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31.3. Acclimation to hydric stress in birds: A field and alaboratory study
Sabat, P.Departamento deCiencias Ecológicas, Universidad deChile, Chile
Carbon stable isotope ratios can be used as indicators of diet(marine vs. terrestrial) and as indirect indices of the salt loadsexperienced by birds consuming marine and terrestrial inverte-brates. We compared the carbon isotopic composition andosmoregulatory capacities of field caught individuals of fiveCinclodes (Passerine, Furnariidae) species in Chile. Thedifferences in carbon isotopic composition among these specieswere paralleled by differences in osmoregulatory character-istics. Birds consuming marine invertebrates exhibits moreconcentrated blood plasma and produce more concentrate urinein the field. We also investigated latitudinal variation in therenal traits that mediate how these birds cope with dehydrationand a salty marine diet. The species increased the incorporationof terrestrial carbon, as measured by 13C, as terrestrialproductivity increased southwards. The osmoregulatory traitsof both species varied with latitude as well. Urine's osmolalitydecreased from extremely high values in the north to moderatevalues in the south. In both species, the proportion of kidneydevoted to medullary tissue decreased from north to south, andkidney size increased significantly with latitude. Variation in thereliance on marine food sources at inter- and intraspecific scaleseems to be accompanied by adjustments in the osmoregulatorymechanisms used by these birds to cope with salt anddehydration. However, differences in kidney morphologyalong the gradient may be the result of phenotypic plasticityor population differentiation. Hence, we investigated theresponse of three Cinclodes species to acclimation experimentsto two regimes of salinity for 15 days. Our results indicate thatspecies of Cinclodes are able to modify the proportion ofmedullary tissue and the Umax. The effect of exposure to fresh-or saltwater on medullary size, however, was relatively small(22%) and smaller than the differences found along theextremes of the latitudinal gradient and among species(120%). These experiments suggest that phenotypic flexibilityin adult birds is unlikely to explain all the variation in renal traitsobserved along the latitudinal gradient and among Cinclodesspecies. However, we cannot yet discount the possibility thatexposure to different environments during early developmentcontributes to latitudinal variation in renal traits.
doi:10.1016/j.cbpa.2007.06.334
31.4. Diet and energetics in mammals: Phenotypic integrationand flexibility
Cruz-Neto, A.Department of Zoology, UNESP – Rio Claro, SP, Brazil
The food-habit hypothesis attempts to explain in an evolu-tionary time-scale the effects of diet quality, availability andpredictability on basal metabolic rate (BMR). Albeit attrac-tive, there are several problems and ambiguities in the resultsthat attempted to test this hypothesis. Ambiguities surround-ing diet categorization and the use of coarse classificationsbased on aridity or continuous measures of climate variablesof the species' habitat of origin as a proxy to infer theproductivity of the habitat can potentially confounds inter-pretations from interspecific analysis of the food-habithypothesis. Finally, and superimposed on these problems,interspecific analysis, by assuming that species are fixedentities, neglect the role played by phenotypic flexibility inproviding a fine-tuned adjustment of BMR to changes in dietquality, availability of predictability. In this review, I willpresent three intraspecific studies carried out with bats,rodents and marsupials where specific aspects of the food-habit hypothesis were tested. Such studies, besides solvingsome of the problems mentioned, allow for direct analyses ofhow BMR changes as a function of diet quality, availabilityand predictability and, thus, may provide a more thoroughtest of this hypothesis. These results also shows thatrelationship between diet quality and BMR at the proximatelevel can not be easily predicted from interspecific analysis,as the outcomes depends on a complex integration of thephenotypic plasticity observed in behavioral, morphologicaland physiological traits.
doi:10.1016/j.cbpa.2007.06.335
31.P1. Gut size flexibility in laboratory mice and rats: A meta-analysis
Naya, D.E., Karasov, W.H., and Bozinovic, F.Pontif ícia Universidad Católica de Chile, Chile
Gut flexibility has been suggested as one of the mostimportant physiological adjustments to changes in environ-mental conditions. Here we demonstrate, through a quantita-tive review of the evidence for laboratory mice and rats, thatgut length flexibility is highly significant for adjustment topregnancy, lactation, and change in diet quality, while gut drymass flexibility is highly significant for adjustments to thesefactors plus changes in environmental temperature. Inagreement with previous ideas, we observed that lactationcauses larger adjustments in small intestine size than doespregnancy and adjustment to lower temperature. We alsodemonstrate that flexibility in hindgut length is greater forchange in diet quality than it is for changes in energydemanding factors such as pregnancy and low environmentaltemperature. In addition, we found a clear positive relation-ship between the amount of increase in small intestine size
S133Abstracts / Comparative Biochemistry and Physiology, Part A 148 (2007) S132–S137
and the number of pups reared during lactation. In summary,in most of the cases, the present analysis confirms previousideas on gut size flexibility, giving a strong quantitativesupport for them. In a few instances the analysis pointed outsome incongruence with previous results that should befurther explored.
doi:10.1016/j.cbpa.2007.06.336
31.P2. Effects of Sodium tetraborate on some biological fitnessparameters of Galleria mellonella L. (Lepidoptera;Pyralidae)
Buyukguzel, K. and Durmu, Y.Faculty of Science, Karaelmas University, Turkey
The effects of sodium tetraborate on survival, development,adult longevity, and fecundity of greater wax moth Galleriamellonella L. were investigated by rearing the larvae onartificial diets. The highest concentration of sodium tetraborate(0.3 g) significantly decreased the survival rate of 7th instars to17.5±2.9% and prolonged the time required to reach 7th instarby 5 days. The diet containing this concentration produced12.5% of both pupae and adult yields and also prolongeddevelopment by 5 days. When compared to adult longevity(9.0±0.7 days) from control diets, adults reared with 0.2 gof sodium tetraborate survived by about 4.2 days longer(13.2±1.9 days). The highest concentration of sodium tetra-borate resulted in decreased adult longevity in comparison tocontrol. Diet containing 0.005 and 0.2 g sodium tetraborateconcentrations caused a significant decrease in egg productionand hatchability of G. mellonella females. Oviposition ofsurvivors in highest sodium tetraborate treatment (0.3%) wascompletely inhibited. From a practical standpoint, sodiumtetraborate incorporated into a bait appears to be an idealreplacement for insecticides with high toxicity to environmentand nontargets. We infer that survival, development, longevityand fecundity are effective biological fitness parameters forassessing toxicity of this boron compound.
doi:10.1016/j.cbpa.2007.06.337
31.P3. Some biological fitness and biochemical parameters ofPimpla turionellae adults reared on hosts exposed toethyl parathion
Büyükgüzel, E. and Açýkgöz, P.Faculty of Science, Karaelmas University, Turkey
We investigated effects of organophosphorus insecticide, ethylparathion on survival, development and some biochemical
parameters of endoparasitoid Pimpla turionellae (L.) reared onhost insect, greater wax moth, Galleria mellonella (L.) pupae.Newly hatched larvae of G. mellonella were orally exposed to0.01, 0.1, 1.0 and 10 ppm of the insecticide by rearing on anartificial diet. The pupae emerged from these larvae were usedas ethyl parathion-contaminated hosts for P. turionellae. Asbioindicators of long-term physiological stress responses tosuch hosts, survival and development of the parasitoids wereassessed. Furthermore, alterations in activities of variousenzymes involved in certain metabolic functions such asalanine aminotransferase (ALT), aspartate aminotransferase(AST), acetylcholinesterase (AChE), acid phosphatase (ACP),lactate dehydrogenase (LDH), gamma glutamyl transferase(GGT), glucose-6-phosphate dehydrogenase (G6PDH), andcontent of total protein (TP) and lactate (LAC) were determined.Ethyl parathion did not significantly affect the survival while alltested concentrations caused significant increase in timerequired to reach fifth instar. Significant reduction in postlarvalsurvival and increase in developmental time were obtained forhigh concentrations of the insecticide. At 10 ppm, ethylparathion significantly reduced adult survival from 70.3% incontrol diet to 30.8% and caused a significant prolongation inadult development by about 4 days. All tested concentrations ofethyl parathion significantly increased total protein content andactivities of AST and GGT while only 0.1 ppm and aboveresulted in increased ALTactivity. The activities of ACP, AChE,G6PDH were decreased by all concentrations of ethylparathion. However, the insecticide at 0.1 ppm and aboveresulted in decreased lactate content and LDH activity. The totalprotein content in control group (15±1.3) was increased by thelowest concentration of ethyl parathion to 180±7.3 mg/g of wetweight. These results indicate ethyl parathion not only impairneurotransmission but also disturb various metabolic functions.This study infer that ethyl parathion-induced metabolicdysfunctions is a causal factor in deterioration of survival anddevelopment of P. turionellae.
doi:10.1016/j.cbpa.2007.06.338
31.P4. Environmental factors influence dietary fractionation ofstable isotopes in hissing cockroaches
McCue, M.D.Biological Sciences, University of Arkansas, USA
The past decade has witnessed a dramatic increase in thenumber of physiological studies that utilize stable isotopes. Theincreased use of isotope ratio mass spectrometry (IRMS) amongphysiological ecologists most likely results from three factorsincluding integration of continuous-flow and automatedtechnologies which have increased throughput and reducedcosts, changing perceptions and legislation dealing with the useof radioactive materials in free-living animals, and an increased
S134 Abstracts / Comparative Biochemistry and Physiology, Part A 148 (2007) S132–S137