Animal & Avian Sciences Theses and Dissertations
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Item The interaction between a parasitic barnacle, Loxothylacus panopaei (Cirripedia, Rhizocephala), and three of its crab host species (Brachyura, Xanthidae) along the east coast of North America.(1993) Alvarez, Fernando; Reaka-Kudla, Marjorie; Animal & Avian Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)Rhizocephalan barnacles parasitize primarily decapod crustaceans (Bocquet-Vedrine 1968, Overstreet 1983). The principal effect of the parasites is often the permanent sterilization of the hosts (Bocquet-Vedrine 1972, O'Brien & Van Wyk 1984). Regardless of the processes involved, the end result of the infection is the creation of non-reproductive individuals that will use resources that otherwise would be available to the healthy traction of the host population. The potential impact on the host population then resides in the accumulation of sterile resource-using individuals in each generation. Prevalences of barnacles on anomuran and brachyuran crabs have been reported in a number of studies (e.g., Walker 1985, Hawkes et al. 1986, Johnson et al. 1986, Wardle & Tirpak 1991 ). Rhizocephalan infections can reach very high levels locally, suggesting that entire host populations may have a greatly reduced reproductive capacity. However, in most host species, the pattern of distribution of parasites is not uniform throughout the host's range. I examined the crab-rhizocephalan interaction using the system composed by the barnacle Loxothylacus panopaei and three of its crab host species: Panopeus lacustris, Eurypanopeus depressus, and Rhithropanopeus harrisii, occurring along the east coast of the North America. Through experimental infections conducted in the laboratory, it was determined that B. harrisii of a wide range of sizes could be infected by L. panopaei. The complete life-cycle of the parasite was manipulated in the laboratory. Neither host molting frequency nor host molt increments differed significantly between parasitized and control crabs. Host survival was significantly reduced during the parasite's developmental period; the heaviest mortality of the host occurred in the megalopal stage.Item MOLECULAR ANALYSIS OF CYCLOPHILIN FUNCTION IN THE YEAST SACCHAROMYCES CEREVISIAE(1994) Davis, Edward S.; Brennan, Miles S.; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)The cyclophilins are a family of proteins first identified as receptors for cyclosporin A (CsA), a cyclic peptide of fungal origin. CsA inhibits T-lymphocyte activation, and is thus a potent immunosuppressant. Although cyclophilins are ubiquitous, and highly conserved, among eukaryotes, their normal physiological functions are unknown. As the receptors for CsA, cyclophilins might be involved in regulating signal transduction pathways. Cyclophilns also have peptidyl-prolyl, cis-trans isomerase (PPIase) activity in vitro, suggesting a role in protein folding in vivo. While CsA inhibits cyclophilin's PPIase activity, this inhibition is insufficient to account for the pharmacological activity of CsA. Therefore, previous results cannot be readily synthesized into a model for cyclophilin function. The goal of this project was to define and characterize physiological roles of cyclophilins using the yeast S. cerevisiae. Three S. cerevisiae cyclophilin genes were cloned and inactivated by insertional mutagenesis. I demonstrated that one, CPR3, is necessary for the efficient metabolism of non-fermentable carbon sources. The CPR] gene product, Cpr3, is localized to the mitochondrial matrix, and a truncated version of Cpr3 expressed in bacteria binds CsA. CPR3 inactivation does not significantly compromise the induction of transcription of two nuclear cytochrome genes. Thus, Cpr3 is not necessary for the signal transduction pathway governing cytochrome gene expression. To identify biochemical targets of Cpr3, I demonstrated that inactivation of a mitochondrial lactate dehydrogenase is insufficient to account for the growth defect of cpr3 mutants. An exhaustive search for high-copy suppressors of the growth defect of cpr3 mutants led to the identification of a novel gene, JEN1, that suppresses the growth defect at elevated temperature. JEN1 encodes a protein that is probably a lactate transporter, and thus not a direct biochemical target of Cpr3. A dominant mutation in a nuclear gene, JEN2, suppresses the growth defect of cpr3 mutants on lactate at 30°C and 37°C. JEN2 might encode a direct biochemical target of Cpr3. In summary, the cyclophilin, Cpr3, plays a general role in the efficient function of yeast mitochondria, and presents an excellent model system for studying cyclophilin function.Item Dietary Control of Cystinuria in Maned Wolves (Chrysocyon Brachyurus)(1998) Boniface, Jennifer; Soares, Joseph H., Jr.; Avian and Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)The maned wolf (Chysocyon brachyurus) is an endangered South American species of canid, whose numbers in both the wild and captivity are threatened in part by a condition called cystinuria. In humans and rats, cystinuria is caused by mutations of the rBAT gene, expressed in intestinal mucosal cells and renal tubules. In dogs, only renal tubules are affected. Cystinuric individuals exhibit impaired capacity for reabsorption of the sulfur amino acid cystine. Consequently, excess cystine accumulates in the urine. In acidic conditions, cystine may precipitate into uroliths, potentially obstructing the urethra and ultimately causing bladder rupture or kidney damage. Treatments include medical management and dietary modification. Test diets differing only in levels of cystine were fed to 15 maned wolves in a cross-over design. Apparent digestibility calculations suggest the diets were well received, well utilized and improved fecal quality. The low cystine diet significantly reduced urinary excretion of cystine (P<0.05). Mean urinary concentrations of cystine were 341±45.87 mg/L or 2.78±0.326% total urinary nitrogen for the low cystine diet; and 475.8± 47.80 mg/L or 4.01± 0.342% for the high cystine diet. Water balance studies was determined three maned wolves, using orally administered deuterium oxide. Urine samples were collected daily for seven days, purified by sublimation, and analyzed by infrared spectrometry. It was determined that total body water, water turnover rate and body composition were 17.2 L, 2.3 L/d, and 20.5% fat; 79.5% lean, respectively. These results are comparable to published values for dogs.Item Physiological and Behavioral Effects of Handling and Restraint of the Ball Python (Python regius) and the Blue-Tongued Skink (Tiliqua scincoides)(1992) Kreger, Michael Douglas; Mench, Joy A.; Poultry Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Reptiles are handled during transport, veterinary care, education programs, and as companion animals. This study investigated corticosterone levels (CS), heterophil/lymphocyte ratio (H/L), and behavioral responses to routine handling in the ball python (Python regius) (n=4) and the blue-tongued skink (Tiliqua scincoides) (n=3). We validated the RSL I125 Corticosterone Kit for rodents for parallelism and recovery, and found this to be a precise and highly specific means of CS measurement in reptiles. To determine the optimal blood sampling time, animals were sampled throughout a 24-hour cycle under two different light regimens, one a 12L:12D and one in which a red light was on during the dark period. The diurnal pattern of CS did not differ as a result of light regimen. Python peak CS levels occurred at 2400 hours during the peak locomotor activity period and at 1200 hours when body temperature was highest, while skinks showed no significant CS rhythm. Heterophil/lymphocyte ratio values indicated that cardiac puncture did not cause chronic stress although it may be an acute stressor. Animals were then handled gently, manually, or were container restrained (CR) for 10 minutes. Although skink CS was unaffected by treatment, CR caused an elevated level of CS in pythons which may indicate short-term stress. There were no differences in H/L ratio or changes in activity level in either species. Brief periods of routine handling of the study species in captivity thus did not cause chronic stress as measured by CS, H/L ratio, and activity parameters.Item The Characterization and Cryopreservation of Striped Bass (Morone saxatilis) Semen(1999) Jenkins, Karen; Curry Woods III, L.; Department of Avian and Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)