Effect of D-glucose on intestinal permeability and its passive absorption in human small intestine in vivo. Co-adaptations of feeding behaviours and gut modulation as a mechanism of co-existence. Development of disaccharidase activity in the small intestine of broiler chickens. Karasov WH, Caviedes-Vidal E, Hartman Bakken B, Izhaki I, Samuni-Blank M, Arad Z. These adjustments can occur within individuals in a wide variety of herbivorous animals, including endothermic mammals and birds (246, 296) and ectothermic insects (482), and crabs (295), and perhaps in cockles (Cerastoderma edule) switched from phytoplankton to detritus (338). This pattern, first described in a survey of more than 40 species drawn from the major vertebrate classes (245), is apparent also in comparative studies within fish (51) and birds (247). 30 generations) of cecal valves, which slow down food passage and provide for fermenting chambers, among lizards (Podarcis melisellensis) that were introduced onto an island where they consumed eight times more vegetation than did individuals in their source population. Altmann SW, Davis HR, Jr, Zhu LJ, Yao X, Hoos LM, Tetzloff G, Iyer SP, Maguire M, Golovko A, Zeng M, Wang L, Murgolo N, Graziano MP. Lysozyme hydrolyzes the bacterial cell walls and the defensins insert into membranes where they interact with one another to form pores that disrupt membrane function and lead to the death of the bacterial cell (268). In the wood eating termite Reticulitermes speratus, for example, intrinsic cellulase gene expression is much reduced in reproductives compared with workers (399), and protease levels are much reduced in colony members of ants, wasps, and honeybees that are fed amino-acid-rich excretions of other colony members (159, 218). Schondube JE, Martinez del Rio C. Sugar and protein digestion in flowerpiercers and hummingbirds: A comparative test of adaptive convergence. Ribonucleases, secreted by the exocrine pancreas into the lumen of the small intestine, digest the abundant RNAs of rapidly growing bacteria. -amylases (hydrolyzes starch from plants and glycogen from animals). Of particular importance are: (a) the intrinsic capacity of the animal to degrade complex polysaccharides and (b) diet composition. Kwon O, Eck P, Chen SL, Corpe CP, Lee JH, Kruhlak M, Levine M. Inhibition of the intestinal glucose transporter GLUT2 by flavonoids. 18). Cholesterol molecules that are not esterified in the endoplasmic reticulum are eliminated from the enterocyte to the intestinal lumen and voided via the feces. Flavonoid-drug interactions: Effects of flavonoids on ABC transporters. Regulation of gut function varies with life-history traits in chuckwallas (Sauromalus obesus: Iguanidae), Tsahar E, Friedman J, Izhaki I. Darias MJ, Murray HM, Gallant JW, Douglas SE, Yufera M, Martinez-Rodriguez G. Ontogeny of pepsinogen and gastric proton pump expression in red porgy (, Darias MJ, Zambonino-Infante JL, Hugot K, Cahu CL, Mazurais D. Gene expression patterns during the larval development of European sea bass (, Dash MC, Nanda B, Mishra PC. McSweeney CS, Palmer B, McNeill DM, Krause DO. Freund J-N, Jost B, Lorentz O, Duluc I. The central role of transporters in the modulation of absorption with diet raises important questions about the capacity of an animal to regulate uptake of nutrients with significant levels of passive absorption. The tips of the microvilli form web-type structures called glycocalyx.Amino acids and simple sugars released into the brush border membrane are absorbed into the microvilli first, then into the villi, and then pass into the circulatory system. Foye OT, Black BL. Despite the poor capacity of the domestic cat to utilize diets with significant levels of carbohydrate, many commercial cat diets contain relatively high levels of carbohydrate. Dyer J, Al-Rammahi M, Waterfall L, Salmon KS, Geor RJ, Boure L, Edwards GB, Proudman CJ, Shirazi-Beechey SP. The enzyme activities were downregulated in insects on diets containing an excess of the substrate. Furthermore, AMY1 copy number and salivary amylase protein levels in humans generally are at least three times higher than in chimpanzees and bonobos, whose diets are composed predominantly of fruit and leaves that contain much less starch than the diets of most human populations. In mammals, a steep diffusion gradient across the apical membrane is generated by acyl-CoA:cholesterol acyltransferase (ACAT2)-mediated esterification of cholesterol in the enterocyte (Fig. sharing sensitive information, make sure youre on a federal Among animals that consume refractory food types there are multiple strategies. This process occurs very rapidly. A powerful way to study these recovery processes is to track isotopically labeled compounds (168). Sundset MA, Barboza PS, Green TK, Folkow LP, Blix AS, Mathiesen SD. Genetic and phenotypic adaptation of intestinal nutrient transport to diet in fish. Mandal S, Ghosh K. Inhibitory effect of Pistia tannin on digestive enzymes of Indian major carps: An in vitro study. In rats, SGLT1 (primary D-glucose transporter) is expressed before birth whereas GLUT5 (fructose transporter) is first expressed only during or after weaning. Patra AK. Digestive physiology: A view from molecules to ecosystem. The esophagus,stomach,liver . Nevertheless, there is substantial evidence for extensive paracellular transport of solutes in flying birds and fruit bats. The dominant lipids in most diets are triacylglycerols (TAGs), accompanied by small amounts of various polar and nonpolar lipids, including phospholipids, sterols, and the fat-soluble vitamins A and E. The products of lipid digestion include free FAs, glycerol, monoglycerides, and lysophospholipids. Over early time points, the amounts of L-glucose absorbed was 50% to 70% of the amounts of D-glucose absorbed, which was interpreted to mean that the majority of glucose was absorbed by the paracellular pathway. Turning to the relationship between diet and microbial fermentation, various studies suggest that the taxonomic composition and metabolic traits of the gut microbiota can be influenced by diet, potentially with effects on the digestive function of the GI tract. Apparent transcription control of SP activity was also demonstrated in the scarabaeid beetle Costelytra zealandica (306). Remis MJ, Dierenfeld ES. Novakova R, Homerova D, Kinne RKH, Kinne-Saffran E, Lin JT. (ii) The lipids synthesized in all insect enterocytes studied to date are dominated by DAGs, not TAGs; and sterols appear to be absorbed without esterification in the enterocyte (442). Second, although intestinal tissue-specific rates of hydrolysis and nutrient absorption typically do not change significantly, the total hydrolytic and absorptive capacity of the small intestine does increase because of the increase in intestinal mass. The key glucose transporters in mammals and birds (184) are a Na+/glucose cotransporter SGLT1 (a member of the Na+/solute symporter family) and the facilitative transporter GLUT2, which transports glucose, fructose, mannose, and galactose with low affinity and N-acetyl-glucosamine with high affinity (444). (248). There was no marked pattern of higher intestinal transport activity for amino acids among the more carnivorous vertebrate species (245, 246). Consumption of sugars, hemicellulose, starch, pectin and cellulose by the grasshopper. There are only a few differences between the circulatory system of an adult pig and a fetal pig, besides from the umbilical arteries and vein. Among humans sampled by Perry et al. 8600 Rockville Pike For example, this effect has been confirmed in rodents for all of the major pancreatic enzymes (amylase, lipase, and proteases) and enzymes of the intestinal brush border (sucrase-isomaltase, maltase-glucoamylase, and aminopeptidase-N) (246). This condition is not, however, universal among insects. This reduced pH kills bacteria ingested with the feed. But, microbes potentially provide their hosts more than those energy-rich fermentation products. The difference in intestinal surface area between birds and nonflying mammals did not depend on diet in the analysis. Walthall K, Cappon GD, Hurtt ME, Zoetis T. Postnatal development of the gastrointestinal system: A species comparison. Kinetic analyses of nutrient uptake indicate that the diet-dependent variation in sugar and amino acids transporter activity is mediated predominantly by changes in the density of transporters on the apical membrane (149). In: Rosenthal GA, Janzen DH, editors. Poelstra K, Bakker WW, Klok PA, Hardonk MJ, Meijer DKF. government site. Terpenoid compounds, including essential oils and saponins (glycosides of terpenes and steroids), appear to have the largest negative effects, based on a meta-analysis of 185 treatments in ruminants in 36 studies (357). The mouth serves a valuable role not only for the consumption of food but it also provides for the initial partial size reduction though grinding. Digestive enzyme activities and gastroin-testinal fermentation in wood-eating catfishes. Culture-independent characterization of the microbiota of the ant lion Myrmeleon mobilis (Neuroptera: Myrmeleontidae). However, a deep analysis of the both would reveal the existing difference . For example, many of the carbohydrate-degrading enzymes are correlated positively with dietary carbohydrate level in fish, birds, and mammals (246), crustaceans (235, 236, 389), oligochaetes (110), and possibly insects (94). Getachew G, Pittroff W, Putnam DH, Dandekar A, Goyal S, DePeters EJ. In humans and other mammals, all regions of the GI tract are colonized, including the highly acidic stomach, which bears a diverse community of bacteria and some fungi (30). Binding of phlorizin to the isolated C-terminal extramembranous loop of the Na+/glucose cotransporter assessed by intrinsic tryptophan fluorescence. Zaneveld JR, Lozupone C, Gordon JI, Knight R. Ribosomal RNA diversity predicts genome diversity in gut bacteria and their relatives. These data lead to an expectation that they will reduce diet digestibility (26). Ontogenetic changes in digestive enzyme activity of the spiny lobster. Buddington RK, Chen JW, Diamond JM. Identify structures that are a part of the digestive system, respiratory system, circulatory system, reproductive system, and excretory system. Lavin SR, Karasov WH. Ohkuma M, Noda S, Hongoh Y, Nalepa CA, Inoue T. Inheritance and diversification of symbiotic trichonymphid flagellates from a common ancestor of termites and the cockroach Cryptocercus. (Diet did have a significant effect on gut size, but the effect was on cecal and large intestine size.) Our review complements and updates many earlier reviews (248, 249) to provide broader taxonomic coverage, and incorporates increased molecular information to characterize further the mechanistic bases of patterns of change within and across species. Notwithstanding the diversification of digestive systems caused by diversity among foods, Jumars and Penry (1987) pointed out that most guts can be analyzed as one of three categories of ideal chemical reactors, or combinations of them: batch reactors (e.g., the gastric cavity of a hydra and the blindended cecum of a rabbit), plug-flow reactors (PFRs; e.g., the tubular intestine of many invertebrates and all vertebrates), and continuous-flow stirred tank reactors (CSTRs; e.g., the rumen of a cow or the hindgut of a termite) (Fig. The sucrase-isomaltase (SI) gene was expressed 6 days before hatch, but expression of SGLT1 mRNA was not detected until 2 days before hatch (Fig. Slansky F, Scriber JM. (iv) The role of transporters in the absorption of lipidic compounds in insects is poorly studied, although a NPC-like transporter, NPC1b, has been demonstrated to mediate sterol uptake from the midgut of Drosophila (456), and a fatty acid transporter on the apical membrane has been invoked (63). Mott CR, Siegel PB, Webb KE, Wong EA. Common cutworms (Spodoptera litura; Lepidoptera), a highly polyphagous pest of subtropical and tropical crops, can be used to illustrate a pattern that is probably common (488). Huber K, Roesler U, Muscher A, Hansen K, Widiyono I, Pfeffer E, Breves G. Ontogenesis of epithelial phosphate transport systems in goats. (1) and (2), is the response to increases in energy demand as occurs in endothermic birds and mammals when temperature is reduced, or during reproduction. Lysine synthesized by the gastrointestinal microflora of pigs is absorbed, mostly in the small intestine. Because of this, it has been argued that they are not typically disruptors of intrinsic breakdown processes in either insects (26) or monogastric mammals (409). Phloretin (an aglycone) and phloridzin (its glycoside), members of the flavonoid subclass chalcones, are used as inhibitors of GLUT-2 and SGLT-1 respectively, in glucose absorption studies. Modeling has also contributed to understanding impacts of temperature change (297, 474) that could improve predictions of animal responses to climate change (13). Evolution of regulatory responses to feeding in snakes. Dierenfeld E, Hintz H, Robertson J, Van Soest P, Oftedal O. 12). The populations were geographically widely distributed and the interpopulation variation in copy number was related most strongly to diet and not geographic proximity. Whelan CJ, Brown JS, Schmidt KA, Steele BB, Willson MF. The examples described above illustrate that the digestive system can be viewed as economical in design, achieving a good match to food intake. Activity increases markedly for sucrase-isomaltase, maltase-glucoamylase, trehalase, and GLUT-5, the fructose transporter, in most cases accompanied by increases in the expression of their genes. GLUT5 expression is elevated in isolated rat intestine preparations perfused with fructose (425); horses fed on diets with high levels of digestible carbohydrate display elevated expression of SGLT1 in both the duodenum and ileum (133); and piglets raised on isoenergetic diets with different concentrations of digestible carbohydrate exhibit elevated expression of SGLT1 when fed on diets with more than 50% digestible carbohydrate (330) (Fig. Infante JLZ, Cahu CL. The stomach secretes acid, result- ing in a low pH of 1.5 to 2.5. The majority of humans are lactose intolerant, but members of a small number of populations that have been associated historically with domestic ungulates (cows, sheep, and goats) are lactose tolerant. Chen H, Pan YX, Wong EA, Webb KE. Song J, Kwon O, Chen SL, Daruwala R, Eck P, Park JB, Levine M. Flavonoid inhibition of sodium-dependent vitamin C transporter 1 (SVCT1) and glucose transporter isoform 2 (GLUT2), intestinal transporters for vitamin C and glucose. Among animals that consume foods with low amounts of refractory material(s), a key feature of digestive design for efficiency is hydrolytic and absorptive capacities matched to the relative amounts of carbohydrates, protein, and fats in their diets, as discussed in subsequent sections. This equation can be used only as a first approximation because it assumes constancy in many parameters that can be relatively complicated functions of each other [see references (239, 361), for examples of these functions]. Molecular characterization of the first aromatic nutrient transporter from the sodium neurotransmitter symporter family. An ecological and evolutionary perspective on human-microbe mutualism and disease. In the mouse, the responsiveness of GLUT2 insertion to luminal sugars varies among sugars, being triggered much less efficiently by glucose and complex sugars than by fructose, sucrose, and a mixture of glucose and fructose (193); mice fed on a high-fructose diet have been reported to bear GLUT2 permanently on the apical membrane of enterocytes (434). In this section, the relationship between diet composition and digestive enzyme activity is addressed first, followed by consideration of transporters in the GI tract. Allometry and ecology of feeding behavior and digestive capacity in herbivores: A review. Linton SM, Greenaway P. A review of feeding and nutrition of herbivorous land crabs: Adaptations to low quality plant diets. 6 minute read. But, as has been demonstrated many times, some glycosylated and nonglycosylated flavonoids did show structure-dependent inhibition of glucose transport. These included an abundantly expressed gene ApSt3, a hexose uniporter with specificity for glucose and fructose in the distal midgut. Kinetic analysis of butyrate transport in human colon adenocarcinoma cells reveals two different carrier-mediated mechanisms. Juan ME, Turmo MC, Planas JM. Transport of glucose and fructose across the mammalian enterocyte by SGLT1, GLUT2, and GLUT5. SGLT1 mRNA from references (405, 446). Ferreira AHP, Ribeiro AF, Terra WR, Ferreira C. Secretion of beta-glycosidase by middle midgut cells and its recycling in the midgut of. For example, in altricial house sparrows digestive biochemistry was dynamic over their 2-week period from hatching to fledging from the nest. Returning to mammals, a single proton-oligopeptide transporter, PEPT1 (member of SLC15A family) mediates the uptake of peptides across the apical membrane (Fig. Saliva generally contains very low levels of amylase, the enzyme that hydrolyses starch to maltose. If a young mammal is allowed to prolong suckling, or is fed on a lactose-containing diet after weaning, the onset of the decline in lactase is delayed, but only slightly. Usnic acid, a secondary metabolite of lichens and its effect on, Pankoke H, Bowers MD, Dobler S. Influence of iridoid glycoside containing host plants on midgut beta-glucosidase activity in a polyphagous caterpillar, Spilosoma virginica Fabricius (Arctiidae). Lipophilic toxins are also anticipated to permeate membranes passively at rates positively related to their octanol or oil:water partition coefficients, which was found to be the case in a survey of 36 flavonoids using Caco-2 cell monolayers (431). Sklan and colleagues (404406, 445, 446) and Planas and colleagues (16, 413) have studied the molecular basis for ontogenetic changes in carbohydrate digestion and absorption in chickens during the week before and after hatching. The evidence that these correlations represent evolutionary transitions is based on the bats diets mapped onto their hypothesized phylogeny, shown on the left. Thus, we end with a short list of some of the potential areas for future research. Pathways of amino acid recycling depend on gut design and animal behavior. Yu DD, Xiao ZZ, Liu QH, Xu SH, Ma DY, Li J, Webb KA. Comp Biochem Physiol A Mol Integr Physiol. Diurnal variation of GLUT2 and Pept-1 is regulated by the vagus nerve, and GLUT5 by paracrine and endocrine signals in the intestine (371, 427). Some new proteolytic enzymes are produced, such as pancreatic trypsin and stomach pepsin and chitinase(s) (217), which increase the capacity to digest animal matter. Martinez del Rio C. Sugar preferences in hummingbirds: The influence of subtle chemical differences on food choice. Jakobsson HE, Jernberg C, Andersson AF, Sjolund-Karlsson M, Jansson JK, Engstrand L. Short-term antibiotic treatment has differing long-term impacts on the human throat and gut microbiome. The suite of reactions responsible for the transformation of complex carbohydrates to SCFAs is mediated by consortia of multiple bacteria with complementary capabilities (156), with cross-feeding of intermediate metabolites among bacteria with different capabilities (Fig. Konarzewski M, Koyama S, Swierubska T, Lewonczuk B. This trait is believed to be linked to the high K+/low Na+ conditions in the gut of these insects, which eat plants with high ratios of K+/Na+. Gastrointestinal responses to fasting in mammals: Lessons from hibernators. Turnbaugh PJ, Hamady M, Yatsunenko T, Cantarel BL, Duncan A, Ley RE, Sogin ML, Jones WJ, Roe BA, Affourtit JP, Egholm M, Henrissat B, Heath AC, Knight R, Gordon JI. We begin with an overview of the architecture of animals guts, including a description of simple integrative models that have advanced understanding of how gut size, digesta flow, and biochemical capacity are matched to food intake to achieve efficient nutrient extraction. The alimentary canal forms one part of the digestive system, and it is the long tubular canal that runs from mouth to anus. Modeling has facilitated research that links digestive physiology with whole animal nutrition in production agriculture with vertebrates (380, 384) and aquaculture with invertebrates (376), and with ecological phenomena such as foraging ecology (298, 468) and community structure (353, 469). It has been estimated that the digestive tract and liver of a vertebrate accounts for 20% to 25% of the whole animals respiration (66, 308). The glucose transporter SGLT1 is expressed in the intestine of both the domestic dog and cat, but its expression level is twofold greater and is more responsive to dietary carbohydrate in the dog than the cat (18, 52). Comparative Biochemistry and Physiology of Enzymatic Digestion. Fowler HG, Forti LC, Brandao CRF, Delabie JHC, Vasconcelos HL. Figure 20. Hepatocyte nuclear factor-1 alpha, GATA-4, and caudal related homeodomain protein Cdx2 interact functionally to modulate intestinal gene transcription. Day AJ, Canada FJ, Diaz JC, Kroon PA, McLauchlan R, Faulds CB, Plumb GW, Morgan RA, Williamson G. Dietary flavonoid and isoflavone glycosides are hydrolysed by the lactase site of lactase phlorizin hydrolase. The activity of -chymotrypsin and -amylase in the gastrointestinal tract of the locust L. migratoria fed on diets of different composition: PC (21% protein:21% carbohydrate), pc (10.5% protein: 10.5% carbohydrate), Pc (35% protein: 7% carbohydrate), and pC (7% protein: 35% carbohydrate). It is not known whether such genetic or phenotypic adaptive response to dietary glycosides occurs in a vertebrate species. Martinez del Rio C. Dietary, phylogenetic, and ecological correlates of intestinal sucrase and maltase activity in birds. For example, in response to high dietary supply of sugars, the expression of genes encoding the transporters SGLT1 (for glucose) and GLUT5 (for fructose) is increased. Mackie RI. Absorbed amino acids and simple sugars are taken directly to the liver via the portal vein. The cotransport of the K+ ions and amino acid into enterocytes is coupled to the ATPase-dependent extrusion of K+ ions from adjacent goblet cells. Bifano TD, Samuels RI, Alexandre D, Silva CP. Arts ICW, Sesink ALA, Hollman PCH. Recent advances in sequencing technologies are transforming our capacity to study the diversity and function of the gut microbiota, and we consider these general issues first. Sugar transporters of the major facilitator superfamily in aphids; from gene prediction to functional characterization. The cdxA protein, which was shown in an electrophoretic mobility shift assay to bind to the promoter region of SI in chicks (as it does in mammalssee Section Flexible adjustment of digestive enzymes to diet change), also rose during these few days prehatch (Fig. Learn more about Biochek's diagnostic offering, Tips for diagnosis, prevention and control. Cellulase (cellulose is hydrolyzed by the concerted action of three types of cellulases: endocellulases, exocellulases, and -glucosidases). The caecum has two sections, first a section that has a blind end, where material can not pass though. Remarkably, however, nitrogen-15 labeled lysine appears in human plasma proteins hours after labeled urea is administered (168). 8A). Also, B-vitamins are synthesised in the large intestine and are absorbed in a very limited amount, but not significant to alter nutritional supplementation of them.With the majority of water removed, the digesta is condensed into a semi-solid material and is passed out of the rectum and anus. Guilloteau P, Zabielski R, Hammon HM, Metges CC. Shishikura Y, Khokhar S, Murray BS. These final products diffuse across the animal gut wall, and are used as substrates for aerobic respiration, gluconeogenesis, and lipogenesis in the animal. In: Starck JM, Wang T, editors. (423, 424) showed that usnic acid was apparently degraded in the rumen, and characterized a resistant bacterium that they proposed be named Eubacterium rangiferina. Ramirez-Otarola N, Narvaez C, Sabat P. Membrane-bound intestinal enzymes of passerine birds: Dietary and phylogenetic correlates. Gilbert ER, Li H, Ernmersonj DA, Webb KE, Wong EA. Pigs have a relatively simple, single-chambered stomach (monogastric). Carbohydrates in fish nutrition: Digestion and absorption in postlarval stages. Mascolo N, Rajendran VM, Binder HJ. The most important similarities between the pig and human digestive tracts are: the structure of the villi and the types of cells that constitute the intestinal epithelium, the ratio of. Uldry M, Ibberson M, Hosokawa M, Thorens B. GLUT2 is a high affinity glucosamine transporter. Intestinal development in neonatal calves: Effects of glucocorticoids and dependence on colostrum feeding. Specific regulation of intestinal nutrient transporters by their dietary substrates. Mutualistic fermentative digestion in the gastrointestinal tract: Diversity and evolution. The mechanism of chylomicron assembly is reviewed by reference (227). Eisert R. Hypercarnivory and the brain: Protein requirements of cats reconsidered. As the name suggests, this system is responsible for circulating blood and nutrients throughout the body. An interesting illustration of some of the variability in patterns of development comes from a comparison of patterns for two major sugar transporters, SGLT1 and GLUT5 (148). Match. Recent findings about intestinal alkaline phosphate (IAP) have provided new insights about the former function, and intestinal lysozyme and pancreatic ribonuclease are key components of the latter function. The heart of a pig is four-chambered. Accessibility Two of the bat genera (Mormoops and Pteronotus) are in a sister family, Mormoopidae. Nonruminant animals such as rats depend on the microbial community in the cecum and colon to incorporate urea-nitrogen into lysine. Karasov WH, Cork SJ. Molecular basis for the resistance of an insect chymotrypsin to a potato type II proteinase inhibitor. The next system to go over is the integumentary system-the skin. Tannin-binding proteins in saliva of deer and their absence in saliva of sheep and cattle. Diamond JM, Karasov WH. Nutritional programming of gastrointestinal tract development. Surprisingly, the ratio of intestinal glucose uptake to proline uptake, which is an index for the relative capacity for glucose and proline absorption, did not change between bullfrog tadpoles and adults and was characteristic of vertebrate carnivores (436). There are four basic types of digestive systems: monogastric, avian, rumi- nant, and pseudo-ruminant. Dreon MS, Ituarte S, Heras H. The role of the proteinase inhibitor ovorubin in apple snail eggs resembles plant embryo defense against predation. Regional expression and dietary regulation of rat small intestinal peptide and amino acid transporter mRNAs. They are taken up by NCP1L1 into enterocytes, but they are not esterified by ACAT2 and are eliminated via ABCG5/G8. Lactose is hydrolyzed by the membrane-bound intestinal enzyme lactase-phlorizin hydrolase (or lactase, for simplicity), which is coded by the lactase gene (LCT). Food intake rate and excreta egestion rate are related to the flow rate of digesta through the gut/reactor that, in relation to its size, determines retention time: Thus, conversion or extraction efficiency should be reciprocally related to flow rate. Miller MM, Popova LB, Meleshkevitch EA, Tran PV, Boudko DY. Ontogenetic changes related to carbohydrate digestion and absorption in chicks. Lavin SR, McWhorter TJ, Karasov WH. For dietary components such as nonstructural carbohydrates (e.g., sugars and starch), protein and lipids, a positive relationship is predicted between their level in the natural diet and the presence or amount of gut enzymes and transporters necessary for their breakdown and absorption (245, 248). -glucosidase activity has also been measured in guts of numerous invertebrates (5, 143, 151, 157, 183, 374, 391). First, they have lower hydrophobicity than long-chain fatty acids. In nestling sparrows fed on a diet containing starch, the gut maltase activity of the birds increased by more than twofold (Fig. Accelerated fat absorption in intestinal alkaline phosphatase knockout mice. The entire digestive tract is relatively simple in terms of the organs involved, which are connected in a continuous musculo-membanous tube from mouth to anus. Ontogeny of pancreatic enzymes in larval red drum Sciaenops ocellatus. Diet and the evolution of human amylase gene copy number variation. Post-feeding induction of trypsin in the midgut of. Developmental changes in morphometry of the small intestine and jejunal sucrase activity during the first nine weeks of postnatal growth in pigs. Development of lipase activity in yolk membrane and pancreas of young turkeys. In that tissue, lysozyme and other bactericidal proteins called defensins are secreted by Paneth cells located at the base of intestinal crypts (367). For example, the elevated expression of intestinal sucrase-isomaltase gene in the intestine of rats and mice fed on high-carbohydrate diets is controlled by the transcription factors Cdx-2 and HNF-1 (36); and the recruitment of these transcription factors to the promoter region is correlated with the acetylation of histones H3 and H4 associated with this gene (215). The SLC nomenclature was devised by the Human Genome Organization for transporters in the human genome (with all members of each family having >20%25% amino acid sequence homology), and is widely used for other animals. Study of the aminopeptidase N gene family in the lepidopterans. Although measuring the magnitude of these matches and the corresponding spare capacity, measured as the ratio of capacity to load, is plagued by a number of problems (66, 435, 466), estimates by a variety of methods in mammals and birds imply that immediate spare capacity (i.e., prior to any acclimation or acclimatization), is less than two (250).
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