion of spin labels bound to cysteine 93 and to lysines of methemoglobin has been studied by electron paramagnetic resonance spectroscopy. To separate the influences of the solvent and the protein environment of the label fluctuations, the correlation times, , were analyzed as a function of temperature for fixed solvent viscosities, . Results show that over a wide range of viscosity the dependence of on may be empirically described by a power law ^k . The exponent k depends strongly on the location of the label on the protein surface. If one regards the spin labels as artificial amino acid side chains, characteristic values of correlation times and amplitudes of the rotational motion at the surface can be given. For =1 cP and T=297 K the correlation time of the labels bound to lysines is found to be =9 · 10^–10 s and the rotational diffusion is nearly isotropic. The spin label bound to cysteine 93 occupies a protein pocket, its rotational motion is therefore restricted. The correlation time of the label motion within a limited motion cone of semi angle =30° ± 3° is found to be =1.3 · 10^–9 s for =1 cP and T=297 K.     

Theoretical stability diagram of solvent-containing black lipid films

Recently, we have developed an analytical, semi-microscopic theory for the macroscopic behavior of a solvent-containing black lipid film subjected to an electric cross film voltage, . Here we employ the theoretical expressions derived for the disjoining pressure, _D, the film elasticity, _F, and the film tension, _F, to construct the stability diagram of the film, in the _D-. Depending on its state (_D, ), the film is stable or is prone to squeezing or bending deformations. For a monooleate film we show how the destruction of the plane film due to a periodic thickness fluctuation (squeezing) is facilitated by two mechanisms: i) lowering of _D at fixed ; ii) lowering of at fixed _D, provided that the film is in a stable state characterized by _D<–7.03×10³ dyne/cm² and >0 mV. Bending of a low tension film (single interface tension _s 0.025 dyne/cm¹) can be achieved only for >170 mV and _D > –8.7 × 10⁴ dyne/cm². Finally, we demonstrate the existence of a marginal state ( _D ⁰ , ⁰) where the film is predicted to exhibit strong fluctuations both in the squeezing and in the bending mode.     

The effect of the methyl substituent on the bioconversion of cyclohexene derivatives

Summary The absence of the methyl substituent at the 2position of the cyclohexene ring of TCHP enhances the conversion rate as well as the yields of the 3-hydroxy product obtained byStreptomyces natalensis and the 3-keto product obtained byMycobacterium smegmatis.Abbreviations TCHP 1-(2-thienyl)-3-(1-cyclohexen-1-yl)-1-propanone - TCHP-OH 1-(2-thienyl)-3-(3-hydroxyl-1-cyclohexen-1-yl)-1-propanone - TCHP-ketone 1-(2-thienyl)-3-(1-cyclohexen-1-yl-3-one)-1-propane - TMCHP 1-(2-thienyl)-3-(2-methyl-1-cyclohexen-1-yl)-propanone     

Characterization and expression analysis of CD3ɛ and CD3γ/δ in fugu, Takifugu rubripes

CD3 is an essential component of the CD3-TCR complex. In this report, we describe the cloning, characterization, and expression analysis of the CD3 and CD3/ chain genes from fugu, Takifugu rubripes. Two distinct CD3 homologue cDNAs, designated as CD3-1 and CD3-2, and a CD3/ homologue cDNA were isolated from the fugu thymus. The deduced amino acid sequences of these cDNAs exhibit conserved essential CD3 chain motifs and overall structures. RT-PCR analysis demonstrated that the CD3 and CD3/ genes were expressed in lymphoid organs (e.g. thymus, head kidney, trunk kidney and spleen), mucosal tissues (gill, skin, and intestine), and peripheral blood leucocytes (PBL). The CD3 and TCR genes were expressed only in the surface IgM^– population, which were separated from PBL using an anti-fugu IgM monoclonal antibody. In addition, in situ hybridization confirmed that CD3-expressing cells were distributed randomly in the head kidney, trunk kidney, and spleen, but in the thymus were restricted to the lymphoid outer zone and epithelioid inner zone only. Collectively, these results suggest that CD3 molecules are useful markers for the identification of T cells in teleost fish. The present study thus provides a critical step in identifying T cells in this model organism.Nucleotide sequence data reported in this paper are available in the DBJ/EMBL/GenBank databases and have been assigned the accession numbers AB166798 (CD3-1), AB166799 (CD3-2), and AB166800 (CD3/).     

A passage saturation transfer paramagnetic resonance study of the rotational diffusion of the sarcoplasmic reticulum calcium-ATPase

A study was made of the dependence on temperature of the saturation transfer ESR spectra obtained from sarcoplasmic reticulum vesicles labeled withN-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)-maleimide. When the spin-labeled preparation was heated, some change occurred that was accompanied by an increase in the spectral parametersL/L andH/H (Thomaset al. (1976).J. Chem. Phys. 65, 3006–3024). This heat-induced increase inL/L andH/H competed with the reduction in these parameters that would normally accompany a reduction in ₂, with the result that a biphasic response to increasing temperature was observed. The heat-induced perturbation was partially irreversible. Consequently, although the preparation also exhibited a biphasic response to cooling, the heating and cooling curves did not coincide. It is suggested that a heat-induced re-orientation of the nitroxide probe with respect to the membrane normal, together with the anisotropic nature of the rotational motion, could be the cause of the departure from the expected monotonic relationship between the spectral parameters and temperature.     

Medicarpin and maackiain 3-O-glucoside-6′-O-malonate conjugates are constitutive compounds in chickpea (Cicer arietinum L.) cell cultures

Summary The pterocarpan phytoalexin conjugates medicarpin 3-O-glucoside-6-O-malonate and maackiain 3-O-glucoside-6-O-malonate were isolated from cell suspension cultures of chickpea (Cicer arietinum L.) cultivar ILC 3279 and structurally elucidated. Both pterocarpan conjugates are constitutive metabolites of the chickpea cell cultures. Upon application of an elicitor from yeast to the cell cultures a substantial increase in the level of the phytoalexin aglycones medicarpin and maackiain was observed although a delayed but significantly higher rise of the conjugates also occurred. The significance of the pterocarpan conjugates for phytoalexin production is discussed.Abbreviations MeGM medicarpin 3-O-glucoside-6-O-malonate - MaGM maackiain 3-O-glucoside-6-O-malonate - MeG medicarpin 3-O-glucoside - MaG maackiain 3-O-glucoside - FGM formononetin 7-O-glucoside-6-O-malonate - BGM biochanin A 7-O-glucoside-6-O-malonate - IFR NADPH: 2-hydroxyisoflavone oxidoreductase - PTS pterocarpan synthase - IGT UDP-glucose: isoflavone 7-O-glucosyltransferase - IMT malonyl-coA: isoflavone 7-O-glucoside-6 -O-malonyltransferase - RT retention time - sh shoulder - d duplette - m multiplette - s singulette     

Proteolytic digestion of α-lactalbumin: Physiological implications

The kinetics of the partial digestion of bovine -lactalbumin (-LA) by trypsin, -chymotrypsin, and pepsin was monitored by lactose synthase activity, HPLC, and difference spectrophotometry. The relative stabilities of the various metal-bound states of -LA to trypsin and chymotrypsin at 37 and 5°C decrease in the following order: Ca(II)--LA>Zn(II), Ca(II)--LA>apo--LA. The HPLC digestion patterns of Ca(II)--LA and Zn(II), Ca(II)--LA at 5 and 37°C were similar, while the corresponding digestion patterns for apo--LA were quite different, reflecting the existence of the thermally induced denaturation states of apo--LA within this temperature region. Occupation of the first Zn(II)-binding site in Ca(II)-loaded -LA slightly alters the HPLC digestion patterns at both temperatures and accelerates the digestion at 37°C due to Zn(II)-induced shift of the thermal transition of -LA, exposing some portion of thermally denatured protein. The results suggest that the binding of Zn(II) to the first Zn(II)- (or Cu(II))-specific site does not cause any drastic changes in the overall structure of -LA. The acidic form of -LA (atpH 2.2 and 37°C) was digested by pepsin at rates similar to that for the apo- or Cu(II), Ca(II)-loaded forms by trypsin or -chymotrypsin at neutralpH. Complexation of -LA with bis-ANS affords protection against pepsin cleavage. It is suggested that the protective effects of similar small lipophilic compounds to -LA may have physiological significance (e.g., for nutritional transport).On leave from the Institute of Biological Physics, USSR Academy of Sciences, Pushchino, Moscow Region, 142292, USSR.     

Genetic characterization of a new splice variant of the β2 subunit of the voltage-dependent calcium channel

This study reports a novel splice variant form of the voltage-dependent calcium channel ₂ subunit (_2g). This variant is composed of the conserved amino-terminal sequences of the _2a subunit, but lacks the -subunit interaction domain (BID), which is thought essential for interactions with the ₁ subunit. Gene structure analysis revealed that this gene was composed of 13 translated exons spread over 107 kb of the genome. The gene structure of the ₂ subunit was similar in exon-intron organization to the murine ₃ and human ₄ subunits. Electrophysiological evaluation revealed that _2a and _2g affected channel properties in different ways. The _2a subunit increased the peak amplitude, but failed to increase channel inactivation, while _2g had no significant effects on either the peak current amplitude or channel inactivation. Other subunits, such as ₃ and ₄, significantly increased the peak current and accelerated current inactivation.     

Identification and confirmation of three neutral alleles conferring wide compatibility in inter-subspecific hybrids of rice (Oryza sativa L.) using near-isogenic lines

Wide-compatibility varieties (WCVs) are a special class of rice germplasm that is able to produce fertile hybrids when crossed to both indica and japonica subspecies. Previous studies determined Dular and 02428 as two WCVs and identified a number of QTLs as having large effects on fertility of inter-subspecific hybrids. In this study, we developed five near-isogenic lines (NILs) for three of the QTLs, f5, f6 and S5, by backcrossing and marker-assisted selection, using Dular and 02428 as the donors and Zhenshan 97 as the recipient. Three of the NILs each carried one introgressed allele, and two NILs each carried two introgressed alleles in combinations. The NILs were testcrossed to an indica tester Nanjing 11 and a japonica tester Balilla. The results showed that the f5 allele from Dular (f5-Du) is a neutral allele conferring wide compatibility, with a large effect on both pollen and spikelet fertility, and the f6 allele from Dular (f6-Du) is a neutral allele for spikelet fertility with smaller effect. The S5 allele from 02428 (S5-08) was confirmed to be a neutral allele for spikelet fertility. It is likely that f6 and S5 are the same locus as deduced by their genomic locations and effects. The results also showed that even in combination, two neutral alleles of different loci were not able to produce normal fertility hybrids in typical indica–japonica crosses. The implications of the findings in rice breeding programs are discussed.     

TROSY experiment for refinement of backbone psi and phi by simultaneous measurements of cross-correlated relaxation rates and 3,4J(H alpha HN) coupling constants

The TROSY principle has been introduced into a HNCA experiment, which is designed for measurements of the intraresidual and sequential H-C/H^N-N dipole/dipole and H-C/N dipole/CSA cross-correlated relaxation rates. In addition, the new experiment provides values of the ^3,4 J _{H HN} coupling constants measured in an E.COSY manner. The conformational restraints for the and angles are obtained through the use of the cross-correlated relaxation rates together with the Karplus-type dependencies of the coupling constants. Improved signal-to-noise is achieved through preservation of all coherence transfer pathways and application of the TROSY principle. The application of the [¹⁵N,¹³C]-DQ/ZQ-[¹⁵N,¹H]-TROSY-E.COSY experiment to the 16 kDa apo-form of the E. coli Heme Chaperon protein CcmE is described. Overall good agreement is achieved between and angles measured with the new experiment and the average values determined from an ensemble of 20 NMR conformers.     

Eco-physiological studies on Indian arid zone plants

Summary Photosynthetic characteristics of two important grasses of Indian desert have been studied. Pennisetum typhoides, an important cereal crop, known to have Kranz-type leaf anatomy and low CO₂-compensation point, shows the C-4-dicarboxylic acid pathway for photosynthetic carbon reduction. Lasiurus sindicus, a promising forage grass, has also been shown to possess, for the first time, a typical Kranz-type leaf anatomy and a very similar CO₂-fixation pattern like Pennisetum typhoides. It is remarkable that both species after short time exposure to ¹⁴CO₂ show a high labelling not only in malate but also in alanine. This may be due to the activity of an aspartic acid decarboxylase.     

Gibberellins play a role in the interaction between imidazole fungicides and cytokinins in Araceae

Imidazole fungicides such as imazalil, prochloraz, and triflurnizole and the triazole growth retardant paclobutrazol promote the shoot-inducing effect of exogenous cytokinins in Araceae, such as Spathiphyllum floribundum Schott and Anthurium andreanum Schott. The mechanism of their action could partially be based on the inhibition of gibberellic acid (GA) biosynthesis, because administration of GA₃ inhibits the phenomenon completely in S. floribundum. Not only is the suppression of GA biosynthesis involved, but also the metabolism of endogenous cytokinins is significantly altered. Although the balance between isopentenyladenine, zeatin, dihydrozeatin, and their derivatives was shifted to distinguished directions by administration of BA and/or imazalil and/or GA₃, no correlation between these changes in metabolic pathways and the number of shoots could be found. The metabolism of BA was not significantly altered by adding imazalil to the micropropagation medium of S. floribundum.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - [9R-5P]DHZ 9--d-ribofuranosyl-dihydrozeatin-monophosphate - [9R-5P]iP 6-isopentenyl-9--d-ribofuranosyladenine-monophosphate - [9R-5P]Z 9--d-ribofuranosyl-zeatin-monophosphate - [9G]BA 6-benzyl-9--d-glucopyranosyladenine - [9G]DHZ 9--d-glucopyranosyl-dihydrozeatin - [9G]iP 6-isopentenyl-9--d-glucopyranosyladenine - [9G]Z 9--d-glucopyranosyl-zeatin - [9R]BA 6-benzyl-9--d-ribofuranosyladenine - [9R]DHZ 9--d-ribofuranosyl-dihydrozeatin - [9R]iP 6-isopentenyl-9--d-ribofuranosyladenine - [9R]Z 9--d-ribofuranosyl-zeatin - BA 6-benzyladenine - DHZ dihydrozeatin - ES⁺ LC-MS/MS HPLC coupled Electrospray Tandem Mass Spectrometry - f.m. fresh mass - mT 6-(3-hydroxybenzyl)adenine - IMA imazalil - iP isopentenyladenine - NAA 1-naphthalene acetic acid - NFT Nutrient Film Technique - (OG)[9R]DHZ O--glucopyranosyl-9--d-ribofuranosyl-dihydrozeatin - (OG)[9R]Z O--d-glucopyranosyl-9--d-ribofuranosyl-zeatin - (OG)DHZ O--d-glucopyranosyl-dihydrozeatin - (OG)Z O--d-glucopyranosyl-zeatin - PAR Photosynthetic Active Radiation - PBZ paclobutrazol - PRO prochloraz - TDZ thidiazuron - TRI triflurnizole - Z zeatin     

Carbohydrate structural units in glycoproteins and polysaccharides as important ligands for Gal and GalNAc reactive lectins

Glycoproteins (gps) contain many carbohydrate epitopes or crypto-glycotopes for Gal and GalNAc reactive lectins. They are present on the cell surface and function as receptors in various life processes. Many exist in soluble or gel form and serve as biological lubricants or as barriers against microbial invasion. During the past two decades, eleven mammalian structural units have been used to express the binding domain of applied lectins. They are:F, GalNAc1 3GalNAc;A, GalNAc1 3Gal;T, Gal1 3GalNAc;I, Gal1 3GlcNAc;II, Gal1 4GlcNAc;B, Gal1 3Gal;E, Gal1 4Gal;L, Gal1 4Glc;P, GalNAc1 3Gal;S, GalNAc1 4Gal andTn, GalNAc1 Ser(Thr). ExceptL andP, all of the units can be found in glycoproteins.Tn, which is an important marker for breast/colon cancer and vaccine development, exists only inO-glycans. NaturalTn gp, the simplest mammalianO-glycan, is exclusively expressed in the armadillo salivary gland. Antifreeze gp is composed of repeating units ofT.Pneumococcus type XIV capsular polysaccharide has uniformII disaccharide as carbohydrate side chains. Asialo human ₁-acid gp and asialo fetuin provide multi-antennaryII structures. Human ovarian cyst gps, which belong to the complex type of glycoform, comprise most of the structural units. To facilitate the selection of lectins that could serve as structural probes, the carbohydrate binding properties of Gal/GalNAc reactive lectins have been classified according to their highest affinity for structural units and their binding profiles are expressed in decreasing order of reactivity. Hence, the binding relationship between glycoproteins and Gal/GalNAc specific lectins can be explored.     

A neural net capable of competitive and cooperative computation

An algorithm of learning in multilayer threshold nets without feedbacks is proposed. The net is. built of threshold elements with binary inputs. During a learning process each input vector x is accompanied by a teacher's decision ({1,...,M}). The pairs (x[n], [n]) appear in successive steps independently according to some unknown stationary distribution p(x,). The problem of learning of a threshold net has been decomposed to a series of problems of learning of the threshold elements. The proposed learning algorithm of the threshold elements has a perceptron-like form. It was proven that a decision rule of the threshold net stabilizes after a finite number of steps. For definite classes {p(x, )} _* ^K of distributions p(x,), an optimal decision rule stabilizes after a finite number of steps. These classes {p(x, )} _* ^K also contain distributions describing learning processes with perturbations.