bluuebunny/crossref_metadata_2025 huggingface dataset:
ATP stimulates MDM2‐mediated inhibition of the DNA‐binding function of E2F1
Authors: Stevens Craig , Pettersson Susanne , Wawrzynow Bartosz , Wallace Maura , Ball Kathryn , Zylicz Alicja , Hupp Ted R.
Published: August 2008

Murine double minute 2 (MDM2) protein exhibits many diverse biochemical functions on the tumour suppressor protein p53, including transcriptional suppression and E3 ubiquitin ligase activity. However, more recent data have shown that MDM2 can exhibit ATP‐dependent molecular chaperone activity and directly mediate folding of the p53 tetramer. Analysing the ATP‐dependent function of MDM2 will provide novel insights into the evolution and function of the protein. We have established a system to analyse the molecular chaperone function of MDM2 on another of its target proteins, the transcription factor E2F1. In the absence of ATP, MDM2 was able to catalyse inhibition of the DNA‐binding function of E2F1. However, the inhibition of E2F1 by MDM2 was stimulated by ATP, and mutation of the ATP‐binding domain of MDM2 (K454A) prevented the ATP‐stimulated inhibition of E2F1. Further, ATP stabilized the binding of E2F1 to MDM2 using conditions under which ATP destabilized the MDM2:p53 complex. However, the ATP‐binding mutant of MDM2 was as active as an E3 ubiquitin ligase on E2F1 and p53, highlighting a specific function for the ATP‐binding domain of MDM2 in altering substrate protein folding. Antibodies to three distinct domains of MDM2 neutralized its activity, showing that inhibition of E2F1 is MDM2‐dependent and that multiple domains of MDM2 are involved in E2F1 inhibition. Dimethylsulfoxide, which reduces protein unfolding, also prevented E2F1 inhibition by MDM2. These data support a role for the ATP‐binding domain in altering the protein–protein interaction function of MDM2.
Relationships between soil microbial diversity and plant community structure in seminatural grasslands
Authors: Sugiyama Shu‐ichi , Zabed Hossain M. , Okubo Atsushi
Published: August 2008

Although plants and soil biota have mutual functional links as producers and decomposers in terrestrial ecosystems, less is known about structural linkages between above‐ground and below‐ground communities. For this study, we examined whether plant species richness and soil microbial richness are related to each other, and how their richness is related to soil fertility and herbivore activity at 24 plots of the Shiriyazaki seminatural grassland in northern Japan. Prokaryote (bacterial) richness and eukaryote richness were evaluated by the band number of denaturing gradient gel electrophoresis (DGGE) using 16S and 18S ribosomal DNA fragments. Plant species richness was negatively related to soil nitrogen availability and phosphorus content. Prokaryote richness showed a negative correlation with soil phosphorus contents and no significant correlation with vegetation structure (height, richness and functional type composition). Eukaryote (mainly fungi) richness showed significant positive correlations with plant species richness, community height and forb species composition. These results suggest that bacterial richness is influenced by soil properties, whereas eukaryote richness is associated closely with vegetation structure.
Friction of a C/SiC Composite Bearing in Air and in Combustion Environments
Authors: Zhang Yani , Zhang Litong , Cheng Laifei , Luan Xingang , Chen Bo , Liu Chidong
Published: August 2008

A bearing used for the load‐carrying hinge was manufactured based on a carbon fiber‐reinforced silicon carbide matrix (C/SiC) composite with a SiC coating. Chemical vapor infiltration was applied in the process of the composites. Experiments were conducted by an experimental simulation method that would facilitate testing under coupling stress in air and in combustion environments. Modeling analysis deduced the relationship of applied load, normal contact force, and friction force in the hinge bearing. Friction behavior was comparatively investigated up to 10 kN at room temperature in air and at 1800°C in combustion environments. Worn surfaces were observed by scanning electron microscopy, and surface roughness was measured by atomic force microscopy. Reliable thermal load‐carrying ability and stable friction performance of the hinge bearing are demonstrated under this testing framework. The oxide products in the combustion environment play an important role in reducing friction by providing a reaction layer to moderate the contact stresses.
On the detection of internal gravity waves in the solar photosphere
Authors: Stodilka M. I.
Published: August 2008

The distribution of temperature perturbations over the solar photosphere was reconstructed. The k - ω and phase filtering was applied to Fourier image of space–time variations of temperature in order to find the signatures of local internal gravity waves. Within the convectively stable photospheric layers, the structures have been identified featuring the following properties: quasi-periodicity in space (at scales of mesogranulation) and time, mostly horizontal propagation with subsonic velocities, the group velocity of and the wavepacket perpendicular to its phase velocity. Such properties are exactly those of internal gravity waves.
Chromatin – a New, Old Drug Target?
Authors: Davey Gabriela E. , Davey Curt A.
Published: August 2008

Chromatin is the therapeutic target for DNA‐binding medicinal agents, yet we know substantially more about the interaction of drugs with naked DNA. Current research is unraveling a dynamic gene‐ and transcription state‐dependent structure for human chromatin and also unveiling differences in nucleosome positioning between cancer and normal cells. Considering observations on the modulation of DNA drug binding and adduct repair by histone packaging suggests potential for targeting specific sites within nucleosomes that coincide with weak points of cancer cells.
Database Ethnographies Using Social Science Methodologies to Enhance Data Analysis and Interpretation
Authors: Schuurman Nadine
Published: August 2008

Data are the basis for many decisions ranging from assessing credit applications, to determining societal risk of criminals to adjudicating grant applications. Data collection and use constitute social practices, yet once data are placed in tables, their social lineage is forgotten. Database ethnographies are a unique means of using insights from science and technology studies and practices from the social sciences to enhance data analysis. The goal of this methodology is to elicit information from data stewards about the data in multiple‐use databases in order to provide an archive that describes the context and meaning of the data at a particular point in time. This article provides a review of a composite literature that contributed to the concept and implementation of database ethnographies. In addition, it illustrates how database ethnographies contribute to more nuanced metadata and act as the basis for informed decision‐making involving data from multiple sources.
Time‐course Expression of DNA Repair‐related Genes in Hepatocytes of Zebrafish (Danio rerio) After UV‐B Exposure
Authors: Sandrini Juliana Z. , Trindade Gilma S. , Nery Luiz Eduardo M. , Marins Luis F.
Published: August 2008

The objective of this study was to evaluate the time‐course effects of UV‐B exposure on expression of genes involved in the DNA repair system of zebrafish (Danio rerio) hepatocytes, a highly competent species in terms of damage repair induced by UV radiation. For gene expression analysis (RT‐PCR), cells were exposed to 23.3 mJ cm−2 UV‐B, which was the dose that affected viable cell number (reduction of 30% when compared with the control group) and produced no visual alteration on cell morphology. The early response observed (6 h) showed induction in the expression of the CDKI gene (cyclin‐dependent kinase inhibitor) and genes related to DNA damage repair (mainly XPC and DDB2), while the late response observed (24 h) was more related to up‐regulation of p53 and genes involved in cell cycle arrest (gadd45a, cyclinG1). In all times analyzed, the anti‐apoptotic gene Bcl‐2 was down‐regulated. Another interesting result observed was the up‐regulation of the Apex‐1 gene after UV‐B exposure, which could indicate the induction of oxidative lesions in the DNA molecule. In conclusion, these results demonstrate an activation of the DNA repair system in hepatocytes of zebrafish exposed to UV‐B radiation, mainly involving the participation of p53.
Monitoring the Accumulation of Lipofuscin in Aging Murine Eyes by Fluorescence Spectroscopy
Authors: Mukherjee Prasun , Bose Sayantan , Hurd Alyse A. , Adhikary Ramkrishna , Schönenbrücher Holger , Hamir Amir N. , Richt Jürgen A. , Casey Thomas A. , Rasmussen Mark A. , Petrich Jacob W.
Published: August 2008

The integrated fluorescence of murine eyes is collected as a function of age. This fluorescence is attributed to pigments generally referred to as lipofuscin and is observed to increase with age. No difference in fluorescence intensity is observed between the eyes of males or females. This work provides a benchmark for further studies that are planned in order to use such signatures as markers of central nervous system (CNS) tissue or even of diseased CNS tissue and provides a basis for determining the age of a healthy animal.
The Photoreactions of Recombinant Phytochrome CphA from the Cyanobacterium Calothrix PCC7601: A Low‐Temperature UV–Vis and FTIR Study
Authors: Schwinté Pascale , Gärtner Wolfgang , Sharda Shivani , Mroginski Maria‐Andrea , Hildebrandt Peter , Siebert Friedrich
Published: August 2008

The photoreactions of recombinant phytochrome CphA from cyanobacterium Calothrix sp. PCC7601 reconstituted with phycocyanobilin were investigated using UV–Vis and Fourier transform infrared (FTIR) difference spectroscopy, stabilizing intermediates at low temperature. The yield of the forward reaction strongly depends on temperature, unlike the backward reaction. Because of the very fast thermal relaxation processes in the Pr to Pfr pathway, no pure difference spectra of the Pr photoconversion products could be directly measured. Thus, the contribution of the Pfr:Pr pathway was taken into account by applying an appropriate correction procedure both in the UV–Vis and FTIR experiments. Three intermediates have been trapped at −25, −45 and −120°C, which show the characteristic vibrational band pattern of the plant phytochrome phyA intermediates meta‐Rc, meta‐Ra and lumi‐R, respectively. In the backward reaction, two intermediates corresponding to meta‐F and lumi‐F were trapped at −70 and −140°C, respectively. FTIR spectra of all intermediates, as well as of the Pfr state, show remarkable similarities with the corresponding spectra of Cph1 phytochrome from cyanobacterium Synechocystis and the 59 kDa N‐terminal fragment of Cph1, and, albeit not so pronounced, also with plant phyA. The spectral similarities and differences between the various phytochromes are discussed in terms of structural changes of the chromophore and the chromophore–protein interactions.
Sensitivity ofStaphylococcus aureusStrains to Broadband Visible Light
Authors: Lipovsky Anat , Nitzan Yeshayahu , Friedmann Harry , Lubart Rachel
Published: August 2008

The phototoxic effect of illumination with broadband visible light on the viability of twoStaphylococcus aureusstrains was examined in the present study. A difference in the light sensitivity of the two strains was found. Illumination of the tested strains with a fluence rate of 180 J cm−2caused a reduction of up to 99.8% in the colony count of one of the strains (the “sensitive” strain). Illumination of the other strain (the “resistant” strain) resulted in a 55.5% reduction in viability. Proliferation of both strains was observed at low fluence rates of light. The phototoxic effect was found to be dependent on oxy radical production. The light‐sensitive strain produced higher amounts of hydroxyl and superoxide radicals than the “resistant” strain. Adaptation to oxidative stress was exhibited only by the “resistant” strain. The “sensitive” strain produced ten times more endogenous porphyrins and secreted almost nine times more porphyrins than the resistant strain. Furthermore, the “resistant” strain produced twice as many carotenoids that protect the strain from illumination than the “sensitive” strain. These results indicate that high intensities of visible light cause bacterial photoeradication, a reaction which may assist wound healing by killing the infecting bacteria. On the other hand, low intensities of white light were found to enhance bacterial proliferation and thus prolong wound infection.
Sensitivity of Erythemally Effective UV Irradiance and Daily Exposure to Temporal Variability in Total Ozone
Authors: Schmalwieser Alois W. , Erbertseder Thilo , Schauberger Günther , Weihs Philipp
Published: August 2008

The provision of information to the public about current levels of the erythemally effective UV radiation is an important issue in health care. The quality of promoted values is therefore of special importance. The atmospheric parameter which affects the erythemally effective UV radiation under clear sky most is the total ozone content of the atmosphere. In this paper we examined the sensitivity of the erythemally effective irradiance and daily radiant exposure to the temporal variability of total ozone on time scales from 1 to 15 days. The results show that the sensitivity is highest for the first 24 h. Larger time scales do not exhibit a similar influence. Total ozone measurements of the previous day may already cause uncertainties higher than 0.5 UV index (UVI) independent of the geolocation. For comparison, a temporal persistence of 15 days may cause uncertainties of 1.2 UVI at 50°N, 1 UVI at 30°S and less than 1 UVI at the equator. The results of this study allow finding the necessary temporal resolution of total ozone values when a certain accuracy for the UVI or for the purpose of sun protection is required. The results are compared with those of two preceding studies where we quantified the influence of measurement uncertainties and spatial total ozone variability to the erythemally effective irradiance at noon and to the daily dose. We conclude that temporal variability of total ozone is the most critical issue, but also measurement uncertainties do have a noticeable influence on the erythemally effective radiation.
Smoking Cessation Interventions and Older Adults
Authors: Doolan Daniel M. , Froelicher Erika Sivarajan
Published: August 2008

Older adults suffer a large proportion of the health consequences from smoking and can greatly benefit their health by quitting smoking. This article examines the current state of research and practice for older adults and smoking cessation interventions. For over 17 years, the health care literature has mandated that people of all ages be provided with smoking cessation interventions. However, smoking cessation interventions are offered to older adults at suboptimal rates. Nurses, especially those caring for clients in the inpatient setting, have an opportunity to provide smoking cessation interventions to older smokers. Recent research has shown that older smokers, particularly those hospitalized with cardiovascular disease, can quit at high rates when provided an intervention. Furthermore, use of nicotine replacement therapy has been shown to be safe and efficacious among older smokers with cardiovascular disease.
Isolation and characterization of 12 polymorphic microsatellite markers in the tropical house gecko (Hemidactylus mabouia)
Authors: SHORT KRISTEN HARFMANN , PETREN KENNETH
Published: August 2008

We present 12 variable microsatellite loci isolated from the invasive tropical house gecko, Hemidactylus mabouia. Polymerase chain reaction (PCR) primers were tested on 39 individuals from two locations in Miami, Florida. Heterozygote deficiency was detected for four loci, and we attribute this to possible null alleles or population substructure. Some loci successfully amplified PCR products in several congeners, indicating their potential for use in other geckos.
Polymorphic microsatellite DNA markers for Daviesia triflora (Papilionaceae)
Authors: HE TIANHUA , KRAUSS SIEGFRIED L. , LAMONT BYRON B.
Published: August 2008

We developed 11 polymorphic microsatellite DNA markers for an Australian native plant, Daviesia triflora. The number of alleles per locus in 40 individuals varied from four to 19, and observed and expected heterozygosities ranged from 0.450 to 0.925 and from 0.497 to 0.899, respectively. Nine loci showed no significant deviation from Hardy–Weinberg equilibrium (P > 0.05), and null alleles appear to exist at loci DT‐A102 and DT‐B103. All loci showed independent inheritance.
Amplification of rainbow trout microsatellites in Brachymystax lenok
Authors: JIA Z. Y. , ZHANG Y. Y. , SHI L. Y. , BAI Q. L. , JIN S. B. , MOU Z. B.
Published: August 2008

Brachymystax lenok is a cold freshwater fish accustomed to inhabit relatively high concentration of dissolved oxygen and clean upper streams. Here we present 13 polymorphic microsatellite primer pairs from rainbow trout to amplify in 32 B. lenok individuals from Ussuri River of China. The number of alleles ranged from two to seven with an average of 3.9 per locus. Observed heterozygosity ranged from 0.0625 to 0.9677. One locus showed significant deviation from Hardy–Weinberg equilibrium. These 13 loci will provide a good basis for investigation of B. lenok population structure and genetic diversity in different distribution region.
Bone marrow necrosis and myelophthisis: manifestations of T‐cell lymphoma in a horse
Authors: Kelton Danielle R. , Holbrook Todd C. , Gilliam Lyndi L. , Rizzi Theresa E. , Brosnahan Margaret M. , Confer Anthony W.
Published: August 2008

Abstract:A 14‐year‐old spayed American Paint mare was evaluated for mild colic, anorexia, pyrexia, and pancytopenia. Physical examination revealed mild tachycardia, tachypnea, and pale mucous membranes. Serial laboratory analyses revealed progressive pancytopenia, hyperfibrinogenemia, and hyperglobulinemia. A few large atypical cells were observed in peripheral blood smears. Results of tests for equine infectious anemia and antipenicillin antibody were negative. Serum protein electrophoresis indicated a polyclonal gammopathy. Smears of bone marrow aspirates contained hypercellular particles, but cell lines could not be identified because the cells were karyolytic, with pale basophilic smudged nuclei and lack of cellular detail. A diagnosis of bone marrow necrosis was made. Treatment consisted of antimicrobials, nonsteroidal anti‐inflammatory drugs, and corticosteroids. The pyrexia resolved; however, the pancytopenia progressively worsened and petechiation and epistaxis developed. The horse was humanely euthanized. Postmortem examination revealed a diffuse round cell neoplasm infiltrating the kidneys, spleen, lymph nodes, lungs, and bone marrow. Immunophenotyping results (CD3+, CD79α−) indicated the neoplastic cells were of T‐cell lineage. Infiltration of lymphoma cells into the bone marrow appeared to have resulted in severe myelophthisis and bone marrow necrosis. Bone marrow necrosis has been associated previously with lymphoma in humans and dogs. To our knowledge, this is the first reported case of lymphoma resulting in bone marrow necrosis in a horse.
Assessment of serum protein fractions in rainbow trout using automated electrophoresis and densitometry
Authors: Manera M. , Britti D.
Published: August 2008

Background: Although rainbow trout (Oncorhynchus mykiss, Walbaum) are one of the most‐studied fish, electrophoretic techniques and classification of serum protein fractions have not been standardized, such that clinically useful values are lacking.

Objective: The aim of the present study was to evaluate preliminarily the serum protein fractions of rainbow trout using automated cellulose acetate electrophoresis and densitometry.

Methods: Serum samples from 25 rainbow trout (Oncorhynchus mykiss, Walbaum) were electrophoresed on cellulose acetate plates and quantified using densitometry.

Results: A maximum of 6 fractions were identified and numbered, in order of decreasing mobility, as I, II, III, IV, V, and VI. In 3 of 25 (12%) samples, 6 fractions were identified; in 18 (72%) samples, 5 fractions were identified; and in 4 (16%) samples, 4 fractions were identified. Fractions I, V, and VI were always clearly identifiable, whereas fractions II and IV were frequently fused and indistinguishable from fraction III. The pattern with 5 fractions was the most probable type (χ2, P<.01). The mean (±SEM) protein concentrations of the 6 fractions were I, 0.8±0.1 g/dL; II, 0.3±0.0 g/dL; III, 1.6±0.1 g/dL; IV, 0.3±0.1 g/dL; V, 0.6±0.0 g/dL; and VI, 0.2±0.0 g/dL. Based on comparison of serum and plasma electrophoretic patterns from 8 fish, fibrinogen was found in fraction V.

Conclusion: Automated cellulose acetate electrophoresis and densitometry appear to be a practical method for estimation of serum protein fractions in rainbow trout.
Decreased exercise blood pressure in older adults after exercise training: contributions of increased fitness and decreased fatness
Authors: Barone B B , Wang N-Y , Bacher A C , Stewart K J
Published: August 2008

Objective:

To describe the contribution of changes in fitness and fatness resulting from exercise training on changes in submaximal exercise blood pressure (BP) during treadmill testing.

Design and setting:

Prospective, randomised, controlled trial.

Participants:

Sedentary older adults (n = 115) with untreated prehypertension or mild hypertension.

Intervention:

Six-month supervised aerobic and strength training.

Main outcome measurement:

Systolic BP (SBP) was assessed at rest and during each stage of a maximal graded exercise test (GXT) that determined Vo2peak. General and regional fatness was assessed by anthropometry, dual-energyx-ray absorptiometry and MRI. BP changes were calculated for each GXT stage, and multivariate regression models were used to describe the association of changes in exercise BP with changes in fitness and fatness.

Results:

After training, exercisers versus controls had significantly increased Vo2peak and significantly lower measures of general and regional fatness. Also, stage-specific SBP was significantly lower at stage 3 (−9.4 vs −1.6 mm Hg, p = 0.03) and stage 4 (−7.9 vs −1.2 mm Hg, p = 0.03). Pooled regression analysis across all stages showed that exercisers had a 7.1 mm Hg reduction in SBP, but this reduction fell short of statistical significance (p = 0.12) compared with controls. A 1.0 ml/kg/min increase in Vo2peak and a 1.0 cm decrease in waist circumference independently predicted a 1.0 mm Hg decrease in exercise SBP (p = 0.04 and p = 0.001, respectively).

Conclusions:

Decreased exercise SBP was independently associated with decreased waist circumference, a marker of abdominal obesity and increased fitness. These findings suggest that exercise training improves multiple factors that have an independent influence on SBP.
Efficiency of Large-Volume Plankton Pumps, and Evaluation of a Design Suitable for Deployment from Small Boats
Authors: Taggart Christopher T. , Leggett William C.
Published: August 2008

A critical review of previously published studies, and evaluation of a newly developed pump system, showed the often stated shortcomings of large-volume pumps as instruments for sampling plankton communities (e.g. damage to organisms sampled, volumes too small to estimate plankton density accurately, and systems too cumbersome to handle) to be invalid. Previously published estimates of the comparative efficiency of large-volume pump samplers and tow nets should; however, be viewed with caution because the techniques used to estimate pumped volume are error prone. In-line flow meters are essential for accurate volume estimation. Comparative efficiency tests of a newly developed large-volume pumping system deployed simultaneously with 80- and 153-μm mesh standard plankton nets revealed that the pump, while sampling only 8% of the volume sampled by the nets, was equally effective in capturing capelin (Mallotus villosus) larvae (5-mm length), herring (Clupea harengus) larvae (9-mm length), large copepods (> 750 μm), small jellyfish, and hyperiid amphipods. The pump was superior to nets in sampling crab zoea and megalops larvae and becomes more efficient at capturing euphausiids and chaetognaths as their natural densities increase. Nets were superior in the capture of fish eggs (primarily cunner, Tautogolabrus adspersus), possibly due to the vertical distribution of eggs in the water column. The average length of capelin larvae captured by pumping was consistently 0.2 mm longer than that of larvae taken in nets, but the length–frequency distribution of larvae sampled was similar to that of larvae entering the pelagic environment. Attaching the pump intake to the cod-end of a rigid tow net is suggested as a method of surmounting potential errors when sampling organisms at densities below 1–5/m3.
Inorganic Nitrogen Uptake in Oligotrophic Lake Taupo, New Zealand
Authors: Priscu John C. , Priscu Linda R.
Published: August 2008

To determine nitrogen and carbon uptake in the surface waters of oligotrophic Lake Taupo, New Zealand, we used isotope tracer methods. Time-course measurements of NH4+ and NO3− uptake at near saturating concentration revealed about a fourfold greater uptake during the first hour of incubation relative to averaged 1–6 h uptake rates. This enhanced uptake was most apparent during the first 5–10 min of incubation. Uptake kinetics experiments indicated that the N assimilation rate was generally limited by low ambient concentrations of inorganic N. The half-saturation constants for N uptake were low [Formula: see text] and comparable with ambient levels of NH4+ and NO3−; NO3− uptake was always lower than NH4+ uptake and was inhibited strongly (~60%) in the presence of ~5 μg NH4+-N∙L−1. Carbon to N uptake ratios averaged (±SD) 20.9 ± 11.7 (grams C to grams N) and were correlated with seston compositional ratios. Polysaccharide was the major end product of photosynthesis (as measured by 14C incorporation) in measurements made at 100 μE∙m−2∙s−1 whereas protein was the primary end product during dark incubations. Samples enriched with NH4+ and incubated at 100 μE∙m−2∙s−1 showed a significant increase in the 14C incorporated into protein, at the expense of that incorporated into polysaccharide and low molecular weight metabolites. No differences in the pathway of C flow were observed in NH4+-enriched, dark-incubated samples. Nitrogen uptake estimates based on the percent of 14C in the protein fraction were similar to those calculated by the 15N technique.
Relationships between the Partitioning of Trace Metals in Sediments and Their Accumulation in the Tissues of the Freshwater Mollusc Elliptio complanata in a Mining Area
Authors: Tessier A. , Campbell P. G. C. , Auclair J. C. , Bisson M.
Published: August 2008

Surficial sediment samples and specimens of a benthic freshwater pelecypod, Elliptio complanata, were collected at eight sites located along a metal contamination gradient downstream from the mining and smelting complex in Rouyn–Noranda, Quebec. The molluscs were dissected, digested, and analysed for Cu, Pb, Zn, Fe, and Mn by flame atomic absorption spectrophotometry. Each sediment sample was wet sieved and the < 70-μm granulometric fraction was subjected to a sequential extraction procedure designed to determine the partitioning of the trace metals among various geochemical phases. Regression analysis indicates that Cu, Pb, and Zn levels in various tissues of E. complanata (or in the whole organism, without the shell) are best related, not to total metal concentrations in the adjacent sediment, but rather to one or more of the relatively easily extracted fractions. Accumulation of Cu, Pb, and Zn was also influenced by the protective or competitive effect of other sediment constituents, notably amorphous iron oxyhydroxides and, to a lesser degree, organic matter.
Comparison of N,N-Dimethylformamide, Dimethyl Sulfoxide, and Acetone for Extraction of Phytoplankton Chlorophyll
Authors: Speziale Barbara J. , Schreiner Stephen P. , Giammatteo Paul A. , Schindler James E.
Published: August 2008

We evaluated the suitability of N,N-dimethylformamide (DMF) for extraction and measurement of chlorophyll in phytoplankton and compared the extraction efficiencies of DMF, dimethyl sulfoxide (DMSO)–acetone, and 90% acetone. Absorbance spectra and specific absorption coefficients of chlorophylls a, b, and c in DMF and 90% acetone are similar. Acidification of 100% DMF extracts of pure chlorophyll a and healthy algal cultures produced acid ratios approximating 1.7. Thus, equations derived from the extinction coefficients of chlorophylls in 90% acetone can be applied to DMF extracts. DMF and DMSO–acetone each extract chlorophyll from green and blue-green algae more effectively than does 90% acetone. DMF is a better extractant than is DMSO–acetone for chlorococcalean species, especially when pigment concentrations are high, but the difference, although significant, is slight. The three solvents are equally efficient in extracting chlorophyll from samples composed of chrysophytes and flagellated chlorophytes. The lack of grinding when using either DMF or DMSO–acetone is a considerable convenience. The potential for destabilized spectrophotometer readings and contamination of the investigator due to the incomplete mixing of DMSO and acetone is eliminated when pure DMF is used.
Need for Development of Epidemiology for Chemically Induced Diseases in Fish in Canada
Authors: Gilbertson Michael
Published: August 2008

There are few case histories in Canada in which chronic low level exposure to pollutants has been demonstrated to have caused deleterious effects on fish. I challenge the adequacy of approaching aquatic toxicology mainly by laboratory experimentation. I argue that the discipline should start from observations of anomalous biological phenomena in the environment.
Cytogenetic determination of sex among individually identified humpback whales (Megaptera novaeangliae)
Authors: Lambertsen Richard H. , Baker C. Scott , Duffield Deborah A. , Chamberlin-Lea Jan
Published: August 2008

Using a small biopsy dart, samples of living dermal tissue were collected from individually identified humpback whales (Megaptera novaeangliae) in southeastern Alaskan waters. In vitro culture of these samples provided enough chromosomal material to karyotype 10 individuals. Examination of the sex chromosomes in the karyotypes demonstrated the sex of each of the 10 whales. In two cases, cytogenetic findings verified previous inferences of sex based on behavioral observations. In another two cases, karyotyping allowed the determination of sex when even long-term sighting histories and behavioral observations had been insufficient. For the rest of the whales, sex determination by cytogenetic findings has preceded long-term sightings and will facilitate the interpretation of future behavioral observations. We conclude that in vitro culturing of dermal tissue collected from naturally marked humpback whales, coupled with karyology, promises to be a powerful technique in future studies of the social behavior and population biology of this marine species.
Wolf movements and population dynamics in Papineau-Labelle reserve, Quebec
Authors: Potvin François
Published: August 2008

From 1980 to 1984, wolf ecology was studied in Papineau-Labelle reserve, a 1667-km2 area characterized by three large deer yards (> 1000 deer) located at the periphery. We obtained 2462 telementry locations from 43 collared wolves belonging to 4–8 packs. Mean pack size on 1 December was 5.6 wolves and density within territories averaged 2.8 animals/100 km2. Size of territories ranged between 85 and 325 km2 (mean 199 km2) and no seasonal variations were noted for most packs. But those packs in contact with a large deer yard generally used that portion of their territory more intensely in winter. The majority of wolves (12/15) dispersed when they were 10–20 months old and traveled an average distance of 40 km. Dispersal likely resulted from the onset of sexual maturity and, possibly, from social stress. Mortality rate of collared wolves (36%) was moderate and similar to that of noncollared wolves. Known causes of mortality were all human related: trapping (23), hunting (6), and road kills (6). Nonetheless, I conclude that this population is regulated largely by social factors and not by food stress.
Wolf diet and prey selectivity during two periods for deer in Quebec: decline versus expansion
Authors: Potvin François , Jolicoeur Hélène , Huot Jean
Published: August 2008

We compare wolf diet and prey selectivity for two periods: 1974–1976, when deer were at low density (< 0.4/km2) and had even disappeared locally, and 1980–1984, when they became fairly abundant (about 3/km2). A total of 1166 wolf scats were analysed and the remains of 296 deer killed by predation were found. Although moose were present in both areas, wolves fed primarily on deer in winter even when this prey species had almost disappeared locally. In summer, moose and beaver made up more than 75% of the wolf diet, irrespective of deer density. Wolves preyed mainly on prime-age deer in periods of scarcity, but selected fawns and older animals when deer became more abundant. Under these conditions, wolf predation can have "antiregulatory" effects on deer populations.
The feeding behavior of a polyphagous caterpillar (Diacrisia virginica) in its natural habitat
Authors: Dethier V. G.
Published: August 2008

The ground-dwelling woolly bear caterpillar Diacrisia virginica occupies a habitat characterized by low-lying forbs, grasses, and sedges where it feeds on more than 100 species of plants. The short effective range of its visual and olfactory senses restricts to 1 cm or less the distance from which it can recognize plants. Caterpillars meander randomly and blunder into food plants. Because of the dense and complex vegetational texture of the habitat, the random locomotion in the field, and the omnivorous diet of the caterpillars, only a small proportion of time need be spent wandering (2%). More than 90% of the time is devoted to inactivity which represents postprandial and trail resting. Meal size is regulated by state of deprivation and is modified by the position of the plant in the hierarchy of acceptability. With increasing deprivation larvae become less finicky and therefore seldom experience acute starvation. The effectiveness of plants in sustaining survival and optimal growth of caterpillars is only grossly correlated with acceptability. The field behavior of D. virginica seems to be well described by the thermostatic model of feeding which predicts time budgeting for animals as a function of physiological and ecological parameters.
Eye color pigment granules in wild-type and mutant Drosophila melanogaster
Authors: Stark William S. , Sapp Randall
Published: August 2008

Eye color pigment granules were studied in ultrathin sections of the wild-type fruit fly Drosophila melanogaster and the following eye-color mutants, cinnabar (cn), brown (bw), cinnabar brown (cn bw), and white (w). Ommatin-containing granules of the primary pigment cells are electron lucent in newly emerged flies but are dense in aged flies. The intraretinular granules are of intermediate or high electron density and also contain ommatins. The content of these granules was deduced from comparisons between wild type and cn, which blocks ommatin synthesis. The bw mutant was used to show that drosopterins reside throughout the secondary pigment cells while drosopterin granules monopolize the distal portion. The secondary pigment cell's granules, especially the most distal ones, are electron lucent in our work as well as in most earlier publications. Here we show that these granules are manifested as holes in the section. Both ommatins and drosopterins reside more proximally in the compound eye's pigment cells. We show that white-eyed flies have unusually large granules, and the possible function of these structures is discussed.
Quantitative analysis of feeding kinematics in dusky salamanders (Desmognathus)
Authors: Larsen Jr. John H. , Beneski Jr. John T.
Published: August 2008

Gape formation by the dusky salamander (Desmognathus) involves both upper and lower jaws and occurs in a manner similar to that of other terrestrial salamanders. As Desmognathus opens its mouth, ventral rotation of the mandibles is restricted but not stopped by the atlas–mandibular ligaments; the lower jaw is not propelled anteriorly. Tongue protraction, well beyond the mandibular symphysis, is always a major component of prey capture by this genus. After the sticky tongue pad has made contact with the prey, the salamander's head surges forward and the pad is rapidly retracted with the prey item attached. Aided by a unique suite of characters the mouth then snaps shut with considerable force. Our study supports the premise that Desmognathus is no different from most, if not all, terrestrial salamanders in its employment of tongue projection as a major feature in prey capture. We argue that the primary selective force for the unique configuration of desmognathine cephalic structures was enhancement of the ability of these small salamanders to capture relatively large prey without an increase in the size of the head and body.
Gonatothrix carinata, a new genus and species of the family Macrochelidae (Acari: Gamasida) phoretic on Phanaeus pyrois Bates (Coleoptera: Scarabaeidae)
Authors: Krantz G. W.
Published: August 2008

A new genus is proposed to accommodate an unusual new species, Gonatothrix carinata, of the mite family Macrochelidae phoretic on the scarab beeetle Phanaeus pyrois. The new genus is distinguished by strong opisthosomatic hypertrichy, a strongly narrowed opisthonotal component of the dorsal shield, singular sternal shield ornamentation, and the presence of eight setae on genu III.
Dive times and ventilation patterns of singing humpback whales (Megaptera novaeangliae)
Authors: Chu Kevin C.
Published: August 2008

The dive times and ventilation rates of individual singing humpback whales (Megaptera novaeangliae) on Silver Bank, Dominican Republic, are compared. All singers in this study were alone and moving slowly, so the behavioral states of the whales were imilar. For individual whales, longer dives are clearly followed by more exahalations. Therefore, the longer a singer holds his breath, the greater the need to breathe must be. However, some singers dived for longer periods than did others, and singers with longer mean dive times did not necessarily breathe more often upon surfacing than did singers with short dives. Long dives, then, appear to be less stressful for some whales than for others. The data suggest that some singers are in better physical condition than others. I speculate that by singing, a male humpback may be conveying information about his diving ability and general physical condition.
Sexual dimorphism in size and plumage of the polyandrous Dotterel (Charadrius morinellus): sex roles and constraints on sexual selection
Authors: Kålås John Atle
Published: August 2008

Data on live birds and previously published data reveal that female Dotterel (Charadrius morinellus) were on average larger than males for all measurements. However, sexual dimorphism on the basis of size appears weaker than expected when Dotterel are compared with closely related monogamous species. Female museum specimens have less disrupted (brighter) plumage colours than males, and dimorphism in plumage is more pronounced than it is in size. A discriminant analysis based on plumage characters did not separate the sexes totally, however. Females moult earlier in the spring than males, but summer plumage is still not fully developed for all females by the first period of pair formation, suggesting that female plumage is most important in reproduction only after the first clutch is complete. No significant differences were evident in wing length and plumage colour between 1882–1917 and 1957–1982. Time–activity studies on the polyandrous Dotterel during the arrival, prelaying, and egg-laying periods showed small differences between the sexes in the amount of time devoted to agonistic and courtship behaviour. Data from prelaying periods showed no difference between the sexes as to who initiates bouts of courtship and agonistic behaviour. The behaviour of paired birds was highly synchronized. Three hypotheses on the slight sexual dimorphism in size and plumage of this polyandrous species are presented and discussed.
The effect of plumage color on the thermoregulatory abilities of Lesser Snow Goose goslings
Authors: Beasley Barbara A. , Ankney C. Davison
Published: August 2008

A comparison of the reflectance spectra of Lesser Snow Goose (Chen caerulescens caerulescens) goslings revealed that dark-colored goslings (blues) absorbed more visible and near infrared radiation than did light-colored goslings (snows). Thus, we predicted that blues would obtain greater radiative heat loads and expend less energy to thermoregulate in cold, sunny weather but that radiation would be transmitted deeper into light-colored plumages giving snows a thermal advantage under windy conditions. Using doubly labeled water with penned birds at the La Pérouse Bay colony, we found no significant difference in the daily energy expenditures of blues and snows. Blues tended to expend more energy on windy, sunny days and less on calm, cloudy days but the trends were nonsignificant. We conclude that color has a negligible influence on the energy budgets of Lesser Snow Goose goslings relative to the effect of behavioral thermoregulation.
Developmental success of hybrids between two taxa of salmonid fishes with moderate structural gene divergence
Authors: Ferguson Moira M. , Danzmann Roy G. , Allendorf Fred W.
Published: August 2008

The developmental rate and stability of Yellowstone cutthroat trout (Salmo clarki bouvieri) (Y), westslope cutthroat trout (Salmo clarki lewisi) (W), and their hybrids (female × male) were used to examine the evolutionary divergence of gene regulatory systems between these taxa. The Nei's structural gene divergence between these subspecies has been estimated as D = 0.34. Pure W × W developed significantly faster than Y × Y as detected by hatching time and degree of yolk sac resorption. In addition, W × W embryos had greater activities of malate dehydrogenase, lactate dehydrogenase, phosphoglucomutase, and glucose-6-phosphate isomerase from hatching to yolk sac resorption than Y × Y embryos. The two hybrids did not differ significantly from their maternal parental cross in hatching time. W × Y hybrids did, however, hatch significantly sooner than Y × W hybrids. There were no consistent differences between the parental crosses and hybrids in the amount and rate of increase in activity of the four enzymes. Hybrids had significantly greater meristic counts for two out of four characters than the parental crosses. Heterotic effects were observed in that hybrids were longer and showed a faster rate of yolk sac resorption than their maternal parental cross. Moreover, the Y × W hybrid had significantly greater developmental stability as measured by fluctuating asymmetry of four bilateral meristic characters than the Y × Y cross. The lack of perturbation in the development of hybrids indicates that despite their structural gene divergence, few gene regulatory incompatibilities affecting the developmental process exist between these cutthroat trout taxa.
Malnutrition during the postnuptial molt of White-crowned Sparrows: feather growth and quality
Authors: Murphy Mary E. , King James R. , Lu Jianjian
Published: August 2008

It has often been alleged that avian molt can be interrupted or delayed by food deprivation or malnutrition. We examined this experimentally in captive White-crowned Sparrows (Zonotrichia leucophrys gambelii). Beginning either at the natural onset of postnuptial molt or 1 month before its onset, groups of birds were fed either inadequate amounts of a balanced diet (60 or 80% of the ad libitum intake of a control group) or unlimited amounts of a diet deficient only in cyst(e)ine and methionine. Except in the 60% premolt group, the malnourished birds did not postpone or interrupt molt in spite of losses ranging from 20 to 38% of initial body mass. Molt was significantly protracted in all except the 60% premolt group as a result of both increased shedding interval and decreased feather growth rates. Their new plumage weighed less than that of control birds, and their remiges were slightly shorter and often deformed or achromatic. The occurrence of fault bars corresponded to the times when the birds were handled, but was not correlated with other plumage defects. Surviving birds of the 60% premolt group did not molt until allowed to feed ad libitum, but then produced a normal plumage in about two-thirds of the time required by the controls. To summarize, molt is a very conservative aspect of self maintenance that is distorted only by planes of malnutrition that free-living sparrows either do not encounter during the summer or do not survive.
Social interactions and dominance relationships between female and male Columbian ground squirrels
Authors: Murie Jan O. , Harris Margaret A.
Published: August 2008

The nature of social interactions between adult male and adult female Columbian ground squirrels (Spermophilus columbianus) was studied over 5 years in southwestern Alberta to assess relative dominance and factors affecting dominance relationships between the sexes. Most amicable interactions occurred before females bred; thereafter, most interactions were agonistic. Males chased females more often than they were chased by them before females bred, but thereafter the opposite was true, until about the time juveniles first emerged from natal burrows. This relative dominance by females after breeding was more pronounced in interactions with subordinate males versus dominant, territorial males, with neighboring males versus resident males, and within a female's core area of activity and close to her nest burrow versus outside the core area and more distant from her nest burrow. Females that were lactating showed greater dominance than those not lactating, especially late in the lactation period. The general pattern of female dominance towards males is common in other species of ground-dwelling sciurids but appears to be not strongly related to level of sociality.
External ultrastructure of sensilla on the antennal flagellum of a female black fly, Simulium arcticum (Diptera: Simuliidae)
Authors: Shipp J. L. , Sutcliffe J. F. , Kokko E. G.
Published: August 2008

The distribution, relative abundance, and external ultrastructure of the antennal flagellar spines, hairs, and pegs of female Simulium arcticum (IIL-3) and (IIS-10.11) are described. Five types of sensilla were found; two are probably contact chemosensilla, with one type at the flagellar tip and the other type on the general flagellar surface, and the three others are probably olfactory sensillae, also on the flagellar surface. Results from this study are compared with those of previous studies of black fly antennal sensilla.