The enzyme may be stored in the plant, in which case maceration by a consumer causes release of the aglycone toxin, or the enzyme might be a component of the consumers physiological processes such as intrinsic digestive enzymes or microbial enzymes (202). The relative merits of pre- and postgastric fermentation have been discussed extensively (421, 450). 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. Sweet taste receptors in rat small intestine stimulate glucose absorption through apical GLUT2. In three precocial species [chickens (33, 348), wild jungle fowl (231), ducks (256)] tissue-specific enzyme, and transport rates were constant or declined with age but overall digestive and absorptive capacity increased, along with intestine mass, in direct proportion to metabolic body mass, which was the pattern described for mammals. Cattle and sheep have three additional chambers before the true stomach. But, one of the congeneric but obligate carnivores (Xiphister atropurpureus) also increased -amylase without a diet shift, which suggested that phylogeny plays a role. Cloning and functional expression of the first eukaryotic Na+-tryptophan symporter, AgNAT6. Muegge BD, Kuczynski J, Knights D, Clemente JC, Gonzalez A, Fontana L, Henrissat B, Knight R, Gordon JI. Many frogs [e.g., references (436, 470)] shift from primarily herbivory to insectivory/carnivory coincident with a large decrease in length of the gut and the number of gut coils. Bowen SH. Lipolytic activities in developing turbot larvae as influenced by diet. In addition, preexisting pools of transporter proteins, probably localized in the cytosol, are likely localized to the membrane; this can achieve more rapid changes in transporter activity than changes in gene expression. Arjamaa O, Vuorisalo T. Gene-culture coevolution and human diet. Cuvier-Peres A, Kestemont P. Development of some digestive enzymes in Eurasian perch larvae. There are four main types of teeth in the human or dog: incisors, canines, premolars and molars. Two forms of carrier-mediated transport are recognized: facilitated diffusion, which is energy-independent and mediates transport down the electrochemical potential gradient; and active transport, which is concentrative and dependent, directly or indirectly, on cellular energy. 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). In analogous studies in rats (443), dogs (277), and humans (154) L-glucose, and hence passive absorption, is quantitatively much less important, confirming the likely phylogenetic difference between birds and mammals in the importance of paracellular transport. There is evidence that some flavonoid glycosides may be transported by SGLT-1 (10, 82, 274, 459), which could potentially lead to competitive inhibition of glucose transport. The pancreas is involved with both exocrine and endocrine excretions. Figure 20. The first section is the duodenum. For example, digestion time (and glucose absorption) was reduced when sunbirds ingested nectar from tobacco plants that contain particular alkaloids (426). Simple diffusion, that is, down the concentration gradient and involving neither a carrier nor cellular energy, is an additional mode of absorption that is especially important for small, nonpolar molecules. F represents females and M represents males. Beubler E, Juan H. Effect of ricinoleic acid and other laxatives on net water flux and prostaglandin E release by the rat colon. 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. However, limited microbial enzymes activity does occur in the large intestine, which forms VFAs (volatile fatty acids). Due to the differences in the digestive systems, cattle can utilize different types of feeds than pigs. Bile salts, which are the active portion of bile in the digestion process, primarily assist in the digestion and absorption of fat but also help with absorption of fat-soluble vitamins and aids pancreatic lipase in the small intestine. Enattah NS, Sahi T, Savilahti E, Terwilliger JD, Peltonen L, rvela I. Buddington RK, Chen JW, Diamond JM. Mosaic evolution of ruminant stomach lysozyme genes. These data lead to an expectation that they will reduce diet digestibility (26). Tight junction pore and leak pathways: A dynamic duo. Bacterial communities associated with the digestive tract of the predatory ground beetle, Poecilus chalcites, and their modification by laboratory rearing and antibiotic treatment. The assimilation of bacterial protein by herbivorous birds is perplexing because birds do not seem to have spatial separation of culturing and digestion of microbes. Amino Acid Transport Systems in the Mammalian Intestine [Data From Table 1 of Reference (41)]. However, a deep analysis of the both would reveal the existing difference . Bolognesi R, Terra WR, Ferreira C. Peritrophic membrane role in enhancing digestive efficiency: Theoretical and experimental models. Native microbial colonization of Drosophila melanogaster and its use as a model of Enterococcus faecalis pathogenesis. In addition, it has been argued (214) that it would be advantageous for herbivores with relatively rapid gut throughput to have compensatorily higher biochemical capacity to process proteins and recover them rather than excrete them. Dierenfeld E, Hintz H, Robertson J, Van Soest P, Oftedal O. For example, an animal derives more energy from simple sugars by gastric digestion and assimilation than by microbial fermentation; and more nitrogen from protein by gastric processing than microbial metabolism. A proportion of the SCFAs taken up is metabolized to lactate and ketonic acids (including acetoacetate and 3-hydroxybutyrate); these products are transported from the basolateral membrane of epithelial cells, probably via MCT1, to the blood. Yang RB, Xie CX, Fan QX, Gao C, Fang LB. Ontogenesis of digestive functions and nutritional requirements in marine fish larvae. Corby-Harris V, Pontaroli AC, Shimkets LJ, Bennetzen JL, Habel KE, Promislow DE. Lavin SR, Karasov WH. Free amino acids are taken up from the small intestine of mammals by multiple carriers with overlapping specificities, with the result that most individual amino acids are transported by more than one transporter. Ontogeny of gastrointestinal tract in hybrid flounder jasum. 10). Scores of specific essential oils have been tested and found to be inhibitory against many bacterial genera (2), and in the meta-analysis, they and saponins also appeared to inhibit protozoal growth (357). For example, genome annotation of the pea aphid Acyrthosiphon pisum revealed no Na+/solute symporter with plausible specificity for sugars, but 29 candidate sugar transporters in the MFS family, equivalent to GLUT (368). A comparative study of amylases and proteinases in some decapod Crustacea. Herbivores: Their Interaction with Secondary Plant Metabolites. A genomic view of the human-Bacteroides thetaiotaomicron symbiosis. Morphometrics of the avian small intestine compared with that of nonflying mammals: A phylogenetic approach. The relationship between the degradative capabilities of the bacteria in the GI tract and diet is further vividly illustrated by the discovery of genes for porphyranases and agarases in the gut bacterium Bacteroides plebeius isolated from Japanese but not North American individuals (207). Amino acid transporters are also expressed in the apical membrane of the insect hindgut epithelium, where they mediate the uptake of amino acids in the primary urine produced in the Malpighian tubules. Proteinase inhibitors. Evolutionary physiology. Transcriptional induction of diverse midgut trypsins in larval. Capacity for absorption of watear-soluble secondary metabolites greater in birds than in rodents. In contrast, absorption of 3-Omethyl-d-glucose did not differ significantly between the taxa. Shen L, Weber CR, Raleigh DR, Yu D, Turner JR. (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). The gut models derived from chemical reactor theory and applied to both invertebrates and vertebrates have been useful research tools that delineate the important digestive features, show the direction and strength of their interactions, and help achieve the desired integration by relating the features and their interactions to whole-animal feeding rate and extraction efficiency. This is not necessarily the case for increased glucose-transport activity, which may occur without a coinciding large increase in SGLT1 mRNA in rats and in lamb intestine [though see reference (294)]. The integration of digestion and osmoregulation in the avian gut. Effective discrimination of these alternatives requires simultaneous measurement of all the variables, as has been done in a number of studies with birds and mammals (248). 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). Two of the bat genera (Mormoops and Pteronotus) are in a sister family, Mormoopidae. Juan ME, Turmo MC, Planas JM. Soriano ME, Planas JM. Digestive kinematics of suspension-feeding bivalves: Modeling and measuring particle-processing in the gut of Potamocorbula amurensis. This can result in reduced nutritional gain from high-quality foods. Their functions include communication, attraction, or in defense against herbivores, predators, pathogens, and competitors (202). The pancreas serves as the most vial organ in the digestive process for producing and secreting enzymes needed for the digestion of chyme and the prevention of cell damage due to pH.In addition to the pancreas secreting into the duodenum, bile, which is stored in the gall bladder and produced by the liver, is secreted as well. Karasov and colleagues measured total absorption (mediated and passive) of D-glucose or 3OMD-glucose and passive absorption of L-glucose in intact animals by a standard pharmacokinetic methodology, for example, references (78, 244, 278, 280). By contrast, peptides are taken up by a single transporter with very low selectivity, as considered at the end of this section. Terra WR, Ferreira C. Insect digestive enzymes - properties, compartmentalization and function. Binder HJ. Goldberg RF, Austen WG, Zhang XB, Munene G, Mostafa G, Biswas S, McCormack M, Eberlin KR, Nguyen JT, Tatlidede HS, Warren HS, Narisawa S, Millan JL, Hodin RA. Basic design of vertebrate gut. The activity of lysozyme in the stomach of the foregut fermenters is over three orders of magnitude higher than that found in animals with no foregut fermentation. The alimentary canal forms one part of the digestive system, and it is the long tubular canal that runs from mouth to anus. Mott CR, Siegel PB, Webb KE, Wong EA. Pancreatic and intestinal carbohydrases are matched to dietary starch level in wild Passerine birds. Dyer J, Al-Rammahi M, Waterfall L, Salmon KS, Geor RJ, Boure L, Edwards GB, Proudman CJ, Shirazi-Beechey SP. In most mammals lactase activity is high at birth and declines sharply around weaning. They can interact with proteins and other macromolecules in vitro through hydrogen bonding and hydrophobic bonds, and thus bind enzymes and their nutrient substrates. Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource. Erban T, Hubert J. Digestive function of lysozyme in synanthropic acaridid mites enables utilization of bacteria as a food source. The transport of nutrients that are metabolized for energy production increase with increasing dietary supply, while those mediating the uptake of essential but non energy-yielding nutrients tend to decrease with increasing dietary supply. 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. That's where pigs can play an important role. Other SLC6 transporters have a very broad range. In: Starck JM, Wang T, editors. Fine KD, Santa Ana CA, Porter JL, Fordtran JS. Nutritional ecology of marine herbivorous fishes: Ten years on. Porter EM, Bevins CL, Ghosh D, Ganz T. The multifaceted Paneth cell. van Soest PJ. Hagerman AE, Butler LG. 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. These include the ABC transporters such as multidrug resistance proteins and permeability glycoprotein, or P-glycoprotein. German DP, Horn MH. Lavin SR, Karasov WH, Ives AR, Middleton KM, Garland TJ. tract of the human and common laboratory animals can cause significant variation in drug absorption from the oral route. Rumen-like methanogens identified from the crop of the folivorous South American bird, the hoatzin (Opisthocomus hoazin). Doring F, Will J, Amasheh S, Clauss W, Ahlbrecht H, Daniel H. Minimal molecular determinants of substrates for recognition by the intestinal peptide transporter. Unexpected similarity of intestinal sugar absorption by SGLT1 and apical GLUT2 in an insect (Aphidius ervi, Hymenoptera) and mammals. Until weaning, the stomach of the neonate is not acidic and substantial amounts of gastric and pancreatic proteases are not expressed. 8600 Rockville Pike For many years its natural substrate(s) were not known, but its presence was widely used in intestinal studies as a marker of the apical brush border and as a marker for crypt-villus differentiation (276). Berge KE, Tian H, Graf GA, Yu L, Grishin NV, Schultz J, Kwiterovich P, Shan B, Barnes R, Hobbs HH. Developmental changes in glucose transport, lipid composition, and fluidity of jejunal BBM. The gastrointestinal tract as a nutrient balancing organ. Human Anatomy and . 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. 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). Caco-2 cells display a third pathway that allows the passage of molecules up to 0.13 nm diameter, suggesting an additional route in the mammalian gut intestine (448). Drosophila NPC1b promotes an early step in sterol absorption from the midgut epithelium. Wilson-OBrien AL, Patron N, Rogers S. Evolutionary ancestry and novel functions of the mammalian glucose transporter (GLUT) family. The hollow organs that make up the GI tract are the mouth, esophagus, stomach, small intestine, large intestine, and anus. Nutritional development of feeding strategies in arctic ruminants: Digestive morphometry of reindeer. Protease inhibitors can permeabilize the peritrophic membrane of caterpillars (326). Morais S, Lacuisse M, Conceicao LEC, Dinis MT, Ronnestad I. Ontogeny of the digestive capacity of (S. Moran AW, Al-Rammahi MA, Arora DK, Batchelor DJ, Coulter EA, Ionescu C, Bravo D, Shirazi-Beechey SP. Nonesterified sterol is eliminated into the gut lumen via ATP-binding cassette (ABC) transporters ABCG5 and ABCG8. Many of these patterns are apparent in at least a dozen other species of mammals that have been studied, although in species such as carnivorous marine mammals and ruminants sucrase activity remains low (246), and in ruminants dramatic changes occur in GI tract structure postnatally [i.e., development of multichambered foregut (257, 258)] coordinated with changes in gene expression (97). Generally these provide only enough energy to assist in the nutrient requirements of the epithelium of the large intestine. Hummel J, Sudekum KH, Streich WJ, Clauss M. Forage fermentation patterns and their implications for herbivore ingesta retention times. Infante JLZ, Cahu CL. The mucosa is comprised of finger-like projection called villi, which in turn contain more micro-size projections called microvilli. 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. Posthatch changes in SI activity also seemed correlated with changes in SI mRNA, suggesting that SI expression is transcriptionally controlled (446). Fujita AI. : Pyralidae). Discrimination between cholesterol and sitosterol for absorption in rats. 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). Miyauchi S, Gopal E, Fei YJ, Ganapathy V. Functional identification of SLC5A8, a tumor suppressor down-regulated in colon cancer, as a Na(+)-coupled transporter for short-chain fatty acids. Their findings help explain earlier findings that rumenal microbiota from reindeer performed better at in vitro digestion when usnic acid was added, whereas addition of usnic acid to sheep rumenal microbiota depressed digestion (355). Cummings JH, Macfarlane GT. Cano M, Ilundain AA. Prudence M, Moal J, Boudry P, Daniel JY, Qur C, Jeffroy F, Mingant C, Ropert M, Bdier E, Van Wormhoudt A, Samain JF, Huvet A. Terra WR, Ferreira C. Biochemistry of digestion. Kimmich GA, Randles J. Phloretin-like action of bioflavonoids on sugar accumulation capability of isolated intestinal cells. Buchon N, Broderick NA, Chakrabarti S, Lemaitre B. Invasive and indigenous microbiota impact intestinal stem cell activity through multiple pathways in Drosophila. Karasov WH, Levey DJ. 1A of reference (330) and Fig. 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. Hamilton I, Rothwell J, Archer D, Axon TR. Mites that consume plant materials have higher levels of glycosidases (examples in Table 2) than those that live on animal secretions or blood (345), which is a pattern analogous to the correlation postulated above between carbohydrate-digesting enzymes and dietary carbohydrate. Hourdry J, Lhermite A, Ferrand R. Changes in the digestive tract and feeding behavior of anuran amphibians during metamorphosis. Ranges are given for the following food types: ne, nectar; vf, vertebrate flesh; wv, whole vertebrates; in, whole invertebrates; se, seeds; fr, fruit; ve, vegetation (grass, dicot leaves, and twigs); de, detritus. The duodenum is approximately 12 inches long and is the portion of the small intestine that ducts from the pancreas and the liver (gall bladder). Ontogenetic changes in digestive enzyme activity of the spiny lobster. Bernays EA, Driver GC, Bilgener M. Herbivores and plant tannins. Increases in both SI activity and glucose transport occurred 2 days before hatch and at hatch day. Influence of diet on the structure and function of the bacterial hindgut community of crickets. They suggested that this is the reason why tubular guts predominate among complex, multicellular animals. Remarkably, the composition of the microbiota and gene expression profile was altered within a single day of transferring the mice from a low-fat diet with high plant polysaccharide content to a high-fat, high-sugar diet (441). The expression of SGLT1 in the intestine is restricted to the apical membrane of enterocytes. Nestlings of song thrushes (Turdus philomelos) and house sparrows removed from their nests could be overfed less than 20% as compared with controls (controls = nestlings fed amounts that yielded a growth rate similar to that of wild nestlings), and their modest increases in food intake were offset by statistically significant or near-significant declines in digestive efficiency as compared with controls (266, 286). Saliva secretion is a reflex act stimulated by the presence of food in the mouth. A chymotrypsin-like serine protease cDNA involved in food protein digestion in the common cutworm, Zhang HZ, Malo C, Boyle CR, Buddington RK.
