Optimization of triploidy induction in the blacklip abalone, Haliotis rubra (Leach, 1814), using 6-dimethylaminopurine

Optimal conditions of 6‐dimethylaminopurine (6‐DMAP) for triploidy induction in the blacklip abalone Haliotis rubra (Leach, 1814) were investigated, targeting inhibition of second polar body (PB2) formation. Two experiments were conducted at a water temperature of 17.5–18.5°C where factorial combination of (1) four dosages (DSs) of 100, 150, 200 and 250 μM 6‐DMAP, four starting times (STs) of 15, 20, 25 and 30 min post fertilization, and two treatment durations (TDs) of 20 and 30 min and (2) three DSs of 50, 100 and 150 μM 6‐DMAP, three STs of 15, 20 and 25 min post fertilization, and three TDs of 10, 20 and 30 min, were applied respectively. Day 3 larvae were sampled for triploidy and survival. Percent triploidy was verified using flow cytometry (FCM). Results show that optimal inductions that combine both high rates of triploidy and reasonable survival were those treatments commenced 15 or 20 min post fertilization and continued for 20 or 30 min, using 100 μM 6‐DMAP. These conditions induced rates of triploidy and relative survival of 80.5–93.3% and 36.5–40.2%, respectively, in the first experiment, and corresponding rates were 79.1–93.6% and 20.7–43.0% in the second experiment. High percent triploidy were also obtained in a number of treatments using 150 μM 6‐DMAP, but with overall survival rates generally lower than those using 100 μM 6‐DMAP.     

Growth and mortality of sibling triploid and diploid Sydney rock oysters, Saccostrea glomerata (Gould), in the Camden Haven River

Growth and mortality of sibling triploid and diploid Sydney rock oysters, grown at two tidal heights, three stocking densities and three different sites on the Camden Haven River estuary, were compared. Triploids grew faster than diploids. The majority of the growth rate difference occurred after the oysters reached 2 years of age. By 3.2 years, triploids were 49% heavier than diploids. Oysters grown intertidally were larger than those grown subtidally. Oysters stocked at the lightest density of 2 L per basket grew to a significantly larger size than baskets stocked at 3 or 4 L. Growth rates were significantly different at the three sites. Growth was reduced the further the oysters were from the mouth of the estuary. There was no significant difference in mortality between ploidy level, but there were differences between tidal heights, stocking densities and sites. Intertidal oysters suffered higher mortality than subtidal. Oysters stocked at the highest density had a significantly higher mortality than the lowest density; neither of these was significantly different from the medium density. The site closest to the mouth of the estuary had significantly lower mortality than the middle and upper estuary sites.     

The utilization of clam waste meal as a protein source for rainbow trout Salmo gairdneri

Solid waste recovered from clam processing wash water was evaluated for its utilization as a replacement protein for fish meal. Three diets, diets 1 and 2 formulated to simulate the Oregon Moist Pellet (OMP) and diet 3 (Rangen), were fed to rainbow trout (Salmo gairdneri) for eight weeks. The effects of the clam waste meal on fish growth, food conversion, carcass composition and whole body fatty acid content were determined. The clam waste diet supported maximum growth and food conversion. Carcass analysis of moisture, protein and lipid contents were similar among the moist feeds. The dietary levels of 20:5w3 + 22:6w3 and total polyunsaturated fatty acids (PUFAs) were significantly higher in the clam waste diet pellet.     

Rapid differentiation of Artemia spp. Populations by thin layer isoelectric focusing

Artemia spp. of various geographic origins, yearly collection lots, developmental stages, and a binary geographic mixture were analyzed by thin layer polyacrylamide gel isoelectric focusing (IEF). IEF of geographical Artemia samples yielded unique profiles for each population in the pH range employed. Parthenogenetic populations of Artemia exhibited IEF patterns which were, generally, dominated by fewer proteins; bisexual populations exhibited more evenly distributed, complex protein patterns. There were similarities reflected in IEF profiles of geographically isolated Artemia descended from a common ancestry. Yearly collections of Artemia exhibited no apparent differences in IEF protein patterns. There were differences noted in three developmental stages of Artemia. A binary mixture of geographic populations yielded IEF patterns intermediate to those of the component pure samples.     

Nitrous oxide emission from soils at low moisture contents

The production of nitrous oxide by soils was studied over short periods at a range of moisture contents up to field capacity with a highly-sensitive gas Chromatographic method.Nitrous oxide (N₂O) was emitted from all soils studied at all soil moisture contents, which ranged from air dry to field capacity. The rate of emission increased with increasing moisture content and with increasing temperature up to 37°C.The evolution of N₂O was not due to displacement of soil air during wetting. It was inhibited by HgCl₂ and toluene, and was prevented by formaldehyde and autoclaving. Thus it appeared to be due to microbiological processes.The results of experiments with nitrification and denitrification inhibitors suggest that a considerable part of the N₂O was produced by the oxidation of ammonia. Production by denitrification of nitrate cannot be ruled out. The relative importance of these two mechanisms probably depends on the moisture and oxygen content of the soil.It is concluded that the microbial production of N₂O is continuous in soil at all moisture contents. The process at low moisture contents constitutes an important component in the cycle which maintains the N₂O concentration in the atmosphere.     

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.     

A closed ammonia cycle within a plant canopy

Ammonia losses to the atmosphere from a grass-clover pasture were measured by a combined chemical-micrometeorological technique. Losses from the pasture when grazed were quite considerable (~13g N ha^?1 h^?1) but when ungrazed they were comparatively small (2 g N ha^?1 h^?1).Measurements within the canopy of the ungrazed pasture at maturity indicated a large production of NH₃ near the ground surface and almost complete absorption of it by the plant cover. The amounts of NH₃ absorbed appeared to be too large for stomatal uptake alone.This closed NH₃ cycle has important consequences for the field assessment of N₂ fixation and gaseous N losses.     

Successful treatment of suspected essential thrombo-cythaemia in the dog

Essential thrombocythaemia in an eight-year-old Irish setter is described. The condition is characterised by an autonomous overproduction of thrombocytes in the absence of overt leukaemia. This is believed to be the first recorded case of this condition in the dog. The paper describes the diagnosis and treatment by combination chemotherapy using vincristine, cytosine arabinoside, cyclophosphamide and prednisolone.     

Serum amylase and isoamylase values in dogs with pancreatic disease

Serum amylase and isoamylase values were determined in three groups of dogs. The first group contained control dogs while the other groups contained dogs with confirmed exocrine pancreatic insufficiency and diabetes mellitus respectively. The trypsin-like immunoreactivity test was also carried out on sera from dogs with exocrine pancreatic disease (EPI). A significant difference was detected in the serum amylase values between the three groups which may be of limited diagnostic value. Dogs with EPI had values lower than normal while those with diabetes mellitus had values higher than control dogs. No evidence of exocrine pancreatic insufficiency was found in dogs with diabetes mellitus.     

Pharmacologic management in veterinary behavioral medicine.

As our knowledge expands, behavioral pharmacology plays an increasingly important role in behavioral medicine. Drugs traditionally categorized as anxiolytics, antidepressants, anticonvulsants, and hormones may be used to help manage a range of animal behavioral problems. Knowledge of how these agents act in the body and interact with other agents is imperative for safe and efficacious use.