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Different Adaptations (different + adaptation)
Selected AbstractsDifferent adaptations of alpha-actinin isoforms to exercise training in rat skeletal musclesACTA PHYSIOLOGICA, Issue 3 2009Y. Ogura Abstract Aim:, Alpha (,)-actinins are located in the skeletal muscle Z-line and form actin,actin cross-links. Mammalian skeletal muscle has two isoforms: ,-actinin-2 and ,-actinin-3. However, the response of ,-actinin to exercise training is little understood. Therefore, the current study examined the effects of exercise training on the expression level of two ,-actinin isoforms in skeletal muscles. Methods:, Twelve male Wistar rats were assigned randomly to a control (C; n = 6) or exercise training (T; n = 6) group. After T animals were trained on an animal treadmill for 9 weeks, ,-actinin-2 and ,-actinin-3 levels in the plantaris, white and red gastrocnemius muscles were analysed. In addition, changes in the myosin heavy chain (MyHC) composition were assessed, and muscle bioenergetic enzyme activities were measured. Results:, Results show that exercise training increased ,-actinin-2 expression levels in all muscles (P < 0.05). However, no significant difference was found in ,-actinin-3 expression levels between C and T animals. Subsequent MyHC analyses of all muscle showed an MyHC shift with direction from IIb to IIa. Furthermore, enzymatic analysis revealed that exercise training improved enzyme activities related to aerobic metabolism. Conclusion:, The results of this study demonstrate that exercise training alters the expression level of ,-actinin at the isoform level. Moreover, the increase in expression levels of ,-actinin-2 is apparently related to alteration of skeletal muscle: its aerobic capacity is improved. [source] Arm and leg substrate utilization and muscle adaptation after prolonged low-intensity trainingACTA PHYSIOLOGICA, Issue 4 2010J. W. Helge Abstract This review will focus on current data where substrate metabolism in arm and leg muscle is investigated and discuss the presence of higher carbohydrate oxidation and lactate release observed during arm compared with leg exercise. Furthermore, a basis for a possible difference in substrate partitioning between endogenous and exogenous substrate during arm and leg exercise will be debated. Moreover the review will probe if differences between arm and leg muscle are merely a result of different training status rather than a qualitative difference in limb substrate regulation. Along this line the review will address the available studies on low-intensity training performed separately with arm or legs or as whole-body training to evaluate if this leads to different adaptations in arm and leg muscle resulting in different substrate utilization patterns during separate arm or leg exercise at comparable workloads. Finally, the influence and capacity of low-intensity training to influence metabolic fitness in the face of a limited effect on aerobic fitness will be challenged. [source] DEFINED ORDER OF EVOLUTIONARY ADAPTATIONS: EXPERIMENTAL EVIDENCEEVOLUTION, Issue 7 2008Erez Oxman Organisms often adapt to new conditions by means of beneficial mutations that become fixed in the population. Often, full adaptation requires several different mutations in the same cell, each of which may affect a different aspect of the behavior. Can one predict order in which these mutations become fixed? To address this, we experimentally studied evolution of Escherichia coli in a growth medium in which the effects of different adaptations can be easily classified as affecting growth rate or the lag-phase duration. We find that adaptations are fixed in a defined and reproducible order: first reduction of lag phase, and then an increase of the exponential growth rate. A population genetics theory explains this order, and suggests growth conditions in which the order of adaptations is reversed. We experimentally find this order reversal under the predicted conditions. This study supports a view in which the evolutionary path to adaptation in a new environment can be captured by theory and experiment. [source] Host preference and performance of lichenivorous Eilema spp. larvae in relation to lichen secondary metabolitesJOURNAL OF ANIMAL ECOLOGY, Issue 3 2003Heikki Pöykkö Summary 1We compared the larval host preference of four lichenivorous Eilema (Lepidoptera, Arctiidae) species on four common epiphytic lichen species including Hypogymnia physodes, Melanelia exasperata, Vulpicida pinastri and Xanthoria parietina. Survival and growth of larvae on different species were monitored and correlation to qualitative and quantitative variation in lichen secondary compounds was analysed. 2All moth species preferred M. exasperata, which does not contain polyphenolic substances, over other lichens, but also foraged on other lichens in the food preference experiment. All larvae reared on V. pinastri and H. physodes died during the growth and survival experiment. Survival of larvae on X. parietina and M. exasperata were equal. Larvae grew faster and and bigger on M. exasperata than on other lichens. 3Consumption and utilization measurements also revealed that M. exasperata was of the highest quality, although the relative consumption rate was highest on X. parietina. Our results indicate that different secondary chemicals have different effect against lichenivores or that larvae are either well adapted to certain chemicals or that these chemicals may have other roles than antiherbivore function for lichens. 4It is suggested that lichenivorous lepidopteran species may have different adaptations, such as dietary mixing to receive nutrients in optimal proportions or compensatory feeding ability to ensure the maximal growth efficiency on a suboptimal host. [source] | ||||||||||