scholarly journals Improved homeothermy and hypothermia in African lions during gestation

2016 ◽  
Vol 12 (11) ◽  
pp. 20160645 ◽  
Author(s):  
Paul D. Trethowan ◽  
Tom Hart ◽  
Andrew J. Loveridge ◽  
Anna Haw ◽  
Andrea Fuller ◽  
...  
Keyword(s):  
Parental Care ◽  
Incubation Temperature ◽  
Core Body Temperature ◽  
Thermal Conditions ◽  
Fitness Benefits ◽  
Selection For ◽  
Reproductive Events ◽  
Free Ranging ◽  
Core Body ◽  
African Lions

Mammals use endogenously produced heat to maintain a high and relatively constant core body temperature ( T b ). How they regulate their T b during reproduction might inform us as to what thermal conditions are necessary for optimal development of offspring. However, few studies have measured T b in free-ranging animals for sufficient periods of time to encounter reproductive events. We measured T b continuously in six free-ranging adult female African lions ( Panthera leo ) for approximately 1 year. Lions reduced the 24 h amplitude of T b by about 25% during gestation and decreased mean 24 h T b by 1.3 ± 0.1°C over the course of the gestation, reducing incidences of hyperthermia ( T b > 39.5°C). The observation of improved homeothermy during reproduction may support the parental care model (PCM) for the evolution of endothermy, which postulates that endothermy arose in birds and mammals as a consequence of more general selection for parental care. According to the PCM, endothermy arose because it enabled parents to better control incubation temperature, leading to rapid growth and development of offspring and thus to fitness benefits for the parents. Whether the precision of T b regulation in pregnant lions, and consequently their reproductive success, will be influenced by changing environmental conditions, particularly hotter and drier periods associated with climate change, remains to be determined.

scholarly journals Thermal conditions experienced during differentiation affect metabolic and contractile phenotypes of mouse myotubes

2016 ◽  
Vol 311 (3) ◽  
pp. R457-R465 ◽  
Author(s):  
Alex G. Little ◽  
Frank Seebacher
Keyword(s):  
Body Temperature ◽  
Cold Exposure ◽  
Metabolic Flux ◽  
Core Body Temperature ◽  
Thermal Conditions ◽  
Glycolytic Flux ◽  
Peripheral Tissues ◽  
Atp Production ◽  
Metabolic Role ◽  
Core Body

Central pathways regulate metabolic responses to cold in endotherms to maintain relatively stable internal core body temperatures. However, peripheral muscles routinely experience temperatures lower than core body temperature, so that it would be advantageous for peripheral tissues to respond to temperature changes independently from core body temperature regulation. Early developmental conditions can influence offspring phenotypes, and here we tested whether developing muscle can compensate locally for the effects of cold exposure independently from central regulation. Muscle myotubes originate from undifferentiated myoblasts that are laid down during embryogenesis. We show that in a murine myoblast cell line (C2C12), cold exposure (32°C) increased myoblast metabolic flux compared with 37°C control conditions. Importantly, myotubes that differentiated at 32°C compensated for the thermodynamic effects of low temperature by increasing metabolic rates, ATP production, and glycolytic flux. Myotube responses were also modulated by the temperatures experienced by “parent” myoblasts. Myotubes that differentiated under cold exposure increased activity of the AMP-stimulated protein kinase (AMPK), which may mediate metabolic changes in response cold exposure. Moreover, cold exposure shifted myosin heavy chains from slow to fast, presumably to overcome slower contractile speeds resulting from low temperatures. Adjusting thermal sensitivities locally in peripheral tissues complements central thermoregulation and permits animals to maintain function in cold environments. Muscle also plays a major metabolic role in adults, so that developmental responses to cold are likely to influence energy expenditure later in life.

scholarly journals Clever mothers balance time and effort in parental care: a study on free-ranging dogs

2017 ◽  
Vol 4 (1) ◽  
pp. 160583 ◽  
Author(s):  
Manabi Paul ◽  
Shubhra Sau ◽  
Anjan K. Nandi ◽  
Anindita Bhadra
Keyword(s):  
Parental Care ◽  
Maternal Care ◽  
Group Living ◽  
Lifetime Reproductive Success ◽  
Levels Of Care ◽  
Future Reproduction ◽  
Fitness Benefits ◽  
Time And Energy ◽  
Free Ranging ◽  
Active Care

Mammalian offspring require parental care, at least in the form of nursing during their early development. While mothers need to invest considerable time and energy in ensuring the survival of their current offspring, they also need to optimize their investment in one batch of offspring in order to ensure future reproduction and hence lifetime reproductive success. Free-ranging dogs live in small social groups, mate promiscuously and lack the cooperative breeding biology of other group-living canids. They face high early-life mortality, which in turn reduces fitness benefits of the mother from a batch of pups. We carried out a field-based study on free-ranging dogs in India to understand the nature of maternal care. Our analysis reveals that mothers reduce investment in energy-intensive active care and increase passive care as the pups grow older, thereby keeping overall levels of care more or less constant over pup age. Using the patterns of mother–pup interactions, we define the different phases of maternal care behaviour.

Metabolic correlates of selection for swim stress-induced analgesia in laboratory mice

1997 ◽  
Vol 273 (1) ◽  
pp. R337-R343 ◽  
Author(s):  
M. Konarzewski ◽  
B. Sadowski ◽  
I. Jozwik
Keyword(s):  
Metabolic Rate ◽  
Core Body Temperature ◽  
Metabolic Rates ◽  
Laboratory Mice ◽  
Swim Stress ◽  
Upper Limits ◽  
Maximal Metabolic Rate ◽  
Selection For ◽  
Core Body ◽  
Selection Agent

The upper limits of metabolic rates and the links between maximal and resting metabolic rates in vertebrates have recently received a lot of attention, mainly due to their possible relationship to the evolution of endothermy. We measured peak metabolic rates during 3 min swimming in 20 degrees C water (Vo2swim), maximal metabolic rate (Vo2max) in -2.5 degrees C Helox, and basal metabolic rate (BMR) in two lines of mice selected for high (HA) and low (LA) swim stress-induced analgesia (SSIA). We found that exercise combined with heat loss used for producing SSIA also acted as a selection agent, resulting in a 15% HA/LA line difference in Vo2swim. Core body temperature of HA mice (characterized by lower Vo2swim) was also on average 3.2 degrees C lower than that of LA mice. Furthermore, Vo2max of HA mice was lower than that of LA mice by 8% and accompanied by larger hypothermia. Thus mice with exceptionally high (or low) Vo2max tended to have exceptionally high (or low) Vo2swim, resulting in a positive correlation between Vo2swim and Vo2max. All these suggest that selection for SSIA produced genetically correlated responses in both Vo2swim and Vo2max. However, we did not observe HA/LA differences in BMR. Hence, changes in resting and maximum metabolic rates are not necessarily correlated. We hypothesize that the lack of such a correlation was partially due to the modulation of metabolic responses by SSIA.

Core body temperature changes after sauna exposition in healthy subjects

2012 ◽  
Vol 26 (2) ◽  
Author(s):  
Joanna Pawlak ◽  
Paweł Zalewski ◽  
Jacek J. Klawe ◽  
Monika Zawadka ◽  
Anna Bitner ◽  
...  
Keyword(s):  
Body Temperature ◽  
Healthy Subjects ◽  
Core Body Temperature ◽  
Temperature Changes ◽  
Core Body

Nonphotic entrainment of the human circadian pacemaker

1998 ◽  
Vol 274 (4) ◽  
pp. R991-R996 ◽  
Author(s):  
Elizabeth B. Klerman ◽  
David W. Rimmer ◽  
Derk-Jan Dijk ◽  
Richard E. Kronauer ◽  
Joseph F. Rizzo ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Light Exposure ◽  
Core Body Temperature ◽  
Biological Clock ◽  
Bright Light ◽  
Circadian Pacemaker ◽  
Temperature Rhythms ◽  
Blind Individuals ◽  
Nonphotic Entrainment ◽  
Core Body

In organisms as diverse as single-celled algae and humans, light is the primary stimulus mediating entrainment of the circadian biological clock. Reports that some totally blind individuals appear entrained to the 24-h day have suggested that nonphotic stimuli may also be effective circadian synchronizers in humans, although the nonphotic stimuli are probably comparatively weak synchronizers, because the circadian rhythms of many totally blind individuals “free run” even when they maintain a 24-h activity-rest schedule. To investigate entrainment by nonphotic synchronizers, we studied the endogenous circadian melatonin and core body temperature rhythms of 15 totally blind subjects who lacked conscious light perception and exhibited no suppression of plasma melatonin in response to ocular bright-light exposure. Nine of these fifteen blind individuals were able to maintain synchronization to the 24-h day, albeit often at an atypical phase angle of entrainment. Nonphotic stimuli also synchronized the endogenous circadian rhythms of a totally blind individual to a non-24-h schedule while living in constant near darkness. We conclude that nonphotic stimuli can entrain the human circadian pacemaker in some individuals lacking ocular circadian photoreception.

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