bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitochondrial DNA variation in the Italian Heavy Draught Horse
Authors: Lancioni Hovirag , Cardinali Irene , Giontella Andrea , Antognoni Maria Teresa , Miglio Arianna
Published: May 2020

Background

In the last decades, Italy as well as other developed countries have registered a decrease in the population size of many local horse breeds. The continuous crossbreeding has determined the dilution of genetic heritage of several native breeds. The Italian Heavy Draught Horse (IHD) is the only autochthonous Italian coldblooded horse among these breeds; therefore, it represents a resource to be preserved. In 1927, the first generation of this breed was officially created by crossing different Heavy Draught horses with local mares and recorded in a Studbook.

Methodology

To provide the first comprehensive overview of the genetic diversity of Italian Heavy Draught horses from Central Italy, we produced and phylogenetically analysed 52 mitochondrial DNA (mtDNA) control-region sequences. Furthermore, we evaluated data available from GenBank (N = 568) to have a more complete scenario and to understand the relationships with other European Heavy Draught horse breeds.

Results

Among the IHD samples that were analysed, we identified ten of the 17 haplogroups described in modern horses. Most of these sequences fell into L, G, and M lineages, thus showing the overall mtDNA legacy of the ancestral mares that were probably used at the initial stages of breeding selections a long time ago. The high mitochondrial haplotype diversity (Hd = 0.969) found in our samples reflected the multiple maternal origins of the horses. Our results highlighted a considerable percentage of haplotypes shared especially with Bardigiano and Hungarian Heavy Draught breeds. Furthermore, both the presence of four unique haplotypes detected in our samples and their absence among all equine mitochondrial published data demonstrate a mitochondrial peculiarity that needs to be further investigated and preserved with careful breeding practices.
Application of High Resolution Melt analysis (HRM) for screening haplotype variation in a non-model plant genus: Cyclopia (Honeybush)
Authors: Galuszynski Nicholas C. , Potts Alastair J.
Published: May 2020

Aim

This study has three broad aims: to (a) develop genus-specific primers for High Resolution Melt analysis (HRM) of members of Cyclopia Vent., (b) test the haplotype discrimination of HRM compared to Sanger sequencing, and (c) provide an example of using HRM to detect novel haplotype variation in wildC. subternataVogel. populations.

Location

The Cape Floristic Region (CFR), located along the southern Cape of South Africa.

Methods

Polymorphic loci were detected through a screening process of sequencing 12 non-coding chloroplast DNA segments across 14 Cyclopia species. Twelve genus-specific primer combinations were designed around variable cpDNA loci, four of which failed to amplify under PCR; the eight remaining were applied to test the specificity, sensitivity and accuracy of HRM. The three top performing HRM Primer combinations were then applied to detect novel haplotypes in wildC. subternatapopulations, and phylogeographic patterns ofC. subternatawere explored.

Results

We present a framework for applying HRM to non-model systems. HRM accuracy varied across the PCR products screened using the genus-specific primers developed, ranging between 56 and 100%. The nucleotide variation failing to produce distinct melt curves is discussed. The top three performing regions, having 100% specificity (i.e. different haplotypes were never grouped into the same cluster, no false negatives), were able to detect novel haplotypes in wildC. subternatapopulations with high accuracy (96%). Sensitivity below 100% (i.e. a single haplotype being clustered into multiple unique groups during HRM curve analysis, false positives) was resolved through sequence confirmation of each cluster resulting in a final accuracy of 100%. Phylogeographic analyses revealed that wildC. subternatapopulations tend to exhibit phylogeographic structuring across mountain ranges (accounting for 73.8% of genetic variation base on an AMOVA), and genetic differentiation between populations increases with distance (p < 0.05 for IBD analyses).

Conclusions

After screening for regions with high HRM clustering specificity—akin to the screening process associated with most PCR based markers—the technology was found to be a high throughput tool for detecting genetic variation in non-model plants.
Obtention et etude de doubles mutants chlorate‐resistants chez Escherichia coli K12
Authors: Marcot J. , Azoulay E.
Published: July 2002

Three double mutants were prepared from single mutant chl‐r strains of Escherichia coli K12 lacking nitrate reductase activity. When extracts of these three double mutants were mixed, nitrate reductase activity was reconstituted.
La localisation microsomale de la synthese des acides gras dans le foie de la souris vivante
Authors: Favarger P. , Gerlach J.
Published: July 2002

Mice were given glucose‐U‐14C and the radioactivity of triglyceride and phospholipid glycerol and fatty acids was measured 30 sec, 3 or 30 min after the i.v. administration in liver microsomes and supernatant. After the acetate administration the radioactivity of palmitic and stearic acids and that of their carboxyl carbons was also measured. The repartition of the radioactivity was discussed in relation with the localization of fatty acid synthesis. In agreement with our previous results it was suggested that the endoplasmic reticulum is the main site of this synthesis.
Mise en evidence chez les vegetaux superieurs d'une association enzymatique bifonctionnelle intervenant dans la biosynthese de l'acide shikimique
Authors: Boudet A.
Published: July 2002

In the extracts of Quercus pedunculata roots, the activities of 5‐dehydroquinate hydro‐lyase and shikimate: NADP oxydoreductase are eluted in the same fractions whatever separation procedures are used: chromatography on Sephadex G 100, DEAE cellulose and hydroxylapatite, centrifugation in sucrose density gradient, disc electrophoresis. These results are closely related to those obtained on the aggregate of enzymes involved in the shikimate pathway in Neurospora crassa. The molecular weight of the association determined by gel filtration is about 55,000.
Etude in vitro de la synthese de la progesterone dans le corps jaune cyclique humain: Role de la prostaglandine F2α
Authors: Santos Agostinho Almeida , Hermier Claude , Netter Albert
Published: July 2002

When HCG and PG F2α are added into the medium at their “maximal effective dose” the effect is supra‐maximal. In our experimental procedure, acetylsalicylic acid does not inhibit the synthesis of progesterone stimulated by LH. According to these results it seems that PG F2α is not the necessary membrane mediator between the hormonal‐receptor and the adenylcyclase system.
The structure of the cell wall of Staphylococcus aureus studied with neutron scattering and magnetic birefringence
Authors: Torbet J. , Norton M.Y.
Published: July 2002

The cell wall complex was extracted from Staphylococcus aureus and characterized in suspension by means of small‐angle neutron scattering and magnetically induced birefringence. The neutron scattering measurements show that the complex has a thickness of ∼420 Å, a mass per unit area of 93 ± 11 daltons/Å2 and is ∼75% water by volume. The neutron scattering density is higher near the surface than in the interior in accordance with a trilamellar structure. The magnetically induced birefringence measurements demonstrate that a high degree of magnetic orientation is possible due to the anisotropic nature of the wall complex structure.
Does the sarcoplasmic reticulum achieve chemiosmotic equilibrium in relaxed muscle?
Authors: Jeacocke Robin
Published: July 2002

Measurements of 45Ca2+ efflux from bovine skeletal muscle fibres preloaded with this isotope indicate that the sarcoplasmic free Ca2+ concentration rises and falls under anaerobic (or uncoupled) and aerobic conditions, respectively. Dantrolene has only a small effect on these responses which are larger in predominantly slow‐twitch fibre preparations. Dantrolene slightly reduces the resting free Ca2+; this is much more pronounced in rectus abdominis (mainly fast‐twitch) than in sternomandibularis (mainly slow‐twitch). It is proposed that the sarcoplasmic reticulum in the resting muscle fibre achieves a state close to chemiosmotic equilibrium and that aerobic metabolism generates a higher phosphorylation potential, permitting a larger Ca2+ electrochemical potential difference to develop across the sarcoplasmic reticulum membrane under aerobic conditions.
Inhibition by N‐ethylmaleimide of the MgATP‐driven proton pump of the chromaffin granules
Authors: Flatmark Torgeir , Grønberg Martin , Husebye Eystein , Vik Berge Sissel
Published: July 2002

The thiol reagent N‐ethylmaleimide (NEM) completely inhibits the proton pump activity of the H+‐ATPase in chromaffin granule ‘ghosts’ at concentrations which only partly (∼20%) inhibit the Mg2+‐dependent ATP hydrolysis. Half‐maximal inhibition was obtained at ∼13 μM NEM as compared to 18 μM for the classical proton channel inhibitor N,N'‐dicyclohexylcarbodiimide (DCCD), and the apparent stoichiometry of the inhibitors at complete inhibition was NEM:DCCD ⋍ 1 : 2. High concentrations of NEM (⪢100 μM) induce a dissipation of the transmembrane potential generated by MgATP. These findings establish NEM as a valuable proton channel inhibitor in chromaffin granules and explain the rather complex effect of NEM previously reported for catecholamine accumulation in this organelle.
Spin equilibrium relaxation kinetics of cytochrome P450 LM2
Authors: Ziegler M. , Blanck J. , Ruckpaul K.
Published: July 2002

The relaxation kinetics of the temperature‐dependent spin equilibrium of cytochrome P450 LM2 has been resolved by means of a laser temperature‐jump device. The Nd laser system in the Q‐switched mode delivers 3 J/25 ns pulses which were Raman shifted to 1.89 μm by use of a high pressure H2‐gas cell. The LM2 equilibrium relaxation proceeds in the ns‐range, the rate constants of the on‐ and off‐reactions amount to about 106 s−1 in correspondence with respective processes of other hemoproteins and protein‐free model compounds. Benzphetamine increases the on‐rate constant (low‐spin → high‐spin) about 5 fold, the off‐process is nearly unchanged.
Effect of CO2 on the energization of thylakoids in leaves of higher plants
Authors: Garab Gy. , Burgos A.A.Sanchez , Zimányi L. , Faludi-Dániel Á.
Published: July 2002

We investigated the effect of CO2 on the flash‐induced electrochromic absorbance change of chloroplasts in leaves of higher plants. In leaves depleted of CO2 the initial electrochromic rise was followed by a fast (t
10–20 ms) and a slow (100–200 ms) decay. These kinetic components could be correlated with a dissipative and an ATP‐synthetizing current, respectively. In leaves supplied with CO2 an additional slow electrochromic rise (5–10 ms) appeared in the absorbance change. This component could be tentatively correlated with the enhancement of the electron transport by CO2 between the two photosystems. In leaves supplied with CO2 the decay could be fitted with a single exponential with a t
≈200 ms. We conclude that both energization and ATP‐synthesis are strongly regulated by CO2 in chloroplasts in situ.
Streptozotocin diabetes results in increased responsiveness of adipocyte lipolysis to glucagon
Authors: Chatzipanteli Katina , Saggerson David
Published: July 2002

Adipocytes from streptozotocin‐diabetic rats are ∼50‐times more sensitive to the lipolytic action of glucagon. This change is only perceived in the presence of a small quantity of adenosine deaminase which itself has little effect on basal lipolysis. Insulin treatment restores glucagon sensitivity to normal.
Structure determination of the major asparagine‐linked sugar chain of human factor VII—von Willebrand factor
Authors: Debeire P. , Montreuil J. , Samor B. , Mazurier C. , Goudemand M. , Van Halbeek H. , Vliegenthart J.F.G.
Published: July 2002

N‐glycosidically‐linked glycans released by hydrazinolysis of human factor VIII/von Willebrand factor (FVIII/vWf) were seperated by high‐voltage electrophoresis. Five fraction were obtained, one of them representing 60% of the total amount of the N‐glycosidically‐linked glycans of FVIII/vWf. On the basis of the carbohydrate composition, methylation analysis and 500 MHz 1H‐NMR spectroscopy, we describe the primary structure of this major glycan which is of the monosialylated and monofucosylated biantennary N‐acetyllactosaminic type.
Effect of trifluoperazine on 3H‐labeled protein secretion induced by pentoxifylline, cholinergic or adrenergic agonists in rat lacrimal gland. A possible role of calmodulin?
Authors: Mauduit Philippe , Herman Geneviève , Rossignol Bernard
Published: July 2002

In rat lacrimal gland, cholinergic, α‐ or β‐adrenergic or methylxanthine stimulations of protein secretion are extracellular calcium dependent. 10 μM trifluoperazine (TFP) inhibited only cholinergic and α‐adrenergic stimulations. Half maximal effect was observed at 30 μM, with all inducers except norepinephrine (3 μM). 10 or 30 μM TFP also suppressed the decrease of L‐[3H]leucine incorporation into protein due to carbamylcholine. 100 μM TFP inhibited protein secretion and L‐[3H]leucine incorporation. 500 μM TFP promoted cell lysis. It is suggested that: (a) at 100 μM TFP, inhibition is not specific for protein secretion; (b) at 30 μM TFP, inhibition could be related to a role of calmodulin in the secretory regulation process.
Difference between tortoise and hen lysozymes in the mode of association with N‐acetyl D‐glucosamine as revealed by proton magnetic resonance spectroscopy
Authors: Chatterjee N. , Banerjee Kalyan K. , Sen A.
Published: July 2002

Tortoise lysozyme, unlike hen lysozyme, does not distinguish between the α‐ and β‐anomeric forms of N‐acetyl D‐glucosamine. This indicates that α‐ and β‐anomeric forms of the inhibitor have the same affinities and experience identical magnetic environments in tortoise lysozyme. The dissociation constant of tortoise lysozyme—inhibitor complex was calculated from chemical shift data and found to be 3.5 × 10−2 M. The enthalpy of dissociation was calculated to be 5.0 kcal/mol.
Alteration of adenine nucleotide pool in old rat liver and its normalization with ammonium succinate
Authors: Kaminsky Yu.G. , Kosenko E.A. , Kondrashova M.N.
Published: July 2002

Ammonium succinate administration into the old rats increases the sum of adenine nucleotide and normalizes all indices of adenine nucleotide metabolism in the liver to the levels typical for the intact young animals.
A stimulating effect of guanyl nucleotides on the rat‐liver soluble cyclic GMP high‐affinity phosphodiesterase activity
Authors: Spina Annamaria , Chiosi Emilio , Paolisso Giuseppe , Laurenza Antonio , Illiano Gennaro
Published: July 2002

The high affinity (low K
m) cyclic GMP phosphodiesterase (PDE) is activated by GTP, while the cyclic AMP PDE is not. GTP and its hydrolysis‐resistant analogue, guanylylimidodiphosphate (GppNHp), display a half‐maximal stimulating effect at almost the same concentration (5 × 10−6M). The GTP stimulating effect is not observed when the socalled cyclic GMP low affinity (high K
m) PDE is operative. GTP cooperates with the increase of the substrate concentration on removing the IBMX inhibitory effect. The isolation through a classical chromatographic procedure on a DEAE‐cellulose column, of a PDE fraction specific for cyclic GMP, results in the loss of the GTP stimulating effect.
Effect of lipophilic vitamins on the erythrocyte membrane
Authors: Viti V. , Cicero R. , Callari D. , Guidoni L. , Billitteri A. , Sichel G.
Published: July 2002

Structural changes induced by the fat‐soluble vitamins A, D3, E and K1 in natural membranes were studied by 31P NMR and fluorescence anisotropy on erythrocyte ghosts; the occurrence of cell fusion following vitamin addition was detected by optical microscopy of intact cells. Vitamins A, E and K1, which produce cell fusion, also induce the formation of configurational phases other than the bilayer and increase, at a different extent for the different vitamins, membrane fluidity. Vitamin D3, on the contrary, induces aggregation without fusion, paralleled by bilayer phase stabilization and microviscosity increase. A correlation between fusion phenomena and structural variations in the bilayer organization is therefore suggested.
Synthesis of 2‐deoxyglucitol from 2‐deoxy‐D‐glucose by the fungus Puccinia graminis
Authors: Manners J.M. , Maclean D.J. , Scott K.J.
Published: July 2002

After incubation of glucose‐grown mycelium of Puccinia graminis with 2‐deoxy‐D‐[U‐14C]glucose, all cellular 14C was present in compounds soluble in 80% (v/v) ethanol. Metabolites identified included 2‐deoxyglucitol, and free and phosphorylated forms of 2‐deoxyglucose and 2‐deoxygluconate. This is the first report of 2‐deoxyglucitol as a metabolite of 2‐deoxyglucose in any organism, and in P. graminis, this confirms previous proposals that the free D‐glucose is directly reduced to D‐glucitol in vivo.
Changes in microsomal hemoprotein content and glucose 6‐phosphatase activity during low‐temperature acclimation of Tetrahymena pyriformis
Authors: Fukushima Hirofumi , Watanabe Takehito , Sasaki Noboru , Takeda Tomoo , Nozawa Yoshinori
Published: July 2002

To examine the temperture‐associated alterations in microsomal enzymes in an eukaryote, Tetrahymena cells were transferred from 39.5–15°C. The content of cytochrome b‐560ms, a cytochrome similar to but not identical with liver microsomal cytochrome b
5, was slightly increased within 2 h after temperature shift‐down, then gradually decreased, and reached the cytochrome b‐560ms level of the 15°C‐isothermally grown cells within 10 h following the temperature‐shift. Cytochrome P‐450 was not detected in Tetrahymena microsomes. The presence of a co‐binding hemoprotein with a main peak at 420 nm was, however, observed. The amount of this hemoprotein was unchanged for 2 h after cold‐shift. Later, it increased gradually and reached the maximum level at 10 h. Glucose 6‐phosphatase activity increased slightly at 10 h, when cell division had already been regained. We conclude that cytochrome b‐560ms, which is linked to the desaturase, may be essential for short‐term adaptation (2 h after shift), while the amount of co‐binding hemoprotein and the activity of glucose 6‐phosphatase would be associated with long‐term adaptation (10 h after temperature shift) in Tetrahymena cells.
A low‐Mr factor isolated from Escherichia coli inhibits eukaryotic in vitro protein synthesis
Authors: Skelly Susan M. , Clark Virginia L.
Published: July 2002

The effect of a low‐M
r factor, partially purified from E. coli B, was investigated in E. coli, reticulocyte, and wheat germ lysate in vitro protein synthesis systems. Equal concentrations of factor were needed to inhibit protein synthesis in the eukaryotic system as compared to the prokaryotic system. Experiments suggested that the factor inhibits the initiation step in the eukaryotic systems.
Partial proteolytic digestion of isolated bacterial photoreaction centers without apparent alteration of pigment‐protein interaction
Authors: Giménez-Gallego Guillermo , Suanzes Pilar , Ramírez Juan M.
Published: July 2002

Photoreaction centers were purified from wild‐type Rhodospirillum rubrum by a new procedure which reduced to undetectable levels the activities of contaminant endogenous proteinases. As shown by sodium dodecylsulfate‐polyacrylamide gel electrophoresis, mild digestion of the centers with α‐chymotrypsin degraded the 36 kDa (H) polypeptide but did not elicit significant alterations in the 29 (M) and 25 kDa (L) constituents. While short‐term incubation with trypsin removed H and decreased the M
r of M to that of L, a prolonged treatment with trypsin yielded preparations with polypeptides of 19 and 5 kDa. Since the proteolyzed preparations retained the near infrared absorption spectrum of the native photoreaction center and exhibited photochemical activity, an apparent 3–4‐fold increase of the primary donor:protein ratio was achieved.
Phosphorylation of mitochondrial membrane proteins: effect of the surface potential on monoamine oxidase
Authors: Famulski Konrad S. , Nałȩcz Maciej J. , Wojtczak Lech
Published: July 2002

Proteins of mitochondrial membranes become phosphorylated when liver mitochondria are incubated with ATP in the presence of Mg2+. This is accompanied by an increase of the negative surface potential of mitochondrial membranes, as calculated from the dissociation constant of fluorescent probes, 8‐anilino‐1‐naphthalene sulphonate and ethidium bromide, and by a decrease of the apparent K
m‐value of mitochondrial monoamine oxidase. Protein phosphorylation, the increase of the negative surface potential and the decrease of apparent K
m of monoamine oxidase are greatly potentiated by cytoplasmic protein kinases in the presence of cyclic AMP.
Reconstruction of tRNAPhe molecules from the fragments by linkage with T‐4 RNA ligase in double‐stranded regions
Authors: Boutorin A.S. , Vassilenko S.K. , Baklanov M.M. , Nechaev Yu.S.
Published: July 2002

Phenylalanine‐specific tRNA from yeast was hydrolysed with cobra venom ribonuclease in the double‐stranded regions and the fragments isolated. The ‘dissected’ molecules with nicks in positions 28 and 41 were reconstructed from supplementary fragments and treated with T‐4 RNA ligase. A phosphodiester bond between two fragments was formed when the fragment combination (1–28) + (29–76) was used. A strong discrimination in the ligation yield between different nick positions in the same helix is shown.
Stability of 2′ – 5′)oligoriboadenylates in various sera
Authors: Vilček Š. , Vrtiak O.J. , Smrt J. , Jurovčík M.
Published: July 2002

Avian and mammalian sera were found to contain an enzyme activity degrading 2–5A oligonucleotides. The most extensive degradation of the A2′p5′ A was observed in chicken serum. Degradation of this compound is not affected by the presence of cAMP, dsRNA, Mg2+, but is significantly inhibited by EDTA. The enzyme activity described is not inactivated by heating to 56°C for 30 min. The 5‐mU3′p5′ A has also been degraded in chicken serum
Signal recognition particle triggers the translocation of storage globulin polypeptides from field beans (Vicia faba L.) across mammalian endoplasmic reticulum membrane
Authors: Bassüner Ronald , Wobus Ulrich , Rapoport Tom A.
Published: July 2002

Hybridization‐selected mRNAs coding for individual storage globulin polypeptides of field beans (Vicia faba L.) were translated in a cell‐free system. Added mammalian signal recognition particle (SRP) recognizes cleavable signal peptides of the major vicilin and both legumin polypeptide precursors and induces translational arrest. The latter can be released by potassium‐washed membranes (K‐RM) leading to shortened polypeptides protected against proteases. Thus, SRP and K‐RM function in a similar way with plant polypeptides as described for mammalian secretory proteins [(1981) J. Cell Biol. 91, 557–561]. Obviously, the initial steps in the biosynthesis and processing of plant storage globulin polypeptides are principally identical to those of animal secretory proteins.
5′‐Cleavage site of D. melanogaster 18 S rRNA
Authors: Simeone A. , Boncinelli E.
Published: July 2002

We determined the nucleotide sequence of the DNA region around the 5′‐terminus of 18 S rRNA in two cloned rDNA gene units of Drosophila melanogaster. The 5′‐base is within a sequence CATTATT which is present also at the 3′‐terminus of the 18 S rRNA coding region. In this case it is known that the situation is CATTA3′ · TT. With various methods are determined that the precise 5′‐cleave site is CATT·5′ATT.
Quantitative characterization of pyrimidine dimer excision from UV‐irradiated DNA (excision capacity) by cell‐free extracts of the yeast Saccharomyces cerevisiae
Authors: Bekker Michail L. , Kaboev Oleg K. , Akhmedov Alexander T. , Luchkina Ludmila A.
Published: July 2002

Cell‐free extracts from wild‐type yeast (RAD+) and from rad mutants belonging to the RAD3 epistatic group (rad1‐1, rad2‐1, rad3‐1, rad4‐1) contain activities catalyzing the excision of pyrimidine dimers (PD) from purified ultraviolet‐irradiated DNA which was not pre‐treated with exogenous UV‐endonuclease. The level of these activities in cell‐free extracts from rad mutants did not differ from that in wild‐type extract and was close to the in vivo excision capacity of the latter calculated from the LD
37 (about 104 PD per haploid genome).
Hemoglobin Aichi [α50(CE8) His → Arg]: a new slightly unstable hemoglobin variant discovered in Japan
Authors: Harano Teruo , Harano Keiko , Shibata Susumu , Ueda Satoshi , Mori Hiroo , Seki Masami
Published: July 2002

A new abnormal hemoglobin, Hb Aichi [α50(CE8) His → Arg], was discovered in a young Japanese man. This variant was isoelectrofocussed between Hb A and Hb A2 and amounted to about 21% of the total hemoglobin in the hemolysate. This hemoglobin showed normal oxygen affinity but slight instability.
Analysis of the effect of bezafibrate on the oxygen dissociation curve of human hemoglobin
Authors: Wootton Raymond
Published: July 2002

Analysis of the effects of a range of concentrations of the antihyperlipoproteinemia drug, bezafibrate, on the oxygen dissociation curve of dilute hemoglobin solutions indicates a 4:1 binding stoichiometry with a site binding constant of 434 molt‐1 for deoxyhemoglobin. Analysis of the combined effects of a range of bezafibrate and 2,3‐diphosphoglycerate (DPG) concentrations indicates that 2 of the 4 bezafibrate sites are in the vicinity of the DPG binding site, and competitive with DPG binding, and 2 of the sites are remote from the DPG binding site.
Temperature‐induced ultraviolet difference absorption spectrometry for determination of enthalpy changes
Authors: Loontiens Frank G. , Dhollander Gaby
Published: July 2002

Raising the temperature in a single mixture of a lectin and a chromophoric glycoside allows determination of the binding enthalpy. This is made possible by continuously monitoring the displacement of the complex from its equilibrium concentration with a sensitive difference absorption spectrophotometer. The method is illustrated with the following lectins: concanavalin A, soybean agglutinin, peanut agglutinin and Erythrina cristagalli agglutinin. The ligands are 4‐methylumbelliferyl glycosides. The binding enthalpies found range from −60 kJ · mol−1 for the Galß1 → 3GalNAc‐ßglycoside and peanut agglutinin to −30 kJ · mol−1 for a monosaccharide glycoside and the other lectins.
Sequence data concerning the protein core of the cartilage proteoglycan monomers
Authors: Périn Jean-Pierre , Bonnet François , Jollès Jacqueline , Jollès Pierre
Published: July 2002

The present report develops our previous structural data concerning the cyanogen bromide fragments from the bovine nasal cartilage proteoglycan monomers. Among the reported sequences a Met‐Ile‐Trp‐His sequence was characterized, useful for future studies devoted to the molecular cloning of the proteoglycan monomers.
Evidence for a two‐step process in prostaglandin secretion
Authors: Thomas Jeannie Marie-France , Hullin Françoise , Chap Hugues , Douste-Blazy Louis
Published: July 2002

Cultured endothelial cells (EC) from human umbilical vein were incubated with [U‐14C]arachidonic acid (AA) followed by a challenge with thrombin (2 ) or calcium ionophore A23187 (5 μM) for 0.5–10 min at 37°C. In both cases, AA was rapidly liberated from phospholipids and converted into prostaglandin I2 (PGI2), as determined by the radioactivity of the stable derivative 6‐keto‐PGF1α. Maximal liberation of AA and synthesis of PGI2 were‐achieved within 2 min, but the two compounds first accumulated in EC prior to their release into supernatants. This finding, which was never reported before, raises the question of the mechanism of AA and PG release through the cell membranes and offers a convenient model to investigate this still obscure process.
Hypomethylation of DNA in meiotic and postmeiotic rooster testis cells
Authors: Rocamora Nativitat , Mezquita Cristóbal
Published: July 2002

To study whether changes in methylation of DNA are related to the structural and functional changes that chromatin undergoes throughout rooster spermatogenenis, we analyzed, by high‐performance liquid chromatography, the 5‐methylcytosine content of DNA purified from rooster testis cell nuclei at successive stages of the cell differentiation process. The DNA of meiotic and postmeiotic cells appears partially under‐methylated, containing approximately 30% less methylcytosines than the DNA obtained from premeiotic and somatic cells.
Structural differences between active and inactive 30 S ribosomal subunits revealed by RNA‐protein crosslinking
Authors: Chiaruttini Claude , Milet Michèle , Hayes Donal
Published: July 2002

30 S protein‐16 S rRNA crosslinking by reaction with 1‐ethyl‐3‐dimethylaminopropylcarbodiimide is more efficient in the active than in the inactive form of the E. coli 30 S ribosomal subunit. This difference is particularly striking in the case of protein S8.
Deoxyribonuclease activities of wheat seedlings
Authors: Jones Matthew C. , Boffey Stephen A.
Published: July 2002

Triticum aestivum DNase assay
DNA isolation
EDTA‐activated DNase
In vitro enzymatic methylation of DNA substituted by N‐2‐aminofluorene
Authors: Pfohl-Leszkowicz A. , Fuchs R.P.P. , Dirheimer G.
Published: July 2002

Both the initial velocity and the overall methylation of DNA substituted by aminofluorene, by a rat liver DNA(cytosine‐5‐)‐methyltransferase, are increased as compared to native DNA. The K
m and V
max of the modified DNA for the enzyme increase as a function of the extent of modification. The carcinogen may induce a secondary structure favouring the ‘walking’ of the enzyme along the DNA. The hypermethylation caused by this carcinogen could have a significance in gene activity, cellular differentiation and cancer induction.
Stimulatory effects of adenosine, adenosine analogs and insulin on adipose tissue lipoprotein lipase activity and their prevention by phosphodiesterase inhibitors
Authors: Bourdeaux Anne-Marie , Nordmann Roger , Giudicelli Yves
Published: July 2002

Adenosine and its ‘Ri’‐ and ‘P’‐site analogs, N
6‐phenylisopropyladenosine and 2'‐deoxyadenosine, stimulate, like insulin, lipoprotein lipase (LPL) activity in adipose tissue, an effect which is suppressed by cycloheximide. However, adenosine and its analogs do not potentiate the effects of submaximal insulin concentrations. As addition of cyclic AMP phosphodiesterase inhibitors abolishes the LPL stimulatory effects of insulin, adenosine and its analogs, this study suggests that these LPL effects are mediated through common mechanisms which are likely a decrease in cyclic AMP and an increase in LPL biosynthesis.
Influence of an actin‐modulating protein from smooth muscle on actin‐myosin interaction
Authors: Strzelecka-Gotaszewska Hanna , Hinssen Horst , Sobieszek Apolinary
Published: July 2002

Smooth muscle
Actin‐modulating protein
Actin‐myosin interaction
Lysosomal thyroid hormone 5'‐deiodinase
Authors: Colquhoun Eric Q. , Thomson Roslyn M.
Published: July 2002

Lysosome
Deiodination
Iodothyronine
Detergent
Dithiothreitol
Membrane
Stimulation of protein accumulation in HeLa cells by inhibitors of DNA replication
Authors: Menozzi F.D. , Hanotte O. , Miller A.O.A.
Published: July 2002

Incubation of HeLa cells for 24 h with either hydroxyurea (HU), aphidicolin (APHI), thymidine (T) or butyrate (BU), substances used to inhibit replication and accumulate cells at the G1/S interphase, followed by the elimination of the inhibitor and the addition of iron to the growth medium, results in an immediate (HU, APHI, T) or slightly delayed (BU) increased accumulation (18–24‐fold higher than the basal level) of ferritin. Under the same experimental circumstances, 5‐azacytidine is without effect. As a result of the action of these inhibitors on the structure of DNA, it is proposed that ferritin genes remain accessible to RNA polymerase allowing the accumulation in the cytoplasm of mature ferritin mRNA ready to be mobilized by iron for the production of ferritin molecules.
The N‐terminal sequence of albumin Redhill, a variant of human serum albumin
Authors: Hutchinson D.W. , Matejtschuk P.
Published: July 2002

Albumin Redhill, a variant human albumin, has been isolated by fast protein liquid chromatofocusing. The N‐terminal sequence of this protein corresponded to that of albumin A except that one additional arginine residue was attached to the N‐terminus.
Biosynthesis of intestinal microvillar proteins
Authors: Danielsen E.Michael , Sjöström Hans , Norén Ove
Published: July 2002

The effect of chloroquine on the biosynthesis of pig intestinal aminopeptidase N (EC 3.4.11.2) was studied by labelling with [35S]methionine in organ cultured mucosal explants. The lysosomotropic agent did not alter the molecular size of either the transient or the mature form of the enzyme and did not markedly influence the relative intracellular distribution of the two forms. The microvillar expression of aminopeptidase N during labelling periods of 80–120 min was found to be unaffected by chloroquine. Together these data indicate that pH neutralization of the acidic compartments of the cell bears no consequence on the intracellular transport of the newly synthesized microvillar enzyme. This suggests that the acidic compartments are not involved in the post‐Golgi transport and that this, in turn, probably occurs via a constitutive rather than a regulated pathway.
Chromaffin granule‐cytoskeleton interaction
Authors: Morita Kyoji , Pollard Harvey B.
Published: July 2002

The influence of cytoskeletal elements on the chromaffm granule function was studied using a model system consisting of purified granule membranes and F‐actin. The membrane ATPase was partially inactivated by incubation at 37 °C, and this inactivation was prevented by adding F‐actin. The stabilizing action of F‐actin on the ATPase was abolished by adding DNase I. Detergent‐solubilized ATPase was more rapidly and profoundly inactivated, but was not stabilized by F‐actin. The stabilization of ATPase by F‐actin may be due to the cross‐linking of granule membranes with F‐actin and the native structure of the granule membrane may be required for preserving the stability of membrane ATPase. These findings thus suggest the possibility that the interaction of microfilaments with chromaffin granules may influence the function of chromaffin granules within the cell.
Lack of nucleotide cleavage on the binding of G‐actin‐ATP to plasma gelsolin
Authors: Harris Harriet E.
Published: July 2002

G‐Actin‐ATP bound to plasma gelsolin to form a 2:1 complex. The complex contained approximately equivalent amounts of nucleotide and actin. More than 84% of this nucleotide was ATP. Half of the bound nucleotide was displaced by cold chase and the remainder did not exchange, implying that the two actins in the complex are not equivalent.
Incorporation of isoleucine into protein by a soluble fraction from spermatozoa
Authors: Hashizume Shuichi
Published: July 2002

A heat‐labile, non‐dialyzable factor(s) in soluble fractions from porcine, bull, rabbit and cock spermatozoa was found to incorporate the radioactivity of [14C]isoleucine into a 95°C CCl3COOH‐insoluble fraction. The incorporation required ATP, Mg2+, casein and 2‐mercaptoethanol. Trypsin and a‐chymotrypsin inhibited the incorporation, while RNase A and DNase I did not. A mixture of 19 amino acids other than isoleucine had no effect on the incorporation. The reaction product was identified as protein. The incorporated moiety was the isoleucyi moiety of isoleucine and it retained a free α‐amino group in the product protein. Some other characteristics of this incorporation are also described.
Changes in the size of isolated chromaffin granules in ATP‐evoked catecholamine release
Authors: Warashina Akira
Published: July 2002

The average size of chromaffin granules isolated from bovine adrenal medullae was analyzed by a quasielastic laser light scattering method. The granule diameter increased by a factor of 1.3 by addition of Mg‐ATP in the medium. The ATP effect was completely suppressed in the presence of an anion transport blocker (SITS), and partly depressed by a proton transport blocker (DCCD).
Plasma membrane transglutaminase and cornified envelope competence in cultured human keratinocytes
Authors: Schmidt Rainer , Reichert Uwe , Michel Serge , Shroot Braham , Bouclier Martine
Published: July 2002

When confluent cultures of the transformed human keratinocyte line SV‐K14 are shifted to serum‐free medium the cells achieve, within 4 days, the ability to synthesize a cornified envelope after challenge with the Ca2+ ionophore A23187. During these 4 days the enzyme transglutaminase (EC 2.3.2.13), which catalyses the cross‐linking of different envelope precursor proteins, is partially transferred from the cytosolic pool into the plasma membrane. The association of the enzyme with the plasma membrane proves to be an essential step in the envelope formation since a direct correlation between plasma membrane‐bound transglutaminase and envelope competence is observed. Retinoids block the insertion of the enzyme and therefore prevent envelope formation.
3'‐Fluoro‐2',3'‐dideoxyribonucleoside 5'‐triphosphates: terminators of DNA synthesis
Authors: Chidgeavadze Zurab G. , Scamrov Andrei V. , Beabealashvilli Robert Sh. , Kvasyuk Eugenii I. , Zaitseva Galina V. , Mikhailopulo Igor A. , Kowollik Gotthard , Langen Peter
Published: July 2002

It is shown that dNTP(3'F) are terminators of DNA synthesis and may serve as very effective tools for DNA sequencing with E.coli DNA polymerase I and AMV reverse transcriptase. The dNTP(3'F) are found to be chain terminator substrates for calf thymus terminal deoxyribonucleotidyl transferase but not for calf thymus DNA polymerase α. The optimal dNTP(3'F) concentration for DNA sequencing by DNA polymerase I is found to be an order of magnitude lower than that of ddNTPs. dNTP(3'F) produce a more clear sequence pattern than do ddNTPs.
Differences in mechanisms of modulation between rat liver cholesterol 7α‐hydroxylase and HMG‐CoA reductase
Authors: Lidström-Olsson Bodil
Published: July 2002

Cholesterol 7α‐hydroxylase
HMG‐CoA reductase
Kinase
Phosphoprotein phosphatase
Glutathione
The influence of tertiary structure on secondary structure prediction
Authors: Garratt Richard C. , Taylor William R. , Thornton Janet M.
Published: July 2002

The secondary structure prediction algorithm of Garnier et al. [(1978) J. Mol. Biol. 120, 97‐120] has been used for 16 proteins whose structures are dominated by β‐sheet. Comparisons of the predicted structures with those defined by the algorithm of Kabch and Sander [(1983) Biopolymers 22, 2577‐2637] shows that for β‐sheet residues, the quality of prediction falls markedly with increasing residue accessibility. 2 sub‐classes of β‐residues have been distinguished on the basis of hydrogen bonding patterns, and the distribution of amino acid types within each sub‐class found to be quite different. Accordingly, Chou and Fasman P
β‐type parameters for these previously indistinguished states have been derived.
Stable secondary structures at the 3'‐end of the genome of yellow fever virus (17 D vaccine strain)
Authors: Grange Thierry , Bouloy Michèle , Girard Marc
Published: July 2002

The sequence of the 3'‐terminal 565 nucleotides of yellow fever virus has been determined from a cloned cDNA. Several structures are detectable: three tandemly repeated sequences, a series of inverted repeats and a stable secondary structure involving the 3'‐terminal 120 nucleotides.
The EPR spectrum and orientation of cytochrome b‐563 in the chloroplast thylakoid membrane
Authors: Bergström Jörgen
Published: July 2002

The EPR spectrum of cytochrome b‐563 in spinach chloroplasts shows that both hemes of the cytochrome are in a low‐spin state with g
z = 3.5. The orientation of the two heme planes is found to be perpendicular to the thylakoid membrane plane in magnetically aligned chloroplasts. This may be relevant for the function of cytochrome b‐563, e.g., in electron transport coupled to proton translocation.
Isolation and characterization of cytochrome b‐562 from cytochrome b‐c1 comlex of the photosynthetic bacterium Rhodopseudomonas sphaeroides R‐26
Authors: Iba Koh , Takamiya Ken-ichiro , Arata Hiroyuki
Published: July 2002

Cytochrome
b‐562 Cytochrome b‐C1
complex Rhodopseudomonas sphaeroides
Formate dehydrogenase from Clostridium pasteurianum
Authors: Prince Roger C. , Liu Chi-Li , Morgan T.Vance , Mortenson Leonard E.
Published: July 2002

Formate dehydrogenase from Clostridiun pasteurianum catalyses the interconversion of CO2, and formate. It is a complex enzyme, containing molybdenum, iron, acid‐labile sulfur and pterin. Redox potentiometry and EPR analysis reveal two spectrally and thermodynamically distinct iron‐sulfur clusters, with g 1.87, 1.95 and 2.05 (Em8
‐318 mV) and g 1.92 and 2.05 (Em8
‐372 mV), both present at approx. 0.3 spins per enzyme. There is also a free radical signal centered near g 2.005 which we attribute to the pterin, perhaps in its anionic semiquinone form. This signal disappears on oxidation (Em8
‐150 mV), but is not reduced further at pH 8. It is present at approx. 0.8 spins per enzyme. No EPR signals attributable to the molybdenum were detected.
Crosslinking of actin filaments is caused by caldesmon aggregates, but not by its dimers
Authors: Sobue Kenji , Takahashi Katsuhito , Tanaka Toshihiko , Kanda Keiko , Ashino Nobuhiko , Kakiuchi Shiro , Maruyama Koscak
Published: July 2002

Caldesmon
Actin‐associated protein
Calmodulin‐binding protein
Actin‐crosslinker
Chicken gizzard
Cyclic AMP and c‐myc gene expression in PY815 mouse mastocytoma cells
Authors: Le Gros J. , De Feyter R. , Ralph R.K.
Published: July 2002

The possibility was examined that inhibition of growth of PY815 mouse mastocytoma cells by N
6,O
2'‐dibutyryladenosine 3',5'‐cyclic monophosphate (DB cyclic AMP) results from inhibition of c‐myc gene expression. Temporary increases in c‐myc RNA which occurred soon after DB cyclic AMP treatment and upon removal of the drug were not consistent with direct inhibition of c‐myc gene expression by DB cyclic AMP. The increases in c‐myc RNA coincided with the passage through, or accumulation of cells in late G1 ‐ early S phase. It is proposed that cyclic AMP may stimulate c‐myc gene expression which normally occurs only in late G1 ‐ early S phase in PY815 cells and that cyclic AMP prevents c‐myc expression in cells at other phases of the cell cycle by inhibiting their progression past a cyclic AMP‐sensitive restriction point in early G1 phase.
Conformational change of 50 S ribosomes on enzymatic binding of phenylalanyl‐tRNA
Authors: Srivastava S. , Burma D.P.
Published: July 2002

Tight couple 70 S ribosmes are converted to loose couple ones on enzymatic binding of phenylalanyl‐tRNA. Enzymatic binding at 0°C as well as nonenzymatic binding does not lead to any change. Further, no change takes place when the P site is occupied by N‐acetylphenylalanyl‐tRNA. Loose couple 70 S ribosomes are not affected by either enzymatic or nonenzymatic binding of phenylalany‐tRNA.
Identification of yeast 60 S ribosomal proteins crosslinked to rRNA by 2‐iminothiolane
Authors: El-Baradi T.T.A.L. , Raué H.A. , Linnekamp M. , Planta R.J.
Published: July 2002

Saccharomyces carlsbergensis 60 S ribosomal subunits were treated with the hetero‐bifunctional crosslinking agent 2‐iminothiolane and then subjected to mild UV irradiation to introduce protein‐rRNA crosslinks. The major crosslinked products were identified as proteins L2, L3, L5, L19 and L23 of which L5 was found to be crosslinked at a 3–5‐fold higher efficiency than the other four. Several additional proteins were crosslinked to a detectable but much lower extent.
Kinetics of electron transfer in reaction center‐cytochrome o proteoliposomes
Authors: Moser Christopher C. , Matsushita Kazunobu , Robertson Dan E. , Kaback H.Ronald , Leslie Dutton P.
Published: July 2002

A proteoliposome hybrid protein system consisting of photosynthetic reaction centers (RC) from Rhodopseudomonas sphaeroides, cytochrome o from E. coli and ubiquinone‐8 has been reconstituted to study the mechanism of O2 reduction and the generation of Δs̃mH+ in cyt. o. Steady‐state illumination leads to O2 uptake and the generation of an interior negative ΔΨ. A rapid flash of light induces a single turnover of each RC, and the resultant pulse of quinol leads to quinonoid inhibitor‐sensitive millisecond reduction kinetics and cyanide‐sensitive re‐oxidation kinetics of cyt o. The b hemes are similar on a kinetic, redox and α‐band spectral basis.
Similarities between a conserved sequence element of homoeo boxes and other genes
Authors: Tsonis Panagiotis A. , Lambris John D.
Published: July 2002

We report here the homology of different genes with an 18‐nucleotide sequence element derived from a conserved region of the homoeo boxes. Possible evolutionary relationships are discussed.
Differential prooxidative effect of adult and fetal hemoglobin
Authors: Valenzuela Alfonso , Guerra Ricardo , Lazcano Laura , Canãs Patricio
Published: July 2002

Human fetal hemoglobin assayed in a peroxidizing system shows an increased prooxidative effect when compared to human adult hemoglobin. This effect is related only to the oxyhemoglobin form since both fetal and adult methemoglobins did not show any prooxidative effect. The prooxidative effect of the oxyhemoglobin form is ascribed to its increased sensitivity to form Superoxide free radicals when transformed to the methemoglobin form. It is proposed that the structure of the heme pocket of fetal oxyhemoglobin enhances free radical release when compared to adult oxyhemoglobin. This difference may be important in some hematological disorders presented by the newborn.
Sequence rearrangements may alter the in vivo superhelicity of recombinant plasmids
Authors: Amster O. , Zamir A.
Published: July 2002

Electrophoretic resolution of topoisomers was used to compare the in vivo superhelicity of recombinant plasmids containing a fragment of cDNA for an immunoglobulin light chain, cloned in the two possible orientations into the BamHI site of pBR313 or pBR322. Previously, frequent transpositions of IS1 or IS5 were observed into the sequence upstream to the cloned fragment in recombinants in one orientation [(+) plasmids] but not in recombinants in the opposite, (−) orientation [(1982) Nucleic Acids Res. 10, 4525‐4542]. The results of the present analyses show that, on average, (−) plasmids are less negatively supercoiled than (+) plasmids, or pBR322. These results suggest that primary sequence rearrangements in plasmids could affect their in vivo topological state, and consequently, perhaps, their effectiveness as recipients of transposable elements.
Formation of metabolites of [Arg8]vasopressin (AVP) by brain peptidases
Authors: Wang Xin-Chang , Burbach J.Peter H.
Published: July 2002

[Cyt6]AVP‐(3–9), an intermediate in the metabolism of AVP‐(1–9) in vitro, was used to investigate the mechanism of formation of centrally active AVP metabolites. Exposure of [Cyt6]AVP‐(3–9) to rat brain membranes resulted in formation of [Cyt6]AVP‐(4–9),‐(5–9), [pGlu6,Cyt6]AVP‐(4–9) and AVP‐(3–5), which were isolated and chemically identified. Products derived from cleavage of the C‐terminus of the substrate were absent. Time‐course experiments further indicated that the conversion process is predominantly mediby an aminopeptidase‐like mechanism. The conversion of [Cyt6]AVP‐(3–9) by membranes from hippocampus, amygdala and septum was quantitatively and qualitatively similar. The results point to a major role of aminopeptidase activity in the metabolic conversion of AVP and the formation of centrally active AVP metabolites.