bluuebunny/crossref_metadata_2025 huggingface dataset:
PostprenylationCAAXProcessing Is Required for Proper Localization of Ras but Not Rho GTPases
Authors: Michaelson David , Ali Wasif , Chiu Vi K. , Bergo Martin , Silletti Joseph , Wright Latasha , Young Stephen G. , Philips Mark
Published: January 2005

The CAAX motif at the C terminus of most monomeric GTPases is required for membrane targeting because it signals for a series of three posttranslational modifications that include isoprenylation, endoproteolytic release of the C-terminal– AAX amino acids, and carboxyl methylation of the newly exposed isoprenylcysteine. The individual contributions of these modifications to protein trafficking and function are unknown. To address this issue, we performed a series of experiments with mouse embryonic fibroblasts (MEFs) lacking Rce1 (responsible for removal of the –AAX sequence) or Icmt (responsible for carboxyl methylation of the isoprenylcysteine). In MEFs lacking Rce1 or Icmt, farnesylated Ras proteins were mislocalized. In contrast, the intracellular localizations of geranylgeranylated Rho GTPases were not perturbed. Consistent with the latter finding, RhoGDI binding and actin remodeling were normal in Rce1- and Icmt-deficient cells. Swapping geranylgeranylation for farnesylation on Ras proteins or vice versa on Rho proteins reversed the differential sensitivities to Rce1 and Icmt deficiency. These results suggest that postprenylation CAAX processing is required for proper localization of farnesylated Ras but not geranygeranylated Rho proteins.
Characterization of an Arabidopsis Enzyme Family That Conjugates Amino Acids to Indole-3-Acetic Acid
Authors: Staswick Paul E. , Serban Bogdan , Rowe Martha , Tiryaki Iskender , Maldonado Marién T. , Maldonado Mitsa C. , Suza Walter
Published: January 2005

Substantial evidence indicates that amino acid conjugates of indole-3-acetic acid (IAA) function in auxin homeostasis, yet the plant enzymes involved in their biosynthesis have not been identified. We tested whether several Arabidopsis thaliana enzymes that are related to the auxin-induced soybean (Glycine max) GH3 gene product synthesize IAA–amino acid conjugates. In vitro reactions with six recombinant GH3 enzymes produced IAA conjugates with several amino acids, based on thin layer chromatography. The identity of the Ala, Asp, Phe, and Trp conjugates was verified by gas chromatography–mass spectrometry. Insertional mutations in GH3.1, GH3.2, GH3.5, and GH3.17 resulted in modestly increased sensitivity to IAA in seedling root. Overexpression of GH3.6 in the activation-tagged mutant dfl1-D did not significantly alter IAA level but resulted in 3.2- and 4.5-fold more IAA-Asp than in wild-type seedlings and mature leaves, respectively. In addition to IAA, dfl1-D was less sensitive to indole-3-butyric acid and naphthaleneacetic acid, consistent with the fact that GH3.6 was active on each of these auxins. By contrast, GH3.6 and the other five enzymes tested were inactive on halogenated auxins, and dfl1-D was not resistant to these. This evidence establishes that several GH3 genes encode IAA-amido synthetases, which help to maintain auxin homeostasis by conjugating excess IAA to amino acids.
Genetic Analysis Reveals Domain Interactions of Arabidopsis Hsp100/ClpB and Cooperation with the Small Heat Shock Protein Chaperone System
Authors: Lee Ung , Wie Chris , Escobar Mindy , Williams Ben , Hong Suk-Whan , Vierling Elizabeth
Published: January 2005

We have defined amino acids important for function of the Arabidopsis thaliana Hsp100/ClpB chaperone (AtHsp101) in acquired thermotolerance by isolating recessive, loss-of-function mutations and a novel semidominant, gain-of-function allele [hot1-4 (A499T)]. The hot1-4 allele is unusual in that it not only fails to develop thermotolerance to 45°C after acclimation at 38°C, but also is sensitive to 38°C, which is a permissive temperature for wild-type and loss-of-function mutants. hot1-4 lies between nucleotide binding domain 1 (NBD1) and NBD2 in a coiled-coil domain that is characteristic of the Hsp100/ClpB proteins. We then isolated two classes of intragenic suppressor mutations of hot1-4: loss-of-function mutations (Class 1) that eliminated the 38°C sensitivity, but did not restore thermotolerance function to hot1-4, and Class 2 suppressors that restored acquired thermotolerance function to hot1-4. Location of the hot1-4 Class 2 suppressors supports a functional link between the coiled-coil domain and both NBD1 and the axial channel of the Hsp100/ClpB hexamer. In addition, the strongest Class 2 suppressors restored solubility of aggregated small heat shock proteins (sHsps) after heat stress, revealing genetic interaction of the Hsp100/ClpB and sHsp chaperone systems. These results also demonstrate that quantitative phenotypes can be used for in vivo genetic dissection of protein mechanism in Arabidopsis.
PlusandMinusSexual Agglutinins fromChlamydomonas reinhardtii
Authors: Ferris Patrick J. , Waffenschmidt Sabine , Umen James G. , Lin Huawen , Lee Jae-Hyeok , Ishida Koichi , Kubo Takeaki , Lau Jeffrey , Goodenough Ursula W.
Published: January 2005

Gametes of the unicellular green alga Chlamydomonas reinhardtii undergo sexual adhesion via enormous chimeric Hyp-rich glycoproteins (HRGPs), the plus and minus sexual agglutinins, that are displayed on their flagellar membrane surfaces. We have previously purified the agglutinins and analyzed their structural organization using electron microscopy. We report here the cloning and sequencing of the Sag1 and Sad1 genes that encode the two agglutinins and relate their derived amino acid sequences and predicted secondary structure to the morphology of the purified proteins. Both agglutinin proteins are organized into three distinct domains: a head, a shaft in a polyproline II configuration, and an N-terminal domain. The plus and minus heads are related in overall organization but poorly conserved in sequence except for two regions of predicted hydrophobic α-helix. The shafts contain numerous repeats of the PPSPX motif previously identified in Gp1, a cell wall HRGP. We propose that the head domains engage in autolectin associations with the distal termini of their own shafts and suggest ways that adhesion may involve head–head interactions, exolectin interactions between the heads and shafts of opposite type, and antiparallel shaft–shaft interactions mediated by carbohydrates displayed in polyproline II configurations.
Dissection of Arabidopsis ADP-RIBOSYLATION FACTOR 1 Function in Epidermal Cell Polarity
Authors: Xu Jian , Scheres Ben
Published: January 2005

Vesicle trafficking is essential for the generation of asymmetries, which are central to multicellular development. Core components of the vesicle transport machinery, such as ADP-ribosylation factor (ARF) GTPases, have been studied primarily at the single-cell level. Here, we analyze developmental functions of the ARF1 subclass of the Arabidopsis thaliana multigene ARF family. Six virtually identical ARF1 genes are ubiquitously expressed, and single loss-of-function mutants in these genes reveal no obvious developmental phenotypes. Fluorescence colocalization studies reveal that ARF1 is localized to the Golgi apparatus and endocytic organelles in both onion (Allium cepa) and Arabidopsis cells. Apical-basal polarity of epidermal cells, reflected by the position of root hair outgrowth, is affected when ARF1 mutants are expressed at early stages of cell differentiation but after they exit mitosis. Genetic interactions during root hair tip growth and localization suggest that the ROP2 protein is a target of ARF1 action, but its localization is slowly affected upon ARF1 manipulation when compared with that of Golgi and endocytic markers. Localization of a second potential target of ARF1 action, PIN2, is also affected with slow kinetics. Although extreme redundancy precludes conventional genetic dissection of ARF1 functions, our approach separates different ARF1 downstream networks involved in local and specific aspects of cell polarity.
Factors shaping the range‐size frequency distribution of the endemic fish fauna of the Tropical Eastern Pacific
Authors: Mora Camilo , Ross Robertson D.
Published: January 2005

Aim To assess the effect of habitat fragmentation and isolation in determining the range‐size frequency distribution (RFD) of the shorefish fauna endemic to a discrete biogeographical region.

Location The Tropical Eastern Pacific (TEP).

Methods Habitat isolation represents the separation between oceanic islands and the continental shore of the TEP and habitat fragmentation the degree of spatial continuity of habitats (i.e. reefs, soft bottom, nearshore waters) along the continental coast of the TEP. The effects of habitat isolation and fragmentation were quantified by comparing the RFDs of (1) the species found on oceanic islands vs. the continental shore, and (2) species on the continental shore that use different habitat types.

Results The RFD of the entire TEP fauna was bimodal, with peaks at both small‐ and large‐range ends of the spectrum. The small‐range peak was due almost entirely to island species and the large‐range peak due mainly to species found in both the continental shore and oceanic islands. RFDs varied among species using different habitats on the continental shore: reef‐fishes had a right‐skewed RFD, soft‐bottom species a flat RFD, and coastal‐pelagic fishes a left‐skewed RFD.

Main conclusions Variation in dispersal capabilities associated with habitat isolation and fragmentation in the TEP appears to be the main mechanism contributing to differences among RFD structure, although variation in tolerances arising from the dynamic regional environment may contribute to some patterns. Because diversity patterns are strongly affected by RFD structure, it is now evident that the insular and continental components of a fauna should be treated separately when analysing such patterns. Furthermore, contrasts in RFD structure among species using different habitats demonstrate that a full understanding of the causes of diversity patterns requires analyses of complete regional faunas in relation to regional geography.
The biogeography of otophysan fishes (Ostariophysi: Otophysi): a new appraisal
Authors: Briggs John C.
Published: January 2005

Aim  To present a new hypothetical history of the otophysan fishes.

Location  World‐wide.

Methods  Utilization of recent information about otophysan phylogeny, palaeontology, biogeography and external relations.

Results  Anatomical, mitochondrial DNA and karological research has indicated that the Cypriniformes is the most primitive of the four orders that comprise the Otophysi. The Siluriformes is next in the phylogenetic progression followed by the Characiformes and the Gymnotiformes. A molecular clock estimate indicated that the divergence time between the cypriniforms and the remaining otophysans took place about 250 Ma. But, otophysans have apparently never occurred on Madagascar‐India and that land mass did not separate from Africa until 158–160 Ma. As we know that some otophysans existed in Africa–South America prior to 115 Ma, they must have originated between 115 and 160 Ma.

Main conclusions  Comparison of phylogeny and biogeography appears to indicate that the Otophysi originated in South America, the location of the apomorphic Gymnotiformes. It seems that the gymnotiforms did not radiate in time to get across to Africa and the characiforms did not expand in time to catch the connection to Asia. Apparently, it was only the ancestors to the cypriniform and siluriform lines that expanded early enough to reach Asia in the late Jurassic. There remains a gap of about 80 Myr between the oldest known otophysan fossil and the approximate time of dispersal to Asia. Further progress awaits more phylogenetic or fossil discoveries.
Nonparametric Estimation of the Hazard Function by Using a Model Selection Method: Estimation of Cancer Deaths in Hiroshima Atomic Bomb Survivors
Authors: Martin-Magniette M. L.
Published: January 2005

Controversy has intensified regarding the death-rate from cancer that is induced by a dose of radiation. In the models that are usually considered the hazard function is an increasing function of the dose of radiation. Such models can mask local variations. We consider the models of excess relative risk and of absolute risk and propose a nonparametric estimation of the effect of the dose by using a model selection procedure. This estimation deals with stratified data. We approximate the function of the dose by a collection of splines and select the best one according to the Akaike information criterion. In the same way between the models of excess relative risk or excess absolute risk, we choose the model that best fits the data. We propose a bootstrap method for calculating a pointwise confidence interval of the dose function. We apply our method for estimating the solid cancer and leukaemia death hazard functions to Hiroshima.
Inference in Disease Transmission Experiments by Using Stochastic Epidemic Models
Authors: Höhle Michael , Jørgensen Erik , O’Neill Philip D.
Published: January 2005

The paper extends the susceptible–exposed–infective–removed model to handle heterogeneity introduced by spatially arranged populations, biologically plausible distributional assumptions and incorporation of observations from additional diagnostic tests. These extensions are motivated by a desire to analyse disease transmission experiments in a more detailed fashion than before. Such experiments are performed by veterinarians to gain knowledge about the dynamics of an infectious disease. By fitting our spatial susceptible–exposed–infective–removed with diagnostic testing model to data for a specific disease and production environment a valuable decision support tool is obtained, e.g. when evaluating on-farm control measures. Partial observability of the epidemic process is an inherent problem when trying to estimate model parameters from experimental data. We therefore extend existing work on Markov chain Monte Carlo estimation in partially observable epidemics to the multitype epidemic set-up of our model. Throughout the paper, data from a Belgian classical swine fever virus transmission experiment are used as a motivating example.
Design and Analysis of Variable Fidelity Experimentation Applied to Engine Valve Heat Treatment Process Design
Authors: Huang Deng , Allen Theodore T.
Published: January 2005

When experimentation on a real system is expensive, data are often collected by using cheaper, lower fidelity surrogate systems. The paper concerns response surface methods in the context of variable fidelity experimentation. We propose the use of generalized least squares to generate the predictions. We also present perhaps the first optimal designs for variable fidelity experimentation, using an extension of the expected integrated mean-squared error criterion. Numerical tests are used to compare the performance of the method with alternatives and to investigate the robustness to incorporated assumptions. The method is applied to automotive engine valve heat treatment process design in which real world data were mixed with data from two types of computer simulation.
Chemical, pharmacokinetic and pharmacodynamic properties of statins: an update
Authors: Schachter Michael
Published: January 2005

Statins are the treatment of choice for the management of hypercholesterolaemia because of their proven efficacy and safety profile. They also have an increasing role in managing cardiovascular risk in patients with relatively normal levels of plasma cholesterol. Although all statins share a common mechanism of action, they differ in terms of their chemical structures, pharmacokinetic profiles, and lipid‐modifying efficacy. The chemical structures of statins govern their water solubility, which in turn influences their absorption, distribution, metabolism and excretion. Lovastatin, pravastatin and simvastatin are derived from fungal metabolites and have elimination half‐lives of 1–3 h. Atorvastatin, cerivastatin (withdrawn from clinical use in 2001), fluvastatin, pitavastatin and rosuvastatin are fully synthetic compounds, with elimination half‐lives ranging from 1 h for fluvastatin to 19 h for rosuvastatin. Atorvastatin, simvastatin, lovastatin, fluvastatin, cerivastatin and pitavastatin are relatively lipophilic compounds. Lipophilic statins are more susceptible to metabolism by the cytochrome P450 system, except for pitavastatin, which undergoes limited metabolism via this pathway. Pravastatin and rosuvastatin are relatively hydrophilic and not significantly metabolized by cytochrome P450 enzymes. All statins are selective for effect in the liver, largely because of efficient first‐pass uptake; passive diffusion through hepatocyte cell membranes is primarily responsible for hepatic uptake of lipophilic statins, while hydrophilic agents are taken up by active carrier‐mediated processes. Pravastatin and rosuvastatin show greater hepatoselectivity than lipophilic agents, as well as a reduced potential for uptake by peripheral cells. The bioavailability of the statins differs greatly, from 5% for lovastatin and simvastatin to 60% or greater for cerivastatin and pitavastatin. Clinical studies have demonstrated rosuvastatin to be the most effective for reducing low‐density lipoprotein cholesterol, followed by atorvastatin, simvastatin and pravastatin. As a class, statins are generally well tolerated and serious adverse events, including muscle toxicity leading to rhabdomyolysis, are rare. Consideration of the differences between the statins helps to provide a rational basis for their use in clinical practice.
Herb–drug interactions: an overview of the clinical evidence
Authors: Izzo Angelo A.
Published: January 2005

Herbal medicines are mixtures of more than one active ingredient. The multitude of pharmacologically active compounds obviously increases the likelihood of interactions taking place. Hence, the likelihood of herb–drug interactions is theoretically higher than drug–drug interactions, if only because synthetic drugs usually contain single chemical entities. Case reports and clinical studies have highlighted the existence of a number of clinically important interactions, although cause‐and‐effect relationships have not always been established. Herbs and drugs may interact either pharmacokinetically or pharmacodynamically. Through induction of cytochrome P450 enzymes and/or P‐glycoprotein, some herbal products (e.g. St John's wort) have been shown to lower the plasma concentration (and/or the pharmacological effect) of a number of conventional drugs, including cyclosporine, indinavir, irinotecan, nevirapine, oral contraceptives and digoxin. The majority of such interactions involves medicines that require regular monitoring of blood levels. To date there is less evidence relating to the pharmacodynamic interaction. However, for many of the interactions discussed here, the understanding of the mechanisms involved is incomplete. Taking herbal agents may represent a potential risk to patients under conventional pharmacotherapy.
How appropriate is asthma therapy in general practice?
Authors: Laforest Laurent , Pacheco Yves , Bousquet Jean , Sazonov Kocevar Vasilisa , Yin Don , Van Ganse Eric
Published: January 2005

High association between burden of asthma and inadequate disease control make asthma management a major public health issue. We studied asthma management practices of general practitioners (GPs) in France to describe drug therapy and more specifically, to identify correlates of antibiotic prescriptions, a marker of inappropriate asthma management. Patients with persistent asthma aged 17–50 years were evaluated in a 12‐month retrospective study using a computerized GPs database (Thales) and a patient survey, in which patients reported hospital contacts, use of oral corticosteroids and recent asthma symptoms. Therapy was described and the correlates of antibiotic prescriptions in the previous year were identified using multivariate logistic regression. During the study period, 16.4% of 1038 patients received one or more prescriptions of theophylline, 31.3% long‐acting beta‐agonists and 61.6% inhaled corticosteroids. Rates of prescription of antibiotics, expectorants, antihistamines, antitussives and nasal corticosteroids were 57.6, 42.0, 33.0, 19.9, and 14.4%, respectively. In parallel, 15% of patients reported at least one hospital contact for asthma and 43.1% used oral corticosteroids. Antibiotic prescriptions were more likely co‐prescribed in patients using expectorants [odds ratio (OR) = 13.0, 95% confidence interval (CI) = 8.5–19.8] and antitussives (OR = 6.5, 95% CI =3.7–11.6). Moreover, patients using courses of oral corticosteroids, and often visiting their GP (more than four times) during the study period were more likely to receive antibiotics. The results were unchanged when analyses were restricted to non‐smokers and younger patients (≤40 years). Asthma management was sub‐optimal among asthma patients treated by general practitioners in France. Antibiotics, expectorants, antihistamines, antitussives and nasal corticosteroids were commonly prescribed while asthma controllers were under‐used.
CYP2C9 and CYP2C19 genetic polymorphisms: frequencies in the south Indian population
Authors: Jose Rosemary , Chandrasekaran Adithan , Sam Soya Sisy , Gerard Nathalie , Chanolean Shashindran , Abraham Benny K. , Satyanarayanamoorthy K. , Peter Anitha , Rajagopal Krishnamoorthy
Published: January 2005

The aim of the study was to establish the frequencies of CYP2C9*1, *2, *3 and CYP2C19*1, *2 and *3 in the south Indian population and to compare them with the inter‐racial distribution of the CYP2C9 and CYP2C19 genetic polymorphisms. Genotyping analyses of CYP2C9 and CYP2C19 were conducted in unrelated, healthy volunteers from the three south Indian states of Andhra Pradesh, Karnataka and Kerala, by the polymerase chain reaction–restriction fragment‐length polymorphism (PCR–RFLP). The allele frequencies of the populations of these three states were then pooled with our previous genotyping data of Tamilians (also in south India), to arrive at the distribution of CYP2C9 and CYP2C19 alleles in the south Indian population. Frequencies of CYP2C9 and CYP2C19 alleles and genotypes among various populations were compared using the two‐tailed Fisher's exact test. The frequencies of CYP2C9*1, *2 and *3 in the south Indian population were 0.88 (95% CI 0.85–0.91), 0.04 (95% CI 0.02–0.06) and 0.08 (95% CI 0.06–0.11), respectively. The frequencies of CYP2C9 genotypes *1/*1, *1/*2, *1/*3, *2/*2, *2/*3 and *3/*3 were 0.78 (95% CI 0.74–0.82), 0.05 (95% CI 0.03–0.07), 0.15 (95% CI 0.12–0.18), 0.01 (95% CI 0.0–0.02), 0.01 (95% CI 0.0–0.02) and 0.0, respectively. CYP2C19*1, *2 and *3 frequencies were 0.64 (95% CI 0.60–0.68), 0.35 (95% CI 0.31–0.39) and 0.01 (95% CI 0.0–0.03), respectively. As a result of a significant heterogeneity, the data on CYP2C19 genotype frequencies were not pooled. The frequency of CYP2C9*2 mutant alleles in south Indians was higher than in Chinese and Caucasians, while CYP2C9*3 was similar to Caucasians. CYP2C19*2 was higher than in other major populations reported so far. The relatively high CYP2C19 poor‐metabolizer genotype frequency of 12.6% indicates that over 28 million south Indians are poor metabolizers of CYP2C19 substrates.
Experimental evidence for in vitro fluid transport in the presence of a traditional medicinal fruit extract across rat everted intestinal sacs
Authors: Mahomoodally Mohamad Fawzi , Gurib‐Fakim Ameenah , Subratty Anwar Hussein
Published: January 2005

The present study was designed to investigate the effects of aqueous fruit extract of Momordica charantia (MC), a traditional medicinal plant, on the transport of fluid in vitro. Everted intestinal sacs from rats were mounted in an organ bath containing Krebs solution. We compared the effect of MC extract on water transport with increasing inorganic phosphate concentration with or without d‐glucose in the buffer. In the control experiments, fluid uptake was enhanced significantly (P < 0.05) at high inorganic phosphate concentration (8–10 mm) in the presence of 5.5 mmd‐glucose. Addition of 3.0 mg/mL MC extract to the serosal side inhibits the uptake of fluid significantly (P < 0.05). At high inorganic phosphate concentration (8–10 mm), fluid uptake was not inhibited (P > 0.05) when incubated with 3.0 mg/mL MC fruit extract. It is hypothesized that an increase in inorganic phosphate enhances oxidative phosphorylation thereby increasing the fluid uptake across everted intestinal sacs of rat. These findings seem to indicate that the MC‐induced reduction on intestinal fluid absorption capacity could be mainly the result of an interference with the carrier‐mediated coupled entrance of glucose and Na+ across the brush‐border membrane.
Minimum shear wind strength required for dynamic soaring of albatrosses
Authors: SACHS GOTTFRIED
Published: January 2005

The transfer of energy from the moving air in the shear wind above the sea surface to a bird is considered as an energy source for dynamic soaring, with the goal to determine the minimum shear wind strength required for the dynamic soaring of albatrosses. Focus is on energy‐neutral trajectories, implying that the energy gain from the moving air is just sufficient to compensate for the energy loss due to drag for a dynamic soaring cycle. A mathematical optimization method is used for computing minimum shear wind energy‐neutral trajectories, using a realistic flight mechanics model for the soaring of albatrosses. Thus, the minimum shear wind strength required for dynamic soaring is determined. The minimum shear wind strength is of a magnitude that often exists or is exceeded in areas in which albatrosses are found. This result holds for two control cases dealt with, one of which shows a freely selectable and the other a constant lift coefficient characteristic. The mechanism of energy transfer from the shear flow to the bird is considered, and it is shown that there is a significant energy gain in the upper curve and a loss in the lower curve. As a result, the upper curve can be qualified as the characteristic flight phase of dynamic soaring to achieve an energy gain.
The effect of habitat quality on foraging patterns, provisioning rate and nestling growth in Corsican Blue Tits Parus caeruleus
Authors: TREMBLAY ISABELLE , THOMAS DONALD , BLONDEL JACQUES , PERRET PHILIPPE , LAMBRECHTS MARCEL M.
Published: January 2005

Many bird species face seasonal and spatial variation in the availability of the specific food required to rear chicks. Caterpillar availability is often identified as the most important factor determining chick quality and breeding success in forest birds, such as tits Parus spp. It is assumed that parents play an important role in mediating the effect of environment on chick development. A reduction in prey availability should therefore result in increased foraging effort to maintain the amount of food required for optimal chick development. To investigate the capacity of adults to compensate for a reduction in food supply, we compared the foraging behaviour of Blue Tits Parus caeruleus breeding in rich and poor habitats in Corsica. We monitored the foraging effort of adults using radiotelemetry. We also identified and quantified prey items provided to nestlings by using a video camera mounted on the nest. We found that the mean travelling distance of adults was twice as great in the poor habitat as it was in the rich. Despite the marked difference in foraging distance, the proportion of optimal prey (caterpillars) in the diet of the chicks and the total biomass per hour per chick did not differ between the two habitats. We argue that relationships between habitat richness, offspring quality and breeding success cannot be understood adequately without quantifying parental effort.
Food‐niche differentiation in sympatric HenCircus cyaneusand Montagu's HarriersCircus pygargus
Authors: GARCIA J. T. , ARROYO B. E.
Published: January 2005

Hen HarriersCircus cyaneusand Montagu's HarriersCircus pygargusare medium‐sized raptors that differ in size (Hen Harrier being slightly bigger than Montagu's Harrier) and breeding system (Montagu's Harriers are semi‐colonial and Hen Harriers defend nesting–hunting territories). In contrast, the diets of the two species when in sympatry are very similar. We evaluated food‐niche differentiation among these coexisting raptor species and how between‐species differences in body size and social system influence interspecific relationships. We present data from a study conducted in 1997 and 1998 in northeastern Madrid province (central Spain). Diet of the two species largely overlapped (55–95%) during the breeding season, but Hen Harriers preyed more often on larger species. This segregation was observed both in the average size of the primary prey (lagomorphs) and in the alternative prey (birds for Hen Harriers vs. insects for Montagu's Harriers), and was particularly apparent late in the season. Accordingly, feeding frequency of Montagu's Harriers, but not of Hen Harriers, increased later in the season. Size differences between species in prey brought to the nest were apparent for both males and females. Foraging behaviour also differed, as Hen Harriers spent more time hunting close to the nest than did Montagu's Harriers. This implies that segregation in foraging areas may also exist. Observed niche partitioning may relax the potential for competition between these species.
The Forest Owlet Heteroglaux blewitti: vocalization, breeding biology and conservation
Authors: ISHTIAQ FARAH , RAHMANI ASAD R.
Published: January 2005

The little‐known, endemic Forest Owlet Heteroglaux blewitti was studied from June 1998 to June 1999 in Maharashtra, India. Vocalizations associated with contact, courtship feeding and food solicitation were recorded and sonagrams are presented for the first time. The nesting period started in October 1998 and continued until May 1999. Four nests were located and three were monitored for intensive studies on the breeding biology. Thirty days were spent on incubation (n = 2), mainly performed by the female while the male supplied food to the female and chicks. The observed brood size was two. The chicks fledged at 40 days but were dependent on their parents for food and protection for a further 45 days. The very low population density of the species could be due to degraded and fragmented habitat, scarcity of nest‐sites or cronism observed in the species.
Seasonal clutch size variation of multi‐brooded bird species: comparisons between breeding season and latitudes
Authors: GIL‐DELGADO JOSÉ A. , MARCO EVA , PAREDES MARIADELA , VIVES‐FERRÁNDIZ CARMEN
Published: January 2005

Single‐ and multi‐brooded species of birds differ in their seasonal patterns of clutch size. Single‐brooded species start with a maximum clutch size that declines continuously as the season progresses, whereas the clutch sizes of multi‐brooded species usually increase to a mid‐season maximum peak and then decrease progressively until the end of the breeding season. Previous studies have shown that multi‐brooded migrant species present seasonal patterns that are similar to single‐brooded species at high latitudes but similar to multi‐brooded non‐migratory species at lower latitudes. We studied the Greenfinch Carduelis chloris and Goldfinch C. carduelis populations in eastern Spain (Sagunto, Valencia) between 1975 and 2002 to compare seasonal variations in clutch sizes between years with early and late starts to the breeding season. The period over which clutch sizes increase was longer when the breeding season started earlier. The Goldfinch population showed no pattern of initial increase in clutch size when there was a late start to the breeding season: a late start shortens the season giving them less time to breed, and may also coincide with maximum food availability. Thus, the pattern of single‐brooded species was observed. In the Greenfinch population, a trend toward the seasonal pattern of single‐brooded species was also observed when the following indices were compared: clutch size increase, modal timing, initial slope and timing of maximum clutch size. We have also compared the seasonal patterns of clutch size of both species in eastern Spain with the patterns observed in Britain. Our results show that for both Goldfinches and Greenfinches, the non‐migrant southern populations of Sagunto in eastern Spain do not tend towards a more multi‐brooded seasonal pattern of clutch size than the migrant Goldfinches of Britain.
Avian distribution in treefall gaps and understorey ofterra firmeforest in the lowland Amazon
Authors: M. WUNDERLE JOSEPH , WILLIG MICHAEL R. , PINTO HENRIQUES LUIZA MAGALLI
Published: January 2005

We compared the bird distributions in the understorey of treefall gaps and sites with intact canopy in Amazonianterra firmeforest in Brazil. We compiled 2216 mist‐net captures (116 species) in 32 gap and 32 forest sites over 22.3 months. Gap habitats differed from forest habitats in having higher capture rates, total captures, species richness and diversity. Seventeen species showed a significantly different distribution of captures between the two habitats (13 higher in gap and four higher in forest). Gap habitats had higher capture rates for nectarivores, frugivores and insectivores. Among insectivores, capture rates for solitary insectivores and army ant followers did not differ between the two habitats. In contrast, capture rates were higher in gaps for members of mixed‐species insectivore flocks and mixed‐species insectivore–frugivore flocks. Insectivores, especially members of mixed‐species flocks, were the predominant species in gap habitats, where frugivores and nectarivores were relatively uncommon. Although few canopy species were captured in gap or forest habitats, visitors from forest mid‐storey constituted 42% of the gap specialist species (0% forest) and 46% of rare gap species (38% forest). Insectivore, and total, captures increased over time, but did so more rapidly in gap than in forest habitats, possibly as a response to gap succession. However, an influx of birds displaced by nearby timber harvest also may have caused these increases. Avian gap‐use in Amazonianterra firmeforests differs from gap‐use elsewhere, partly because of differences in forest characteristics such as stature and soil fertility, indicating that the avian response to gaps is context dependent.
Biodemographic analysis of male honey bee mortality
Authors: Rueppell Olav , Fondrk M. Kim , E. Page Robert
Published: January 2005

Biodemographic studies of insects have significantly enhanced our understanding of the biology of aging. Eusocial insects have evolved to form different groups of colony members that are specialized for particular tasks and highly dependent on each other. These different groups (castes and sexes) also differ strongly in their life expectancy but relatively little is known about their mortality dynamics. In this study we present data on the age‐specific flight activity and mortality of male honey bees from two different genetic lines that are exclusively dedicated to reproduction. We show that males initiating flight at a young age experience more flight events during their lifetime. No (negative) relation between the age at flight initiation and lifespan exists, as might be predicted on the basis of the antagonistic pleiotropy theory of aging. Furthermore, we fit our data to different aging models and conclude that overall a slight deceleration of the age‐dependent mortality increase at advanced ages occurs. However, mortality risk increases according to the Gompertz–Makeham model when only days with flight activity (active days) are taken into account. Our interpretation of the latter is that two mortality components act on honey bee males during flight: increasing, age‐dependent deaths (possibly from wear‐and‐tear), and age‐independent deaths (possibly due to predation). The overall mortality curve is caused by the interaction of the distribution of age at foraging initiation and the mortality function during the active (flight) lifespan.
Diabetes, Obesity, and the Brain
Authors: Schwartz Michael W. , Porte Daniel
Published: January 2005

Recent evidence suggests a key role for the brain in the control of both body fat content and glucose metabolism. Neuronal systems that regulate energy intake, energy expenditure, and endogenous glucose production sense and respond to input from hormonal and nutrient-related signals that convey information regarding both body energy stores and current energy availability. In response to this input, adaptive changes occur that promote energy homeostasis and the maintenance of blood glucose levels in the normal range. Defects in this control system are implicated in the link between obesity and type 2 diabetes.
Type 2 Diabetes-a Matter of ß-Cell Life and Death?
Authors: Rhodes Christopher J.
Published: January 2005

In type 2 diabetes, the β cells of the pancreas fail to produce enough insulin to meet the body's demand, in part because of an acquired decrease in β-cell mass. In adults, pancreatic β-cell mass is controlled by several mechanisms, including β-cell replication, neogenesis, hypertrophy, and survival. Here, I discuss evidence supporting the notion that increased β-cell apoptosis is an important factor contributing to β-cell loss and the onset of type 2 diabetes. Interestingly, a key signaling molecule that promotes β-cell growth and survival, insulin receptor substrate 2 (IRS-2), is a member of a family of proteins whose inhibition contributes to the development of insulin resistance in the liver and other insulin-responsive tissues. Thus, the IRS-2 pathway appears to be a crucial participant in the tenuous balance between effective pancreatic β-cell mass and insulin resistance.
Speciation by Distance in a Ring Species
Authors: Irwin Darren E. , Bensch Staffan , Irwin Jessica H. , Price Trevor D.
Published: January 2005

Ring species, which consist of two reproductively isolated forms connected by a chain of intergrading populations, have often been described as examples of speciation despite gene flow between populations, but this has never been demonstrated. We used amplified fragment length polymorphism (AFLP) markers to study gene flow in greenish warblers (
Phylloscopus trochiloides
). These genetic markers show distinct differences between two reproductively isolated forms but gradual change through the ring connecting these forms. These findings provide the strongest evidence yet for “speciation by force of distance” in the face of ongoing gene flow.
Mechanism of
hsp70i
Gene Bookmarking
Authors: Xing Hongyan , Wilkerson Donald C. , Mayhew Christopher N. , Lubert Eric J. , Skaggs Hollie S. , Goodson Michael L. , Hong Yiling , Park-Sarge Ok-Kyong , Sarge Kevin D.
Published: January 2005

In contrast to most genomic DNA in mitotic cells, the promoter regions of some genes, such as the stress-inducible
hsp70i
gene that codes for a heat shock protein, remain uncompacted, a phenomenon called bookmarking. Here we show that
hsp70i
bookmarking is mediated by a transcription factor called HSF2, which binds this promoter in mitotic cells, recruits protein phosphatase 2A, and interacts with the CAP-G subunit of the condensin enzyme to promote efficient dephosphorylation and inactivation of condensin complexes in the vicinity, thereby preventing compaction at this site. Blocking HSF2-mediated bookmarking by HSF2 RNA interference decreases
hsp70i
induction and survival of stressed cells in the G
1
phase, which demonstrates the biological importance of gene bookmarking.
For Many Approaches, Styles, and Aims
Authors: Bosch Xavier
Published: January 2005

Locating Medical History
The Stories and Their Meanings.
Frank Huisman and John Harley Warner, Eds.
. Johns Hopkins University Press, Baltimore, MD, 2004. 519 pp. $45, £32. ISBN 0-8018-7861-6.

The contributors provide a broad survey of the current diversity of approaches to the history of medicine.
DENSITY OF STATES FOR GUE THROUGH SUPERSYMMETRIC APPROACH
Authors: DISERTORI M.
Published: January 2005

The supersymmetric approach has proved to be a powerful tool for the study of random systems where classical techniques do not seem to apply. It also seems promising for rigorous analysis. In this context, we consider the GUE density of states, and show that, using the supersymmetric approach, we can rigorously re-derive the results obtained by classical techniques (orthogonal polynomials), in all energy regions (inside the spectrum, at the edge and outside the spectrum).
REVISITING THE CHARGE TRANSPORT IN QUANTUM HALL SYSTEMS
Authors: KOMA TOHRU
Published: January 2005

We re-examine the charge transport induced by a weak electric field in two-dimensional quantum Hall systems in a finite, periodic box at very low temperatures. Our model covers random vector and electrostatic potentials and electron–electron interactions. The resulting linear response coefficients consist of the time-independent term σxy corresponding to the Hall conductance and the linearly time-dependent term γsy · t in the transverse and longitudinal directions s=x,y in a slow switching limit for adiabatically applying the initial electric field. The latter terms γsy · t are due to the acceleration of the electrons by the uniform electric field in the finite and isolated system, and so the time-independent term σyy corresponding to the diagonal conductance which generates dissipation of heat always vanishes. The well-known topological argument yields the integral and fractional quantization of the averaged Hall conductance [Formula: see text] over gauge parameters under the assumption that there exists a spectral gap above the ground state. In addition to this fact, we show that the averaged acceleration coefficients [Formula: see text] vanish under the same assumption. In the non-interacting case, the spectral gap between the neighboring Landau levels persists if the vector and the electrostatic potentials together satisfy a certain condition, and then the Hall conductance σxy without averaging exhibits the exact integral quantization with the vanishing acceleration coefficients in the infinite volume limit. We also estimate their finite size corrections. In the interacting case, the averaged Hall conductance [Formula: see text] for a non-integer filling of the electrons is quantized to a fraction not equal to an integer under the assumption that the potentials satisfy certain conditions in addition to the gap assumption. We also discuss the relation between the fractional quantum Hall effect and the Atiyah–Singer index theorem for non-Abelian gauge fields.
ON THE CONVERGENCE OF COMPUTATIONAL AND DATA GRIDS
Authors: ARNOLD DORIAN C. , VAHDIYAR SATHISH S. , DONGARRA JACK J.
Published: January 2005

Great advances in high-performance computing have given rise to scientific applications that place large demands on software and hardware infrastructures for both computational and data services. With these trends the necessity has emerged for distributed systems developers that once distinguished between these elements to acknowledge that indeed computational and data services are tightly coupled and need to be addressed simultaneously. In this article, we compile and discuss several strategies and techniques, like co-scheduling and co-allocation of computational and data services, dynamic storage capabilities, and quality-of-service, that can be used to help resolve some of the aforementioned issues. We present our interactions with a distributed computing system, NetSolve, and a Distributed Storage Infrastructure, IBP, as a case study of how some of these techniques can be effectively deployed and offer experimental evidence from early prototypes that validate our motivation and direction.
NONDETERMINISM ANALYSIS ON SUPERCOMPUTERS AND CLUSTERS
Authors: KRANZLMÜLLER DIETER
Published: January 2005

Interconnecting computers into clusters or computational grids promises many benefits for users of computational science and engineering, especially in terms of performance and costs. This situation is additionally supported by programming libraries like MPI and PVM, which are portable across different platforms and allow to exploit the available computing power. Consequently, the number of applications utilizing these computing structures is steadily increasing. Yet, there are also some pitfalls with possibly serious consequences, that must not be ignored by software developers. This paper describes some critical issues related to nondeterministic program behavior. With such kinds of programs different program executions are observed although the same input data are provided, leading to the irreproducibility effect, the completeness problem, and the probe effect. The impact of these effects, their weight for software developers, and how they are affected on supercomputer architectures and cluster environments are discussed. These critical issues need to be pointed out to users in order to raise their understanding and awareness of the problems. While the irreproducibility effect is believed to be sufficiently solved by record&replay mechanisms, existing solutions for the probe effect are only partially successful, and only very few approaches address the completeness problem. A simple solution for the latter is offered by automatic event manipulation and artificial replay, which is however restricted by time and memory constraints. In addition, this solution to the completeness problem also solves the probe effect in nondeterministic parallel programs.
A NOTE ON COMMUNICATION-EFFICIENT DETERMINISTIC PARALLEL ALGORITHMS FOR PLANAR POINT LOCATION AND 2D VORONOÏ DIAGRAM
Authors: DIALLO MOHAMADOU , FERREIRA AFONSO , RAU-CHAPLIN ANDREW
Published: January 2005

In this note we describe deterministic parallel algorithms for planar point location and for building the Voronoï Diagram of n co-planar points. These algorithms are designed for BSP/CGM-like models of computation, where p processors, with [Formula: see text] local memory each, communicate through some arbitrary interconnection network. They are communication-efficient since they require, respectively, O(1) and O( log p) communication steps and [Formula: see text] local computation per step. Both algorithms require [Formula: see text] local memory.
AN IMPROVED PARALLEL ALGORITHM FOR DELAUNAY TRIANGULATION ON DISTRIBUTED MEMORY PARALLEL COMPUTERS
Authors: LEE SANGYOON , PARK CHAN-IK , PARK CHAN-MO
Published: January 2005

Delaunay triangulation has been much used in such applications as volume rendering, shape representation, terrain modeling and so on. The main disadvantage of Delaunay triangulation is large computation time required to obtain the triangulation on an input points sets. This time can be reduced by using more than one processor, and several parallel algorithms for Delaunay triangulation have been proposed. In this paper, we propose an improved parallel algorithm for Delaunay triangulation, which partitions the bounding convex region of the input points set into a number of regions by using Delaunay edges and generates Delaunay triangles in each region by applying an incremental construction approach. Partitioning by Delaunay edges makes it possible to eliminate merging step required for integrating subresults. It is shown from the experiments that the proposed algorithm has good load balance and is more efficient than Cignoni et al.'s algorithm and our previous algorithm.