bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple sequence-directed possibilities provide a pool of nucleosome position choices in different states of activity of a gene
Authors: Vinayachandran Vinesh , Pusarla Rama-Haritha , Bhargava Purnima
Published: April 2009

Background

Genome-wide mappings of nucleosome occupancy in different species have shown presence of well-positioned nucleosomes. While the DNA sequences may help decide their locations, the observed positions in vivo are end-results of chromatin remodeling, the state of gene activity and binding of the sequence-specific factors to the DNA, all of which influence nucleosome positions. Thus, the observed nucleosome locations in vivo do not reflect the true contribution of DNA sequence to the mapped position. Moreover, the naturally occurring nucleosome-positioning sequences are known to guide multiple translational positionings.

Results

We show that yeast SNR6, a gene transcribed by RNA polymerase III, constitutes nucleosome-positioning sequence. In the absence of a chromatin remodeler or any factor binding, the gene sequence confers a unique rotational phase to nucleosomes in the gene region, and directs assembly of several translationally positioned nucleosomes on ~1.2 kb DNA from the gene locus, including the short ~250 bp gene region. Mapping of all these gene sequence-directed nucleosome positions revealed that the array of nucleosomes in the gene upstream region occupy the same positions as those observed in vivo but the nucleosomes on the gene region can be arranged in three distinct registers. Two of these arrangements differ from each other in the position of only one nucleosome, and match with the nucleosome positions on the gene in repressed and active states in vivo, where the gene-specific factor is known to occupy the gene in both the states. The two positions are interchanged by an ATP-dependent chromatin remodeler in vivo. The third register represents the positions which block the access of the factor to the gene promoter elements.

Conclusion

On a gene locus, multiple nucleosome positions are directed by a gene sequence to provide a pool of possibilities, out of which the preferred ones are selected by the chromatin remodeler and transcription factor of the gene under different states of activity of the gene.
Type XVIII collagen degradation products in acute lung injury
Authors: Perkins Gavin D , Nathani Nazim , Richter Alex G , Park Daniel , Shyamsundar Murali , Heljasvaara Ritva , Pihlajaniemi Taina , Manji Mav , Tunnicliffe W , McAuley Danny , Gao Fang , Thickett David R
Published: April 2009

Introduction

In acute lung injury, repair of the damaged alveolar-capillary barrier is an essential part of recovery. Endostatin is a 20 to 28 kDa proteolytic fragment of the basement membrane collagen XVIII, which has been shown to inhibit angiogenesis via action on endothelial cells. We hypothesised that endostatin may have a role in inhibiting lung repair in patients with lung injury. The aims of the study were to determine if endostatin is elevated in the plasma/bronchoalveolar lavage fluid of patients with acute lung injury and ascertain whether the levels reflect the severity of injury and alveolar inflammation, and to assess if endostatin changes occur early after the injurious lung stimuli of one lung ventilation and lipopolysaccharide (LPS) challenge.

Methods

Endostatin was measured by ELISA and western blotting.

Results

Endostatin is elevated within the plasma and bronchoalveolar lavage fluid of patients with acute lung injury. Lavage endostatin reflected the degree of alveolar neutrophilia and the extent of the loss of protein selectivity of the alveolar-capillary barrier. Plasma levels of endostatin correlated with the severity of physiological derangement. Western blotting confirmed elevated type XVIII collagen precursor levels in the plasma and lavage and multiple endostatin-like fragments in the lavage of patients. One lung ventilation and LPS challenge rapidly induce increases in lung endostatin levels.

Conclusions

Endostatin may adversely affect both alveolar barrier endothelial and epithelial cells, so its presence within both the circulation and the lung may have a pathophysiological role in acute lung injury that warrants further evaluation.
Markers of collagen synthesis and degradation are increased in serum in severe sepsis: a longitudinal study of 44 patients
Authors: Gäddnäs Fiia , Koskela Marjo , Koivukangas Vesa , Risteli Juha , Oikarinen Aarne , Laurila Jouko , Saarnio Juha , Ala-Kokko Tero
Published: April 2009

Introduction

Sepsis-related multiple organ dysfunction is a common cause of death in the intensive care unit. The effect of sepsis on markers of tissue repair is only partly understood. The aim of this study was to measure markers of collagen synthesis and degradation during sepsis and investigate the association with disease severity and outcome.

Methods

Forty-four patients with severe sepsis participated in the study and 15 volunteers acted as controls. Blood samples were collected for 10 days after the first sepsis-induced organ dysfunction and after three and six months. Procollagen type I and III aminoterminal propeptides (PINP and PIIINP) and cross-linked telopeptides of type I collagen (ICTP) were measured.

Results

The PIIINP concentration was elevated in the septic patients (8.8 ug/L, 25th to 75th percentile = 6.8 to 26.0) when compared with controls (3.0 ug/L, 25th to 75th percentile = 2.7 to 3.3; P < 0.001) on day one. Maximum serum PIIINP concentrations during sepsis were higher in non-survivors compared with survivors (26.1 ug/L, 25th to 75th percentile = 18.7 to 84.3; vs. 15.1 ug/L, 25th to 75th percentile = 9.6 to 25.5; P = 0.033) and in multiple organ failure (MOF) compared with multiple organ dysfunction syndrome (MODS) (24.2 ug/L, 25th to 75th percentile = 13.4 to 48.2; vs. 8.9 ug/L, 25th to 75th percentile = 7.4 to 19.4; P = 0.002). Although the PINP values of the septic patients remained within the laboratory reference values, patients with MOF had higher values than patients with MODS (79.8, 25th to 75th percentile = 44.1 to 150.0; vs.40.4, 25th to 75th percentile = 23.6 to 99.3; P = 0.007). Day one ICTP levels were elevated in septic patients compared with the controls (19.4 ug/L, 25th to 75th percentile = 12.0 to 29.8; vs. 4.1 ug/L, 25th to 75th percentile = 3.4 to 5.0; P < 0.001).

Conclusions

Markers of collagen metabolism are increased in patients with severe sepsis and can be investigated further as markers of disease severity and outcome.
Risk stratification of early admission to the intensive care unit of patients with no major criteria of severe community-acquired pneumonia: development of an international prediction rule
Authors: Renaud Bertrand , Labarère José , Coma Eva , Santin Aline , Hayon Jan , Gurgui Mercé , Camus Nicolas , Roupie Eric , Hémery François , Hervé Jérôme , Salloum Mirna , Fine Michael J , Brun-Buisson Christian
Published: April 2009

Introduction

To identify risk factors for early (< three days) intensive care unit (ICU) admission of patients hospitalised with community-acquired pneumonia (CAP) and not requiring immediate ICU admission, and to stratify the risk of ICU admission on days 1 to 3.

Methods

Using the original data from four North American and European prospective multicentre cohort studies of patients with CAP, we derived and validated a prediction rule for ICU admission on days 1 to 3 of emergency department (ED) presentation, for patients presenting with no obvious reason for immediate ICU admission (not requiring immediate respiratory or circulatory support).

Results

A total of 6560 patients were included (4593 and 1967 in the derivation and validation cohort, respectively), 303 (4.6%) of whom were admitted to an ICU on days 1 to 3. The Risk of Early Admission to ICU index (REA-ICU index) comprised 11 criteria independently associated with ICU admission: male gender, age younger than 80 years, comorbid conditions, respiratory rate of 30 breaths/minute or higher, heart rate of 125 beats/minute or higher, multilobar infiltrate or pleural effusion, white blood cell count less than 3 or 20 G/L or above, hypoxaemia (oxygen saturation < 90% or arterial partial pressure of oxygen (PaO2) < 60 mmHg), blood urea nitrogen of 11 mmol/L or higher, pH less than 7.35 and sodium less than 130 mEq/L. The REA-ICU index stratified patients into four risk classes with a risk of ICU admission on days 1 to 3 ranging from 0.7 to 31%. The area under the curve was 0.81 (95% confidence interval (CI) = 0.78 to 0.83) in the overall population.

Conclusions

The REA-ICU index accurately stratifies the risk of ICU admission on days 1 to 3 for patients presenting to the ED with CAP and no obvious indication for immediate ICU admission and therefore may assist orientation decisions.
Evolutionary rates and centrality in the yeast gene regulatory network
Authors: Jovelin Richard , Phillips Patrick C
Published: April 2009

Background

Transcription factors play a fundamental role in regulating physiological responses and developmental processes. Here we examine the evolution of the yeast transcription factors in the context of the structure of the gene regulatory network.

Results

In contrast to previous results for the protein-protein interaction and metabolic networks, we find that the position of a gene within the transcription network affects the rate of protein evolution such that more central transcription factors tend to evolve faster. Centrality is also positively correlated with expression variability, suggesting that the higher rate of divergence among central transcription factors may be due to their role in controlling information flow and may be the result of adaptation to changing environmental conditions. Alternatively, more central transcription factors could be more buffered against environmental perturbations and, therefore, less subject to strong purifying selection. Importantly, the relationship between centrality and evolutionary rates is independent of expression level, expression variability and gene essentiality.

Conclusions

Our analysis of the transcription network highlights the role of network structure on protein evolutionary rate. Further, the effect of network centrality on nucleotide divergence is different among the metabolic, protein-protein and transcriptional networks, suggesting that the effect of gene position is dependant on the function of the specific network under study. A better understanding of how these three cellular networks interact with one another may be needed to fully examine the impact of network structure on the function and evolution of biological systems.
Regulation of Rapid Signal Transducer and Activator of Transcription-5 Phosphorylation in the Resting Cells of the Growth Plate and in the Liver by Growth Hormone and Feeding
Authors: Gevers Evelien F. , Hannah Matthew J. , Waters Michael J. , Robinson Iain C. A. F.
Published: April 2009

GH has physiological functions in many tissues, but the cellular targets for direct effects of GH remain ill defined in complex tissues such as the growth plate in which the contribution of direct vs. indirect actions of GH remains controversial. The Janus kinase (Jak)-signal transducer and activator of transcription (STAT)-5 pathway is activated by GH, so we developed a method to visualize nuclear Stat5b and phosphorylated Stat5 in single cells in response to a pulse of GH. Hep2 cells did not show a Stat5 phosphorylation (pY-Stat5) response to GH except in cells transfected to express GH receptors. ATDC5 cells express GH receptors and showed GH-induced pY-Stat5 responses, which varied with their state of chondrocyte differentiation. In vivo, Stat5b+ve nuclei were seen in the resting and prehypertrophic chondrocytes of the growth plate. After a single ip pulse of human GH or mouse GH, but not prolactin, pY-Stat5 responses were visible in cells in the resting zone and groove of Ranvier, 10–45 min later. Prehypertrophic chondrocytes showed no pY-Stat5 response to GH. GH target cells were also identified in other tissues, and a marked variability in spatiotemporal pY-Stat5 responses was evident. Endogenous hepatic pY-Stat5 was detected in mice with intact GH secretion but only during a GH pulse. Fasting and chronic exposure to GH attenuated the pY-Stat5 response to an acute GH injection. In conclusion, pY-Stat5 responses to GH vary in time and space, are sensitive to nutritional status, and may be inhibited by prior GH exposure. In the growth plate, our data provide direct in vivo support for an early role of GH to regulate the fate of immature chondrocytes.
Fibroblast Growth Factor-2 Autofeedback Regulation in Pituitary Folliculostellate TtT/GF Cells
Authors: Vlotides George , Chen Yen-Hao , Eigler Tamar , Ren Song-Guang , Melmed Shlomo
Published: April 2009

To investigate paracrine regulation of pituitary cell growth, we tested fibroblast growth factor (FGF) regulation of TtT/GF folliculostellate (FS) cells. FGF-2, and FGF-4 markedly induced cell proliferation, evidenced by induction of pituitary tumor transforming gene-1 (Pttg1) mRNA expression and percentage of cells in S phase. Signaling for FGF-2-induced FS cell proliferation was explored by specific pharmacological inhibition. A potent inhibitory effect on FGF-2 action was observed by blocking of Src tyrosine kinase with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d] pyrimidine (≥0.1 μm), followed by protein kinase C (PKC) inhibition with GF109203X. Treatment with FGF-2 (30 ng/ml; 10 min) activated phosphorylation of signal transducer and activator of transcription-3, ERK, stress-activated protein kinase/c-Jun N-terminal kinase, Akt, and focal adhesion kinase. Src inhibition with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d] pyrimidine suppressed FGF-2-induced Akt and focal adhesion kinase, indicating effects downstream of FGF-2-induced Src activation. FGF-2 also markedly induced its own mRNA expression, peaking at 2–4 h, and this effect was suppressed by Src tyrosine kinase inhibition. The PKC inhibitor GF109203X abolished FGF-2 autoinduction, indicating PKC as the primary pathway involved in FGF-2 autoregulation in these cells. In addition to pituitary FGF-2 paracrine activity on hormonally active cells, these results show an autofeedback mechanism for FGF-2 in non-hormone-secreting pituitary FS cells, inducing cell growth and its own gene expression, and mediated by Src/PKC signaling.
A Dynamic Model of Consumer Replacement Cycles in the PC Processor Industry
Authors: Gordon Brett R.
Published: April 2009

As high-tech markets mature, replacement purchases inevitably become the dominant proportion of sales. Despite the clear importance of product replacement, little empirical work examines the separate roles of adoption and replacement. A consumer's replacement decision is dynamic and driven by product obsolescence because these markets frequently undergo rapid improvements in quality and falling prices. The goal of this paper is to construct a model of consumer product replacement and to investigate the implications of replacement cycles for firms.

To this end, I develop and estimate a dynamic model of consumer demand that explicitly accounts for the replacement decision when consumers are uncertain about future price and quality. Using a unique data set from the PC processor industry, I show how to combine aggregate data on sales and product ownership to infer replacement behavior. The results reveal substantial variation in replacement behavior over time, and this heterogeneity provides an opportunity for managers to tailor their product introduction and pricing strategies to target the consumers of a particular segment that are most likely to replace in the near future.
Practice Prize Paper—PIN Optimal Distribution of Auction Vehicles System: Applying Price Forecasting, Elasticity Estimation, and Genetic Algorithms to Used-Vehicle Distribution
Authors: Du Jie , Xie Lili , Schroeder Stephan
Published: April 2009

In addition to retailing new vehicles, automotive manufacturers in the United States sell millions of vehicles through leasing and to fleet customers every year. The majority of these vehicles are returned to the automotive manufacturers at the end of the contracted term and must be “remarketed.” In 2007, about 10 million used vehicles were sold at more than 400 auctions in the United States. Large consigners face decisions every day about when, where, and at what price to offer these vehicles, which has significant financial implications for their profitability.

To address the challenges of the distribution process, Power Information Network (PIN), a division of J.D. Power and Associates, developed the PIN Optimal Distribution of Auction Vehicles System (ODAV), an automated decision optimization system that helps remarketers maximize profits through the most advantageous distribution of their auction vehicles. At the core of the system is a combination of three models that determine the distribution of the vehicles on a daily basis: a nearest neighbor linear regression model for short-term auction price forecasting; an autoregressive integrated moving average time-series analysis model for volume-price elasticity; and a genetic algorithm optimizer for vehicle distribution.

Since its launch in 2003, PIN has been providing ODAV services on a daily basis, and to date, more than two million vehicles have been distributed through this system. In this paper, we will describe the PIN ODAV System, its implementation, and the business impact by using as an example the experience with our largest client, Chrysler Group LLC.
Customer-Base Valuation in a Contractual Setting: The Perils of Ignoring Heterogeneity
Authors: Fader Peter S. , Hardie Bruce G. S.
Published: April 2009

The past few years have seen increasing interest in taking the notion of customer lifetime value (CLV) and extending it to value a customer base (with subsequent links to corporate valuation). The application of standard textbook discussions of CLV leads to calculations based on a single retention rate. However, at the cohort level, retention rates typically increase over time. It has been suggested that these observed dynamics are due, in large part, to a sorting effect in a heterogeneous population. We show that failing to recognize these dynamics yields a downward-biased estimate of the residual value of the customer base (compared to an aggregate analysis that ignores these dynamics). We also explore the implications of failing to account for retention dynamics when computing retention elasticities and find that the frequently reported values underestimate the true effect of increases in underlying retention rates in a heterogeneous world.
Optimal Referral Bonuses with Asymmetric Information: Firm-Offered and Interpersonal Incentives
Authors: Kornish Laura J. , Li Qiuping
Published: April 2009

Referral bonuses, in which an existing customer gets an in-kind or cash reward for referring a new customer, are a popular way to stimulate word of mouth. In this paper, we examine key firm decisions about such bonuses. Others have studied referral bonus programs; a key difference is that we study the role of recommendations not just in spreading awareness (as they do) but also in providing assessments. We start with the idea that people have a variety of reasons for making product recommendations, including placing a value on a friend's outcome with a product they recommend. We apply that idea in a context of asymmetric information: A customer combines his knowledge about the product and his familiarity with friends' tastes, making him more informed than the friends. Thus, the recommendation is a signal about the value of the product to the friend. In this setting, we consistently find that the greater the concern for others' outcomes, the higher the referral bonus should be, as long as the firm cannot more efficiently motivate recommendations with a lower price. Moreover, if price is the more efficient lever, the optimal bonus is zero, and the optimal price is low. We also show that greater concern tends to reduce firm profit and, in some cases, actually reduces consumer welfare as well.
Strategic Safety Stocks in Supply Chains with Evolving Forecasts
Authors: Schoenmeyr Tor , Graves Stephen C.
Published: April 2009

We examine the placement of safety stocks in a supply chain for which we have an evolving demand forecast. Under assumptions about the forecasts, the demand process, and the supply chain structure, we show that safety-stock placement for such systems is effectively equivalent to the corresponding well-studied problem for systems with stationary demand bounds and base-stock policies. Hence, we can use existing algorithms to find the optimal safety stocks. We use a case study with real data to demonstrate that there are significant benefits from the inclusion of the forecast process when determining the optimal safety stocks. We also conduct a computational experiment to explore how the placement and size of the safety stocks depend on the nature of the forecast evolution process.
Going Bunkers: The Joint Route Selection and Refueling Problem
Authors: Besbes Omar , Savin Sergei
Published: April 2009

Managing shipping vessel profitability is a central problem in marine transportation. We consider two commonly used types of vessels—“liners” (ships whose routes are fixed in advance) and “trampers” (ships for which future route components are selected based on available shipping jobs)—and formulate a vessel profit maximization problem as a stochastic dynamic program. For liner vessels, the profit maximization reduces to the problem of minimizing refueling costs over a given route subject to random fuel prices and limited vessel fuel capacity. Under mild assumptions about the stochastic dynamics of fuel prices at different ports, we provide a characterization of the structural properties of the optimal liner refueling policies. For trampers, the vessel profit maximization combines refueling decisions and route selection, which adds a combinatorial aspect to the problem. We characterize the optimal policy in special cases where prices are constant through time and do not differ across ports and prices are constant through time and differ across ports. The structure of the optimal policy in such special cases yields insights on the complexity of the problem and also guides the construction of heuristics for the general problem setting.
Circulating Calcitriol Concentrations and Total Mortality
Authors: Zittermann Armin , Schleithoff Stefanie S , Frisch Sabine , Götting Christian , Kuhn Joachim , Koertke Heinrich , Kleesiek Knut , Tenderich Gero , Koerfer Reiner
Published: April 2009

Background: Evidence is accumulating that vitamin D supplementation of patients with low 25-hydroxyvitamin D concentrations is associated with lower cardiovascular morbidity and total mortality during long-term follow-up. Little is known, however, about the effect of low concentrations of the vitamin D hormone calcitriol on total mortality. We therefore evaluated the predictive value of circulating calcitriol for midterm mortality in patients of a specialized heart center.

Methods: This prospective cohort study included 510 patients, 67.7% with heart failure (two-thirds in end stage), 64.3% hypertension, 33.7% coronary heart disease, 20.2% diabetes, and 17.3% renal failure. We followed the patients for up to 1 year after blood collection. For data analysis, the study cohort was stratified into quintiles of circulating calcitriol concentrations.

Results: Patients in the lowest calcitriol quintile were more likely to have coronary heart disease, heart failure, hypertension, diabetes, and renal failure compared to other patients. They also had low 25-hydroxyvitamin D concentrations and high concentrations of creatinine, C-reactive protein, and tumor necrosis factor α. Eighty-two patients (16.0%) died during follow-up. Probability of 1-year survival was 66.7% in the lowest calcitriol quintile, 82.2% in the second quintile, 86.7% in the intermediate quintile, 88.8% in the fourth quintile, and 96.1% in the highest quintile (P < 0.001). Discrimination between survivors and nonsurvivors was best when a cutoff value of 25 ng/L was applied (area under the ROC curve 0.72; 95% CI 0.66–0.78).

Conclusions: Decreased calcitriol levels are linked to excess midterm mortality in patients of a specialized heart center. .
Testosterone induction of prostaglandin-endoperoxide synthase 2 expression and prostaglandin F2α production in hamster Leydig cells
Authors: Matzkin María E , Gonzalez-Calvar Silvia I , Mayerhofer Artur , Calandra Ricardo S , Frungieri Mónica B
Published: April 2009

We have previously observed expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the key enzyme in the biosynthesis of prostaglandins (PGs), in reproductively active Syrian hamster Leydig cells, and reported an inhibitory role of PGF2αon hamster testicular steroidogenesis. In this study, we further investigated PTGS2 expression in hamster Leydig cells during sexual development and photoperiodic gonadal regression. Since PTGS2 is mostly expressed in pubertal and reproductively active adult hamsters with high circulating levels of LH and androgens, we studied the role of these hormones in the regulation/maintenance of testicular PTGS2/PGF2α. In active hamster Leydig cells, LH/hCG and testosterone induced PTGS2 and PGF2αproduction, and their actions were abolished by the antiandrogen bicalutamide (Bi). These results indicate that LH does not exert a direct effect on PG synthesis. Testosterone also stimulated phosphorylation of the mitogen-activated protein kinase isoforms 3/1 (MAPK3/1) within minutes and hours, but the testosterone metabolite dihydrotestosterone had no effect on PTGS2 and MAPK3/1. Because Bi and U0126, an inhibitor of the MAP kinase kinases 1 and 2 (MAP2K1/2), abolished testosterone actions on MAPK3/1 and PTGS2, our studies suggest that testosterone directly induces PTGS2/PGF2αin hamster Leydig cells via androgen receptors and a non-classical mechanism that involves MAPK3/1 activation. Since PGF2αinhibits testosterone production, it might imply the existence of a regulatory loop that is setting a brake on steroidogenesis. Thus, the androgen environment might be crucial for the regulation of testicular PG production at least during sexual development and photoperiodic variations in hamsters.
The Effect of Food Deprivation on the Cortisol Response to Crowding in Juvenile Steelhead
Authors: Ramsay Jennifer M , Feist Grant W , Schreck Carl B , Couture Ryan , O'Neil Joseph , Noakes David L G
Published: April 2009

Routine salmonid hatchery procedures include food deprivation, handling, and crowding of fish before sorting, transporting, or stocking. Although several studies have examined the effects of food deprivation or husbandry stressors on salmonid physiology, few have examined the effects of food deprivation and standard hatchery procedures, such as handling and crowding. The objective of this study was to determine whether food deprivation of juvenile steelhead (anadromous rainbow trout Oncorhynchus mykiss) affects the cortisol response to stress from low-water crowding. Plasma cortisol levels of fish held in circular fiberglass tanks at 8°C under normal daily feeding conditions were compared with levels in fish subjected to 3 d of food deprivation; both groups were held at 3.8 kg/m3 (control density). Additionally, these groups were compared with fed and food-deprived fish held at a density of 12.8 kg/m3 for 3 h (low-water crowding stressor). There was a significant increase in plasma cortisol levels of fish subjected to low-water crowding (129.9 ng/mL) relative to fish held at the control density (14.7 ng/mL), regardless of previous feeding treatment. However, for fish at a given density (control or crowded), there was no difference in cortisol levels between fed and food-deprived groups. We conclude that depriving juvenile steelhead of food does not significantly alter their cortisol response to low-water crowding. Consequently, the standard hatchery practice of withholding food before performing stressful husbandry procedures does not appear to cause additional stress or exacerbate physiological responses typically observed in steelhead after they are subjected to physical stressors.
Evaluation of Commercial Diets for First-Feeding Spring Chinook Salmon
Authors: Twibell Ronald G , Gannam Ann L , Ostrand Susan L , Holmes John S A , Poole Jeff B
Published: April 2009

In 2006, Bio-Oregon, Inc., the only commercial producer of cold-extruded moist diets (∼20–27% moisture) formulated for salmonids, announced that it would discontinue production of this diet line. One of these diets, BioDiet starter (19.5–21.5% moisture) was the primary feed used in many hatcheries that produce Chinook salmon Oncorhynchus tshawytscha. Thus, a feeding trial was conducted to identify an alternative starter diet for spring Chinook salmon. Five commercial diets were evaluated: Skretting BioVita (<10% moisture), EWOS Micro (<10% moisture), Rangen Starter (<10% moisture), Rangen Soft-Moist (14–17% moisture), and Silver Cup Soft-Moist (<13% moisture). Each dietary treatment was fed to quadruplicate groups of 200 randomly selected first-feeding fry reared in fiberglass tanks. Initial weight of the fish averaged 0.34 g/fish. The flow-through water supply was 12°C throughout the 8-week feeding trial. At the end of the study, fish fed Skretting BioVita exhibited significantly higher (P < 0.05) weight gain (3.4 g/fish) and feed efficiency (1.9 g gain/g feed) than fish fed the other diets. Fish fed Rangen Soft-Moist exhibited significantly lower (P < 0.05) weight gain (1.6 g/fish) and feed efficiency (1.2 g gain/g feed) than fish fed the other commercial diets. Survival rates were high (97–99%) and not significantly (P > 0.05) affected by dietary treatment. Carcass moisture and fat concentrations were significantly (P < 0.05) affected by the various diets. Carcass fat concentrations were significantly higher and carcass moisture concentrations were significantly lower in fish fed Skretting BioVita than in fish fed Rangen Starter, Rangen Soft-Moist, or Silver Cup Soft-Moist. Results of this study indicate that a moist starter diet is not required for rapid weight gain and high survival rates of first-feeding spring Chinook salmon.
Evaluation of Walleye Embryo Survival and Larval Viability after Iodine Treatment
Authors: Dabrowski Konrad , Ware Kyle , Jaroszewska Marta , Kwasek Karolina
Published: April 2009

Securing health and avoiding viral disease transmission are of paramount importance for stocking and management of walleyes Sander vitreus. Iodine compounds are widely used as nonselective antiviral substances; however, their adverse effects on embryo survival are less known. Our experiments investigated how maternal attributes influence the relationship between toxicity of iodine (expressed as concentrations and duration of treatment) and survival of walleyes after fertilization and during early larval growth. Eleven female and four male walleyes were collected in April 2007 from the Maumee River, Perrysburg, Ohio, and the gametes were transported unfertilized (2 h) to the laboratory. After fertilization and tannic acid treatment, embryos were exposed for 15, 30, and 180 min to iodine concentrations of 0 (control), 50, 100, 200, 400, and 800 mg/L. The calculated survival of 50% of the embryos at the eyed stage corresponded to an iodine concentration of 380 mg/L for the exposure duration of 15 min (i.e., the LD50; linear relationship). An increase in exposure time (to 30 or 180 min) significantly decreased embryo survival. Progeny from individual females varied in sensitivity to iodine treatment, particularly with respect to the high concentration (800 mg/L), but high survival in controls did not correspond to better resistance to iodine treatments. No significant differences were observed in larval walleye size or swim bladder inflation rates among various iodine exposure groups within 15 d after treatment.
Culture of Pacific White Shrimp Litopenaeus vannamei in a Mixed-Ion Solution
Authors: Parmenter K J , Bisesi J H , Young S P , Klaine S J , Atwood H L , Browdy C L , Tomasso J R
Published: April 2009

A non-sea-salt ionic solution that supports the culture of Pacific white shrimp Litopenaeus vannamei is described. Each 1-g/L solution consists of sodium chloride at a concentration of 754 mg/L, magnesium chloride at 57 mg/L, magnesium sulfate at 122 mg/L, potassium chloride at 16 mg/L, calcium chloride at 46 mg/L, and sodium bicarbonate at 6 mg/L. Shrimp cultured in a 15-g/L concentration of this solution for 42 d demonstrated survival, growth, total harvest weight, and feed conversion ratios similar to those of shrimp cultured in 15-g/L seawater. The results of this study may be useful for the development of marine shrimp culture in inland facilities.
Estrutura de relacionamento entre instituições de pesquisa do campo de Ciência e Tecnologia no Brasil
Authors: Rossoni Luciano , Hocayen-da-Silva Antônio João , Ferreira Júnior Israel
Published: April 2009

Neste estudo, mapeamos a estrutura de relacionamento entre instituições de pesquisa no campo de Ciência e Tecnologia no Brasil, analisando 688 artigos publicados no Enanpad e no Simpósio de Gestão da Inovação Tecnológica, entre 2000 e 2005. Com base em co-autoria, verificamos que o campo se configura como uma grande rede em que mais da metade das instituições está conectada, criando capital social. Ainda, algumas destacam-se por apresentar grande número de colaboradores, por serem pontes entre diferentes grupos e por manterem a durabilidade das relações, havendo indícios de homofilia, cujas localização geográfica e papel institucional condicionam as relações entre pares. Por fim, existe influência da cooperação na produtividade das instituições.
Influência do óleo de Copaifera langsdorffii no reparo de ferida cirúrgica em presença de corpo estranho
Authors: Vieira Rafael C. , Bombardiere Ethiane , Oliveira Julierme J. , Lino-Júnior Ruy S. , Brito Luiz A.B. , Junqueira-Kipnis Ana P.
Published: April 2009

A Copaifera langsdorffii é uma leguminosa nativa do Brasil, da qual pode ser extraído um óleo, popularmente conhecido como óleo de copaíba. Este óleo é amplamente utilizado para tratamento de feridas cutâneas por ser reconhecido como antiinflamatório e cicatrizante. Apesar disso, poucas comprovações científicas do verdadeiro efeito terapêutico desta planta medicinal foram produzidas. O objetivo desse trabalho foi avaliar o efeito do tratamento tópico com C. langsdorffii no processo de reparo quando um corpo estranho é o indutor da inflamação. Para isso, 60 camundongos da linhagem BALB/c foram submetidos à incisão cirúrgica linear de 1cm no dorso para realizar o implante de uma lamínula de vidro com 12mm de diâmetro no tecido subcutâneo. Quatro tratamentos para a ferida foram estabelecidos: controle (C) tratado com solução salina estéril, controle veículo (CV) tratado com óleo mineral estéril, tratamento 1 (T1) tratado com diluição (v:v) de óleo mineral estéril e óleo de C. langsdorffii, tratamento 2 (T2) tratado com óleo de C. langsdorffii puro. As avaliações foram realizadas em períodos de tempo pré-determinados (1, 3, 5, 7 e 14 dias). Era possível perceber características da fase proliferativa como a reepitelização, a presença de fibroblastos e a neovascularização, porém os grupos tratados com o óleo (T1 e T2) não apresentavam reepitelização aos três dias. Esses grupos aos 5 e 7 dias apresentavam no exame macroscópico maior intensidade de edema, hiperemia e permanência de crostas. Na microscopia, a reepitelização ainda não estava completa e a crosta era serocelular. Nos grupos C e CV, apesar de discreta, era predominante a presença de mononucleares, enquanto nos grupos T1 e T2 o infiltrado inflamatório era misto e com maior intensidade que nos outros grupos. Quatorze dias depois da incisão cirúrgica, os aspectos macroscópicos dos grupos C e CV eram semelhantes e os grupos T1 e T2, apesar de a ferida estar completamente fechada e sem crostas, a pele desses animais estava espessada e na derme do grupo T2 parecia ter fibrose mais acentuada do que nos outros grupos. Esses resultados demonstraram que o tratamento tópico com óleo de C. langsdorffii prejudicou o processo de reparação normal de ferida na presença de corpo estranho.
Mecanismos celulares e moleculares que controlam o desenvolvimento e o crescimento muscular
Authors: Silva Maeli Dal Pai , Carvalho Robson Francisco
Published: April 2009

O músculo estriado esquelético é formado pela associação de fibras musculares com a matriz extracelular. Esse tecido possui alta plasticidade e o conhecimento das características morfológicas, da miogênese, e da dinâmica do crescimento é importante para o entendimento da morfofisiologia bem como para a seleção de animais visando a melhoria na produção de carne. A maioria dos músculos estriados originam-se de células precursoras do mesoderma a partir dos somitos do embrião e o controle da diferenciação ocorre pela ação de fatores indutores ou inibidores. Um grupo de fatores transcricionais, pertencentes à família MyoD tem um papel central na diferenciação muscular. Coletivamente chamados de Fatores de Regulação Miogênica (MRFs), são conhecidos quatro tipos: MyoD, myf-5, miogenina e MRF4. Esses fatores ligam-se à seqüências de DNA conhecidas como Ebox (CANNTG) na região promotora de vários genes músculo-específicos, levando à expressão dos mesmos. As células embrionárias com potencial para diferenciação em células musculares (células precursoras miogênicas) expressam MyoD e Myf-5 e são denominadas de mioblastos. Essas células proliferam, saem do ciclo celular, expressam miogenina e MRF4, que regulam a fusão e a diferenciação da fibra muscular. Uma população de mioblastos que se diferencia mais tardiamente, as células miossatélites, são responsáveis pelo crescimento muscular no período pós natal, que pode ocorrer por hiperplasia e hipertrofia das fibras. As células satélites quiescentes não expressam os MRFs, porém, sob a ação de estímulos como fatores de crescimento ou citocinas, ocorre a ativação desse tipo celular que prolifera e expressa os MRFs de maneira similar ao que ocorre com as células precursoras miogênicas durante a miogênese. Os mecanismos de crescimento muscular são regulados pela expressão temporal dos (MRFs), que controlam a expressão dos genes relacionados com o crescimento muscular.
Métodos de estudos de sustentabilidade aplicados a aquicultura
Authors: Eler Márcia Noélia , Millani Thiago José
Published: April 2009

O objetivo deste artigo é introduzir reflexões sobre as estratégias de interconexão da aqüicultura no contexto sócio-ambiental, conclamando os atores comprometidos com o setor a pesquisar e utilizar métodos de viabilidade em conformidade com o princípio da sustentabilidade. Sendo que o conceito de desenvolvimento sustentável defendido é aquele que tem como paradigma a inclusão da dimensão social e ambiental desde o estágio de planejamento até a operação. Para tanto, a metodologia da avaliação do ciclo de vida do produto, critérios de avaliação de impacto ambiental, assim como, a adoção da bacia hidrográfica como unidade de gestão participativa, são instrumentos apresentados tendo a piscicultura de água doce como exemplo. A Legislação ambiental brasileira é apresentada como critério norteador e determinante na busca do desenvolvimento sustentável.
Aplicação dos sistemas de informação geográfica para definição de estratégias de manejo de bovinos nas pastagens
Authors: Páscoa Adriano Gomes , Costa Mateus J.R. Paranhos da
Published: April 2009

O estudo de grandes áreas de pastejo, principalmente no que diz respeito ao seu uso pelos animais, é difícil, tanto na forma de amostragem, quanto na maneira de analisar os dados obtidos. Nesse contexto o Sistema de Informação Geográfica (SIG) surge como ferramenta útil, capaz de viabilizar estudos ecológicos e comportamentais associados ao uso do espaço e dos recursos nele alocados. Dentre as ferramentas principais de um SIG com importância para o estudo de ecologia de pastagens, podemos citar a determinação de áreas de uso e trilhas, além das sobreposições, regressões e multi-regressões de mapas (compondo por exemplo: áreas de pastejo e malhadouros, características do solo, concentrações espaciais de nutrientes nas forragens, etc.). Por ser uma ferramenta de modelagem espacial computadorizada nos permite compreender e analisar de maneira mais adequada, os fenômenos de distribuição geográfica muitas vezes imperceptível nas coletas de dados convencionais. A distribuição dos animais em uma área qualquer resulta de ações combinadas de forças internas ao grupo social (por exemplo, hierarquia de dominância, liderança e formação de subgrupos) e externas a ele, como por exemplo, o posicionamento de bebedouros, sombras e cercas, que podem atuar como condicionadores de pastejo. Assim, com o entendimento do complexo arranjo do ambiente de pastagem com o uso do SIG, incluindo os fatores bióticos (tipos de vegetação, por exemplo) e abióticos (relevo), é possível desenvolver estratégias de manejo de forma a modular o comportamento dos animais, reduzindo os problemas que podem causar degradação nos recursos deste ambiente. Porém, a escolha do melhor conjunto de técnicas de análise dentro do SIG e de suas possibilidades de uso ainda está por vir, principalmente no que diz respeito às suas aplicações às condições e necessidades brasileiras.
Considerações metodológicas sobre os testes de preferência na avaliação do bem-estar em peixes
Authors: Volpato Gilson Luiz
Published: April 2009

Em uma revisão recente sobre o conceito de bem-estar em peixes, defendo que a preocupação sobre o bem-estar desses animais é definitivamente uma questão genuína, sendo nosso desafio a busca de métodos válidos para avaliação desse estado nesses animais. Nesse mesmo texto, defendo que devemos aumentar a ênfase nos estudos sobre a preferência dos animais, ao invés das tentativas frustradas de demonstrações empíricas do estado de senciência nos animais não-humanos. Partindo desse substrato teórico, no presente texto examino mais detalhadamente os testes de preferência, indicando condições e restrições importantes para que se minimize distorções que poderiam afetar interpretações sobre o estado de bem-estar dos peixes. Inicialmente, apresento condições dos peixes que devem ser consideradas para se interpretar os testes de preferência. São elas: filogenia, ritmos biológicos, condições ecológicas, ontogenia, condição social e experiência individual. Posteriormente, eu discuto condições e abordagens metodológicas para se executar e interpretar testes de preferência, numa tentativa de melhorar o entendimento sobre o que os peixes têm a nos dizer sobre seus estados internos de bem-estar.
Avanços na pesquisa com plantas forrageiras tropicais em pastagens: características morfofisiológicas e manejo do pastejo
Authors: Silva Sila Carneiro da , Nascimento Júnior Domicio do
Published: April 2009

O manejo do pastejo tem sido uma preocupação constante da pesquisa com plantas forrageiras no Brasil há muitos anos. No entanto, foi durante a última década que ocorreram grandes mudanças e um avanço significativo na compreensão de fatos e processos determinantes da correta utilização das plantas forrageiras tropicais em pastagens. O presente texto tem por objetivo traçar um breve histórico da pesquisa com plantas forrageiras e pastagens no país, apontando sua evolução, tendências, resultados e épocas de transição. Isso colocará o conhecimento disponível em perspectiva e servirá de base para a discussão da importância e relevância dos estudos envolvendo avaliações das características morfofisiológicas das plantas forrageiras para fins de planejamento e definição de estratégias de manejo do pastejo. As informações são apresentadas de maneira sistematizada, favorecendo uma visão integrada das diferentes tendências e concepções filosóficas da pesquisa com plantas forrageiras no país, apontando, de maneira crítica, a necessidade de revisão e mudança de paradigmas como forma de promover a melhoria, aperfeiçoamento e o crescimento do conhecimento acerca da produção animal em pastagens.
Estudos de expressão gênica utilizando-se microarrays: delineamento, análise, e aplicações na pesquisa zootécnica
Authors: Rosa Guilherme Jordão de Magalhães , Rocha Leonardo Bernardes da , Furlan Luiz Roberto
Published: April 2009

A tecnologia de microarrays, ou microarranjos de DNA, possibilita a avaliação simultânea da expressão de milhares de genes em diferentes tecidos em determinado organismo, em diferentes estágios de desenvolvimento ou condições ambientais. Microarrays são bastante utilizados em experimentos de genômica funcional com diversas espécies animais e vegetais, e têm sido gradativamente incorporados em diferentes áreas da pesquisa zootécnica, como crescimento e metabolismo, resposta imune a doenças, reprodução e resposta a fatores de estresse não-infecciosos (restrição alimentar, exposição a elementos tóxicos e outras condições ambientais desfavoráveis), bem como melhoramento genético animal. Tais experimentos, entretanto, são ainda consideravelmente caros, como consequência, geralmente são conduzidos com tamanhos amostrais relativamente pequenos. Por outro lado, a realização dos experimentos com microarrays, desde a coleta das amostras, até a obtenção das imagens para análise, envolve uma série de procedimentos laboratoriais de alta complexidade, que frequentemente introduzem variações adicionais aos resultados obtidos. Desta maneira, a condução de ensaios com microarrays requer cuidadoso delineamento experimental e análise estatística dos dados. Nesta apresentação são discutidos princípios básicos do planejamento de ensaios com microarrays, bem como as ferramentas estatísticas e computacionais mais comuns para a análise dos mesmos. São também discutidos alguns exemplos de aplicação de experimentos com microarrays em zootecnia e, numa última seção, são traçadas algumas considerações finais envolvendo os tópicos gerais abordados.
Avanços metodológicos na seleção do sexo de espermatozóides bovinos para utilização no melhoramento genético e na produção animal
Authors: Lima Vera Fernanda Martins Hossepian de
Published: April 2009

O mercado demanda, desde final da década de 20, uma tecnologia para a sexagem de espermatozóides que possa ser inserida na indústria de produção de sêmen congelado e que tenha as seguintes características: a) não altere a viabilidade espermática; b) seja compatível com a congelação do espermatozóide sexado; c) permita a sexagem de espermatozóides previamente congelados e descongelados; d) permita a produção de várias doses de sêmen sexado congelado por dia, com custo compatível ao mercado. A importância dessa tecnologia para maximizar a produção animal a um custo baixo tem sido um desafio da pesquisa a vários anos. A possibilidade de produzir, em escala comercial, doses de sêmen enriquecidas com espermatozóides X ou Y aumentará os benefícios do uso da inseminação artificial no seu papel de maximizar o progresso genético entre gerações de acordo com os requerimentos de cada programa de melhoramento animal. Diferentes rotas tecnológicas são percorridas na tentativa de selecionar-se o sexo em mamíferos, tanto nas espécies de interesse zootécnico quanto em espécies ameaçadas de extinção, animais de companhia. Neste sentido, existem duas alternativas: a separação de espermatozóides portadores do cromossomo X, daqueles portadores do cromossomo Y; ou a sexagem de embriões pré-implantados. A viabilidade da sexagem de espermatozóides em bovinos é esperada por muitos anos e os desenvolvimentos recentes tornaram essa tecnologia de aplicação commercial. Entretanto, muitas limitações ainda existem, principalmente, referente à taxa de gestação em condições de campo. Isso restringe a utilização dessa tecnologia no melhoramento genético e produção animal. Nessa palestra abordaremos os potenciais sistemas de criação e produção que poderão beneficiar-se com a sexagem de espermatozóides, quando essas limitações forem solucionadas.