Effect of 1,25-dihydroxyvitamin D3 on pancreatic B and D cell function

To investigate the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on pancreatic B and D cell function in normal rats, 1 microgram of 1,25(OH)2D3 was administered intravenously 20 hours before the experiment. The plasma 1,25(OH)2D3 and calcium concentrations were significantly elevated, and plasma insulin levels also increased in 1,25(OH)2D3-administered rats compared with controls. Glucose-induced insulin and somatostatin release from the isolated pancreas perfused with lower calcium, however, was the same between the 1,25(OH)2D3-administered group and the controls. On the other hand, when the isolated pancreas was perfused with higher calcium, the glucose-induced insulin release was significantly increased in the 1,25(OH)2D3-administered group, while no significant difference in somatostatin release was observed in any group. These results suggest that the sensitivity of pancreatic B cells to glucose perfused with more calcium may increase when 1,25(OH)2D3 has been previously administered. In addition, 1,25(OH)2D3 does not seem to affect the somatostatin release from the pancreatic D cells.     

Isolation and Characterization of Globulin from Seeds of Amaranthus hypochondriacus L.

Seeds of grain amaranths contain a high amount (about 60% of total nitrogen) of albumin and globulin and a trace amount of prolamin. From salt-soluble extracts of A. hypochondriacus seeds, a globulin (440,000 in apparent molecular weight and ) was purified by Sepharose 6B gel and DEAE-cellulose column chromatographies. The protein comprised at least four kinds of subunits whose molecular weights were 36,000, 32,000, 20,000 and 18,000, respectively. The amino acid composition of the globulin was almost similar to those of soybean and oat globulins.     

First report on OH-PAHs in South African Clarias gariepinus bile from an urban impacted system

The concentrations of selected hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) were determined in the bile of the African sharptooth catfish Clarias gariepinus from impoundments in the urban impacted Klip River system in Soweto, South Africa. Fish were sampled from three impoundments (Lenasia, Fleurhof, and Orlando dams) during the early high-flow season (September/October) of 2013. Biliary OH-PAHs were analysed using a high-pressure liquid chromatograph coupled to a tandem mass spectrometer (HPLC-MS/MS). Seven of the thirteen targeted metabolites were present in the fish of Soweto. The ΣOH-PAHs ranged between 0.1 and 1 876 ng ml^?1, with greatest ΣOH-PAH mean at Orlando (947 ng ml^?1) followed by Fleurhof (371 ng ml^?1). The most dominant metabolite in the sampling area was 2–,3–OH fluorene, ranging between not detected and 1 429 ng ml^?1, with the greatest mean at Orlando (709 ng ml^?1). PAH metabolites quantified in C. gariepinus most likely originated from the sediments. The hepatosomatic index of the C. gariepinus increased proportionally with the biliary OH-PAH concentrations. To the authors’ knowledge this data on biliary OH-PAH for fish is the first for South Africa.     

Complete Nucleotide Sequence of the Mouse Lactate Dehydrogenase-a Functional Gene: Comparison of the Exon-Intron Organization of Dehydrogenase Genes

The complete sequence of 12,851 nucleotides of the mouse lactate dehydrogenase-A (LDH-A) gene has been determined. It includes eight exons, seven introns, promoter and regulatory regions. The B1 repetitive elements present in intron III and VI are oriented in opposite orientation, and they share 72% sequence homology. The exon-intron organization of mouse LDH-A gene is compared with the organizations of other dehydrogenase genes, and the molecular evolution of the nicotinamide adenine dinucleotide binding domains is discussed.     

Isolation and Characterization of a Fucoidan-Degrading Marine Bacterium

Fucoidan, a mixture of sulfated fucose-containing polysaccharides, was prepared from the algal bodies of Cladosiphon okamuranus (class Phaeophyceae, order Chordariales, family Chordariaceae) with a yield of 2.0% of the wet weight of the alga. To obtain enzymes that digest the fucoidan, we screened bacteria in the gut contents of the sea cucumber Stichopus japonicus for their ability to decrease the fucoidan in their culture media, and successfully isolated one bacterial strain that could decrease it. The bacterial strain was gram-negative and possessed menaquinone 7 as the predominant respiratory quinone, and the GC content of its genomic DNA was 52%. The results of the phylogenetic analysis of its 16S ribosomal DNA sequence indicated that the bacterial strain was a member of the division Verrucomicrobia. However, as the bacterial strain is phylogenetically and phenotypically distinct from verrucomicrobial species described previously, the strain was assumed to be a new member of the division Verrucomicrobia. When the bacterial strain was cultivated in an algal fucoidan-containing medium, the strain decreased fucoidan from C. okamuranus (44%), Nemacystus decipiens (19%), Laminaria japonica (31%), Kjellmaniella crassifolia (23%), sporophyl of Undaria pinnatifida (22%), Fucus vesiculosus (42%), and Ascophyllum nodosum (61%).     

Cold-induced activation of brown adipose tissue and adipose angiogenesis in mice

Exposure of humans and rodents to cold activates thermogenic activity in brown adipose tissue (BAT). This protocol describes a mouse model to study the activation of BAT and angiogenesis in adipose tissues by cold acclimation. After a 1-week exposure to 4 °C, adult C57BL/6 mice show an obvious transition from subcutaneous white adipose tissue (WAT) into brown-like adipose tissue (BRITE). The BRITE phenotype persists after continuous cold exposure, and by the end of week 5 BRITE contains a high number of uncoupling protein-1-positive mitochondria, a characteristic feature of BAT. During the transition from WAT into BRITE, the vascular density is markedly increased owing to the activation of angiogenesis. In BAT, cold exposure stimulates thermogenesis by increasing the mitochondrial content and metabolic rate. BAT and the increased metabolic rate result in a lean phenotype. This protocol provides an outstanding opportunity to study the molecular mechanisms that control adipose mass.     

Aminoglycoside antibiotics reduce glucose reabsorption in kidney through down-regulation of SGLT1

Nephrotoxicity is known to be a major clinical side effect of aminoglycoside antibiotics. Aminoglycosides cause damage to proximal tubular cells in kidney, however the mechanism of toxicity is still unclear. In order to elucidate the mechanism of nephrotoxicity, we studied the effect of aminoglycoside antibiotics on glucose transport systems in vitro and in vivo. As a result, we found that the aminoglycosides significantly reduced Na(+)/glucose cotransporter (SGLT1)-dependent glucose transport and also down-regulated mRNA and protein levels of the SGLT1 in pig proximal tubular LLC-PK(1) cells. To obtain evidence about SGLT1 down-regulation in vivo, we studied the mRNA expression of SGLT1 using gentamicin C-treated murine kidney and found that gentamicin C down-regulated SGLT1 in vivo as well as in vitro. Furthermore, the gentamicin C-treated mice showed significant rise in urinary glucose excretion. These results indicate that one of the mechanisms of aminoglycoside nephrotoxicity is the down-regulation of SGLT1, which causes reduction in glucose reabsorption in kidney.     

A change in the sensitivity of elongation factor G to oxidation protects photosystem II from photoinhibition in Synechocystis sp. PCC 6803

The repair of photosystem II (PSII) after photodamage is particularly sensitive to oxidative stress and inhibition of such repair is associated with the oxidation of specific cysteine residues in elongation factor G (EF-G), a key translation factor, in the cyanobacterium Synechocystis sp. PCC 6803. Expression of mutated EF-G with a target cysteine residue replaced by serine in Synechocystis resulted in the protection of PSII from photoinhibition. This protection was attributable to the enhanced repair of PSII via acceleration of the synthesis of the D1 protein, which might have been due to reduced sensitivity of protein synthesis to oxidative stress.