Physiological traits as affected by heat stress in sheep—A review

Recent results continue to show the general consensus that ozone-related increases in UV-B radiation can negatively influence many aquatic species and aquatic ecosystems (e.g., lakes, rivers, marshes, oceans). Solar UV radiation penetrates to ecological significant depths in aquatic systems and can affect both marine and freshwater systems from major biomass producers (phytoplankton) to consumers (e.g., zooplankton, fish, etc.) higher in the food web. Many factors influence the depth of penetration of radiation into natural waters including dissolved organic compounds whose concentration and chemical composition are likely to be influenced by future climate and UV radiation variability. There is also considerable evidence that aquatic species utilize many mechanisms for photoprotection against excessive radiation. Often, these protective mechanisms pose conflicting selection pressures on species making UV radiation an additional stressor on the organism. It is at the ecosystem level where assessments of anthropogenic climate change and UV-related effects are interrelated and where much recent research has been directed. Several studies suggest that the influence of UV-B at the ecosystem level may be more pronounced on community and trophic level structure, and hence on subsequent biogeochemical cycles, than on biomass levels per se.

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Effects of solar UV radiation on aquatic ecosystems and interactions with climate change

Brown adipocytes are thermogenic cells which play an important role in energy balance. Their thermogenic activity is due to the presence of a mitochondrial uncoupling protein (UCP). Until recently, it was admitted that in rodents brown adipocytes were mainly located in classical brown adipose tissue (BAT). In the present study, we have investigated the presence of UCP protein or mRNA in white adipose tissue (WAT) of rats. Using polymerase chain reaction or Northern blot hybridization, UCP mRNA was detected in mesenteric, epidydimal, retroperitoneal, inguinal and particularly in periovarian adipose depots. The uncoupling protein was detected by Western blotting in mitochondria from periovarian adipose tissue. When rats were submitted to cold or to treatment with a beta-adrenoceptor agonist, UCP expression was increased in this tissue as in typical brown fat. Moreover, the expression was decreased in obese fa/fa rats compared to lean controls. Morphological studies showed that periovarian adipose tissue of rats kept at 24 degrees C contained cells with numerous typical BAT mitochondria with or without multilocular lipid droplets. Immunocytochemistry confirmed that multilocular cells expressed mitochondrial UCP. Furthermore, the number of brown adipocytes and the density of mitochondrial cristae increased in parallel with exposure to cold. These results demonstrate that adipocytes expressing UCP are present in adipose deposits considered as white fat. They suggest the existence of a continuum in rodents between BAT and WAT, and a great plasticity between adipose tissue phenotypes. The physiological importance of brown adipocytes in WAT and the regulation of UCP expression remain open questions.

Occurrence of brown adipocytes in rat white adipose tissue: molecular and morphological characterization.

Amphibians and agricultural chemicals: Review of the risks in a complex environment

Epidemiological evidence links an individual's susceptibility to chronic disease in adult life to events during their intrauterine phase of development. Biologically this should not be unexpected, ...

Placental Origins of Chronic Disease.

The diets of frugivorous and nectarivorous vertebrates contain much water and generally have high energy but low protein contents. Therefore, we tested the prediction that to save energy under conditions of high energy demands and high water intake, frugivorous Egyptian fruit bats (Rousettus aegyptiacus) will increase both the absolute quantity and the proportion of ammonia in their urine. We also examined whether such changes occur when protein intake is low and water intake is high. We did three feeding trials. In trials 1 and 2, bats were fed one of four liquid diets containing constant soy protein concentrations but varying in sucrose concentration and were kept at ambient temperatures (Ta) of 30°C and 12°C, respectively. In trial 3, bats were kept at \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra}...

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The influence of ambient temperature and the energy and protein content of food on nitrogenous excretion in the Egyptian fruit bat (Rousettus aegyptiacus).

Incubation temperature of the pigeon embryo (Columba livia)

In past studies, several rodent species of the murid subfamilies Gerbillinae and Cricetomyinae from the Namib Desert, when deprived of water, excreted allantoin precipitate in their urine. Shifting nitrogen excretion from urea to allantoin allows them to save much water. This phenomenon has not been reported in other rodents, and whether it is a trait that is common among desert rodents, but undocumented, or is unique to these Namib Desert spe- cies, is not known. We found no allantoin precipitate in the urine of any of five additional species of water-deprived murid rodents of two subfamilies from the Negev Desert. There was no discernible precipitate in the urine of Gerbillus andersoni allenbyi (Gerbillinae), Gerbillus pyramidum (Gerbillinae), or Acomys cahirinus (Murinae). Sodium oxalate was found in both the precipitate and the liquid urine of Psammomys obesus(Gerbillinae), and the as yet unidentified precipitate in the urine of Gerbillus dasyurus (Gerbillinae) was not allantoin. This preliminary study suggests that not all gerbilline rodents have the capacity to switch from urea to allantoin excretion. The Namib Desert gerbilline and cricetomyine rodents may be examples of closely related mammalian taxa that have evolved a new metabolic pathway to produce a nitrogenous product that results in sizable water savings, i.e., by switching from urea to allantoin. Resume : Des etudes anterieures ont demontre qu'en l'absence d'eau, plusieurs especes de rongeurs Muridae des sous- familles Gerbillinae et Cricetomyinae du desert de Namibie excretent des precipites d'allantoine dans leur urine. Le passage de l'excretion de l'azote sous forme d'uree a l'excretion sous forme d'allantoine leur permet d'epargner beau- coup d'eau. Le phenomene n'a pas ete signale chez d'autres rongeurs et on ne sait pas si c'est un caractere commun, mais pas encore signale, aux rongeurs des deserts ou alors une caracteristique particuliere des especes du desert de Na- mibie. Nous n'avons pas retrace la presence de precipites d'allantoine dans l'urine de cinq especes additionnelles de rongeurs murides des deux sous-familles provenant du desert du Neguev et privees d'eau. Il n'y avait pas de precipite decelable dans l'urine de Gerbillus andersoni allenbyi (Gerbillinae), ni de Gerbillus pyramidum (Gerbillinae), ni d'Aco- mys cahirinus (Murinae). Nous avons trouve de l'oxalate de sodium dans le precipite ainsi que dans l'urine liquide de Psammomys obesus(Gerbillinae), de meme qu'un precipite encore non identifie, mais qui n'est pas de l'allantoine, dans l'urine de Gerbillus dasyurus (Gerbillinae). Notre etude preliminaire indique que ce ne sont pas tous les rongeurs gerbillines qui sont capables d'excreter de l'allantoine au lieu de l'uree. Les rongeurs gerbillines et cricetomyines du desert de Namibie sont peut-etre des exemples de taxons de mammiferes tres apparentes qui ont developpe de nouvel- les voies metaboliques pour elaborer un produit azote qui entraine une conservation substantielle d'eau, i.e. en rempla - cant l'uree par l'allantoine. (Traduit par la Redaction) 945

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New observations on urine contents in water-deprived Negev Desert rodents

—among air-breathing vertebrates, aquatic turtles exhibit an exceptional capacity for prolonged submergence. Despite this ability, drowning occurs when a turtle entrapped in submerged fishing gear cannot reach the water surface. mortality in crab pots is the major threat to the Diamondback terrapin, Malaclemys terrapin. Data from laboratory experiments and field observations were integrated to estimate survival time for a terrapin submerged in a crab pot. voluntary dive time (8.4 ± 5.7 min) was compared to a calculated aerobic dive limit (caDl) derived from mass-specific lung volume and metabolic rates. by this estimate, a 200 g terrapin has sufficient oxygen stores to sustain aerobic metabolism for ~19 min at 20° c. these data suggest that voluntary dives are usually less than caDl. average submergence time for crab pots set in shallow tidal creeks greatly exceeded caDl and were longer for evening tides (310–365 min) than for morning tides (77–156 min) when water temperature was also higher (27–30° c vs. 24–25° c). terrapins captured in crab pots in the evening had higher plasma lactate concentrations than those caught in the morning. for both groups, lactate concentrations were reduced within 12 h. Without access to air, survival time is dependent on water temperature and activity level. a terrapin forcibly submerged in 27° c water is physiologically stressed within minutes and can reach a lethal lactacidosis in less than 12 h. conservation efforts should focus on trap designs that prevent entry or facilitate escape while retaining target species.

Itzick Vatnick

Papers

The influence of ambient temperature and the energy and protein content of food on nitrogenous excretion in the Egyptian fruit bat (Rousettus aegyptiacus).

Incubation temperature of the pigeon embryo (Columba livia)

New observations on urine contents in water-deprived Negev Desert rodents

Estimating survival times for Northern Diamondback Terrapins, Malaclemys terrapin terrapin, in submerged crab pots

Breeding and life cycle of the ornamental freshwater shrimp Neocaridina davidi in a biofilm‐based culture system