bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of Abiotic and Biotic Factors Influences Larval Fish Survival in an Oklahoma Stream
Authors: Harvey Bret C.
Published: May 2008

Both abiotic and biotic factors affected larval fish in Baron Fork, Oklahoma. Nighttime drift rates were very high (up to 31 larvae/m3) during normal flow. Censuses indicated that daytime abundances of larvae occupying pools were influenced significantly by the presence of juvenile and adult smallmouth bass (Micropterus dolomieui). Minnow larvae were less abundant in pools occupied by juvenile smallmouth bass and more abundant in pools with adult smallmouth bass. Experimental manipulation of adult bass supported the hypothesis that their presence benefits the larvae of other species, but pool type influenced this response. Differences between the effects of adult bass on the accumulation of larvae in main channel pools compared with side pools appeared to reflect the influence of drift. The benefit that adult bass provided the larvae of other species probably involved their impacts on juvenile bass and other small fishes, which may be the most significant predators of larval fish. The pattern of co-occurrence between adult bass and the larvae of other species in Baron Fork parallels results from lakes and smaller streams.
Trace Element Distributions in Aquatic Insects: Variations among Genera, Elements, and Lakes
Authors: Hare Landis , Tessier André , Campbell Peter G. C.
Published: May 2008

The distribution patterns of trace element contaminants (As, Cd, Cu, Pb, Zn) among the tissues of freshwater insects (Chironomus, Clinotanypus, Procladius, Hexagenia, Sialis) are both taxon and element specific. In quantity terms (micrograms per animal), the gut is the major organ of Cd accumulation, while most of the As, Cu, Pb, and Zn accumulates in the body (i.e. animal minus gut and other organs). In concentration terms (micrograms per gram), Cd, Cu, and Zn are often highest in the gut, while Pb and As are not. Much of the As, and in some genera the Pb, appears to be bound externally. Respiratory and excretory structures generally contain small proportions of the total trace element burdens, except for Cu. Trace elements are not uniformly distributed along the gut but tend to accumulate either in the mesenteron (midgut) or in the proctodeum (hindgut), depending on the element and insect concerned. The distribution patterns of most of the trace elements vary little among populations of the mayfly Hexagenia from different lakes with the exception of Cd, for which the proportion of the total Cd burden localized in the gut increases markedly with increasing Cd concentrations in the whole nymph.
Limits to Growth of Young-of-the-Year Walleye (Stizostedion vitreum vitreum): An Individual-Based Model Perspective
Authors: Madenjian Charles P.
Published: May 2008

An individual-based model (IBM) accurately described the variation in growth exhibited between young-of-the-year (YOY) walleye (Stizostedion vitreum vitreum) cohorts from Oneida Lake (New York) and western Lake Erie. The IBM was used to develop a general explanation for the wide variability in growth exhibited by YOY walleye. Length of growing season and encounter rate, λ, between YOY walleye and the prey fish set the potential for growth in a particular aquatic system. Walleye spawning observations and observed YOY prey densities in Oneida Lake versus those for western Lake Erie corroborated these modeling results. Given a specific encounter rate and length of growing season, first-year growth of walleye was further controlled by size of prey fish relative to YOY walleye size, availability of prey fish throughout the summer and early fall months, and water temperature.
Physical Behaviour of Lake Ontario with Reference to Contaminant Pathways and Climate Change
Authors: Boyce F. M. , Schertzer W. M. , Hamblin P. F. , Murthy C. R.
Published: May 2008

Current understanding of the physical behaviour of Lake Ontario is assessed. In particular, the role of water movements in the distribution and fate of contaminants is described, and our ability to anticipate the results of global climate warming on the Great Lakes is surveyed. In the past two decades, the general features of large-lake circulation and mixing have been successfully delineated, although detailed climatological studies will be required for particular sites of interest or concern. More sophisticated models of thermal structure will be needed to assess the potential consequences of climate warming, particularly in the matter of convective overturning. The process of "sediment focusing," so strongly linked to the fate of many organic contaminants, is only recently amenable to study with instruments that respect the time and space scales of resuspension and settling. The rates of transfer of gases and contaminants across the air–water interface are known to depend on wind and wave conditions; this dependence is being explored. Experience over the past 20 yr has consistently shown that large-lake studies of chemical and biological processes are difficult if not impossible to interpret in the absence of an adequate base of concurrent physical measurements.
Submerged Macrophytes in Lake Ontario: Current Knowledge, Importance, Threats to Stability, and Needed Studies
Authors: Crowder A. , Painter D. S.
Published: May 2008

The submerged limnetic community in Lake Ontario includes algae, bryophytes, and about 30 species of angiosperms. Their distribution is accurately known in some areas but not lake-wide, and a whole-lake survey is recommended. In nutrient cycling, submergents act as sinks during the summer; metals and metalloids occur in high concentrations in tissues from some areas. Known herbivores include invertebrates, fish, and waterfowl. Stands are necessary for many fish taxa as breeding or nursery habitats, and for waterfowl, but may be damaged by carp (Cyprinus carpio). Stability has been affected by water levels, sedimentation, wave and ice movement, invasive species, herbivory, eutrophication and turbidity, and contaminants. Recovery after control of P loading has occurred in Irondequoit Bay but is delayed by turbidity in the Bay of Quinte.
Rehabilitation of Lake Ontario: the Role of Nutrient Reduction and Food Web Dynamics
Authors: Hartig John H. , Kitchell James F. , Scavia Donald , Brandt Stephen B.
Published: May 2008

The Laurentian Great Lakes have a complex history of changes due to eutrophication, invasion of exotic species, and fisheries and phosphorus management practices. Remedial actions have reduced nutrient loadings and enhanced the role of food web interactions in improving water quality. Workshops sponsored through the United States – Canada international Joint Commission have addressed the relative importance of nutrient abatement and/or food web manipulation in affecting water quality trends. Both controls have combined to enhance water clarity in Lake Michigan. Lake Ontario has already exhibited the effects of nutrient controls and may be on the verge of manifesting food web controls. Research and monitoring recommendations to elucidate the effects of nutrient and food web controls include the following: (1) water quality and fisheries agencies must coordinate monitoring activities, standardize techniques, and establish and maintain long-term data sets to evaluate the effects of water quality and fisheries programs separately and together; (2) controlled, mesoscale, whole-system experiments should be performed to quantify rates (e.g. growth, predation, etc.) of food web interactions; and (3) the scientific community should promote research which quantifies the impact of changes in food web dynamics on changes in toxic substance levels in Great Lakes fishes.
Coastal Wetlands of Three Canadian Great Lakes: Inventory, Current Conservation Initiatives, and Patterns of Variation
Authors: Smith P. G. R. , Glooschenko V. , Hagen D. A.
Published: May 2008

The decline of wetlands, including those in the Great Lakes coastal zone, prompted the Government of Ontario to initiate steps towards a wetland management policy in 1981. Wetland inventory and evaluation in southern Ontario began in 1983. To date, 1982 wetlands have been evaluated totalling 390 000 ha. These include 160 coastal wetlands, 64 of these on Lake Ontario and the remainder on the other Great Lakes and connecting channels. Current wetland conservation initiatives are outlined including the Wetlands Planning Policy Statement and Conservation Lands Act. Although the values of Ontario's coastal wetland areas are increasingly being recognized, there has been no comprehensive study to show patterns in coastal wetland ecology. Aided by analysis of variance, ordination, and cluster analysis, we show patterns of variation in wetland and site types, soils, dissolved solids, vegetation complexity, and rare flora and fauna which differ between wetlands along Lakes Ontario, Huron, Erie, St. Clair, and connecting channels. Wetlands of Lake Huron reflect a more northern species composition, less organic soil, and more swamp and fen habitat. Along Lakes Erie, Ontario, and St. Clair the predominant marshes have smaller swamp components, organic soils, and considerable dissolved solids.
Ultraviolet reflectance and female mating preferences in the common kestrel (Falco tinnunculus)
Authors: Zampiga E. , Gaibani G. , Csermely D.
Published: May 2008

Previous studies revealed the importance of plumage brightness (considering only the visible spectral range) in female mate choice of common kestrels ( Falco tinnunculus L., 1758). Our study focuses on the effect of UV reflectance on female preference; we hypothesize that common kestrel females prefer males with UV-reflecting plumage and refuse, or are not attracted to, males whose plumage UV reflectance is prevented. We tested the preference of 20 captive females who were given a choice between two males, one behind a UV-transmitting (UV+) filter and another one behind a UV-blocking (UV–) filter. Female preference was measured as frequency and duration of visits to either male, specifically by sitting on the perch or hanging on to the partition wall. Females visited the male behind the UV+ filter more often than the male behind the UV– filter, indicating that females prefer males with UV-reflecting plumage than males without UV reflection. UV plumage and skin reflectance could provide females with information regarding current male conditions more so than other colours and other morphological parameters.
Morphological and physiological aspects of takeoff aptitudes of female common eiders (Somateria mollissima) during the pre-laying period
Authors: Ouellet J.-F. , Guillemette M. , Blier P. U.
Published: May 2008

In many bird species, follicular growth and the accumulation of body reserves may impair flight takeoff capability of breeding females. The pre-laying period in common eiders, Somateria mollissima (L., 1758), is characterized by a dramatic sex-specific takeoff impairment, and we tested the hypothesis that pre-laying female common eiders compensate to diminish or delay their takeoff impairment. We addressed our question at three organizational levels: (1) measurement of wing morphology, (2) mass of flight musculature, and (3) measurement of the activity of key enzymes of aerobic and glycolytic capacity in one locomotor muscle and one structural muscle. All measurements were performed on individuals of both sexes. We found that wing area was similar between sexes despite males being structurally larger. Our results also indicate that female mass gain is partly compensated by higher pectoralis mass, while the catalytic capacity of the tissue remains unchanged. We conclude that females diminish and delay their takeoff impairment differently according to organizational levels.
Life cycle and sexual mode adaptations of the parasitic mite Ensliniella parasitica (Acari: Winterschmidtiidae) to its host, the eumenine wasp Allodynerus delphinalis (Hymenoptera: Vespidae)
Authors: Okabe K. , Makino S.
Published: May 2008

We investigated two important life-history traits in parasites, i.e., life cycle and reproductive mode, that should be adapted to specific hosts using the parasitic mite Ensliniella parasitica Vitzthum, 1925 and the host wasp Allodynerus delphinalis (Giraud, 1866) in field- and laboratory-reared nests. The life cycle of E. parasitica was synchronized with that of the wasp; this synchronization facilitated dispersal. Life-cycle plasticity of the mite was low and development was halted on dead hosts. There was no significant difference in wasp juvenile mortality between mite-laden and mite-free individuals under controlled conditions. Therefore, the mites were suggested to be not toxic to the hosts. We confirmed for the first time that virgin female mites ovoviviparously produce arrhenotokous males the size of a protonymph to compensate for the absence of males in a cell. Although no obvious antagonistic behaviour between large (i.e., sexual) and small males was observed, large males mounted females on late prepupal hosts, about 1–2 days before either the egg or the small male was laid. We conclude that the adaptations of the mite to its host involve life-cycle synchronization, low-impact parasitism, and facultative parthenogenesis.
Feeding ecology of polymorphic larval barred tiger salamanders in playas of the Southern Great Plains
Authors: Ghioca-Robrecht D. M. , Smith L. M.
Published: May 2008

In playas of the Southern Great Plains, larval barred tiger salamanders ( Ambystoma tigrinum mavortium Baird, 1850) (= Ambystoma mavortium mavortium ) are present as polymorphic populations. Typical and cannibal morphs have been previously investigated but intermediate forms have received little attention and their role in playa food web structure is unknown. We investigated the diet composition of these three morphotypes and compared diet preferences of typical versus nontypical morphs. Typical and intermediate morphs had similar body morphology (snout to vent length and stomach content mass), but cannibal morphs had larger stomach content mass than the other morphotypes. However, the intermediate morph had a distinctive diet composition from cannibal and typical individuals as determined by diet composition rankings, diet overlap and similarity indices, and diet diversity. By comparing prey availability versus consumption, we determined that nontypical morphs preferred larger invertebrates such as tadpole shrimps (Triopsidae) and fairy shrimps (Streptocephalidae), whereas typical morphs preferred smaller prey taxa like ostracods (Cyprididae) and water boatmen (Corixidae). Several prey taxa were avoided by all larvae suggesting that feeding in A. t. mavortium in playas is not opportunistic. Our study demonstrates that larval A. t. mavortium are present not only as dimorphic but also as polymorphic populations in playas and indicates that identifying these morphs is essential for the proper understanding of aquatic food webs.
Age estimation for young bowhead whales (Balaena mysticetus) using annual baleen growth increments
Authors: Lubetkin S. C. , Zeh J. E. , Rosa C. , George J. C.
Published: May 2008

We compiled age estimates and baleen plate δ13C data from 86 bowhead whales ( Balaena mysticetus L., 1758). We used previous whale age estimates based on aspartic acid racemization (AAR) and corpora counts to extend the use of δ13C data for age determination from cycle counting to a modified exponential model using annual baleen growth increments. Our approach used the growth increment data from individual whales in a nonlinear mixed effects model to assess both population-level and whale-specific growth parameters. Although age estimates from baleen-based models become less precise as the whales age, and baleen growth and length near steady state, the growth increment model shows promise in estimating ages of bowhead whales 10–13.5 m long with baleen lengths <250 cm, where other techniques are less precise or the data are scarce. Ages estimated using the growth increment data from such whales ranged from 6.4 to 19.8 years.
A STUDY ON STEPWISE OPTIMIZATION OF FORMING PARAMETERS FOR THIN-WALLED TUBE NC BENDING
Authors: XU JIE , YANG HE , ZHAN MEI , LI HENG
Published: May 2008

The optimization design of forming parameters for thin-walled tube NC bending is a complicated problem with multi-objectives, multi-variables and multi-constraints. A stepwise optimizing strategy is proposed to solve the problem. Initial values are determined according to the databases and expert knowledge, and then the forming parameters are optimized by adopting diverse methods after reducing their range gradually. The optimization processes implementing the strategy are carried out for the bending of stainless steel and aluminum alloy tubes with thickness of 1 mm, outside diameter of 38 mm, and bending radius of 57 mm. The FEM model established by ABAQUS/Explicit is used. Free wrinkling, the allowed cross-section distortion degree and other engineering demands are constraint conditions, and the minimum wall thinning ratio is defined as the optimization objective. The optimal values of the number of mandrel balls and the clearance between mandrel balls are obtained step by step respectively. Then the mandrel extension length and the boosting velocity of the pressure die are optimized by the complex method. The experiments are performed to verify the optimization results.
A STUDY ON NON-MANDREL DRAWING PROCESS OF A RECTANGULAR TUBE FROM CIRCULAR CROSS-SECTION
Authors: QUAN G. Z. , ZHOU J. , MEN Z. X. , TONG Y.
Published: May 2008

Non-mandrel drawing process is available for producing aluminum tube with rectangular cross-section. The corresponding dynamics and finite element models were developed based on FEM software during the investigation. The influence curve of different semi-die angle on drawing load was achieved, and a proper value a2 = 11° was found. When tube blank instability occurred during drawing, the stress along the section profile increased substantially. Thus the drawing die sizing section got optimized with β = 178° to prevent blank instability. Then the touch-stress distribution of three key points was evaluated for selecting proper lubricant. Finally, the tube drawing experiments were performed to verify the effectiveness of the appropriate die.
DESIGN AND OPTIMIZATION OF TOOTH PROFILE IN THREE-SCREW PUMP
Authors: TANG QIAN , XU JIE , ZHU CAICHAO , FANG ZHIYONG , GAO ZHAN
Published: May 2008

The three-screw pump holds the merits of simple and compact configuration – small volume, high ability of self-priming, smooth working, long life span, easy disassembly, low vibration, no pressure fluctuation and noise. It has been widely used in hydraulic driven device. The three-screw pump's tooth profile directly influence its performance with features like leak tightness, wear-resistant, transmission ability and processing property. This thesis analyzes the three-screw pump's configuration and transmission theory, researches how to design its geometry parameters, and designs and optimizes its main and driven screw's tooth profile curves. At the same time, a 3D model of the main screw and driven screws are established, and their interference phenomena are checked to validate that the design is correct.
PORT-BASED DESCRIPTION OF FUNCTIONAL MODELING FOR PRODUCT CONCEPTUAL DESIGN
Authors: CAO D. X. , JIA Q. L. , HAN Y. H. , CUI C. X.
Published: May 2008

This paper introduces an approach to a port-based functional modeling framework for product conceptual design. A port-based knowledge building process is described for functional modeling. This research proposes a method of creating and managing different ports. First, this paper describes port attributes and three port types — mechanical port, electrical port and configuration port, and gives port attributes of compatibility. Second, it presents a port-based modeling design process, that is divided into three main modules: the language of port description, port-based FBS representation and port knowledge management. Three knowledge layers are specialized for function, behavior and structural knowledge. They represent different abstraction levels of the product conceptualization. Each layer is represented with a description logic for convenient reasoning. We provide formal definitions of the framework to manage port knowledge. Finally, the process of port-based functional modeling is presented in a thermal bubble jet application to demonstrate the effectiveness of the research.
STUDY ON TRIBOLOGICAL BEHAVIOR OF WATER-LUBRICATED BEARINGS
Authors: HUA XIJIN , WANG JIAXU , ZHU JUANJUAN , LIU WEN JI
Published: May 2008

Water-lubricated compound rubber bearings make use of new engineering complex material to replace precious metal as frictional pairs, and natural water to replace mineral oil as lubricant. They enable energy conservation and are environmental friendly and can be widely applied in many engineering fields such as shipping, machinery, petroleum industry, chemical industry, water conservancy, agriculture mining, etc. Experimental research, in which friction coefficient and wear extent act as performance index, was operated for different thickness, hardness and filler content of compound rubber in this paper. Effect of surface deformation and filler content on lubricating property of water-lubricated compound bearing was explored sufficiently. The experimental results indicate that friction coefficient decreases with increasing thickness of compound rubber; friction coefficient has augmented trend with increasing hardness of compound rubber; friction coefficient and wear extent have decreased trend when filler content increases; with the increase of short fiber content, friction coefficient increases but wear extent decreases. The work offers theoretical argument for technological design and practical application of compound rubber bearing.
EFFECTS OF MATERIAL ANISOTROPY AND PROCESS PARAMETERS ON THE EARING DURING CYLINDRICAL DEEP DRAWING PROCESS
Authors: YANG TUNG-SHENG , SHYU RUEY-FANG
Published: May 2008

Deep drawing process is very useful in industrial field because of its efficiency. The earing of deep drawing process is affected by many material and process parameters, such as the strain-hardening exponent, anisotropic property of blank, blank holder force, the profile radius of die, etc. In this paper, the material anisotropy and process parameters effect on the earing are investigated.
ANALYSIS AND EMPIRICAL STUDY ON THE IMPETUS AND RESISTANCE OF BPR BASED ON A MECHANICAL DYNAMICS MODEL
Authors: YI SHU PING , WANG TING , WANG YI , YU DE HAI
Published: May 2008

This paper provides concrete support for business process reengineering (BPR) related decision-making, through analysis of the mechanism of impetus and resistance. We categorize the impetus and resistance according to their domains. We then construct a dynamic model of BPR by using the principles and methods of systems analysis, in conjunction with the theory of mechanical dynamics. On this basis, dynamics analysis of the two forces was carried out and the mechanism of effect was also discussed. In the case study, experimental analysis of BPR in CF Company was carried out with the proposed model. The results showed that the model is applied to analyze the impetus and resistance in BPR as important input into the decision-making for BPR, thus compelling to implement BPR for the enterprise.
FAULT DIAGNOSIS IN A PROCESS EXPERIMENTAL CONTROL SYSTEM WITH UNKNOWN FACTORS
Authors: INOUE AKIRA , DENG MINGCONG
Published: May 2008

A fault detection problem in a process control experimental system with unknown factors is presented in this paper. The fault detecting method is based on blind system identification approach. The experimental system actuator output includes unknown dynamics and unknown fault signal. By using the fault detecting method, the fault signal is detected. Simulation results for the experimental process are presented to show the effectiveness.
INVESTIGATION OF LOAD ADAPTED GEARS AND SHAFTS MANUFACTURED BY COMPOUND-FORGING
Authors: BEHRENS BERND-ARNO , BISTRON MARCUS , KUEPER ARMIN , MOEHWALD KAI
Published: May 2008

The demand for economic processes concerning manufacturing technology, cycle time and material properties has led to the development of near net-shape techniques. Precision forging is a well-known manufacturing technology to achieve high output rates. An approach of optimization concerning the part material to produce load-adapted material properties is the so-called compound-forging. Therefore, two different alloys are forge-welded together. Non-tempering and tempering steels are used to compound-forge gears with a hard and wear-resistant surface layer as well as a ductile bulk material. Compound-forging was developed to forge spur gears and shall now be introduced to manufacture helical gears and shafts. For the production of gears and shafts billets made from non-tempering steels are forge-welded together with billets consisting of tempering steels by precision forging as well as indirect impact extrusion. In this paper, the comparison of the material properties of compound-forged gear wheels and shafts with a hard and wear resistant surface layer and a ductile bulk material is given. Mechanical properties as well as the micro-structure of the parts were investigated. The results of the investigations show a load-adapted material distribution of forge-welded materials for the production of gears and shafts.
ENHANCED REALIZATION PROBABILITY SEARCH
Authors: WINANDS MARK H. M. , BJÖRNSSON YNGVI
Published: May 2008

In this paper, we show that Realization Probability Search (RPS) significantly improves the playing strength of a world-class Lines-of-Action (LOA) computer program, even when used in combination with existing state-of-the-art αβ search enhancements. In a 600-game match, a RPS-based version of the program defeats the original one with a winning score of 62.5%. The main contribution of the paper, however, is the introduction of a much improved variant of RPS, called Enhanced Realization Probability Search (ERPS). The new algorithm addresses two weaknesses of RPS and overcomes them by using a better focussed re-searching scheme, resulting in both more robust tactical play and reduced search overhead. Our experiments in the domain of LOA show that ERPS offers just as a significant improvement over regular RPS, as the latter improves upon regular search. More specifically, the ERPS-based variant scores 62.1% against the RPS variant, and an impressive 72.2% score against the original program. This represents an improvement of over 100 ELO points over the original state-of-the-art player.
A NEW NEUTROSOPHIC APPROACH TO IMAGE THRESHOLDING
Authors: CHENG H. D. , GUO YANHUI
Published: May 2008

A neutrosophic set (Ns), a part of neutrosophy theory, studies the origin, nature, and scope of neutralities, as well as their interactions with different ideational spectra. The neutrosophic set is a powerful general formal framework that has been recently proposed. However, the neutrosophic set needs to be specified from a technical point of view. We apply the neutrosophic set in image domain and define some concepts and operations for image thresholding.

The image G is transformed into Ns domain, which is described using three subsets T, I and F. The entropy in neutrosophic set is defined and employed to evaluate the indetermination. A new λ-mean operation is proposed to reduce the set's indetermination. Finally, the proposed method is employed to perform image thresholding. We have conducted experiments on a variety of images. The experimental results demonstrate that the proposed approach can select the thresholds automatically and effectively. Especially, it can process the "clean" images, the images with different kinds of noise and the images with multiple kinds of noise well without knowing the type of the noise, which is the most difficult task for image thresholding.
THE RATIONALITY OF FUZZY CHOICE FUNCTIONS
Authors: MORDESON JOHN N. , BHUTANI KIRAN R. , CLARK TERRY D.
Published: May 2008

If we assume that the preferences of a set of political actors are not cyclic, we would like to know if their collective choices are rationalizable. Given a fuzzy choice rule, do they collectively choose an alternative from the set of undominated alternatives? We consider necessary and sufficient conditions for a partially acyclic fuzzy choice function to be rationalizable. We find that certain fuzzy choice functions that satisfy conditions α and β are rationalizable. Furthermore, any fuzzy choice function that satisfies these two conditions also satisfies Arrow and Warp.
Carbon monoxide activates NF-κB via ROS generation and Akt pathways to protect against cell death of hepatocytes
Authors: Kim Hoe Suk , Loughran Patricia A. , Rao Jayashree , Billiar Timothy R. , Zuckerbraun Brian S.
Published: May 2008

Heme oxygenase overexpression or exogenous carbon monoxide (CO) protects against hepatocyte apoptosis and fulminant hepatitis. The prevention of hepatocyte apoptosis by CO has been shown to require activation of NF-κB. The purpose of these investigations was to determine the mechanism of CO-induced hepatocyte NF-κB activation and protection against apoptosis. Primary rat or mouse hepatocytes and Hep3B cells were utilized. CO exposure was performed at 250 parts per million. Main outcome measures included cell viability, reactive oxygen species (ROS) generation, and changes in the levels of the intracellular antioxidants glutathione and ascorbate. Western blotting was performed for phospho-Akt, total Akt, and IκBα. NF-κB activation was determined by electrophoretic mobility shift assay and luciferase reporter assays. We found that CO treatment of hepatocytes prevents spontaneous apoptosis and leads to an increase in ROS production in association with Akt phosphorylation and IκB degradation. CO did not increase ROS production in respiration-deficient (ρ0) Hep3B cells. Both Akt phosphorylation and IκB degradation can be inhibited by the addition of antioxidants. Furthermore, CO-induced NF-κB activation is reversed by phosphatidylinositol 3-kinase (PI3-K) inhibitor (LY294002) or antioxidants. Additionally, prevention of spontaneous hepatocyte apoptosis by CO is reversed by PI3-K inhibition and antioxidants. In conclusion, these data implicate a survival pathway of CO-induced ROS, Akt phosphorylation, and NF-κB activation in cultured hepatocytes. This pathway may prove to be important in maintenance of hepatic function in both physiological and pathophysiological conditions.
Estradiol abolishes reduction in cell death by the opioid agonist Met5-enkephalin after oxygen glucose deprivation in isolated cardiomyocytes from both sexes
Authors: Merkel Matthias J. , Liu Lijuan , Cao Zhiping , Packwood William , Hurn Patricia D. , Van Winkle Donna M.
Published: May 2008

There is evidence for differences in the response to the treatment of cardiovascular disease in men and women. In addition, there are conflicting results regarding the effectiveness of pharmacologically induced protection or ischemic preconditioning in females. We investigated whether the ability of Met5-enkephalin (ME) to reduce cell death after oxygen-glucose deprivation (OGD) is influenced by the presence of 17β-estradiol (E2) in a nitric oxide (NO)- and estrogen receptor-dependent manner. On postnatal day 7 to 8, murine cardiomyocytes from wild-type or inducible NO synthase (iNOS) knockout mice were separated by sex, isolated by collagenase digestion, cultured for 24 h, and subjected to 90 min OGD and 180 min reoxygenation at 37°C ( n = 4 to 5 replicates). Cell cultures were incubated in E2 for 15 min or 24 h before OGD. ME was used to increase cell survival. Cell death was assessed by propidium iodide. More than 300 cells were examined for each treatment. Data are presented as means ± SE. As a result, in both sexes, ME-induced cell survival was lost in the presence of E2, and the ability of ME to improve cell survival was restored after treatment with the estrogen receptor antagonist ICI-182780. Furthermore, iNOS was necessary for ME to increase cell survival following OGD in vitro. We conclude that ME-induced reduction in cell death is abolished by E2 in a sex-independent manner via activation of estrogen receptors, and this interaction is dependent on iNOS.
Effect of sleep stage on breathing in children with central hypoventilation
Authors: Huang Jingtao , Colrain Ian M. , Panitch Howard B. , Tapia Ignacio E. , Schwartz Michael S. , Samuel John , Pepe Michelle , Bandla Preetam , Bradford Ruth , Mosse Yael P. , Maris John M. , Marcus Carole L.
Published: May 2008

The early literature suggests that hypoventilation in infants with congenital central hypoventilation syndrome (CHS) is less severe during rapid eye movement (REM) than during non-REM (NREM) sleep. However, this supposition has not been rigorously tested, and subjects older than infancy have not been studied. Given the differences in anatomy, physiology, and REM sleep distribution between infants and older children, and the reduced number of limb movements during REM sleep, we hypothesized that older subjects with CHS would have more severe hypoventilation during REM than NREM sleep. Nine subjects with CHS, aged (mean ± SD) 13 ± 7 yr, were studied. Spontaneous ventilation was evaluated by briefly disconnecting the ventilator under controlled circumstances. Arousal was common, occurring in 46% of REM vs. 38% of NREM trials [not significant (NS)]. Central apnea occurred during 31% of REM and 54% of NREM trials (NS). Although minute ventilation declined precipitously during both REM and NREM trials, hypoventilation was less severe during REM (drop in minute ventilation of 65 ± 23%) than NREM (drop of 87 ± 16%, P = 0.036). Despite large changes in gas exchange during trials, there was no significant change in heart rate during either REM or NREM sleep. We conclude that older patients with CHS frequently have arousal and central apnea, in addition to hypoventilation, when breathing spontaneously during sleep. The hypoventilation in CHS is more severe during NREM than REM sleep. We speculate that this may be due to increased excitatory inputs to the respiratory system during REM sleep.
Intermittent hypoxia conditioning prevents behavioral deficit and brain oxidative stress in ethanol-withdrawn rats
Authors: Jung Marianna E. , Simpkins James W. , Wilson Andrew M. , Downey H. Fred , Mallet Robert T.
Published: May 2008

Intermittent hypoxia (IH) has been found to protect brain from ischemic injury. We investigated whether IH mitigates brain oxidative stress and behavioral deficits in rats subjected to ethanol intoxication and abrupt ethanol withdrawal (EW). The effects of IH on overt EW behavioral signs, superoxide generation, protein oxidation, and mitochondrial permeability transition pore (PTP) opening were examined. Male rats consumed dextrin or 6.5% (wt/vol) ethanol for 35 days. During the last 20 days, rats were treated with repetitive (5–8 per day), brief (5–10 min) cycles of hypoxia (9.5–10% inspired O2) separated by 4-min normoxia exposures. Cerebellum, cortex, and hippocampus were biopsied on day 35 of the diet or at 24 h of EW. Superoxide and protein carbonyl contents in tissue homogenates and absorbance decline at 540 nm in mitochondrial suspensions served as indicators of oxidative stress, protein oxidation, and PTP opening, respectively. Although IH altered neither ethanol consumption nor blood ethanol concentration, it sharply lowered the severity of EW signs including tremor, tail rigidity, and startle response. Compared with dextrin and ethanol per se, in the three brain regions, EW increased superoxide and protein carbonyl contents and accelerated PTP opening in a manner ameliorated by IH. Administration of antioxidant N-acetylcysteine throughout the IH program abrogated the reductions in EW signs and superoxide content, implicating IH-induced ROS as mediators of the salutary adaptations. We conclude that IH conditioning during chronic ethanol consumption attenuates oxidative damage to the brain and mitigates behavioral abnormalities during subsequent EW. IH-induced ROS may evoke this powerful protection.
Chromosome landmarks as tools to study the genome of Arabidopsis thaliana
Authors: Siroky J.
Published: May 2008

The model plant Arabidopsis thaliana has long been used for genetic, cellular and molecular studies. Whereas this plant was used as a model of genetics in the 1940’s, the first cytogenetic observation of A. thaliana chromosomes was published in the beginning of the 20th century. Although Arabidopsis was not originally considered to be a good plant model for cytogenetics due to smallness of its genome, the number of published chromosome studies has expanded enormously in recent years. The advent of fluorescence in situ hybridization techniques on meiotic chromosomes together with indirect immuno-fluorescence localization of key chromosomal and nuclear proteins and wide accessibility of Arabidopsis mutants have resulted in a synergistic boost in Arabidopsis cytogenetics. In comparison to other plant species, the small genome with under-represented DNA repeats together with a small number of chromosomes makes this model plant easy to comprehend for a cytologist.
Molecular cytogenetics of forest trees
Authors: Ribeiro T. , Barão A. , Viegas W. , Morais-Cecíli L.
Published: May 2008

The economic and ecological importance of forest trees, as well as their unique biological features, has recently raised the level of interest in studies on their genomes, including sequencing of the entire poplar genome. However, cytogenetic studies have not moved in parallel with developments in genomics. This is especially true for hardwood species characterized by small genomes and relatively high numbers of small chromosomes. Molecular cytogenetic studies have mainly been focused on coniferous species, owing to the larger size of their chromosomes, and have been applied exclusively for chromosome identification and comparative karyotyping in an attempt to understand genome evolution and phylogenetic relationships. In this context, rRNA genes physical mapped by FISH reveal particularly useful chromosomal landmarks with variable distribution patterns between species. Here we present a contribution of DNA markers used for chromosome analysis, which already allowed a deeper characterization and understanding of the processes underlying genome diversity of forest trees. The use of advanced cytogenetic techniques and other potential important methods for genome analysis of forest trees is also discussed.
Plant engineered minichromosomes and artificial chromosome platforms
Authors: Birchler J.A. , Yu W. , Han F.
Published: May 2008

The introduction of telomere sequences during transformation of maize will cause chromosomal truncation. This technique has been used to create minichromosomes. With the simultaneous introduction of site specific recombination cassettes, the ability to add additional genes to the newly formed engineered minichromosome becomes possible. Targeting the supernumerary B chromosome produces truncations at a very high rate and produces minichromosomes with the additional property that they can be dosage manipulated by the reintroduction of full length B chromosomes. The uses of engineered minichromosomes are discussed.
Meiosis in plants: ten years of gene discovery
Authors: Mercier R. , Grelon M.
Published: May 2008

Plants have always been at the forefront of genetic and cytogenetic studies, but it was only following the explosion of genomic tools linked to the development of Arabidopsis thaliana as a model, that the first genes involved in plant meiosis were cloned in the late 1990s. Since then, in less than 10 years, close to fifty plant meiotic genes have been functionally characterized, mainly in Arabidopsis but also in rice and maize. In this review, we give an overview of this decade of discovery, with emphasis on the strategies that have been used for meiotic gene identification. We also highlight particularly interesting breakthroughs that these mutant and gene screens made possible.
Meiotic genes and proteins in cereals
Authors: Jenkins G. , Phillips D. , Mikhailova E.I. , Timofejeva L. , Jones R.N.
Published: May 2008

We review the current status of our understanding and knowledge of the genes and proteins controlling meiosis in five major cereals, rye, wheat, barley, rice and maize. For each crop, we describe the genetic and genomic infrastructure available to investigators, before considering the inventory of genes and proteins that have roles to play in this process. Emphasis is given throughout as to how translational genomic and proteomic approaches have enabled us to circumvent some of the intractable features of this important group of plants.
ASY1 coordinates early events in the plant meiotic recombination pathway
Authors: Sanchez-Moran E. , Osman K. , Higgins J.D. , Pradillo M. , Cuñado N. , Jones G.H. , Franklin F.C.H.
Published: May 2008

Meiosis is a fundamental and evolutionarily conserved process that is central to the life cycles of all sexually reproducing eukaryotes. An understanding of this process is critical to furthering research on reproduction, fertility, genetics and breeding. Plants have been used extensively in cytogenetic studies of meiosis during the last century. Until recently, our knowledge of the molecular and functional aspects of meiosis has emerged from the study of non-plant model organisms, especially budding yeast. However, the emergence of Arabidopsis thaliana as the model organism for plant molecular biology and genetics has enabled significant progress in the characterisation of key genes and proteins controlling plant meiosis. The development of molecular and cytological techniques in Arabidopsis, besides allowing investigation of the more conserved aspects of meiosis, are also providing insights into features of this complex process which may vary between organisms.This review highlights an example of this recent progress by focussing on ASY1, a meiosis-specific Arabidopsis protein which shares some similarity with the N-terminus region of the yeast axial core-associated protein, HOP1, a component of a multiprotein complex which acts as a meiosis-specific barrier to sister-chromatid repair in budding yeast. In the absence of ASY1, synapsis is interrupted and chiasma formation is dramatically reduced. ASY1 protein is initially detected during early meiotic G2 as numerous foci distributed over the chromatin. As G2 progresses the signal appears to be increasingly continuous and is closely associated with the axial elements. State-of-the-art cytogenetic techniques have revealed that initiation of recombination is synchronised with the formation of the chromosome axis. Furthermore, in the context of the developing chromosome axes, ASY1 plays a crucial role in co-ordinating the activity of a key member of the homologous recombination machinery, AtDMC1.
Inhibitory Effect of Curcumin on Corneal Neovascularization in vitro and in vivo
Authors: Bian Fang , Zhang Ming-Chang , Zhu Yun
Published: May 2008

Purpose: To examine the effect of curcumin on the proliferation and the migration of human umbilical vein endothelial cells (HUVECs) and on the corneal neovascularization in the corneal alkaline burn rat model. Methods: HUVEC proliferation, migration, and apoptosis were examined after treatment with various concentrations of curcumin. The effect of curcumin on the activation of nuclear factor-ĸB (NF-ĸB) was measured by an electrophoretic mobility shift assay (EMSA) in vivo. Corneal neovascularization was induced in vivo by an alkaline burn of the cornea in Sprague-Dawley rats. After topical drug treatments with curcumin, vascular endothelial growth factor (VEGF) was evaluated in the corneal tissue by reverse transcription polymerase chain reaction and by immunohistochemistry. Corneal neovascularization was evaluated by slit-lamp biomicroscopy. Results: Curcumin at a concentration of 40 µmol/l for 24 h significantly inhibited the growth of HUVECs. The Boyden microchamber assay showed that curcumin dramatically inhibited the migration of HUVECs at a concentration of 40 µmol/l. When TUNEL assays were performed, the number of apoptotic cells increased after treated with curcumin. The EMSA revealed that curcumin inhibits the activation of NF-ĸB in HUVECs. The expression of VEGF in the corneal tissues was inhibited by curcumin on days 7 and 14 after alkaline burn. Conclusions: Curcumin may be useful as an angiogenic inhibitor in the treatment of corneal diseases that show neovascularization.
Impact of Low Vision on Well-Being in 10 European Countries
Authors: Mojon-Azzi S.M. , Sousa-Poza A. , Mojon D.S.
Published: May 2008

Background: Because of the growing life expectancy in developed countries and the exponential increase in vision loss with increasing age, a growing number of elderly persons will eventually suffer from visual impairment and blindness. This paper describes the association between self-reported vision and well-being in individuals aged 50 years and older and their families. Methods: Using binary logistic regressions on data from the 2004 Survey of Health, Ageing and Retirement in Europe (SHARE), we analysed the association between self-reported corrected vision in general, corrected distance vision and corrected reading vision on 11 variables capturing emotional well-being, future hopes and perspectives, and concentration on daily activities. Results: For 22,486 individuals from 10 European countries, aged 64.23 ± 10.52 years, lower vision was associated with a highly significant negative impact on all measured aspects of well-being. Conclusions: These data from a large population base in Europe provide evidence that persons with low vision have a higher probability of concentration problems during reading and entertainment; losing interest and enjoyment in their activities; feeling fatigued, irritable, sad, and tearful; having less hope for the future; and wishing for death. Effective measures of early detection, prevention, rehabilitation, education and research, as well as a holistic view of a patient, could help counter these problems, thereby improving mental and physical health and reducing the economic impact of low vision.
Hormone Replacement Therapy as a Risk Factor for Non-Small Cell Lung Cancer: Results of a Case-Control Study
Authors: Ramnath N. , Menezes R.J. , Loewen G. , Dua P. , Eid F. , Alkhaddo J. , Paganelli G. , Natarajan N. , Reid M.E.
Published: May 2008

Purpose: It was the aim of this study to assess the risk of lung cancer in postmenopausal women who received hormone replacement therapy (HRT). Experimental Design: This case-control study involves women who received medical services at Roswell Park Cancer Institute (RPCI) in Buffalo, New York, between 1982 and 1998, and who agreed to complete an epidemiological questionnaire. Participants with missing smoking data were excluded. The case group consisted of 595 women with primary lung cancer. Controls included 1,195 women, randomly selected from a pool of 5,845 eligible individuals, who received medical services at RPCI for non-neoplastic conditions; they had come to RPCI with a suspicion of neoplastic disease, but were diagnosed with neither benign nor malignant conditions. Controls were frequency matched 2:1 to cases on 5-year age intervals and exposure to smoking (ever/never). Cases and controls were comparable for age (means 61.3 and 61.0 years) and ever smoking (90%). Results: There were more former smokers among the cases (67 vs. 59% in controls); cases were less likely to be high school educated, were thinner, and were less likely to report HRT use compared with controls. Overall, hormone use was associated with a significant reduction in risk of lung cancer (adjusted odds ratio = 0.67; 95% confidence interval 0.53–0.85). Stratified analyses showed significant reductions in lung cancer risk in former smokers and women with normal to low body mass index. Conclusion: This study supports the hypotheses that there is a protective effect of HRT use on lung cancer risk in women.