Diversity of the mouse T cell receptor Cγ1 gene: structural analysis in C57BL/Ka

We have isolated an unusual T cell receptor chain cDNA clone (7.1) from a library made from RNA derived from adult thymus of C57BL/Ka mice. This cDNA clone corresponds to the appropriately processed C1 constant region exons preceded by 1.5 kb of J-C1 intron. The 7.1 coding region is extremely homologous to the C1 gene of BALB/c mice, differing at the protein level by a single deletion (alanine 139) and a single substitution. This latter change eliminates the sole N-linked sugar attachment site, providing a basis for strain-specific glycosylation patterns. The J-C1 intronic region contains two DNA segments (termed J1 and J2) that are highly reminiscent of joining (J) segments; both have potentially functional recombination and donor splice sequences flanking an open reading frame. Northern analysis suggests that 7.1 may be derived from a large, variable region-containing precursor.     

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.     

Effects of transforming growth factor β, tumor necrosis factor α and interferon γ on pancreatic islet β-cell responsiveness to transforming growth factor α

The insulin-producing pancreatic islet -cell, characterized by low proliferative potential, is normally not responsive to the polypeptide epidermal growth factor (EGF) or its homolog transforming growth factor (TGF-). Since EGF receptors in other tissues can be up-regulated by other growth factors and by cytokines, we have in this paper investigated whether such a -cell responsiveness to TGF-, or EGF, can be conferred by co-culture with interferon (IFN-), tumor necrosis factor (TNF-) or transforming growth factor (TGF-) in various combinations. To this end, fetal rat pancreatic islets enriched in -cells were isolated and cultured for 3 days with or without 200 pM or 20 nM TGF-. It was found that neither of these TGF- concentrations affected -cell mitogenesis, insulin content or insulin secretion. However, IFN- (1000 U/ml) evoked a modest stimulation of -cell replication, while suppressing insulin secretion and leaving the islet insulin content unaltered. TNF- (1000 U/ml), on the other hand, affected none of these parameters either alone or in any combination with TGF- or IFN-. However, when TNF- or IFN-, either alone or in combination, were combined with the cytokine interleukin-1, this resulted in islet disintegration, whereas the latter cytokine alone did not exert any gross necrotic changes evident by light microscopy. TGF- (500 pM) stimulated insulin secretion but did not influence islet insulin content or -cell mitogenesis either alone or in combination with TGF- (200 pM or 20 nM). In no instance could any mitogenic or secretory response to low or high concentrations of TGF- be conferred by IFN-, TNF- or TGF- whether used alone or in combinations. Hence, responsiveness to TGF- or EGF in the -cell obviously cannot be achieved by any of these peptides.Abbreviations EGF epidermal growth factor - IFN- interferon - TGF- transforming growth factor - TGF- transforming growth factor - TNF- tumor necrosis factor      

Potentiating vanadium-evoked glucose metabolism by novel hydroxamate derivatives

L-glutamic acid () monohydroxamate (L-Glu()HXM) enhances the insulinomimetic activity of vanadium ions both in vitro and in vivo. Based on this ligand as a lead compound, and in order to delineate molecular features relevant to its anti-diabetic potential, 14 related derivatives, including short peptides, were synthesized by solution as well as by solid phase methodologies. In addition, hydroxamate derivatives of (+) pantothenic acid and D-biotin were prepared. The vanadium binding capacity of the hydroxamates synthesized was apparent, yet each had a different ligand-ions stoichiometry. The in vitro lipogenic potency of several compounds toward rat adipocytes was demonstrated. Thus, vanadium complexes of L-Gln()HXM, L-Glu()HXM-Gly, L-Aad()HXM, di-Glu-,-HXM and of (+) pantothenic acid hydroxamate exhibited 82, 79, 76, 39 and 39% of maximal insulin activity, respectively. L-Aad()HXM, L-Glu()HXM-Gly and (+) pantothenic acid hydroxamate – by themselves – were found to possess 24, 14 and 10% of maximal insulin activity, respectively. In vivo potency, however, of L-Gln()HXM vanadium complex in streptozocin-treated rat diabetic model was less apparent.     

Conformational transmission in ATP synthase during catalysis: Search for large structural changes

Escherichia coli ATP synthase has eight subunits and functions through transmission of conformational changes between subunits. Defective mutation at Gly-149 was suppressed by the second mutations at the outer surface of the subunit, indicating that the defect by the first mutation was suppressed by the second mutation through long range conformation transmission. Extensive mutant/pseudorevertant studies revealed that / and / subunits interactions are important for the energy coupling between catalysis and H⁺ translocation. In addition, long range interaction between amino and carboxyl terminal regions of the subunit has a critical role(s) for energy coupling. These results suggest that the dynamic conformation change and its transmission are essential for ATP synthase.     

Synergistic effects of TGIF and interferonγ (IFN-γ) on tumor cell growthTGIF and IFN-γ

Interferon- (IFN-) and tumor growth inhibitory factor (TGIF) were inducedin vitro in the supernatant from mixed culture of human peripheral blood mononuclear cells (PBMC) and OK-432. TGIF activity was determined by growth inhibition of a human gastric adenocarcinoma cell line, MK-1 cells, and IFN- activity was measured by radioimmunoassay. The production of TGIF and IFN- was time-dependent, reaching its maximum around 48 hrs. Although there was no significant correlation between TGIF production and IFN- production, combination of a subthreshold concentration of recombinant IFN- (rIFN-) and TGIF induced significant growth inhibition of MK-1 cells. This fact indicates that the effects of rIFN- and TGIF are synergistic. The antiproliferative effect of these cytokines are highly species-specific, and their synergistic effects were also species-specific. rIFN--sensitive and -resistant clones were successfully established from the original MK-1 cell line; those clones are both sensitive to TGIF. Synergistic antiproliferative effects were found when the rIFN--sensitive clone, but not the resistant clone, was used as a target, suggesting that the synergistic effects require the target cells' sensitivity to IFN-. These results indicate that the synergistic effects of TGIF and IFN- may produce a clinical antitumor action in cancer patients receiving OK-432 administration.     

Carotenoid pigments of Sorangium compositum (Myxobacterales) including two new carotenoid glucoside esters and two new carotenoid rhamnosides

Summary The carotenoid pigments of the myxobacterium Sorangium compositum were analyzed by chromatographical and chemical techniques and by visible, infra red, and mass spectroscopy. Besides -carotene, neurosporene, torulene, lycopene, and 1,2-dihydro-1-hydroxy--carotene, four new carotenoid glycosides were found. These pigments were identified as 1,2-dihydro-1-hydroxy-torulene glucoside ester (I), 1,2-dihydro-3,1-dihydroxy-torulene glucoside ester (III), 1,2-dihydro-1-hydroxy-torulene rhamnoside (II), and 1,2-dihydro-3,1-dihydroxytorulene rhamnoside (IV).Fifth communication on the carotenoids of myxobacteria. Fourth communication see Arch. Mikrobiol. 76, 364–380 (1971).     

Gamma carbonic anhydrase like complex interact with plant mitochondrial complex I

We report the identification by two hybrid screens of two novel similar proteins, called Arabidopsis thaliana gamma carbonic anhydrase like1 and 2 (AtCAL1 and AtCAL2), that interact specifically with putative Arabidopsis thaliana gamma Carbonic Anhydrase (AtCA) proteins in plant mitochondria. The interaction region that was located in the N-terminal 150 amino acids of mature AtCA and AtCA like proteins represents a new interaction domain. In vitro experiments indicate that these proteins are imported into mitochondria and are associated with mitochondrial complex I as AtCAs. All plant species analyzed contain both AtCA and AtCAL sequences indicating that these genes were conserved throughout plant evolution. Structural modeling of AtCAL sequences show a deviation of functionally important active site residues with respect to CAs but could form active interfaces in the interaction with AtCAs. We postulate a CA complex tightly associated to plant mitochondrial complex.     

Effect of nitrogen on thiocyanate content of Brassica oleracea var. acephala leaves

An experiment was carried out to study the effect of nitrogen fertilizer application levels (0, 47, 94 and 188 kg N/ha) on thiocyanate contents of petioles and lamina of two Brassica oleracea L. var. acephala varieties (Thousand-headed kale and Georgia collards).The results showed that N application significantly decreased thiocyanate contents of both laminae and petioles. Applying 47, 94, 188 kg N/ha reduced thiocyanate of laminae and petioles by 26, 41 and 52% and 2, 9 and 39%, respectively. The results also showed that thiocyanate of leaves from Thousand-headed kale was significantly higher than that of Georgia collards. Lamina and petiole thiocyanates of Georgia collards were 79% and 83% of those of Thousand-headed kale, respectively.     

The human genes for the α and γ subunits of the mast cell receptor for immunoglobulin E are located on human chromosome band 1823

The receptor with high affinity for immunoglobulin E (FcERI) is a key molecule in triggering the allergic reaction. It is tetrameric complex of one subunit, one subunit, and two disulfide-linked subunits. This receptor is present exclusively on mast cells and basophils. Molecules identical to the subunit of FcRI also form cell surface complex with other Fc receptors such as mouse FcRIIa in macrophages and most probably with human FcRIII (CD16) in natural killer (NK) cells. Here we show by in situ hybridization that the human genes for the (FCER1A) and subunits (FCER1 G) of FcERI and the gene for FcRIII (FCGR3, CD16) are located on human chromosome band 1823.     

The chloroplast ATP synthase: Structural changes during catalysis

This article summarizes some of the evidence for the existence of light-driven structural changes in the and subunits of the chlorplast ATP synthase. Formation of a transmembrane proton gradient results in: (1) a change in the position of the subunit such that it becomes exposed to polyclonal antibodies and to reagents which selectively modifyLys109; (2) enhanced solvent accessibility of several sulfhydryl residues on the subunit; and (3) release/ exchange of tightly bound ADP from the enzyme. These and related experimental observations can, at least partially, be explained in terms of two different bound conformational states of the subunit. Evidence for structural changes in the enzyme which are driven by light or nucleotide binding is discussed with special reference to the popular rotational model for catalysis.     

Basic carboxyl groups of hemoglobin S: Influence of oxy-deoxy conformation on the chemical reactivity of Glu-43(β)

The -carboxyl groups of Glu-43() and Glu-22() of hemoglobin-S (HbS), two intermolecular contact residues of deoxy protein, are activated by carbodiimide atp H 6.0. The selectivity of the modification by the two nucleophiles, glycine ethyl ester (GEE) and glucosamine, is distinct. Influence ofN-hydroxysulfosuccinimide, a reagent that rescues carbodiimide-activated carboxyl (O-acyl isourea) as sulfo-NHS ester, on the overall selectivity and efficiency of the coupling of Glu-22() and Glu-43() with nucleophiles has been investigated. Sulfo-NHS increases the extent of coupling of nucleophiles to HbS. The rescuing efficiency of sulfo-NHS(increase in modification) with GEE and galactosamine as nucleophiles is 2.0 and 2.8, respectively. In the presence of sulfo-NHS, the extent of modification of a carboxyl group is a direct reflection of the extent to which it is activated (i.e., the protonation state of the carboxyl group). The modification reaction exhibits very high selectivity for Glu-43() with GEE and galactosamine (GA) in the presence of sulfo-NHS. From the studies of the kinetics of amidation of oxy-HbS at its Glu-43() (i.e., chemical reactivity) as a function of thepH in the region of 5.5–7.5, the apparentpKa of its -carboxyl group has been calculated to be 6.35. Deoxygenation of HbS, nearly doubles the chemical reactivity of Glu-43() of HbS atpH 7.0. It is suggested that the increased hydrophobicity of the microenvironment of Glu-43(), which occurs on deoxygenation of the protein, is reflected as the increased chemical reactivity of the -carboxyl group and could be one of the crucial preludes to the polymerization process.     

Gamma-tubulin colocalizes with microtubule arrays and tubulin paracrystals in dividing vegetative cells of higher plants

Summary The distribution of -tubulin throughout cell division is studied in several taxa of higher plants. -Tubulin is present along the whole length of microtubules (Mts) in every cell stage-specific Mt array such as the preprophase band, the preprophase-prophase perinuclear Mts, the kinetochore Mt bundles, the phragmoplast, and the telophase-interphase transition Mt arrays. -Tubulin follows with precision the Mt pattern, being absent from any other, Mt-free, cell site. In cells treated with anti-Mt drugs, -tubulin is present only on degrading or on reappearing Mt arrays, while it is totally absent from cells devoid of Mts. -Tubulin is also present in tubulin paracrystals, which are formed in colchicine-treated cells. These observations support the view that in higher plants -tubulin may not be a microtubule-organizing-center-specific protein, but it may play a certain structural and/or functional role being related to - and -tubulin.Abbreviations Mt microtubule - MTOC microtubule-organizing center - PPB preprophase band     

Analysis of interferon-gamma resistant mutants that are possibly defective in their signaling mechanism

Summary Our previous observations indicated that mutants partially resistant to IFN-y cytotoxicity were defective in the induction of indoleamine 2,3-dioxygenase, (IDO). Two mutants highly resistant to IFN- were isolated following a second round of mutagenesis. The resistance to IFN- was inversely correlated with the inducibility of IDO in these mutants. Moreover, several other IFN- responsive genes, including those encoding 2-5A synthetase, GTP cyclohydrolase and HLA-DR, were also differentially altered in their expression upon INF- treatment. IFN-y receptor gene expression was not changed nor was the binding of the receptor to IFN-. Southern blot analysis failed to reveal any significant abnormality in the IDO gene structure in these mutants. We therefore suggest that these mutants are defective in the IFN- signaling pathway and will be useful in further analysis of the biochemical mechanism of IFN- activated gene expression in target cells.     

Immunocytochemical analysis of phosphatidylinositol-specific phospholipase C in PC12 cells: predominance of the δ isoform during neural differentiation

The rat pheochromocytoma PC12 cell line, which differentiates into sympathetic neurons under nerve growth factor (NGF) treatment, contains at least three phosphoinositidase C (PIC) isozymes, PIC , PIC , PIC . These isozymes have been previously shown to display a different subcellular localization. To determine whether or not NGF induces changes in the presence and/or distribution of PIC isozymes during PC12 neural differentiation, studies were carried out by means of in situ immunocytochemistry. After NGF administration the proliferative activity was progressively reduced to very low levels, as measured by bromodeoxyUridine incorporation, and a neuron-like morphology was displayed by almost all cells. In unstimulated PC12 cells, PIC was detected in the nucleus whereas PIC was only cytoplasmic; PIC was found in both cell compartments. In cells treated with NGF for 3 days, neural processes extended to twice the diameter of the cell body; the isoform was concentrated near the nucleus, while the immunoreactivity of the form remained constant and the form was increased. After 10 days of treatment with NGF, PIC was hardly detectable and PIC immunostaining was considerably decreased. On the contrary, PIC progressively increased and, after 14 days of NGF exposure, fully differentiated cells displayed an intense labelling of cell body and neurites. In the same cells, PIC and PIC were almost negative. These results suggest that NGF dependent neural differentiation is related to the selective down regulation of PIC and and the increase of PIC isozyme associated with the decrease of cell proliferation.     

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.     

The partial amino acid sequence of a murine Ia molecule

Eleven of the amino terminal 14 amino acid residues have been assigned in the chain of the murine I-C^d subregion molecule. The murine chain shows no homology with P29 (the putative human chain equivalent), the chain of guinea pig Ia. 4, 5, or the murineI-A subregion chain.     

β-Glucuronidase activity in human T and B lymphocytes and the Tμ and Tγ subpopulations

Summary The -glucuronidase staining characteristics of isolated T cell populations and the T and T enriched fractions derived of them were studied. T lymphocytes were obtained from purified T lymphocytes by ox-IgG rosette sedimentation. The rosette-forming cells in the pellet were referred to as T lymphocytes, whereas the lymphocytes in the interface were referred to as T depleted or T lymphocytes. B cells were studied on rosetted mononuclear cells with either mouse erythrocytes or with Staphylococcus Aureus (Cowan I) bacteria, after a preceeding polyvalent anti-human Ig treatment of the cells. While B cells showed mostly no reactivity, T and T cells were respectively characterised by a dot-like and granular pattern of reactivity. These findings are in agreement with those observed by others after -naphthyl-acetate esterase or acid phosphatase staining. Within the T lymphocyte fraction, the T non-, non lymphocytes seemed to have a granular pattern of reactivity. The same staining pattern was found in non-B, non-T lymphocytes.     

Structural relatedness ofκ-casein and fibrinogenγ-chain

Summary -Caseins, involved in the milk clotting process, and human fibrinogen-chain, involved in the blood clotting process, show structural similarities. Several long-casein sections, together corresponding to 80% of the whole protein molecule, have their counterparts in the-chain of fibrinogen, in that 31-42% of the amino acid residues occupy identical positions. The section of-casein which contains the chymosin-sensitive bond has a counterpart not only in the but also in the B-chain of fibrinogen. Furthermore, the secondary structures of the-caseins and of the-chain predicted according to the method of Chou and Fasman present several common features.41th communication on caseins.     

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.