A phylogenetic survey of biliary lipids in vertebrates ,

Abstract

Biliary lipids (bile salts, phospholipids, cholesterol, plant sterols) were determined in 89 vertebrate species (cartilaginous and bony fish, reptiles, birds, and mammals), and individual phospholipid classes were measured in 35 species. All samples contained conjugated bile salts (C 27 bile alcohol sulfates and/or N -acyl amidates of C 27 and/or C 24 bile acids). Phospholipids were generally absent in the bile of cartilaginous fish and reptiles and were present in low amounts relative to bile salts in bony fish and most birds. In mammals, the phospholipid-bile salt ratio varied widely. The bile from species with low biliary phospholipid-bile salt ratios often contained a high proportion of sphingomyelin, confirmed by HPLC-MS. In species with a high phospholipid-bile salt ratio, the predominant biliary phospholipid was phosphatidylcholine (PC). The phospholipid-bile salt ratio correlated weakly with the calculated weighted hydrophobic index value. Cholesterol was present in the bile of virtually all species, with plant sterols uniformly being present in only trace amounts. The cholesterol-bile salt ratio tended to be higher in mammals than in nonmammals, but bile of all species was unsaturated. Thus, most nonmammalian vertebrates have relatively low levels of biliary phospholipid and cholesterol, suggesting that cholesterol is eliminated predominantly as bile salts. Mammals have a higher phospholipid and cholesterol to bile salt ratio, with the dominant phospholipid being

The Gallbladder ofUranoscopus ScaberL. (Teleost Perciform Fish) is Lined by Specialized Cholecystocytes

“…The fatty acid levels in the blood are relatively low while the diet is lipid-rich (Plisetskaya, 1980), and, probably as in other Perciforms, the main bile components are phospholipids, cholic, and chenodeoxycholic acids along with 5b-bile alcohols (Moschetta et al, 2005;Hagey et al, 2010). Cholesterol nuclei could develop more easily from bile and cholecystocyte transport, because phospholipids appear generally absent in the bile of bony fish and most birds, while in mammals, the phospholipid to bile ratio varies widely among species.…”

Atp8b1 deficiency in mice reduces resistance of the canalicular membrane to hydrophobic bile salts and impairs bile salt transport

“…Mouse bile contains predominantly trihydroxy bile salts (cholate and muricholate), whereas in human bile, the majority of bile salts is dihydroxy bile salts, which are much more hydrophobic. 46,47 These differences underscore the importance of bile salt pool composition in the cause of PFIC1, and also may explain the beneficial effects of bile drainage in PFIC patients. 48,49 This procedure interrupts the enterohepatic circulation and causes a shift of the bile salt composition toward primary, more hydrophilic bile salts.…”

Ligand specificity and evolution of liver X receptors

“…The bile salts of non-mammalian vertebrates can differ from that of the 24-carbon (C 24 ) bile acids found in the majority of mammals [26,27]. For example, the 27-carbon (C 27 ) bile alcohol 5α-cyprinol (5α-cholestan-3α,7α,12α,26,27-pentol) 27-sulfate is known to be the dominant constituent of zebrafish bile [28].…”