Initial production (within 3 h of feeding) is from a preformed mRNA, in response to protein in the blood; and subsequent production (810 h after feeding) comes from de novo trypsin gene expression, induced by amino acid products of trypsin-mediated digestion of blood proteins (146). In pigs, the circulatory system is composed of the heart, blood, and the blood vessels. Unexpected similarity of intestinal sugar absorption by SGLT1 and apical GLUT2 in an insect (Aphidius ervi, Hymenoptera) and mammals. 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. All Rights Reserved | No part of this site may be reproduced without permission. Narisawa S, Huang L, Iwasaki A, Hasegawa H, Alpers DH, Millan JL. Shishikura Y, Khokhar S, Murray BS. The analysis was conducted on 106 individuals of 60 species from 13 orders of mammals. 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). Decreased polyphenol transport across cultured intestinal cells by a salivary proline-rich protein. Among humans sampled by Perry et al. Sweet taste receptors in rat small intestine stimulate glucose absorption through apical GLUT2. In: Starck JM, Wang T, editors. Do dietary levels of pantothenic acid regulate its intestinal uptake in mice? Morais S, Koven W, Ronnestad I, Dinis MT, Conceicao LEC. Uldry M, Ibberson M, Hosokawa M, Thorens B. GLUT2 is a high affinity glucosamine transporter. In this region, gastric glands secrete hydrochloric acid, resulting in a low pH of 1.5 to 2.5. Culture-independent characterization of the microbiota of the ant lion Myrmeleon mobilis (Neuroptera: Myrmeleontidae). Two processes can mediate increased transporter function: recruitment of preexisting transporter protein in the cytoplasm to the membrane (as occurs for GLUT2 in response to dietary glucose, see Section Absorption of carbohydrates), and elevated gene expression. The probability of such high concordance with predictions is so infinitesimally low that the authors concluded that evolutionary changes in diet in phyllostomid bats were indeed accompanied by adaptive shifts in digestive enzymes. There are four basic types of digestive systems: monogastric, avian, rumi- nant, and pseudo-ruminant. Jongsma MA, Bolter C. The adaptation of insects to plant protease inhibitors. Lysozymes in insects: What role do they play in nitrogen metabolism? Identify structures that are a part of the digestive system, respiratory system, circulatory system, reproductive system, and excretory system. 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. 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). Antimicrobial properties of plant secondary metabolites. Sauter SN, Roffler B, Philipona C, Morel C, Rome V, Guilloteau P, Blum JW, Hammon HM. 5B), a decrease in trehalase activity, and no change in aminopeptidase activity (Fig. Mechanisms explaining differences in hydrolase activity between populations and species include gene copy number variations and single-nucleotide polymorphisms. Nitrogen cycling in the gut. Most mammals and birds have a single gene copy that codes for lysozyme. Thus, with tannins, the effects on animals are not general but depend on the particular tannin structure, concentration, and on particularities of the consumer. Erban T, Hubert J. Digestive function of lysozyme in synanthropic acaridid mites enables utilization of bacteria as a food source. Butyrate, which is a waste product of the microbial community metabolism, is the principal respiratory substrate used by the gut epithelial cells (124). The first comparison relates to sugar transport in domestic dogs and cats. As a general rule, digestive efficiency on a food type declines with increasing amount of refractory material in food. First, it keeps retention time relatively constant in the face of higher digesta flow (i.e., intake rate). Secor SM, Diamond JM. Structure-function relationships (415) and evolutionary relationships (102) among enzyme isoforms can be discerned as well. Most organic compounds absorbed across animal guts are polar, and their transport is predominantly or exclusively carrier-mediated, that is, mediated by membrane-bound transporters and displaying the twin characteristics of saturation kinetics and competitive inhibition. This is just one of the solutions for you to be successful. Bowen SH. Wright AD, Northwood KS, Obispo NE. 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. Chang MH, Chediack JG, Caviedes-Vidal E, Karasov WH. (Early reports that peptide transport is Na+-linked are erroneous.) Miller MM, Popova LB, Meleshkevitch EA, Tran PV, Boudko DY. But, also, considering the structural and functional diversity of digestive tracts among animals, it should not surprise that impacts of SMs are not necessarily general but depend on digestive features and perhaps even adaptive counterresponses of consumers. In another example, when larvae of bean weavils (Zabrotes subfasciatus) were fed seeds of Phaseolus vulgaris they secreted inducible isoforms of alpha-amylases that were insensitive to the alpha-amylase inhibitor that is found in the plant, whereas their constitutively produced alpha-amylase was inhibited by SMs in the plant [reference (29); see also references (29, 403)]. Digestive system with liver lifted to reveal gall bladder. 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). Transport across the basolateral membrane is also mediated by amino acid exchange, for example, y+L for efflux of cationic amino acids, or by facilitative diffusion, for example, transporters of the L and T system for efflux of neutral and aromatic amino acids, respectively. Ikeda I, Kobayashi M, Hamada T, Tsuda K, Goto H, Imaizumi K, Nozawa A, Sugimoto A, Kakuda T. Heat-epimerized tea catechins rich in gallocatechin gallate and catechin gallate are more effective to inhibit cholesterol absorption than tea catechins rich in epigallocatechin gallate and epicatechin gallate. Veivers PC, Musca NY, OBrien RW, Slayter M. Digestive enzymes of the salivary glands and gut of. Another flavonoid, isoquercetrin, also significantly decreased glucose absorption in rats but not in robins. Postnatal development of monosaccharide transport in pig intestine. (iii) The functional equivalent to chylomicrons in insects is the high-density lipoprotein, lipophorin, which mediates the transport of DAGs exported from enterocytes (9). [Redrawn from reference (156)], with permission. Its capacity to take up glucose from very low concentrations in the intestinal lumen is driven by the downhill gradient of Na+ ions maintained by the Na+/K+-ATPase on the basolateral membrane (Fig. Zaneveld JR, Lozupone C, Gordon JI, Knight R. Ribosomal RNA diversity predicts genome diversity in gut bacteria and their relatives. 2). They suggested that this is the reason why tubular guts predominate among complex, multicellular animals. 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. For example, in altricial house sparrows digestive biochemistry was dynamic over their 2-week period from hatching to fledging from the nest. Uptake of di- and tripeptides across the apical membrane of enterocytes is mediated by PEPT1/H+ symport, with the H+ transport coupled to the Na+/H+ antiporter NHE3. Gastrointestinal development: An overview. Some of the major classes of naturally occurring toxins in plants, such as alkaloids and phenolics (202), include many water-soluble compounds in the molecular size range that could access the paracellular space (243). Figure 19. Earlier review of scores of investigations in many taxa identified patterns that were consistent with these predictions (246). Silva CP, Terra WR, de Sa MFG, Samuels RI, Isejima EM, Bifano TD, Almeida JS. Single-nucleotide polymorphisms (SNPs) seem to explain differences among human populations in the capacity to digest lactose in milk. A metagenome analysis of fecal samples from 18 human individuals revealed a very diverse array of bacterial genes active against carbohydrates, collectively accounting for 2.6% of the sequences; the particularly high interindividual variation in the complement of glucoside hydrolase genes, even among members of the same family, was attributed to dietary factors (441). Due to the differences in the digestive systems, cattle can utilize different types of feeds than pigs. Much remains to be learned about the mechanisms that vertebrate hindgut fermenters use to take advantage of their GIT microbes. Whelan CJ, Brown JS, Schmidt KA, Steele BB, Willson MF. Shafizadeh TB, Halsted CH. The esophagus,stomach,liver . Digesta passage, digestibility and behavior in captive gorillas under two dietary regimens. Molecular-phylogenetic characterization of microbial community imbalances in human inflammatory bowel diseases. In subsequent studies, IAP-deficient (knockout) mice (190) and zebrafish (19) have been found to be hypersensitive to LPS toxicity compared with wild-type animals. Krogdahl A, Sell JL. Development of intestinal transport function in mammals. The mismatch between activity and gene expression measurements was partly explained by a nonspecific analytical method, because the whole body is analyzed (the gut of very small larvae is not isolated) and some fish tissues outside the GI tract could have lipase activity. Watanabe H, Todkuda G. Animal cellulases. Evolutionary physiology. 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). Adult rats exhibit diurnal variation in expression of sugar transporters in the intestine, with induction of GLUT2 (glucose transporter), GLUT5 (fructose transporter), and Pept-1 expression 3 to 4 h before the onset of peak feeding by the animal (100, 371, 402). But, there was more to the story because some populations (e.g., in sub-Saharan Africa and Saudi Arabia) that lacked the variant T-13910 nonetheless had a high prevalence of lactose tolerance. However, limited microbial enzymes activity does occur in the large intestine, which forms VFAs (volatile fatty acids). 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). Lysozyme is another antimicrobial enzyme found broadly across vertebrate and invertebrate taxa in many kinds of tissues including the vertebrate intestine. 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). (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. Neal JJ. Wallace RJ. Meleshkevitch EA, Robinson M, Popova LB, Miller MM, Harvey WR, Boudko DY. Prehatch intestinal maturation of turkey embryos demonstrated through gene expression patterns. Remarkably, however, nitrogen-15 labeled lysine appears in human plasma proteins hours after labeled urea is administered (168). We include a new analysis of interactions between digestive physiology and naturally occurring toxins [e.g., plant secondary metabolites (SMs)] because these biochemicals are nearly ubiquitous in foods consumed by wild animals and many of their effects are mediated through interactions with the gut. Skopec and Karasov (408) predicted that phloridzin would inhibit glucose absorption at the whole animal level when administered at ecological concentrations (they used 10 mmol/L), and that the effects would be more pronounced in nonflying mammals that rely on mediated pathway(s) for glucose absorption than birds that rely more on a nonmediated, paracellular pathway. Food then passes into the fundic region which is the first major portion of the stomach that begins the digestive process. Where sufficient information is available, phylogenetically informed analyses are included to provide better evidence of evolutionary trajectories and stronger inferences about the adaptive nature of certain traits. Fat metabolism in insects. Evolution and adaptive significance of larval midgut alkalinization in the insect superorder Mecopterida. Pancreatic amylase was also significantly correlated with dietary starch level in a phylogentically informed comparison among six passerine species that consume diets with differing amounts of starch (262). The mucosa is comprised of finger-like projection called villi, which in turn contain more micro-size projections called microvilli. In this section, two aspects of nutrient absorption are addressed: the modes of transport of the major classes of organic solutes and variation in nutrient absorption among animal taxa, in relation to nutritional habits and phylogeny and its mechanistic basis. One of the best studied chemical groups are protease or proteinase inhibitors (PIs), which bind to digestive proteins and reduce digestive efficiency and hence growth rate (237, 385). Current understanding of the matching of transporter function to diet composition derives largely from the classic work of Diamond and colleagues (120, 149) conducted on isolated intestine preparations of mice. The second example of interspecies differences in nutritional flexibility concerns two passerine birds, the house sparrow P. domesticus, which can use a range of diets including protein-rich insects and starchy seeds, and the zebra finch, Teniopygia gutta, which has a relatively fixed diet dominated by seeds. The stomach differs in structure between pigs, ruminants, and poultry. Kurokawa T, Suzuki T. Development of intestinal brush border aminopeptidase in the larval Japanese flounder, Kvale A, Mangor-Jensen A, Moren M, Espe M, Hamre K. Development and characterisation of some intestinal enzymes in Atlantic cod (. Serine proteases identified from a. Martel F, Monteiro R, Calhau C. Effect of polyphenols on the intestinal and placental transport of some bioactive compounds. Getachew G, Pittroff W, Putnam DH, Dandekar A, Goyal S, DePeters EJ.
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