Evaluation of Live Feeds for Larval and Postlarval Mahimahi Coryphaena hippurus

Live hatchery feeds were assayed for fatty acids (FA), amino acids (AA), and their ability to support growth and survival of larval and postlarval mahimahi Coryphaena hippurus at two different hatchery stages. Euterpina acuritrons copepods (C), mahimahi yolk-sac larvae (YSL), Artemia parthenogenica brine shrimp nauplii (BSn), A. parthenogenica juveniles (BSj), and Brachionus plicatilis rotifers (R) were assayed, using several enrichment media. There was little difference in AAs among feeds.
Levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were about 10 times higher in YSL than in their feeds. This explains previous findings where first stage larval survival (0–9 days) was not affected by feed HUFA levels. Second stage survival was significantly higher when larvae were fed copepods. Enrichment with 100 ppm SuperSelco greatly improved the survival of larvae that were fed brine shrimp. The even higher omega-3 fatty acids found in copepods appear to be important for survival of larvae under more stressful conditions.
Brine shrimp juveniles enriched with SuperSelco are a good food for postlarval mahimahi. Yolksac larvae of mahimahi are an even better food, promoting faster growth at less cost, for large scale mahimahi aquaculturists. Different batches of yolksac mahimahi larvae varied by a factor of 10 in their concentration of DHA, but always had the highest level of DHA as much as 40% of total fatty acids (FAs). These "high HUFA" batches of YSL also had the highest levels of EPA and total fatty acids. The data suggest that climate and broodstock age may have considerable influence on larval nutrition.     

A test of the individual feeding activity and food size preference in rainbow trout using demand feeders

Feeding activity and food size preferences were investigated in three groups of rainbow trout with initial weights ranging from 200 to 1000 g. Fish were given the option of releasing food from either of two demand feeding devices that contained either 6 mm or 9 mm food pellets. Individual biting activity (to activate release of food) was continuously monitored using specially designed passive integrated transponders (PIT-tags). In each of the groups, biting activity was strongly influenced by three individuals, which accounted for 70–85% of the total. Thus, high bite activity by few individuals indicates the development of social dominance hierarchies. There was no statistically significant correlation between number of bites and growth rate, indicating that the fish that operated the demand feeders did not gain any growth advantage. Trout that dominated the actuation of the feeders were found among both medium- and large-sized fish. There was no evidence of active food size selection, and the fish that most frequently operated the feeders defended one area of the tank rather than preferring the trigger that would have delivered food of the optimal size.     

Use of artificial landscapes to isolate controls on burn probability

Techniques for modeling burn probability (BP) combine the stochastic components of fire regimes (ignitions and weather) with sophisticated fire growth algorithms to produce high-resolution spatial estimates of the relative likelihood of burning. Despite the numerous investigations of fire patterns from either observed or simulated sources, the specific influence of environmental factors on BP patterns is not well understood. This study examined the relative effects of ignitions, fuels, and weather on mean BP and spatial patterns in BP (i.e., BP variability) using highly simplified artificial landscapes and wildfire simulation methods. Our results showed that a limited set of inputs yielded a wide range of responses in the mean and spatial patterning of BP. The input factors contributed unequally to mean BP and to BP variability: so-called top-down controls (weather) primarily influenced mean BP, whereas bottom-up influences (ignitions and fuels) were mainly responsible for the spatial patterns of BP. However, confounding effects and interactions among factors suggest that fully separating top-down and bottom-up controls may be impossible. Furthermore, interactions among input variables produced unanticipated but explainable BP patterns, hinting at complex topological dependencies among the main determinants of fire spread and the resulting BP. The results will improve our understanding of the spatial ecology of fire regimes and help in the interpretation of patterns of fire likelihood on real landscapes as part of future wildfire risk assessments.     

Effect of chronic administration of a gonadotropin‐releasing agonist on luteal function and pregnancy rates in dairy cattle

Increased embryonic losses may be associated with inadequate progesterone (P4) concentrations in high‐producing lactating dairy cattle. The objectives of the present studies were to determine if chronic administration of a gonadotropin‐releasing hormone (GnRH) agonist, Deslorelin, would increase circulating P4 concentrations and subsequently increase pregnancy rates in dairy cattle. Administration of Deslorelin for 12 days increased (p < .05) luteal volume and circulating P4 concentrations in primiparous lactating dairy cows, but increased only luteal volumes in multiparous cows. Treatment with Deslorelin increased Day 45 pregnancy rates in cows as compared to untreated controls. Chronic treatment with Deslorelin in dairy cattle; (a) increased luteal volume of the primary CL, (b) induced accessory CL, (c) increased circulating P4 concentration in primiparous cows only, (d) did not lengthen the estrous cycle upon removal of treatment, and (e) increased pregnancy rates. Although luteal volume was increased in multiparous cows and circulating P4 concentrations were not with Deslorelin treatment, there was an apparent effect on pregnancy rates. This hormonal strategy may represent a suitable model to address local effects of P4 and GnRH/luteinizing hormone on uterine environment and subsequent embryonic survival.     

Closed fluoroscopic-assisted spinal arch external skeletal fixation for the stabilization of vertebral column injuries in five dogs

Objective— To evaluate outcome after closed fluoroscopic-assisted application of spinal arch external skeletal fixators in dogs with vertebral column injuries.
Study Design— Retrospective case series.
Animals— Dogs with traumatic vertebral column injuries (n=5).
Methods— Medical records of dogs with vertebral column fractures and/or luxations stabilized with spinal arch external skeletal fixator frames applied using a closed fluoroscopic-assisted technique were reviewed. Owners were contacted to obtain long-term clinical outcomes.
Results— Five dogs (age range, 6–72 months; weight, 10–54 kg) had traumatic vertebral column injuries stabilized with spinal arch external skeletal fixators applied in closed fashion. Injuries involved vertebral segments of the thoracolumbar junction, lumbar spine, and lumbosacral junction. Immediately postoperatively, 4 dogs had anatomic alignment of their vertebral fracture/luxation; 1 dog had 1 mm of vertebral canal height compromise. Time to fixator removal ranged from 65 to 282 days (141±87 days). All dogs had regained satisfactory neurologic function by 3 months. At long-term follow-up (range, 282–780 days; mean 445±190 days) all dogs were judged to have good to excellent return of function by their owners.
Conclusion— Successful closed fluoroscopic-assisted application of external skeletal fixators using spinal arches provided satisfactory reduction with few complications in 5 dogs. Return to function was judged to be good to excellent in all dogs at long-term evaluation.
Clinical Relevance— Closed fluoroscopic-assisted application of ESF using spinal arches provided satisfactory reduction and effective stabilization of spinal fractures with few complications and should be considered as a treatment approach.     

Comparison of thermal dilution and electrical impedance dilution methods for measurement of cardiac output in standing and exercising horses

OBJECTIVE: To compare cardiac output measured in the pulmonary artery and a carotid artery by use of thermal and electrical impedance dilution. Animals-7 fit, clinically normal Standardbreds between 2 and 5 years of age. PROCEDURE: Transient changes in electrical impedance and temperature of blood were induced by bolus injections of ice-cold saline hypertonic (6% and 9% NaCl) solutions. Cardiac output was calculated by applying Stewart-Hamilton principles to the indicator dilution transients. Measurements were made during sequential exercise episodes on a level treadmill over approximately an 8-fold range of cardiac output values. RESULTS: We detected agreement between cardiac output determined by use of electrical impedance dilution at the pulmonary artery and carotid artery. Cardiac output from thermal dilution measured at the carotid artery exceeded that measured at the pulmonary artery. Cardiac output from the thermal dilution technique exceeded cardiac output from the electrical impedance dilution technique at both locations. CONCLUSIONS AND CLINICAL RELEVANCE: The electrical impedance indicator is conserved on first transit; therefore cardiac output measured by electrical impedance dilution at the carotid artery is reliable over a large range of values. Thermal dilution provides a larger estimate of cardiac output, compared with the electrical impedance dilution technique, probably because of a loss of indicator. The transpulmonary electrical impedance dilution technique may have potential for clinical application, particularly in animals in which catheterization of the pulmonary artery is not appropriate or blood loss must be minimized.     

Proteoglycan-specific molecular switch for RPTPσ clustering and neuronal extension

Heparan and chondroitin sulfate proteoglycans (HSPGs and CSPGs, respectively) regulate numerous cell surface signaling events, with typically opposite effects on cell function. CSPGs inhibit nerve regeneration through receptor protein tyrosine phosphatase sigma (RPTPσ). Here we report that RPTPσ acts bimodally in sensory neuron extension, mediating CSPG inhibition and HSPG growth promotion. Crystallographic analyses of a shared HSPG-CSPG binding site reveal a conformational plasticity that can accommodate diverse glycosaminoglycans with comparable affinities. Heparan sulfate and analogs induced RPTPσ ectodomain oligomerization in solution, which was inhibited by chondroitin sulfate. RPTPσ and HSPGs colocalize in puncta on sensory neurons in culture, whereas CSPGs occupy the extracellular matrix. These results lead to a model where proteoglycans can exert opposing effects on neuronal extension by competing to control the oligomerization of a common receptor.     

Crystal structure of the malaria vaccine candidate apical membrane antigen 1

Apical membrane antigen 1 from Plasmodium is a leading malaria vaccine candidate. The protein is essential for host-cell invasion, but its molecular function is unknown. The crystal structure of the three domains comprising the ectoplasmic region of the antigen from P. vivax, solved at 1.8 angstrom resolution, shows that domains I and II belong to the PAN motif, which defines a superfamily of protein folds implicated in receptor binding. We also mapped the epitope of an invasion-inhibitory monoclonal antibody specific for the P. falciparum ortholog and modeled this to the structure. The location of the epitope and current knowledge on structure-function correlations for PAN domains together suggest a receptor-binding role during invasion in which domain II plays a critical part. These results are likely to aid vaccine and drug design.