Improved Types of Sheep for The Southwest; With a Chapter on the Sheep and Tunis and Algeria
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Other TitlesThe Sheep and Tunis and Algeria
Series/Report no.Bulletin (University of Arizona, Agricultural Experiment Station) No. 69
DescriptionThis item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
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Chronic Norepinephrine Suppression Induces a Compensatory B-Cell Adaptation that Enhances Insulin Secretion after Alleviation of the Catecholamine Inhibition in Fetal SheepChen, Xiaochuan (The University of Arizona., 2012)Placental insufficiency-induced intrauterine growth restriction (IUGR) increases risk of mortality and morbidity in newborn infants and domestic animals. IUGR fetuses are typically exposed to prolonged hypoxemia, hypoglycemia, and hypercatecholaminemia, which results in perinatal pancreatic β-cell dysfunction. Recent evidence indicates that chronic exposure to norepinephrine in utero suppresses insulin secretion through α2-adrenergic receptors (ARs), but if the adrenergic actions are blocked compensatory hyper insulin secretion response is observed in the IUGR sheep fetus. In the current studies, we demonstrate that chronic NE exposure alone can produce the compensatory enhancement of β-cell responsiveness following termination of a chronic NE infusion. In the fetus NE was continuously infused at 1-4 μg/min for seven days starting at 131 days of gestational age (term = 145 days). During treatment, NE infused fetuses had higher (P < 0.05) plasma NE concentrations and lower (P < 0.01) insulin concentrations than vehicle infused control fetuses. Glucose stimulated insulin secretion (GSIS), which measures β-cell function, prior to NE treatment was not different between treatments. However, insulin concentrations during hyperglycemic steady state period of GSIS studies and area under the curve of glucose-potentiated arginine-induced insulin secretion were higher (P < 0.01) than control values and this augmentation was confirmed at 3 hours, 24 hours, and five days in NE-infused fetuses after discontinuing the infusion. Pancreatic islets isolated within 10 hours post NE infusion had lower (P < 0.05) mRNA expression of α1D (58%), α2A (43%), α2C (42%), α1 (67%) adrenergic receptors (ARs), and uncoupling protein 2 (40%) compared to islets from controls. Isolated islets from NE-infused fetuses 5 days after NE treatment had lower (P < 0.05) inhibitory responsiveness from NE and a greater (P < 0.05) maximal insulin release with glucose simulation in static incubations compared to controls. These findings show that following chronic NE exposure insulin secretion responsiveness was augmented and was coupled with desensitized adrenergic signaling. Moreover, this compensatory β-cell enhancement persists for days indicating chronic NE exposure permanently alters β-cell responsiveness.
Chronic Norepinephrine Exposure and Whole Blood Detection in Fetal SheepNajam, Aishah (The University of Arizona., 2012-05)Placenta insufficiency results in decreased nutrient supply between the mother and fetus, which induces hypoxemia and hypoglycemia in the fetuses causing intrauterine growth restriction. The fetus increases circulating norepinephrine concentrations in response to this stress, which can cause adrenergic receptor desensitization. The aim of this study was to determine what adrenergic receptors were detectable in fetal whole blood mRNA and to determine whether tissue desensitization manifested in the form of low adrenergic receptor mRNA concentrations. Three of the nine adrenergic receptor subtypes (α2A, β1 and β2) were detectable in RNA extracted from fetal whole blood of control and placenta insufficient treatment groups. Of these three, adrenergic receptor α2A was expressed in the greatest concentration and was chosen for further study. In placenta insufficient fetuses adrenergic receptor α2A mRNA concentrations were 73% lower than the control group. We also measured adrenergic receptor α2A mRNA in fetuses without an adrenal medulla, which were not responsive to hypoxemia-induced elevation of norepinephrine. These placental insufficient fetuses were no different from the controls and therefore, the evidence supports the increase of norepinephrine, rather than the hypoxic conditions, as the cause of desensitization in whole blood samples.
Desert bighorn sheep forage relationships in the Virgin Mountains, Arizona.Morgart, John Raymond. (The University of Arizona., 1990)Twelve desert bighorn sheep (Ovis canadensis nelsoni) were captured 12-14 November 1979 in the Black Mountains, western Arizona, and translocated to a 283 ha enclosure in the Virgin Mountains, northwestern Arizona. I studied habitat and foraging relationships of the population from November 1979 to December 1981. My objectives were to investigate productivity, group characteristics and habitat use, intraspecific comparisons of diet, diet overlap with cattle, forage availability and use, diet diversity, and plant quality. Seven and 8 females in the enclosure had lambs in 1980 and 1981, respectively. Mean group size was largest in spring, coincident with the peak of lambing. The number of mixed sex groups decreased in spring and summer when adult females did not associate with adult males. The number of mixed sex groups were highest in fall and winter due to rut and post-rut aggregations. The 4 vegetation associations in the enclosure were used in proportion to availability except by adult females and lambs in spring-summer 1981. Grasses, forbs, and browse were equally important in the annual diets of bighorn sheep; the use of succulents was secondary. Browse and grasses comprised most of the cattle diet (45.4% and 40.1%, respectively) followed by forbs (13.1%). Intraspecific differences in bighorn sheep diets were not significant. Bighorn sheep and cattle diets did not overlap significantly and bighorn sheep diets were more diverse. Bighorn sheep did not eat 8 plant species in proportion to their occurrence in the enclosure. Habitat conditions and behavior patterns of bighorn sheep in the enclosure were similar to free-ranging populations. However, range conditions in the enclosure were excellent, predators were controlled, and potential competitors were excluded. The reproductive potential of desert bighorn sheep was obtained. Although I confirmed a relationship between bighorn sheep diet and plant nutrition, no intraspecific differences in seasonal nutrition requirements were established. In addition, dietary overlap between bighorn sheep and cattle was not significant; these data have important management implications for future bighorn sheep introductions onto traditional livestock grazing areas.