Physiology during smoltification in Atlantic salmon: effect of melatonin implants     

S. O. Handeland  A. K. Imsland  B. Th. Björnsson  S. O. Stefansson  M. Porter 《Fish physiology and biochemistry》2013,39(5):1079-1088

Melatonin implants were used to override natural melatonin rhythm in groups of juvenile Atlantic salmon, Salmo salar, raised at simulated natural photoperiod (SNP) and constant light (LL) from mid-March until end of August. The experiment contained also both sham control (with non-melatonin implants) and control (no implants). No differences were found in the experimental variables between these two control groups. Growth and food intake were negatively affected by melatonin implantation. Overall, higher GH levels were observed in the SNP melatonin-implanted group, whereas no differences in GH levels were seen between the SNP control, LL control, or the LL melatonin-implanted groups. Highest food intake was seen in the LL control group. No differences in food intake were recorded between the LL melatonin-implanted and SNP control groups. Gill Na⁺, K⁺, ATPase (NKA) activity was influenced by time as well as the interaction between photoperiod and time. No differences in gill NKA activity or plasma chloride levels following transfer to seawater were seen between the groups with melatonin implants and their controls. Based on the present results, it seems apparent that melatonin does play a role in regulating food intake and growth in Atlantic salmon smolts.  相似文献   

RISK ASSESSMENT IN OPEN-OCEAN AQUACULTURE: A FIRM-LEVEL INVESTMENT-PRODUCTION MODEL     

Di Jin  Hauke Kite-Powell  Porter Hoagland 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):369-387

ABSTRACT

We develop a framework for risk assessment in open-ocean aquaculture. The framework consists of three components: a firm-level investment-production model simulates a specific grow-out project and estimates the project's benefit-cost values, a second model calculates the risk premium for a risk-averse investor, and a third model quantifies the option value for a risk-neutral investor. We show that under uncertainty, the traditional NPV rule for making an investment should be modified. We illustrate our models using a case study of open-ocean aquaculture of Atlantic cod (Gadus morhua) in New England.  相似文献   

Staggers in horses grazing paspalum infected with Claviceps paspali     

AJ Cawdell-Smith  CJ Scrivener  WL Bryden 《Australian veterinary journal》2010,88(10):393-395

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Critical Loads of Acidity to Protect and Restore Acid-Sensitive Streams in Virginia and West Virginia     

Timothy J. Sullivan  Bernard J. Cosby  Todd C. McDonnell  Ellen M. Porter  Tamara Blett  Richard Haeuber  Cindy M. Huber  Jason Lynch 《Water, air, and soil pollution》2012,223(9):5759-5771

The purpose of the research described here is to apply a new approach for generating aquatic critical load (CL) and exceedance calculations for an important acid-sensitive region of the eastern USA. A widespread problem in regional aquatic acidification CL modeling for US ecosystems has been the lack of site-specific weathering data needed to derive accurate model CL estimates. A modified version of the steady-state water chemistry CL model was applied here to estimate CL and exceedances for streams throughout acid-sensitive portions of Virginia and West Virginia. A novel approach for estimating weathering across the regional landscape was applied, based on weathering estimates extracted from a well-tested, process-based watershed model of drainage water acid?Cbase chemistry and features of the landscape that are available as regional spatial data coverages. This process allowed extrapolation of site-specific weathering data from 92 stream watersheds to the regional context in three ecoregions for supporting CL calculations. Calculated CL values were frequently low, especially in the Blue Ridge ecoregion where one-third of the stream length had CL?<?50?meq/m²/year to maintain stream ANC at 50???eq/L under steady-state conditions. About half or more of the stream length in the study region was in exceedance of the CL for long-term aquatic resource protection under assumed nitrogen saturation at steady state. Land managers and air quality policy makers will need this information to better understand responses to air pollution emissions reductions and to develop ecoregion-specific air pollution targets.  相似文献   

Report of The Site Selection Committee to the PAA Business Meeting Wednesday July 27, 1994     

Brian L. Rex  Joe Sieczka  Alexander Pavlista  Duane Preston  Pete Weingartner  Robert O’Keefe  Jonathon Whitworth  Chesley E. Smith  Rob Davidson  Gregory Porter  Dan Hane  Terry Work 《American Journal of Potato Research》1994,71(11):782-794

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Mainestay: A high-yielding, round white potato variety for fresh market     

A. F. Reeves  G. A. Porter  T. M. Work  D. H. Lambert  A. A. Davis  E. S. Plissey 《American Journal of Potato Research》1997,74(4):255-263

The Mainestay potato variety is high-yielding and late-maturing producing attractive, round, white-skinned, white-fleshed tubers with medium-shallow eyes. Its major use is expected to be as a maincrop tablestock variety. Mainestay appearance ratings are similar to those of Katahdin, and greening in Mainestay tubers is less than in Kennebec. Most boil and bake qualities were rated equal to Katahdin in at least half of the tests, and Mainestay usually has a low incidence of internal defects. However, purple streak, heat necrosis, vascular discoloration, and heat sprouts have been seen on occasion. Mainestay tubers do not show the net necrosis caused by potato leafroll virus, and have shown very little hollow heart or blackspot bruising. Mainestay is susceptible to common scab and acid scab, but moderately resistant to verticillium wilt (Verticillium, albo-atrum andV. dahliae), early blight (Alternaria solani), rhizoctonia (Rhizoctonia solani), dry rot (Fusarium sambucinum), and pink rot (Phytophthora erythroseptica). It is moderately susceptible to the common race of late blight (Phytophthora infestans). Mainestay tubers are slow to mature after vine kill, and additional time is required prior to harvest in order to allow for proper periderm development and to reduce storage losses.  相似文献   

St. Johns: A round white potato variety for fresh market     

A. F. Reeves  G. A. Porter  F. E. Manzer  T. M. Work  A. A. Davis  D. R. Hensel  J. R. Shumaker 《American Journal of Potato Research》1996,73(2):89-98

The St. Johns potato variety is high-yielding and late-maturing with attractive, round to oblong, white-skinned, white-fleshed tubers with mediumshallow eyes. Its major use is expected to be as a maincrop tablestock variety. Taste panels rated St. Johns better than or equal to Katahdin in texture, color, mealiness, and flavor. St. Johns tubers do not show the net necrosis caused by potato leafroll virus, and are resistant to golden nematode, corky ringspot, hollow heart, and blackspot bruising. St. Johns is also moderately resistant to greening, shatter bruise, verticillium wilt, early blight, common scab, the common race of late blight, leafroll,Fusarium sambucinum (dry rot) andErwinia carotovora (soft rot), although some breakdown has been reported in commercial storages. Symptoms of leafroll virus infection are somewhat difficult to detect.  相似文献   

Pathology in practice. Liposarcoma     

Cramer SD  Porter KL  Rochat MC  Lamm CG 《Journal of the American Veterinary Medical Association》2011,239(6):757-759

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Intramyocardial haematoma causing right ventricular outflow obstruction after brown snake (Pseudonaja species) envenomation in a dog     

K Kang  CR Sharp  CJ Boyd  K Turner 《Australian veterinary journal》2020,98(9):455-461

A 15-month-old, male neutered Staffordshire Bull Terrier cross was presented to its referring veterinarian collapsed and agonal. He was immediately intubated, manually ventilated, and treatment commenced for presumptive snake envenomation with two vials of Tiger/Multi-Brown Snake Antivenom (minimum 7000 units/vial). The dog was transferred to a referral hospital intubated. Additional diagnostics performed following arrival at the referral hospital included a urine snake venom detection kit test, which was positive for brown snake immunotype. Three additional vials of Tiger/Multi-Brown Snake Antivenom (minimum 7000 units/vial) were administered until the dog was extubated and able to stand. Venom-induced consumptive coagulopathy (VICC) was diagnosed based on prolonged clotting times and scleral haemorrhage. Paroxysms of right ventricular outflow tract (RVOT) origin ventricular arrhythmias were treated with lignocaine and sotalol. Four days after presentation, a new-grade IV/VI systolic heart murmur was auscultated, prompting an echocardiogram. An anechoic and compartmentalised mass measuring 43 mm × 19 mm was visualized within the right ventricular wall at the RVOT, immediately adjacent to the pulmonic valve. The mass was causing a RVOT obstruction. Its appearance was suggestive of an intramyocardial haematoma, most likely secondary to VICC. The dog remained cardiovascularly stable, and treatment consisted of supportive care. Recheck echocardiograms at 2 and 7 weeks after discharge revealed progressive improvement of the intramyocardial mass and resolution of the associated heart murmur. Although intramyocardial haematomas are rare, it should be considered as a differential in dogs that develop a newly diagnosed heart murmur and/or cardiac arrhythmia following brown snake envenomation.  相似文献   

Net revenues of potatoes rotated with other crops     

John V. Westra  Kevin J. Boyle  Gregory A. Porter 《American Journal of Potato Research》1995,72(2):99-117

Using actual potato production data from Aroostook County, Maine, we investigate the possibility of producers increasing net revenues by modifying rotation practices. By examining rotations as a whole, and incorporating yield effects and changes in production costs across rotations, more realistic pictures of net revenues for each rotation develop than if net revenue for each crop within a rotation is considered independently. Our analyses indicate producers can alter their production practices within the range of rotations used locally to increase net revenues. A key finding confirms the synergistic interaction between grains underseeded with a green manure crop and round-white potato varieties, resulting in decreased production costs, greater potato yields, and increased net revenues.  相似文献