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71.
Kellar Autumn Devin Jindrich Dale DeNardo Rachel Mueller 《Evolution; international journal of organic evolution》1999,53(2):580-599
Nocturnal geckos are active at body temperatures 10–35°C below the thermal optima for maximum rate of aerobic metabolism of diurnal lizards. Therefore, given ancestral (diurnal) lizard physiology, nocturnality causes a substantial thermal handicap in locomotor performance. In prior studies, we hypothesized that a low minimum cost of locomotion (Cmin) in geckos was an adaptation that increased locomotor endurance capacity at low, nocturnal temperatures. However, Cmin is only part of an integrated system that, in conjunction with the maximum rate of oxygen consumption, sets the maximum speed that can be sustained aerobically (termed the maximum aerobic speed or MAS). We conducted the first phylogenetic analysis of MAS and lizards and found that the greatest changes in MAS, Cmin and (at activity temperatures) in the evolutionary history of lizards all coincided with the evolution of nocturnality in geckos. Geckos active at 15–25°C did not become optimized for nocturnal temperatures, or fully offset the thermal effects of nocturnality by evolving maximal rates of oxygen consumption comparable to diurnal lizards active at 35°C. Geckos did evolve MAS twice that of diurnal lizards running at low temperatures by evolving a remarkably low Cmin. Allometric analysis and phylogenetically independent contrasts of , Cmin, and MAS indicate a 72% evolutionary decrease in , (at activity temperatures) and a 50% evolutionary decrease in Cmin concordant with the evolution of nocturnality in geckos. Experimental measurements show that decreased Cmin in six species of gecko increased MAS by 50–120% compared to diurnal lizards at low temperatures. Thus, geckos sufficiently overcame the near paralyzing effects of nocturnal temperatures, but only offset about 50% of the decrease in MAS resulting from the low maximum rate of oxygen consumption. Although the nocturnal environment remains severely suboptimal, the evolution of a low cost of locomotion in the ancestor of geckos was highly adaptive for nocturnality. We also present a generalized approach to ecophysiological evolution that integrates phylogeny with the causal relationships among environment, physiology, and performance capacity. With respect to a clade, two hypotheses are central to our integrative approach: (1) a change of an environmental variable (e.g., temperature) causes a performance handicap; and (2) evolution of a physiological variable (e.g., minimum cost of locomotion [Cmin]) increases performance in the derived environment. To test the hypothesis that evolution of a physiological variable is adaptive in nature, we suggest determining if individuals in nature perform at levels exceeding the performance capacity of their hypothetical ancestors and if this additional performance capacity is due to the evolution of the physiological variable in question. 相似文献
72.
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74.
Pat. Howard 《e》2009,4(4):e170-e171
75.
Dexamethasone and a metabolite, 9-fluoro-16α-methyl-6β, 11β, 16β-trihydroxy-1, 4-androstadiene-3, 17-dione, were detected in the urine of horses injected parenterally with the parent drug. The structure of the metabolite was elucidated by thin-layer chromatography, infrared spectroscopy, mass spectroscopy and nuclear magnetic resonance spectroscopy. 相似文献
76.
E.Dale Sevier Leland M. Shannon 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,497(2):578-585
A particulate enzyme preparation from horseradish root tissue was shown to catalyze the transfer of 2-acetamido-2-deoxy-d-[14C1]glucose from uridine diphosphate 2-acetamido-2-deoxy-d-[14C1]glucose to an exogenous acceptor molecule derived from horseradish peroxidase. The acceptor was produced from purified peroxidase by the action of a mixture of glycoside hydrolases covalently bound to Sepharose. The membrane preparation containing the transferase was purified approximately 12-fold by aqueous two phase distribution and by discontinuous sucrose density gradient centrifugation.Hydrolysis of the reaction product yielded glucosamine as the only radiolabeled substance. Precipitation of the reaction product by antiserum against peroxidase showed that the label was incorporated into peroxidase. The transferase utilized the acceptor most efficiently when only 12% of the 2-acetamido-2-deoxy-d-glucose was removed from the acceptor. The acceptor lost no accepting capabilities when heated to 100°C for 3 min prior to assay. Trypsin treatment caused a 14% decrease in label incorporated while pronase treatment caused a 93% decrease. 相似文献
77.
James Patrick Cronin Blair E. Tirpak Leah L. Dale Virginia L. Robenski John M. Tirpak Bruce G. Marcot 《The Journal of wildlife management》2021,85(2):324-339
The Perdido Key beach mouse (Peromyscus polionotus trissyllepsis), Choctawhatchee beach mouse (P. p. allophrys), and St. Andrew beach mouse (P. p. peninsularis) are 3 federally endangered subspecies that inhabit coastal dunes of Alabama and Florida, USA. Conservation opportunities for these subspecies are limited and costly. Consequently, well-targeted efforts are required to achieve their downlisting criteria. To aid the development of targeted management scenarios that are designed to achieve downlisting criteria, we developed a Bayesian network model that uses habitat characteristics to predict the probability of beach mouse presence at a 30-m resolution across a portion of the Florida Panhandle. We then designed alternative management scenarios for a variety of habitat conditions for coastal dunes. Finally, we estimated how much area is needed to achieve the established downlisting criterion (i.e., habitat objective) and the amount of effort needed to achieve the habitat objective (i.e., management efficiency). The results suggest that after 7 years of post-storm recolonization, habitat objectives were met for Perdido Key (within its Florida critical habitat) and Choctawhatchee beach mice. The St. Andrew beach mouse required 5.14 km2 of additional critical habitat to be protected and occupied. The St. Andrew beach mouse habitat objective might be achieved by first restoring protected critical habitat to good dune conditions and then protecting or restoring the unprotected critical habitat with the highest predicted probability of beach mouse presence. This scenario provided a 28% increase in management efficiency compared to a scenario that randomly protected or restored undeveloped unprotected critical habitat. In total, when coupled with established downlisting criteria, these quantitative and spatial decision support tools could provide insight into how much habitat is available, how much more is needed, and targeted conservation or restoration efforts that might efficiently achieve habitat objectives. © 2020 The Wildlife Society. 相似文献
78.
Dale L. Rickert Mark Halaki Karen A. Ginn Margaret S. Barrett Bronwen J. Ackermann 《Journal of electromyography and kinesiology》2013,23(6):1261-1268
The physical mechanics of music making is important both in the prevention of injuries and in guiding how music is performed and taught. Electromyography has potential as a resource in understanding the loads involved in instrumental playing; however, only a small number of projects have been undertaken, and little is understood on the muscle activity used during bowing on string instruments. This study aimed to measure the muscle activity at the bowing shoulder of a cellist during cello playing and to establish if fine-wire EMG is useful in understanding muscle recruitment in string players without interfering with normal playing ability. This project used a combination of fine-wire and surface EMG to evaluate the muscular load placed on the right shoulder of a professional cellist whilst playing a set of various bowing exercises. The results indicated that different bowing techniques produced statistically different muscle activity levels, with the supraspinatus muscle in particular maintaining higher mean contraction (20% MVC) during all bowing patterns tested. Fine-wire EMG was useful in measuring shoulder muscle load and did not interfere with normal playing technique of the subject. Overall, the study presents a working protocol from which future studies may be able conduct further research. 相似文献
79.
George L. Trainor Frank W. Hobbs Anthony J. Cocuzza Pat N. Confalone 《Nucleosides, nucleotides & nucleic acids》2013,32(5-6):1175-1176
Abstract A general route for the synthesis of alkynylamino nucleoside triphosphates is described. These nucleosides can be selectively coupled through the alkynylamino group to a variety of reporter groups and used to enzymatically label DNA. 相似文献
80.
Marc A. Jeuland David E. Fuente Semra Ozdemir Maura C. Allaire Dale Whittington 《PloS one》2013,8(10)
The problem of inadequate access to water, sanitation and hygiene (WASH) in less-developed nations has received much attention over the last several decades (most recently in the Millennium Development Goals), largely because diseases associated with such conditions contribute substantially to mortality in poor countries. We present country-level projections for WASH coverage and for WASH-related mortality in developing regions over a long time horizon (1975–2050) and provide dynamic estimates of the economic value of potential reductions in this WASH-related mortality, which go beyond the static results found in previous work. Over the historical period leading up to the present, our analysis shows steady and substantial improvements in WASH coverage and declining mortality rates across many developing regions, namely East Asia and the Pacific, Latin America and the Caribbean, Eastern Europe and the Middle East. The economic value of potential health gains from eliminating mortality attributable to poor water and sanitation has decreased substantially, and in the future will therefore be modest in these regions. Where WASH-related deaths remain high (in parts of South Asia and much of Sub-Saharan Africa), if current trends continue, it will be several decades before economic development and investments in improved water and sanitation will result in the capture of these economic benefits. The fact that health losses will likely remain high in these two regions over the medium term suggests that accelerated efforts are needed to improve access to water and sanitation, though the costs and benefits of such efforts in specific locations should be carefully assessed. 相似文献