The effects of ambient temperature and thermoregulation on locomotor performance of newborn Guide toad-headed lizards (Phrynocephalus putjatia)

The effect of thermal environments during embryonic development as a proximate source of variation in the fitness of offspring has been examined in a wide variety of taxa, and reptiles have been proved to be excellent mode systems for research in this field. Here, we describe a study revealing the effects of ambient temperature and thermoregulation on locomotor performance of newborn ovoviviparous lizards. A 2 (background temperatures set at 18 °C or 22 °C) × 2 (allowing thermoregulation for 14 h or 10 h daily) factorial design experiment was carried out to examine the effects of ambient temperature and thermoregulation on the locomotor performance of newborn Guide toad-headed lizards (Phrynocephalus putjatia; Agamidae). Gravid females were collected in May 2010 from a population in Guide, Qinghai, northwestern China, and were transported to our laboratory in Hangzhou. Ten to fifteen females were housed together in 1200 mm × 600 mm × 700 mm (length × width × height) communal cages, which were placed in AAPS (artificial atmospheric phenomena simulator) rooms, and contained a substrate of sand (～400 mm depth), with rocks and pieces of clay tiles provided as shelter and basking sites. One light bulb (200 W) was suspended above one end of the cage to create a thermal gradient ranging from room temperature to 60 °C for 14 h or 10 h daily, and overnight temperatures followed AAPS temperatures (18 °C or 22 °C). Food (mealworms and house crickets) dusted with multivitamins and minerals and water were provided daily. Cages were checked twice daily for neonates after the first female gave birth, and neonates were immediately collected and weighed after birth.Twenty neonates from single litters of each testament were measured at birth for locomotor performance. All running trials were conducted at a body temperature of 30 °C, which was achieved by placing the newborns in an incubator at 30 °C for 30 min prior to testing. Locomotor performance was assessed by chasing the neonates along a 2-m-long racetrack, which was placed in a room at constant 30 °C, with one side of the racetrack transparent, allowing videoing with a Panasonic NV-DS77 digital video camera. The tapes were later examined with a computer using MGI VideoWave III software for PC (MGI Software Co., Toronto, Canada) for sprint speed in the fastest 250-mm interval and the maximal length. Each individual was measured five times after birth, at 15-day intervals, until 60 days.We found that locomotor performance of neonates was affected by thermoregulating opportunity, but not by background temperature. Neonates produced by females thermoregulated for 14 h daily performed better (both sprint speed and the maximal length) in the racetrack than those produced by females thermoregulated for 10 h daily. However, the interaction between background temperature and thermoregulating opportunity was not a significant source of variation in locomotor performance. Moreover, sprint speed was positively correlated to the maximal length in newborn P. putjatia. In summary, locomotor performance is a highly fitness-related trait, and this study implies that viviparity allows female P. putjatia to provide optimal temperatures for embryo development through thermoregulation, thereby producing well-performed offspring.     

Effect of the desiccation tolerance and cryopreservation methods on the viability of Citrus limon L. Burm cv. Eureka seeds

Cryopreservation of the germplasm for long-term periods is of great importance to maintain the genetic resource. Argentina is one of the world's highest lemon producing country. The performance of different cooling/warming rates in the cryopreservation method of Citrus limon L. Burm cv. Eureka seeds and their influence on the interval of optimal moisture content in the desiccation stage were analyzed. Water sorption isotherm was determined and modeled using D'Arcy & Watt equation; it provided important information concerning the amounts of water associated to strong, weak and multimolecular binding sites along the sorption isotherm. Seeds tolerated a wide range of desiccation conditions (0.1<a_w<0.85) showing a high viability (>80%), however desiccation to 0.0526 g H₂O g⁻¹ d.b. (a_w = 0.0901) produced a significant loss of viability. Differential Scanning Calorimetry was used to identify the thermal transitions of lipids and water in the seed; enthalpies were used to calculate the unfrozen water fraction (0.19 g H₂O g⁻¹ d.b. corresponding to a_w = 0.64). Two cooling/warming rates were tested on desiccated seeds (0.11<a_w<0.85): i) 200 °C min⁻¹ (reached with seeds placed inside a closed cryogenic vial); ii) 1000 °C min⁻¹ (reached with aluminum-foiled seeds placed in a perforated cryogenic vial). For both methods, viability was maximum (83.3%) at a_w = 0.64. Lethal ice formation was responsible for the loss of viability at a_w>0.64 corresponding to the unfrozen water fraction. The use of higher cooling/warming rates enables a wider range of desiccation conditions (0.33<a_w<0.76) in cryopreservation procedures. This work contributes to the optimization of cryopreservation methods of economically important germplasm.     

Post-feeding thermophily in lizards (Lialis burtonis Gray,Pygopodidae): Laboratory studies can provide misleading results

Many ectothermic vertebrates raise their preferred body temperature after feeding, likely expediting digestion. However, most studies documenting this phenomenon have relied upon laboratory thermal gradients, which grossly oversimplify an animal's environment. We explored the validity of thermal gradient methodology by investigating post-prandial thermophily in an Australian pygopodid lizard (Lialis burtonis Gray). Mean body temperatures did not differ between fed and unfed lizards in field enclosures. Feeding influenced body temperature in a thermal gradient, but in opposite directions depending on details of the methodology. When we introduced L. burtonis into the gradient at the warmer end, fed lizards had higher body temperatures than unfed conspecifics. However, the opposite was true when lizards were introduced at the cooler end. These contrasting results indicate that lizards with food in their stomachs did not seek out higher temperatures, but instead were more sedentary than unfed lizards. Our study highlights the need for caution in interpreting thermal gradient results unaccompanied by field data, and it demonstrates how minor changes in equipment design or procedures can significantly alter conclusions from laboratory studies.     

Thermal manipulations during broiler embryogenesis improves post-hatch performance under hot conditions

Previous studies on broilers conducted in our laboratory showed that intermittent thermal manipulation (TM) of 39.5 °C every 12 h during embryonic days E7–E16 improved thermoregulative parameters in the embryo and post-hatch, as well as the broilers' ability to cope with heat challenge at marketing age. The aim of this study was to investigate the effect of intermittent TM of 39.5 °C (65% RH) for 12 h/d (12 H), during E7–E16, on post-hatch performance and thermoregulation under both optimal and hot conditions. Chicks from the control and TM treatments were raised under “regular” conditions until 21 d of age. Then, each treatment was divided into 2 sub-treatments (growth conditions) – optimal conditions (25 °C) and hot conditions of 32 °C for 12 h/d – until 35 d of age. Under optimal conditions, no difference in growth rates was found between TM and control throughout the growth period, but TM had significantly larger relative breast muscle weight, and on days 13, 25, and 35 breast muscle in the TM treatment contained a higher percentage of large-diameter fibers than controls. Consequently, average fiber diameter was significantly larger in TM than in control. Relative weight of the abdominal fat pad was significantly lower in the TM treatment than in control, under both environmental conditions. Hot conditions negatively affected growth rates of broilers in both treatments. The TM chickens showed no body-weight advantage over controls, nevertheless, feed conversion between days 21 and 35 was lower in the TM chickens of both sexes than in controls. This could be attributed to lower body temperature and lower plasma thyroid hormone levels found in the TM chickens, indicating lower heat production rates. Greater muscle growth and lower relative weight of abdominal fat pad were found in the TM chickens than in controls, under hot conditions. It can be concluded that TM during embryonic development improves performance as well as thermoregulation.     

Synthesis and properties of 4′-C-aminoalkyl-2′-fluoro-modified RNA oligomers

Synthesis and properties of double-stranded RNAs (dsRNAs) and small interfering RNAs (siRNAs) containing 4′-C-aminoethyl-2′-deoxy-2′-fluorouridine are described. Thermal denaturation studies showed that incorporation of 4′-C-aminoethyl-2′-fluoro analog improved the thermal stabilities of dsRNAs and siRNAs compared to the corresponding 4′-C-aminoethyl-2′-O-methyl analog. siRNA incorporating eight 4′-aminoethyl-2′-fluoro analogs in the passenger strand showed sufficient RNAi activity at 1?nM concentration, which was similar to that of the unmodified siRNA. Furthermore, the siRNA containing the 4′-C-aminoethyl-2′-fluoro analog exhibited high stability in a buffer containing 20% bovine serum. Forty-eight percent of the siRNA remained intact after 48?h of incubation. Thus, modification of siRNAs by the 4′-C-aminoethyl-2′-fluoro analog would be useful for the development of therapeutic siRNA molecules.     

The development of thermoregulation in turkey and guinea fowl hatchlings: similarities and differences

The development of thermoregulation was studied in turkeys (Meleagris gallopavo, 60.5 g) and guinea fowl (Numida meleagris, 33.5 g) from 2 to 24 h after hatching. Thermoregulation was measured at different ages during 1 h of cold exposure (20°C). Final body temperature rose linearly with age in turkeys, but reached a plateau in guinea fowl between 12 and 16 h. At 2 h after hatch final body temperature was highest in guinea fowl, while at 24 h after hatch there was no difference between the species. The development of mass-specific metabolic rate with age resembled the pattern of final body temperature. At 2 h post-hatch mass-specific metabolic rate was highest in guinea fowl; however, at 24 h post-hatch there was no difference between the species. since mass-specific metabolic rate reached a plateau in guinea fowl at 16 h. In turkeys mass-specific dry thermal conductance decreased with age initially, while in guinea fowl it remained stable. Nevertheless, at both 2 and 24 h after hatch mass-specific wet conductance did not differ significantly between the species. In turkeys mass-specific wet conductance increased initially. This increase in mass-specific wet conductance may be due to the rapid onset of feather growth in turkeys. The O₂ consumption per breath doubled during the first 24 h in turkeys but remained stable in guine fowl. This suggests that at least two different developmental patterns of O₂ intake exist within Galliformes. The results show that 2 h post-hatch the thermoregulatory ability was lowest in turkeys, despite their larger body mass. However, at 24 h post-hatch the difference between the species was not significant, because the thermoregulatory ability had increased more in turkeys.Abbreviations B _f breathing frequency - BM body mass - BMR basal metabolic rate - C _D mass-specific dry thermal conductance - C _w mass-specific wet thermal conductance - HI homeothermy index - H _E evaporative heat loss - H _B loss of stored body heat - MR metabolic rate - M _MS mass-specific metabolic rate - RH relative humidity - I _A ambient temperature - T _Bi initial body temperature - T _Bf final body temperature - VO₂ volume oxygen consumed - VCO₂ volume carbon dioxide produced     

The first two lanthanum-containing coordination polymers involving naphthalene-1,4,5,8-tetra-carboxylate as ligand

Reaction in an aqueous gel medium between a lanthanide ion and the sodium salt of the naphthalene-1,4,5,8-tetra-carboxylic acid can lead to coordination polymers. We report here the synthesis, the crystal structure, the thermal analysis and the calculated porosity of two new coordination polymers involving the lanthanum ion.The thermal properties of compound [LaNa[(C₁₀H₄)(COO)₄](H₂O)₇ · 4H₂O]_∞ have also been studied and are reported here.     

Schistosoma mansoni: factors affecting hatching of eggs

The effect of light, oxygen tension, reducing conditions and thermal shock on egg hatching in Schistosoma mansoni were examined. Hatching was found to be unaffected by light or dark conditions or aerobic or anaerobic conditions. Cold shock from 15 to 120 sec was also ineffective in stimulating hatching. The reducing agents ascorbic acid and cysteine inhibited egg hatching. However, the oxidized forms of these compounds inhibited hatching as well, indicating that the reducing conditions they provided were not responsible for the inhibition.     

Langevin dynamics of conformational transformations induced by the charge–curvature interaction

The role of thermal fluctuations in the conformational dynamics of a single closed filament is studied. It is shown that, due to the interaction between charges and bending degrees of freedom, initially circular chains may undergo transformation to polygonal shape.     

Behavioral thermoregulation in three Hawaiian reef fishes

Synopsis The preferred temperature of three Hawaiian coral-reef fishes — Acanthurus triostegus sandvicensis, Abudefduf abdominalis, and Chaetodon multicinctus — were determined in two-chambered tanks that permitted the fish to regulate behaviorally tank temperature. Median selected temperatures over 72 h were as follows: adult C. multicinctus, 24.0° C; juvenile C. multicinctus, 27.0° C; adult Ab. abdominalis, 25.9° C; juvenile Ab. abdominalis, 30.2° C; adult Ac. triostegus, 29.2° C; juvenile Ac. triostegus, 29.3° C. Juvenile Ab. abdominalis selected significantly higher median temperatures than the adults. C. multicinctus and juvenile Ab. abdominalis selected higher median temperatures during the day than at night.Based on the senior author's dissertation submitted to the Graduate School of the University of Hawaii in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Oceanography.Contribution No. 555 from the Hawaii Institute of Marine Biology, University of Hawaii, Honolulu, Hawaii.