Densification of cyanobacteria from a lake leading to production of β‐cyclocitral and related volatile organic compounds and species change

The purpose of the present study was to demonstrate that the lysis with the blue color formation was caused by densification of the cyanobacteria, and related events of the species change in the cyanobacteria were induced by the resulting volatile organic compounds (VOCs), particularly β‐cyclocitral. In order to obtain a high cell density of cyanobacteria in the laboratory, a concentration technique (graduated cylinder method) using the buoyancy of the gas vesicles was successfully used. The collected scum contained mainly Dolichospermum spp. and Microcystis, and the dispersed cyanobacteria were concentrated in the surface layer after several hours and the concentration ratio became approximately 10. The concentrated cyanobacteria were gradually lysed, while some of the cyanobacteria sank to the bottom, which finally died and disappeared. This method has the additional advantage that it is possible to visualize the entire lysis process. During the concentration process, β‐cyclocitral and its oxidation products together with β‐ionone were significantly detected. Because β‐cyclocitral was easily oxidized to the corresponding carboxylic acid, the pH of the water in the graduated cylinder decreased to approximately 6. Under favorable conditions, lysis with the blue color from phycocyanin could be observed due to the acid stress. Overall, the results of the present study were consistent with the hypothesis that VOCs were produced when the cyanobacteria are highly dense, and that the lysis with the blue color formation occurs due to the higher density.     

Oxidatively Damaged Erythrocytes Are Recognized by Membrane Proteins of Macrophages

Human erythrocytes incubated with an iron catalyst ADP-chelated Fe³⁺ undergo oxidative damage of the membrane including lipid peroxidation, protein oxidation, and protein aggregation, and become susceptible to recognition by human macrophages. In order to clarify the membrane components of macrophages responsible for the recogrution of the oxidized erythrocytes, binding of the oxidized cells to dot and Western blots of solubilized membrane of macrophages was investigated. The oxidized erythrocytes but not unoxidized cells bound to the dot blots. The binding was effectively inhibited by saccharide chains of band 3, a major glycoprotein of human erythrocytes, and lowered when the saccharide chains of band 3 were removed from the cell surface by pretreatment of the cells with endo-P-galactosidase which specifically cleaves the polylactosaminyl saccharide chains of band 3. The oxidized erythrocytes bound to the membrane proteins of macrophages with molecular mass of about 50, 80, and 120 kDa on Western blots depending on the saccharide chains of band 3 on their surface. The results suggest that the oxidatively damaged erythrocytes are specifically recognized by these proteins of macrophage membrane having saccharide binding ability.     

Effect of bleeding on lipid oxidation in the chub mackerel muscle

Chub mackerel samples were prepared by two different methods of killing, struggling death in iced sea water (control) and instant death by mechanical bleeding (bleeding). The malonaldehyde content in the muscles of the bleeding sample were significantly higher than those of the control after 119 h of storage at 0 degrees C.     

Involvement of asymmetric dimethylarginine (ADMA) in glomerular capillary loss and sclerosis in a rat model of chronic kidney disease (CKD)

AimsAsymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, has been reported to be a novel marker for the progression of chronic kidney disease (CKD). We have recently found that accumulation of ADMA could trigger peritubular capillary loss, thus contributing to tubulointerstitial ischemia and fibrosis in a rat model of CKD. However, effects of ADMA on glomerular capillary loss and sclerosis remain to be elucidated.Main methodsIn this study, we investigated whether lowering of ADMA by overexpression of dimethylarginine dimethylaminohydrolase (DDAH), a main enzyme that degrades ADMA, could ameliorate glomerular capillary loss and sclerosis in a rat model of CKD. Four weeks after 5/6 subtotal nephrectomy (Nx), animals were given tail vein injections with recombinant adenovirus vector encoding DDAH-I (Adv-DDAH) or control vector expressing bacterial β-galactosidase (Adv-LZ), or orally administered with 20 mg/kg/day of hydralazine (Hyz) which served as a blood pressure control model.Key findingsPlasma levels of ADMA were associated with decreased number of glomerular capillaries as well as severity of glomerular sclerosis in Nx-rats. These glomerular changes progressed in Adv-LZ- or Hyz-treated Nx-rats, while they were ameliorated by the treatment with DDAH overexpression.SignificanceOur present data suggest that ADMA may be involved in glomerular capillary loss and sclerosis, thus contributing to the progression of CKD. Substitution of DDAH protein or enhancement of its activity may become a novel therapeutic strategy for the treatment of CKD.     

C5a controls TLR-induced IL-10 and IL-12 production independent of phosphoinositide 3-kinase

The complement system is a classic central player in innate immunity. Most pathogens activate both complement and the toll-like receptor (TLR) pathway. Therefore, to provide a more comprehensive understanding of innate immunity, it is important to understand the crosstalk between these two systems. Mouse macrophages produce IL-12 and IL-10 in response to TLR ligands such as LPS, CpG, Poly I:C and Malp2. The TLR-induced IL-12 production was decreased, while that of IL-10 was increased by concurrent stimulation with a complement fragment C5a. Pharmacological studies have suggested that C5a regulates TLR4-induced IL-12 production in a phosphoinositide 3-kinase (PI3K)-dependent mechanism. In the present study, however, we found that the C5a-mediated changes can be observed in macrophages from mice lacking PI3K p85α or PI3K p110γ. The result indicates that the C5a action is PI3K-independent; neither class IA nor class IB PI3K subtype is involved in this regulation. The actions of C5a were sensitive to pertussis toxin and PD98059, suggesting a role of G protein-mediated activation of the Erk1/2 pathway.