Comprehensive analysis of genes contributing to euryhalinity in the bull shark, Carcharhinus leucas; Na+-Cl- co-transporter is one of the key renal factors upregulated in acclimation to low-salinity environment.

Most cartilaginous fishes live principally in seawater (SW) environments, but a limited number of species including the bull shark, Carcharhinus leucas, inhabit both SW and freshwater (FW) environments during their life cycle. Euryhaline elasmobranchs maintain high internal urea and ion levels even in FW environments, but little is known about the osmoregulatory mechanisms that enable them to maintain internal homeostasis in hypoosmotic environments. In the present study, we focused on the kidney because this is the only organ that can excrete excess water from the body in a hypoosmotic environment. We conducted a transfer experiment of bull sharks from SW to FW and performed differential gene expression analysis between the two conditions using RNA-sequencing. A search for genes upregulated in the FW-acclimated bull shark kidney indicated that the expression of the Na+-Cl- cotransporter (NCC; Slc12a3) was 10 times higher in the FW-acclimated sharks compared with that in SW sharks. In the kidney, apically located NCC was observed in the late distal tubule and in the anterior half of the collecting tubule, where basolateral Na+/K+-ATPase was also expressed, implying that these segments contribute to NaCl reabsorption from the filtrate for diluting the urine. This expression pattern was not observed in the houndshark, Triakis scyllium, which had been transferred to 30% SW; this species cannot survive in FW environments. The salinity transfer experiment combined with a comprehensive gene screening approach demonstrates that NCC is a key renal protein that contributes to the remarkable euryhaline ability of the bull shark.

3D-TEM study on the novel bicontinuous microdomain structure.

An ordered bicontinuous double-diamond (OBDD) morphology was found in polystyrene-block-(poly-4-vinylphenyldimethylvinylsilane-graft-polyisoprene), PS-b-(PVS-g-PI), block-graft copolymer. We obtained a 3D image of the microdomain structure formed in PS-b-(PVS-g-PI) using 3D-TEM. The 3D image shows that the polystyrene (PS) phase consists of two independent and interwoven networks. The structures of the two networks are identical and include tetrapod units that form planar six-membered rings. The features of the networks agree with those in the OBDD morphology, indicating that PS-b-(PVS-g-PI) exhibits ordered three-dimensional OBDD networks with the PS phase in the polyisoprene (PI) matrix phase. The grafted PI chains induce the frustration of the PS chains; thus, the effects of the specific interface are more dominant than those of packing frustration in the formation of the morphology, and the OBDD phase is stabilized.

Benzofuran derivatives inhibit 11ß-hydroxysteroid dehydrogenase type 1 activity in rat adipose tissue.

Excess glucocorticoids promote visceral obesity and insulin resistance. The main regulator of intracellular glucocorticoid levels are 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1), which converts inactive glucocorticoid into bioactive glucocorticoid such as cortisol in humans and corticosterone in rodents; therefore, the inhibition of 11ß-HSD1 has considerable therapeutic potential for metabolic diseases including obesity and diabetes. Benzofuran is a key structure in many biologically active compounds such as benzbromarone, malibatol A and (+)-liphagal. The aim of this study was to investigate the inhibitory effect of benzofuran derivatives on 11ß-HSD1 in mesenteric adipose tissue from rodents. 11ß-HSD1 activity was determined by incubation of rat mesenteric adipose tissue microsomes in the presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH) with and without benzofuran derivatives (Compounds 1-14). The corticosterone produced was measured by HPLC. More than 40% of 11ß-HSD1 inhibition was observed in Compounds 1, 5, 7 and 8. Moreover, Compounds 7 and 8 inhibited the 11ß-HSD1 activity in adipose microsomes dose- and time-dependently, as well as in 3T3-L1 adipocytes. Compounds 7 and 8 did not inhibit 11ß-HSD type 2 (11ß-HSD2), whereas Compounds 1 and 5 inhibited 11ß-HSD2 by 18.7% and 56.3%, respectively. Further, a kinetic study revealed that Compounds 7 and 8 acted as non-competitive inhibitors of 11ß-HSD1. Ki (nmol/h/mg protein) values of Compounds 7 and 8 were 17.5 and 24.0, respectively, with IC50 (µM) of 10.2 and 25.6, respectively. These data indicate that Compounds 7 and 8 are convincing candidates for seed compounds as specific inhibitors of 11ß-HSD1 and have the potential to be developed as anti-obesity drugs.

17Beta-estradiol inhibits 11beta-hydroxysteroid dehydrogenase type 1 activity in rodent adipocytes.

17Beta-estradiol (E(2)) serves as an anti-obesity steroid; however, the mechanism underlying this effect has not been fully clarified. The effect of E(2) on adipocytes opposes that of glucocorticoids, which potentiate adipogenesis and anabolic lipid metabolism. The key to the intracellular activation of glucocorticoid in adipocytes is 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), which catalyses the production of active glucocorticoids (cortisol in humans and corticosterone in rodents) from inactive 11-keto steroids (cortisone in humans and 11-dehydrocorticosterone in rodents). Using differentiated 3T3-L1 adipocytes, we showed that E(2) inhibited 11beta-HSD1 activity. Estrogen receptor (ER) antagonists, ICI-182 780 and tamoxifen, failed to reverse this inhibition. A significant inhibitory effect of E(2) on 11beta-HSD1 activity was observed within 5-10 min. Furthermore, acetylation or alpha-epimerization of 17-hydroxy group of E(2) attenuated the inhibitory effect on 11beta-HSD1. These results indicate that the inhibition of 11beta-HSD1 by E(2) depends on neither an ER-dependent route, transcriptional pathway nor non-specific fashion. Hexose-6-phosphate dehydrogenase, which provides the cofactor NADPH for full activation of 11beta-HSD1, was unaffected by E(2). A kinetic study revealed that E(2) acted as a non-competitive inhibitor of 11beta-HSD1. The inhibitory effect of E(2) on 11beta-HSD1 was reproduced in adipocytes isolated from rat mesenteric fat depots. This is the first demonstration that E(2) inhibits 11beta-HSD1, thereby providing a novel insight into the anti-obesity mechanism of estrogen.