bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth and survival of age-0 walleye (Sander vitreus): interactions among walleye size, prey availability, predation, and abiotic factors
Authors: Hoxmeier R John H. , Wahl David H , Brooks Ronald C , Heidinger Roy C
Published: October 2006

We examined the importance of prey availability, predation, and abiotic factors in determining growth and survival of age-0 walleye (Sander vitreus) across 15 Illinois reservoirs during 7 years. Multiple life stages were examined by stocking walleye at three different size groups: larval (6 mm total length (TL)), small (46 mm TL), and large (100 mm TL). Factors affecting growth and survival of walleye varied depending on walleye size. Growth of small and large walleye increased with benthic invertebrate density. Temperature had a positive effect on larval and small walleye growth but a negative effect on large walleye growth. Prey availability was an important factor for walleye survival across all size groups, whereas temperature affected only larval and large walleye. Juvenile centrarchid density had a negative effect on larval walleye survival, presumably caused by predation. Our best predictive models explained substantial variation in survival for larval (97%), small (57%), and large (83%) walleye. We also explained a high proportion of variation in growth of large (98%), small (55%), and larval (52%) walleye. Our study demonstrates the importance of examining multiple life stages to predict growth and survival and leads to a better understanding of walleye recruitment and recommendations for stocking strategies.
First-year growth and recruitment of coastal largemouth bass (Micropterus salmoides): spatial patterns unresolved by critical periods along a salinity gradient
Authors: Peer Adam C , DeVries Dennis R , Wright Russell A
Published: October 2006

Although critical periods often explain first-year growth and recruitment patterns of young fishes, isolated subpopulations in spatially heterogeneous environments can be influenced by distinct factors, preventing critical periods from explaining growth and recruitment for the overall population. When we explored first-year growth and recruitment variability of largemouth bass (Micropterus salmoides) along an upstream–downstream gradient in the Mobile–Tensaw Delta, Alabama, USA, growth was consistently faster at sites closest to or within brackish habitats in 2002 and 2003, despite different abiotic conditions between years. Energetic content of food consumed by faster-growing fish, particularly those furthest downstream, was greater than that for slower-growing fish. Although the timing of the switch to piscivory did not explain growth differences, the degree of piscivory was important. Hatch date had no influence on growth differences and consequently did not affect fall condition, overwinter survival, or age-1 recruitment. Contrary to several studies in freshwater systems at this latitude, first-winter mortality was neither size-selective nor excessive, and largemouth bass continued to grow through the winter. These results demonstrate that early growth can vary substantially among subpopulations in spatially heterogeneous environments and that these differences are not necessarily explained by the same factors thought to be important for freshwater largemouth bass populations.
Myosin expression levels and enzyme activity in juvenile spotted wolffish (Anarhichas minor) muscle: a method for monitoring growth rates
Authors: Imsland Albert K , François Nathalie R. Le , Lamarre Simon G , Ditlecadet Delphine , Sigurðsson Sindri , Foss Atle
Published: October 2006

The activity of glycolytic enzymes and the expression levels of myosin RNA was monitored in the white muscle of juvenile spotted wolffish (Anarhichas minor) reared under different temperature regimes. A group of individually tagged juvenile spotted wolffish was reared for 6 months at 4, 6, 8, and 12 °C. After the rearing trial, biopsy samples were taken from white muscle of each individual and the relationship between individual growth, enzyme activity, and myosin expression was investigated. A positive relationship between the activities of two glycolytic enzymes (pyruvate kinase and lactate dehydrogenase) and individual growth rate was observed. Using real-time polymerase chain reaction (PCR) and specially developed primers for myosin mRNA and 18S rRNA for spotted wolffish, we were able to detect differences in the relative myosin expression between experimental groups, and a positive relationship between myosin expression and specific growth rates was observed. These methods may be useful as an indicator of growth rate in wild fish and a fast and reliable indicator of growth potential under culture conditions. The method also has the potential to measure differences in white muscle synthesis in fish reared under variable environmental parameters and during different life history stages.
Response of the residential piscivorous fish community to introduction of a new predator type in a mesotrophic lake
Authors: Schulze Torsten , Baade Ulrich , Dörner Hendrik , Eckmann Reiner , Haertel-Borer Susanne S , Hölker Franz , Mehner Thomas
Published: October 2006

Although the effects of introduced predators on prey populations in aquatic ecosystems have been studied frequently, less is known about the interactions between predators. We performed a whole-lake experiment by stocking a non-native top predator (pikeperch (Sander lucioperca)) to two residential piscivores (Eurasian perch (Perca fluviatilis) and northern pike (Esox lucius)). By analyzing spatial distribution, diet composition, growth, and consumption rates of the piscivores before and after pikeperch introduction, we tested how both density-dependent and trait-mediated responses affected interactions between the three predators. Total piscivore biomass increased 1.5 times and annual consumption by the piscivores increased 1.7 times after stocking, attributable to the stocked pikeperch and increased northern pike abundances. Abundance, distribution, and consumption data indicated that northern pike was hardly affected by pikeperch stocking and even increased its biomass, whereas piscivorous perch shifted its habitat use towards the littoral lake areas in response to competition with pikeperch. Furthermore, all piscivores increasingly fed on small perch. The forced habitat shift of piscivorous perch in combination with increased predation on small perch led to a decreased abundance of large perch, attributable to the compensatory effects of intraguild predation and cannibalism.
Baseline expression of heat-shock proteins (HSPs) of a "thermotolerant" Mediterranean marine species largely influenced by natural temperature fluctuations
Authors: Lejeusne Christophe , Pérez Thierry , Sarrazin Vanessa , Chevaldonné Pierre
Published: October 2006

Northwestern Mediterranean warming-related disease outbreaks and species shifts have recently been documented. Biomarkers of short-term effects on the health or resistance of organisms are necessary to assess and understand mechanisms affecting marine biodiversity. Heat-shock protein (HSP) expression was here believed to present finer variations than previously reported in experimental studies, which we tested to assess HSP sensitivity and relevance in the global warming context. One population of the "thermophilic" marine cave mysid Hemimysis margalefi was monitored over 4 years. Three HSPs presented recurrent expression. Among them, HSP50 and HSP60 expressions varied seasonally with environmental temperature. HSP60 expression displayed the greatest variability and was most closely related to temperature fluctuations. Multiple regression showed that while the main stressor was temperature, demographic variables (proportion of immatures, proportion of gravid females) also influenced expression variability. Such a monitoring of HSP baseline expression in a natural population had only rarely been conducted. HSPs are, however, good biomarkers to evaluate the effects of warming episodes or heat stress in the wild. This study provides essential spatial and temporal reference for further experimental and in situ analyses and is a prerequisite to diagnostic and predictive approaches.
Effects on periphyton and macroinvertebrates from removal of submerged wood in three Ontario lakes
Authors: Smokorowski Karen E , Pratt Thomas C , Cole William G , McEachern Laurie J , Mallory Elaine C
Published: October 2006

We removed 40%–70% of nearshore wood habitat from three lakes to test the link between habitat and productive capacity, specifically focusing on the provision of substrate for periphyton and invertebrate production by submerged wood. Our objectives were fourfold: (i) to calculate the total amount of invertebrate and periphyton biomass removed with the wood; (ii) to explore wood's value as habitat for invertebrates and periphyton; (iii) to determine the response within residual epixylic periphyton and invertebrate biomass; and (iv) to assess interactions between periphyton and invertebrates and other factors that may influence wood's productivity. Invertebrate biomass was greater on wood than in sediment, but the total available sediment area exceeded that of wood, thus a relatively small proportion of overall productivity was lost. Highly decayed wood supported greater chlorophyll a concentrations and more invertebrate biomass and diversity than fresh wood. The removal had no measurable effect on whole-lake water chemistry, nor did it result in a response in residual epixylic periphyton and invertebrate biomass. We conclude that we permanently reduced a dynamic and concentrated biomass of primary and secondary productivity in lakes by removing submerged wood habitat.
Variation in the response of crustacean zooplankton species richness and composition to the invasive predator Bythotrephes longimanus
Authors: Strecker Angela L , Arnott Shelley E , Yan Norman D , Girard Robert
Published: October 2006

The predacious invertebrate Bythotrephes longimanus has now invaded >90 freshwater lakes in North America. There is some evidence that B. longimanus has a negative effect on summer zooplankton species richness; however, no study has examined the effect of B. longimanus throughout the ice-free season in more than one lake. We visited 10 invaded and 4 reference lakes every 2 weeks from May to September, collecting B. longimanus, crustacean zooplankton, and water chemistry samples. Composite samples were pooled across the study season for each lake. Bythotrephes longimanus significantly reduced cladoceran species richness, diversity, and abundance, and the total zooplankton community also exhibited decreased richness, diversity, and abundance. Seasonal sampling was better than synoptic surveys at detecting changes in abundance, but richness estimates were similar. As B. longimanus continues to spread across lake landscapes, we expect it will have profound impacts on local and regional richness and species distribution patterns.
Sperm quality influences male fertilization success in walleye (Sander vitreus)
Authors: Casselman Stephen J , Schulte-Hostedde Albrecht I , Montgomerie Robert
Published: October 2006

We examined how variation in sperm quality influences a male's success at fertilizing ova (male fertilization success) in a wild population of walleye (Sander vitreus). To do this, we conducted controlled fertilization trials using milt and eggs (ova) from wild-spawning fish and measured male fertilization success (percentage of ova fertilized) by examining eggs after 24 h of incubation. We found that both the number of sperm and sperm swimming speed (at 10 s after activation) were significantly related to fertilization success. There was, with respect to fertilization success, a relatively large return on male investment in the number of sperm, but this return diminished as the percentage of ova fertilized increased above 50%. This is in agreement with theoretical predictions based on external fertilization dynamics. When the number of sperm used in the experimental trials was kept constant, variation in sperm swimming speed (at 10 s after activation) explained approximately 90% of the variation in a male's fertilization success. These findings demonstrate that the variation in sperm quality found in wild spawning populations has the potential to dramatically influence male reproductive success.
Consequences of inappropriate criteria for accepting age estimates from otoliths, with a case study for a long-lived tropical reef fish
Authors: Marriott Ross J , Mapstone Bruce D
Published: October 2006

Fish ages estimated from increments in otoliths are uncertain because of various sources of error, including increment interpretation. Interpretation error is often addressed by reading each otolith multiple times and accepting age estimates only if readings satisfy certain consistency criteria. Choice of an inappropriate acceptance criterion may significantly bias the accepted age estimates and derived parameters such as mortality. The frequencies and magnitudes of discrepancies from replicate readings of otoliths increased with age for the red bass, Lutjanus bohar. The trend was best described by a constant probability of misinterpreting each increment, indicating an age acceptance criterion that allowed for increasing discrepancy between readings with age. Simulations of three error processes in reading otoliths, two processes of error accumulation within readings, and six acceptance criteria illustrated the biases in age-based metrics that arise from choosing inappropriate acceptance criteria. Biases were largest for static constant, rather than proportional, acceptance criteria, leading to elevated exclusion of older otoliths, overestimation of mortality, and underestimation of mean age. von Bertalanffy growth parameters were generally estimated with little bias. We recommend formal analysis of alternative models of ageing error to choose appropriate acceptance criteria and minimise biases in age-based demographic metrics.
Recruitment variability in Baltic Sea sprat (Sprattus sprattus) is tightly coupled to temperature and transport patterns affecting the larval and early juvenile stages
Authors: Baumann H , Hinrichsen H -H , Möllmann C , Köster F W , Malzahn A M , Temming A
Published: October 2006

Recruitment patterns of Baltic Sea sprat (Sprattus sprattus) were correlated to time series of (i) month- and depth-specific temperature conditions and (ii) larval drift patterns inferred from long-term Lagrangian particle simulations. From the latter, we derived an index that likely reflected the variable degree of annual larval transport from the central, deep spawning basins to the shallow coastal areas of the Baltic Sea. The drift index was significantly (P < 0.001) correlated to sprat recruitment success and explained, together with sprat spawning stock biomass, 82% of the overall variability between 1979 and 2003. Years of strong larval displacement towards southern and eastern Baltic coasts corresponded to relative recruitment failure, while years of retention within the deep basins were associated with relative recruitment success. The strongest correlation between temperature and recruitment occurred during August in surface waters, explaining 73% of the overall variability. Together, the two approaches advocate that new year classes of Baltic sprat are predominantly composed of individuals born late in the season and are determined in strength mainly by processes acting during the late larval and early juvenile stages. However, prior to be included in recruitment predictions, the biological mechanisms underlying these strong correlations may need to be better resolved.
Salinity controls phytoplankton response to nutrient enrichment in the Great Salt Lake, Utah, USA
Authors: Marcarelli Amy M , Wurtsbaugh Wayne A , Griset Olivia
Published: October 2006

To examine how salinity and nutrient supply interact to control phytoplankton community composition, nutrient limitation, and dinitrogen (N2) fixation rates in the Great Salt Lake (Utah, USA), we conducted a series of bioassay experiments with plankton from both Gilbert Bay, where salinities are near 160 g·L–1, and Farmington Bay, where salinities range from 10 to 90 g·L–1. Six-day nutrient addition bioassay experiments showed that the extant phyto plankton communities in both bays were limited by nitrogen (N). However, in 28- to 30-day factorial bioassay experiments in which both salinities and nutrient supply were manipulated, phosphorus stimulated chlorophyll a as much as 500% when salinities were less than 70 g·L–1and N2-fixing cyanobacteria were present. At salinities greater than 70 g·L–1, or with additions of combined N, N2fixation ceased. When N2-fixing cyanobacteria were absent, the plankton community was routinely N-limited regardless of salinity. The results of these experiments suggest that nutrient limitation of phyto plankton communities may change depending on salinity levels, because salinity controls whether N2-fixing cyanobacteria will be present in the phytoplankton community. Therefore, both salinity and nutrient supply must be considered when making water quality decisions for hypersaline systems such as the Great Salt Lake.
Interannual variation in large-scale movement of Atlantic bluefin tuna (Thunnus thynnus) determined from pop-up satellite archival tags
Authors: Sibert John R , Lutcavage Molly E , Nielsen Anders , Brill Richard W , Wilson Steven G
Published: October 2006

Data from pop-up satellite archival tags (PSATs) deployed on Atlantic bluefin tuna (Thunnus thynnus) in 1999, 2000, and 2002 were analyzed synthetically using variants of a state–space statistical model to estimate tag shedding positions, in situ position estimation errors, and movement parameters. Geographic position estimates were computed from PSAT data for 30% to 50% of the days at liberty for each tag. Such relatively low position reporting rates may present biased impressions of movement for brief times at liberty. The respective longitude and latitude errors were estimated by the state–space Kalman filter model to be approximately 0.4° and 1.0° for the 1999 deployments, 0.4° and 2.1° for the 2000 deployments, and 0.9° and 2.1° for the 2002 deployments. Estimated movement parameters were used in stochastic simulation models to predict the distribution of tagged fish after times at liberty that exceed observed reporting dates. The distributions predicted by parameters estimated from the 2002 deployments were more restricted than those estimated from the 1999 deployments. Atlantic bluefin dispersal patterns appear to be age- or size-dependent and linked to shifts in oceanographic conditions. Future fisheries management measures should address interannual differences in stock distribution identified by electronic tags.
A model for evaluating fishing impacts on habitat and comparing fishing closure strategies
Authors: Fujioka Jeffrey T
Published: October 2006

In response to increasing concern with the effects of fishing on benthic habitat, I show a mathematical model using state transition equations to compute habitat reduction by unifying the processes of fishing impact and habitat recovery. The model assumes habitat is either in an unimpacted state or in an impacted state. The state transition equations describe that fishing decreases unimpacted habitat and the recovery process decreases impacted habitat. The equations are integrated under constant fishing effort for habitat trajectories over time, and the equilibrium habitat level is derived. A difference equation is also derived to model habitat trajectories under varying fishing effort. An exploration of the joint properties of the habitat reduction and catch equations provides guidance in choosing or designing habitat protection measures. Illustrations with the model demonstrate that when harvest levels are maintained, closing heavily fished areas rather than lightly fished areas can result in increased habitat reduction.
Amount, position, and age of coarse wood influence litter decomposition in postfirePinus contortastands
Authors: Remsburg Alysa J , Turner Monica G
Published: October 2006

Spatial variation in vegetation and coarse wood is a major source of forest heterogeneity, yet little is known about how this affects ecosystem processes. In 15-year-old postfire lodgepole pine (Pinus contorta var. latifolia Englem.) stands in Yellowstone National Park, Wyoming, we investigated how the decomposition rate varies with the position of coarse wood and other dominant structures within and among stands. Tongue depressors (TD) (made of birch (Betula sp.)) and litterbags containing herbaceous litter (HL) and needle litter (NL) were deployed for 2 years within 3 burned stands and among 17 burned stands (each 0.25 ha). Within stands, the decomposition rate varied among six microsite treatments (above and below legacy wood, below logs on the ground and elevated logs, below saplings, and on open soil). Two-year mean mass loss from all litter types was least under elevated logs (HL 34.0%, NL 8.6%, TD 3.5%) and greatest under legacy wood (HL 55%, NL 33%, TD 12%). The moisture level was consistently lowest under elevated logs and highest beneath logs on the ground. Among forest stands, 2-year mass losses from HL and TD were negatively related to the amount of elevated wood. The influence of coarse wood on litter decomposition at two spatial scales suggests that coarse-wood accumulation creates long-term spatial heterogeneity in carbon and nutrient cycles.
Achieving higher heritabilities through improved design and analysis of clonal trials
Authors: Gezan Salvador A , White Timothy L , Huber Dudley A
Published: October 2006

Clonal testing was studied under different environmental patterns and experimental designs through simulation with the criteria of maximizing broad-sense heritability estimates and genetic gain from clonal selection. Several experimental designs were studied together with three patterns of environmental variability. In addition, empirical 95% confidence intervals for heritability estimates were compared with Dickerson's approximate method. Other elements studied included (i) conditions under which different environmental patterns yield high or low heritabilities and (ii) effects of varying the number of ramets per clone. Row-column designs produced the highest mean individual broad- sense heritability, but these designs were only slightly more efficient than incomplete block designs with small block sizes. For all experimental designs, Dickerson's approximate method for estimating the variance of heritability estimates produced reasonable 95% confidence intervals but overestimated the upper confidence limit of complex designs. Larger heritabilities were found with higher tree-to-tree spatial correlations and lower amounts of microsite residual variance, and varying gradients had negligible influence. The effect of implementing Latinization was significant on increasing heritability, but small in practical terms, and was more important for patchy surfaces. Experiments with more ramets per clone yielded higher clonal mean heritabilities, and using between four and six ramets per clone per site is recommended.
Optimizing efficiency of height modeling for extensive forest inventories
Authors: Barrett T M
Published: October 2006

Although critical to monitoring forest ecosystems, inventories are expensive. This paper presents a generalizable method for using an integer programming model to examine tradeoffs between cost and estimation error for alternative measurement strategies in forest inventories. The method is applied to an example problem of choosing alternative height-modeling strategies for 1389 plots inventoried by field crews traveling within an 82.5 × 106 ha region of the west coast of North America during one field season. In the first part of the application, nonlinear regional height models were constructed for 38 common species using a development data set of 137 374 measured tree heights, with root mean square error varying from 6.7 to 2.1 m. In the second part of the application, alternative measurement strategies were examined using a minimal cost objective subject to constraints on travel time and estimation error. Reduced travel time for field crews can be a significant portion of the cost savings from modeling tree heights. The optimization model was used to identify a height-modeling strategy that, given assumptions made, resulted in <10% of maximum average plot volume error, >33% of potential measurement cost savings, and small bias for estimates of regional volume and associated sampling error (0.1% and 0.4%, respectively).
Influence of climate on tree rings and vessel features in red oak and white oak growing near their northern distribution limit, southwestern Quebec, Canada
Authors: Tardif J C , Conciatori F
Published: October 2006

Little is known about environmental controls on vessel features in ring-porous tree species. Our objectives were to assess (i) the association between tree-ring descriptors (vessels and width) and climate in two oak species, white oak, Quercus alba L., and red oak, Quercus rubra L., and (ii) the utility of vessel series in climate reconstruction. The study was conducted in southern Quebec and 10 trees of each species were analyzed. For each species, 11 chronologies (vessel and ring width) were developed and compared. Few differences were observed between the oak species. All vessel chronologies were associated with those of ring dimension and none revealed a unique climate signal. Current growing season conditions were mainly associated with latewood features, whereas those of the year prior to ring formation were mainly associated with earlywood features. The best climate variable to reconstruct was the July Canadian Drought Code and the best reconstruction model was derived from earlywood, latewood, and ring-width chronologies. We conclude that vessel chronologies for Q. alba and Q. rubra have limited use in dendroclimatology. Vessel features are best used to identify event years recorded during the life of a tree. Vessel series could prove useful, however, in calibrating physiologically based models of tree growth.
Beneficial influence of plant neighbours on tree growth in drained forested peatlands: a case study
Authors: Jutras Sylvain , Hökkä Hannu , Bégin Jean , Plamondon André P
Published: October 2006

In boreal forest, drainage can be successfully used to lower the water-table level of postharvest forested peatland stands suffering from watering-up. The later vegetation revival and growth is suspected to gradually create a water-table drawdown described in this study as biological drainage. Its effect on the annual stump diameter increment of planted eastern larch (Larix laricina (Du Roi) K. Koch) and naturally regenerated black spruce (Picea mariana (Mill.) BSP) was studied on a postharvested and drained forested peatland located in eastern part of the Canadian boreal forest. A factor describing the neighbourhood occupancy of every subject tree was used to illustrate biological drainage in a retrospective growth analysis. Results showed the dual effect of the neighbourhood occupancy factor: competing situations close to the ditch and growth-favouring situations farther from it. In the latter case, the studied trees demonstrated better growth with moderately increasing neighbourhood occupancy. This was interpreted as evidence of the beneficial effect of biological drainage on tree growth. The presence of speckled alder (Alnus incana subsp.rugosa (Du Roi) J. Clausen) in the neighbourhood of selected trees corresponded to improved growth for both studied species.
Antihypertensive therapy induces compartment-specific chemokine expression and a Th1 immune response in the clipped kidney of Goldblatt hypertensive rats
Authors: Steinmetz O. M. , Sadaghiani S. , Panzer U. , Krebs C. , Meyer-Schwesinger C. , Streichert T. , Fehr S. , Hamming I. , van Goor H. , Stahl R. A. K. , Wenzel U.
Published: October 2006

The present study examined the pathogenesis of interstitial inflammation and fibrosis in antihypertensively treated rats with two-kidney, one-clip hypertension. Hypertensive rats were randomized into four groups: no treatment and moderate, intermediate, and intensified lowering of blood pressure with increasing doses of a vasopeptidase inhibitor for 6 wk. The vasopeptidase inhibitor dose dependently lowered blood pressure. The tubulointerstitial damage was accompanied by a diffuse infiltration of mononuclear cells and circumscript mononuclear inflammatory cell cluster formation consisting mainly of T cells and to a lesser degree of macrophages and B cells. Real-time PCR analyses showed a dose-dependent induction of MCP-1 and the Th1-type chemokines IP10 and Mig as well as their receptor CXCR3 and the Th1 cytokine IFN-γ. In situ hybridization and laser microdissection revealed a strong expression of these Th1-associated transcripts in the clusters and, in the case of MCP-1, also diffusely in the interstitium. The inflammation was accompanied by the appearance of myofibroblasts and synthesis of the fibrogenic factor plasminogen activator inhibitor-1 as well as the collagenase matrix metalloproteinase-2, leading to collagen I upregulation and interstitial scarring. No inflammation or fibrosis was found in normotensive rats treated with the vasopeptidase inhibitor. The renal injury in the clipped kidney is accompanied by compartment-specific chemokine expression and cell cluster formation of Th1 specificity associated with upregulation of fibrogenic proteins and matrix metalloproteinases. These findings suggest that the Th1 chemokines IP10 and Mig as well as their receptor CXCR3 are potential targets for therapeutic interventions in ischemic nephropathy.
Transcriptomic analysis of the cardiac left ventricle in a rodent model of diabetic cardiomyopathy: molecular snapshot of a severe myocardial disease
Authors: Glyn-Jones Sarah , Song Sarah , Black Michael A. , Phillips Anthony R. J. , Choong Soon Y. , Cooper Garth J. S.
Published: October 2006

Heart disease is the major cause of death in diabetes, a disorder characterized by chronic hyperglycemia and cardiovascular complications. Diabetic cardiomyopathy (DCM) is increasingly recognized as a major contributor to diastolic dysfunction and heart failure in diabetes, but its molecular basis has remained obscure, in part because of its multifactorial origins. Here we employed comparative transcriptomic methods with quantitative verification of selected transcripts by reverse transcriptase quantitative PCR to characterize the molecular basis of DCM in rats with streptozotocin-induced diabetes of 16-wk duration. Diabetes caused left ventricular disease that was accompanied by significant changes in the expression of 1,614 genes, 749 of which had functions assignable by Gene Ontology classification. Genes corresponding to proteins expressed in mitochondria accounted for a disproportionate number of those whose expression was significantly modified in DCM, consistent with the idea that the mitochondrion is a key target of the pathogenic processes that cause myocardial disease in diabetes. Diabetes also induced global perturbations in the expression of genes regulating cardiac fatty acid metabolism, whose dysfunction is likely to play a key role in the promotion of oxidative stress, thereby contributing to the pathogenesis of diabetic myocardial disease. In particular, these data point to impaired regulation of mitochondrial β-oxidation as central in the mechanisms that generate DCM pathogenesis. This study provides a comprehensive molecular snapshot of the processes leading to myocardial disease in diabetes.
Metformin Is an AMP Kinase–Dependent Growth Inhibitor for Breast Cancer Cells
Authors: Zakikhani Mahvash , Dowling Ryan , Fantus I. George , Sonenberg Nahum , Pollak Michael
Published: October 2006

Recent population studies provide clues that the use of metformin may be associated with reduced incidence and improved prognosis of certain cancers. This drug is widely used in the treatment of type 2 diabetes, where it is often referred to as an “insulin sensitizer” because it not only lowers blood glucose but also reduces the hyperinsulinemia associated with insulin resistance. As insulin and insulin-like growth factors stimulate proliferation of many normal and transformed cell types, agents that facilitate signaling through these receptors would be expected to enhance proliferation. We show here that metformin acts as a growth inhibitor rather than an insulin sensitizer for epithelial cells. Breast cancer cells can be protected against metformin-induced growth inhibition by small interfering RNA against AMP kinase. This shows that AMP kinase pathway activation by metformin, recently shown to be necessary for metformin inhibition of gluconeogenesis in hepatocytes, is also involved in metformin-induced growth inhibition of epithelial cells. The growth inhibition was associated with decreased mammalian target of rapamycin and S6 kinase activation and a general decrease in mRNA translation. These results provide evidence for a mechanism that may contribute to the antineoplastic effects of metformin suggested by recent population studies and justify further work to explore potential roles for activators of AMP kinase in cancer prevention and treatment. (Cancer Res 2006; 66(21): 10269-73)
Preparing the “Soil”: The Primary Tumor Induces Vasculature Reorganization in the Sentinel Lymph Node before the Arrival of Metastatic Cancer Cells
Authors: Qian Chao-Nan , Berghuis Bree , Tsarfaty Galia , Bruch MaryBeth , Kort Eric J. , Ditlev Jon , Tsarfaty Ilan , Hudson Eric , Jackson David G. , Petillo David , Chen Jindong , Resau James H. , Teh Bin Tean
Published: October 2006

Sentinel lymph node (SLN) metastasis is the first step in the spreading of cancer in many malignancies. Tumor-reactive lymphadenopathy in SLNs has been observed for decades, but alterations of the lymphatic channels and vasculature in these nodes before the arrival of metastatic tumor cells remain unexplored. Using animal models, we show here that, before the establishment of metastasis in the SLN, there are reorganizations of the lymphatic channels and the vasculature. The node becomes a functional blood vessel–enriched and lymph vessel/sinus-enriched organ before metastasis. The enlargement of the lymph sinuses is correlated with the primary tumor weight. The newly emerged functional blood vessels develop from high endothelial venules (HEV), in which the proliferation rate of the endothelial cells is also significantly increased. Similar alterations of the HEVs are also characterized in the axillary lymph nodes from human breast cancer patients without the evidence of metastasis. These findings support the hypothesis that modification of the microenvironment for a secondary tumor (i.e., vasculature reorganization in the SLN) can be initiated by a primary tumor before and independent of the physical presence of metastatic cancer cells. (Cancer Res 2006; 66(21): 10365-76)
The high variability of subtelomeric heterochromatin and connections between nonhomologous chromosomes, suggest frequent ectopic recombination in rye meiocytes
Authors: González-García M. , González-Sánchez M. , Puertas M.J.
Published: October 2006

The position of telomeres, centromeres and subtelomeric heterochromatin (SH) has been studied by FISH in rye meiocytes. We compare the morphology of the signals from zygotene to telophase II mainly to determine differences in SH and telomere positions between plants with and without neocentromeres. Plants from two varieties were used: Paldang showing neocentromeres, and Puyo without neocentromeres but with two B chromosomes. In both varieties, at zygotene and pachytene the SH is observed forming clumps often including two or more bivalent ends. At diplotene the SH is stretched suggesting that it is close to the nuclear envelope. In these cases, the telomere signals are not stretched and lay behind the SH. Frequently, two or more bivalents are joined by conspicuous SH connections at diplotene strongly suggesting ectopic recombination. Probably as a result, differential distribution of the SH between recombinant homologues or the whole meiotic products is observed. From diplotene onwards, the large heterochromatic blocks cover the telomeres, the SH being the morphological end of the bivalents, both in plants with or without neocentromeres. The Bs are tightly associated only at the telomeric end of the long arm from diplotene to metaphase I. The high variability between homologous chromosomes and the frequent nonhomologous bindings of SH, strongly suggest that rye SH is in dynamic state and frequently changes in chromosome position during meiosis.
Novel cytogenetic finding: an unusual X;X-translocation in Mehsana buffalo (Bubalus bubalis)
Authors: Patel R.K. , Singh K.M. , Soni K.J. , Chauhan J.B.
Published: October 2006

Cytogenetic investigations of a phenotypically normal Mehsana river buffalo calf (Bubalusbubalis) revealed an XXY chromosome complement due to X;X-translocation in all screened metaphase plates. The chromosomal anomaly was identified by GTG-banding while CBG- and RBG-banding revealed two heterochromatin blocks and that one of the two X chromosomes was late replicating, respectively. The normal cytogenetic profiles of sire, dam and relatives of the calf suggest that the anomaly could have arisen spontaneously during oogenesis. This is the first report on a male river buffalo calf having an XXY chromosome complement with translocation between the two X chromosomes.
Key Features of the Human Middle Ear
Authors: Hudde Herbert , Weistenhöfer Christian
Published: October 2006

The human middle ear was investigated using a generalised circuit model which can simulate the spatial vibrations of the ossicular chain. The behaviour was observed for acoustic excitation via the normal air conduction path and for mechanic excitation due to shaking the complete temporal bone. More insight into the functionality of the middle ear was obtained by also considering abnormal conditions such as stiffenings. It turned out that the mammalian middle ear is superior to a columella ear due to its particular design. The placement of comparably heavy bones (malleus head and incus body) outside the main transmission path between the manubrium and the stapes footplate in combination with a very flexible ossicular chain creates several favourable properties.
Distortion Product Otoacoustic Emissions: A Time Domain Analysis
Authors: Duifhuis H.
Published: October 2006

Distortion product otoacoustic emissions (DPOAEs) provide relatively easily accessible external information about internal properties of the inner ear. A primary result is that the detection of normal DPOAE components is a strong indicator of normal functioning of the cochlear mechanics. The details of amplitude and phase behavior of the DPOAEs, and the development over time (DPOAE delay) are not fully understood and subject of some debate. In this paper, I would like to emphasize the view that precise time domain experiments and time domain model analysis provide a superb tool, the power of which is generally underestimated. Results are presented from a model analysis in which the primary-tone phase variation technique introduced by Whitehead et al. was employed successfully.
Round Window Stimulation with an Implantable Hearing Aid (Soundbridge®) Combined with Autogenous Reconstruction of the Auricle – A New Approach
Authors: Kiefer Jan , Arnold Wolfgang , Staudenmaier Rainer
Published: October 2006

Background: Congenital malformations of the auricle are often combined with atresia of the outer ear canal and malformations of the ossicles, representing aesthetic as well as functional deficits. Optimal treatment should therefore address both aspects equally. This report describes a new approach, combining the reconstruction of the auricle with implantation of an active middle ear hearing aid, stimulating the round window membrane. Method: A 33-year-old male patient, with bilateral ear microtia, fibrous atresia of the external ear canals and malformation of the ossicles due to Treacher Collins-Franceschetti syndrome was included in the study. In stage one, the cartilage framework of the new auricle, made of autogenous rib cartilage, was fabricated and implanted. During stage two, the auricle was elevated, a retro-auricular sulcus was formed and a Vibrant MED-EL Soundbridge® device was implanted. The transducer was coupled to the round window membrane. Results: Both functional and aesthetical results were favourable. Aided thresholds were between 15 and 30 dB in the frequency range of 0.75–6 kHz, monosyllabic word understanding at 65 dB SPL increased from 0 to 80%. Discussion: Combining aesthetic and functional rehabilitation, autogenous reconstruction of a new auricle together with the implantation of an active middle ear hearing aid, coupled to the round window membrane, is a promising new approach.
BioSTAR Evaluation STudy (BEST)
Authors: Mullen Michael J. , Hildick-Smith David , De Giovanni Joseph V. , Duke Christopher , Hillis W. Stewart , Morrison W. Lindsay , Jux Christian
Published: October 2006

Background—

The use of permanent synthetic implants to close atrial septal defects (ASD) and patent foramen ovale (PFO) has a number of limitations, including late complications and the limiting of transeptal access to the left heart should it be required for the later treatment of acquired heart disease. BioSTAR is a novel, bioabsorbable, atrial septal repair implant. This phase I pilot study evaluates the feasibility, safety, and effectiveness of BioSTAR for the first time in humans.

Methods and Results—

We conducted a prospective, open-label, multicenter clinical study in 58 patients aged 28 to 68 years who had a clinically significant ASD or PFO. Percutaneous shunt closure was undertaken with the BioSTAR septal repair implant. Successful device implantation was achieved in 57 (98%) of 58 patients. Closure at 30 days and 6 months, assessed by contrast transthoracic echocardiography, was 48 (92%) of 52 and 54 (96%) of 56, respectively. There was no evidence of a clinically significant response to the device. Transient atrial arrhythmia occurred in 5 patients after implantation. No major safety issues were observed.

Conclusions—

This study demonstrates the feasibility, safety, and effectiveness of BioSTAR for the closure of ASD and PFO in humans with a high rate of early and complete shunt closure. BioSTAR is a novel septal repair implant designed to provide biological closure of atrial-level defects using the patient’s natural healing response. Because 90% to 95% of the implant is absorbed and replaced with healthy native tissue, future access to the left atrium may be achieved.
Household Saving Rates and the Design of Public Pension Programmes: Cross–Country Evidence
Authors: Disney Richard
Published: October 2006

I argue that the offsetting effect of public pension contributions on household retirement saving depends on how closely the public pension programme imitates a private retirement saving plan (i.e. the ‘actuarial’ content of the public pension programme) — the closer the design of the programme to a private retirement saving plan, the higher the offset. I estimate the determinants of household saving rates in a cross-country panel, augmenting standard measures of public pension programme generosity and cost by indicators that proxy the actuarial component of the programme. These indicators affect saving rates as predicted.
Saving and Life Insurance Holdings at Boston University – a Unique Case Study
Authors: Bernheim B. Douglas , Berstein Solange , Gokhale Jagadeesh , Kotlikoff Laurence J.
Published: October 2006

This study examines the saving and insurance behaviour of 386 Boston University (BU) employees who volunteered to receive financial planning based on ESPlanner (Economic Security Planner) — a detailed life-cycle financial planning model developed by Economic Security Planning, Inc. Because the employees received their own financial plan, they had a strong incentive to provide full and accurate financial information. Hence, the data appear to be of particularly high quality for studying saving and life insurance decisions.

ESPlanner recommends annual levels of consumption, saving, and life insurance holdings that smooth a household's living standard through time subject to the household not exceeding its self-ascribed borrowing limit. The programme treats housing and special expenditures as ‘off-the-top’, adjusts for economies in shared living and the relative costs of raising children, makes highly detailed tax and Social Security benefit calculations, and permits users who don't want a stable living standard to specify how they'd like their living standards to change through time.

Our findings are striking. First, the correlation between ESPlanner's saving and insurance prescriptions and the actual decisions being made by BU employees is very weak in the case of saving and essentially zero in the case of life insurance. Many employees are spending far more and saving far less than they should, while others are under-spending and oversaving. The same holds for life insurance. The degree of under-insurance seems particularly acute. Almost 13 per cent of those BU spouses who are secondary earners would experience a 40 per cent or greater drop in their living standards were their spouses to pass away in the near future. Another 13 per cent would experience a 20 to 40 per cent drop. Second, planning shortcomings are as common among high-income professors with significant financial knowledge as they are among low-income staff with limited financial knowledge. Third, two thirds of BU employees are not in a position to smooth their living standards without exceeding their debt limits.
Strategies Used by Chinese Parents to Support English Language Learning
Authors: Xuesong Gao
Published: October 2006

The paper reports on parental involvement in Chinese students’ language learning which has emerged as a major finding from an interpretative enquiry into their English-learning experiences. The data confirm that Chinese parents and other family members are closely involved in the study participants’ language learning, in particular, their development as competent English learners. They are indirectly involved the participants’ development as English learners as language learning advocates, language learning facilitators, and language teachers’ collaborators. Furthermore, they are directly involved in their children’s development as language learning advisors, language learning coercers, and language learning nurturers. The findings suggest language teachers to be more proactive in establishing a school-family/teacher-parent partnership in learner development programs. Further research is also needed to support such a partnership.
Cyberspace and Child Abuse Images
Authors: Harrison Christine
Published: October 2006

This article approaches cyberspace as a socially constructed space in which gendered power relations are replicated and examines how cyberspace has been expropriated to escalate child sexual abuse and other sexual offenses. Making connections between different forms of abuse of women and children demonstrates that feminist perspectives provide an essential framework for understanding how new information and communication technologies are reinforcing attitudes that degrade and dehumanize women and children. Analyzing the relationship between gender and other oppressions challenges the hegemony of discourses that emphasize freedom and the democratizing potential of cyberspace and shows how cyberspace is a site for increased violence and exploitation of women and children.