Now showing items 1-7 of 7

• #### Blood organochlorines, immune function and health of free-ranging northern fur seal pups (Callorhinus ursinus)

This study examined organochlorine (OC) contaminant levels in blood and milk along with immune function and health of northern fur seals ( Callorhinus ursinus) from St. George Island, Alaska. This portion of the Pribilof Islands breeding stock has undergone a long-term decline between 4 and 6% per year for unknown reasons. To examine the possible role of neonatal OC exposure on health, two cohorts of pups (69 total) and 33 matched periparturient dams were captured for blood and milk sample collection. From the second cohort of 49 neonates, 43 were re-sampled 29 to 51 days later. OCs were extracted from whole blood and milk to identify 15 polychlorinated biphenyl (PCB) congeners and 4 metabolites of dichloro-diphenyl-trichloroethane by high performance liquid chromatography. Peripheral blood lymphocytes were isolated and cryopreserved for in vitro lymphoproliferative immunoassays. These cellular function assays, along with complete blood cell counts, growth rates and survival through the early developmental period, were used as indicators of health status. Humoral immune function was assessed by in vivo antibody responses to tetanus vaccination. Mean blood levels of PCBs were higher in neonate samples than in pups one to two months old. Seven of the eight congeners detected in blood were higher (lipid weight) in neonate blood than in dam blood or milk. First-born neonates were exposed to higher levels of OCs from ingested milk and had higher blood levels of OCs than neonates of older, multiparous dams. Higher OC exposure in neonates was correlated to higher blood OC levels and poorer lymphoproliferative responses as well as lowered serum. retinol and thyroxine. Higher proportions of pups born to old dams developed tetanus antibodies compared to the pups of young dams. Higher OC exposure and poor immune responses in first-born pups may indicate a higher risk of secondary morbidity and mortality than for pups born to multiparous dams but an affect on growth rate or survival to midway through the nursing period was not detected. Evidence of substantial OC contaminant exposure at a critical period of development for the immune system must be considered as a potential contributing factor to reduced post-weaning survival.
• #### Brucella suis type 4 in foxes and their role as reservoirs/vectors among reindeer

Field and laboratory studies were conducted to test the hypotheses that (1) the reindeer/caribou organism, Brucella suis type 4, is incidentally transmitted to reindeer predators such as foxes but does not cause reproductive disease in them, and (2) infected predators such as foxes are terminal hosts and do not serve as reservoirs of infection for reindeer. In field collections, serologic prevalence of brucellosis was similar for male and female foxes (Vulpes vulpes and Alopex lagopus). B. suis type 4 was isolated from female Vulpes and Alopex. No association between reproductive status of foxes and brucellosis infections was observed. Serologic titers in Vulpes experimentally infected by oral exposure to Brucella suis type 4 were detected first by the standard tube and plate agglutination tests which were followed by the buffered Brucella antigen, rivanol, and complement fixation tests. Brucella suis type 4 was isolated from the feces 4 to 6 days post-exposure (PE) and from the oral cavity for as long as 3 weeks PE in Vulpes challenged with 10$\sp9$ or 10$\sp{11}$ colony forming units. Brucella suis type 4 was isolated frequently from regional lymph nodes in the head up to 18 weeks PE, and from only more distant nodes at 22 and 66 weeks PE. Organisms did not localize in the reproductive tract. Clinical effects of brucellosis in Vulpes experimentally-infected were not observed. Pathologic lesions were not detected in the male and non-gravid female reproductive tract. Due to breeding failure, effects of Brucella suis type 4 on the pregnant fox reproductive tract were not determined in experimental infections. Gross and microscopic pathology was limited to lymph nodes. Fox to fox transmission attributed to aerosols from products shed by infected foxes occurred readily. Transmission from Vulpes to lemmings (Dicrostonyx rubricatus) that were exposed to urine from infected fox occurred frequently. Transmission from infected Vulpes to two reindeer (Rangifer tarandus) occurred under conditions of close confinement. Ingestion of organisms passed mechanically in the fox feces was considered the probable source of infection. Fox saliva containing Brucella was also implicated in transmitting the organism through bites or aerosols.
• #### Central Nervous System Regulation Of Metabolic Suppression In Arctic Ground Squirrels

The main focus of this dissertation is central nervous system regulation of metabolic suppression in hibernating mammals in general, and the Arctic ground squirrel (Urocitellus parryii) as a model for seasonal hibernation. Hibernation is a unique physiological, morphological, and behavioral adaptation to overcome the periods of resource limitation. Metabolic suppression seen in torpor during hibernation has several biomedical applications. A multitude of studies have revealed the role of the central nervous system in regulating hibernation, including a role for neurotransmitters and neuromodulators. Previous studies have shown that the neuromodulator adenosine mediates altered thermoregulation during induction of torpor in facultative hibernators, but it is not clear how adenosine influences torpor in seasonal hibernators. The main focus of the current project was to test the hypothesis that a seasonal change in purinergic signaling is necessary for the onset of spontaneous torpor in the Arctic ground squirrel. My dissertation reports that adenosine meets all of the necessary requirements for an endogenous mediator of torpor in the hibernating Arctic ground squirrel. A progressive increase in sensitivity to adenosine A 1 receptors mediated signaling defines the seasonal transition into the hibernation phenotype. I show that adenosine A1 receptor activation is necessary and sufficient to induce torpor in the Arctic ground squirrel. Glutamate is an excitatory neurotransmitter which is widely studied in hibernation research. My dissertation demonstrates that N-methyl-D-aspartate type glutamate receptors, located in the periphery or circumventricular organs, are involved in inducing arousal from torpor in the hibernating Arctic ground squirrel. This dissertation also presents evidence that dietary restriction sensitizes adenosine A1receptors in rats through an increase in surface expression in thermoregulatory regions of the brain (hypothalamus). This contributes to the decline in body temperature and respiratory rate in animals subjected to a restricted diet, which mimics a torpor-like effect.
• #### Detection and control of brucellosis in reindeer vaccinated with Brucella suis biovar 3

The objective of this research was to provide a vaccine for the control of brucellosis in reindeer, that allows serologic discrimination between vaccinated and infected animals. Three vaccines were tested: (1) Brucella suis 1, (2) B. suis 3, and (3) A rough mutant of the infective strain, B. suis 4. All were heat-killed and prepared in Freund's incomplete adjuvant. Each vaccine was administered to four animals. All vaccines stimulated the production of high levels of antibody in Rangifer that were maintained for the 483-day experiment. Significant delayed-type hypersensitivity reactions were seen in all vaccinated Rangifer. Both B. suis 1 and B. suis 3 vaccines allowed serologic discrimination between vaccinated and infected Rangifer. This was accomplished by means of an indirect ELISA (enzyme-linked immunosorbent assay). This test used whole cell B. melitensis and B. abortus as A and M-dominant antigens. Distinction could be made between vaccinated and infected reindeer based on a percentage difference in spectrophotometric abosorbance values obtained with these antigens. The B. suis 3 vaccine provided the best discrimination. Eighty-nine percent of 117 reindeer were correctly classified as either B. suis 3-vaccinated or B. suis 4-infected. Discrimination between vaccinated and infected reindeer was sufficient to allow assessment of the prevelance of brucellosis and vaccinated herds. In addition, the ELISA was more sensitive than standard agglutination tests in identifying reindeer with exposure to B. suis. The B. suis 3 vaccine was further evaluated in a challenge of 7 vaccinated reindeer. The vaccinated group consisted of 5 pregnant adults and 2 8-month-old female calves. These reindeer were challenged with $3.16\times10\sp7$ colony forming units of B. suis 4 at 63 days post-vaccination. Five pregnant adults and 1 female calf served as experimental controls. B. suis 4 was isolated from 3 of 7 vaccinated reindeer (43%) at the time of necropsy. B. suis 4 was isolated from the aborted fetus of 1 of the infected vaccinates. Another infected vaccinate bore a healthy calf for which B. suis 4 could not be isolated. All control reindeer were infected and all 5 adults aborted. B. suis 4 was isolated from all 5 fetuses. The B. suis 3 vaccine provided significant protection against infection and abortion in reindeer challenged with B. suis 4.
• #### Epizootic Of Beak Deformities In Alaska: Investigation Of An Emerging Avian Disease

The sudden appearance of morphological abnormalities in a wild population is often associated with underlying ecological disturbances, including those related to introduction of new pathogens or pollutants. An epizootic of beak deformities recently documented among Black-capped Chickadees (Poecile atricapillus) and other resident bird species in Alaska has raised concern about underlying causes. This dissertation describes results from several recent studies of what we have termed "avian keratin disorder." The primary objectives of the research were to characterize the physiology and pathology of beak deformities and to address specific ecological questions related to this emerging avian disease. In a study of beak growth rates in captive chickadees, I determined that accelerated epidermal growth is the primary physical mechanism by which beak deformities develop and are maintained. Affected birds also exhibited high rates of mortality and skin lesions, suggesting that this disorder significantly compromises individual health. I used radiography, histopathology, and electron microscopy to describe the pathology of avian keratin disorder. As part of this effort, I established baseline information about normal passerine beak and claw structure and developed methods for processing hard-cornified tissues. The suite of lesions that I observed in affected chickadees does not correspond with any known avian diseases, suggesting the presentation of a novel disorder in wild birds. In addition, the detailed characterization of gross and microscopic changes has allowed me to eliminate a number of likely etiologies, including nutritional problems, microbial pathogens, and select toxicants. As a complement to diagnostic pathology, I conducted field studies to investigate possible causes and patterns of occurrence of beak deformities. I used stable isotope analysis to investigate the association between diet and beak deformities. I found that winter dietary patterns differed between chickadees with normal beaks and those with beak deformities, but that such differences are more likely a result than a cause of avian keratin disorder. My field research on Northwestern Crows in Alaska confirmed high prevalence of a nearly identical condition to that observed in chickadees. These findings indicate that avian keratin disorder affects multiple, ecologically-distinct species across a large geographic area. Together, the studies presented in this dissertation provide new insights and identify priority research areas for a rapidly emerging disease in wild birds.
• #### Investigations of health status and body condition of harbor seals (Phoca vitulina) in the Gulf of Alaska

Harbor seal (Phoca vitulina) declines during the past 20 years in the Kodiak Island and Prince William Sound regions contrast with stable or slightly increasing populations in southeastern areas of Alaska. Aspects of health status and body condition were investigated to test the hypothesis that these declines were driven by nutritional limitation, and to determine whether recent differential population trajectories among Kodiak Island, Prince William Sound, and southeast Alaska could have health-related components. For comparisons between 1992-96, three aspects of health status were examined; blood chemistry, blubber distribution and quantity; and blubber quality. Clinical ranges of plasma chemistries and hematologies were established for free-ranging seals in the Gulf of Alaska. Significant handling, individual, and seasonal effects were found on many blood parameters that could bias interannual and interregional comparisons if not incorporated in models. Based on statistical modeling, some seals showed more clinically aberrant values than expected by chance, but these were not clumped among regions or years. Differences existed in interannual blood chemistry and hematology patterns between juveniles and adults. Likewise, there were regional differences in blood chemistries of unknown significance. Morphometric indices were poor indicators of condition defined as size-at-age or blubber content. This was related to patterns of blubber distribution and variability, which differed between males and females. Blubber quality, measured as lipid content, did not substantially vary seasonally or between geographic regions, but blubber from Prince William Sound was less hydrated than blubber from non-declining areas. There were no detectable differences in body condition of seals from the Gulf of Alaska sampled during 1963/64 (pre-decline), 1976-78 (during decline) and 1995-96. However, sample sizes were small and patchily distributed throughout locations and years. Thus, the likelihood of detecting body condition changes in response to environmental conditions was poor. Body condition was not substantially different among seals from Prince William Sound, Kodiak Island and southeast Alaska measured during 1993-96. However, interannual blood chemistry and body condition patterns were evident among Prince William Sound seals that may have been associated with environmental conditions.
• #### Pathophysiology of infections by the gastric trichostrongylid Obeliscoides in a rabbit model system

The gastric trichostrongylid parasite Obeliscoides sp. was isolated from Alaskan snowshoe hares (Lepus americanus) and passaged 3 times in laboratory rabbits (Oryctolagus cuniculus). Despite its low fertility, the isolate persisted, often as occult infections, for up to 45 weeks and produced physiologic effects in clinically normal rabbits. Prominent eosinophilic and hyperplastic lesions of the gastric mucosa occurred during post-inoculation weeks (PIW) 2-15, while mononuclear aggregations were seen in older infections. Gastric lesion severity was directly related to size of the Obeliscoides population, which declined over time and was smaller in secondary infections. Anorexia occurred within 3 weeks of infective larval inoculation in 12 (of 21) primary and 2 (of 10) secondary infections. Serum total protein, albumin, and the A/G ratio were significantly reduced in anorectic infected rabbits compared to fasted uninfected rabbits. Fecal N excretion was significantly increased between PIW 1 and 5 in rabbits with primary infections, and during PIW 1 and 2 for those with secondary infections. Nitrogen absorption was enhanced during PIW 5-15 of primary infection. Serum gastrin concentrations, determined for the first time in Obeliscoides-infected rabbits by radioimmunoassay, were significantly elevated in primary infections during PIW 6 and 7, while hypokalemia was apparent during PIW 5. Hypermagnesemia occurred in both primary and secondary infections between PIW 8 and 15. Other serum constituents and concentrations of N, Ca and P in the gastrointestinal tract and feces remained largely unchanged. Total mean retention time (TMRT), 31.8 h, and GI turnover time (GITT), 26.3 h, of the fiber component (determined with Ce-141-marked fiber $>$355 microns) were significantly prolonged in secondary infections during PIW 16 to 26. TMRT (53.0 h) and GITT (57.0 h) of the liquid component (using Cr-51 EDTA), were determined for the first time in rabbits, and were not significantly changed by Obeliscoides infection. Persisting populations of this Obeliscoides isolate caused physiologic and pathologic alterations in clinically healthy rabbits. Because these effects were similar to those seen in ruminant Ostertagia spp. infections, this laboratory model could be useful in understanding the pathophysiology of costly production losses that occur in parasitized commercial livestock.