Alkalinity and Hardness: Critical but Elusive Concepts in Aquaculture

Total alkalinity and total hardness are familiar variables in aquatic animal production. Aquaculturists—both scientists and practitioners alike—have some understanding of the two variables and of methods for adjusting their concentrations. The chemistry and the biological effects of alkalinity and hardness, however, are more complex than generally realized or depicted in the aquaculture literature. Moreover, the discussions of alkalinity and hardness—alkalinity in particular—found in water chemistry texts are presented in a rigorous manner and without explanation of how the two variables relate to aquaculture. This review provides a thorough but less rigorous discussion of alkalinity and hardness specifically oriented toward aquaculture. Alkalinity and hardness are defined, their sources identified, and analytical methods explained. This is followed by a discussion of the roles of the two variables in aquaculture, including their relationships with carbon dioxide, pH, atmospheric pollution, ammonia, and other inorganic nitrogen compounds, phytoplankton communities, trace metals, animal physiology, and clay turbidity. Liming and other practices to manage alkalinity and hardness are explained. Changes in alkalinity and hardness concentrations that occur over time in aquaculture systems are discussed. Emphasis is placed on interactions among alkalinity, hardness, water quality, and aquacultural production.     

Establishment and early productivity of perennial biomass alley cropping systems in Minnesota,USA

In May 2010, alley cropping systems consisting of switchgrass (Panicum virgatum L.), prairie cordgrass (Spartina pectinata Bosc ex Link), an alfalfa (Medicago sativa L.) and intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth and Dewey) mixture, and a native tallgrass-forb-legume polyculture, planted between multi-row strips of poplar hybrid ‘NM6’ (Populus maximowiczii x P. nigra) and willow cultivar ‘Fish Creek’ (Salix purpurea) were established at Empire and Granada, Minnesota, USA. Crop establishment and productivity were characterized for each species over two growing seasons and at two distances from the tree-crop interface. Prairie cordgrass and the native polyculture were among the most productive herbaceous crops at both sites, averaging between 7.1 and 11.9 Mg DM ha^?1, and have shown no evidence of competition for resources along the tree-crop interface thus far. Basal area (BA) was similar at Empire for NM6 (1,744 mm² tree^?1) and Fish Creek (1,609 mm² tree^?1), but was greater for NM6 (1,045 mm² tree^?1) than Fish Creek (770 mm² tree^?1) at Granada. Despite this, stand basal area (SBA) was greater for Fish Creek at both sites due to greater planting density. Across species, BA and SBA were greater for trees along the alley than those in center rows at Empire, whereas no difference was observed at Granada. Results suggest that alley cropping provides suitable conditions for establishment of short-rotation woody and certain herbaceous biomass crops, and that some of these crops may be well suited to the alley cropping environment. However, continued research is needed to evaluate crop persistence and productivity as crops and trees mature and the potential for interspecies competition increases.     

Prevention of organ allograft rejection by a specific Janus kinase 3 inhibitor

Because of its requirement for signaling by multiple cytokines, Janus kinase 3 (JAK3) is an excellent target for clinical immunosuppression. We report the development of a specific, orally active inhibitor of JAK3, CP-690,550, that significantly prolonged survival in a murine model of heart transplantation and in cynomolgus monkeys receiving kidney transplants. CP-690,550 treatment was not associated with hypertension, hyperlipidemia, or lymphoproliferative disease. On the basis of these preclinical results, we believe JAK3 blockade by CP-690,550 has potential for therapeutically desirable immunosuppression in human organ transplantation and in other clinical settings.     

Evaluation of a Midhumeral Block of the Radial,Ulnar, Musculocutaneous and Median (RUMM Block) Nerves for Analgesia of the Distal Aspect of the Thoracic Limb in Dogs

Objective: To evaluate a technique for midhumeral peripheral nerve blockade in the dog. Study Design: Cadaveric technique development; in vivo placebo‐controlled, prospective crossover study. Animals: Canine cadavers (n=38) and 8 clinically healthy, adult hound dogs. Methods: A technique for peripheral block of the radial, ulnar, musculocutaneous, and median nerves (RUMM block) was evaluated using cadaver limbs. Eight purpose‐bred, research dogs were anesthetized; a RUMM block was performed on each thoracic limb. One limb from each dog randomly received 0.5% bupivacaine and the opposite limb was assigned to receive sterile saline solution as a control. After recovery from anesthesia, skin sensation at selected dermatomes was evaluated for 24 hours using a mechanical stimulus. Weight‐bearing, conscious proprioception, and withdrawal reflex were also evaluated. One month after initial testing, each dog was reanesthetized and each limb received the opposite treatment. Results: Sensory thresholds were significantly increased over baseline measurements when compared with control limbs for all nerves. Complete sensory block was achieved in radial (15/16), ulnar (3/16), musculocutaneous (8/16), and median (11/16) nerves, using a mechanical stimulus of analgesia. Complete simultaneous block of all nerves was only obtained in 1 of 16 limbs. Conclusion: RUMM block resulted in desensitization of the skin in the associated dermatomes for 4–10 hours. Complete sensory block of the dermatomes supplied by the radial nerve was most consistent. Clinical Relevance: RUMM block may be an effective technique to provide adjunctive analgesia for dogs undergoing surgery of the distal aspect of the thoracic limb.     

Causes of death or reasons for euthanasia in military working dogs: 927 cases (1993-1996)

OBJECTIVE: To determine causes of death or reasons for euthanasia in a population of military working dogs. DESIGN: Retrospective study. ANIMALS: 927 military working dogs. PROCEDURE: Records of all military working dogs that died during the period from 1993 to 1996 were evaluated for cause of death or reason for euthanasia by review of necropsy and histopathology reports, death certificates, and daily clinical treatment sheets. A single primary cause of death or euthanasia was determined. RESULTS: Although sexually intact male dogs were more numerous in the study population, castrated male dogs typically lived longer than spayed females or sexually intact males. Leading causes of death or euthanasia (76.3% of all dogs) were appendicular degenerative joint disease, neoplasia, spinal cord disease, nonspecific geriatric decline, and gastric dilatation-volvulus. Compared with German Shepherd Dogs, Belgian Shepherd Dogs were at increased risk for death attributable to neoplasia, behavior, and respiratory tract disease. German Shepherd Dogs had nearly twice the risk for death associated with spinal cord diseases, compared with Belgian Shepherd Dogs. CONCLUSIONS AND CLINICAL RELEVANCE: For most military working dogs, death or euthanasia results from a few diseases commonly associated with advanced age. Some breed differences in risk for these diseases may exist, which clinicians should consider in the procurement and long-term management of these dogs.     

Renal adenocarcinoma, hepatocellular carcinoma, and pancreatic islet cell carcinoma in a binturong (Arctictis binturong).

A 19-yr-old binturong (Arctictis binturong) with acute upper respiratory disease was euthanized. Postmortem findings included hepatocellular carcinoma, pancreatic islet cell carcinoma, and renal adenocarcinoma with metastasis to the spleen, pleura, and pericardium. A link between primary hepatic and renal neoplasms has been noted in older humans.     

Inheritance of fenvalerate and carbofuran resistance in colorado beetles—Leptinotarsa decemlineata (Say)—from North Carolina

Progeny from reciprocal F1 crosses and F1 backcrosses between fenvalerate-resistant and fenvalerate-susceptible Colorado beetles, Leptinotarsa decemlineata (Say), and between carbofuran-resistant and carbofuran-susceptible Colorado beetles were bioassayed to investigate the mode of inheritance of resistance to these chemicals. Bioassays of progeny from these crosses indicate that resistance to fenvalerate is inherited in a semi-recessive, sex-linked manner and carbofuran resistance is inherited in a partially dominant autosomal fashion. Log concentration/probit mortality lines and chi-square tests, however, indicate that multiple genes may be involved in resistance to both insecticides.     

Insecticide resistance patterns among colorado potato beetle,leptinotarsa decemlineata (Say) (Coleoptera: chrysomelidae), populations in north carolina

A residual bioassay was used to determine insecticide susceptibility in populations of Colarado potato beetle, Leptinotarsa decemlineata (Say), in eastern North Carolina. Mean bioassay mortalities were subjected to correlation analysis to assess patterns of resistance among tested insecticides. Within insecticide classes, cross-resistance patterns were observed between carbaryl and carbofuran (carbamates), fenvalerate and permethrin (pyrethroids), and among azinphosmethyl, methamidophos, and phosmet (organophosphates). Significant associations between insecticides from different insecticide classes were concluded to be due to multiple resistance. Knowledge of multiple and cross-resistance patterns are discussed in relation to the bioassay as a tool for monitoring insecticide resistance.