(2)]. Infante JLZ, Cahu CL. Subsequently, other SNPs were identified that correlated with lactose tolerance, and analyses seem to indicate that convergent evolution of the phenotype occurred a number of times at different locations (138). A monogastric digestive system has one simple stomach. The first section is the duodenum. Nedergaard S. Amino acid transport. Development of intestinal transport function in mammals. Davis HR, Jr, Zhu LJ, Hoos LM, Tetzloff G, Maguire M, Liu J, Yao X, Iyer SP, Lam MH, Lund EG, Detmers PA, Graziano MP, Altmann SW. Niemann-Pick C1 Like 1 (NPC1L1) is the intestinal phytosterol and cholesterol transporter and a key modulator of whole-body cholesterol homeostasis. Phylogenetic analysis assigns the mammalian GLUT2 to a clade that includes three further mammalian GLUTs (GLUT1, 3, and 4) and invertebrate, but no nonmetazoan, GLUTs, suggesting that this group of transporters may have evolved in the basal metazoans or immediate ancestors of animals (472). The species richness of the microbiota in the GI tract of many invertebrate animals is apparently an order of magnitude lower than in mammals, commonly with just 10 to 20 taxa per individual (7, 22, 123, 131, 285, 381, 475). The short-chain fatty acids (SCFAs; also called volatile fatty acids), such as acetic, propionic, and butyric acid, that are generated during fermentation can be absorbed in many regions of the gut by transcellular nonionic diffusion when they are protonated [(246); see also Section Transcellular pathways for lipid absorption). A pig weighing around 60 kilograms will, for example, resemble a human body in many ways, including fat distribution, cover of hair and ability to attract insects. Graf GA, Li WP, Gerard RD, Gelissen I, White A, Cohen JC, Hobbs HH. These animals mature and develop a greater appetite. Intestinal lipid absorption. The primate and ruminant digestive lysozyme evolved from a conventional lysozyme, whereas that in the hoatzin evolved from a calcium-binding lysozyme that is expressed in the egg white (248). Uptake across the apical membrane is mediated by: Na+-coupled transporters, for example, the B0 transporter with broad specificity for neutral amino acids and found in all parts of the small intestine; proton-motive force, as in the uptake of proline and glycine by the transporter PAT; and amino acid exchange, for example, uptake of cationic amino acids and cystine linked to efflux of neutral amino acids by b0,+ system. 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. Sugar absorption in the intestine: The role of GLUT2. The amino acid transporters are classified by their activity (specificity and kinetics) into multiple systems, and by sequence homology into solute carrier (SLC) families. The mechanism of chylomicron assembly is reviewed by reference (227). A competing hypothesis about the animals response is that overproduction of digestive proteins is to the detriment of other essential proteins in the body, and that growth rate thus does not recover (237). Shen L, Weber CR, Raleigh DR, Yu D, Turner JR. 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. In addition, the sodium bicarbonate serves a vital role to provide alkalinity so chyme can be transported though the small intestine without causing cell damage because of the low pH after leaving the stomach. Hindgut fermentation in three species of marine herbivorous fish. During the gestational phase, organs undergo morphological maturation [see also reference (354)] and many proteins required for digestion and absorption of components of milk are expressed (e.g., amino acid transporters and the glucose transporter SLGT1). Voght SP, Fluegel ML, Andrews LA, Pallanck LJ. Diversity of beetle genes encoding novel plant cell wall degrading enzymes. 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). Skin breakdown and blisters from senna-containing laxatives in young children. A second feature that strengthens the analysis is a larger number of species measured by uniform methodology and subjected to phylogenetically informed statistical analyses. Effects of 9,10 anthraquinone on ruminal fermentation, totaltract digestion, and blood metabolite concentrations in sheep. Gastrointestinal responses to fasting in mammals: Lessons from hibernators. Fine KD, Santa Ana CA, Porter JL, Fordtran JS. Permeability of the rat small intestine to carbohydrate probe molecules. Digestive responses during food restriction and realimentation in nestling house sparrows (. (392) used a phylogeny for New World bats (family Phyllostomidae) to analyze the correlation between diet and digestive enzymes in 14 species (Fig. Indeed, lysozyme accounts for 10% of the total gastric mucosal protein and messenger RNA in ruminants.
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