Anti-oxidation activity of ethanol extracts from natural thalli of lichens

Screening test on anti-oxidation activity using 1,1-diphenyl-2-picrylhydrazyl(DPPH) was performed for 99 ethanol extracts of 85 species of natural thalli of lichens in order to find novel anti-oxidation compounds.The 17 extracts of natural thalli showed high anti-oxidation activity.Among them,the activities of extracts from Hypogymnia vittata,Peltigera aphthosa,Nephromopsis ornata,Pseudevernia furfuracea,Cladonia vulcani and Peltigera elizabethae were higher.Extracts of Peltigera spp.showed higher activity than those of other genera.The ethanol extract of P.aphthosa had been separated into ethyl acetate-soluble and water-soluble fractions.Two anti-oxidative spots were found only in the water-soluble fractions by thin-layer chromatography.The compound in the lower spot had the same Rf value,UV spectrum,and color as authentic solorinine that was previously found as a unique quaternary ammonium compound from Peltigera spp.We now report that the hydrophilic lichen substance,solorinine showed a nearly same anti-oxidation activity(EC50=120?mol/Lol/L) as standard antioxidant Trolox(EC50=150?mol/L).     

Genetic Regulation of Melanocyte Differentiation

Melanocytes originate from the neural crest in vertebrates and migrate to the body surface where they differentiate into functional cells. Genes involved in melanocyte differentiation can be classified into two groups. One of them consists of the functional genes that control proteins specific to the function of the melanocyte. As the representative gene of this category, albino (c) locus in the mouse is considered to control tyrosinase, the key enzyme in melanogenesis. cDNA for mouse tyrosinase has been cloned and sequenced. The cDNA can be used to detect tyrosinase mRNA synthesized during melanocyte differentiation. On the other hand, genes such as brown (b) or pink-eyed dilution (p) have been assumed to control melanosome proteins. The other category consists of genes that regulate the expression of these functional genes directly or indirectly. In the mouse, so-called white-spotting genes and genes of the agouti series are considered to fall into this category. Based on the fact that mutations at the white-spotting loci result in the absence of melanocytes in a particular area of skin, it is assumed that some of these loci control the factors that promote either differentiation or migration of melanoblasts and are candidates for the classic regulator genes Genes at the agouti (a) locus in the mouse determine the type of melanin synthesized in hair follicle melanocytes, that is eumelanin or pheomelanin. An interesting feature of this locus is that the site of gene action is not within the melanocytes but in the cells surrounding them. The results of our study indicate that the gene product of the a-locus interacts with α-MSH at the α-MSH receptor site, regulates the cellular cAMP level via a signal transduction system and, in turn, determines the type of melanin synthesized in the cells.     

Fate and Transport of High Explosives in a Sandy Soil: Adsorption and Desorption

Several areas of the Massachusetts Military Reservation (MMR) have soils with significant levels of high explosives (HE) contamination because of a long history of training and range activities (such as open burning, open detonation, disposal, and artillery and mortar firing). Site-specific transport and attenuation mechanisms were assessed in sandy soils for three contaminants of concern: the nitramine hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and the nitroaromatics 2,4-dinitrotolune (2,4-DNT) and 2,4,6-trinitrotoluene (TNT). For all three contaminants, linear distribution coefficients (K_d) were dependent on the fraction of organic carbon in soil. The nitroaromatics sorbed much more strongly than RDX in both soils. Over 120 hours, the desorption rate of RDX from field contaminated surface soil was much slower than its sorption rate, with the desorption K_d (1.5 L/kg) much higher than K_d for sorption (0.37 L/kg). Desorption of 2,4-DNT was negligible over 120 hours. Thus, applying sorption-derived K_d values for transport modeling may significantly overestimate the flux of explosives from MMR soils. Based on multiple component column transport tests, RDX will be the most mobile of these contaminants in MMR soils. In saturated columns packed with uncontaminated soil, RDX broke through rapidly, whereas the nitroaromatics were significantly attenuated by irreversible sorption or abiotic transformations.     

The lack of chiral specificity in a termite queen pheromone

The queens of many social insects produce pheromones that influence the behaviour and physiology of colony members. Pheromones produced by queens have long been considered as the prime factor inhibiting the differentiation of new reproductive individuals. A volatile pheromone consisting of a blend of n‐butyl‐n‐butyrate and 2‐methyl‐1‐butanol comprises a queen pheromone that inhibits the differentiation of female neotenic reproductives (secondary queens) of a termite Reticulitermes speratus. 2‐Methyl‐1‐butanol is the first chiral molecule to be identified as a primer pheromone in social insects, which presents the intriguing question of whether enantiomeric composition plays a role in caste regulation. In the present study, we report that the (R)‐ and (S)‐enantiomers and the racemic mixture of 2‐methyl‐1‐butanol show significant inhibitory effects on the differentiation of new female neotenics in combination with n‐butyl‐n‐butyrate, whereas no significant difference in inhibitory activity is observed among them. These results suggests that termites recognize 2‐methyl‐1‐butanol as a queen signal but they do not distinguish between the stereostructures of the enantiomers.     

Macrophage Migration Inhibition by Serum from Desensitized Animals Previously Sensitized with Tubercle Bacilli

MIGRATION of peritoneal exudate cells removed from guinea-pigs or mice exhibiting delayed hypersensitivity is inhibited by specific antigen^1–3. This in vitro macrophage migration inhibition has been regarded as a useful immunological test for delayed skin hypersensitivity^4,5. Studies of the mechanism of this phenomenon revealed that, in contact with specific antigen, lymphocytes from sensitized animals released into the medium a specific substance (migration inhibitory factor; MIF) capable of inhibiting the migration of normal macrophages^6,7. When injected intradermally into normal guinea-pigs, MIF elicits inflammatory reactions characterized by induration, erythema and mononuclear cell infiltration⁸.