Présence dans une population congolaise deMus (Leggada) triton Th. de femelles hétérozygotes pour une délétion caractérisée par la suppression du bras court de l'un des chromosomes X métacentriques

A sample of 12Mus (Leggada) triton Th. from the region of Bukavu (Democratic Republic of Congo) contains 5 ♂♂ and 7 ♀♀. 2N=32. All the autosomes are acrocentric. The sex-chromosomes of the ♂ are of the typeX—Y, theX beeing a big submetacentric (I.C.=0,4). Three ♀♀ possess two metacentricX, as expected. By four ♀♀, there is only one typicalX whose partner is acrocentric and as long as the long arm of a normalX. ThisX must have been arisen through the deletion of the short arm and is calledX _ddc. The statistical analysis of the sample is compatible with this pattern:

$$\begin{array}{*{20}c} { \circ \circ } \\ { + + } \\ \end{array} \begin{array}{*{20}c} {X---X = 4/9} \\ {X---X_{dc} = 4/9} \\ {X_{dc} ---X_{dc} = 1/9} \\ \end{array} \begin{array}{*{20}c} { \nearrow \nearrow } \\ { \circ \circ } \\ \end{array} \begin{array}{*{20}c} {X---Y = 2/3} \\ {X_{dc} ---Y = 1/3} \\ \end{array} $$     

Structural analysis of novel rhamnose-branched oligosaccharides from the glycophosphosphingolipids ofLeptomonas samueli

Mild alkaline hydrolysis of the glycophosphosphingolipids of the protozoanLeptomonas samueli liberated several phosphoinositol-containing oligosaccharides (PI-oligosaccharides), which were purified by high performance anion exchange chromatography. The oligosaccharides in the resulting four fractions were characterized by methylation analysis, fast atom bombardment mass spectrometry and two-dimensional nuclear magnetic resonance spectroscopy. The oligosaccharides contain the core structure Man(1–4)GlcN(1–6)-myo-inositol-1-OPO₃, and are substituted with 2mol of 2-aminoethylphosphonate per mol of oligosaccharide. The nonreducing ends of the oligosaccharides were terminated by rhamnose branched neutral and acidic xylose-containing penta-, hexa-, hepta- and octasaccharides, of which the three most abundant were shown to have the structures:

Using computer algebra to determine rate constants in biochemistry

In earlier work we have described how computer algebra may be used to derive composite rate laws for complete systems of equations, using the mathematical technique of Gröbner Bases (Bennett, Davenport and Sauro, 1988). Such composite rate laws may then be fitted to experimental data to yield estimates of kinetic parameters. Recently we have been investigating the practical application of this methodology to the estimation of kinetic parameters for the closed two enzyme system of aspartate aminotransferase (AAT) and malate dehydrogenase (MDH) (Fisher 1990a; Fisher 1990b; Bennett and Fisher, 1990): $$\begin{gathered} aspartate + \alpha - ketoglutarate\begin{array}{*{20}c} \rightharpoonup \\ \leftharpoondown \\ \end{array} glutamate + oxaloacetate \hfill \\ {\text{oxaloacetate + NADH}}\begin{array}{*{20}c} \rightharpoonup \\ \leftharpoondown \\ \end{array} malate + NAD^ + \hfill \\ \end{gathered} $$ In this paper we present a fuller (although not yet complete) analysis of the system. We show how symbolic estimates of the error behaviour of the parameters can be made, and used to identify those which are of kinetic significance. Finally we consider how metabolic control analysis can be applied directly to such a system.     

Endor characterization and D2O exchange in the \begin{array}{*{20}c} {\mathop Z\nolimits^{\begin{array}{*{20}c} + \\ . \\ \end{array} } } \\ \end{array} /{\kern 1pt} \begin{array}{*{20}c} {\mathop D\nolimits^{\begin{array}{*{20}c} + \\ . \\ \end{array} } } \\ \end{array} radical in photosystem II

The early suggestion by Lozier and Butler (Photochem. Photobiol. 17, 133–137 (1973)) that EPR Signal II arises from radicals associated with the water-splitting process in PSII has been confirmed and extended over the intervening years. Recent work has identified the Signal II radicals, \(\begin{array}{*{20}c} {\mathop D\nolimits^{\begin{array}{*{20}c} + \\ . \\ \end{array} } } \\ \end{array}\) and \(\begin{array}{*{20}c} {\mathop Z\nolimits^{\begin{array}{*{20}c} + \\ . \\ \end{array} } } \\ \end{array}\) , with plastosemiquinone cation species. In the experiments presented here we have used ENDOR spectroscopy and D₂O/H₂O exchange to characterize these paramagnets in more detail. The ENDOR matrix region, which arises from protons which interact weakly with the unpaired electron spin, is well-resolved at 4 K and at least seven resonances are apparent. A number of hyperfine couplings in the 3–8 MHz range are observed and are suggested to arise from methyl or hydroxyl protons which occur as substituents on the plastosemiquinone cation ring or from amino acid protons hydrogen-bonded to the 1,4-hydroxyl groups. Orientation selection experiments are consistent with these possibilities. D₂O/H₂O exchange shows that the D⁺/Z⁺ site is accessible to solvent. However, the exchange occurs slowly and is not complete even after 72 hours which suggests that the free radicals are functionally isolated from solvent water.     

Structure determination of the disialylated poly-(N-acetyllactosamine)-containingO-linked carbohydrate chains of equine chorionic gonadotropin

The disialylated poly-(N-acetyllactosamine)-containingO-linked oligosaccharide alditols, released by alkaline borohydride treatment of the enzymicallyN-deglycosylated β-subunit of equine chorionic chonadotropin, were purified by fast protein liquid chromatography (FPLC) on Mono Q and analysed by fast ion bombardment mass spectrometry (FAB-MS) and¹H-NMR spectroscopy. The identified oligosaccharide alditols have the following structure: $$\begin{gathered} Neu5Ac\alpha 2 - 3\left[ {Gal\beta 1 - 4GlcNAc\beta 1 - 3} \right]_{0 - 4} Gal\beta 1 - 4GlcNAc\beta 1 - 6 \hfill \\ \begin{array}{*{20}c} { \backslash } \\ { GalNAc - ol} \\ { /} \\ {Neu5Ac\alpha 2 - 3Gal\beta 1 - 3} \\ \end{array} \hfill \\ \end{gathered}$$      

Transient method for proposing the mechanisms of reactions over immobilized enzymes

The transient response method is introduced to elucidate the mechanism of reaction over immobilized enzyme. Glucose oxidation over the glucose oxidase that was immobilized on ion-exchange resin using glutaraldehyde as a linking agent is selected as an example here. The transient responses of a fixed-bed reactor to step increases and decreases in glucose, oxygen, and gluconolactone feed concentrations have been monitored and interpreted. From some responses, we have found that gluconolactone is formed in the reaction of glucose with adsorbed oxygen, while hydrogen peroxide is formed in the reaction of oxygen with adsorbed glucose. Combining all information from interpreting the responses with the literature, a mechanistic picture can be obtained as follows: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {E_{{\rm ox}} + G \to E_{{\rm red}} GL} \\ {E_{{\rm red}} GL \to E_{{\rm red}} + GL} \\ {E_{{\rm red}} + {\rm O}_2 \to E_{{\rm ox}} {\rm H}_2 {\rm O}_2 } \\ {E_{{\rm ox}} {\rm H}_2 {\rm O}_2 \to E_{{\rm ox}} + {\rm H}_2 {\rm O}_2 } \\ \end{array} $$\end{document}.     

Kinetics of ethanol inhibition in alcohol fermentation

The inhibitory effect of ethanol on yeast growth and fermentation has been studied for the strain Saccharomyces cerevisiae ATCC No. 4126 under anaerobic batch conditions. The results obtained reveal that there is no striking difference between the response of growth and ethanol fermentation. Two kinetic models are also proposed to describe the kinetic pattern of ethanol inhibition on the specific rates of growth and ethanol fermentation: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {\frac{{\mu _i }}{{\mu _0 }} = 1{\rm } - {\rm }\left( {\frac{P}{{P_m }}} \right);\alpha } \hfill & {\left( {{\rm for}\ {\rm growth}} \right)} \hfill \\ {\frac{{\nu _i }}{{\nu _0 }} = 1{\rm } - {\rm }\left( {\frac{P}{{P'_m }}} \right);\beta } \hfill & {\left( {{\rm for}\ {\rm ethanol}\ {\rm production}} \right)} \hfill \\ \end{array}$$\end{document} The maximum allowable ethanol concentration above which cells do not grow was predicted to be 112 g/L. The ethanol-producing capability of the cells was completely inhibited at 115 g/L ethanol. The proposed models appear to accurately represent the experimental data obtained in this study and the literature data.     

A directed alteration of ribonuclease specificity. Hydrolysis of polyribonucleotides containing modified cytosine bases

The action of ribonucleases on poly and oligoribonucleotides containing cytosine bases modified by methoxyamine and bisulphite was examined. Resistance of phosphodiester bonds in (Cp) _n Xp (where n 1 and X stands for A, G or U) to T₂ RNase hydrolysis was observed if substrates were modified chemically. The phenomenon formed the basis for isolation of (Cp) _n Xp blocks as an additional tool in sequence investigations. After modification of cytosine pancreatic RNase was unable to hydrolyse (Cp) _n Up blocks. Therefore the specificity of pyrimidyl RNase may be narrowed to uridyl RNase.Abbreviations cytidine modified with methoxyamine and bisulphite (5, 6-dihydro-6-sulpho-N⁴-methoxycytidine) - cytidine modified with methoxyamine (N⁴-methoxycytidine)     

Simultaneous nonlinear equations of growth

The simultaneous equations

$$\begin{gathered} \frac{{dx}}{{dt}} = \frac{{a_x }}{{k_x }}[k_x - x - f_x (y)] x \hfill \\ \frac{{dy}}{{dt}} = \frac{{a_y }}{{k_y }}[k_y - y - f_y (x)] y \hfill \\ \end{gathered}$$     

Prebiotic formation of iminothioesters. II: Addition of thiophenols to malonic nitriles

Previous kinetic studies on the addition of aliphatic thiols to activated nitriles suggest that the formation of iminothioesters (possible prebiotic precursors of thioesters) occurs through the nucleophilic addition of thiolate to the C=N group of the activated nitrile in its acidic form: $$R S^ {\ominus} + A - CH{_2} - C \equiv N {\overset {{H^ + }} \leftrightarrows} A - CH{_2} - \begin{array}{*{20}c} C \\ | \\ {SR} \\ \end{array} = NH$$ It seemed also that this addition occurs only when the pKA of the thiol is lower than the pKA of the activated nitrile. In order to test this hypothesis, and to generalize this mechanism, similar studies have been carried out using the same nitriles (A=CN; CHO), but with thiols having lower pKA (substituted thiophenols). The results of these studies, using p-aminothiophenol (pKA=6.85), p-chlorothiophenol (pKA=5.90) and p-nitrothiophenol (pKA=4.60), including the determination of rate and equilibrium constants, is presented.     

Fermentation of methanethiol and dimethylsulfide by a newly isolated methanogenic bacterium

From dilution series in defined mineral medium, a marine iregular coccoid methanogenic bacterium (strain MTP4) was isolated that was able to grow on methanethiol as sole source of energy. The strain also grew on dimethylsulfide, mono-, di-, and trimethylamine, methanol and acetate. On formate the organism produced methane without significant growth. Optimal growth on MT, with doubling times of about 20 h, occurred at 30°C in marine medium. The isolate required p-aminobenzoate and a further not identified vitamin. Strain MTP4 had a high tolerance to hydrogen sulfide but was very sensitive to mechanical forces or addition of detergents such as Triton X-100 or sodium dodecylsulfate. Methanethiol was fermented by strain MTP4 according to the following equation:

The Tryptophan Fluorescence of Tetracarbidium conophorum Agglutinin II and a Solution-Based Assay for the Binding of a Biantennary Glycopeptide

The plant lectin Tetracarbidium conophorum agglutinin II binds to glycoproteins and glycopeptides in a structurally specific manner [Animashaun et al., (1994) Glycoconjugate J. 11, 299–303]. We have characterized the steady-state and time-resolved fluorescence of the tryptophan residues of this lectin. The fluorescence (λ_ex = 295 nm, λ_em = 350 nm) decay is complex and can be described by four decay times with the following values: τ₁ = 7.4nsec, α₁ = 0.22; τ₂ = 2.9 nsec, α₂ = 0.25; τ₃ = l.0 nsec, α₃ = 0.34; τ₄ = 0.2 nsec, α₄ = 0.18. The addition of a biantennary glycopeptide $\begin{array}{*{20}c} {Gal\beta (1 \to 4)GlcNAc\beta (1 \to 2)Man\alpha (1 \to 6)\neg } \\ {Man\beta (1 \to 4)GlcNAC\beta (1 \to 4)GlcAc\beta (1 \to )\begin{array}{*{20}c} {Glu - Nh_2 } \\ | \\ {Asn} \\ | \\ {COOH} \\ \end{array} } \\ {Gal\beta (1 \to 4)GlcNAc\beta (1 \to 2)Man\alpha (1 \to 3)} \\ \end{array} $ to the lectin results in a quench and an 8 nm blue shift of the emission spectrum. The effect is saturable, and is described by an association constant of 1.8×10⁵ M^?1. The tryptophan fluorescence of Tetracarbidium conophorum agglutinin II may therefore be utilized to characterize thermodynamically the binding interactions between this lectin and complex glycoprotein.     

Contribution to the genetics of the serum β-lipoproteins in man

A study was made of the genetic behaviour of the factors Ag(x) and Ag(y) of the β-lipoproteins of human serum. It was found that these factors are controlled by a single pair of autosomal codominant genes with complete penetrance at birth. The gene frequencies were:

$$\begin{gathered} Milan . . . . Ag^x = 0,23 Ag^y = 0,77 \hfill \\ Berne . . . . Ag^x = 0,24 Ag^y = 0,76. \hfill \\ \end{gathered}$$     

The structural organization of mouse metaphase chromosomes

The binding of highly purified anti-nucleoside antibodies to mouse (Mus musculus) metaphase chromosomes was studied by an immunofluorescence technique. The chromosomal DNA was denatured by one of two selective denaturation procedures because these antibodies reacted with single stranded but not native DNA. After ultraviolet irradiation (UV), which produced single stranded regions primarily in AT rich DNA, the binding of antiadenosine (anti-A) produced a pattern of fluorescent bands similar to that produced by quinacrine (Q-bands). Additional foci of bright fluorescence were observed at the centrometric (C-band) regions, which are known to contain AT rich satellite DNA. After photooxidation, which produced single stranded regions in GC rich DNA, the binding of anti-A produced a fluorescent banding pattern similar to the R-banding pattern seen after thermal denaturation and staining with coriphosphine O. After photooxidation, R-band patterns were also obtained with anti-cytidine (anti-C) and anti-5-methylcytidine (anti-M). After either UV irradiation or photooxidation, anti-M, but not anti-C, showed intense binding to the C-band regions of mouse chromosomes. — These findings led to the following conclusions: (1) Antibody banding patterns reflect the presence of a class of AT rich, GC poor DNA in chromosome regions which show bright quinacrine fluorescence and in the regions that contain the AT rich satellite DNA. (2) The alternate, quinacrine dull regions contain a relatively GC rich class of DNA which appears to be more highly methylated than the AT rich DNA in the Q-bright bands, but not the AT rich satellite DNA in the Q-dull C-bands. (3) 5-Methylcytosine residues occur in a sequence of mouse satellite DNA that contains both adjacent pyrimidines and guanine residues. The basic repeating unit of mouse satellite DNA is known to contain the sequence 5-GAAAAATGA-3 (Biro et al., 1975). Therefore, assuming the antibodies used could detect single bases in denatured DNA, the methylated sequence in mouse satellite DNA      

The basic flow equations of electrophysiology in the presence of chemical reactions: I. Development of the equations

Starting from the basic flux equation, it is possible to obtain an integral form relating the current componentsI _i at an arbitrary pointr ₂ to the distribution of mobilities and concentrationsc _i, potential forces\(\bar \mu \), and chemical productivityp _i without any restrictive assumptions such as constant mobilities, constant field, steady state, or electrical neutrality. The equation is

$$\begin{gathered} I_i (r_2 ) = G_i (r_2 )\left[ {\Delta \bar \mu _i - \int_{r_1 }^{r_2 } {z_i } FA\left( {p_i - dc_i /dt} \right)\left( {\frac{1}{{G_i (r)}}} \right)dr} \right]; \hfill \\ G_i (r) = 1/\int_{r_1 }^r {\frac{{dr}}{{z_i^2 F^2 c_i u_i }}.} \hfill \\ \end{gathered} $$     

The Tryptophan Fluorescence of Tetracarbidium conophorum Agglutinin II and a Solution-Based Assay for the Binding of a Biantennary Glycopeptide

The plant lectin Tetracarbidium conophorum agglutinin II binds to glycoproteins and glycopeptides in a structurally specific manner [Animashaun et al., (1994) Glycoconjugate J. 11, 299–303]. We have characterized the steady-state and time-resolved fluorescence of the tryptophan residues of this lectin. The fluorescence (_ex = 295 nm, _em = 350 nm) decay is complex and can be described by four decay times with the following values: ₁ = 7.4nsec, ₁ = 0.22; ₂ = 2.9 nsec, ₂ = 0.25; ₃ = l.0 nsec, ₃ = 0.34; ₄ = 0.2 nsec, ₄ = 0.18. The addition of a biantennary glycopeptide to the lectin results in a quench and an 8 nm blue shift of the emission spectrum. The effect is saturable, and is described by an association constant of 1.8×10⁵ M^–1. The tryptophan fluorescence of Tetracarbidium conophorum agglutinin II may therefore be utilized to characterize thermodynamically the binding interactions between this lectin and complex glycoprotein.     

Kinetics of ultrafiltration hemodialysis

The expressions of Wolfet al. (1951) and Renkin (1956) for the kinetics of artificial kidneys are generalized to include the effects of filtration. IfB is the bath volume,b the relevant volume of distribution,f the filtration rate,t the time, andA ₀,B ₀,b ₀ representA, B, andb at timet=0, then the plasma concentrationA is given by

$$\frac{A}{{A_0 }} = \frac{{B_0 }}{{B_0 + b_0 }}e^{ - \frac{{\left( {B_0 + b_0 } \right)}}{{B_0 }}\frac{{D_f }}{{b_0 }}K\left( {ft} \right)t} + \frac{{b_0 }}{{B_0 + b_0 }}$$     

Vegetation gradient on the shores of Lake Nasser in Egypt

The paper, a synthesis based on data generated by our own investigation on Stipa baicalensis steppe for the period 1986–1988, deals with the relationships among biotic and abiotic factors at community ecology level. Analysis is placed on aboveground net primary production (ANPP), the energy source for livestock production process, and on accumulated temperature (5°C) (X₁), rainfall during the growing season of the steppe plants (X₂), and content of organic matter of surface soil (X₃), the abiotic variables most often used to explain variation in ANPP.The models predicting ANPP in Stipa baicalensis steppe were structured in terms of X₁, X₂, and X₃. The predictive power of the models was found to be very high, and the models were successfully validated in three cases with an independent data set.The prediction model that gave the best fitting in Stipa baicalensis steppe was% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbqfgBHr% xAU9gimLMBVrxEWvgarmWu51MyVXgaruWqVvNCPvMCG4uz3bqefqvA% Tv2CG4uz3bIuV1wyUbqee0evGueE0jxyaibaieYlf9irVeeu0dXdh9% vqqj-hEeeu0xXdbba9frFf0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea% 0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabe% aadaabauaaaOabaeqabaGaaeywaiaabIcacaWG4bGaaiykaiabg2da% 9iaaiwdacaaIYaGaaGioaiaac6cacaaIXaGaaG4maiaaikdacaaI4a% Gaey4kaSIaaGymaiaaikdacaGGUaGaaGymaiaaiMdacaaI0aGaaGio% aiaadIhadaWgaaWcbaGaaGymaaqabaGccqGHRaWkcaaI4aGaaGOmai% aac6cacaaI1aGaaG4naiaaicdacaaIXaGaaGimaiaaicdacaaIXaGa% amiEamaaBaaaleaacaaIYaaabeaakiabgUcaRiaaiwdacaaI3aGaai% OlaiaaigdacaaI5aGaaGioaiaaiEdacaWG4bWaaSbaaSqaaiaaioda% aeqaaOGaey4kaSIaaGymaiaaikdacaGGUaGaaGOnaiaaiodacaaI3a% GaaGynaiaadIhadaWgaaWcbaGaaGymaaqabaGccaWG4bWaaSbaaSqa% aiaaikdaaeqaaOGaeyOeI0IaaGOnaiaac6cacaaIXaGaaGOmaiaaiA% dacaaI1aGaamiEamaaBaaaleaacaaIXaaabeaakiaadIhadaWgaaWc% baGaaG4maaqabaaakeaacaqGGaGaaeiiaiaabccacaqGGaGaaeiiai% aabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGa% aeOmaiaabIdacaqGUaGaaeimaiaabIdacaqG3aGaaeynaiaadIhada% WgaaWcbaGaaGOmaaqabaGccaWG4bWaaSbaaSqaaiaaiodaaeqaaOGa% aeylaiaabodacaqG2aGaaeOlaiaabgdacaqG3aGaae4naiaabsdaca% WG4bWaa0baaSqaaiaaigdaaeaacaaIYaaaaOGaaeylaiaabccacaqG% ZaGaaeymaiaab6cacaqG0aGaaeinaiaabkdacaqG5aGaamiEamaaDa% aaleaacaaIYaaabaGaaGOmaaaakiaab2cacaqGYaGaaeOnaiaab6ca% caqGYaGaaeOnaiaabodacaqGZaGaamiEamaaDaaaleaacaaIZaaaba% GaaGOmaaaaaaaa!9ED0!\[\begin{gathered} {\text{Y(}}x) = 528.1328 + 12.1948x_1 + 82.5701001x_2 + 57.1987x_3 + 12.6375x_1 x_2 - 6.1265x_1 x_3 \hfill \\ {\text{ + 28}}{\text{.0875}}x_2 x_3 {\text{ - 36}}{\text{.1774}}x_1^2 {\text{ - 31}}{\text{.4429}}x_2^2 {\text{ - 26}}{\text{.2633}}x_3^2 \hfill \\ \end{gathered} \]We have also made, in detail, the analysis of the relationships among ANPP and 3 ecological factors above variables. ANPP was responsive to all of 3 ecological factors discussed in the paper. Action intensity, which has an effect upon ANPP, can be indicated by a contribution rate. The contribution rates of X₁, X₂, and X₃ were 1.069, 2.0513 and 1.8889, respectively.This paper not only discussed profoundly the relationships among ANPP and X₁, X₂, and X₃, but also studied exhaustively effects of the interactions X₁, X₂, and X₃, on ANPP.