Experimental transmission of a dermal sarcoma in fingerling walleyes (Stizostedion vitreum vitreum)

Dermal sarcoma is a benign skin tumor of adult walleyes (Stizostedion vitreum vitreum) with a suspected viral etiology. A laboratory study was initiated to determine if the tumor could be experimentally transmitted by inoculating young walleyes with materials prepared from tumors from adult fish. Eighty walleye fingerlings were divided into four groups of 20 fish each. Two groups were inoculated intramuscularly at 4 months of age either with live tumor cells or with cell-free filtrates of sonicated tumor cells. The two other groups were used as controls and were inoculated either with cultured cells from normal walleye fry or with tissue culture media. Neoplasms, similar to the dermal sarcoma affecting adult walleyes, were observed after 4 months only in fingerlings inoculated with cell-free filtrates of sonicated tumor cells. Like the tumor affecting wild adult walleyes, the transmitted tumors were restricted to the dermis and originated from the superficial surface of scales. They never invaded locally and never metastasized. The transmitted tumors differed from tumors of adult walleyes in their severity and the absence of osteoid. The multicentric origin of transmitted walleye dermal sarcoma suggests that the virus spreads systemically and that tumor cells are polyclonal. This successful transmission of the lesion, along with the presence of C-type virus particles budding from tumor cells in two of seven tumor-bearing fingerlings, supports a retroviral etiology.     

Fluxes of Ca(2+), K(+) and Cl(-) across the surfaces of detached needles from Sitka spruce trees: pathways and compartmentation

Uptake and efflux of (36)Cl(-), (45)Ca(2+) and (42)K(+) were measured in water-infiltrated detached needles from Sitka spruce (Picea sitchensis (Bong.) Carr.) trees incubated in 1 mol m(-3) KCl or CaCl(2) or 2 mol m(-3) NaCl solutions or in artificial rain water containing mmol m(-3) amounts of these ions. Surface efflux was measured separately from leakage from the cut ends of the needles. Needles loaded with (36)Cl(-) and killed in liquid N(2) before elution displayed a rapid and extensive loss of radioisotope, indicating that mesophyll cell membranes were the limiting factor for (36)Cl(-) exchange. Data for live needles revealed a novel phase of (36)Cl(-) efflux, with an exchange halftime of about 20 min, which was faster than that for either the vacuole or the cytoplasm, but much slower than that for the free space. The novel phase was interpreted as representing diffusion of Cl(-) through the predominantly negatively charged cuticle. Killing needles loaded with (45)Ca(2+) or (42)K(+) also increased efflux relative to that from live needles, but only to a limited degree, indicating that the main factor limiting cation efflux was the cuticle. During the first hours of (45)Ca(2+) uptake, the isotherms displayed a shoulder, indicating that there was a significant Donnan free space phase in the cuticle for Ca(2+). A shoulder was absent from (42)K(+) uptake isotherms because of the preferential adsorption of divalent cations on the exchange sites.     

The behaviour of particle board and hardboard beams during moisture cycling

Summary The effects of creep at constant conditions of moisture content and the effects of deformations occurring during cycling of moisture content have been studied in loaded beams of particleboard and hardboard. The variations in stiffness in loaded and unloaded beams of particleboard during moisture cycling were also determined. Contrary to the findings of some workers but in agreement with the findings of another, the increases in the deflections of loaded beams of particleboard during cycling of moisture content were due mainly to desorption of moisture. Qualitatively similar behaviour was found for particleboard, hardboard and wood but quantitatively the effects were greatest in particleboard and hardboard. It appears that the basic mechanism of the transient effects in bending, arising with the simultaneous action of load and change in moisture content, may be similar in wood, particleboard and hardboard.     

Application of real options theory to forestry investment analysis

This paper demonstrates the utility of the real options approach to forestry investment analysis. The main objectives are to discuss the real option theory and show how it can be adopted to model uncertainty and managerial flexibility in forest management and investment. Secondly, we show how to calculate the option values of selected options that may be available to managers of forest industry firms. The paper provides an empirical application, which compares a forestry investment using the static Faustmann model and the real options approach. Four management options are used for the real options approach: an option to delay reforestation, an option to expand the size of the wood processing plant, an option to abandon the processing plant if timber prices fall below a certain level or due to corporate take-over, and multiple options that evaluated all three options together. All options were evaluated using the binomial option-pricing model, where timber values are assumed to follow a multiplicative binomial process. The results show that the Faustmann analysis rejected the investments as unprofitable, while the option analysis showed that all three options were highly valuable if exercised. When real options are considered, the traditional Faustmann model for assessing the profitability of a forestry investment may fail to provide an adequate decision-making framework because it does not properly value management's ability to adjust to shocks in the economy, as well as risks and uncertainty.     

Movements of Atlantic salmon migrating upstream through a fish-pass complex in Scotland

Abstract  – Movements of adult Atlantic salmon were tracked through a series of four fish passes and an impoundment on the River Conon system, Northern Scotland. Proportions of fish passing individual obstructions ranged from 63 to 100%. The cumulative effect was that only 4 of the 54 tagged fish reached the spawning areas. The fish were delayed for 1–41 days at a pool-and-overfall ladder and 1–52 days at a Borland fish lift. The fish swam through a 10 km long reservoir at 0.21–1.16 km·h⁻¹. A total of 13 fish negotiated a 2.5 km long, 3 m diameter diversion tunnel through a mountain to their home river. High levels of electromyogram (EMG) activity were recorded during ascent of a pool-and-overfall fish ladder, indicating that high energy demanding burst swimming was required.     

An investigation of avoidance by Antarctic krill of RRS James Clark Ross using the Autosub-2 autonomous underwater vehicle

The autonomous underwater vehicle (AUV) Autosub-2 was deployed on eight missions ahead of RRS James Clark Ross in the northern Weddell Sea and in the Bransfield Strait, Southern Ocean, to assess avoidance of the research vessel by Antarctic krill Euphausia superba. The AUV was equipped with the same type of scientific echosounder as the research vessel (Simrad EK500 operating at 38 and 120 kHz) and measured the density of krill along transect acoustically (g m⁻² wet mass) prior to the ship’s arrival. We hypothesised that if krill avoided the ship, perhaps in response to radiated noise, then the ship should detect less krill than the AUV which is known to have much lower noise levels than the ship. We were unable to detect any significant difference between the density of krill detected by the ship or the AUV, either at the transect level or at finer scales within transects. We conclude, therefore, that avoidance by krill of RRS James Clark Ross will not significantly bias acoustic estimates of krill abundance by this vessel.     

Enteral nutrition by tube

When oral intake is unsatisfactory or contraindicated, maintenance of nutrition by tube feeding is an alternative to the parenteral route. A large volume of research data supports the decision to use the enteral route whenever possible. Entry of food into the alimentary tract is a stimulus to structural and functional maintenance of that tract. Enteral nutrition can be given via indwelling nasoesophageal, pharyngostomy, esophagostomy, percutaneous or surgical gastrostomy, or enterostomy tube. Use of an appropriate catheter, familiarity with the technique used, and careful patient selection and monitoring are important factors in successful tube feeding. Blenderized pet food diets should be fed whenever possible; commercially available liquid diets provide an alternative when tube caliber or patient factors preclude the use of blenderized foods.     

Effect of active immunization against growth hormone-releasing factor on growth and onset of puberty in beef heifers.

Angus and Charolais heifers (195 +/- 7 kg) were actively immunized against growth hormone-releasing factor (GRF) to evaluate the effect on concentrations of somatotropin (ST), insulin-like growth factor I (IGF-I), insulin (INS), growth, and onset of puberty. Primary immunizations were given at 184 +/- 7 d of age (d 0 of experiment) by injecting (s.c.) 1.5 mg of GRF-(1-29)-Gly-Gly-Cys-NH2 conjugated to 1.5 mg of human serum albumin (GRFi, n = 22) or 1.5 mg of human serum albumin (HSAi, n = 21). Booster immunizations of .5 mg of antigen were given on d 62, 92, 153, and 251. Antibody binding (percentage at 1:2,000 dilution) to [125I]GRF on d 69 was greater (P less than .01) in GRFi (53.7 +/- 4.5) than in HSAi (10.1 +/- .6) heifers. Serum concentration (ng/ml) and frequency (peaks/5 h) of ST release, respectively, on d 78 were lower (P less than .01) in GRFi than in HSAi heifers (3.3 +/- .1 vs 5.6 +/- .2 and .9 +/- .3 vs 2.3 +/- .2). Serum IGF-I (ng/ml) was lower (P less than .01) in GRFi than in HSAi heifers on d 69 (41 +/- 5 vs 112 +/- 4). Serum INS (microU/ml) on d 78 was lower (P less than .05) in GRFi (2.2 +/- .1) than in HSAi (3.8 +/- .2) heifers. Feed intake, ADG, and feed efficiency were lower (P less than .05) in GRFi than in HSAi heifers. Hip height was lower (P less than .01) and fat thickness was greater (P less than .05) in GRFi than in HSAi heifers by d 132 and 167, respectively. Percentage of heifers attaining puberty (progesterone greater than 1 ng/ml for two consecutive weeks) by d 209 and 379 (12.9 and 18.5 mo of age), respectively, was lower (P less than .05) in GRFi (40.9 and 45.5) than in HSAi (81.0 and 100). In conclusion, growing heifers were successively immunized against GRF. Active immunization against GRF resulted in decreased serum concentration of ST, IGF-I, and INS. In addition, GRF immunization led to lowered feed intake, ADG, and feed efficiency, increased fat depth, and delayed onset of puberty in heifers. We propose that ST and IGF-I are important metabolic mediators involved in the initiation of puberty in heifers.     

Influence of type of enclosure on exercise fitness of dogs

The effect of various confinement conditions on physical fitness in dogs was evaluated. Eighteen 9.5- to 10-month-old female purpose-bred Beagles were maintained individually for 3 months at a time in 1 of 6 confinement conditions: Condition A--an outdoor housing area with a conventional dog house and free access to a 6.1 x 9.1-m pen; condition B--outdoor kennel with a conventional dog house and free access to a 1.8 x 6.1-m run; condition C--indoor environmentally controlled 1.2 x 3.66-m run; condition D-0.9 x 1.2 x 0.84-m conventional laboratory cage in an indoor environmentally controlled room; condition E--0.9 x 1.2 x 0.84-m conventional laboratory cage in an indoor environmentally controlled room with treadmill exercise (7 km/h at a 10% grade) for 30 min/d, 5 d/wk; condition F--0.71 x 0.86 x 0.69-m conventional laboratory cage in an indoor environmentally controlled room. During the final week of each 3-month interval, muscle succinate dehydrogenase enzyme activities and submaximal exercise heart rates (during treadmill exercise) were determined to estimate physical fitness. Also, 5 days after being moved into a different housing condition, blood samples were collected for plasma cortisol determination. The type of confinement condition for dogs had little effect on muscle succinate dehydrogenase activity, but had a modest effect on submaximal exercise heart rates of dogs.(ABSTRACT TRUNCATED AT 250 WORDS)