Fully reversible phenotypic plasticity of digestive physiology in young house sparrows: lack of long-term effect of early diet composition

Feeding conditions during the nestling period may significantly affect whole-life fitness in altricial birds but little is known about the physiological mechanisms responsible for these effects. Permanent changes (irreversible developmental plasticity) in digestive physiology caused by the neonatal diet may form such a mechanism. We previously showed that the lack of starch in the diet of house sparrow (Passer domesticus) nestlings between 3 and 12 days post-hatching significantly decreased the activity of intestinal maltase, an enzyme essential for starch digestion. To check whether diet-induced variation in maltase activity in young house sparrows is reversible, we raised them under laboratory conditions from 3 until 30 days of age on diets with either 0% starch or 25% starch, with some individuals experiencing a switch in their assigned diet at 12 days of age. We found evidence for the presence of an internal, presumably genetic, program for changes in the activity of maltase and sucrase, which was, however, significantly affected by diet composition (i.e. environmental factor). Digestive enzyme activity in 30 day old birds was not influenced by diet composition prior to day 12 but instead depended only on diet that was fed between days 12 and 30. We conclude that plasticity in the activity of intestinal disaccharidases in house sparrow nestlings represents completely reversible phenotypic flexibility that can help young sparrows to cope with unpredictable variation in food composition during ontogeny without long-term effects on their digestive system. However, comparison with other species suggests that the magnitude of digestive flexibility in young passerines may be evolutionarily matched to species-specific variation in feeding conditions.Fil: Brzęk, Pawel. University of Wisconsin; Estados Unidos. University of Bialystok; PoloniaFil: Kohl, Kevin D.. University of Wisconsin; Estados Unidos. University of Utah; Estados UnidosFil: Caviedes Vidal, Enrique Juan Raul. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Karasov, William H.. University of Wisconsin; Estados Unido

Activity of intestinal carbohydrases responds to multiple dietary signals in nestling House sparrows

The ‘adaptive modulation hypothesis’ predicts that activity of digestive enzymes should match the amount of their substrates in diet. Interestingly, many passerine birds do not adjust the activity of intestinal carbohydrases to dietary carbohydrate content. It is difficult to assess the generality of this rule, because in some studies passerines fed on low-carbohydrate and high-lipid diet showed reduced activity of intestinal carbohydrases. However, as carbohydrase activity may be inhibited by high dietary lipid content, it is unclear whether observed effects reflected lack of induction by the low carbohydrate levels or suppression by the high lipid levels. Here, we isolated the specific effects of dietary carbohydrate and lipid on carbohydrases. We hand-fed house sparrow nestlings on diets with 25% starch and 8% lipid (diet HS), no starch and 20% lipid (HL), or 25% starch and 20% lipid (HSL). Our results show that activity of intestinal carbohydrases is simultaneously induced by dietary carbohydrates and decreased by dietary lipid, although the latter effect seems stronger. Activities of maltase and sucrase summed over the total intestine decreased in the order HS>HSL>HL. We observed a complex interaction between diet composition and intestinal position for mass-specific activity of these enzymes, suggesting site-specific responses to changes in digesta composition along the intestines caused by digestion and absorption. We re-interpret results of earlier studies and conclude that there is no unequivocal example of adaptive modulation of intestinal carbohydrases by dietary carbohydrate in adult passerine birds, whereas the present experiment confirms that nestlings of at least some species possess such capacity.Fil: Brzek, Pawel. University of Wisconsin. Department of Forest and Wildlife Ecology; Estados UnidosFil: Kohl, Kevin D.. University of Wisconsin. Department of Forest and Wildlife Ecology; Estados UnidosFil: Caviedes Vidal, Enrique Juan Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. University of Wisconsin. Department of Forest and Wildlife Ecology; Estados Unidos. Universidad Nacional de San Luis. Facultad de Ciencias Humanas. Laboratorio de Biología "Profesor Enrique Cavides Codelia"; ArgentinaFil: Karasov, William H.. University of Wisconsin. Department of Forest and Wildlife Ecology; Estados Unido

Effects of PCB 126 and Ammonia, Alone and in Combination, on Green Frog (Rana clamitans) and Leopard Frog (R. pipiens) Hatching Success, Development, and Metamorphosis

The Green Bay watershed in Wisconsin is polluted with polychlorinated biphenyls (PCBs), dioxin, heavy metals, ammonia, and over 100 organic contaminants. In this study we exposed embryos and larvae of two ranid species commonly occurring in the Green Bay ecosystem, the green frog (Rana clamitans) and the leopard frog (R. pipiens), to PCB 126 (3,3\u27, 4,4\u27, 5-Pentachlorobyphenil, nominal concentrations 0-50 μg/l, two control treatments: water plus 0.08% acetone as carrier for the PCB, water alone), unionized ammonia (0-2 mg/I), and mixtures of both contaminants. Exposure to PCB 126 did not cause significant mortality of embryos before hatching. However, exposure to unionized ammonia (NH3) concentrations in excess of 0.6 mg/I (green frogs) or 1.5 mg/I (leopard frogs) caused a decline in hatching success and an increase in prevalence of deformities. PCB 126 and NH3 in combination had a significant negative effect on hatching success. Survival of larvae was significantly reduced at the highest PCB concentration (50 mg/I) for both species. Few skeletal deformities were observed in tadpoles at this concentration, but the incidence of edema was significantly increased. A slowing of growth was also observed in anuran tadpoles exposed to PCB 126. NH3 exposure caused a decrease in the survival and growth of green frog tadpoles. When exposed to mixtures of both chemicals, green frog tadpoles showed a decrease in survival. However, growth was not affected. Fewer tadpoles metamorphosed with increasing PCB 126 and NH3 concentrations. In tadpoles exposed to PCB 126, tissue concentrations of PCB 126 at the end of the experiment increased with increasing nominal concentrations, ranging from 1.2-9600 ng/g wet weight. Our data indicate that anurans may not be particularly sensitive to NH3 as compared to many fish species, and that water quality criteria determined using data collected on fish species will be protective for many anuran amphibians. At high concentrations, PCB 126 and unionized NH3 affected both ranid species. However, no sublethal effects were apparent at water concentrations that occur in the Green Bay ecosystem

Chickadees faced with unpredictable food increase fat reserves but certain components of their immune function decline

In winter, temperate resident birds are often faced with periodic low natural food availability. This reduction or unpredictability in resource availability might then have a negative impact on immune function, given that immune system support is highly resource dependent. We investigated the balance between energetic and immune management in captive black-capped chickadees (Poecile atricapilus) by manipulating the predictability of resources. The control group received food ad lib. every day, while the experimental group received a reduced amount of food on random days and food ad lib. on all other days. We measured two key metrics of energetic management (body and fat mass) as well as a suite of immune system components. Compared with control birds, experimental birds maintained significantly higher total body and fat mass, had lower acute phase protein concentrations, and had decreased body temperature and lost more body mass during the fever response following injection with lipopolysaccharides. Interestingly, birds in both groups had similar levels of complement lysis, delayed-type hypersensitivity response (phytohemagglutinin), and primary antibody production (keyhole limpet hemocyanin). This experiment demonstrates that black-capped chickadees strategically increase their fat mass in response to decreased food availability and that this might allow the birds to maintain most of the immune system unaltered, except some of the most costly immune components

A fast and accurate method to identify and quantify enzymes in brush-border membranes: In situ hydrolysis followed by nano LC-MS/MS

A simple method for the identification of brush-border membrane α-glucosidases is described. The proteins were first solubilized and separated in a gel under native, non-denaturing, conditions. The gel was then incubated in substrate solutions (maltose or sucrose), and the product (glucose) exposed in situ by the oxidation of o-dianisidine, which yields a brown-orange color. Nano-liquid chromatography coupled to mass spectrometry analyses of proteins (nano LC-MS/MS) present in the colored bands excised from the gels, was used to confirm the presence of the enzymes. The stain is inexpensive and the procedure permits testing several substrates in the same gel. Once enzymes are identified, their abundance, relative to that of other proteins in the brush border, can be semi-quantified using nano LC-MS/MS.Fil: Brun, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Magallanes Alba, Melisa Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Martínez del Rio, Carlos. University of Wyoming; Estados UnidosFil: Barrett Wilt, Gregory. University of Wisconsin; Estados UnidosFil: Karasov, William H.. University of Wisconsin; Estados UnidosFil: Caviedes Vidal, Enrique Juan Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentin

Duplications and functional convergence of intestinal carbohydrate-digesting enzymes

Vertebrate diets and digestive physiologies vary tremendously. Although the contribution of ecological and behavioral features to such diversity is well documented, the roles and identities of individual intestinal enzymes shaping digestive traits remain largely unexplored. Here, we show that the sucrase-isomaltase (SI)/maltase-glucoamylase (MGAM) dual enzyme system long assumed to be the conserved disaccharide and starch digestion framework in all vertebrates is absent in many lineages. Our analyses indicate that independent duplications of an ancestral SI gave rise to the mammalianspecific MGAM, as well as to other duplicates in fish and birds. Strikingly, the duplicated avian enzyme exhibits similar activities to MGAM, revealing an unexpected case of functional convergence. Our results highlight digestive enzyme variation as a key uncharacterized component of dietary diversity in vertebrates.Fil: Brun, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Mendez Aranda, Daniel. Max Planck Institute für Ornithologie; AlemaniaFil: Magallanes Alba, Melisa Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Karasov, William H.. University of Wisconsin; Estados UnidosFil: Martínez del Rio, Carlos. University of Wyoming; Estados UnidosFil: Baldwin, Maude W.. Max Planck Institute für Ornithologie; AlemaniaFil: Caviedes Vidal, Enrique Juan Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentin

High paracellular nutrient absorption in intact bats is associated with high paracellular permeability in perfused intestinal segments

Water-soluble nutrients are absorbed by the small intestine via transcellular and paracellular mechanisms. Based on a few previous studies, the capacity for paracellular nutrient absorption seems greater in flying mammals than in nonflying mammals, but there has been little investigation of the mechanisms driving this difference. Therefore, we studied three species each of bats (Artibeus lituratus, Sturnira lilium and Carollia perspicillata) and nonflying mammals (Akodon montensis, Mus musculus and Rattus norvegicus). Using standard pharmacokinetic techniques in intact animals, we confirmed the greater paracellular nutrient absorption in the fliers, comparing one species in each group. Then we conducted in situ intestinal perfusions on individuals of all species. In both approaches, we measured the absorption of 3OMD-glucose, a nonmetabolizable glucose analog absorbed both paracellularly and transcellularly, as well as l-arabinose, which has no mediated transport. Fractional absorption of l-arabinose was three times higher in the bat (S. lilium: 1.2±0.24) than in the rodent (A. montensis: 0.35±0.04), whereas fractional absorption of 3OMD-glucose was complete in both species (1.46±0.4 and 0.97±0.12, respectively). In agreement, bats exhibited two to 12 times higher l-arabinose clearance per square centimeter nominal surface area than rodents in intestinal perfusions. Using l-arabinose, we estimated that the contribution of the paracellular pathway to total glucose absorption was higher in all three bats (109–137%) than in the rodents (13–39%). These findings contribute to an emerging picture that reliance on the paracellular pathway for nutrient absorption is much greater in bats relative to nonflying mammals and that this difference is driven by differences in intestinal permeability to nutrient-sized molecules.Fil: Brun, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Price, Edwin R.. University Of Wisconsin; Estados UnidosFil: Gontero Fourcade, Manuel Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Fernández Marinone, Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; ArgentinaFil: Cruz Neto, Ariovaldo P.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Caviedes Vidal, Enrique Juan Raul. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Karasov, William H.. University of Wisconsin; Estados Unido

Non-invasive measurement of metabolic rates in wild, free-living birds using doubly labelled water

Please read abstract in the article.DST-NRF Centre of Excellence at the FitzPatrick Institute for African Ornithology; National Research Foundation of South Africa, Grant/Award Number: 110506; Universities of Cambridge and Zurich; MAVA Foundation, ERC, Grant/Award Number: 294494; University of Pretoria; The Oppenheimer Memorial Trust, Grant/Award Number: OMT 20747/01http://wileyonlinelibrary.com/journal/fechj2020Mammal Research InstituteZoology and Entomolog

Paracellular absorption is relatively low in the herbivorous Egyptian spiny-tailed lizard, Uromastyx aegyptia

Extent: 9 p.Absorption of small water-soluble nutrients in vertebrate intestines occurs both by specific, mediated transport and by nonspecific, passive, paracellular transport. Although it is apparent that paracellular absorption represents a significant route for nutrient absorption in many birds and mammals, especially small, flying species, its importance in ectothermic vertebrates has not previously been explored. Therefore, we measured fractional absorption (e) and absorption rate of three paracellular probes (arabinose, L-rhamnose, cellobiose) and of 3-O-methyl D-glucose (absorbed by both mediated and paracellular pathways) by the large herbivorous lizard, Uromastyx aegyptia, to explore the relative importance of paracellular and mediated transport in an ectothermic, terrestrial vertebrate. Fractional absorption of 3-O-methyl D-glucose was high (e = 0.7360.04) and similar to other vertebrates; e of the paracellular probes was relatively low (arabinose e = 0.3160.03, Lrhamnose e = 0.1960.02, and cellobiose e = 0.1460.02), and decreased with molecular mass, a pattern consistent with other vertebrates. Paracellular absorption accounted for approximately 24% of total 3-O-methyl D-glucose uptake, indicating low reliance on this pathway for these herbivorous lizards, a pattern similar to that found in other terrestrial vertebrates, and different from small flying endotherms (both birds and bats).Todd J. McWhorter, Berry Pinshow, William H. Karasov and Christopher R. Trac