bluuebunny/crossref_metadata_2025 huggingface dataset:
Some properties of a mitochondrial endonuclease from yeast
Authors: Morosoli R. , Lusena C.V.
Published: December 2009

A mitochondrial endonuclease from Saccharomyces cerevisiae was previously shown to cut both strands of native DNA at opposite or nearby sites. The present studies demonstrate that the endonuclease activity is dependent on the strength of the hydrogen bonds between the DNA strands; the activity was measured at different ionic strengths, with substrates of different base compositions and also with DNA in which the double helix has been locally destabilized by ultraviolet irradiation, by depurination, and by single-stranded nicks. The activity is 30% greater with mitochondrial DNA (mt-DNA) than with nuclear DNA. At 0.08 ionic strength, the relative activities with double-stranded polydeoxyribonucleotides are 2.4:1:0.6 for poly(dA)∙poly(dU): poly(dA)∙poly(dT): poly(dG)∙poly(dC). Increasing ionic strength decreases similarly me activity with poly(dA)∙poly(dU) and poly(dA)∙poly(dT), but has little effect with poly(dG)∙poly(dC). The greater activity with poly(dA)∙poly(dU) than with poly(dA)∙poly(dT) was confirmed with nick-translated mt-DNA and with DNA synthesized in isolated mitochondria using [3H]TTP and [3H]dUTP in both cases. The endonuclease cuts modified DNA preferentially in the thymine dinner regions, at the apurirtic sites, and at sites opposite to nicks. The possible involvement of this endonuclease in the degradation of mitochondrial DNA during "petite" induction is discussed.
An immunological study of the interaction of ligands with pyruvate kinase of Neurospora crassa
Authors: Kapoor M. , Bishop M.
Published: December 2009

Antibodies against pyruvate kinase of Neurospora crassa, induced in rabbits, were used to monitor the interaction of ligands with this enzyme. The technique of microcomplement fixation was employed to probe for conformational alterations elicited by binding of substrates (phosphoenolpyruvate (PEP) and adenosine diphosphate), the allosteric activator (fructose 1,6-diphosphate), and the inhibitor (valine). On binding of PEP and valine to pyruvate kinase a pronounced reduction in the extent of complement fixation was observed. The second substrate, ADP, had no effect while FDP elicited a moderate suppression of complement fixation. These results suggest that as a consequence of conformational changes induced by PEP and valine, some antigenic determinants on the surface of pyruvate kinase are rendered inaccessible to the antibodies.
Analysis of enzymatically released peptides by revese-phase high performance liquid chromatography from picomole amounts of apolipoproteins separated on polyacrylamide isoelectric focusing gels
Authors: Pereira Leo V. , Dolphin Peter J.
Published: December 2009

Methods were developed for the peptide analysis of individual isoproteins of human apolipoproteins separated on urea–polyacrylamide isoelectric focusing (IEF) gels. After IEF the proteins were fixed in the gel matrix by trichloroacetic acid precipitation. Low molecular weight contaminants, including ampholytes, were removed and the proteins were chemically desialylated. Enzymatic digestions with L-1-tosyl-2-phenylethylchloromethyl ketone – trypsin, chymotrypsin, or with thermolysin were accomplished within the gel matrix. The proteolytically released peptides were analyzed by reverse-phase high performance liquid chromatography. These methods facilitated the comprehensive analysis of protein structural differences between individual isoproteins of apolipoproteins in duplicate with as little as 1–2 nmol of each isoprotein, without the use of radiolabels. Human apolipoproteins A-I, C, and E were analysed by these methods.
Molecular properties of fumarate reductase isolated from the cytoplasmic membrane of Escherichia coli
Authors: Robinson John J. , Weiner Joel H.
Published: December 2009

Fumarate reductase, purified from the cytoplasmic membrane of Escherichia coli, has been cross-linked with the bifunctional reagent dimethylsuberimidate and shown to exist as an αβ dimer of polypeptides of molecular weights 69 000 and 25 000 in a 1:1 molar ratio. The protein has an s20,W of 7.67S and a D20,W of 6.5 × 10−7 cm2/s. The purified enzyme contained 4–5 mol of nonheme iron and 4–5 mol of acid labile sulfur while the visible absorption spectrum showed a broad peak between 400 and 470 nm owing to the presence of an Fe–S centre and 8α[N-3]histidyl FAD. Fumarate reductase activity was readily inhibited by the sulfhydryl reagents 5,5′-dithiobis-(2-nitrobenzoic acid), p-chloromercuribenzoate, and iodoacetamide. Using 5,5′-dithiobis-(2-nitrobenzoic acid) sulfhydryl group modification was followed as a function of enzyme activity. A single cysteine residue was shown to be required for activity and this essential sulfhydryl group was located in the 69 000 dalton subunit. The amino acid composition of E. coli fumarate reductase was similar to the succinate dehydrogenases from beef heart mitochondrion and Rhodospirillum rubrum.
Radioimmunoassay for the antifreeze polypeptides of the winter flounder: seasonal profile and immunological cross-reactivity with other fish antifreezes
Authors: Slaughter Don , Hew Choy L.
Published: December 2009

The polymerization of winter flounder antifreeze polypeptide (AFP) with glutaraldehyde to increase its antigenicity and the conjugation of the AFP to bovine serum albumin so that the AFP could carry a radioiodine label have allowed the development of a convenient and reliable radioimmunoassay (RIA) for the antifreeze. A seasonal concentration profile of serum AFP as determined by the RIA corresponded closely with its activity profile. Winter serum concentrations of AFP measured by the RIA (7–11 mg/mL) agreed well with antifreeze recovery from Sephadex G-75 chromatography of serum (6–10 mg/mL), but less so with concentration estimates reported from activity measurements (12–25 mg/mL) (Petzel, D. H., Reisman, H. M. &DeVries, A. L. (1980) J. Exp. Zool. 211, 63–69). A small but measurable immunological cross-reactivity was detected between the antiflounder AFP and other fish antifreeze polypeptides. Such cross-reactivity was quite unexpected considering the large compositional and structural differences among the various AFP and its significance remains unclear.
Growth of interscapular brown adipose tissue in cold-acclimated hypophysectomized rats maintained on thyroxine and corticosterone
Authors: Fellenz Mathias , Triandafillou Joan , Gwilliam Cynthia , Himms-Hagen Jean
Published: December 2009

Brown adipose tissue (BAT) of rats is known to grow in response to acclimation to cold. The growth is accompanied by changes in mitochondrial polypeptide composition (an increase in the relative proportion of a polypeptide of molecular weight 32 000, known to be associated with the thermogenic proton conductance pathway). The mediator of the change in mitochondrial polypeptide composition is unknown. The objective of these experiments was to find out whether any of the pituitary hormones might be the mediator. Treatment of rats with growth hormone failed to alter BAT size or mitochondrial polypeptide composition. BAT grew and the change in BAT mitochondrial polypeptide composition occurred in cold-acclimated hypophysectomized rats, maintained on thyroxine and corticosterone to ensure their survival in the cold. It is concluded that none of the pituitary hormones is the mediator for the cold-induced change in BAT mitochondrial polypeptide composition or is required to exert a direct effect on BAT for cold-induced BAT growth to occur. It also seems unlikely that more than a maintenance amount of glucocorticoids is required for normal cold-induced growth of BAT; these hormones are thus also unlikely to mediate the change in BAT mitochondrial polypeptide composition. The requirement for no more than a maintenance amount of thyroxine for BAT growth and for the cold-induced change in BAT mitochondrial polypeptide composition confirms previous conclusions drawn from studies on cold-acclimated thyroidectomized rats.
Tonin as activator of renin
Authors: Gutkowska Jolanta , Corvol Pierre , Thibault Gaétan , Genest Jacques
Published: December 2009

Tonin, a new serine protease, found in high concentration in rat submaxillary glands, leads to a significant activation of human amniotic fluid renin. The optimum pH on renin activation by tonin was found at pH 6.0. The reaction was time dependent and the initial rate of angiotensin I generation was constant up to 2 h. The two amniontic fluid samples studied showed an increase in renin activity after incubation with tonin to about five times the control level (268 to 1240 pmol∙h−1∙mL−1 and 1490 to 7480 pmol∙h−1∙mL−1).
The effect of ultraviolet radiation on early stages of activation of human lymphocytes: inhibition is independent of effects on DNA
Authors: Castellanos Gustavo , Owens Trevor , Rudd Christopher , Bladon Trevor , Setterfield George , Kaplan J. Gordin
Published: December 2009

Low doses (30–84 ergs/mm2, 1 erg = 107 J) of ultraviolet radiation (UV) caused severe inhibition of the proliferation of human lymphocytes in vitro. Greatest inhibition was produced when resting cells were irradiated immediately prior to stimulation with concanavalin A (Con A); this was true whether activation was measured by the incorporation of labelled leucine, uridine, or thymidine. If UV was applied at 44 h after culture in presence of Con A, the incorporation of [3H]thymidine measured 4 h later was seen to be inhibited but transcription and translation were scarcely affected. UV, applied after the appearance of the Con A induced thymidine transport system, did not inhibit its function. The disaggregation of chromatin and increase in nuclear volume characteristic of, and essential to, the proliferative response of lymphocytes were completely inhibited if the cells were irradiated before mitogen was added to the cultures, but were unaffected if irradiation occurred after 16 h of culture in presence of Con A. Cells irradiated with 84 ergs/mm2 at the onset of culture with mitogen did not show the early increase of cation pump function which is a characteristic of stimulated lymphocytes, when this was measured by means of 86Rb uptake after 2–4 h culture. The mitogen-stimulated activation of cation pump function has previously been shown to be unaffected by concentrations of cycloheximide and actinomycin D which produce virtually complete inhibition of protein and RNA synthesis, respectively. The major inhibitory effect of UV treatment of lymphocytes at onset of culture with Con A is therefore not on DNA or on DNA synthesis, but on some component(s) of the early activation process, possibly at the cell periphery; inactivation of this component prevents cells from proceeding into later stages of the proliferative pathway.
Dissociation and characterization of pilin isolated from Pseudomonas aeruginosa strains PAK and PAO
Authors: Watts Tania H. , Kay Cyril M. , Paranchych William
Published: December 2009

Pili isolated from Pseudomonas aeruginosa strains PAK and PAO have been dissociated into subunits using the detergent octyl glucoside. Circular dichroism studies indicated that no change in protein conformation occurs as a result of this treatment. Ultracentrifugation measurements showed that both pilins have a Stokes radius of 21 Å (1 Å = 0.1 nm) corresponding to an axial ratio of between 3:1 and 5:1, when approximated as prolate or oblate ellipsoids. Sedimentation equilibrium measurements show that even at low protein concentrations the pilin–detergent complex exists as a mixture of monomers and dimers.
The effect of anoxia on anthracycline-induced DNA damage in the RPMI-6410 human lymphoblastoid cell line
Authors: Brox L. , Gowans B. , To R. , Belch A.
Published: December 2009

The alkaline elution procedure developed by Kohn and co-workers was used with the RPMI-6410 cultured human lymphoblastoid cell line to examine the hypothesis that anthracycline-induced DNA strand scission is mediated by oxygen- or superoxide-derived free radicals. Hypoxia was induced by gassing with nitrogen containing 5% carbon dioxide and less than 4 ppm oxygen. Alkaline elution studies showed hypoxia was induced, as the oxygen enhancement ratios for DNA strand breaks was 2.4 and 2.6 for the 250 R ± oxygen and the 500 R ± oxygen (1 R = 2.58 × 10−4 C/kg) experiments, respectively. The pattern of adriamycin-induced DNA strand breaks and cross-linking was not affected by hypoxia with 1-h adriamycin exposures between 0.05 and 1.0 μg/mL. Similarly, 1-h exposures of N-trifluoroacetyladriamycin-14-valerate at 3 or 10 μg/mL gave essentially identical alkaline elution profiles in the presence or absence of oxygen. These results do not support the hypothesis that oxygen-derived radicals play a primary role in anthracycline-induced DNA strand breakage.
Biosynthesis of microsomal phospholipids and mitochondrial polyglycerophosphatides in rapidly sedimenting endoplasmic reticulum
Authors: Stuhne-Sekalec L. , Stanacev N. Z.
Published: December 2009

Rapidly sedimenting endoplasmic reticulum (RSER), which is known to be a complex between endoplasmic reticulum and mitochondria, was isolated from rat liver and purified through a sucrose density gradient by centrifugation according to a well established procedure previously published by G. C. Shore and J. R. Tata. This complex was characterized by microsomal (NADPH–cytochrome c reductase) and mitochondrial (succinate–cytochrome c reductase and NADP–isocitrate dehydrogenase) marker enzymes and was examined for the ability to synthesize microsomal lipids and mitochondrial polyglycerophosphatides. Results of these experiments showed that the RSER is capable of synthesizing key microsomal lipids, i.e., phosphatide acid, phosphatidylcholine, and neutral lipids, as well as mitochondrial phosphatidylglycerophosphate and phosphatidyiglycerol. Furthermore, the level of synthesis of these lipids paralleled the level of activity of microsomal and mitochondrial marker enzymes found in the RSER preparation. Details of these experimental findings and some implications are discussed in view of the possible functional role of RSER.
Partial purification of a ribonucleic acid binding cAMP-independent protein kinase from embryonic chicken muscle
Authors: Hudson Alan P. , Bag Jnanankur , Sells Bruce H.
Published: December 2009

A cAMP-independent protein kinase (P38 kinase) from embryonic chicken muscle with ability to phosphorylate a 38 000 molecular weight polypeptide and to bind to RNAs has been further characterized. An approximately 2000-fold purification of this enzyme was achieved by a combination of affinity and ion-exchange chromatography. Our studies indicate that this protein kinase can not phosphorylate the small subunit of rabbit reticulocyte initiation factor eIF-2 in the presence of its normal endogenous substrate, nor is it activated over a wide range of concentrations of double-stranded RNA. This P38 kinase is, therefore, distinct from the hemin-regulated translational inhibitor of protein synthesis in rabbit reticulocytes and from the interferon-induced protein kinase identified in several systems.
Changes in the heterogeneity of ribulosebisphosphate carboxylase–oxygenase in winter rye induced by cold hardening
Authors: Huner N. P. A. , Hayden D. B.
Published: December 2009

The quaternary structures of ribulose-1, 5-bisphosphate carboxylase–oxygenase from cold-hardened and unhardened Puma rye were examined by two-dimensional gel electrophoresis according to the method of O'Farrell. The results indicate that major changes in charge heterogeneity occur in the large subunit of this enzyme during growth at cold-hardening temperatures. The extent of charge heterogeneity decreased upon adaptation of Puma rye to cold-hardening temperatures. In addition to charge heterogeneity, molecular weight heterogeneity was also evident in the large subunit polypeptides of the enzyme from cold-hardened and unhardened Puma rye.
Novel aspects of the structure of the Escherichia coli nucleoid investigated by a rapid sedimentation assay
Authors: Lee Jeremy S. , Morgan A. Richard
Published: December 2009

The Escherichia coli nucleoid is maintained in its folded highly condensed state by constraints which involve RNA and protein. We have developed a rapid sedimentation assay to determine the state of folding of the membrane-free nucleoid. An approximate measure of the stability of the nucleoids under various conditions can then be estimated by measuring the temperature at which the nucleoids unfold. Using ethidium and gamma irradiation (which removes the negative supercoiling of the native nucleoid) as probes, it can be shown that there are two types of constraint involved in the condensation of the nucleoid. One of these constraints is destablized by ethidium but stabilized by negative supercoiling; the second constraint is unaffected by both ethidium and negative supercoiling. Several models can be proposed: (i) a DNA∙RNA duplex, (ii) a double-strand DNA (dsDNA)∙RNA triplex, (iii) DNA-protein interactions, (iv) a topological knot with RNA, and (v) a DNA tetraplex. The topological knot model is not consistent with the data and many combinations of the others can be excluded. If RNA is involved in both constraints then RNA∙DNA duplexes and dsDNA∙RNA triplexes are involved in stabilizing the nucleoid.
An improved double antibody radioimmunoassay for the determination of insulin in serum, plasma, and tissue incubation media
Authors: Dalpé-Scott Marthe , Heick H. M. C. , Bégin-Heick Nicole
Published: December 2009

We have modified the double antibody method of insulin radioimmunoassay to allow relatively short incubation periods and the use of centrifugation to separate bound from free insulin. This was achieved by altering the order of addition of reagents and by adding normal guinea-pig serum to reduce nonspecific interactions. The method allows for precise measurements in the range of 0–3.2 ng insulin. Both serum and plasma give consistent values. The technique is useful for the measurement of insulin levels in samples of limited size such as those from small experimental animals.
The effect of lidocaine on cholesterol influx, esterification, and accumulation in cultured cells
Authors: Bell Frank P. , Rothblat G. H. , Bamberger M.
Published: December 2009

Lidocaine, a local anesthetic, inhibited cholesterol esterification in various cultured cells derived from tissues of the mouse, rat, hamster, monkey, and man. Esterification of exogenous [1-14C]oleate, fatty acid synthesized in situ from [1-14C]acetate, and exogenous [7-3H]cholesterol was reduced 20–50% with 1.5 mM lidocaine in the culture medium. In Fu5AH rat hepatoma cells, incubated for 24 h with hyperlipemic serum lipoproteins and increasing levels of lidocaine up to 1.5 mM, unesterified (free) cholesterol mass of the cells increased about 25% whereas the cholesteryl ester mass fell about 40%. The net result was a reduction in total cellular sterol. When the cells were incubated with lidocaine and hyperlipemic serum lipoproteins labeled with [7-3H(N)]cholesterol of known specific activity, incorporation of exogenous free cholesterol into cellular free cholesterol was constant, whereas there was a dose-dependent reduction in the amount of exogenous cholesterol appearing in cholesteryl esters. Additionally, a comparison of specific activities of cellular free cholesterol and cholesteryl esters at intervals over a 24-h period suggests that lidocaine also inhibits lysosomal cholesterol ester hydrolase (EC 3.1.1.13) in the Fu5AH cell line.
Soluble neutral maltase–glucoamylase from the small intestine: separation and characterization of components with differing affinity for concanavalin A
Authors: Forstner G. , Salvatore A. , Lee L. , Forstner J.
Published: December 2009

Intestinal maltase with a neutral pH optimum exists in both a brush border membrane-bound form and a soluble form in suckling rat intestine. Previous experiments in our laboratory have shown that the soluble enzyme contains a component which binds much more tightly to concanavalin A (ConA) than solubilized forms of the membrane enzyme. We studied the origin of this component by subjecting neutral, soluble maltase activity to chromatography on Sepharose 4B at age 13, 18 (preweaning), and 25 (postweaning) days. At 13 days, two maltase peaks were obtained with approximate molecular weights of 400 000 (peak I) and 150 000 (peak II). Peak II was less prominent at 18 days and was absent at 25 days. At 13 days, the majority of peak I consisted of material which was bound between 0.025 and 0.05 M α-methyl mannoside on gradient elution chromatography of ConA-Sepharose. Peak II contained material which eluted between 0.075 and 0.3 M α-methyl mannoside. At 25 days, all of the soluble maltase eluted between 0.025 and 0.04 M α-methyl mannoside. Peak I and peak II maltases had similar pH optima and Km's for maltase. Peak II maltase had a fourfold greater activity toward glycogen than peak I maltase with approximately the same activity for palatinose, turanose, and trehalose. Both maltases were precipitated by an antibody raised against adult membrane-bound maltase. Soluble maltase with neutral pH activity in the suckling rat intestine, therefore, consists of two immunologically related isozymes which differ in their molecular weight, their binding by ConA, and their specificity for glycogen. The small isozyme disappears at or about the time of weaning.
Tryptic peptide analysis of the human apolipoprotein E isomorphs
Authors: Pereira Leo V. , Dolphin Peter J.
Published: December 2009

The nature of the polypeptide backbone of human apolipoprotein (apo) E present in the very low density lipoproteins (VLDL) of normal and homozygous type III hyperlipoproteinemic patients was investigated by tryptic cleavage fingerprinting and specific chemical modification studies. Apo E from normal subjects was resolved on polyacrylamide isoelectric focussing gels into five bands (apo E-I′, E-I, E-II, E-III, and E-IV), whereas apo E from type III patients was resolved into three bands (apo E-I3′, E-I3, and E-II3). The apo E isoforms, contained within unstained polyacrylamide gel slices, were washed to remove ampholytes, desialylated, and digested with L-1-tosylamido-2-phenylethylchloromethyl ketone treated trypsin. Autoradiography of 125I-labelled tryptic apo E peptides showed complete identity between all isoforms from normal subjects. High performance liquid chromatographic (HPLC) analysis showed that complete peptide identity exists between apo E-I′, E-I, and E-II and between apo E-I3′, E-I3, and E-II3. Distinct HPLC peptide profiles were found for apo E-II, E-III, E-IV, and E-II3. These resolved peak differences were reproducible between runs, between digests, and between apo E isolations, suggesting that the distinct profiles were neither a result of artifacts nor of contamination. Specific chemical modification studies revealed that human apo E isomorphism is due, in part, to differences in arginine and cysteine residues but not to lysine residues. These findings indicate that human apo E isomorphism results from differences in the primary amino acid sequence of the individual isoforms in addition to charged carbohydrate heterogeneity. Furthermore, the apo E isomorphic profile observed in homozygous type III hyperlipoproteinemic patients reflects both a deficiency of apo E-III and E-IV and the presence of the altered apo E-II isoprotein (apoE-II3).
A rapid and quantitative high performance liquid chromatographic method for assaying bilirubin and its conjugates in bile
Authors: Gordon Ellen R. , Goresky Carl A.
Published: December 2009

A rapid and quantitative high performance liquid chromatographic method for assaying bilirubin and its conjugates in bile has been developed. It is based on the use of ion-pair reverse-phase chromatography, utilizing heptanesulfonic acid in an acetate buffer, with a progressively increasing gradient of acetonitrile. The method resolves the following bilirubin IXα conjugates from bile: bilirubin diglucuronide, the two isomeric forms of bilirubin monoglucoside monoglucuronide diester, the two isomeric forms of bilirubin monoglucuronide, and bilirubin diglucoside. Unconjugated bilirubin is then eluted from the column by increasing the flow rate. The method also resolves the bilirubin XIIIα and IIIα isomers of both bilirubin and the conjugates. In each case, the bilirubin XIIIα precedes and the bilirubin IIIα follows the bilirubin IXα component. The high performance chromatographic run is completed in 35 min. The identity of the conjugates was ascertained by use of reference compounds isolated by thin-layer chromatography and by recollection of chromatographic peaks with identification of their diazo derivatives. The method was shown to have sufficient sensitivity that in vitro conjugating systems can be explored. Recollection and reinjection indicated that no isomeric scrambling occurs during the analytical procedure.
Effect of ACTH or zinc treatment on plasma aldosterone and corticosterone levels and on the in vitro steroid output from adrenocortical cells
Authors: Payet Nicole , Lehoux Jean-Guy
Published: December 2009

We have studied the effect of in vivo treatment with two forms of ACTH (Synacthen and Duracton) and of zinc hydroxide on plasma corticosteroid levels from adult Long Evans female rats. The corticosteroid output by isolated zona glomerulosa cells in vitro was also studied. Dose–response experiments showed that, after 2 days of treatment, Synacthen caused a 2.5- and 25.9-fold increase in plasma aldosterone and corticosterone levels, respectively, while maximal increases of 1.7- and 5.6-fold were obtained following treatment with Duracton. In contrast to elevated plasma steroid levels, the basal aldosterone and corticosterone output by isolated zona glomerulosa cells was significantly decreased for all doses of Synacthen administered. The 8 IU/day treatment with Synacthen produced an 86% diminution of aldosterone output while a treatment of 32 IU/day with Duracton gave only a 48.8% decrease. Concomitantly the Synacthen treatment provoked a high mitotic response in the zona glomerulosa cells (fivefold over control). A 2-week treatment with Synacthen resulted in elevated plasma aldosterone and corticosterone levels and produced a 92% diminution of aldosterone output by isolated zona glomerulosa cells. The aldosterone and corticosterone output from these cells was not enhanced by the addition of ACTH in the incubation media; zona glomerulosa cells of animals treated with Synacthen were no longer responsive to ACTH stimulation in vitro. The effect of a 2-day treatment with zinc hydroxide on plasma aldosterone and corticosterone levels and on steroid output by isolated adrenocortical cells was different from that of Synacthen. This meant that zinc was not the active principle of the Synacthen preparation. Our results indicate that long-term treatment with ACTH provokes profound functional changes at the adrenocortical zona glomerulosa level.
Structure of the glycopeptides of a human γ1-immunoglobulin G (Tem) myeloma protein as determined by 360-megahertz nuclear magnetic resonance spectroscopy
Authors: Grey A. A. , Narasimhan S. , Brisson J.-R. , Schachter H. , Carver J. P.
Published: December 2009

High field magnetic resonance spectroscopy has been utilized to deduce the primary structure of the glycopeptides from a human myeloma γ1-immunoglobulin G (Tem). The major structures found belong to the biantennary complex class of glycopeptides, with a minor (5%) fraction belonging to the bisected biantennary complex class. In the biantennary class, three structures were present with different residues at the termini of the αMan(1-6) and αMan(1-3) arms: (i) with βGal(1-4) and αNeuNAc(2-6), respectively (33%); (ii) with βGal(1-4) and βGal(1-4), respectively (45%); and (iii) βGal(1-4) and βGlcNAc(1-2), respectively (17%). In the bisected biantennary class only the latter termini were found for the two arms. These results suggest that the galactosyl transferase in these cells has a preference for the βGlcNAc(1-2) of the αMan(1-6) arm and that the sialyltransferase has a preference for the βGal(1-4) of the αMan(1-3) arm.
Purification and characterization of dihydrofolate reductase from Walker 256 carcinosarcoma
Authors: Johnson Susan J. , Gupta Sagar V. , Stevenson Kenneth J. , Freisheim James H.
Published: December 2009

Dihydrofolate reductase of Walker 256 carcinosarcoma has been purified to homogeneity by affinity chromatography. The enzyme reduced 28 μmol dihydrofolate (FAH2)∙min−1∙mg protein−1 at 22 °C and pH 7.3. Km values with respect to FAH2 and NADPH were 21 and 29 mM, respectively. The IC50 (amount of inhibitor required for 50% loss of enzyme activity) values were 0.2 nM for MTX and aminopterin and 50 and 67 nM, respectively, for N10-formyl FA and triazinate (NSC-139105). The pH maximum is around pH 7.0 and the isoelectric point is 6.8. This reductase has an apparent molecular weight of 21 500. The N-terminal amino acid is valine and the comparison of the N-terminal 20 residues of this reductase shows very high sequence homology with other mammalian reductases. The enzyme contains two cysteine residues and one of these residues is not involved in catalysis. This reductase has four tryptophan residues and modification of one of these residues leads to loss of activity. The intrinsic circular dichroic (CD) spectrum of this reductase is very different from the CD spectra of reductase of Escherichia coli B and L1210/MTX. However, the CD spectra of the enzyme–substrate and enzyme–inhibitor complexes are very similar to that of the L1210/MTX enzyme. This suggests that the ligands may be constrained in similar conformation on the two enzymes. The fluorescence emission maximum at 314 nM when activated at 286 nM is considerably lower than other mammalian enzymes.
Hydration of acetone in the gas phase and in water solvent
Authors: Yang Kiyull , Hsieh Yih-Huang , Kim Chan-Kyung , Zhang Hui , Wolfe Saul
Published: December 2009

In water solvent, the hydration of acetone proceeds by a cyclic (cooperative) process in which concurrent C–O bond formation and proton transfer to oxygen take place through a solvent and (or) catalyst bridge. Reactivity is determined primarily by the concentration of a reactant complex and not the barrier from this complex. This situation is reversed in the gas phase; although the concentrations of reactive complexes are much higher than in solution, the barriers are also higher and dominant in determining reactivity. Calculations of isotope effects suggest that multiple hydron transfers are synchronous in the gas phase to avoid zwitterionic transition states. In solution, such transition states are stabilized by solvation and hydron transfers can be asynchronous.
Highly stereoselective facile synthesis of β-amino carbonyl compounds via a Mannich-type reaction catalyzed by γ-Al2O3/MeSO3H (alumina/methanesulfonic acid: AMA) as a recyclable, efficient, and versatile heterogeneous catalyst
Authors: Sharghi Hashem , Jokar Mahboubeh
Published: December 2009

Mannich reaction of ketones, aromatic aldehydes, and aromatic amines catalyzed efficiently by γ-Al2O3/MeSO3H (alumina/methanesulfonic acid: AMA) as a heterogeneous catalyst, which were carried out in EtOH at ambient temperature to afford the corresponding β-amino ketones in good yields and high stereoselectivities in favor of the anti isomer, was described for the first time. It was found that this catalyst could be completely recovered and reused without loss of its catalytic activities and is thus environmentally conscious. Furthermore, the use of γ-Al2O3/CH3SO3H (AMA) catalyst is feasible because of its easy preparation, easy handling, stability, easy recovery, reusability, good activity, stereoselectivity, and eco-friendliness. The use of this method provides a novel and improved modification of the three-component Mannich reaction in terms of mild reaction conditions and clean reaction profiles, using a very small quantity of catalyst and a simple workup procedure.
Synthesis and electrochemical behavior of triazole-containing nicotinamide adenine dinucleotide analogs
Authors: Liu Wujun , Hou Shuhua , Zhao Zongbao Kent
Published: December 2009

The coupling of 2′,3′-di-O-acetyl nicotinamide mononucleotide with 3-butyn-1-ol in the presence of 2,4,6-triisopropylbenzenesulfonyl chloride quantitatively afforded a terminal alkyne-containing intermediate. Furthermore, copper(I)-mediated Huisgen [3 + 2] cycloaddition with a series of azido compounds in a two-phase solvent system gave eight triazole-containing nicotinamide adenine dinucleotide analogs with yields over 88%. The cyclic voltammetric behaviors of these novel analogs were investigated with a glassy carbon electrode, and structural features of these analogs on their electrochemical properties were briefly discussed.
Ionophilic phosphonium-appended carbopalladacycle catalyst for Suzuki–Miyaura and Heck cross-coupling catalysis
Authors: Tindale Jocelyn J. , Ragogna Paul J.
Published: December 2009

An ionic liquid, covalently tethered to an efficient transition-metal catalyst in the presence of an ionic liquid reaction medium, can utilize ionophilic interactions to improve catalyst activity, recyclability, and product isolation while decreasing catalyst leaching. Given the greater stability of phosphonium salts in comparison to imidazolium ionic liquids under basic conditions, phosphonium-tagged oxime carbopalladacycle salts were prepared and employed in both Heck and Suzuki–Miyaura reactions. The desired product was obtained in good yields for up to four catalyst cycles in the case of the Suzuki–Miyaura reaction. While taking advantage of the non-volatile nature of ionic liquids, the product was isolated through simple sublimation from the reaction mixture, eliminating issues associated with catalyst leaching, and the remaining ionic liquid solvent–catalyst mixture was ready for further catalysis.
On the microwave-assisted synthesis of acylphenothiazine derivatives — Experiment versus theory synergism
Authors: Gaina Luiza , Porumb Dan , Silaghi-Dumitrescu Ioan , Cristea Castelia , Silaghi-Dumitrescu Luminita
Published: December 2009

The microwave-assisted synthesis of a series of acylphenothiazine derivatives is described. 10H-Phenothiazine-3-carbaldehyde derivatives were obtained in moderate yields by the Duff formylation reaction, and 10-acetyl-phenothiazine derivatives were obtained in excellent yields by acetylating phenothiazine derivatives with acetic anhydride. A theoretical explanation for the chemoselectivity and regioselectivity of these acylation reactions applied to phenothiazine substrates was attempted by molecular-modeling analyses based on molecular mechanics, and semi-empirical and DFT calculations.
Modeling haul-out behavior of walruses in Bering Sea ice
Authors: Udevitz Mark S. , Jay Chadwick V. , Fischbach Anthony S. , Garlich-Miller Joel L.
Published: December 2009

Understanding haul-out behavior of ice-associated pinnipeds is essential for designing and interpreting population surveys and for assessing effects of potential changes in their ice environments. We used satellite-linked transmitters to obtain sequential information about location and haul-out state for Pacific walruses, Odobenus rosmarus divergens (Illiger, 1815), in the Bering Sea during April of 2004, 2005, and 2006. We used these data in a generalized mixed model of haul-out bout durations and a hierarchical Bayesian model of haul-out probabilities to assess factors related to walrus haul-out behavior, and provide the first predictive model of walrus haul-out behavior in sea ice habitat. Average haul-out bout duration was 9 h, but durations of haul-out bouts tended to increase with durations of preceding in-water bouts. On average, tagged walruses spent only about 17% of their time hauled out on sea ice. Probability of being hauled out decreased with wind speed, increased with temperature, and followed a diurnal cycle with the highest values in the evening. Our haul-out probability model can be used to estimate the proportion of the population that is unavailable for detection in spring surveys of Pacific walruses on sea ice.
Responding to spatial and temporal variations in predation risk: space use of a game species in a changing landscape of fear
Authors: Tolon V. , Dray S. , Loison A. , Zeileis A. , Fischer C. , Baubet E.
Published: December 2009

Predators generate a “landscape of fear” within which prey can minimize the risk of predation by selecting low-risk areas. Depending on the spatial structure of this “landscape”, i.e., whether it is coarse- or fine-grained, prey may respond to increased risk by shifting their home ranges or by fine-scale redistributions within these ranges, respectively. We studied how wild boar ( Sus scrofa L., 1758) responded to temporal changes in risk in hunted areas (risky habitat) surrounding a nature reserve (refuge habitat). Animals with home ranges “in contact” with the reserve during the low-risk season were the only ones to shift toward the refuge when the risk increased. These shifts occurred at two temporal scales in response to the increased risk during the daytime and during the hunting season. Whereas animals not influenced by the reserve found food and shelter in forest during the hunting season, shifts to the refuge area were detrimental to the rather scarce forest areas in the reserve. This confirms that spatiotemporal changes in risk are major drivers of animal distribution when predation strongly limits their fitness. Their response is, however, scale-dependent and reflects at the individual level the perceived structure of their “landscape of fear”.
Viviparity and embryonic adaptations in the teleost Clinus superciliosus
Authors: Veith W. J.
Published: December 2009

Autoradiographic studies reveal that embryos of Clinus superciliosus absorb nutrients from the embryotrophe secreted by the follicular wall. The embryonic structure active in nutrient absorption is the epidermis including that of the fins and the gut. Absorption initially takes place mainly through the epidermis, with the pericardial and yolk-sac areas being the most active. In prepartum embryos most of the nutrient absorption takes place through the gut. Embryonic exchange surfaces of C. superciliosus were studied by both light and scanning electron microscopy. Changes in absorptive activity during embryonic development were mirrored by changes in surface topography and intestinal anatomy. The relative surface area of early embryos is greatly increased by numerous epidermal macroridges, which are particularly abundant in the pericardial and yolk-sac areas, as well as by epidermal microvilli. With increase in embryo size, the macroridges are reduced in number, and finally disappear just prior to birth. However, the mid- and hind-gut areas hypertrophy during gestation. It is suggested that this hypertrophy compensates for the progressive reduction in epidermal surface area during development and that such reduction in surface area is a possible osmotic adaptation.
Structural alterations in embryos and alevins of the Atlantic salmon, Salmo salar L., induced by continuous or short-term exposure to acidic levels of pH
Authors: Daye P. G. , Garside E. T.
Published: December 2009

Embryos of the Atlantic salmon, Salmo salar L., were incubated continuously from fertilization, at pH 6.8 (control), 5.0, 4.5, 4.3, 4.0, and 3.7, at 5–6 °C. The subsequent alevins in these environments were maintained at these levels for 40 days after hatching. Generally, lethal and sublethal injuries were separable only as to degree and distribution. Sublethal alterations occurred in the integument, gill, blood, and blood vascular structures of all live alevins incubated at pH 5.0 and lower. At pH 4.5 and lower, injuries also occurred in brain, optic retina, kidney, and spleen. Some tissue regeneration occurred in the embryonal rudimentary integument at pH 4.5 and lower. Regeneration also occurred but to a lesser degree in pseudobranch, kidney, spleen, and erythrocytes. Injury of the integument was the apparent cause of death in prehatching embryos since it is the major site of respiration and ion exchange. As gills expand in posthatching alevins, they assume these functions and destruction of branchial epithelium then becomes the prime cause of death. The nature of cell injury and consequent dysgenesis at tissue and organ levels are not ascribable uniquely to acidic stress. Some injuries are similar to those caused variously by heavy metals, detergents, halogenated organic compounds, some petroleum fractions, and chronic and acute high temperature in postalevin stages of several species of fish.
Effect of social environment within the brood on dominance rank in gallinaceous birds (Tetraonidae and Phasianidae)
Authors: Boag D. A. , Alway J. H.
Published: December 2009

The effect of brood composition (number of siblings of the same sex) on the dominance status achieved by individual members of a brood, during postbrood interactions with conspecifics of the same sex, was investigated in red grouse and Japanese quail. In both species, the social environment provided by the brood appeared to influence the outcome of these interactions; the potential deviation of an individual's dominance rank from the mean was directly related to the number of broodmates of the same sex.
Crop filling and crop emptying by the stable fly Stomoxys calcitrans L.
Authors: Venkatesh K. , Morrison P. E.
Published: December 2009

In Stomoxys the immediate destination of sugar or blood is the midgut, and not the crop. The filling of the crop with blood appears to involve several factors, including age, ambient temperature, temperature of the blood meal, disturbance of the fly, and interrupted feedings. In all experiments the sex of the fly had no effect on crop filling. The age of the fly did not influence crop filling when flies fed by piercing the skin. The crop empties of blood in 10–15 min. Rate of crop emptying of sugar solutions depended upon the molarity of solutions consumed.
Studies on the parasites of Pacific herring (Clupea harengus pallasi Valenciennes): survey results
Authors: Arthur J. R. , Arai H. P.
Published: December 2009

The results of a survey of the parasite fauna of Pacific herring (Clupea harengus pallasi Valenciennes) conducted during the years 1975 to 1977 are presented. Thirty-two species (three Myxosporida, three Protozoa, two Monogenea, nine Digenea, three Cestoidea, six Nematoda, four Acanthocephala, and two Copepoda) are reported from examination of 175 juvenile and 594 adult herring collected from the waters off California, Oregon, Washington, British Columbia, and Alaska. Among those parasites for which specific identifications could be made are five species previously unreported from the genus Clupea (metacercariae of Prosorhynchoides basargini (Layman, 1930) and Galactosomum phalacrocoracis Yamaguti, 1939; plerocercoids of Nybelinia surmenicola Okada in Dollfus, 1929; juvenile Corynosoma villosum Van Cleave, 1953; and Rhadinorhynchus trachuri Harada, 1935) and three species not previously reported from North American waters (Ortholinea orientalis (Shulman and Shulman-Albova, 1953); Gyrodactyloides petruschewskii Bykhowsky, 1947; and Gyrodactylus harengi Malmberg, 1957).
The role of the "encounter" call in spacing of Pacific tree frogs, Hyla regilla
Authors: Whitney Carl L.
Published: December 2009

When calling male Pacific tree frogs come closer together than about 50 cm, they switch from the mating call to the encounter call. After an exchange of encounter calls, one of the frogs may submit by retreating or ceasing to call, or they may fight, after which the loser submits. To investigate the role of the encounter call in maintaining spacing, I compared the responses of calling males lo playback of encounter calls and mating calls. During 60-s playbacks, most frogs responded initially to both vocalizations by uttering encounter calls, but they were more likely to respond further to encounter calls by either attacking or submitting. I suggest that the encounter call serves to reduce the amount of time that calling frogs remain close together and, as a consequence, to enhance their chances of attracting females.
Anterior midgut proteinase inhibitor from Glossina morsitans morsitans Westwood (Diptera: Glossinidae) and its effects upon tsetse digestive enzymes
Authors: Houseman Jon G.
Published: December 2009

The anterior midgut of Glossina morsitans morsitans Westwood contains a proteinase inhibitor, molecular weight 5000 ± 2000daltons, stable to 1 M HCl, heat, and dialysis, but unstable to 1% trichloroacetic acid. Inhibitor activity is not associated with anticoagulant in the anterior midgut. The specific activity of the proteinase inhibitor is similar in mated and unmated females and greater than in male tsetse flies. Proteinase inhibitor inhibits proteinase VI and trypsin hydrolysis of N-benzoyl-L-arginine ethyl ester (BAEE) and benzoyl-DL-arginine-p-nitroanilide (BAPNA) but has no effect on proteinase VI hydrolysis of haemoglobin. Inhibition of trypsin hydrolysis of haemoglobin is noncompetitive. Proteinase inhibitor levels in the anterior midgut decreased immediately after feeding and then increased, reaching a maximum 60–100 h after ingestion of the bloodmeal. Postteneral flies contained higher levels of proteinase inhibitor than teneral individuals. Trypsin activity in gut homogenates of Phormia regina and Aedes aegypti was inhibited by the tsetse inhibitor. There was no detectable inhibition of bovine or Pterostichus adstrictus trypsin activity. Inhibition of Periplaneta americana trypsin occurred but was less than fly trypsin inhibition. The possible role of the inhibitor in terminating proteinase production is discussed.
Development of Diplotriaena tricuspis (Nematoda:Diplotriaenoidea), a parasite of Corvidae, in intermediate and definitive hosts
Authors: Cawthorn Richard J. , Anderson Roy C.
Published: December 2009

Development of Diplotriaena tricuspis (Fedtschenko, 1874) Henry and Ozoux, 1909, of the American crow Corvus brachyrhynchos Brehm, occurred in capsules in the fat body of the migratory grasshopper Melanoplus sanguinipes F. and the African desert locust Schistocerca gregaria L. At 30 °C the first moult began at 4 days and the second at 8 days after infection in late-instar nymphal and young adult insects. One unusual feature was the rapid growth of the oesophagus which compressed the intestine of the third-stage larva. Grasshoppers appeared to be more suitable intermediate hosts than locusts. In crows, larvae of D. tricuspis apparently underwent their early development in the hepatic portal system and moved via the posterior vena cava to the heart. The third moult began at 4 days and the fourth at 20 days after infection. Subadult nematodes were in the right heart 25 days after infection. Nematodes broke out of arteries within the lungs and moved to the air sacs as early as 30 days after infection. The prepatent period was approximately 4 months. Attempts to transmit D. tricuspis to various noncorvids were unsuccessful.
The cellular responses of migratory grasshoppers (Melanoplus sanguinipes F.) and African desert locusts (Schistocerca gregaria L.) to Diplotriaena tricuspis (Nematoda:Diplotriaenoidea)
Authors: Cawthorn Richard J.
Published: December 2009

Twelve hours after infection first-stage larvae of Diplotriaena tricuspis (Nematoda:Diplotriaenoidea) had hatched, penetrated the gut wall, and entered lobules of the fat body of grasshoppers (Melanoplus sanguinipes F.) and African locusts (Schistocerca gregaria L.). Capsule development was similar in grasshoppers and locusts. Capsules, which had fibrous walls and contained both normal and degenerating adipocytes, developed at least as early as 4 days after infection. Capsules were well developed when the third stage was reached. The fibrous wall probably resulted from conversion of adipocytes to fibrous tissue. Larvae apparently had a readily available source of food (adipocytes) and were protected from the haemocytic response of the insect by the capsule wall. Larvae were not destroyed by haemocytes or melanization. Few larvae developed free in the haemocoele.