bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of a Highly Conserved NH
2
-Terminal Domain of the Human Parainfluenza Virus Type 3 RNA Polymerase
Authors: Malur Achut G. , Choudhary Suresh K. , De Bishnu P. , Banerjee Amiya K.
Published: July 2002

The RNA polymerase complex of human parainfluenza virus type 3 (HPIV 3), a member of the family
Paramyxoviridae
, is composed of two virally encoded polypeptides: a multifunctional large protein (L, 255 kDa) and a phosphoprotein (P, 90 kDa). From extensive deduced amino acid sequence analyses of the cDNA clones of a number of L proteins of nonsegmented negative-strand RNA viruses, a cluster of high-homology sequence segments have been identified within the body of the L proteins. Here, we have focused on the NH
2
-terminal domain of HPIV 3 L protein that is also highly conserved. Following mutational analyses within this domain, we examined the ability of the mutant L proteins to (i) transcribe an HPIV 3 minireplicon, (ii) transcribe the viral RNA in vitro using the HPIV 3 nucleocapsid RNA template, and (iii) interact with HPIV 3 P protein. Our results demonstrate that the first 15 amino acids of the NH
2
-terminal domain spanning a highly conserved motif is directly involved in transcription of the genome RNA and in forming a functional complex with the P protein. Substitution of eight nonconserved amino acids within this domain by the corresponding Sendai virus L protein residues yielded mutants with variable transcriptional activities. However, one mutant in which all eight amino acids were replaced with the corresponding residues of Sendai virus L protein failed to both transcribe the minireplicon and interact with HPIV 3 P and the Sendai virus P protein. The possible functional significance of the NH
2
-terminal domain of paramyxovirus L protein is discussed.
In Vivo Egress of an Alphaherpesvirus from Axons
Authors: Tomishima Mark J. , Enquist Lynn W.
Published: July 2002

Many alphaherpesviruses establish a latent infection in the peripheral nervous systems of their hosts. This life cycle requires the virus to move long distances in axons toward the neuron's cell body during infection and away from the cell body during reactivation. While the events underlying entry of the virion into neurons during infection are understood in principle, no such consensus exists regarding viral egress from neurons after reactivation. In this study, we challenged two different models of viral egress from neurons by using pseudorabies virus (PRV) infection of the rat retina: does PRV egress solely from axon terminals, or can the virus egress from axon shafts as well as axon terminals? We took advantage of PRV gD mutants that are not infectious as extracellular particles but are capable of spreading by cell-cell contact. We observed that both wild-type virus and a PRV gD null mutant are capable of spreading from axons to closely apposed nonneuronal cells within the rat optic nerve after intravitreal infection. However, infection does not spread from these infected nonneuronal cells. We suggest that viral egress can occur sporadically along the length of infected axons and is not confined solely to axon terminals. Moreover, it is likely that extracellular particles are not involved in nonneuronal cell infections. Taking these together with previous data, we suggest a model of viral egress from neurons that unifies previous apparently contradictory data.
Ortho Effect in Dissociation of Benzoic Acids with Electron-Accceptor Substituents Using the AISE Theory; Relation to para Substitution and Solvent
Authors: Pytela Oldřich , Kulhánek Jiří
Published: July 2002

Potentiometric titration at 25 °C has been used to measure the dissociation constants of 2- and 4-substituted benzoic acids with electron-acceptor substituents in methanol, N,N-dimethylformamide, acetonitrile, and acetone. But for a few exceptions, no significant differences have been found between the dissociation constants measured and those given in literature. Using the measured pKa values, those of 3-substituted derivatives taken from literature (measured in the same solvents) and those of 3- and 4-substituted derivatives measured in water, the so far missing substituent constants σi of NO and CH3SO substituents have been determined by Alternative Interpretation of Substituent Effects (AISE). The previously published relationships and the σi constants have been used to calculate the σm and σp constants for the given substituents and compare them with literature. The agreement was the better, the more reliable the corresponding Hammett substituent constant was. Using a non-linear regression model, we have analysed the structure of matrix of pKa values of ten 2-X-benzoic acids (X is electron-acceptor substituent) measured in the given organic solvents and in water. It has been found that in non-aqueous solvents the conjugate base of benzoic acid is stabilised by intramolecular hydrogen bond if X is COOH and SO2NH2 or electrostatic force if X is CH3SO. On the other hand, in water the carboxylate group is out of the plane of the benzene ring due to interaction between the solvated reaction centre and substituent, this being the case with all the substituents except for X = CHO, CH3CO, NO, and CN. In all the solvents used, intramolecular ring closure takes place between the carboxylate group and substituent X = CH3CO, CHO, and NO, this phenomenon being the most important in water.
1,1-Vinylboration and 1,1-Ethylboration of Di(alkyn-1-yl)silanes: Synthesis of New Siloles
Authors: Wrackmeyer Bernd , Tok Oleg L. , Bhatti Moazzam H. , Ali Saqib
Published: July 2002

Triethylborane (1) or trivinylborane (2) reacts with di(alkyn-1-yl)methylsilanes, MeSiH(C≡C-R)2 3 [R = Bu (a), t-Bu (b), SiMe3 (c)], to give the novel chiral 1-silacyclopenta-2,4-dienes (siloles) 4a-4c or 5a-5c, respectively, by twofold 1,1-organoboration. Similarly, di(alkyn-1-yl)dimethylsilane Me2Si(C≡C-t-Bu)2 3d reacts with 2 to give the silole 5d. These are the first applications of 2 in 1,1-organoboration reactions. All products are characterized by multinuclear magnetic resonance (1H, 11B, 13C, 29Si NMR).
Spontaneous closure of an acquired ventricular septal defect
Authors: Williams R I , Ramsey M W
Published: July 2002

Ventricular septal defect (VSD) is a rare but serious complication of acute myocardial infarction requiring early surgical intervention. A patient with acquired VSD that spontaneously closed over three months is presented. The literature on spontaneous closure of acquired VSDs is also reviewed.
Fatal haemorrhagic pulmonary oedema and associated angioedema after the ingestion of rofecoxib
Authors: Kumar N P , Wild G , Ramasamy K A , Snape J
Published: July 2002

Angioedema is a recognised side effect of rofecoxib, a cyclo-oxygenase-2 (COX-2) inhibitor. But death resulting from a haemorrhagic pulmonary oedema after its ingestion has not been recorded. The case of a 60 year old man who died from haemorrhagic pulmonary oedema in the presence of angioedema after the ingestion of two doses of 12.5 mg of rofecoxib is reported.
David Samwell (1751–98): surgeon on the Discovery
Authors: Morris J S
Published: July 2002

David Samwell, born in North Wales, was surgeon on the Discovery during the third and last voyage of Captain James Cook. Samwell wrote a biography of Cook and was a distinguished poet. He also served on several more voyages, retiring from the sea aged 45.
Towards a molecular phylogeny for the lichen family Pannariaceae (Lecanorales, Ascomycota)
Authors: Ekman Stefan , Jørgensen Per Magnus
Published: July 2002

The phylogeny of the family Pannariaceae (Lecanorales, lichenized Ascomycota) was investigated using ITS15.8SITS2 nuclear ribosomal DNA sequences representing 21 species. Phylogenetic estimations were performed using parsimony and a Bayesian Markov chain Monte Carlo (MCMC) tree sampling procedure. Several phylogenetic null hypotheses were tested, also using MCMC. The results indicate that Pannariaceae, as currently treated, is polyphyletic and that Degelia sect. Amphiloma, Fuscopannaria subg. Micropannaria, and Moelleropsis s.str. do not belong in the family. The inclusion of Parmeliella in the Pannariaceae could not be rejected, although it falls outside the family in the optimal trees. Psoroma, Santessoniella, Protopannaria, Fuscopannaria subg. Fuscopannaria, Moelleropsis s.str., and Pannaria unequivocally belong to the family. The Pannaria sphinctrina group belongs in Pannaria despite its green-algal photobiont. Protopannaria pezizoides is not, as sometimes treated, a Pannaria, although a relationship with Psoroma could not be ruled out. In the optimal trees, Moelleropsis s.str. is nested inside Fuscopannaria subg. Fuscopannaria and Santessoniella inside Psoroma, but null hypotheses of their independence from these genera could not be rejected. Pannaria cannot be divided into two monophyletic subgenera, Pannaria and Chryopannaria. The photobiont has changed twice or three times and the ascus apex and hymenial amyloidity twice within the Pannariaceae.Key words: lichens, Pannariaceae, ITS, ribosomal DNA, phylogeny, MCMC.
Experimental management for Snake River springsummer chinook (Oncorhynchus tshawytscha): trade-offs between conservation and learning for a threatened species
Authors: Paulsen Charles M , Hinrichsen Richard A
Published: July 2002

Using Snake River springsummer chinook (Oncorhynchus tshawytscha) as an example, we explore trade-offs between conservation (restoring population abundance to self-sustaining levels) and learning (reliably estimating how management strategies affect productivity). The population has been studied extensively, especially since 1992, when the evolutionarily significant unit (ESU) was listed under the U.S. Endangered Species Act. Understanding both the conservation and learning dimensions is crucial in evaluating management actions. Using a Bayesian simulation model calibrated with 40+ years of spawnerrecruit estimates, we performed population viability analyses to examine the biological risks of an array of management strategies. We also performed power analyses to estimate the precision of estimates of the actions' effects. The results suggest that if one can take actions that increase productivity and manage those actions as experiments, one can simultaneously increase fish numbers and reduce the uncertainty about the effects of those actions. However, because more powerful experiments will utilize controls where no action is taken, an experimental approach may increase risks to the ESU when compared to a strategy that tries to maximize productivity as soon as possible.
Biomimetic reactions in organic synthesis: Semi-pinacol rearrangements of some spirocyclic epoxyalcohols derived from Juliá-Colonna asymmetric epoxidations
Authors: Hauer Bernhard , Bickley Jamie F , Massue Julien , Pena Paula CA , Roberts Stanley M , Skidmore John
Published: July 2002

Epoxy tert-alcohols have been prepared from (E)-enones in a two-step approach consisting of JuliáColonna asymmetric epoxidation followed by Grignard alkylation of the epoxyketone. On treatment with sub-stoichiometric amounts of Yb(OTf)3 these trans-epoxyalcohols underwent efficient stereoselective semi-pinacol rearrangement to afford anti-α-phenyl-β-hydroxy-ketones (aldols). Under the same conditions, spirocyclic epoxyalcohols derived from 1-tetralone and 1-benzosuberone undergo either ring contraction (via semi-pinacol rearrangement) or fragmentation. A mechanistic rationale is presented to explain the formation of the various products.Key words: JuliáColonna reaction, asymmetric epoxidation, epoxy tert-alcohols, semi-pinacol rearrangement.
Water content influences the selectivity of CALB-catalyzed kinetic resolution of phenoxymethyl-substituted secondary alcohols
Authors: Jacobsen Elisabeth Egholm , Anthonsen Thorleif
Published: July 2002

Derivatives of 1-phenoxy-2-alkanols were kinetically resolved by esterification with irreversible and reversible acyl donors using lipase B from Candida antarctica (Novozyme 435) as a catalyst. To optimize the relative rate of reaction (the E-value), esterifications in eight different solvents with different water activities were performed. For 3-bromo-1-phenoxy-2-propanol (1), the E-values in all the solvents were higher when the water activity was increased, while the E-values for 1-phenoxy-2-pentanol (2) and 3-chloro-1-phenoxy-2-propanol (3) decreased by increasing water activity. The water content of the various reaction media with the same water activity was determined. Solvents such as 1,4-dioxane, acetonitrile, and tetrahydrofuran contained much more water than hexane, carbon tetrachloride, cyclohexane, toluene, and benzene. At high-water activity, the high-water content of the former group of solvents resulted in termination of the reaction at low conversion. The reason seemed to be that the acyl donor and possibly also the produced esters were hydrolyzed. This was not the case when the esterification was performed in water-immiscible solvents with the same water activity.Key words: kinetic resolution, E-value, solvents, water activity, water content.
Sodium borohydride: A versatile reagent in the reductive N-monoalkylation of α-amino acids and α-amino methyl esters
Authors: Verardo Giancarlo , Geatti Paola , Pol Elena , Giumanini Angelo G
Published: July 2002

α-Amino acids and α-amino methyl esters are easily converted to their N-monoalkyl derivatives by a reductive condensation reaction using several carbonyl compounds in the presence of sodium borohydride. This reducing agent has shown a wide versatility with minor but essential procedural variations. The reaction allows the α-monodeuterium labeling of the new N-substituent by use of sodium borodeuteride.Key words: α-amino acid, α-amino methyl esters, sodium borohydride, reductive N-monoalkylation, carbonyl compounds.
On the temperature dependence of the primary yield and the product Gεmax of hydrated electrons in the low-LET radiolysis of liquid water
Authors: Meesungnoen Jintana , Jay-Gerin Jean-Paul , Filali-Mouhim Abdelali , Mankhetkorn Samlee
Published: July 2002

Monte-Carlo simulations are performed to calculate the temperature dependence of the primary hydrated electron yield (Geaq-) for liquid water irradiated by low linear-energy-transfer radiation (LET ~ 0.3 keV µm1) in the range 25325°C. Calculations are carried out by taking properly into account the effect of the time and temperature dependencies of the water dielectric constant on the electroncation geminate recombination. Our computed Geaq- values slightly increase with increasing temperature, in good agreement with experiment. The product Geaq- εmax(eaq-), estimated by using existing experimental data of the maximum molar extinction coefficient εmax(eaq-), remains nearly constant or slightly increases, depending on the temperature dependence chosen for εmax. Our Geaq-εmax(eaq-) values compare generally well with most experimental data, as well as with the predictions of deterministic diffusion-kinetic model calculations. Moreover, our results indicate that the static dielectric constant of water (εs) does not play any significant role on the electroncation recombination at early times. Such a finding is inconsistent with the interpretation, proposed by certain authors in the literature, that Geaq- should in fact decrease as temperature is increased because of an increased electroncation geminate recombination due to a lowering of εs. Finally, the temperature dependence of the hydrated electron yields, calculated at various times between 10 ps and 1 µs, shows that at low LET, the time required to establish homogeneous chemistry in the bulk of the solution is ~106 s in the range ~25100°C, and that this time diminishes to ~107 s at higher temperatures. Key words: liquid water, radiolysis, temperature, hydrated electron (eaq-), radiolytic yields, electroncation geminate recombination, dielectric constant, molar extinction coefficient of eaq-, homogenization time.
Formation of single diastereomers of β-hydroxy sulfoxides by biotransformation of β-ketosulfides using Helminthosporium species NRRL 4671
Authors: Holland Herbert L , Ihasz Nancy , Lounsbery Brendan J
Published: July 2002

Single biotransformations of 1-(phenylthio)-2-propanone and 1-(p-methoxyphenylthio)-2-propanone by the fungus Helminthosporium species NRRL 4671 resulted in both sulfur oxidation to the sulfoxide and carbonyl reduction to the alcohol. The corresponding (SS,SC)-1-sulfinyl-2-propanols were obtained as single diastereomers following simple crystallization.Key words: biocatalysis, biotransformation, carbonyl reduction, Helminthosporium sp. NRRL 4671, sulfoxidation.
Bakers yeast-catalyzed synthesis of optically pure 4-tert-butyl-3-hydroxy beta-lactam cis-(3R,4S) and trans-(3R,4R) diastereomers
Authors: Kayser Margaret M , Yang Yan , Mihovilovic Marko D , Feicht Anton , Rochon Fernande D
Published: July 2002

Baker's yeast (Saccharomyces cerevisiae) reductions were applied to the synthesis of the paclitaxel C-13 side-chain analogue. An easily synthesized alpha-keto-beta-lactam (1-(4-methoxyphenyl)-4-tert-butylazetidin-2,3-dione, 4) was reduced by yeast cells to give a mixture of enantiomerically pure cis and trans isomers. Both compounds were isolated and characterized, and their absolute configurations were confirmed by X-ray crystallographic analysis.Key words: Taxol®, C-13 side-chain, paclitaxel analogues, optically pure alpha-hydroxy-beta-lactams, baker's yeast-catalyzed reductions.
X-ray diffraction, Raman spectroscopic, and solid-state NMR studies of the group 14 metal-(tetracarbonyl)cobalt complexes Ph3MCo(CO)4(M = Si, Sn, Pb)
Authors: Geller J M , Wosnick J H , Butler I S , Gilson D FR , Morin F G , Bélanger-Gariépy F
Published: July 2002

Single-crystal X-ray diffraction studies illustrate that the three title compounds are isomorphous, belonging to the triclinic space group P[Formula: see text], with slightly distorted trigonal bipyramidal geometry about cobalt. The solid-state29Si,119Sn, and207Pb cross-polarization magic angle spinning (CP MAS) NMR spectra are presented. The indirect spinspin coupling constant (J), quadrupolardipolar shift (d), direct dipolar coupling constant (D' ), anisotropy in spinspin coupling (ΔJ), and the chemical shift tensor were extracted. A plot of the reduced coupling constant vs. s-electron densities at the nucleus indicates that the Fermi contact term may be dominant for the tin and lead complexes; however, the large ΔJ for all complexes indicate that there are also significant anisotropic terms. Trends in the Raman scattering spectra are also discussed.Key words:29Si,119Sn, and207Pb CP MAS NMR, tetracarbonyl cobalt, spinspin coupling, chemical shift tensor, quadrupole coupling, Fermi contact, cobaltgroup 14.
Ab initio and DFT conformational analysis of selected flavones: 5,7-dihydroxyflavone (chrysin) and 7,8-dihydroxyflavone
Authors: Lau Ken S , Mantas Athena , Chass Gregory A , Ferretti Fernando H , Estrada Mario , Zamarbide Graziela , Csizmadia Imre G
Published: July 2002

Ab initio and DFT conformational analysis was performed on the flavone derivatives chrysin (5,7-dihydroxyflavone; 2-phenyl-5,7-dihydroxy-4H-1-benzopyran-4-one) and 7,8-dihydroxyflavone (2-phenyl-7,8-dihydroxy-4H-1-benzopyran-4-one). The structural features required for optimal stabilization in each molecule were identified. It was discovered that sparsely placed hydroxyl groups, particularly with hydrogen bond-like interactions, resulted in lowering the potential energy minimum for the molecules. It was also noted that one of the factors capable of destroying co-planarity was steric interference between closely placed functional groups across the phenyl and the benzo-γ-pyrane ring. Studies performed on the radical forms of the flavonoids, however, showed that the unpaired electron is confined only to the benzo-γ-pyrane ring, and not delocalized across the phenyl ring.Key words: flavonoid, flavone, chrysin, ab initio conformational analysis, anti-oxidant, free radical, 5,7-dihydroxy flavone, 7,8-dihydroxyflavone.
Interrelationships among northern flying squirrels, truffles, and microhabitat structure in Sierra Nevada old-growth habitat
Authors: Pyare Sanjay , Longland William S
Published: July 2002

During 1997-1998, we investigated the influence of both the relative abundance of truffles, preferred food items, and microhabitat structure on the occurrence of northern flying squirrels (Glaucomys sabrinus Shaw) in old-growth forest habitat of the Sierra Nevada Range, U.S.A. Following live-trapping sessions, we searched the forest floor for truffle diggings and sampled the soil for truffles. Diggings were more abundant where flying squirrels were captured, suggesting squirrels were active near areas of the forest floor where truffles had recently been excavated. The frequency of sampling plots with truffles was higher where squirrels were captured, further suggesting preferences for microhabitats where truffles were more abundant. We also measured 15 microhabitat variables at trap stations to evaluate the influence of aboveground microhabitat characteristics on squirrel occurrence. Results indicated that flying squirrels preferred microhabitats with understory cover, which may minimize predation from aerial predators like spotted owls (Strix occidentalis Merriam). Neither abundance of coarse woody debris, a feature conducive to fungal growth, nor the abundance of potential nesting sites (i.e., snags) measurably influenced squirrel occurrence. While various aboveground forest-microhabitat characteristics affect the use of old-growth forests by flying squirrels, these animals refine their use of these forests based on fine-scale changes in the availability of a highly preferred and ephemeral food item.
Monitoring male reproductive success in a Japanese black pine clonal seed orchard with RAPD markers
Authors: Goto S , Miyahara F , Ide Y
Published: July 2002

Overall male reproductive success was investigated in a Japanese black pine (Pinus thunbergii Parl.) clonal seed orchard consisting of 16 nematode-resistant clones, using random amplified polymorphic DNA (RAPD) markers. We genotyped all 16 of the orchard clones at selected RAPD loci by analyzing diploid needles and 10 haploid megagametophytes from each of them. In addition, the male parent of open-pollinated seedlings was identified by comparing their phenotypes with the genotypes of the orchard clones. In this way the male parents of 559 seedlings of 648 seedlings of progenies from 14 parental (orchard) clones were determined. The level of external pollen contamination in the seed orchard was estimated to be 2.2% for the total population. The effective mean selfing rate observed was 1.5%. Male reproductive success among clones varied widely, from 0.8 to 24.4%, for the total population. Our data suggest that the significant deviation in male reproductive success of individual clones from panmictic ratios may be a problem for the genetic quality in seed orchard crops. To improve the parental balance of seed orchard crops, the use of artificial management techniques such as gibberellin A4/7 treatment, supplemental mass pollination, and rearrangement of clonal ramets is recommended in seed orchards.
Interaction of a non-peptide agonist with angiotensin II AT1receptor mutants
Authors: Costa-Neto Claudio M , Miyakawa Ayumi A , Pesquero João B , Oliveira Laerte , Hjorth Siv A , Schwartz Thue W , Paiva Antonio CM
Published: July 2002

To identify residues of the rat AT1Aangiotensin II receptor involved with signal transduction and binding of the non-peptide agonist L-162,313 (5,7-dimethyl-2-ethyl-3-[[4-[2(n-butyloxycarbonylsulfonamido)-5-isobutyl-3-thienyl]phenyl]methyl]imidazol[4,5,6]-pyridine) we have performed ligand binding and inositol phosphate turnover assays in COS-7 cells transiently transfected with the wild-type and mutant forms of the receptor. Mutant receptors bore modifications in the extracellular region: T88H, Y92H, G196I, G196W, and D278E. Compound L-162,313 displaced [125I]-Sar1,Leu8-AngII from the mutants G196I and G196W with IC50values similar to that of the wild-type. The affinity was, however, slightly affected by the D278E mutation and more significantly by the T88H and Y92H mutations. In inositol phosphate turnover assays, the ability of L-162,313 to trigger the activation cascade was compared with that of angiotensin II. These assays showed that the G196W mutant reached a relative maximum activation exceeding that of the wild-type receptor; the efficacy was slightly reduced in the G196I mutant and further reduced in the T88H, Y92H, and D278E mutants. Our data suggest that residues of the extracellular domain of the AT1receptor are involved in the binding of the non-peptide ligand, or in a general receptor activation phenomenon that involves conformational modifications for a preferential binding of agonists or antagonists. Key words: angiotensin, receptor, GPCR, non-peptide agonist, transduction.
Angiotensin II is bound to both receptors AT1and AT2, parallel to the transmembrane domains and in an extended form
Authors: Deraët M , Rihakova L , Boucard A , Pérodin J , Sauvé S , Mathieu A P , Guillemette G , Leduc R , Lavigne P , Escher E
Published: July 2002

We have applied photoaffinity labelling methods combined with site-directed mutagenesis towards the two principal angiotensin II (AngII) receptors AT1and AT2in order to determine contact points between AngII and the two receptors. We have first identified the receptor contact points between an N- and a C-terminal residue of the AngII molecule and the AT1receptor and constructed with this stereochemical restriction a molecular model of AT1. A similar approach with a modified procedure of photoaffinity labelling has allowed us now to determine contact points also in the AT2receptor. Molecular modelling of AT2on the rhodopsin scaffold and energy minimisation of AngII binding into this AT2model produced a model strikingly similar to the AT1structure. Superposition of the experimentally obtained contact points of AngII with AT2upon this model revealed excellent congruence between the experimental and modelling results. Conclusions: (i) athough AT1and AT2have quite low sequence homology, they both bind AngII with similar affinity and in an almost identical fashion, as if the ligand dictates the way it has to be bound, and (ii) in its bound form, AngII adopts an extended conformation in both AT1and AT2, contrary to all previous predictions.Key words: angiotensin receptors, photolabelling method, contact points, molecular modelling.
Differentiation-dependent expression of cathepsin D and importance of lysosomal proteolysis in the degradation of UCP1 in brown adipocytes
Authors: Moazed Banafsheh , Desautels M
Published: July 2002

The lysosomal protease cathepsin D increased markedly in brown adipocytes during differentiation in primary cultures. Differentiated cells had 20 times the amount of immunoreactive cathepsin D found in preadipocytes. Cathepsin D mRNA, as estimated by relative RT-PCR, was also present in higher amounts in differentiated brown fat cells. Cathepsin D expression was not influenced by repeated exposures of brown adipocytes to norepinephrine (NE). Cathepsin D levels were also unchanged when NE was withdrawn for 48 h after cells had been exposed to NE for 7 days. In contrast, exposure of the cells to NE for 7 days increased their UCP1 content by more than twofold, which returned to basal levels within 48 h of withholding NE. The half-life of UCP1 under basal conditions and in cells chronically exposed to NE was estimated from reductions in [35S]methionine-labelled immunoprecipitable UCP1 over 72 h. UCP1 t1/2under basal conditions was 3.7 ± 0.4 days, which was similar to the half-lives of labelled mitochondrial translation products (3.6 ± 0.8 days). The turnover rates of both UCP1 and mitochondrial translation products were reduced by NE. The turnover rate of UCP1 in the presence or absence of NE cannot account solely for the rapid loss of UCP1 from brown adipocytes upon withdrawal of NE. This loss was reduced when cells were incubated with inhibitors of phosphatidylinositol 3-kinases (PI 3-kinase), previously shown to block formation of autophagic vacuoles. Thus, brown adipocytes acquire a large capacity for both uncoupled metabolism and for lysosomal proteolysis during differentiation. Withdrawal of NE, as often occurs in vivo from suppression of sympathetic nervous system activity, would not only terminate thermogenesis but also favor formation of autophagic vacuoles to rapidly reduce the cell content of UCP1-containing mitochondria.Key words: brown fat, autophagy, protein degradation, protein turnover, phosphatidylinositol 3-kinase, wortmannin, LY294002, 3-methyladenine.
Control of proteolysis by norepinephrine and insulin in brown adipocytes: role of ATP, phosphatidylinositol 3-kinase, and p70 S6K
Authors: Moazed Bita , Desautels M
Published: July 2002

The objective of this study was to evaluate some of the mechanisms by which norepinephrine (NE) and insulin may influence protein degradation in mouse brown adipocytes differentiated in cultures. The effects of NE and insulin, alone or in combination, on three factors known to influence proteolysis (maintenance of cell ATP and 1-phosphatidylinositol 3-kinase (PI 3-kinase) and p70 ribosomal S6-kinase (p70 S6K) activities) were examined. It was proposed that NE affects proteolysis indirectly by decreasing cell ATP from activation of uncoupling protein-1 (UCP1)-dependent mitochondrial respiration. This was tested by comparing the effects of NE and fatty acids (which directly activate UCP1) on proteolysis in brown adipocytes, as well as in pre-adipocytes and 3T3-L1 adipocytes, which do not express UCP1. An inhibitory effect of insulin on proteolysis is observed in both pre-adipocytes and differentiated cells, whereas NE and exogenously added fatty acids inhibit proteolysis only in brown adipocytes. There is a linear relationship between reductions in cell ATP and proteolysis in response to increasing concentrations of NE or fatty acids. PI 3-kinase activity is required for proteolysis, because two selective inhibitors (wortmannin and LY294002) reduce proteolysis in both pre-adipocytes and differentiated cells. This effect is not additive to that of NE, which suggests they affect the same proteolytic pathway. In contrast to NE, insulin increases PI 3-kinase activity and phosphorylation of p70 S6K. Rapamycin, which prevented insulin-dependent increase in phosphorylation of p70 S6K, increases proteolysis in brown adipocytes and antagonizes the inhibitory effect of insulin on proteolysis, but not the inhibitory effect of NE. Thus, insulin inhibits proteolysis via rapamycin-sensitive activation of p70 S6K, whereas the effect of NE appears largely to be a function of decreasing cell ATP content.Key words: brown fat, 3T3-L1 adipocytes, protein degradation, ATP, uncoupling protein-1, fatty acids, rapamycin, wortmannin, LY294002.
Reevaluation of patterns of mussel (Mytilus edulis) selection by European Oystercatchers (Haematopus ostralegus)
Authors: Nagarajan R , Lea S E.G , Goss-Custard J D
Published: July 2002

European Oystercatchers (Haematopus ostralegus) were highly selective towards mussels between 35 and 50 mm in length, and fewer than 5% of mussels taken were below 35 mm or above 50 mm. The oystercatchers selected ventrally thin-shelled mussels, especially if the length was more than 35 mm, regardless of whether they opened the right or left valve of the mussel. The oystercatchers also took mussels that had few barnacles on the ventral surface. Although brown-shelled mussels were rare in the population, oystercatchers showed a strong preference for them. Generally, oystercatchers consumed ventrally flat mussels, especially in the smaller length classes, particularly the most preferred size class, 3045 mm. Ventral shell thickness and colour had independent effects on mussel selection. The other two variables, number of barnacles and shape of the ventral surface (flat or curved), apparently had no influence on selection on their own, only by way of their association with colour or thickness.
Foraging and movement paths of female reindeer: insights from fractal analysis, correlated random walks, and Lévy flights
Authors: Mårell Anders , Ball John P , Hofgaard Annika
Published: July 2002

Food-plant and foraging-site selection by semidomesticated female reindeer (Rangifer tarandus tarandus L.) was studied to shed light on the searching and foraging behaviour of this herbivore. The aims of the study were (i) to determine the role of food biomass and (or) plant nitrogen content in feeding-site selection and (ii) to analyse the extent to which movement patterns of reindeer are related to availability of food resources using several models of searching behaviour (fractal analysis, correlated random walks, and Lévy flights). The study was conducted in summer 1999 in a mountainous area of northern Sweden. Reindeer selected different plant communities during this period and changed search pattern in late summer. We found that reindeer selected feeding sites with higher green biomass of Betula spp. and Salix spp. However, there was no sharp threshold for foraging as suggested by some models. Contrary to qualitative predictions of optimal-foraging theory, we found no selection of feeding sites on the basis of the nitrogen content of food. The changed search pattern in late summer and the discrepancy between reindeer foraging paths and a correlated random walk model suggests that reindeer were responding to their environment by changing their searching behaviour.
α1-Antitrypsin polymorphism and systematics of eastern North American wolves
Authors: Mech L David , Federoff Nicholas E
Published: July 2002

We used data on the polymorphic status of α1-antitrypsin (α1AT) to study the relationship of Minnesota wolves to the gray wolf (Canis lupus), which was thought to have evolved in Eurasia, and to red wolves (Canis rufus) and coyotes (Canis latrans), which putatively evolved in North America. Recent evidence had indicated that Minnesota wolves might be more closely related to red wolves and coyotes. Samples from wild-caught Minnesota wolves and from captive wolves, at least some of which originated in Alaska and western Canada, were similarly polymorphic for α1AT, whereas coyote and red wolf samples were all monomorphic. Our findings, in conjunction with earlier results, are consistent with the Minnesota wolf being a gray wolf of Eurasian origin or possibly a hybrid between the gray wolf of Eurasian origin and the proposed North American wolf.
Structural organization of the midgut musculature in black flies (Simuliumspp.)
Authors: Koehler Anne , Zia Christina , Desser Sherwin S
Published: July 2002

The structural organization of the midgut musculature of females of the ornithophilic species Simulium rugglesi and the mammalophilic species Simulium venustum were examined by confocal microscopy. In addition, the association between the longitudinal and circular muscles of fed S. rugglesi was investigated by transmission electron microscopy. Longitudinal and circular muscles in both species are arranged orthogonally, forming a gridlike pattern. In S. rugglesi the estimated number of longitudinal and circular muscles was 181 and 90, respectively, whereas in S. venustum there were approximately 156 longitudinal and 69 circular muscles. Longitudinal muscles are arranged in unevenly spaced sets of parallel bundles. Branching of longitudinal muscles occurs randomly along the length of the midgut in S. rugglesi and anteriorly and posteriorly to the most expanded region of the posterior midgut in S. venustum. Circular muscles exhibit less variation in bundle spacing and a more organized branching pattern. Each circular muscle bundle shares fibers with the neighboring bundles, interconnecting them along the length of the midgut. Ultrastructural observations on the midgut of S. rugglesi showed connections between longitudinal and circular muscles. A comparison of the findings from this study with those from studies on mosquitoes revealed similarities in the arrangement and structure of the midgut musculature.
MINIMIZING CONGESTION OF LAYOUTS FOR ATM NETWORKS WITH FAULTY LINKS
Authors: GASIENIEC LESZEK , KRANAKIS EVANGELOS , KRIZANC DANNY , PELC ANDREZEJ
Published: July 2002

We consider the problem of constructing virtual path layouts for an ATM network consisting of a complete network Kn of n processors in which a certain number of links may fail. Our main goal is to construct layouts which tolerate any configuration of up to f faults and have the least possible congestion. First, we study the minimal congestion of 1-hop f-tolerant layouts in Kn. For any positive integer f we give upper and lower bounds on this minimal congestion and construct f-tolerant layouts with congestion corresponding to the upper bounds. Our results are based on a precise analysis of the diameter of the network Kn[ℱ] which results from Kn by deleting links from a set ℱ of bounded size. Next we study the minimal congestion of h-hop f-tolerant layouts in Kn, for larger values of the number h of hops. We give upper and lower bounds on the order of magnitude of this congestion, based on results for 1-hop layouts. Finally, we consider a random, rather than worst case, fault distribution where links fail independently with constant probability p<1. Our goal now is to construct layouts with low congestion that tolerate the existing faults with high probability. For any p<1, we show the existence of 1-hop layouts in Kn, with congestion O( log n).
THEORY OF THRESHOLD CHARACTERISTICS OF QUANTUM DOT LASERS: EFFECT OF QUANTUM DOT PARAMETER DISPERSION
Authors: ASRYAN LEVON V. , SURIS ROBERT A.
Published: July 2002

Gain and threshold current of a quantum dot (QD) laser are analyzed theoretically taking into account the inhomogeneous line broadening caused by fluctuations in QD parameters. Two regions of QD filling by carriers, nonequilibrium and equilibrium, are identified, depending on temperature, barrier heights and QD size. Critical tolearable parameters of the QD structure, at which lasing becomes impossible to attain, are shown to exist. The minimum threshold current density and optimum parameters are calculated. Violation of charge neutrality in QDs is revealed, which affects significantly the threshold current and its temperature dependence. The gain-current dependence is calculated. The voltage dependences of the electron and hole level occupancies in QDs, gain and current are obtained. The observed temperature dependence of threshold current (constant at low temperatures and rapid increase above a certain temperature) is predicted and explained. Violation of charge neutrality is shown to give rise to the slight temperature dependence of the current component associated with the recombination in QDs. The characteristic temperature T0 is calculated considering carrier recombination in the optical confinement layer and violation of charge neutrality in QDs. The inclusion of violation of charge neutrality is shown to be critical for the correct calculation of T0 at low T. T0 is shown to fall off profoundly with increasing T. Theoretical estimations confirm the possibility of a significant reduction of the threshold currents and enhancement of T0 of QD lasers as compared with the conventional quantum wall (QW) lasers. Longitudinal spatial hole burning is analyzed. Unlike QW lasers, thermally excited escapes of carrier from QDs, rather than diffusion, are shown to control the smoothing-out of the spatially nonuniform population inversion and multimode generation in QD lasers. A decrease in the QD size dispersion is shown not only to decrease the threshold current but to increase considerably the relative multimode generation threshold as well. Concurrent with the increase of threshold current, an increase of the multimode generation threshold is shown to occur with a rise in temperature. Ways to optimize the QD laser, aimed at maximizing the multimode generation threshold, are outlined.
COMPLETE CLASSIFICATION OF SPECTRAL OPERATOR ALGEBRAS ASSOCIATED WITH DIVISIBLE PRODUCT SYSTEMS
Authors: AOTANI MASAYASU
Published: July 2002

Completely spatial E0-semigroups constitute the most important class of E0-semigroups. Each completely spatial E0-semigroup α induces a divisible product system Eα and a C*-algebra C*(Eα) called the spectral C*-algebra. It has been shown by Arveson that Eα and Eβ are isomorphic as product systems if and only if α and β are cocycle conjugate. He has also proved that representations of E correspond bijectively to ordinary C*-algebraic representations of C*(E). While it is trivial to show that C*(Eα) and C*(Eβ) are isomorphic if the underlying product systems Eα and Eβ are isomorphic, it is not known whether C*(Eα) and C*(Eβ) can be isomorphic when Eα and Eβ are not. In this paper we will consider a related isomorphism problem among the Banach algebras, known as spectral operator algebras, associated with divisible product systems. It will be shown that the spectral operator algebras [Formula: see text] and [Formula: see text] are isomorphic if and only if Eα and Eβ are isomorphic. This classification is important as C*(E) is a hereditary subalgebra of the C*-algebra [Formula: see text] generated by [Formula: see text].
DIOPHANTINE DEFINABILITY OVER HOLOMORPHY RINGS OF ALGEBRAIC FUNCTION FIELDS WITH INFINITE NUMBER OF PRIMES ALLOWED AS POLES
Authors: SHLAPENTOKH ALEXANDRA
Published: July 2002

Let K be an algebraic function field over a finite field of constants of characteristic greater than 2. Let W be a set of non-archimedean primes of K, let [Formula: see text]. Then for any finite set S of primes of K there exists an infinite set W of primes of K containing S, with the property that OK,Shas a Diophantine definition over OK,W.
NUCLEON DISTRIBUTIONS AT NUCLEAR PERIPHERY
Authors: GAMBHIR Y. K. , BHAGWAT A. A.
Published: July 2002

The experimental ratios of the neutron to the proton densities at the nuclear periphery (≃ half-density radius + 2.5 fm) determined using very low energy anti-proton annihilation studies are compared with the predictions of the semi-phenomenological model of the nucleon density distributions. The model incorporates correctly two physical requirements: the correct asymptotic behavior (r → ∞) and the behavior near the center (r → 0).

The model gives a good account of the experiment. The results of the more sophisticated, microscopic mean field calculations like non-relativistic Hartree–Fock–Bogoliubov (HFB) with Skyrme type interactions though are qualitatively similar, the model density results are relatively closer to the experiment.
INTERSECTING MEMBRANES FROM CHARGED MACROSCOPIC STRINGS
Authors: BISWAS ANINDYA , PANIGRAHI KAMAL LOCHAN
Published: July 2002

We present a class of orthogonal membrane configurations which preserve 1/4 of the full type IIA supersymmetry. These membrane configurations carry additional F-string charges. We further analyze the D1–D3 configuration after applying T-duality along the world volume directions of the above orthogonal membranes.
THE EUCLIDEAN PROPAGATOR IN A MODEL WITH TWO NON-EQUIVALENT INSTANTONS
Authors: CASAHORRÁN J.
Published: July 2002

We consider in detail how the quantum-mechanical tunneling phenomenon occurs in a well-behaved octic potential. Our main tool will be the Euclidean propagator just evaluated between two minima of the potential at issue. For such a purpose we resort to the standard semiclassical approximation which takes into account the fluctuations over the instantons, i.e. the finite-action solutions of the Euclidean equation of motion. With respect to the one-instanton approach, the functional determinant associated with the so-called stability equation is analyzed in terms of the asymptotic behavior of the zero-mode. The conventional ratio of determinants takes as reference the harmonic oscillator whose frequency is the average of the two different frequencies derived from the minima of the potential involved in the computation. The second instanton of the model is studied in a similar way. The physical effects of the multi-instanton configurations are included in this context by means of the alternate dilute-gas approximation where the two instantons participate to give the final expression of the propagator.
CREATION OF A WORMHOLE DUE TO NONLINEAR ELECTRODYNAMICS
Authors: FONSECA-BARBATTI CARLA , NOVELLO M. , SALIM J. M. , ARCURI REGINA C.
Published: July 2002

We obtain a new class of solutions for the Einstein field equations which describe wormholes by using the one-loop effective Lagrangian of quantum electrodynamics. We also show that the derived wormholes can be maintained only by means of a magnetic field.
SUPERSYMMETRIC HIGGS TRIPLETS AND BILINEAR R-PARITY NONCONSERVATION
Authors: MA ERNEST
Published: July 2002

The supersymmetric standard model of particle interactions is extended to include two Higgs triplet superfields at the TeV scale, carrying two units of lepton number. Realistic tree-level Majorana neutrino masses are obtained in the presence of soft, i.e. bilinear, R-parity nonconservation.
A NOTE ON THE AVERAGING TECHNIQUE IN SU(N) GAUGE THEORY
Authors: SUN WEI-MIN , WANG FAN
Published: July 2002

In this paper we apply the averaging technique (using a right-invariant local gauge group measure) to local polynomials of the SU (N) gauge potential [Formula: see text] and show that the results are divergent and ill-defined.
TUNNELING EFFECTS IN A BRANE SYSTEM AND QUANTUM HALL PHYSICS
Authors: CAPPIELLO LUIGI , CRISTOFANO GERARDO , MAIELLA GIUSEPPE , MAROTTA VINCENZO
Published: July 2002

We argue that a system of interacting D-branes, generalizing a recent proposal, can be modeled as a quantum Hall fluid. We show that tachyon condensation in such a system is equivalent to one-particle tunneling. In a conformal field theory effective description, that induces a transition from a theory with central charge c = 2 to a theory with c = 3/2, with a corresponding symmetry enhancement.
LORENTZ COVARIANCE FOR THE QUANTUM ALGEBRA OF OBSERVABLES: NAMBU–GOTO STRINGS IN 3 + 1 DIMENSIONS
Authors: HANDRICH GERRIT
Published: July 2002

To postulate correspondence for the observables only is a promising approach to a fully satisfying quantization of the Nambu–Goto string. The relationship between the Poisson algebra of observables and the corresponding quantum algebra is established in the language of generators and relations. A very valuable tool is the transformation to the string's rest frame, since a substantial part of the relations are solved. It is the aim of this paper to clarify the relationship between the fully covariant and the rest frame description. Both in the classical and in the quantum case, an efficient method for recovering the covariant algebra from the one in the rest frame is described. Restrictions on the quantum defining relations are obtained, which are not taken into account when one postulates correspondence for the rest frame algebra. For the part of the algebra studied up to now in explicit computations, these further restrictions alone determine the quantum algebra uniquely — in full consistency with the further restrictions found in the rest frame.
INSTANTANEOUS BETHE–SALPETER EQUATION: IMPROVED ANALYTICAL SOLUTION
Authors: LUCHA WOLFGANG , SCHÖBERL FRANZ F.
Published: July 2002

Studying the Bethe–Salpeter formalism for interactions instantaneous in the rest-frame of the bound states described, we show that, for bound-state constituents of arbitrary masses, the mass of the ground state of a given spin may be calculated almost entirely analytically with high accuracy, without the (numerical) diagonalization of the matrix representation obtained by expansion of the solutions over a suitable set of basis states.
SOLUTIONS OF VANISHING CURVATURE NON-ABELIAN MONOPOLE EQUATIONS
Authors: LEGARÉ M.
Published: July 2002

Reduced non-Abelian monopole equations are derived for a set of dimensional reductions, with cases involving supplementary algebraic conditions. (Local) solutions to certain reduced ordinary differential equations of the flat four-dimensional non-Abelian monopole equations are discussed.