Effect of Holding and Packing Conditions on Hemolymph Parameters of Freshwater Prawns,Macrobrachium rosenbergii,during Simulated Waterless Transport

Preliminary market research has identified an unfulfilled market potential for live freshwater prawn, Macrobrachium rosenbergii, in urban areas of the USA and Canada. Truck transport is effective but requires shipment of large numbers of prawns to be economically feasible. Most retail markets are ill‐equipped to hold large quantities for subsequent live sales. Air‐freight of smaller quantities has potential but water weight limits its application. Shipping of live aquatic animals in waterless environments has been reported for some finfish and crustaceans. This project utilized biochemical characteristics of prawn hemolymph as measures of sublethal stress during simulated transport. Six trials were conducted to evaluate the effects of different variables involving preshipment holding conditions, acclimation prior to shipping, and conditions inside the shipping container. Trial 1 compared animals shipped in water with those in a non‐aqueous environment. Trial 2 compared three chilling rates (slow chill, fast chill, and no chill). Trial 3 evaluated different holding protocols including fed versus unfed, reduced pH, increased water hardness, and salinity. Trial 4 evaluated the addition of ammonia scavengers to the transport containers. Trial 5 evaluated the use of carbon dioxide scavengers and an anesthetic, AQUI‐S®. Trial 6 used the best results of Trials 2–5 in a combination of “Best Management Practices” (BMP) over extended time periods. Treatments had either three or four replications using Styrofoam boxes, each packed with six individually tagged prawns. Presoaked wood‐shavings and ice packs were used to keep the boxes moist and cool. The boxes were then sealed in individual oxygenated plastic bags. Trials 1–5 were conducted for 16 h and Trial 6 had separate boxes which were opened at 16, 24, and 32 h. Baseline hemolymph samples were taken prior to packing and from prawn alive at the end of all trials. Hemolymph variables included pH, pO₂, pCO_2, HCO₃, tCO₂, calcium, ammonia, osmolality, glucose, lactate, total protein, magnesium, calcium, and potassium. Percent survival and weight loss were also measured. Results of Trial 1 indicated that compared to transport in water, non‐aqueous environment significantly increased (P≤ 0.05) hemolymph levels of CO₂ and ammonia, and significantly reduced levels of oxygen. In Trial 2, survival in the Slow Chill treatment was significantly higher than in the No Chill treatment, although hemolymph characteristics were not impacted. In Trial 3 prawns held in tanks with added salt (17 ppt) had the highest survival and lowest hemolymph concentration of ammonia and partial pressure of CO₂. The ammonia scavengers in Trial 4 had no significant impact on survival or hemolymph variables. The CO₂ scavengers and anesthetic in Trial 5 had no statistically significant impact on survival. The BMP of Trial 6 consisted of, in the following order, holding in 17 ppt marine salt mix, slow chilling, anesthetic (AQUI‐S) dip, and adding limewater (Ca(OH)₂ + H₂O) to the shipping box as a CO₂ scavenger. In Trial 6, after 32 h of simulated “waterless” transport, prawns in the BMP treatment had significantly higher survival (96%) than prawns in the Control treatment (58%). The BMP prawns also had significantly higher partial pressures of oxygen and lower partial pressures of CO₂ in the hemolymph.     

Potassium homeostasis and membrane transport

Cytosolic K⁺ activity in plant cells is about 80 mM and is maintained during moderate K⁺-deprivation. It decreases to much lower values only in extreme K⁺-deficiency. In contrast, the vacuolar K⁺ concentration responds directly to the K⁺ supply and can fall to very low values in severely K⁺-deprived cells. However, there is good evidence for an upper limit for vacuolar K⁺ concentration which is different in roots and leaves. Understanding of the molecular basis of active and passive K⁺ transport in plants has increased enormously in recent years but the role of individual transporters in uptake has still to be fully resolved, as has their regulation in relation to the maintenance of cytosolic and vacuolar K⁺ concentrations. In particular, the inverse relationship between the rate of K⁺ uptake and internal K⁺ concentration that was established over 25 years ago has still not been credibly explained at the molecular level.     

Killing of Streptococcus uberis by bovine neutrophils following growth in chemically defined media

Following growth in a chemically defined medium (CDM), five strains of Streptococcus uberis were tested for their ability to survive killing by bovine neutrophils. Strains 0140J, ST10, EF20 and C221 were easily killed, whereas strain C197C was highly resistant. The ability of strain 0140J to resist phagocytosis and killing was increased by supplementation of the growth medium with milk whey, casaminoacids, casein, or, to a lesser extent, bovine serum. Supplementation of the growth medium with yeast extract or bovine serum albumin did not affect the resistance of this strain. Following growth in CDM supplemented with casein, strains ST10 and C221, like strain 0140J, were significantly more resistant to killing by neutrophils. The resistance of strains EF20 and C197C was unaffected by the addition of casein to the medium; strain EF20 remained susceptible and strain C197C highly resistant to killing. The effect of supplementing the growth media with components other than casein was only studied for strain 0140J. Decapsulation of strains C197C, ST10 and 0140J, grown in CDM + casein, with type-X hyaluronidase did not significantly affect their ability to survive in the presence of bovine neutrophils.     

The prevalence of lice (Bovicola ovis) infested sheep flocks in Western Australia (1987–1993)

SUMMARY The proportion of wool bale brands with a positive test for sheep lice in baled wool decreased from 29.5% in 1987/88 to 23.2% in 1990/91 before increasing to 38.2% in 1992/93. Changes in the proportion of wool bale brands with a positive test for lice were highly correlated with changes in the Wool Market Price Indicator. The increase in the proportion of positive lice tests since 1990/91 was associated with an increase in failures to eradicate lice from flocks. These failures were partly a consequence of the reduced use of lousicidal treatments, the development of resistance to synthetic pyrethroid chemicals and an increase in the transmission of lice between flocks.     

BOLD responses reflecting dopaminergic signals in the human ventral tegmental area

Current theories hypothesize that dopamine neuronal firing encodes reward prediction errors. Although studies in nonhuman species provide direct support for this theory, functional magnetic resonance imaging (fMRI) studies in humans have focused on brain areas targeted by dopamine neurons [ventral striatum (VStr)] rather than on brainstem dopaminergic nuclei [ventral tegmental area (VTA) and substantia nigra]. We used fMRI tailored to directly image the brainstem. When primary rewards were used in an experiment, the VTA blood oxygen level-dependent (BOLD) response reflected a positive reward prediction error, whereas the VStr encoded positive and negative reward prediction errors. When monetary gains and losses were used, VTA BOLD responses reflected positive reward prediction errors modulated by the probability of winning. We detected no significant VTA BOLD response to nonrewarding events.     

Evaluation of a rapid single multiplex microsatellite-based assay for use in forensic genetic investigations in dogs

OBJECTIVE: To develop a set of microsatellite markers, composed of a minimal number of these markers, suitable for use in forensic genetic investigations in dogs. SAMPLE POPULATION: Blood, tissue, or buccal epithelial cells from 364 dogs of 85 breeds and mixed breeds and 19 animals from related species in the family Canidae. PROCEDURE: 61 tetranucleotide microsatellite markers were characterized on the basis of number and size of alleles, ease of genotyping, chromosomal location, and ability to be coamplified. The range in allele size, number of alleles, total heterozygosity, and fixation index for each marker were determined by use of genotype data from 383 dogs and related species. Polymorphism information content was calculated for several breeds of dogs. RESULTS: 7 microsatellite markers could be coamplified. These markers were labeled with fluorescent dyes, multiplexed into a single reaction, and optimized for resolution in a commercial genetic analyzer. The multiplex set was used to identify sires for 2 mixed litters. The test was not species specific; genotype information collected for wolves, coyotes, jackals, New Guinea singing dogs, and an African wild dog could not distinguish between these species. CONCLUSIONS AND CLINICAL RELEVANCE: This set of 7 microsatellite markers is useful in forensic applications (ie, identification of dogs and determination of parentage) in closely related animals and is applicable to a wide range of species belonging to the family Canidae.     

The effects of medetomidine on radial nerve blockade with mepivacaine in dogs

OBJECTIVE: To compare the sensory and motor effects of adding medetomidine to mepivicaine, administered either perineurally or systemically, for radial nerve block in dogs. STUDY DESIGN: Prospective randomized cross-over study. ANIMALS: Six healthy Beagles, aged 18.7 +/- 6.3 months and weighing 10.4 +/- 1.3 kg. METHODS: Dogs were anesthetized briefly with sevoflurane on three separate occasions and received each treatment administered in random order: mepivacaine 5 mg kg(-1) perineurally around the radial nerve with saline 0.01 mL kg(-1) intramuscularly (CONTROL); mepivacaine 5 mg kg(-1) and medetomidine 0.01 mg kg(-1) combined, perineurally with saline 0.01 mL kg(-1) intramuscularly (MEDPN); mepivacaine 5 mg kg(-1) perineurally around the radial nerve with medetomidine 0.01 mg kg(-1) intramuscularly (MEDIM). All nerve blocks were performed with the aid of a nerve locator. Motor effects were evaluated based on the ability to bear weight. Sensory effects were evaluated by the response to a graded-electrical stimulus. These were evaluated at 5-minute intervals for the first hour, and at 10-minute intervals thereafter. Mean intervals were calculated as follows: time to motor block onset, duration of motor block, time to peak sensory block, duration of peak sensory block (i.e. period of no response to maximal stimulus intensity), and duration of residual sensory block (i.e. time to return to baseline sensory function). Treatment means were compared using a one-way analysis of variance for repeated measures and, where significant differences were noted, a Student-Newman-Keuls test was applied; p < 0.05 was considered significant. RESULTS: Medetomidine, administered either systemically or perineurally, significantly prolonged duration of peak motor block, peak sensory block, and residual sensory block compared with CONTROL. CONCLUSION: Medetomidine prolonged sensory and motor blockade after radial nerve block with mepivacaine in dogs. CLINICAL RELEVANCE: Medetomidine may prove to be a useful adjunct to peripheral nerve blockade with local anesthetics.