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     

Concluding remarks

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

Identification of a high-molecular-weight subunit of glutenin whose presence correlates with bread-making quality in wheats of related pedigree

Summary The subunit composition of glutenin was analysed by SDS-polyacrylamide-gel electrophoresis using two varieties of contrasting pedigrees. Maris Widgeon, a variety of good bread-making quality, was shown to contain 2 glutenin subunits not present in Maris Ranger, a much higher yielding variety that is unsuitable for making bread. A third subunit was only found in Maris Ranger glutenin. To determine if any of these subunits are directly related to bread-making quality, 60 randomly-derived F₂ progeny from a Maris Widgeon x Maris Ranger cross were analysed for bread-making quality and for glutenin subunit composition. A strong correlation was demonstrated between the presence of one of the two subunits inherited from Maris Widgeon, and quality. This subunit (termed subunit 1 glutenin) had an approx. mol. wt. of 145,000. It was also found in Maris Freeman, a bread-making variety selected from the same cross previously made in 1962. In further crosses involving Maris Widgeon or its descendants, more bread-making varieties have been produced in the last decade at the Plant Breeding Institute, Cambridge and all but one have inherited glutenin subunit 1. The subunit has been traced back through Holdfast to White Fife, a Canadian hard spring wheat of excellent breadmaking quality. Some 67 varieties were screened for the presence of glutenin subunit 1 and it was found in 31% of them. Several unrelated varieties of good bread-making quality did not contain subunit 1 glutenin.     

Distribution and Density of Seals in Pil'tun Bay (Northeastern Sakhalin) in the Summer–Autumn Period

The results of seal counts performed during the summer–autumn period of the years 1999–2001 in Pil'tun Bay from onboard Zodiak motor boats and Mi-8 and Mi-8MTV helicopters have been analyzed. The information is presented on the density of seals in the bay. The heterogeneous distribution pattern of seals in the bay and the presence of intermittent migrations provide favorable conditions for foraging in young animals.     

Isolation of cobamides from Methanothrix soehngenii: 5-methylbenzimidazole as the α-ligand of the predominant cobamide

Methanothrix soehngenii was found to contain five different cobamides when grown on vitamin B₁₂ supplemented as well as vitamin B₁₂ free media. In both cases, it was shown by HPLC-chromatography and UV/VIS spectroscopy, that -5-methylbenzimidazolyl--cyanocobamide was the predominant cobamide, accounting for 27% and 23%, respectively, of the total corrinoid content. Vitamin B₁₂ and -5-hydroxybenzimidazolyl--cyanocobamide could also be detected in both cell batches in varying amounts. Cells grown on vitamin B₁₂ free medium contained significantly more baseless cobamides, indicating biosynthesis of cobamides.Abbreviations (5-MeBza)CNCba -5-methylbenzimidazolyl--cyanocobamide - (5-HOBza)CNCBa -5-hydroxybenzimidazolyl--cyanocobamide (factor III) - (5-MeOBza)CNCba -5-methoxybenzimidazolyl--cyanocobamide (factor III_m) - (Bza)CNCba -benzimidazolyl--cyanocobamide     

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.     

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.     

Involvement of ABA in postharvest life of miniature potted roses

Exogenous application of ABA (abscisic acid) to intact miniature potted rose plants (Rosa hybrida L.) resulted in deterioration of postharvest quality of two cultivars. Spraying with ABA increased leaf drop and accelerated flower senescence in Vanilla and Bronze, while bud drop was only induced in Bronze. Application of ABA to detached rose flowers accelerated their senescence, indicating that the observed senescence promoting effect was not a secondary response resulting from ABA-induced leaf senescence and abscission. ABA-treatment increased ethylene production in Bronze flowers, while no ethylene production was measured in flowers of Vanilla, or in the leaves of both cultivars. Pre-treatment with 1-MCP (1-methylcyclopropene) delayed ABA promoted flower senescence in Bronze, suggesting that the effect of ABA is at least partly mediated by ethylene. The senescence promoting effect of ABA on leaf drop and flower life of Vanilla flowers was not counteracted by 1-MCP pre-treatment. The cultivar Vanilla had a low ABA level at all flower stages, while ABA content of the Bronze petals was high in buds, lower in open flowers, and increased during flower senescence. An increased ABA content after ethylene treatment in Vanilla suggests that ethylene, natural or exogenous, can increase ABA levels of flowers.     

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.     

Role of cyclic adenosine-3′,5′-monophosphate in olfactory reception

The action of cyclic adenosine-3,5-monophosphate (3,5-AMP) and of substances modifying the rate of its breakdown (inhibitors and activators of phosphodiesterase) on the olfactory epithelium was investigated in frogs. The slow electrical response of the olfactory epithelium to stimulation by solutions of various substances was recorded. Cyclic 3,5-AMP and its dibutyryl derivative were found to excite the olfactory receptors effectively. Responses to these substances developed after an appreciably longer delay than responses to stimulation by solutions of odiferous substances. It is postulated that the depolarizing action of 3,5-AMP and dibutyryl 3,5-AMP is manifested only after they have penetrated inside the receptor cell through its membrane. Both 5-AMP and cyclic 2,3-AMP were ineffective. In the next series of experiments the integral receptor potential was recorded in response to short stimulation by the vapor of an odiferous substance. The duration of this potential was increased after treatment of the olfactory epithelium with phosphodiesterase inhibitors: methylxanthines or papaverine. Conversely, the negative wave of the integral receptor potential was shortened under the influence of the phosphodiesterase activator imidazole. Cyclic 3,5-AMP is considered to play the role of mediator in the mechanism of excitation of the olfactory receptor; during interaction between an odiferous substance and the receptor, adenyl cyclase is activated and the concentration of 3,5-AMP increases; this, in turn, causes depolarization of the receptor cell membrane.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 5, No. 4, pp. 415–422, July–August, 1973.     

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     

The beta1 integrin subunit is not a specific component of the costamere domain in human myocardial cells

Studies on altered integrin receptor expression during cardiac hypertrophy and heart failure requires accurate knowledge of the distributional pattern of integrins in myocardial cells. At present the general consensus is that in cardiac muscle the ₁ integrin receptor is mainly localized to the same sarcolemmal domain as vinculin at Z-band levels (costamere). Since most previous studies have been focusing on myocardial integrin distribution in lower mammals, the myocardial localization of the ₁ integrin subunit was investigated in biopsies collected from the auricle of patients undergoing a coronary bypass operation. Non-invasive serial optical sectioning was carried out by immuno-laser scanning confocal microscopy. Double-labelling for vinculin/-actinin, and the cytoplasmic domain for the ₁ integrin subunit, showed that ₁ integrin is deposited throughout both the vinculin/-actinin domains and the non-vinculin/-actinin domains. These results were supported by a semi-quantitative analysis in extended focus images of the latter preparations. Higher magnification views at the electron microscopical levels of the large, extracellular domain of the ₁ integrin subunit disclosed a pronounced labelling in the form of a dense, irregular punctuate pattern that was distributed at Z-disc domains as well as along the entire sarcolemmal area between Z-discs. Our findings show that in human, myocardial cells, the ₁ integrin receptor does not only localize to the surface membrane at the Z-disc level (costamere in cardiac muscle), but has a widespread distribution along the sarcolemma.     

Linkage of the β-Like ω-Globin Gene to α-Like Globin Genes in an Australian Marsupial Supports the Chromosome Duplication Model for Separation of Globin Gene Clusters

The structure, function, and evolutionary history of globin genes have been the subject of extensive investigation over a period of more than 40 years, yet new globin genes with highly specialized functions are still being discovered and much remains uncertain about their evolutionary history. Here we investigate the molecular evolution of the -globin gene family in a marsupial species, the tammar wallaby, Macropus eugenii. We report the complete DNA sequences of two -like globin genes and show by phylogenetic analyses that one of these genes is orthologous to embryonically expressed -globin genes of marsupials and eutherians and the other is orthologous to adult expressed -globin genes of marsupials and eutherians. We show that the tammar wallaby contains a third functional -like globin gene, -globin, which forms part of the -globin gene cluster. The position of -globin on the 3 side of the -globin cluster and its ancient phylogenetic history fit the criteria, originally proposed by Jeffreys et al. (1980), of a fossil -globin gene and suggest that an ancient chromosome or genome duplication preceded the evolution of unlinked clusters of - and -globin genes in mammals and avians. In eutherian mammals, such as humans and mice, -globin has been silenced or translocated away from the -globin locus, while in marsupials -globin is coordinately expressed with the adult -globin gene just prior to birth to produce a functional hemoglobin (_{2 2}).     

Invertebrate predator-prey body size relationships: an explanation for upper triangular food webs and patterns in food web structure?

Summary It has been suggested by Cohen and Newman (1985) that many of the patterns in published food webs can be derived from a stochastic model in which the species are arranged in a trophic hierarchy (the cascade model). We suggest that, if predators are larger than their prey, a trophic hierarchy can be generated on the basis of body size Empirical evidence from the literature shows that there is a positive relationship between predator and prey size for a range of invertebrates and that predators are usually larger than their prey. Using experimental data on an aquatic food web we show that body size can lead to the type of trophic hierarchy used in the cascade model, suggesting that many food web patterns may be a product of body size. This conclusion is discussed with respect to the limitations of the food web data and the relationship between static and dynamic models of web structure.     

T-cell receptor gene rearrangement and expression in human natural killer cells: natural killer activity is not dependent on the rearrangement and expression of T-cell receptor α, β, or γ genes

To test the hypothesis that the T-cell receptor (Tcr) gene encodes a natural killer (NK) cell receptor molecule, three human NK clones and fresh peripheral blood lymphocytes with NK activity from two patients with a CD16⁺ lymphocytosis were analyzed for rearrangements and expression of the human Tcr , , and genes. Two of the clones displayed distinct rearrangements of their Tcr and genes and expressed mature Tcr , , and l RNA. However, one of the clones and both patient samples displayed marked NK activity but failed to rearrange or express any of their Tcr genes. These findings demonstrate that human natural killer activity is not dependent on Tcr gene rearrangement and expression. In addition, they confirm previous findings concerning the lack of Tcr and gene expression in some natural killer cells. Thus, they suggest the existence of additional NK-specific recognition molecules.     

Aislamiento de antigenos cationicos de Paracoccidioides brasiliensis mediante intercambio ionico

Resumen El procedimiento de intercambio iónico empleado en este trabajo ha mostrado ser un método eficiente, sencillo y rápido, para eliminar las fracciones antigénicas aniónicas de un extracto crudo deP. brasiliensis.Su empleo permitió la obtención de un antígeno purificado que contiene algunas de las fracciones catiónicas del extracto crudo. El antígeno responsable de la formación del arco E fue identificado en el extracto purificado, mediante análisis inmunoelectroforético.     

Immunolocalization of β-(1→4) and β-(1→6)-D-galactan epitopes in the cell wall and Golgi stacks of developing flax root tissues

Summary Most cell wall components are carbohydrate including the major matrix polysaccharides, pectins and hemicelluloses, and the arabinogalactan-protein proteoglycans. Both types of molecules are assembled in the Golgi apparatus and transported in secretory vesicles to the cell surface. We have employed antibodies specific to -(16) and -(14)-D-galactans, present in plant cell wall polysaccharides, in conjunction with immunofluorescence and electron microscopy to determine the location of the galactan-containing components in the cell wall and Golgi stacks of flax root tip tissues. Immunofluorescence data show that -(14)-D-galactan epitopes are restricted to peripheral cells of the root cap. These epitopes are not expressed in meristematic and columella cells. In contrast, -(16)-D-galactan epitopes are found in all cell types of flax roots. Immunogold labeling experiments show that both epitopes are specifically located within the wall immediately adjacent to the plasma membrane. They are also detected in Golgi cisternae and secretory vesicles, which indicates the involvement of the Golgi apparatus in their synthesis and transport. These findings demonstrate that the synthesis and localization of -(14)-D-galactan epitopes are highly regulated in developing flax roots and that different -linked D-galactans associated with cell wall polysaccharides are expressed in a cell type-specific manner.     

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.     

Theoretical studies on the necessary number of components in mixtures

Summary Theoretical studies on the necessary number of components in mixtures (for example multiclonal varieties or mixtures of lines) have been performed according to yielding ability. All theoretical investigations are based upon a Gram-Charlier frequency distribution of the component means with skewness ₁ and kurtosis ₂. The selected fraction p of the best components constitutes the mixture under consideration. The same selection differential S = S (p, ₁, ₂) can be realized by different parameter values of p, ₁ and ₂. Therefore, equal yield levels of the mixture can be achieved by different selected fractions p which implies different numbers of components in the mixture. Numerical results of S = S(p) for different values of ₁ and ₂ are presented and discussed. Of particular interest are the selected fractions p which lead to a maximal selection differential S. These results on S for large populations must be reduced in the case of finite population size. For this correction term we used an approximation B = B (p, n, ₁, ₂) given by Burrows (1972) where n = number of selected components. For given parameter values of ₁, ₂ and p, the necessary number n of components can be calculated by using the condition: Burrows-correction less than a certain percentage g of S — for example with g = 0.05 or g = 0.01. For given ₁ and ₂, the number n leading to a maximal selection differential S can be regarded as necessary number of components (necessary = maximum gain of selection under the given conditions). Numerical results are given for ₂ = 0 and for eight situations which are defined by linear relations ₂ = c ₁ between skewness and kurtosis. These cases will contain all possible numerical situations for ₁ and ₂, which may be relevant for practical applications. The necessary number of components turns out to be nearly independent of the numerical value of the kurtosis ₂. The n-intervals leading to selected fractions p from 0.01 to 0.20 approximately are: 2 n 4 for g = 0.05, 6 n 20 for g = 0.01 and 11 n 40 for g = 0.005, respectively. However, percentages g less than 0.01 would be unrealistically excessive. Therefore, following the assumptions and restrictions given in this paper one may conclude that n = 20 seems to be an appropriate upper bound for the necessary number of components in mixtures.     

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.