bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the haemocyte population of the mosquito, Culex quinquefasciatus, following infection with the filarial parasite, Wuchereria bancrofti
Authors: Paily K. P. , Abidha  , Kumar B. Agiesh , Balaraman K.
Published: March 2005

Abstract.  The mosquito Culex quinquefasciatus Say (Diptera: Culicidae) is the vector of the filarial parasite Wuchereria bancrofti (Cobbold) (Spirurida: Onchocercidae), which causes human bancroftian filariasis. Information on the mosquito humoral response against the filarial parasite during the process of its infection and development is important, as it decides the vector competence of the mosquito. Visible changes in the haemocyte population of mosquito, if any, will be an indicator of the possible humoral factors. The present study was aimed at investigating changes in the populations of various types of haemocytes of Cx. quinquefasciatus following infection with W. bancrofti. On day 2 post‐feeding on microfilaraemic blood, the haemolymph perfusate of infected mosquitoes with L1 stage of the parasite showed 44.1% granulocytes, 42% prohaemocytes and 13.9% plasmatocytes, whereas that of the control mosquitoes fed on amicrofilaraemic blood showed 63.4% plasmatocytes, 22.2% prohaemocytes and 14.4% granulocytes. Differences in the population numbers of haemocyte types between the infected and control were significant (P > 0.05). However, the mosquitoes examined on day 6 post‐feeding, when the parasite was in L2 stage, did not show any such changes. But, similar changes reappeared on day 12 in mosquitoes with L3 stage of the parasite. The observed haemocyte population changes indicate the possibility of some amount of humoral immune response, through the production of certain immune molecules, in Cx. quinquefasciatus infected with W. bancrofti. The nature and exact role of such a response on the filarial parasite development need further investigation.
Morphological variability and genetic identity in Rhinoestrus spp. causing horse nasal myiasis
Authors: Otranto D. , Milillo P. , Traversa D. , Colwell D. D.
Published: March 2005

Abstract.  Larvae of Rhinoestrus purpureus (Brauer) and Rhinoestrus usbekistanicus Gan (Diptera: Oestridae) cause nasal myiases of equids. During a recent epidemiological survey in southern Italy some morphological and taxonomical doubts arose concerning the identification of Rhinoestrus third stage larvae on the basis of the features of the posterior spiracles and the distribution of dorsal spines on the third segment. Four different morphotypes were retrieved: R. usbekistanicus‐like, R. purpureus‐like and two morphotypes with shared features. The genes encoding for the mitochondrial cytochrome oxidase I (COI) and for the ribosomal subunits 16S and 28S of the four morphotypes of Rhinoestrus were investigated to determine whether they belonged to a single taxon or they displayed genetic differences indicative of more than one species. The three genes showed a very low level of sequence variation (COI 0–0.43%, 16S 0–1.45%, 28S 0–0.23%) falling within the intraspecific ranges previously described for Oestridae species. Finally, the peritreme features and the spinulation of the third segment of the four morphotypes examined could not be used to differentiate the two species.
A prospective evaluation of the Essen titanium stapes prosthesis*
Authors: Dost P. , Arweiler‐Harbeck D. , Jahnke K.
Published: March 2005

Objectives:  This is the first clinical trial to evaluate the suitability of a new titanium stapes prosthesis, which we developed jointly with the Kurz Company (Dußlingen).

Design:  In a prospective clinical study, patients with otosclerosis underwent stapes surgery using our new titanium stapes prosthesis during a period of 14 months. One year after surgery pre‐ and postoperative audiograms were performed and all patients participated in a structured interview.

Setting:  Tertiary otorhinolaryngological university department

Participants:  Of 49 patients with otosclerosis, entering the study, two patients were excluded, because they were not located any more.

Main outcome measures and results:  All patients experienced a hearing improvement of 21 dB on average except one patient. Sixty percentage of patients achieved a reduction of the air–bone gap to less than 10 dB and 31% of patients having their air–bone gap closed to within 20 dB – averaged across 0.5, 1.0, 2.0 and 4 kHz. The hearing level improved significantly in the air and in the bone conduction thresholds.

Conclusions:  This paper presents our first ‘1 year postimplantation’ results of our titanium stapes prosthesis. We consider the development of this implant to be beneficial. The results confirm significant improvement in hearing status and tinnitus levels.
Quality of life and voice following endoscopic resection or radiotherapy for early glottic cancer
Authors: Loughran S. , Calder N. , MacGregor F.B. , Carding P. , MacKenzie K.
Published: March 2005

Objectives:  To assess whether proposed voice and quality of life (QoL) outcome measures were likely to be acceptable to patients previously treated for early glottic cancer by either radiotherapy or endoscopic resection, as well as looking for differences in QoL and voice between treatments.

Design:  Questionnaire‐based cohort study.

Setting:  Secondary care, three centres.

Participants:  All patients treated for T1a or in situ glottic carcinoma between 1997 and 2003. Fifty‐three patients were identified; those who had undergone salvage surgery or radiotherapy were excluded. A proportion refused to participate or could not be contacted and two patients had died of unrelated causes. Thirty‐six patients completed the trial with 18 from each treatment arm.

Main outcome measures:  Quality of voice as assessed by three questionnaires, Voice Handicap Index (VHI), Vocal Performance Questionnaire (VPQ), Voice Symptom Score (VoiSS) and perceptual analysis of voice by Grade, Roughness, Breathiness, Asthenia and Strained (GRBAS) assessment of vocal recordings. Quality of life as assessed by the Hospital Anxiety and Depression Scale (HADS), University of Washington Quality of Life Questionnaire (UW‐QoL), and the Functional Assessment of Cancer Therapy (FACT) questionnaire.

Results:  All patients included in the trial were able to complete the questionnaires; however, 19% required assistance of some kind. GRBAS assessment showed no difference between groups for any criteria. All QoL questionnaires gave equivalent good scores. All of the voice questionnaires showed no statistical difference between groups except for the emotional subscale of the VoiSS which showed a significantly better score for the radiotherapy arm (P = 0.04).

Conclusion:  All outcome measures were applicable and acceptable to the patient group. Overall QoL and voice appears similar despite treatment arm, apart from the emotional subscale of the VoiSS. A randomized controlled trial is required to further assess this question.
Dephosphorylation of Pyrimidine Nucleotides in the Soluble Fraction of Homogenates from Normal and Regenerating Rat Liver
Authors: Fritzson P.
Published: March 2005

The dephosphorylation of the pyrimidine nucleotides UMP, CMP, dUMP, dCMP, and dTMP was determined in the soluble fraction of homogenates from normal rat liver and from regenerating liver during an 8‐day period after partial hepatectomy. The dephosphorylations were assayed at optimal pH in the presence of optimal concentrations of Mg++ ions and substrate. β‐Glycerophosphate was included among the substrates for measurement of non‐specific phosphatase activity. The intracellular origin of the enzymes was investigated by determining the rate of their appearance in the soluble fraction during homogenization and by estimating the rate at which the lysosomes were disrupted.

The results showed that the dephosphorylation of the deoxyribonucleotides was mainly due to non‐specific acid phosphatase activity. This enzyme and the alkaline phosphatase activity were found to be localized in the soluble space of the liver cell. The dephosphorylation of the ribonucleotides was due largely to a specific 5′‐nucleotidase. The enzyme was adsorbed or loosely bound to some sedimentable cell constituent at the time of cell disruption, but it was quantitatively released into the soluble fraction during 2 minutes homogenization.

During liver regeneration the acid and alkaline phosphatase activities showed slight variations which could not be related to the growth rate of the liver. In contrast, the 5′‐nucleotidase activity showed distinct, cyclic variations which were inversely related to the growth rate. The variations in the 5′‐nucleotidase activity were strikingly similar to the activity variations of uracil reductase and N‐carbamoyl‐β‐alanine amidohydrolase observed previously in regenerating liver.
Biosynthesis of Aristolochic Acid
Authors: Schütte H. R. , Orban U. , Mothes K.
Published: March 2005

Some Aristolochia species were investigated for the presence of aristolochic acid and magnoflorine. In all cases these two compounds were found in the roots and rhizomes of the plants,

[4‐14C]‐Tetrahydropapaverine · HCl feeding to Aristolochia sipho gave no radioactive aristolochic acid I. Feeding of [4‐14C]‐norlaudanosoline‐HCl yielded radioactive aristolochic acid I. The carboxyl group contained 69% of the radioactivity.
Synthèse du poly U par la RNA polymérase avec l'acide octoadénylique (hepta adénylyl‐(3′,5′)‐adénosine) comme matrice
Authors: Hayes D. H. , Cukier R. , Gros F.
Published: March 2005

The octoadenylic acid (Ap)7A serves as a template for poly U synthesis by Escherichia coli RNA polymerase. Two types of polymerisation reaction can be observed by varying the divalent cation concentration in the reaction mixture. High divalent cation concentrations (4–6 × 10−3 M MnCl2) permit a limited poly U synthesis which stops when the quantity of UTP polymerised corresponds to approximately 2 moles per mole of template A. When reaction is carried out at 27° polymerisation stops completely after the plateau level of 2 U/A is reached but at 37° it continues slowly beyond this point. Addition of template to an incubation mixture in which poly U synthesis has stopped causes reaction to start again, and to continue to a new plateau corresponding to polymerisation of 2 moles of UTP per mole of additional template A. These results show that at high divalent cation concentrations poly U synthesis stops because the template is consumed, probably by its immobilisation in a complex of the type poly A–2 poly U. In media containing low concentrations of divalent cations (10−3 M MnCl2) poly U synthesis is not limited by the amount of template used. Under these conditions the template functions catalytically. A biphasic incorporation curve is observed with a small reduction in the reaction rate at a point corresponding to the polymerisation of 2–3 moles of UTP per mole of template A. Beyond this point reaction continues at a linear rate for long periods and incorporations of up to 20 moles of UTP per mole of template A have been observed.

The average chain length of the poly U synthesised in the presence of high or low divalent cation concentrations varies between 60 and 160 residues i.e. between 10 and 20 times that of the template. Some evidence has been obtained indicating the progressive elongation of poly U chains as a function of the duration of synthesis but the maximum variation in chain length observed was only twofold.

Sedimentation analysis of the reaction products present in incubation mixtures containing both high and low concentrations of divalent cations shows that no significant amount of poly U is free at any time. The poly U is found in fast sedimenting (> 100 S) complexes dissociable by removal of divalent cations or by sodium dodecyl sulphate treatment. Both procedures liberate poly U with a sedimentation coefficient of approximately 10 S.

An interpretation of the effects of divalent cation concentration on the type of reaction catalysed by RNA polymerase is proposed.
Regulation der Biosynthese der aromatischen Aminosäuren in Saccharomyces cerevisiae
Authors: Lingens F. , Goebel W. , Uesseler H.
Published: March 2005

We have studied the repression of the first enzymes of the main branch and the pathways after the branchpoint in the aromatic biosynthesis of Saccharomyces cerevisiae. Anthranilate synthetase is repressed by l‐tryptophan and prephenate dehydratase by l‐phenylalanine. 3‐Deoxy‐d‐arabinoheptulosonic acid 7‐phosphate (DAHP) synthetases are not repressed by l‐phenylalanine, l‐tyrosine and l‐tryptophan, chorismate mutases are repressed neither by l‐phenylalanine nor by l‐tyrosine, and prephenate dehydrogenase shows no repression by l‐tyrosine. l‐Tryptophan exhibits an induction of the chorismate mutase. Besides chorismate mutase is activated by l‐tryptophan. l‐Phenylalanine exhibits an induction and also an activation of the prephenate dehydrogenase. By simultaneous addition of l‐tryptophan, l‐phenylalanine, and l‐tyrosine p ‐aminobenzoic acid was accumulated and the production of p ‐aminobenzoate synthetase was induced. The tyrosine‐sensitive and phenylalanine‐sensitive isoenzymes of DAHP synthetase belong to the V‐system of the allosteric enzymes. Chorismate mutase and prephenate dehydrogenase are members of the K‐system.

In an earlier publication we have discussed the feedback inhibition of the described enzymes. In this paper we discuss the whole events of the regulation phenomena in Saccharomyces cere‐visiae. We also considered the degradation of l‐tryptophan, l‐phenylalanine, and l‐tyrosine to tryptophol, phenylethanol, and tyrosol respectively in connection with the regulatory events.
Comparison of IgG and IgM Antibodies Specific for Uridine
Authors: Jaton J.‐C. , Ungar‐Waron H. , Sela M.
Published: March 2005

Uridine‐specific IgG and IgM antibodies, obtained by immunization of rabbits with a uridylated synthetic polypeptide, were isolated and purified by the use of a uridine‐acetyl cellulose conjugate as immunosorbent. The IgM antibodies were separated from the IgG antibodies by gel filtration on Sephadex G‐200. Both antibody preparations were pure by ultracentrifugation and immunoelectrophoresis criteria. The precipitating activities of IgM and IgG antibodies were similar on a weight basis, although the equivalence zone in the case of IgM antibody is broader. In spite of its inability to precipitate the homologous antigen, the reduced alkylated IgM subunits were still able to inhibit specifically the homologous precipitation in the U‐pAla — pLys — IgG antibody system. The average association constants for uridine of both IgG and IgM antibodies, measured by the equilibrium dialysis technique, were low and of a similar order of magnitude.

The complement fixing ability of purified IgM and IgG anti uridine antibodies upon reaction with the homologous antigen displayed significant differences: low complement fixation activity was found in the IgM fraction either at 4° or at 37°, while a high activity was found in the IgG fraction at both temperatures. The IgM fraction lost all of its ability to fix complement when the macroglobulin was reduced and carboxymethylated. PCA reaction, using a highly immuno‐specifically purified 19 S anti‐uridine antibody, was found to be negative when assayed up to an amount of 100 μg.
Thioredoxin 2: Cleavage with Cyanogen Bromide
Authors: Holmgren A. , Reichard P.
Published: March 2005

A simple and highly reproducible method for the preparation of thioredoxin from Escherichia coli B was worked out.

On treatment with cyanogen bromide thioredoxin was cleaved into two peptides which were separated by chromatography on Sephadex G‐50. The smaller peptide (peptide B) contained 37 amino acids and represented the N‐terminal fragment of thioredoxin, while the larger peptide (peptide A) contained the remaining 71 or 72 C‐terminal amino acids. The cystine and tryptophan residues of thioredoxin were found in peptide B.

Both peptides were characterized with respect to amino acid composition and were studied by spectrofluorimetry. The increase in quantum yield of the tryptophan emission resulting from the reduction of the disulfide bridge of peptide B was considerably smaller than the corresponding increase resulting from the reduction of the disulfide bridge of thioredoxin [1].

Peptide B was not reduced by TPNH and thioredoxin reductase and showed no activity in the reduction of cytidine diphosphate with ribonucleoside diphosphate reductase from Escherichia coli.
The Role of Phosphatidate Phosphohydrolase in Glyceride Biosynthesis
Authors: Smith M. E. , Sedgwick B. , Brindley D. N. , Hübscher G.
Published: March 2005

Glyceride biosynthesis castalysed by the mitochondrial fraction of rat liver or by the microsomal fraction of cat intestinal mucosa is greatly stimulated by the supernatant fraction (6,000,000 ×g× min). This stimulation is due to the presence of several factors and evidence is presented that one of these factor is a phosphatidate phosphohydrolase. The catalytic activities of the phosphatidate phosphohydrolases present in the mitochondrial and supernatant fractions were studied using as subxtrates either an aqueous dispersion of phosphatidate or membrane‐bound phosphatidate formed as an intermediate in the biosynthesis of glycerides.

The mitochondrial phosphatidate phosphohydrolase has a high activity with aqueous phosphatidate dispersions and a low activity with membrane‐bound phosphatidate present as internal or added substrate. In contrast, the phosphatidate phosphohydrolase of the supernatant fraction has a low activity with aqueous phosphatidate dispersions and a high activity with membrane‐bound phosphatidate.

As Mg++ and F− ions are usually included in the assay systems employed for measuring glyceride biosynthesis, the effect of these ions on the particulate and soluble phosphatidate phosphohydrolases was studied to exclude the possibility that the stimulation of glyceride biosynthesis by the phosphohydrolase of the supernatant fraction was due to an artefact. It is suggested that the phosphatidate phosphohydrolase isolated in the supernatant fraction is the major phosphohydrolase activity involved in glyceride biosynthesis.
Studies on Succinate Dehydrogenase
Authors: Hauber J. , Singer T. P.
Published: March 2005

The cytoplasm of yeast contains several enzymes for the reduction of fumarate to succinate. One of these is excluded on Sephadex G‐200 and in this respect as in all of its known properties, resembles mitochondrial succinate dehydrogenase in the soluble form. Another type is distinguished by the apparent inability to oxidize succinate with any of the conventional electron acceptors. This enzyme has been subdivided into two types (I and II) which may be readily separated by chromatography on hydroxylapatite. Type I and II fumarate reductases differ from mitochondrial succinate dehydrogenase in containing acid‐extractable (rather than covalently bound) FAD, in their intracellular location, in being more stable and more resistant to inhibition by mercurials. The fumarate reductases also differ from the dehydrogenase in molecular weight, in lack of activation by substrate, and in having lower affinities for succinate and malonate and a higher one for fumarate. Conditions which are optimal for the development of mitochondrial succinate dehydrogenase (high O2 tension, low glucose concentration) repress the development of type I and II fumarate reductases and vice versa.“Petite” mutants, which lack succinate dehydrogenase, have a normal content of these fumarate reductases. Type I and II fumarate reductases, while similar in most respects, differ in molecular weight, kinetic constants and reactivity with electron donors.
Isotope Exchange Studies of the Reaction Catalyzed by ATP: Creatine Phosphotransferase
Authors: Morrison J. F. , White A.
Published: March 2005

The technique of isotope exchange at equilibrium has been used to determine if the nature of the metal‐nucleotide substrate influences the mechanism of the creatine kinase reaction.

Studies of the creatine‐phosphocreatine and ADP‐ATP exchanges in the presence of Mg2+, Ca2+ and Mn2+ showed that the initial rates varied with the total metal ion concentration, that approximately equal rates were obtained for the two exchanges under a particular set of conditions for each metal ion and that these rates were affected to only a small extent by the identity of the metal ion.

The creatine‐phosphocreatine and nucleoside diphosphate‐nucleoside triphosphate exchange rates with the cytidine, guanosine and uridine nucleotides in the presence of Mg2+ were of a similar magnitude although very much less than those obtained with the adenine nucleotides. The two exchange rates could be considered as being approximately equal only with the cytidine nucleotides us substrates.

The results have been interpreted as indicating that the creatine kinase reaction has a rapid equilibrium, random mechanism, irrespective of the nature of the activating metal ion, when adenine nucleotides are used as substrates and also in the presence of the magnesium complexes of the cytidine nucleotides. No definitive conclusions could be reached about the mechanism from the results obtained with the guanosine and uridine nucleotides.

The apparent equilibrium constant of the reaction has been shown to be dependent on the total concentration of metal ions. True equilibrium constants for the reaction in the presence of Mg2+ and Ca2+ have been determined.
Konstitution von Fusigen und dessen Abbau zu Δ2‐Anhydromevalonsäurelacton
Authors: Diekmann H. , Zähner H.
Published: March 2005

Alkaline degradation of fusigen, a sideramine from fungi, yields the known monohydroxamic acid fusarinine. l‐Ornithine and cis‐5‐hydroxy‐3‐methylpentenoic‐2‐acid occur in fusigen in equal amounts, and ornithine is the only amino acid. Amino group(s) with pK 7,1, but no free carboxyl group can be found in fusigen. The calculated equivalent weight is 280, which again points to fusarinine as a structural subunit.

By acetylation of fusigen three products are obtained, which can be separated by electrophoresis or chromatography. The titration data of the partially acetylated fusigen and the molecular weight estimation by vapour pressure osmometry of the desferriform of the fully acetylated fusigen show that fusigen is a trimeric fusarinine.

These data together with those obtained from IR‐ and NMR‐absorption spectra lead to the proposed structure: three fusarinine molecules are esterified head‐to‐tail to build a 36‐membered ring.

The quantitative estimation of all hydroxamic acids in the culture fluid of Fusarium cubense from the 2nd to the 9th day of fermentation and structural studies on some of these compounds revealed the spontaneous degradation of fusigen by ring opening and sequential split‐off of fusarinine units. An analogous degradation pathway starts from N‐acetyl‐fusigen.

The Δ2‐anhydromevalonic lactone, found in the cultures of several fungi, seems to stem from the degradation of fusarinine. The total yield of Δ2‐anhydromevalonic lactone can be increased severalfold by treatment of the culture fluid with hydrochloric acid prior to extraction.
Evidence for a Faster Degradation of an Atypical Hydroxyproline and Hydroxylysine Deficient Collagen Formed under the Effect of 2,2′‐Dipyridyl
Authors: Hurych J. , Cchvapil M. , Tichý M. , Beniač F.
Published: March 2005

Chick embryo skin slices were incubated with [14C]proline without and in the presence of 1 mM 2,2′‐dipyridyl. Collagen was isolated and digested with collagenase. The kinetics of the splitting off of small radioactive fragments showed a more rapid degradation of the undenatured hydroxyproline and hydroxylysine deficient collagen which had been formed in the presence of 2,2′‐dipyridyl, compared to the control sample. No differences in the rate of digestion have been found between heat denatured control and atypical collagen.

In parallel experiments the rate of collagenase degradation of proline rich Ascaris cuticle collagen was several times greater than that of calf skin collagen.

Skin slices incubated simultaneously with [14C]glutamic acid and 0.5 mM dipridyl showed more radioactive proline than did control samples. This is further evidence for increased degradation of atypical collagen because under these experimental conditions the metabolism of non‐collagenous protein was the same in control and dipyridyl treated samples. It is apparent that hydroxyproline and hydroxylysine decicient collagen is more susceptible to the action of collagenase and other tissue proeases.
Studies of the Energy‐Transfer System of Submitochondrial Particles
Authors: Lee Chuan‐pu , Ernster L.
Published: March 2005

The relationship between oxidative phosphorylation and the energy‐linked nicotinamide‐adenine dinucleotide transhydrogenase reaction catalyzed by phosphorylating submitochondrial particles from beef heart has been investigated. The efficiency of the particles in exhibiting oxidative phosphorylation (P/O ratio) and NADH‐linked NADP+ reduction (NADP+/O ratio) was measured, using succinate as oxidizable substrate and rotenone as inhibitor of NADH oxidase, under conditions where the phosphorylating and transhydrogenating systems were operating one by one or in parallel. When succinate oxidation was limited by increasing concentrations of malonate, the P/O ratio remained unchanged in the absence of an active phosphorylating system, and decreased in its presence. The NADP+/O ratio increased with increasing concentrations of malonate, both in the absence and presence of an active phosphorylating system. The (P + NADP+)/O ratio in the combined system approached 2, i.e., the generally accepted maximal ∼/O ratio for succinate oxidase. Active transhydrogenation caused an increase in the apparent Km for Pi in the phosphorylating system from 1.7 to 4.5 mM, and active phosphorylation caused an increase in the apparent Km for NADH in the transhydrogenating system from 21 to 40 μM. It is concluded that oxidative phosphorylation and the energy‐linked transhydrogenase reaction are competing for a common nonphosphorylated high‐energy intermediate generated by the respiratory chain. The kinetic evidence presented further suggests that the two systems interact with two different moieties of this high‐energy intermediate.
Investigations on the Reaction of Metals with Collagen in vivo
Authors: Adam M. , Kühn K.
Published: March 2005

After dosing rats with gold thiosulphate a hardening of the collagen can be observed that is attributed to cross‐linkage of the fibrils by the gold ion. Initially no reaction takes place between gold thiosulphate and collagen in vitro. Only after the central gold ion is set free by oxidative destruction of the thiosulphate groups can it enter into a coordination complex with the side‐chain groups, forming new intermolecular bonds. In vivo the gold complex is apparently first taken up into the fibril by virtue of electrostatic forces. In a second slower reaction the thiosulphate groups are displaced by the side chain groups resulting in the cross‐linkage.
Investigations on the Reaction of Metals with Collagen in vivo
Authors: Adam M. , Fietzek P. , Deyl Z. , Rosmus J. , Kühn K.
Published: March 2005

Mercury, copper and bismuth compounds react in vivo with insoluble collagen in a way similar to gold thiosulphate. The introduction of artificial cross‐links increases the overall stability of the collagen and lowers its solubility. As a result the fibrils acquire a more finely detailed cross‐striation pattern as seen under the electron microscope.
Associations de poly A et poly U en milieu acide
Authors: Massoulié J.
Published: March 2005

In this paper the thermal stability of poly (A + U) and poly (A + 2U) in acid solution is studied. It is known that at low pH poly A associates with itself to form a double protonated helical structure, poly (A + A). The dissociation Tm's of poly (A + U) and poly (A + 2U) do not vary with pH as long as they are higher than TmA [the dissociation temperature of poly (A + A)]. TmA itself varies with the pH (it increases as the pH is lowered) and thus, there are pH values at which TmA equals the dissociation Tm's of the complexes poly (A + U) and poly (A + 2U). Below such pH's, Tm2–3, Tm3–1, Tm2–1 decrease as the pH becomes more acid. In contrast, Tm3–2 does not exhibit such a variation. The transition corresponding to this last Tm [the partial dissociation of poly (A + 2U) into poly (A + U)] does not change the concentration of “free” poly A.

We conclude that the change in thermal stability of the complexes in this region of pH is due only to their competition with poly (A + A) and that poly (A + U) and poly (A + 2U) are not modified.

At low ionic strength, the transitions observed change with the pH and, by identifying them by means of two independent methods (continuous variation method, and comparison of spectral variations) we have shown that the stability diagram (temperature versus pH) formally resembles the stability diagram (temperature versus ionic strength) at neutral pH (Fig.3), when pH is decreased and/or ionic strength is increased, poly (A + 2U) is relatively more stable than poly (A + U): The formation of poly (A + A) lowers the stability of both poly (A + U) and poly (A + 2U), but, since the proportion of adenylic residues is 1/3 in this last complex, against 1/2 in the former, poly (A + 2U) is less destabilized, and is more sensitive to the diminution of electrostatic repulsion brought about by the sodium ion concentration. These effects are summarized in a three‐dimensional diagram temperature‐pH‐ionic strength (Fig.9).

Some of the transitions occuring in acidic solution appear to be irreversible, or very slowly reversible. Such is the case of the formation of poly (A + U). We have shown that this effect is due to the structure poly (A + A). When the dissociation temperature (TmA) of this structure is higher than that of poly (A + U), it is necessary to form two A – U pairs replacing one A – A pair in order to obtain the free energy decrease. Therefore, such a reaction cannot occur in two steps, and this suggests a third order mechanism. Another example is given by the rearrangement of poly (A + U) into poly (A + 2U) and poly (A + A). This observation leads us to a general rule concerning the possibility of reorganization in a system of polynucleotides where several associations are possible [for instance it answers the question as to why poly G cannot expel poly I from poly (I + C)].
The Stereochemistry of α‐Oxidation of Fatty Acids in Plants
Authors: Hitchcock C. , Morris L. J. , James A. T.
Published: March 2005

When [1‐14C] palmitic acid was incubated with young pea leaves or solutions of their acetonedried powders, 2‐hydroxy [1‐14C]palmitic acid accumulated. This metabolite has been isolated as its methyl ester. When diluted with unlabelled synthetic methyl D‐2‐hydroxypalmitate to known specific activity, and recrystallised, the crystals and mother liquor residues retained the same specific activity. When diluted with unlabelled synthetic methyl L‐2‐hydroxypalmitate to known specific activity and recrystllised, the crystals were almost non‐radioactive. The radoactive metabolite therefore has the D‐configuration.

Unlabelled 2‐hydroxypalmitic acid isolated from pea leaves was shown to have the D‐configuration by direct measurement.
The Regulation of Isoleucine‐Valine Biosynthesis in Saccharomyces cerevisiae
Authors: Magee P. T. , de Robichon‐Szulmajster H.
Published: March 2005

Acetohydroxyacid synthetase activity has been characterized, independently of the acetoin‐forming system in Saccharomyces cerevisiae by a differential colorimetric assay. Maximum pH and Km values have been established for both enzymes with pyruvate as the substrate. Acetolactate formation by acetohydroxyacid synthetase has been shown directly by the separation of dinitrophenylosazones by thin‐layer chromatography. Evidence for the biosynthetic role of the activity measured resides in its presence in wild‐type strains, in its absence in the is2 class of mutants (isoleucine‐valine auxotrophs) and in its reappearance in prototrophic revertants of these mutants.
Komplexbildung von Nucleinbasen mit Cu2+
Authors: Sigel H.
Published: March 2005

By means of UV difference spectra, the acidity constants KHHL of the N‐1‐proton in the nucleotides inonine, guanosine, uridine, and thymidine 5′‐triphosphate were measured. The same deprotonation (KHCuHL) in the respective Cu2+ complexes was also determined. The measurement were carried out with and without (Table 1) addition of NaClO4 (0.1 M). It was found that the influence of the ionic strength is great, possibly due to the formation due to Na+ complexes.

The difference, ΔpKA=pKHHL–pKHCuHL∽ 2.0, for the nucleotide systems is of the same order as the respective value 2.2 of the Cu2+ guanosine system. This indicates a strong interaction between Cu2+ and the nucleic base in the Cu2+‐nucleotide complexes. From experimental indices and the analogy to the Cu2+‐ATP complex, it is concluded that macrochelates are formed.

The acidity constants determined by means of UV difference spectra were confirmed by potentiometric titrations (Table 2).

The Cu2+‐nucleoside triphosphates are known to form stable complexes with 2,2′‐bipyridyl. In such ternary complexes, the nucleic base can no longer coordinate to the Cu2+. The relatively small ΔpKBipy/A values (Table 2) are in agreement with this.

The hydrolytic tendencies of Cu2+ bound to the different nucleotides were also estimated (Table 2). The pKHCuL(H2O)x values show that the hydrolytic tendency of the Cu2+ complexes decreases in the order CTP > ATP > TTP > UTP > ITP ∽ GTP. The influence of the coordination number of the different ligands and also other problems concerning nucleotide complexes were discussed.
Acides ribonucléiques messagers de la glande thyroïde
Authors: CARTOUZOU G. , ATTALI J.‐C. , LISSITZKY S.
Published: March 2005

Nuclear and cytoplasmic RNA from sheep thyroid slices in vitro labeled with [3H]uridine or [32P]phosphate from 5 min up to 9 h, have been obtained by different phenol extraction procedures. Early‐labeled RNA was only extracted by phenol containing 0.1 or 1% (w/v) sodium dodecylsulfate (SDS) at 0° or 60°, whereas stable nuclear or polysomal RNA was easily extracted by pherol at 0°.

Time course of incorporation of label into subcellular particles has shown the early labeling of nuclear RNA and the transfer of radioactivity into the cytoplasm.

Rapidly‐labeled RNA extracted from nuclei by phenol‐1% (w/v) SDS and analyzed by sedimentation was shown to sediment in three discrete classes 50–30S, 22 S and 13 S, different from ribosomal RNA. After 9 h of incubation the 22 S and 13 S labeled RNAs were still present in detectable amounts in the nuclei, indicating a somewhat low turnover rate for these components.

The kinetics of incorporation of label into polysomes was studied in thyroid slices incubated from 15 min up to 5 h with [3H]uridine or [32P]phosphate. RNA was dissociated from polysomes by dodecylsulfate treatment and centrifuged on sucrose gradient. As for nuclei, the rapidlylabeled RNAs sediment in discrete size classes, 22 S and 13 S. After a long incubation time (5 h) the label was predominant in 28 S and 18 S ribosomal RNA but 28 S RNA was not completely labeled. Up to 30 min labeling a high molecular weight, early‐labeled RNA was present in purified polysomes. Its radioactivity declines after 60 min labeling.

A part of the rapidly labeled polysomal RNA can be reversibly separated from rRNP by the action of EDTA (1.25 to 5 μ moles EDTA/mg RNP). It sediments in a broad zone (12–30 S) of high specific radioactivity. Increasing Mg++ concentration results in the reassociation of rapidly‐labeled RNA to ribosomal sub‐particles.

Buoyant densities of the polysomal RNP particles obtained by EDTA treatment of 32P‐labeled polysomes and stabilized by means of formaldehyde fixation, were determined by banding in CsCI gradients. The bulk of the stable material banded at characteristic densities (d= 1.55 and 1.48), but most of the rapidly‐labeled RNA banded at d= 1.38.

The specific radioactivity of this material was the same as that of the 12–30 S RNA isolated by sucrose gradient centrifugation from the same EDTA‐treated polysomes. Preliminary double labeling experiments and computation of the RNA to protein ratio calculated from the RNA and protein density values indicate this material to be early‐labeled nucleoprotein particles with a high protein content.
Modification of the in vitro Amino Acid Incorporation Capacity of Rat Liver after in vivo and in vitro Treatments
Authors: von der DECKEN A.
Published: March 2005

Rats were maintained for several days on a protein‐free carbohydrate containing diet which was changed to a protein‐rich diet approximately 14–17 h before decapitation. The ability to incorporate amino acids into protein was enhanced after the nutritional alteration, and this enhancement was unaffected by pretreatment in vivo with the antibiotics actinomycin d and chloramphenicol. Molecular sieving of microsomes and cell sap through Sephadex G‐25 removed components or factors from the fractions. Under these conditions and in the presence of optimal amounts of cell sap, GTP and an amino acid mixture stimulated the incorporating activity of the preparations in a manner such that the originally observed differences between the two types of rats became less. These results were interpreted to suggest that the in vivo predetermined capacity of protein synthesis could be altered. These alterations implied an increase rather than a decrease of the originally in vitro observed amino acid incorporating activities.
Synthesis of Lens Protein in vitro
Authors: BLOEMENDAL H. , ZWEERS A. , SCHOENMAKERS J. G. G.
Published: March 2005

Poly U‐directed stimulation of preincubated calf lens ribosomes revealed that these particles from a mammalian source have a phenylalanine incorporation ability comparable to the Escherichia coli system. A search was made for optimal conditions.

After variation of the magnesium concentration during preincubation two levels of maximal incorporation were observed. The region of highest relative stimulation did not coincide with these maxima. Preincubation under conditions of optimal amino acid incorporation yields 80S monomers and to a lesser extent 120S particles. No smaller units or breakdown products were observed in the analytical ultracentrifuge. Such particles could be demonstrated after prolonged dialysis of either polysomes or 80S monomers against 0.1 mM MgCI2. Their sedimentation coefficients were 50 S and 30 S respectively but not 60 and 40 S.
The Energy Metabolism of Clostridium kluyveri
Authors: THAUER R. K. , JUNGERMANN K. , HENNINGER H. , WENNING J. , DECKER K.
Published: March 2005

The energy metabolism of Clostridium kluyveri has been reinvestigated. The organism was grown on ethanol, acetate and bicarbonate or, on crotonate and bicarbonate as the sole carbon sources. The net ATP gain (G) — moles of ATP produced per mole of substrate fermented or product formed — was determined. The G‐values obtained show that ATP needed for growth is produced exclusively by a substrate‐level phosphorylation using acetyl CoA as the “energyrich” intermediate and not by phosphorylation coupled to an electron‐transport process, as has been widely assumed.
Etude de la méthionyl tRNA synthétase de Escherichia coli
Authors: CASSIO D.
Published: March 2005

Treatment of partially purified methionyl tRNA synthetase from Escherichia coli B (E. coli B) with p‐hydroxymercuribenzoate (pHMB) leads to loss of the capacity to form methionly adenylate and methionyl tRNA. Inactivation of the capacity to activate methionine could not be reversed by the addition of GSH or 2‐mercaptoethanol.

The Presence of low concentrations of l‐methioninyl adenylate (a structural analog of methionyl adenylate) during pHMB‐treatment, results in complete and selective protection of the active site responsible for the activation of methionine. Under these conditions, the addition of 2‐mercaptoethanol leads to full recovery of the capacity to charge tRNA.

The enzyme which has lost the capacity to form methionyl tRNA as a result of pHMB‐treatment in the presence of methioninyl adenylate, has the same elution characteristics as untreated enzyme when examined by gel filtration through Sephadex G‐200. It is concluded that loss of the capacity to charge tRNA is not a consequence of dissociation of the enzyme into subunits.

These results provide a clear‐cut distinction between the active site responsible for the activation of the amino acid, and the site(s) involved in the formation of aminoacyl tRNA, in the case of methionyl tRNA synthetase.
Quantitative Evaluation of O‐Glycosidic Linkages between Sugars and Aminoacids in Ovine Submaxillary Gland Mucoprotein
Authors: HARBON S. , HERMAN G. , CLAUSER H.
Published: March 2005

The O‐glycosidic nature of almost 85% of the linkages between the prosthetic disaccharides and ‐OH groups of serine and threonine residues has been definitively established in ovine submaxillary gland mucoprotein (OSM). The alkali‐lability of the sugar protein linkages was attributed to a β‐elimination mechanism of the disaccharides and the stoichiometric conversion of serine to dydroalanine and of threonine to α‐amino crotonic acid has been demonstrated in alkali‐treated OSM. Serine and threonine residues are involved within these O‐glycosidic linkages in equimolecular proportions. Preliminary results concerning the structure of the peptide chain in the vicinity of the prosthetic group linkages are reported.
Studies on Succinate Dehydrogenase
Authors: TISDALE H. , HAUBER J. , PRAGER G. , TURINI P. , SINGER T. P.
Published: March 2005

Autolysates of brewer's yeast contain several isoenzymes of fumarate reductase. One group (Type I) has a molecular weight of 62,000 to 63,000, as determined by chromatography on Sephadex, and 5 components in the group have been detected and partially or completely separated on triethylaminoethyl cellulose. Another group (Type II) consists of at least 2 isoenzymes. The predominant component shows a molecular weight of 34,000 and the minor one 112,000 ± 10,000 on Sephadex. One of the Type I enzymes has been extensively purified until it shows a single component on gradient centrifugation, although it appears to be heterogeneous on polyacrylamide electrophoresis. The prosthetic group is FAD and, in addition, iron and possibly, copper appear to be present. In contrast to mitochondrial succinate dehydrogenase the FAD is not covalently bound and the non heme iron is not linked to labile sulfide. Preliminary electron paramagnetic resonance data suggest that the iron may undergo oxidation‐reduction during the catalytic cycle. The absorption spectrum manifests the 450 mμ band of flavoproteins but there is an anomalous absorption below 400 mμ and in the long wave‐length region. Dithionite and succinate bleach the 450 mμ band and fumarate partially restores the color of the enzyme.
Structural and Metabolic Heterogeneity of Rat Liver Glycerophosphatides
Authors: ARVIDSON G. A. E.
Published: March 2005

A quantitative thin‐layer chromatographic method is described for the separation and isolation of subfractions with different degrees of unsaturation of phosphatidylcholines and phosphatidylethanolamines from rat liver. In fasting male and female rats the tetraunsaturated or arachidonoyl‐containing subfraction was found to be of quantitative dominance in both phosphatidylcholines and phosphatidylethanolamines, whereas the latter contained relatively more of the hexaunsaturated fraction than the phosphatidylcholines. All the monoenoic subfractions contained more palmitic acid than stearic acid. In both the phosphatidylcholines and the phosphatidylethanolamines more than 50% of the stearic acid in each phospholipid was recovered in the tetraenoic fraction in both male and female rats. Incorporation of 32P and [1,2‐14C2]ethanolamine was found to occur at a high rate in the hexaenoic phosphatidylethanolamines. Another characteristic finding was the comparatively low metabolic reactivity of the arachidonoyl fraction in both phosphatidylcholines and phosphatidylethanolamines.

The results have tentatively been interpreted to reflect differences in substrate specificity of CDPcholine: 1,2‐diglyceride cholinephosphotransferase and CDPethanolamine: 1,2‐diglyceride ethanolaminephosphotransferase towards different molecular species of l‐1,2‐diacylglycerol. The differences observed between the hexa‐and tetraunsaturated subfractions may also be related to differences in the turnover rate between polyunsaturated fatty acids of the linoleic acid type and those belonging to the linolenic acid series.
Proton Translocation Coupled to ATP Hydrolysis in Rat Liver Mitochondria
Authors: MITCHELL P. , MOYLE J.
Published: March 2005

Glass electrode measurements of the pH of anaerobic suspensions of rat liver mitochondria during the hydrolysis of ATP to ADP and Pi by the oligomycin‐sensitive ATPase show that almost 2H+ ions are translocated outwards through the M phase of the cristae membrane per ATP molecule hydrolysed. Adenylate kinase activity is minimised by the presence of EDTA, and valinomycin must be added to the normal mitochondrial suspensions to collapse the membrane potential and permit the outwardly translocated H+ ions to diffuse practically quantitatively to the glass electrode system.

Classical inhibitor studies of the overall ATPase reaction catalysed by the mitochondria indicate that the specific ATP/ADP porter is not rate‐limiting under the conditions of these experiments; and it is also shown that the overall process of ATP entry and ADP + Pi exit through the porter systems in the M phase is not coupled to net proton translocation. It is concluded that the ATPase system responsible for or coupled to proton translocation has a proton translocation quotient (→H+/P) of 2, corresponding to that of the type II ATPase of the chemiosmotic hypothesis.
Light Chain Types in Pig Antibodies to the 2,4‐Dinitrophenyl Group
Authors: Yamashita T. , Franěk F. , Škvařil F. , Šimek L.
Published: March 2005

Sera of individual pigs immunized by dinitrophenylated bovine immunoglobulin served as the source of antibodies to the 2,4‐dinitrophenyl group and of γG‐immunoglobulin isolated after absorption of antibody (nonspecific γG‐immunoglobulin). The S‐sulfo‐derivatives of light chains of antibody and of nonspecific immunoglobulin were separated by ion‐exchange chromatography on SE‐Sephadex into the individual types (λ‐, π‐ and ϱ‐chains). Fingerprinting as well as immunoprecipitation failed to reveal any differences between the corresponding types of light chains of antibodies and of nonspecific immunoglobulin. In comparison with nonspecific immunoglobulin of normal animals the ratio of the individual types was shifted in favour of the π‐ and ϱ‐chains both with antibodies and with nonspecific immunoglobulin of immunized animals. As shown by peptide map analysis, the ϱ‐chains are in certain respects related to the heavy chains. They contain hexosamines and their amino acid composition is different from that of the γ‐ and ϱ‐chains. The data on weight ratio of heavy to light chains in the antibodies support the conclusion that the major component of the ϱ‐chains is not represented by heavy chain fragment but by a separate type of light chains.