Showing items related by title, author, creator and subject.

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  THE ENVIRONMENTAL AND MUSCLE PHYSIOLOGY OF WINTER-ACTIVE AND WINTER-INACTIVE LIZARDS, SCELOPORUS JARROVI AND SCELOPORUS MAGISTER

  Calder, William A. III; Schwalbe, Cecil Robert (The University of Arizona., 1981)

  Field observations indicated a difference in the ability to locomote at low body temperatures in two closely related species of lizards from very different habitats and with radically different seasonal behavior. I measured the critical thermal minimum (the body temperature at which a cooling lizard just loses the ability to right itself) in both species. The winter-active, montane Sceloporus jarrovi had a significantly lower critical thermal minimum in both summer and winter than the winter-hibernating, lowland S. magister. Critical thermal minima were significantly lower in winter than in summer for both species. To determine a physiological basis for these differences, I examined the activity of myosin ATPase, which plays the limiting role in the velocity of muscle contraction, and the energetics of muscle as reflected by high energy phosphate compounds. Microenvironmental conditions were correlated with behavior, constraints on winter activity, and muscle physiology. Ca²⁺-activated myosin ATPase activity in S. magister of valley bottoms is greater than that in the vertical rock-dwelling S. jarrovi. No seasonal acclimatization occurs in myosin ATPase activity in either species. Changes in the muscle metabolism of hibernating animals has been attributed to the lack of muscular contractions in the dormant animals. I measured levels of phosphorylated compounds in a hindlimb muscle from summer and winter lizards of both species. Significant seasonal changes occur in some of the phosphate compounds in both species even though, within a given season, respective levels of phosphorylated compounds are similar in both species. Phosphorylcreatine and total acid-soluble phosphate levels increased in winter animals of both species. Apparently the high levels of phosphorylcreatine in winter S. magister are not simply due to inactivity; winter-active S. jarrovi contain similar amounts. Seasonal cycling of phosphate compounds may relate more to parathyroid status than to muscle activity. Winter activity in S. jarrovi was site-specific and highly dependent on a favorable microclimate. Winter dormancy in S. magister apparently is not dictated by the severity of the microclimate nor physiological limitations of skeletal muscle, but may be strongly influenced by the thermal inertia of that relatively large species.
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  Foliar Fertilization of Sugarbeets During the Winter Months

  Nelson, John; Abbott, Jim (College of Agriculture, University of Arizona (Tucson, AZ), 1982-01)
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  Arizona Water Resource Vol. 20 No. 1 (Winter 2012)

  University of Arizona. Water Resources Research Center.; Przybylowicz, Stephan; Isaak, Marissa T; Megdal, Sharon (Water Resources Research Center, College of Agriculture, University of Arizona (Tucson, AZ), 2012)

  Global Water Brigades (GWB) is a program under Global Brigades, the largest student-led, non-profit, sustainable development organization in the world. Global Brigades works on a holistic model with disciplines in water, public health, medical, dental, architecture, environmental, law, business, and micro-finance. Students across the U.S., and around the world, start chapters at their universities to mobilize students in projects that empower rural areas in Honduras, Panama, and Ghana to improve their conditions. Water Brigades specifically develops clean water solutions for rural Honduras and Ghana. Throughout the school year, GWB discuss and assess the community. Then, over spring break, the group goes to actually build the water system. GWB work alongside community members and make a one day educational presentation to the local school about the importance of clean water. The UA chapter began in September 2010. Last year, UA only had water and medical disciplines as Global Brigades chapters on campus. Now there are two medical groups, dental, public health and business; and a law brigade is starting.