Thermal biology and locomotor performance in Phymaturus calcogaster: are Patagonian lizards vulnerable to climate change?

Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature. In particular, niche-specialist lizards are dependent on their physiological plasticity to adjust to changing environmental conditions. Lizards of the genus Phymaturus are viviparous, mainly herbivorous, and inhabit only rock promontories in the steppe environments of Patagonia and the Andes. Herein, we examine the vulnerability of the southernmost Phymaturus species to global warming: the endemic Phymaturus calcogaster, which lives in a mesic environment in eastern Patagonia. We studied body temperatures in the field (T_b), preferred body temperatures in a thermogradient (T_pref), the operative (T_e) and environmental temperatures, and the dependence of running performance on body temperature. P. calcogaster had a mean T_b (27.04°C) and a mean T_e (31.15°C) both lower than their preferred temperature (T_pref = 36.61°C) and the optimal temperature for running performance (T_o = 37.13°C). Lizard activity seems to be restraint during the early afternoon due high environmental temperatures. However, both, the high safety margin and warming tolerance suggest that the expected increase in environmental temperatures due to global warming (IPCC report in 2018) would not threaten, but indeed enhance locomotor performance in this population.     

Body temperature,activity patterns and hunting in free‐living cheetah: biologging reveals new insights

As one of the few felids that is predominantly diurnal, cheetahs (Acinonyx jubatus) can be exposed to high heat loads in their natural habitat. Little is known about long‐term patterns of body temperature and activity (including hunting) in cheetahs because long‐term concurrent measurements of body temperature and activity have never been reported for cheetahs, or, indeed, for any free‐living felid. We report here body temperature and locomotor activity measured with implanted data loggers over 7 months in 5 free‐living cheetahs in Namibia. Air temperature ranged from a maximum of 39 °C in summer to ?2 °C in winter. Cheetahs had higher (～0.4 °C) maximum 24‐h body temperatures, later acrophase (～1 h), with larger fluctuations in the range of the 24‐h body temperature rhythm (approximately 0.4 °C) during a hot‐dry period than during a cool‐dry period, but maintained homeothermy irrespective of the climatic conditions. As ambient temperatures increased, the cheetahs shifted from a diurnal to a crepuscular activity pattern, with reduced activity between 900 and 1500 hours and increased nocturnal activity. The timing of hunts followed the general pattern of activity; the cheetahs hunted when they were on the move. Cheetahs hunted if an opportunity presented itself; on occasion they hunted in the midday heat or in total darkness (new moon). Biologging revealed insights into cheetah biology that are not accessible by traditional observer‐based techniques.     

Study on The Isozyme of Wild Yak

We have adopted PAGE method to isolate lactic dehydrogenase(LDH)and α-amylase(α-Am)from wild yak's serum and measure the physical-chemical properties of the two components respectively. The results showed that the yak LDH isozyme distributed into five bands. The sequence according to their activity reads as LDH1 ＞ LDH2＞ LDH3 ＞ LDH4 ＞ LDH5. The subunit B is relatively occupied a dominant position. It got a wide operating pH range, high thermal stability,well denature resistance and a fairly large adaptability threshold on the physical-chemical change of surrounding environment. α-Am isozyme distributed into seven bands and also got a wide operating pH range. α-Am isozyme is high sensitivity to environmental temperature.     

Physiological responses of dietary tryptophan fed Labeo rohita to temperature and salinity stress

Two experiments were conducted to elucidate the possible effects of dietary L‐tryptophan (TRP) in Labeo rohita based on growth performance and physio‐biochemical responses. In the experiment I, a 60‐day feeding trial was carried out to elucidate the effects of dietary TRP enrichment on growth performance and physio‐biochemical responses. In the experiment II, the TRP pre‐fed L. rohita, from experiment I, was exposed to temperature and salinity stress to evaluate stress‐mitigating efficacy of TRP. In L. rohita, dietary supplementation of TRP showed significant effect on weight gain percentage and feed conversion ratio but not on blood glucose. A significant increase in RNA content and RNA/DNA ratio upon TRP supplementation was observed and was positively correlated with growth performance. The results of experiment II indicated that weight gain percentage, serum T3 and T4 levels were significantly reduced in groups that were exposed to temperature and salinity stress and fed diets without TRP supplementation. However, dietary supplementation of TRP significantly augmented weight gain percentage in stress‐exposed groups. Tryptophan supplementation helped in bringing back T3 and T4 levels comparable with control. A significant increase in superoxide dismutase, catalase, Adenosine triphosphatase, blood glucose and serum cortisol was observed in temperature‐ and salinity‐exposed groups fed without TRP‐supplemented diets. However, TRP supplementation was found to be effective in restoring the above parameters. The results of these experiments suggest that dietary TRP supplementation augments growth, lowers energy demand and helps in mitigating thermal and salinity stress in L. rohita.     

Does the cellphone radio-frequency electromagnetic radiation during ringing or talking modes induce locomotor disturbance in Drosophila melanogaster?

Debate regarding the biological effect of electromagnetic radiation has been recently raised. The effects of this radiation on locomotor activity are not well known. Hence, in this study, we used Drosophila melanogaster as a model organism to investigate the possible effects of short-term exposure to ringing or talking cellphone modes on locomotor activity. Interestingly, an hour exposure to the cellphone ringing mode did not significantly affect the fly movement speed in the negative geotaxis assay. However, the flies exposed to sending or sending–receiving ringing modes showed disturbed movement paths compared with control flies. To verify these results, third-instar larvae were tested using a crawling assay. The larvae exposed to emissions of 1 h sending-rings tended to crawl in short, random and scattered paths, whereas control larvae crawled parallel to the wall of the petri dish. On the other hand, exposure to the cellphone talking mode induced significant reduction in the movement speed of adult Drosophila. The speed of flies exposed to sending mode showed a negative regression with the time of exposure. The flies exposed to receiving-talk mode were significantly slower than the controls at all tested time intervals. Furthermore, the flies exposed to 1 or 2 h sending-talks exhibited irritated zigzag locomotor paths and hyperactivity. The results suggest that prolonged exposure to signalling cellphone electromagnetic radiation may exert locomotor disorders as evident by significant alterations in the neuro-behavioural events related to locomotor equilibrium of D. melanogaster.     

Resting metabolic rates increase with elevation in a mountain‐dwelling lizard

Individuals that inhabit broad elevational ranges may experience unique environmental challenges. Because temperature decreases with increased elevation, the ectotherms living at high elevations have to manage limited activity time and high thermoregulatory effort. The resting metabolic rate (RMR) of a postabsorptive animal is related to its total energy requirements as well as many other fitness traits. Mesquite lizards (Sceloporus grammicus) living on La Malinche Volcano, Mexico, inhabit a wide elevational range with some populations apparently thriving above the tree line. We measured the RMR of lizards from different elevations (i.e., 2,600, 3,200, and 4,100 m) at four ecologically relevant temperatures (i.e., 15, 25, 30, and 35 °C) and found that RMR of mesquite lizards increased with temperature and body mass. More importantly, lizards from the high‐elevation population had mass specific RMR that was higher at all temperatures. While the higher RMRs of high‐elevation populations imply higher metabolic costs at a given temperature these lizards were also smaller. Both of these traits may allow these high elevation populations to thrive in the face of the thermal challenges imposed by their environment.     

Anaerobic metabolism and thermal tolerance: The importance of opine pathways on survival of a gastropod after cardiac dysfunction

Organisms on rocky shores are frequently exposed to high temperatures, which cause impairment of cardiac function and retard cellular oxygen delivery. However, some gastropods can survive at several degrees Celsius higher than their Arrhenius break temperature of cardiac function (ABT), indicating the importance of anaerobic metabolism for their thermal tolerance. We measured the global molecular responses to heat stress in limpet Cellana toreuma using 454 GS‐FLX to investigate the variations of genes involved in anaerobic metabolism at high temperatures. Next, the gene expression levels of 4 anaerobic enzymes and activity of alanopine dehydrogenase (AlDH), which is involved in opine pathway, were measured in response to elevated temperature. A total of 19 heat shock proteins (HSPs) were determined using real‐time PCR at different temperatures. At high temperatures, the extensive upregulation of HSP genes was an effective but energetically expensive form of protection to prevent thermal damage. The upregulation of hypoxia‐inducible factor 1 alpha mRNA indicated the condition of cellular hypoxia and the high gene expression and enzyme activity of AlDH suggested that opine pathway was the main anaerobic pathway. These results implied that anaerobic metabolism was enhanced to provide energy in the face of thermal stress. Our findings highlight the ecological significance of the anaerobic metabolism of gastropods to thermal adaptation. For predicting the ecological impact of global warming on the distribution of gastropods, the role of anaerobic pathways should be evaluated.     

Would behavioral thermoregulation enable pregnant viviparous tropical lizards to cope with a warmer world?

Sceloporus lizards depend on external heat to achieve their preferred temperature (T_sel) for performing physiological processes. Evidence both in the field and laboratory indicates that pregnant females of this Genus select body temperatures (T_b) lower than 34 °C as higher temperatures may be lethal to embryos. Therefore, thermoregulation is crucial for successful embryo development. Given the increase in global air temperature, it is expected that the first compensatory response of species that inhabit tropical climates will be behavioral thermoregulation. We tested whether viviparous Sceloporus formosus group lizards in the wild exhibited differences in thermoregulatory behavior to achieve the known T_sel for developing embryos regardless of local thermal conditions. We quantified field active body temperature, thermoregulatory behavior mechanisms (time of sighting, microhabitat used and basking time) and available microhabitat thermal conditions (i.e. operative temperature) for 10 lizard species during gestation, distributed along an altitudinal gradient. We applied both conventional and phylogenic analyses to explore whether T_b or behavioral thermoregulation could be regulated in response to different thermal conditions. These species showed no significant differences in field T_b during gestation regardless of local thermal conditions. In contrast, they exhibited significant differences in their behavioral thermoregulation associated with local environmental conditions. Based on these observations, the differences in thermoregulatory behavior identified are interpreted as compensatory adjustments to local thermal conditions. We conclude that these species may deal with higher temperatures predicted for the tropics by modulating their thermoregulatory behavior.     

Impact of stocking density on broiler growth performance,meat characteristics,behavioural components and indicators of physiological and oxidative stress

1. The study was designed to assess the impact of stocking density (6 and 13 birds/m² equivalent to 12·6 or 27·2?kg/m², respectively) on growth performance, meat quality, behaviour, and indicators of physiological and oxidative stress as measures of bird welfare.

2. The higher stocking density negatively affected final body weight and feed intake but not cumulative feed conversion rate. Muscle colour traits, pH₂₄, cooking loss and shear values were not affected. Birds reared at the lower density showed higher intramuscular fat, liver weight, liver NADP-isocitrate and NADP-malate dehydrogenase activity.

3. Higher stocking density was associated with decreased locomotor activity and increased physiological (H:L ratio and bursa weight) and oxidative (glutathione concentrations and reduced:oxidised glutathione ratios) stress indicators.

4. The results show that stocking density did not significantly affect broiler meat quality characteristics but higher density decreased growth performance, increased physiological and oxidative stress levels and decreased locomotor activity.     

Temperature and salinity tolerance of adult hermit crabs,Diogenes brevirostris,Stimpson (Crustacea: Decapoda: Anomura)

Diogenes brevirostris was found to be tolerant to low salinities (0,5 - 4,0 %) at a wide range of temperatures (12 to 27°C). Tolerance to temperature and salinity were inversely related. At low salinities (0,5 and 1,0 %) the rate of mortality increased with temperature throughout the range, whereas at higher salinities (1,5 and 4,0 0/00) temperature had no effect on mortality. These results are discussed in relation to the distribution of D. brevirostris in estuaries. It appears that temperature and salinity tolerance are not solely responsible for limiting distribution of these crabs to estuary mouths.     

多年生黑麦草对干旱-低温交叉适应的生理响应

草坪草在冬季的时候常常面临着干旱和低温的双重胁迫,严重影响着春季返青时草坪草的质量。为了探讨多年生黑麦草的干旱-低温胁迫交叉适应的生理机制,以多年生黑麦草“爱神特(Accent)”为植物材料,设置3个水分梯度,土壤相对含水量分别为30%(重度胁迫)、60%(中度胁迫)、100%(良好浇水)。处理5 d后在人工气候箱中进行低温处理(2℃)15 d。低温胁迫使多年生黑麦草的叶片相对含水量、叶绿素含量显著降低,电解质渗漏、脯氨酸、可溶性总糖、抗氧化酶的含量增加。3种水分处理条件下,经过中度干旱处理后的多年生黑麦草的叶片相对含水量、叶绿素含量的降低幅度减小,但脯氨酸、可溶性糖、抗氧化酶的含量增加显著。实验结果表明多年生黑麦草对干旱-低温胁迫具有交叉适应能力。适当地进行干旱处理有利于提高多年生黑麦草对低温胁迫的适应能力。但值得注意的是,严重的干旱处理会造成过度伤害,致使植株更快死亡。     

Embryonic and post‐embryonic responses to high‐elevation hypoxia in a low‐elevation lizard

Low‐elevation species can migrate toward higher elevations to survive in a warming world. However, animals’ responses to hypoxia when migrating to high elevations have rarely been addressed. To identify the response of low‐elevation lizards to high‐elevation hypoxia, we collected field body temperatures (T_fb) and operative temperatures (T_e) of lizards (Eremias argus) from a low‐elevation population (1036 m) and a high‐elevation population (2036 m), and then determined adult thermal physiology, embryonic development, and hatchling phenotypes after acclimating low‐elevation lizards and incubating their eggs in conditions mimicking the low‐elevation oxygen condition (18.5% O₂) and high‐elevation oxygen (hypoxic) condition (16.5% O₂). Our study revealed that T_fb and T_e were higher for the low‐elevation population compared to the high‐elevation population. We also found adults from low elevation acclimated to hypoxia preferred lower body temperatures, but did not show changes in locomotor performance or growth. In addition, hypoxia did not affect embryonic development (hatching time and success) or hatchling phenotypes (body size and locomotor performance). These results suggest that adult lizards from low elevations can respond to hypoxia‐induced stress when migrating to high elevations by behaviorally thermoregulating to lower body temperatures in order to sustain normal functions. Similarly, low‐elevation embryos can develop normally (with unchanged hatching success and offspring phenotypes) under the high‐elevation hypoxic condition. This study highlights that low‐elevation populations of a species that inhabits a range of elevations can buffer the impact of high‐elevation hypoxic conditions to some degree and thus attain similar fitness to the source population.     

Effect of feed rate and drill speed on temperatures in equine cortical bone.

OBJECTIVE: To examine the amount of heat generated in equine cortical bone by a 6.2-mm drill, using low- and high-speed and controlled feed rate drilling. SAMPLE POPULATION: 10 metacarpal bones harvested from five 2-year-old draft-type horses. PROCEDURE: Drilling on metacarpal bones was done using a machine shop mill with which the feed rate and drill speed could be precisely controlled. Bones were drilled, using 6 combinations of feed rate (1, 2, and 3 mm advance/s) and drill speed (317 and 1,242 revolutions/min [rpm], with maximal temperatures recorded by thermocouples placed 1, 1.5, and 2 mm from the drill. Maximal temperatures were evaluated for the effect of feed rate, drill speed, cortical thickness, and distance from the drill, using linear regression analysis. RESULTS: Increasing feed rate from 1 to 2 and from 2 to 3 mm/s significantly decreased mean maximal temperature. Increasing drill speed from 317 to 1242 rpm significantly increased mean maximal temperature. Increasing cortical thickness significantly increased mean maximal temperature, and increasing the distance from the drill hole significantly decreased mean maximal temperatures. CONCLUSIONS: On the basis of our results, we recommend using low drill speeds while applying sufficient axial force to advance the drill as rapidly as possible through the bone. CLINICAL RELEVANCE: Results of using this in vitro model suggest that temperatures at the drill-bone interface may be sufficiently high to result in significant thermal necrosis when drilling equine cortical bone.     

猪带绦虫囊尾蚴体内发育过程中囊壁生化指标的变化

对猪体内发育30，40，60，80，95日猪囊尾蚴囊壁的已糖激酶（HK），丙酮酸激酶（PK），乳酸脱氢酶（LDH），苹果酸脱氢酶（MDH），葡萄糖－6－磷酸脱氢酶（G6PDH）活性和葡萄糖（GLc)，乳酸（LAC）含量进行测定，结果表明，HK，PK，MDH活性和GLc含量在60，80，95日高于或显著高于30，40日（P＞0．05，P＜0．05），说明随虫体的生长发育糖代谢逐渐增加。     

Locomotor activity, core body temperature, and circadian rhythms in mice selected for high or low heat loss

Daily locomotor activity, core body temperature, and their circadian rhythms were measured in lines of mice selected for high (MH) or low (ML) heat loss and unselected controls (MC). Lines were created by selecting for 16 generations in each of three replicates. Collection of locomotor activity and core temperature data spanned Generations 20 and 21 for a total of 352 mice. Physical activity and core body temperature data were accumulated using implanted transmitters and continuous automated collection. Measurement for each animal was for 3 d. Activity was recorded for each half hour and then averaged for the day; temperature was averaged daily; circadian rhythm was expressed in 12-h (light vs dark) or 6-h periods as well as by fitting cyclic models. Activity means were transformed to log base 2 to lessen heterogeneity of variance within lines. Heat loss for a 15-h period beginning at 1630 and feed intake for 7 d were measured on 74 additional mice in order to estimate the relationship between locomotor activity and heat loss or feed intake. Selection lines were different (P < 0.01) for both locomotor activity and core body temperature. Differences were due to selection (MH-ML, P < 0.01), and there was no evidence of asymmetry of response (P > 0.38). Retransformed from log base 2 to the scale of measurement, mean activity counts were 308, 210, and 150 for MH, MC, and ML, respectively. Mean core temperatures were 37.2, 36.9, and 36.7 degrees C for MH, MC, and ML (P < 0.01), respectively. Females had greater physical activity (P < 0.01) and body temperature (P < 0.01) than males. There was no evidence of a sex x selection criterion interaction for either activity or temperature (P > 0.20). Overall phenotypic correlation between body temperature and log base 2 activity was 0.43 (P < 0.01). Periods during the day were different for both 12- and 6-h analyses (P < 0.01), but there were no period x selection criterion interactions (P > 0.1) for physical activity or body temperature. More sensitive cyclic models revealed significant (P < 0.01) 24-, 12-, 8-, and 6-h cycles that differed (P < 0.01) among lines. Estimated differences between MH and ML mice in feed intake and heat loss due to locomotor activity were 36 and 11.5%, respectively. Variation in activity thus contributed to variation in feed intake.     

LDH and CK isoenzyme patterns in the blood plasma of horses with elevated CK, LDH and AST activities

The distribution of LDH and CK isoenzymes in blood plasma of ten clinically sound Thoroughbreds with reasonable performance and without elevated clinico-chemical blood variables (reference group) was compared with 57 Thoroughbreds, which had histories of mild locomotor disturbances and/or poor performance and had elevated CK, LDH and/or AST activities (trial group). The trial group was subdivided according to the number of altered blood variables and in the groups with two as well as three altered blood variables also according to the extent of alteration of the total CK activity. The pattern of LDH and CK isoenzyme distribution in the blood plasma of the reference group was the following: 22% LDH1, 36% LDH2, 34% LDH3, 6% LDH4 and 2% LDH5 as well as 75% CK1 and 15% CK2. The remaining 10% of the plasma electropherogram could not be alloted to any one of the two CK bands. All trial groups built showed a similar pattern of changes in their isoenzyme distribution independent on kind and combination of altered enzyme activities. The shares of CK1, LDH4 and LDH5 were significantly increased whilst the shares of CK2, LDH1 and LDH2 decreased. A multiple analysis of variance demonstrated that only increased total CK activities had a pronounced effect on distribution of LDH and CK isoenzyme patterns in the trial group (p less than 0.01 for LDH2, LDH3, LDH4, CK1 and p less than 0.05 for CK2). The conclusion of the study was that the altered distribution pattern of LDH and CK isoenzymes of the trial group signalized an increased skeletal muscle membrane leakage.     

Changes in activities of enzymes related to energy metabolism in canine lymphoma cells

Alterations in the activities of enzymes related to energy metabolism in canine lymphoma cells were investigated. Cytosolic pyruvate kinase (PK) and mitochondrial malate dehydrogenase (MDH) activities in lymphoma cells were significantly higher than those in lymphocytes obtained from lymph nodes of healthy dogs, whereas cytosolic lactate dehydrogenase (LDH) activity was significantly lower in lymphoma cells. The cytosolic M/L ratio (MDH activity/LDH activity), which is considered to be a good indicator of energy metabolism related to glucose utilization in animal tissues, was significantly higher in lymphoma cells than in the normal lymphocytes.     

Pharmacokinetics of butorphanol and evaluation of physiologic and behavioral effects after intravenous and intramuscular administration to neonatal foals

Background: Despite frequent clinical use, information about the pharmacokinetics (PK), clinical effects, and safety of butorphanol in foals is not available. Objectives: The purpose of this study was to determine the PK of butorphanol in neonatal foals after IV and IM administration; to determine whether administration of butorphanol results in physiologic or behavioral changes in neonatal foals; and to describe adverse effects associated with its use in neonatal foals. Animals: Six healthy mixed breed pony foals between 3 and 12 days of age were used. Methods: In a 3‐way crossover design, foals received butorphanol (IV and IM, at 0.05 mg/kg) and IV saline (control group). Butorphanol concentrations were determined by high‐performance liquid chromatography and analyzed using a noncompartmental PK model. Physiologic data were obtained at specified intervals after drug administration. Pedometers were used to evaluate locomotor activity. Behavioral data were obtained using a 2‐hour real‐time video recording. Results: The terminal half‐life of butorphanol was 2.1 hours and C₀ was 33.2 ± 12.1 ng/mL after IV injection. For IM injection, C_max and T_max were 20.1 ± 3.5 ng/mL and 5.9 ± 2.1 minutes, respectively. Bioavailability was 66.1 ± 11.9%. There were minimal effects on vital signs. Foals that received butorphanol spent significantly more time nursing than control foals and appeared sedated. Conclusions and Clinical Importance: The disposition of butorphanol in neonatal foals differs from that in adult horses. The main behavioral effects after butorphanol administration to neonatal foals were sedation and increased feeding behavior.     

Biokinematics under Competitive Racing Conditions in Young Standardbred Trotters: A Preliminary Report

With the aim of evaluating equine performance in competitive trotter horses under normal racing conditions data of stride length, stride frequency and mean horses speed were obtained from 50, 2-year-old Italian winner fillies during the racing and the sprint laps of competition. The enhancement of speed in the sprint lap was obtained by increasing both stride length and stride frequency. Stride frequency for the racing and the sprint laps were (mean ± SD) 133.63 ± 3.93 and 138.97 ± 6.62 strides per minute, respectively and Stride length for the racing and the sprint laps were 7.17 ± 0.17 and 7.30 ± 0.11 m, respectively; mean speed was 48.18 ± 1.09 km/hr. The usefulness of the kinematic assessments is discussed as is its potential reference for future indicators of performance.     

Ability to utilize lactate and related enzymes of a ruminal bacterium, Selenomonas ruminantium

The ability of a nitrate‐reducing and nitrite‐reducing strain of Selenomonas ruminantium ssp. lactilytica (TH1) to utilize lactate was examined at the cell and enzyme levels. The TH1 strain was found to possess NAD‐independent D‐lactate dehydrogenase (iD‐LDH), with little or no lactate racemase or L‐lactate dehydrogenase, implying that TH1 virtually utilizes only the D‐form of lactate. Therefore, the introduction of lactate racemase to TH1 may enhance its ability to utilize lactate in the rumen where both D‐lactate and L‐lactate are produced. Because lactate utilization by Megasphaera elsdenii in the rumen may increase methanogenesis, it is desirable to increase lactate utilization by S. ruminantium, which may decrease methanogenesis. However, the specific activity of iD‐LDH, which represents the amount of enzyme per cell, in TH1 was approximately threefold lower than M. elsdenii. Properties of iD‐LDH, such as optimal pH and temperature, affinity for D‐lactate, and effect of metal ions, did not differ greatly between TH1 and M. elsdenii. The specific activity of iD‐LDH in TH1 increased as the D‐lactate concentration in the medium increased, suggesting that iD‐LDH synthesis is regulated in response to D‐lactate. On the contrary, no iD‐LDH activity was detected when TH1 was grown in the presence of glucose, even when D‐lactate was present. This result suggests that iD‐LDH synthesis is strongly suppressed by glucose. In order to improve the ability of S. ruminantium to utilize lactate and reduce nitrate and nitrite, it is important to enhance iD‐LDH synthesis in addition to the introduction of lactate racemase.