Rougiere N, Carre B. Muegge BD, Kuczynski J, Knights D, Clemente JC, Gonzalez A, Fontana L, Henrissat B, Knight R, Gordon JI. A common explanation for the origin of multiple gene copies is that these allow making more protein product (see Section Molecular mechanisms for differences in enzyme activities between populations/species). Forcella M, Berra E, Giacchini R, Parenti P. Leucine transport in brush border membrane vesicles from freshwater insect larvae. Bolognesi R, Terra WR, Ferreira C. Peritrophic membrane role in enhancing digestive efficiency: Theoretical and experimental models. Herbivores: Their Interaction with Secondary Plant Metabolites. For example, 75% of the cellulase activity in the GI tract of the termite Mastotermes darwiniensis can be assigned to microbial fermentation by protist symbionts in the hind gut, with the remainder accounted for by intrinsic enzymes in the midgut and salivary glands (453); but the cellulase activity in the GI tract of the beetle Tenebrio molitor was unaffected by elimination of the microbiota (174), indicating that the observed microbial fermentation does not make a necessary contribution to cellulose digestion. Helicoverpa larvae were also found to produce midgut proteases (85) or trypsin isoforms (313) that were either sensitive or insensitive to inhibition by soybean trypsin inhibitor (STI). [Data from reference (290)]. 16B) (43), and this effect could be reversed by transfer back to starch-free diet (44). Other SLC6 transporters have a very broad range. The diffusive component of intestinal glucose absorption is mediated by the glucose-induced recruitment of GLUT2 to the brush-border membrane. Pacha J. Many studies indicate that a variety of polyphenolics (mainly flavonoids) inhibit mediated glucose uptake by SGLT1 and/or GLUT2, based on experiments using intestine in situ, isolated tissue and cells, brush border membrane vesicles, and Xenopus laevis oocytes expressing the transporter proteins (307), and one study found that polyphenols depressed SGLT1 gene expression (351). Karasov WH, Diamond JM. Geurden I, Aramendi M, Zambonino-Infante J, Panserat S. Early feeding of carnivorous rainbow trout (, Ghadamyari M, Hosseininaveh V, Sharifi M. Partial biochemical characterization of alpha- and beta-glucosidases of lesser mulberry pyralid, Glyphodes pyloalis Walker (Lep. In addition to metabolic differences, the anatomical, physiological, and biochemical differences in the gastrointestinal (G.I.) Ontogenesis of intestine morphology and intestinal disaccharidases in chickens (. 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). 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). Fine KD, Santa Ana CA, Porter JL, Fordtran JS. The large intestine or hindgut encompasses four main sections. 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. Batchelor DJ, Al-Rammahi M, Moran AW, Brand JG, Li X, Haskins M, German AJ, Shirazi-Beechey SP. Careers, Unable to load your collection due to an error. The reviews by Buddington and colleagues in the early 1990s (49, 50, 54) summarized results for about 12 vertebrate species, and additional work in the past 15 years has resulted in many more studies of developmental changes in digestion and features of digestive physiology, as well as an expanded list of species including more than a dozen fish species (see below), six amphibian species, a turtle (35), five avian species, and a dozen mammals. Buddington RK. Study of the aminopeptidase N gene family in the lepidopterans. For example, in altricial house sparrows digestive biochemistry was dynamic over their 2-week period from hatching to fledging from the nest. There are small differences in a few organs. The first section is the duodenum. Drosophila NPC1b promotes an early step in sterol absorption from the midgut epithelium. In the field, the initial diet of nestling house sparrows is dominated by insects, but switches subsequently to seeds. (A) The dose-corrected plasma concentration of [3H]L-glucose as a function of time since American robins were injected (unfilled symbols) or gavaged (filled symbols) with the probe solution containing L-glucose. Expression cloning and cDNA sequencing of the Na+/glucose co-transporter. Despite the growing evidence for dynamic selective permeability of tight junctions, the predominance of transcellular transport has been attributed to the superior selectivity of transcellular transport via carrier-mediated transporters on the apical membrane of enterocytes, thereby protecting the animal from many toxins or otherwise deleterious compounds breaching the gut wall. Microbes and Health Sackler Colloquium: Composition, variability, and temporal stability of the intestinal microbiota of the elderly. Lactose is hydrolyzed by the membrane-bound intestinal enzyme lactase-phlorizin hydrolase (or lactase, for simplicity), which is coded by the lactase gene (LCT). Yadgary L, Yair R, Uni Z. Cattle and sheep can live on hay and pasture, while pigs must eat grains that can be digested more easily. In contrast, absorption of 3-Omethyl-d-glucose did not differ significantly between the taxa. Returning to mammals, a single proton-oligopeptide transporter, PEPT1 (member of SLC15A family) mediates the uptake of peptides across the apical membrane (Fig. Lipid absorption in insects differs from vertebrates in several important respects. German DP, Bittong RA. Cellulose, a glucose polymer linked by beta 14 bonds, is the most abundant carbohydrate in terrestrial ecosystems, but is a challenge to use as an energy source because it is degraded very slowly by enzymatic hydrolysis, often taking many hours (220). Flavonoid-drug interactions: Effects of flavonoids on ABC transporters. It seems reasonable that digestive SPswould be downregulated during nonfeeding stages or during fasting within a stage given the energy required to produce these proteins and to ensure that pupating larva are protected from spurious self digestion (306). to acquire those all. [Data from Fig. 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. There are four main types of teeth in the human or dog: incisors, canines, premolars and molars. Torrallardona D, Harris CI, Fuller MF. 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. While teeth serve the main role in grinding to reduce food size and increase surface area, the first action to begin the chemical breakdown of food occurs when feed is mixed with saliva.There are three main salivary glands, which include the parotid, mandibular and sub-lingual glands. Thomas KK, Nation JL. 1A of reference (330) and Fig. Paracellular absorption is important in many birds. Ferreira C, Parra JRP, Terra WR. Transcriptional and posttranscriptional adjustments mediate phenotypic changes in the expression of hydrolases and transporters in response to dietary signals. This issue has been explored particularly in relation to variation in the capacity of animal species with different diets to modulate their transporter activity. Research suggests antagonistic coevolution between plants and herbivores in which the plants produce a variety of PIs with specific action against different kinds of proteases and the animals produce digestive enzyme variants that are fairly insensitive to the PIs (237). The stomach has complex glandsin its wall. Increases in both SI activity and glucose transport occurred 2 days before hatch and at hatch day. How much DNA does a pig share with a human? Diacylglycerol generated by PLC2, together with the high Ca2+, activates PKCII, permitting the insertion of GLUT2 into the apical membrane and the resultant high capacity uptake of glucose and fructose. Paracellular transport refers to movement between cells of the gut epithelium, while the transcellular route involves transport across the apical cell membrane of gut epithelial cells, transit across the cell (for some molecules with metabolic transformations in the cell), and then export at the basolateral membrane. Wijtten PJA, van der Meulen J, Verstegen MWA. Bacterial cell walls are made primarily of peptidoglycan, which is hydrolyzed by the enzyme lysozyme. The human digestive system and a pig's digestive system are very similar to each other. Small intestine volume, a direct function of tube length and area, and consequently the potential mass of digesta carried, was relatively smaller in birds, by 32%. Carstea ED, Morris JA, Coleman KG, Loftus SK, Zhang D, Cummings C, Gu J, Rosenfeld MA, Pavan WJ, Krizman DB, Nagle J, Polymeropoulos MH, Sturley SL, Ioannou YA, Higgins ME, Comly M, Cooney A, Brown A, Kaneski CR, Blanchette-Mackie EJ, Dwyer NK, Neufeld EB, Chang TY, Liscum L, Strauss JF, III, Ohno K, Zeigler M, Carmi R, Sokol J, Markie D, ONeill RR, van Diggelen OP, Elleder M, Patterson MC, Brady RO, Vanier MT, Pentchev PG, Tagle DA. Subsequent sections cover mechanisms and patterns of variation across taxa in chemical digestion by animals and their microbiota, and absorption of breakdown products. The increased fructose transport activity coincides with increased abundance of mRNA and GLUT5 protein. Hourdry J, Lhermite A, Ferrand R. Changes in the digestive tract and feeding behavior of anuran amphibians during metamorphosis. Secor SM, Diamond JM. How and when selection experiments might actually be useful. As a library, NLM provides access to scientific literature. It can be seen that the human digestive tract is relatively small. For example, even when maintained on a carnivore type diet (55% protein, 10% lipid, and <4% carbohydrate), two species that naturally shift diet during development (Cebidichthys violaceus and Xiphister mucosus) increased -amylase and maltase activity as they grew, which indicates an intrinsic genetic developmental program matched well to their natural diet shift (178). Oxidative metabolism in the locust rectum. Thus, the cecotrophs that reach the stomach contain large amounts of lysozyme and, presumably, of bacteria with partially hydrolyzed cell walls ready to be digested. 5). Gisbert E, Gimenez G, Fernandez I, Kotzamanis Y, Estevez A. Post-feeding induction of trypsin in the midgut of. 10). Further research is required to determine the mechanisms underlying fermentation in these fish, and the nutritional significance of the SCFAs produced. None of them generated significant transport currents, which seems to be good direct evidence for lack of Na+-coupled transport via SGLT1. Variation in bacterial communities of mammals with diet, analyzed by principal components analysis. In theory, humans cannot incorporate lysine that might derive from isotope-labeled urea through proteins that the hindgut microbial community produces because they are hindgut fermenters and do not reingest feces. This class of lipid-related molecules is distinctive from other lipids in two important respects. Host-mediated induction of alpha-amylase by larvae of the Mexican bean weevil. Interplay between physiology and ecology in digestion. Mechanisms vary, including competitive (350) and noncompetitive (473) enzyme inhibition as well as disruptions of the emulsification process important in digestion of fat (401). This process occurs very rapidly. Fermentative degradation of complex carbohydrates by consortia of bacteria in the human colon. For humans and biomedical rodent models, the paracellular pathway makes a negligible contribution to absorption of many solutes. German DP. The molecular basis of sugar uptake across the gut wall has not, however, been investigated widely in the invertebrates. Geddes K, Philpott DJ. The STI-senstive trypsim isoforms were produced constitutively, but production of the induced STI-insensitive forms was regulated transcriptionally following ingestion of STI (313). For example, the magnitude of inhibition of plant cell-wall digestibility was 23% for essential oils, 11% for saponins, and 3% for tannins (all relative to controls). Liver - the human liver has four lobes: right, left, caudate and quadrate. 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). A. aegypti has three trypsin genes expressed in the midgut. Some of the food substrates listed in Table 2 are degraded mainly or entirely by enzymes from the GI microbiota, but the hosts intrinsic catalytic enzymes may nonetheless play a critical role in managing this symbiotic relationship and in harvesting useful products from it. 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.
