bluuebunny/crossref_metadata_2025 huggingface dataset:
Accumulation of heavy metals in food web components across a gradient of lakes
Authors: Chen Celia Y. , Stemberger Richard S. , Klaue Bjorn , Blum Joel D. , Pickhardt Paul C. , Folt Carol L.
Published: June 2010

Recent studies have emphasized the need for understanding the accumulation and fate of metal contaminants at different trophic levels and across a broad spectrum of lake types. To address both issues, metal concentrations (Hg, Zn, Cd, As, and Pb) were measured in the water, two size fractions of zooplankton, and fish from 20 lakes in contaminated to pristine watersheds in the northeastern United States. Our goals were to examine links between watershed characteristics and aqueous metal levels in lakes and relationships between aqueous concentrations, metal burdens in different plankton groups and in fish. Two pairs of metals, (1) Hg and Zn and (2) As and Pb, exhibited strong similarities both in the factors that predict their concentrations in water and in the patterns of accumulation in particular trophic levels. Aqueous concentrations of Hg and Zn were highest in cool water lakes, whereas As and Pb were highest in more eutrophic lakes in agricultural areas. Aqueous Cd concentrations were closely correlated with the land‐use variables, percentage of agricultural land, and road densities. Similarly, Hg and Zn both biomagnified from small plankton (45–202 µm) to macrozooplankton (>202 mm) and from macrozooplankton to fish. In contrast, bioaccumulation of both As and Pb diminished with increasing trophic level. Although aqueous metal and zooplankton metal levels were not significant predictors of As and Pb levels in fish, metal levels in zooplankton were predictive of Hg and Zn in fish, suggesting that sources of bioaccumulation differ for different metals. Our findings demonstrate the importance of investigating upper and lower trophic levels separately, to fully understand metal transfer pathways in aquatic food webs.
Estimating the groundwater contribution into Florida Bay via natural tracers, 222Rn and CH4
Authors: Corbett D. Reide , Dillon Kevin , Burnett William , Chanton Jeffrey
Published: June 2010

Groundwater may represent a significant pathway for nutrients and other dissolved solutes into Florida Bay, especially near the Keys where wastewater disposal practices add large amounts of nitrogen and phosphorus to the subsurface each year. Previously, we suggested that high water column inventories of the tracers 222Rn and CH4 may be indicative of groundwater discharge. In this study, we employed mass balance calculations to determine that the total benthic fluxes required to maintain the measured water column tracer inventories were significantly larger than diffusive fluxes and varied between 4.2–5.6 dpm m−2 min−1 and 5.8–15.4 nmoles m−2 min−1 for 222Rn and CH4, respectively. Independent estimates of the diffusive flux and porewater activities/concentrations allowed us to calculate an advective groundwater velocity, assuming that the difference between the total benthic flux (given above) and the diffusive flux is driven by seepage‐driven porewater advection. These calculated velocities ranged from 0.2 to 4.3 cm d−1 for all sites, tracers, and sampling periods, with a best estimate of approximately 1.7 cm d−1. These estimates of groundwater velocities compare very well with previous measurements of groundwater flux (1–3 cm d−1) at the same sites via seepage meters.
Empirical analysis of the effect of phosphorus limitation on algal food quality for freshwater zooplankton
Authors: Brett Michael T. , Müller‐Navarra Dörthe C. , Sang‐Kyu Park
Published: June 2010

Herbivorous zooplankton production is often constrained by algal food quality, and variation in algal food quality has been attributed to its phosphorus (P) content. To test the hypothesis that mineral P limitation is an important constraint on freshwater herbivorous zooplankton production, we conducted a quantitative analysis of published data on lake seston carbon to phosphorus (C:P) ratios and daphnid growth responses to P‐limited algal diets. Our summary of 276 observations of mean lake seston C:P ratios showed 38% exceeded a critical threshold of 300, above which daphnid production is often predicted to be limited by algal P content. Our analysis of 91 observations of daphnid growth responses to nutrient‐limited algal diets indicates the true daphnid critical threshold lies within the range of 225–375. Algal food quality is consistently reduced at algal C:P ratios above 300; however, the predicted reduction in algal food quality with P limitation is greater than the observed reduction at critical thresholds <390. Mineral P limitation of Daphnia production may be quite strong in some lakes; however, the production of most zooplankton taxa would not be expected to be limited by mineral P in a large proportion of lakes. After correcting for the algal C:P ratio, large differences in food quality were found between the major algal taxa, with diatoms and cryptophytes high food quality, chlorophytes intermediate food quality, and small ingestible cyanophytes very low food quality. A Monte Carlo simulation indicated that shifts in algal community composition similar to those seen during seasonal succession or across lake trophic state gradients explained four times more variability in daphnid growth rates across a range of seston C:P ratios representative of natural lakes. Overall these results tend to support the mineral P limitation hypothesis for daphnids, but they also suggest other factors will be the primary determinants of algal food quality for most zooplankters in most lakes.
Motion of dinoflagellates in a simple shear flow
Authors: Karp‐Boss Lee , Boss Emmanuel , Jumars Peter A.
Published: June 2010

Turbulence can be highly significant to dinoflagellates by affecting their swimming motion. We examined the effects of simple shear flow on swimming trajectories and orientations of two species of dinoflagellates Glenodinium foliaceum and Alexandrium catenella. In the absence of either shear or a cue that can cause directional motion, swimming orientations of both species were insignificantly different from random. Although cells of G. foliaceum maintained their random swimming orientations upon exposure to shear, swimming orientations of both single cells and chains of A. catenella were affected by shear. Magnitude of the effect increased with shear rate. Changes in decorrelation times, as a result of exposure to shear, were observed for both species, providing another indication that shear affects swimming behavior. Decorrelation times for the swimming directions of both species were of the same order as the characteristic time scale of turbulence that would produce shear rates comparable to those examined in this study. Theoretical models that assess the effects of turbulence on vertical migration of dinoflagellates and predator‐prey interactions commonly assume that swimming motion of dinoflagellates in the presence of shear flow can be described by simple superposition of the flow on the swimming motion in the absence of flow. Our results suggest that this assumption is not universally true.
Modeling basin‐scale internal waves in a stratified lake
Authors: Hodges Ben R. , Imberger Jörg , Saggio Angelo , Winters K. B.
Published: June 2010

Basin—scale internal waves provide the driving forces for vertical and horizontal fluxes in a stratified lake below the wind‐mixed layer. Thus, correct modeling of lake mixing and transport requires accurate modeling of basin‐scale internal waves: examining this capability with a hydrostatic, z‐coordinate three‐dimensional (3D) numerical model at coarse grid resolutions is the focus of this paper. It is demonstrated that capturing the correct thermocline forcing with a 3D mixed‐layer model for surface dynamics results in a good representation of low‐frequency internal wave dynamics. The 3D estuary and lake computer model ELCOM is applied to modeling Lake Kinneret, Israel, and is compared with field data under summer stratification conditions to identify and illustrate the spatial structure of the lowest‐mode basin‐scale Kelvin and Poincaré waves that provide the largest two peaks in the internal wave energy spectra. The model solves the unsteady Reynolds‐averaged Navier‐Stokes equations using a semi‐implicit method similar to the momentum solution in the TRIM code with the addition of quadratic Euler‐Lagrange dis‐cretization, scalar (e.g., temperature) transport using a conservative flux‐limited approach, and elimination of vertical diffusion terms in the governing equations. A detailed description is provided of turbulence closure for the vertical Reynolds stress terms and vertical turbulent transport using a 3D mixed‐layer model parameterized on wind and shear energy fluxes instead of the convential eddy viscosity/diffusivity assumption. This approach gives a good representation of the depth of the mixed‐layer at coarse vertical grid resolutions that allows the internal waves to be energized correctly at the basin scale.
Interannual variation in the thermal structure of clear and colored lakes
Authors: Snucins Ed , John Gunn
Published: June 2010

We used end‐of‐summer temperature profiles to examine the thermal structure of 86 small (<500 ha) lakes in Killarney Park, Ontario, Canada, during one cool (1997) and two extremely warm years (1998 and 1999). The main effect of the warm years, which had unusually high air temperatures during the spring, relative to the cool year was to create warmer surface waters, shallower mixing depths, and stronger metalimnetic thermal gradients in nearly all lakes. Changes in deep water temperatures differed between clear (DOC < 2 mgL 21 ) and colored (DOC < 4 mg L−1) lakes. During warm years, the volume of cold water (<10°C) was reduced in clear lakes. In colored lakes, deep water temperatures were more stable, and cold water volume actually increased during one warm year. We suggest that clear lakes will be more sensitive than colored lakes to the warming effects of climate change. Because clear lakes exhibit large thermal changes in response to small differences in DOC, they will also be more sensitive to changes in DOC levels associated with altered hydrological inputs, climate change, or acidification.
Chemically regulated feeding by a midwater medusa
Authors: Tamburri Mario N. , Halt Magdalena N. , Robison Bruce H.
Published: June 2010

Planktonic cnidarians are principal predators in the vast habitats between the ocean's surface and the deep‐sea floor. Almost nothing is known, however, about the chemical ecology of these fragile midwater animals because of difficulties associated with collecting healthy specimens and con‐ducting experiments in the field. With the use of a remotely operated vehicle, we found that the hydromedusa Mitrocoma cellularia is not a passive “drift‐net” predator. This relatively simple gelatinous organism reacted to both the taste and smell of prey in the laboratory and in situ. Our results comprise the first definitive demonstration that a species of pelagic cnidarian responds behaviorally to chemical signals, and they lend new insight into the role of chemoreception in structuring mid‐water communities.
Intense winter heterotrophic production stimulated by benthic resuspension
Authors: Cotner James B. , Johengen Thomas H. , Biddanda Bopaiah A.
Published: June 2010

A major episodic sediment resuspension event (25‐yr high), which was triggered by atmospheric and water column instability in an El Niň;o year, temporarily altered the dynamics of autotrophy and heterotrophy in Lake Michigan. Resuspended sediments, rich in organic and inorganic nutrients, especially phosphorus, stimulated heterotrophic production despite low water temperatures (2ºC or less). During the resuspension event, southern basin winter heterotrophic bacterial productivity was high (64% of summertime productivity), especially along the margins of the lake. The mean bacterial cell size increased in regions where productivity was highest during the resuspension event. Although resuspended sediments stimulated bacterial secondary productivity, they simultaneously decreased water‐column light availability and autotroph biomass. Consequently, heterotrophic bacteria were temporally decoupled from the commonly recognized source of organic matter for bacterial production—photoautotrophy. Variation in the magnitude and frequency of these resuspension events likely influences variation in interannual productivity in this system. Such previously underappreciated, intermittent, and ephemeral benthic‐pelagic exchange events may significantly influence plankton dynamics and biogeochemical cycling in coastal marine and freshwater ecosystems.
Genome size distributions indicate variability and similarities among marine viral assemblages from diverse environments
Authors: Steward Grieg F. , Montiel Janine L. , Azam Farooq
Published: June 2010

Pulsed field gel electrophoresis (PFGE) was used to determine the size distributions of virus‐like DNA in seawater from diverse environments (Arctic Ocean, Ross Sea, coastal Pacific Ocean, and northern Adriatic Sea). Changes in DNA banding patterns indicated that shifts in the viral assemblage composition occurred on the order of #2 d during an intense dinoflagellate bloom in coastal Pacific waters. Different DNA banding patterns from diverse locations also indicated spatial variability in composition, but all of the samples analyzed had similar features. Size frequency distributions for virus‐like genomes (VLGs) were multimodal, with major peaks occurring around 31–36 kilobases (kb) and 58–63 kb. The smallest discrete band resolved was 26 kb, the largest was >200 kb, and the overall mean VLG size was 50 ± 4 kb (mean ± SD, n = 30). On average in surface seawater, >90% of the VLGs occurred in the 26–69 kb size range, and at least half were between 28 and 45 kb. This first extensive survey of viral genome sizes in seawater indicates that most marine viruses have physical properties similar to other known viruses. The distributions revealed that the vast majority of the detected VLGs had sizes typical of bacteriophages, whereas only a few percent were in the size range of known algal viruses.
Allocation of particulate organic carbon from different sources in two contrasting estuaries of southeastern U.S.A.
Authors: Otero Ernesto , Culp Randolph , Noakes John E. , Hodson Robert E.
Published: June 2010

Particulate organic carbon (POC) is an important component in the carbon cycle of estuarine systems. Many studies have utilized carbon isotopic composition (δ13C‐POC) to estimate the origin of POC. Most of the early studies were restricted to areas of minimum terrestrial inputs of POC, whereas later studies used multiple stable isotope analysis. In our study, we assess the proportion of POC from C3 and C4 plants and microalgae in two terrestrially affected, contrasting estuaries of the southeastern U.S.A.: the Altamaha (Piedmont) and the Satilla (blackwater) Rivers. Our analysis was based on a mass balance equation, taking into consideration the estimated amounts of microalgae and C3 and C4 plant material. Analysis of δ13C of extracted chlorophyll a (Chl a) was used to estimate the isotopic signature of microalgae to constrain the three endmember mass balance. The maximum concentration of POC fluctuated between 9 and 11 mg C L−1, coinciding with the period of maximum riverine flow. The POC represented 50–70% of the total organic carbon. However, large fluctuations were observed, suggesting important tidal‐ and wind‐driven resuspension. The δ13C‐POC ranged from −21 to −28‰, being more depleted at lower salinities. This indicates rapid dilution of terrestrially derived material with estuarine‐ or marine‐derived material. The Chl a concentration was maximal during summer in upstream stations of the Altamaha estuary, while the Satilla generally showed a midestuary maximum. The δ13C of Chl a ranged from −20.7 to −31.43‰, indicating isotopically depleted inputs of microalgal‐derived material (MaDM). Our results suggest that MaDM is the dominant component of POC in the Altamaha River during summer, whereas the C3 component is dominant during periods of lower productivity and high flushing. Although MaDM is significant in the Satilla estuary, most of the POC consists of material derived from C3 and C4 plants.
UV radiation and low calcium as mutual stressors for Daphnia
Authors: Hessen Dag O. , Rukke Nina Alstad
Published: June 2010

The cladocerans Daphnia magna and D. tenebrosa were exposed to daily 6‐h ultraviolet (UV) radiation along a gradient of ambient Ca in the medium (0.5, 1.0, 5.0, and 10 mg Ca L−1) at nearly constant conductivity. Integrated irradiance over 300–400 nm was 35.95 W m−2, corresponding to maximum outdoor intensities during midsummer. D. magna was most susceptible to UV radiation, but the UV susceptibility for both species increased significantly with decreased Ca content. Ca uptake (45Ca) was apparently not influenced by short‐term (3 h) UV exposure; thus, although lipid peroxidation and membrane damage are likely mechanisms for impaired ionic uptake, the overall role of low Ca may be reduced stress tolerance. While general conclusions on other species and taxa are premature, the data indicate that water hardness could be a major determinant to UV susceptibility among Ca‐demanding zooplankton species like Daphnia.
An isotopic labeling method for determining production of volatile organohalogens by marine microalgae
Authors: Murphy Cormac D. , Moore Robert M. , White Robert L.
Published: June 2010

An isotopic method has been developed to establish the biological production of volatile organohalogens. The marine microalgae Porphyridium purpureum and Dunaliella tertiolecta were grown in seawater medium containing NaH13CO3, and volatile organohalogens were extracted and analyzed by gas chromatography‐mass spectrometry (GC‐MS). Isotopically labeled methyl halides were formed in each microalgal culture, and the 13CHCl3 found in the P. purpureum culture confirmed the production of chloroform reported by Scarratt and Moore (Limnol. Oceanogr. 1999. 44: 703–707). No incorporation of 13C into dichloromethane was observed, even though slightly increased CH2Cl2 concentrations were detected in both algal cultures at the end of the incubation period.
Diffraction Techniques in Structural Biology
Authors: Egli Martin
Published: June 2010

A detailed understanding of chemical and biological function and the mechanisms underlying the molecular activities ultimately requires atomic‐resolution structural data. Diffraction‐based techniques such as single‐crystal X‐ray crystallography, electron microscopy, and neutron diffraction are well established and they have paved the road to the stunning successes of modern‐day structural biology. The major advances achieved in the last 20 years in all aspects of structural research, including sample preparation, crystallization, the construction of synchrotron and spallation sources, phasing approaches, and high‐speed computing and visualization, now provide specialists and nonspecialists alike with a steady flow of molecular images of unprecedented detail. The present unit combines a general overview of diffraction methods with a detailed description of the process of a single‐crystal X‐ray structure determination experiment, from chemical synthesis or expression to phasing and refinement, analysis, and quality control. For novices it may serve as a stepping‐stone to more in‐depth treatises of the individual topics. Readers relying on structural information for interpreting functional data may find it a useful consumer guide.Curr. Protoc. Nucleic Acid Chem. 41:7.13.1‐7.13.35. © 2010 by John Wiley & Sons, Inc.
Engineering Three‐Dimensional Collagen Matrices to Provide Contact Guidance during 3D Cell Migration
Authors: Provenzano Paolo P. , Eliceiri Kevin W. , Inman David R. , Keely Patricia J.
Published: June 2010

Cell invasion requires that cells navigate complex three‐dimensional matrices in vivo. Topological cues are provided and three‐dimensional cell migration and invasion facilitated by the alignment of collagen fibers proximal to tumors. In order to better understand the molecular mechanisms by which cells recognize and migrate along aligned matrices, in vitro assays are needed that recapitulate topological features of the in vivo matrix. Here, we describe two approaches for creating aligned three‐dimensional collagen matrices, both dependent and independent of cell‐mediated alignment. Approaches to quantify alignment and visualize the collagen matrix relative to the cells by second‐harmonic generation are included. These assays are readily adaptable to a variety of cells and biological questions related to three‐dimensional cell migration. Curr. Protoc. Cell Biol. 47:10.17.1‐10.17.11. © 2010 by John Wiley & Sons, Inc.
MultiPipMaker: A Comparative Alignment Server for Multiple DNA Sequences
Authors: Elnitski Laura , Burhans Richard , Riemer Cathy , Hardison Ross , Miller Webb
Published: June 2010

The MultiPipMaker World Wide Web server (http://www.bx.psu.edu) provides a tool for aligning multiple DNA sequences and visualizing regions of conservation among them. This unit describes its use and gives an explanation of the resulting output files and supporting tools. Features provided by the server include alignment of up to 20 very long genomic sequences, output choices of a true, nucleotide‐level multiple alignment and/or stacked, pairwise percent identity plots, and support for user‐specified annotations of genomic features and arbitrary regions, with clickable links to additional information. Input sequences other than the reference can be fragmented, unordered, and unoriented. Curr. Protoc. Bioinform. 30:10.4.1‐10.4.14. © 2010 by John Wiley & Sons, Inc.
Prevalence, practice patterns, and evidence for chronic neck pain
Authors: Goode Adam P. , Freburger Janet , Carey Timothy
Published: June 2010

Objective

To estimate the prevalence of chronic neck pain in North Carolina, to describe health care use (providers, treatments, and diagnostic testing) for chronic neck pain, and to correlate health care use with the current best evidence.

Methods

We used data from a cross‐sectional telephone survey of a representative sample of North Carolina households in 2006. A total of 5,357 households were contacted in 2006 to identify 141 noninstitutionalized adults ages ≥21 years with chronic neck pain and no chronic low back pain. The subjects were interviewed about their health and health care use (i.e., provider, tests, and treatments). Patterns of health care use were compared with current systematic reviews.

Results

The estimated prevalence of chronic neck pain in 2006 among noninstitutionalized individuals for the state of North Carolina was 2.2% (95% confidence interval [95% CI] 1.7–2.6). Individuals with chronic neck pain were middle‐aged (mean age 48.9 years) and the majority of subjects were women (56%) and non‐Hispanic white (81%). The subjects saw a mean of 5.21 (95% CI 4.8–5.6) provider types and had a mean of 21 visits. The types of treatments subjects reported varied, with treatments such as electrotherapy stimulation (30.3%), corsets or braces (20.9%), massage (28.1%), ultrasound (27.3%), heat (57.0%), and cold (47.4%) having unclear or little benefit based on the current best available reviews.

Conclusion

Based on the current evidence for best practice, our findings indicate overutilization of diagnostic testing, narcotics, and modalities, and underutilization of effective treatments such as therapeutic exercise.
Validity and responsiveness of the Michigan hand questionnaire in patients with rheumatoid arthritis: A multicenter, international study
Authors: Waljee Jennifer F. , Chung Kevin C. , Kim H. Myra , Burns Patricia B. , Burke Frank D. , Wilgis E. F. Shaw , Fox David A.
Published: June 2010

Objective

Millions of patients experience the disabling hand manifestations of rheumatoid arthritis (RA), yet few hand‐specific instruments are validated in this population. Our objective was to assess the reliability, validity, and responsiveness of the Michigan Hand Questionnaire (MHQ) in patients with RA.

Methods

At enrollment and at 6 months, 128 RA patients with severe subluxation of the metacarpophalangeal joints completed the MHQ, a 37‐item questionnaire with 6 domains: function, activities of daily living (ADL), pain, work, aesthetics, and satisfaction. Reliability was measured using Spearman's correlation coefficients between time periods. Internal consistency was measured using Cronbach's alpha. Construct validity was measured by correlating MHQ responses with the Arthritis Impact Measurement Scales 2 (AIMS2). Responsiveness was measured by calculating standardized response means (SRMs) between time periods.

Results

The MHQ demonstrated good test–retest reliability (r = 0.66, P < 0.001). Cronbach's alpha scores were high for ADL (α = 0.90), function (α = 0.87), aesthetics (α = 0.79), and satisfaction (α = 0.89), indicating redundancy. The MHQ correlated well with AIMS2 responses. Function (r = −0.63), ADL (r = −0.77), work (r = −0.64), pain (r = 0.59), and summary score (r = −0.74) were correlated with the physical domain. Affect was correlated with ADL (r = −0.47), work (r = −0.47), pain (r = 0.48), and summary score (r = −0.53). Responsiveness was excellent among arthroplasty patients in function (SRM 1.42), ADL (SRM 0.89), aesthetics (SRM 1.23), satisfaction (SRM 1.76), and summary score (SRM 1.61).

Conclusion

The MHQ is easily administered, reliable, and valid to measure rheumatoid hand function, and can be used to measure outcomes in rheumatic hand disease.
Amorphous Calcium Carbonate is Stabilized in Confinement
Authors: Stephens Christopher J. , Ladden Sophie F. , Meldrum Fiona C. , Christenson Hugo K.
Published: June 2010

Biominerals typically form within localized volumes, affording organisms great control over the mineralization process. The influence of such confinement on crystallization is studied here by precipitating CaCO3 within the confines of an annular wedge, formed around the contact point of two crossed half‐cylinders. The cylinders are functionalized with self‐assembled monolayers of mercaptohexadecanoic acid on gold. This configuration enables a systematic study of the effects of confinement since the surface separation increases continuously from zero at the contact point to macroscopic (mm) separations. While oriented rhombohedral calcite crystals form at large (>10 µm) separations, particles with irregular morphologies and partial crystallinity are observed as the surface separation approaches the dimensions of the unconfined crystals (5–10 µm). Further increase in the confinement has a significant effect on the crystallization process with flattened amorphous CaCO3 (ACC) particles being formed at micrometer separations. These ACC particles show remarkable stability when maintained within the wedge but rapidly crystallize on separation of the cylinders. A comparison of bulk and surface free‐energy terms shows that ACC cannot be thermodynamically stable at these large separations, and the stability is attributed to kinetic factors. This study therefore shows that the environment in which minerals form can have a significant effect on their stability and demonstrates that ACC can be stabilized with respect to the crystalline polymorphs of CaCO3 by confinement alone. That ACC was stabilized at such large (micrometer) separations is striking, and demonstrates the versatility of this strategy, and its potential value in biological systems.
Pulmonary and systemic toxicity following exposure to nickel nanoparticles
Authors: Phillips James I. , Green Francis Y. , Davies John C.A. , Murray Jill
Published: June 2010

Nanoparticles are being used in ever increasing numbers in a range of industrial and medical products. Questions surrounding their potential to cause toxic effects in humans have been raised. Although animal experiments predict that nanoparticles are more toxic than their larger counterparts there are few descriptions in the literature of human exposure. A case described in 1994 has been re‐examined from a pathology perspective. The subject, a 38‐year‐old previously healthy male, inhaled nanoparticles of nickel while spraying nickel onto bushes for turbine bearings using a metal arc process. He died 13 days after being exposed and the cause of death at autopsy was adult respiratory distress syndrome (ARDS). Nickel particles <25 nm in diameter were identified in lung macrophages using transmission electron microscopy. High levels of nickel were measured in his urine and his kidneys showed evidence of acute tubular necrosis. Am. J. Ind. Med. 53:763–767, 2010. © 2010 Wiley‐Liss, Inc.
Feeding ecology of Bornean orangutans (Pongo pygmaeus morio) in Danum Valley, Sabah, Malaysia: a 3‐year record including two mast fruitings
Authors: Kanamori Tomoko , Kuze Noko , Bernard Henry , Malim Titol P. , Kohshima Shiro
Published: June 2010

We observed the diet and activity of Bornean orangutans (Pongo pygmaeus morio) in the primary lowland dipterocarp forests of Danum Valley, Sabah, Malaysia, during 2005–2007, including two mast fruitings. We collected 1,785 hr of focal data on 26 orangutans. We identified 1,466 samples of their food plants and conducted a fallen fruit census to monitor fruit availability in the study area. Their activity budget was 47.2% feeding, 34.4% resting, and 16.9% traveling. Fruits accounted for the largest part (60.9%) of feeding time, especially during mast fruiting periods (64.0–100%), although the percentages of leaves (22.2%) and bark (12.3%) were higher than those reported for P. abelii and P. pygmaeus wurmbii. Although 119 genera and 160 plant species were consumed by focal animals, only 9 genera accounted for more than 3% of feeding time (total: 67.8% for 9 genera). In particular, the focal orangutans fed intensively on Ficus and Spatholobus during most of the study period, especially in periods of fruit shortage. The percentage of fruit feeding changed markedly from 11.7 to 100% across different months of the year, and was positively correlated with the amount of fallen fruit. When fruit feeding and availability decreased, orangutans fed primarily on leaves of Spatholobus and Ficus, and the bark of Spatholobus and dipterocarp. The percentage of time devoted to feeding during mast fruitings, when the orangutans foraged almost exclusively on fruits, was lower than during seasons when the orangutan diet included leaves and bark as well as fruits. Resting increased as feeding decreased in the late stage of each fruiting season, suggesting that the orangutans adopted an energy‐minimizing strategy to survive the periods of fruit shortage by using energy stored during the fruit season. Am. J. Primatol. 72:820–840, 2010. © 2010 Wiley‐Liss, Inc.
Marriage patterns in a Mesoamerican peasant community are biologically adaptive
Authors: Little Bertis B. , Malina Robert M.
Published: June 2010

Differential investment in offspring by parental and progeny gender has been discussed and periodically analyzed for the past 80 years as an evolutionary adaptive strategy. Parental investment theory suggests that parents in poor condition have offspring in poor condition. Conversely, parents in good condition give rise to offspring in good condition. As formalized in the Trivers‐Willard hypothesis (TWH), investment in daughters will be greater under poor conditions while sons receive greater parental investment under good conditions. Condition is ultimately equated to offspring reproductive fitness, with parents apparently using a strategy to maximize their genetic contribution to future generations. Analyses of sex ratio have been used to support parental investment theory and in many instances, though not all, results provide support for TWH. In the present investigation, economic strategies were analyzed in the context of offspring sex ratio and survival to reproductive age in a Zapotec‐speaking community in the Valley of Oaxaca, southern Mexico. Growth status of children, adult stature, and agricultural resources were analyzed as proxies for parental and progeny condition in present and prior generations. Traditional marriage practice in Mesoamerican peasant communities is patrilocal postnuptial residence with investments largely favoring sons. The alternative, practiced by ∼25% of parents, is matrilocal postnuptial residence which is an investment favoring daughters. Results indicated that sex ratio of offspring survival to reproductive age was related to economic strategy and differed significantly between the patrilocal and matrilocal strategies. Variance in sex ratio was affected by condition of parents and significant differences in survival to reproductive age were strongly associated with economic strategy. While the results strongly support TWH, further studies in traditional anthropological populations are needed. Am J Phys Anthropol 143:501–511, 2010. © 2010 Wiley‐Liss, Inc.
Versuche zur Tragfähigkeit von Ankerplatten mit einbetonierten Kopfbolzendübeln in schmalen Stahlbetonstützen
Authors: Fromknecht Stephan , Odenbreit Christoph , Dorka Uwe
Published: June 2010

Müssen große Lasten von Stahl‐ in Betonbauteile eingebracht werden, sind Ankerplattendetails mit aufgeschweißten Kopfbolzendübeln oft praktikable Lösungen. Dies gilt auch für die Befestigung von Stahlträgern an Stützen aus Stahlbeton. Hier können die Ankerplatten z. B. bauseits an der Schalung befestigt und mit dem Ortbeton einbetoniert werden.

Die Dimensionierung dieser Einbauteile kann, wie auch die Berechnung von nachträglich installierten Befestigungsmitteln, derzeit nach Europäischen Technischen Zulassungen (ETA) erfolgen. Im Unterschied zu nachträglich installierten Befestigungen ist für die Ankerplatte mit einbetonierten Kopfbolzendübeln eine rechnerische Nutzung der Tragfähigkeit der Bewehrung möglich. Allerdings führen die diesbezüglichen Regelungen – im Vergleich zu den in den Versuchen ermittelten Tragfähigkeiten – rechnerisch zu stark eingeschränkten Tragfähigkeiten. Dies beruht einerseits auf der Reduktion der Tragfähigkeit wegen geringer Randabstände und andererseits auf der stark eingeschränkten Nutzbarkeit der Bewehrung.

Im folgenden Beitrag werden Versuchsergebnisse vorgestellt, welche den Einfluss der Betondruckfestigkeit, der Verankerungslänge, der Lastexzentrizität sowie der Bewehrungsmenge und ‐position auf das Versagensgeschehen und die Tragfähigkeit zeigen.

Results of Experimental Investigations on the Load‐Bearing Capacity of Steel Anchor Plates with in Concrete Encased Headed Studs in Reinforced Narrow Concrete Columns

Anchor plates with welded shear studs are often used to transfer high loads from steel to reinforced concrete elements. This is for example the case for the fixation of steel beams to reinforced concrete columns. The anchor plates are fixed on site on the formwork and cast in‐place in the concrete.

The design is calculated according to European Technical Approvals like the design of post‐installed anchors. In contrast to post‐installed fastenings, the utilisation of the reinforcement of in concrete encased headed studs is theoretically possible. But the regulations of the ETAs lead to great reductions in the analysed load‐bearing capacities compared to the capacities, obtained in tests. These tests have been conducted to investigate the load bearing behaviour and failure modes of anchor plates, especially in narrow reinforced concrete columns.

In the following article the results of the experimental investigations are presented, which show the influence of concrete compression strength, shear stud length, load eccentricity as well as amount and position of reinforcement.
Experimentelle und numerische Untersuchungen zum Tragverhalten von Stahlbetondecken mit kugelförmigen Hohlkörpern
Authors: Abramski Marcin , Albert Andrej , Pfeffer Karsten , Schnell Jürgen
Published: June 2010

Massive Flachdecken erweisen sich in Hoch‐ und Industriebau häufig als insgesamt überlegenes Deckensystem. Die hohe Eigenlast dieser Decken kann ihren Anwendungsbereich jedoch einschränken. Eine sinnvolle Abhilfe schafft dann die Integration von Hohlkörpern in der neutralen Zone, weil hierdurch eine spürbare Gewichtsreduktion eintritt. Neben der Eigenlast wird auch der Verbrauch der unter ökologischen Gesichtspunkten wesentlichen Ressourcen Betonstahl und Zement deutlich verringert. Die Hohlräume beeinflussen vor allem die Querkrafttragfähigkeit solcher Decken. Vier Versuchsserien, die mit kugelförmigen Hohlkörperdecken des Systems “cobiax” durchgeführt wurden, werden in diesem Beitrag beschrieben. Aus den Versuchen wird ein Abminderungsfaktor zur Beschreibung des Querkrafttragverhaltens abgeleitet, der auch in die kürzlich erteilte allgemeine bauaufsichtliche Zulassung des Deckensystems eingegangen ist. Die Nachrechnung der Versuche mit der Finite‐Elemente‐Methode zeigt eine gute Übereinstimmung von Numerik und Experiment, so dass in der Weiterentwicklung Parameterstudien auf dieser Grundlage zur Ergänzung von Versuchen hilfreich sein werden.

Experimental and Numerical Investigation of the Bearing Behaviour of Hollow Core Slabs

Massive flat slabs have proven to be the most appropriate ceiling system for structural and industrial engineering. However the high dead load of these slabs might reduce their field of application. This problem can be solved by void formers that are placed in the neutral zone. These block‐outs cause a noticeable reduction of weight. Furthermore, the masses of ecologically important resources like reinforcement steel and cement can be reduced as well.

The shear bearing capacity is significantly influenced by these block‐outs. This article describes four test series with spherical void former floors of the system “cobiax”. A reduction factor for the shear bearing capacity is derived from these tests. That factor was also introduced in the technical approval for this slab system which has been issued recently. A comparison to a calculation with the finite element method shows that the numerical results and the results of the tests are quite similar. In future research, parameter studies based on the finite element method might be helpful additional to further tests.
Metabolic pathways and fermentative production of L‐aspartate family amino acids
Authors: Park Jin Hwan , Lee Sang Yup
Published: June 2010

The L‐aspartate family amino acids (AFAAs), L‐threonine, L‐lysine, L‐methionine and L‐isoleucine have recently been of much interest due to their wide spectrum of applications including food additives, components of cosmetics and therapeutic agents, and animal feed additives. Among them, L‐threonine, L‐lysine and L‐methionine are three major amino acids produced currently throughout the world. Recent advances in systems metabolic engineering, which combine various high‐throughput omics technologies and computational analysis, are now facilitating development of microbial strains efficiently producing AFAAs. Thus, a thorough understanding of the metabolic and regulatory mechanisms of the biosynthesis of these amino acids is urgently needed for designing system‐wide metabolic engineering strategies. Here we review the details of AFAA biosynthetic pathways, regulations involved, and export and transport systems, and provide general strategies for successful metabolic engineering along with relevant examples. Finally, perspectives of systems metabolic engineering for developing AFAA overproducers are suggested with selected exemplary studies.
Molecular modeling and NMR studies of benzyl substituted mannosyl trisaccharide binding to two mannose‐specific lectins: Allium sativam agglutinin I and Concanavalin A
Authors: Mazumder Parichita , Mukhopadhyay Chaitali
Published: June 2010

The interaction of trimannoside, α−benzyl 3, 6‐di‐O‐(α‐D‐mannopyranosyl)‐α‐D‐mannopyranoside, 1 with ASAI (Allium sativam agglutinin I, garlic lectin) was studied to reveal the conformational preferences of this ligand in bound‐state and detailed binding mode at atomic level. The binding phenomenon was then compared with another well‐known mannose‐binding lectin, ConA (Concanavalin A). Structural studies of the ligand in free state were done using NMR spectroscopy and Molecular Dynamics simulations. It is found that the substituted‐trimannoside can undergo conformational transitions in solution, with one major and one minor conformation per glycosidic linkage (α 1→3 and α 1→6). On the other hand in the bound‐state only one of the two major conformations was significantly populated. The role of phenyl ring in the binding process was explored. An extended binding site was observed for the trimannoside in ASAI utilizing the aromatic substituent, which is not seen in ConA. Binding data from difference absorption spectroscopy supported this fact that the binding of benzyl‐substituted ligand is tighter with ASAI than ConA. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 952–967, 2010.
Conformations of stevastelin C3 analogs: Computational deconvolution of NMR data reveals conformational heterogeneity and novel motifs
Authors: Jogalekar Ashutosh S.
Published: June 2010

The stevastelins are depsipeptide natural products that show valuable immunomodulatory and phosphatase inhibitory activity. A previous report described the synthesis, conformational analysis, and biological activity of modified diastereomeric C3 analogs (1) of these molecules and deduced a single dominant conformational scaffold for each of the six benzylated stevastelin diastereomers in solution. In this study, we report a combined computational and experimental approach (NAMFIS) of these analogs based on geometric variables from the NMR data and extensive conformational searching that suggests a more subtle and complex distribution of conformations in solution. Although the results indicate some conformations to be similar to those previously proposed, they include novel motifs not observed earlier such as gamma turns. In addition, the NAMFIS analysis confirms dramatic changes in conformations accompanying a chirality change at the C3 center and also establishes the conformational homogeneity of the D‐serine diastereomers. The NAMFIS analysis thus suggests the use of D‐serine as a possible constraining element in peptide design and derives a set of experimental solution conformers that could shed light on the bioactive conformation of the stevastelins. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 968–976, 2010.
High‐solids biphasic CO2–H2O pretreatment of lignocellulosic biomass
Authors: Luterbacher Jeremy S. , Tester Jefferson W. , Walker Larry P.
Published: June 2010

A high pressure (200 bar) CO2–H2O process was developed for pretreating lignocellulosic biomass at high‐solid contents, while minimizing chemical inputs. Hardwood was pretreated at 20 and 40 (wt.%) solids. Switchgrass, corn stover, big bluestem, and mixed perennial grasses (a co‐culture of big bluestem and switchgrass) were pretreated at 40 (wt.%) solids. Operating temperatures ranged from 150 to 250°C, and residence times from 20 s to 60 min. At these conditions a biphasic mixture of an H2O‐rich liquid (hydrothermal) phase and a CO2‐rich supercritical phase coexist. Following pretreatment, samples were then enzymatically hydrolyzed. Total yields, defined as the fraction of the theoretical maximum, were determined for glucose, hemicellulose sugars, and two degradation products: furfural and 5‐hydroxymethylfurfural. Response surfaces of yield as a function of temperature and residence time were compared for different moisture contents and biomass species. Pretreatment at 170°C for 60 min gave glucose yields of 77%, 73%, and 68% for 20 and 40 (wt.%) solids mixed hardwood and mixed perennial grasses, respectively. Pretreatment at 160°C for 60 min gave glucan to glucose yields of 81% for switchgrass and 85% for corn stover. Biotechnol. Bioeng. 2010;107: 451–460. © 2010 Wiley Periodicals, Inc.
Measurement of S‐methylcysteine and S‐methyl‐mercapturic acid in human urine by alkyl‐chloroformate extractive derivatization and isotope‐dilution gas chromatography–mass spectrometry
Authors: Rubino Federico M , Pitton Marco , Di Fabio Daniela , Meroni Giuseppe , Santaniello Enzo , Caneva Enrico , Pappini Marco , Colombi Antonio
Published: June 2010

S‐methylcysteine (SMC) is a minor amino acid naturally excreted in human urine, a protective agent against oxidative stress and a biotransformation product of the fumigant biocide methyl bromide and of nicotine. A metabolic source of SMC is catabolism of the repair catalytic protein MGMT (EC 2.1.1.37), which specifically removes the methyl group from the modified DNA nucleotide O‐6‐methyl‐guanine to revert the normal GC base pairing. To assess the value of SMC and of S‐methylmercapturic acid (SMMA) as candidate biomarkers of proliferative phenomena, a sensitive analytical method by GC‐MS was applied in a pilot study of healthy subjects to assess their urinary elimination and the intra‐ and inter‐individual variability. Extractive alkylation with butylchloroformate‐n‐butanol‐pyridine (Husek technique) was employed for sample derivatization and isotope dilution GC‐MS with S‐[CD3]‐SMC and ‐SMMA was applied for specific and sensitive detection. To resolve the target analytes from the main coeluting interferents in the derivatized urine extract a medium‐polarity stationary phase was employed. SMMA was not detected in the morning urine of three healthy fertile‐age women followed for one month above the minimum detectable level of approx. 500 µg/L while SMC concentrations were in the 0.02–0.7 µg/mL range (n = 61) with large inter‐day and inter‐individual variations. In a young healthy male urine samples taken throughout a few days yielded concentrations in the same 90–810 µg/L range (n = 11). These preliminary results points at SMC as a candidate biomarker for the study of methylation turnover in several biochemical processes. Copyright © 2010 John Wiley & Sons, Ltd.
Simultaneous determination of norisoboldine and its major metabolite in rat plasma by ultra‐performance liquid chromatography–mass spectrometry and its application in a pharmacokinetic study
Authors: Chen Jian‐Zhong , Xu Ying , Chou Gui‐Xin , Wang Chang‐Hong , Yang Li , Wang Zheng‐Tao
Published: June 2010

Norisoboldine (NIB) is one of the main bioactive isoquinoline alkaloids in Linderae Radix. A rapid, selective and sensitive method using UPLC‐ESI/MS was first developed for simultaneous determination of NIB and norisoboldine‐9‐O‐α‐glucuronide (NIB‐Glu), its major metabolite in rat plasma. A one‐step protein precipitation with methanol was employed as sample preparation technique. Chromatographic separation was carried out on an Acquity UPLC BEH C18 column (50 × 2.1 mm, i.d. 1.7 µm) with a gradient mobile phase consisting of acetonitrile and water containing 0.1% formic acid. Detection and quantification were performed using a quadrupole mass spectrometer by selective ion reaction‐monitoring mode. Good linearity was achieved using weighted (1/x2) least squares linear regression over the concentration ranges 0.01–2 µg/mL for NIB and 0.025–25 µg/mL for NIB‐Glu. The lower limit of quantification of NIB and NIB‐Glu was 0.01 and 0.025 µg/mL, respectively. The intra‐ and inter‐day precisions (relative standard deviations) of the assay at all three quality control levels were 4.6–14.1% for NIB, and 5.0–12.2% for NIB‐Glu. The accuracies (relative error) were −13.5–8.1% for NIB and −12.8–7.6% for NIB‐Glu, respectively. This developed method was successfully applied to an in vivo pharmacokinetic study in rats after a single intravenous dose of 10 mg/kg NIB. Copyright © 2010 John Wiley & Sons, Ltd.