Structure of Carbohydrate Moiety of Asterosaponin A

Partial acid hydrolysis of asterosaponin A, a steroidal saponin, afforded two new disaccharides in addition to O-(6-deoxy-α-d-glucopyranosyl)-(l→4)-6-deoxy-d-glucose which has been characterized in the preceding paper. The formers were demonstrated as O-(6-deoxy-α-d-galactopyranosyl)-(1→4)-6-deoxy-d-glucose and O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-6-deoxy-d-galactose, respectively.

Accordingly, the structure of carbohydrate moiety being composed of two moles each of 6-deoxy-d-galactose and 6-deoxy-d-glucose, was established as O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-O-(6-deoxy-α-d-glucopyranosyl)-(l→4)-6-deoxy-d-glucose, which is attached to the steroidal aglycone through an O-acetal glycosidic linkage.     

Intracellular Lipase Formation by Washed Mycelium Biochemical Studies on Sclerotinia Libertiana. Part 13

Intracellular lipase of the fungus Sclerotina Libertiana Fcl. could be formed powerfully by washed mycelium during shaking in a plain buffer solution, just as well as in the case of shaking culture. Experiments showed revealed it to be favourable to set the mycelium in the experiment harvested at the end of its stationary phase of growth, and that the addition of various respiratory carbon sources had inhibiting effects, while several surface active agents and some enzyme preparations accelerating effects on the lipase formation. Also, the quality and the quantity of consumed cell-materials in the shaking experiment were investigated in relation to lipase formation.     

Mode of Action of the Phospholipase from Sclerotinia Fungus

By using the purified phospholipase A and B of Sclerotinia Libertiana Fcl., enzymic degradation of soy-lecithin was investigated. From the paperchromatography experiments, it was concluded that the phospholipase A specifically hydrolyzes the ester linkage of unsaturated fatty acid of soy-lecithin whereas the phospholipase B hydrolyzes the linkage of saturated acid of soy-lysolecithin. Phospholipase B also could hydrolyze the two fatty acids from the soy-lecithin, however, the hydrolysis rate was rather inhibited by combination with the phospholipase A. Moreover, the phospholipase B activity on soy-lecithin and soy-lysolecithin was found to be increased by the presence of soy-lecithin and soy-lysolecithin in the reaction mixture, and to be inhibited by the addition of Tween 20.     

On the Molecular Weight of Polypeptide Chain of Sweet Potato β-Amylase

A number of N-acyl-L-proline derivatives were synthesized and their biological activities were investigated by using lettuce (Lactuca sativa L. cv. Sacramento) seedling test. A wide variety of these compounds promoted root growth at 25°C both under light and in darkness. Of the compounds tested, N-(2-ftuorobenzoyl)-L-proline methyl ester (4) showed the highest activity and caused a 270% increase in the root elongation compared to the control. N-(2-Naphthoyl)-L-proline methyl ester (14) promoted the root growth, while N-(1-naphthoyl)-L-proline methyl ester inhibited it. L-Proline, benzoic acid, and 2-naphthoic acid had no significant effect on lettuce seedlings. Compounds 4 and 14, and N-(2-chlorobenzoyl)-L-proline methyl ester (7) reduced the inhibitory effect of 1 ppm ABA on the root growth, while the D-isomer of 4 was less activite than compound 4. Compounds 4, 7, and 14 did not show any rescue-activity for the complete inhibition of germination that was caused by treating 10 ppm of ABA.     

Volatile Components of Roasted Almonds: Basic Fraction

Roasted almond volatiles were isolated by vacuum carbon dioxide distillation of acetone extracts and separated into basic and non-basic fractions. The basic fraction was analyzed by combination gas chromatography-mass spectrometry utilizing open tubular column. Seventeen pyrazines and 2-formyl pyrrole were identified by comparison of their mass spectra with reference spectra. Besides them, five compounds were tentatively identified by mass spectrometry.     

Circadian Locomotor Rhythms in Mice with Targeted Disruption of the Gene for the Carbon Monoxide Synthesizing Enzyme,Heme Oxygenase-2

Carbon monoxide (CO), generated in neurons by the enzyme heme oxygenase-2 (HO2), is postulated to be a gaseous signaling molecule in the mammalian brain. Because of the recent evidence suggesting an important role of another endogenously produced gas, nitric oxide (NO), in entrainment of circadian rhythms in mammals, we hypothesized that CO may also be involved in regulating these rhythms. Consistent with this idea, others have found a circadian rhythm of heme turnover and CO synthesis can be induced by bright light. Furthermore, HO2 is co-localized with guanylyl cyclase, the putative target of CO, throughout the brain, with high amounts of staining in the suprachiasmatic nucleus (SCN) of the hypothalamus. The goal of the present study was to evaluate the role of CO in photic entrainment in wild-type and HO2 deficient mice. HO2–/– mice did not display any abnormalities in circadian rhythmicity. Entrainment to a light–dark cycle, the ability to phase delay locomotor activity after a four hour phase shift in photoperiod, and the period of the free running rhythm (t) were similar between HO2–/– and wild-type mice. Taken together, these data suggest that CO does not play a major role in regulating circadian activity rhythms in mice.     

An Archaeal Homolog of Proteasome Assembly Factor Functions as a Proteasome Activator

Assembly of the eukaryotic 20S proteasome is an ordered process involving several proteins operating as proteasome assembly factors including PAC1-PAC2 but archaeal 20S proteasome subunits can spontaneously assemble into an active cylindrical architecture. Recent bioinformatic analysis identified archaeal PAC1-PAC2 homologs PbaA and PbaB. However, it remains unclear whether such assembly factor-like proteins play an indispensable role in orchestration of proteasome subunits in archaea. We revealed that PbaB forms a homotetramer and exerts a dual function as an ATP-independent proteasome activator and a molecular chaperone through its tentacle-like C-terminal segments. Our findings provide insights into molecular evolution relationships between proteasome activators and assembly factors.     

The Role of L-DOPA on Melanization and Mycelial Production in Malassezia Furfur

Melanins are synthesized by organisms of all biological kingdoms and comprise a heterogeneous class of natural pigments. Certain of these polymers have been implicated in the pathogenesis of several important human fungal pathogens. This study investigated whether the fungal skin pathogen Malassezia furfur produces melanin or melanin-like compounds. A melanin-binding monoclonal antibody (MAb) labelled in vitro cultivated yeast cells of M. furfur. In addition, melanization of Malassezia yeasts and hyphae was detected by anti-melanin MAb in scrapings from patients with pityriasis versicolor. Treatment of Malassezia yeasts with proteolytic enzymes, denaturant and concentrated hot acid yielded dark particles and electron spin resonance spectroscopy revealed that these particles contained a stable free radical compound, consistent with their identification as melanins. Malassezia yeasts required phenolic compounds, such as L-DOPA, in order to synthesize melanin. L-DOPA also triggered hyphal formation in vitro when combined with kojic acid, a tyrosinase inhibitor, in a dose-dependent manner. In this respect, L-DOPA is thought to be an essential substance that is linked to both melanization and yeast-mycelial transformation in M. furfur. In summary, M. furfur can produce melanin or melanin-like compounds in vitro and in vivo, and the DOPA melanin pathway is involved in cell wall melanization.     

IL-25, IL-33 and TSLP receptor are not critical for development of experimental murine malaria

IL-25, IL-33 and TSLP, which are produced predominantly by epithelial cells, can induce production of Th2-type cytokines such as IL-4, IL-5 and/or IL-13 by various types of cells, suggesting their involvement in induction of Th2-type cytokine-associated immune responses. It is known that Th2-type cytokines contribute to host defense against malaria parasite infection in mice. However, the roles of IL-25, IL-33 and TSLP in malaria parasite infection remain unclear. Thus, to elucidate this, we infected wild-type, IL-25^?/?, IL-33^?/? and TSLP receptor (TSLPR)^?/? mice with Plasmodium berghei (P. berghei) ANKA, a murine malaria strain. The expression levels of IL-25, IL-33 and TSLP mRNA were changed in the brain, liver, lung and spleen of wild-type mice after infection, suggesting that these cytokines are involved in host defense against P. berghei ANKA. However, the incidence of parasitemia and survival in the mutant mice were comparable to in the wild-type mice. These findings indicate that IL-25, IL-33 and TSLP are not critical for host defense against P. berghei ANKA.