Moulting of a deep-sea galatheid crab (Anomura, Galatheidae) at a depth of 3572 m

The moulting of the deep-sea galatheid crab, Mundopsissp. was observed using a seafloor observatory at a depth of 3572 m in Nankai Trough, western Japan. The duration of the ecdysis was 147 seconds. The crab rested on the substratum until ecdysis was complete. After ecdysis, it flicked and moved away from its exuviae. The newly moulted galatheid crab did not consume its cast exoskeleton.     

Identification of genes expressed in the shoot apex ofBrassica campestris during floral transition

The vegetative-to-floral transition ofBrassica campestris cv. Osome was induced by vernalization. Poly(A)+RNA was isolated from the transition shoot apex after 6 weeks of vernalization, the floral apex after 12 weeks of vernalization and the expanded leaves just before vernalization, and cDNAs were synthesized. These cDNAs were used for subtraction and differential screening to select cDNA preferentially present in the transition and floral apices. Nucleotide sequences of the resulting 14 cDNA clones were determined, and northern blot analysis was carried out on six cDNAs. Two cDNA clones which did not show significant similarity to known genes were shown to be preferentially expressed in the floral apex.     

The enhancing action of D-galactosamine on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophage cells

The effect of D-galactosamine (D-GalN) on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells was examined. D-GalN augmented the production of NO, but not tumor necrosis factor (TNF)-alpha in LPS-stimulated RAW 264.7 cells. Pretreatment of D-GalN augmented the NO production whereas its post-treatment did not. D-GalN augmented the NO production in RAW 264.7 cells stimulated with either TNF-alpha and interferon-gamma. The augmentation of LPS-induced NO production by D-GalN was due to enhanced expressions of an inducible type of NO synthase mRNA and proteins. Intracellular reactive oxygen species (ROS) were exclusively generated in RAW 264.7 cells stimulated with D-GalN and LPS. Scavenging of intracellular ROS abrogated the augmentation of NO production. It was therefore suggested that D-GalN might augment LPS-induced NO production through the generation of intracellular ROS.     

Suppression of pacemaker activity by Ginkgo biloba extract and its main constituent, bilobalide in rat sino-atrial nodal cells

Effects of Ginkgo biloba extract (GBE) and bilobalide (a main constituent) on the pacemaker activity and the underlying ionic currents in rat sino-atrial (SA) nodal cells were investigated using patch-clamp techniques. Both GBE and bilobalide depressed the pacemaker activity in a concentration-dependent manner. At both 0.03 mg/ml GBE and 0.3 microM bilobalide, a negative chronotropic effect was produced. Dysrhythmias often occurred. The L-type Ca(2+) current (I(Ca)) and the hyperpolarization-activated inward current (I(f)) decreased by 69.7+/-3.2% (n=6, P<0.001) and by 12.6+/-2.1% (n=7, P<0.05) at 0.03 mg/ml GBE, and by 51.2+/-3.3% (n=6, P<0.01) and by 19.8+/-2.2 % (n=6, P<0.05) at 0.3 microM bilobalide, respectively. The delayed rectifier K(+) current (I(K)) also decreased. The inhibition was 12.3+/-2.0% (n=6, P<0.05) at 0.03 mg/ml GBE, and was 28.0+/-2.9% (n=6, P<0.05) at 0.3 microM bilobalide. These results indicate that cardiac ionic channels contributing to the pacemaking are highly sensitive to GBE and bilobalide, which can sufficiently modify the spontaneous activity in rat SA nodal cells.     

The response to thromboxane A2 analogues in human platelets. Discrimination of two binding sites linked to distinct effector systems

Thromboxane A2 (TXA2) induces platelet shape change, secretion, and aggregation. Using a novel TXA2/prostaglandin endoperoxide receptor antagonist, [1r-[1 alpha(Z),2 beta,3 beta,5 alpha]]-(+)-7-[5-[[(1,1'- biphenyl)-4-yl]methoxy]-3-hydroxy-2-(1-piperidinyl) cyclopentyl]-4-heptenoic acid hydrochloride (GR32191), we demonstrate that these responses are mediated by at least two receptor-effector systems. GR32191 non-competitively inhibited platelet aggregation to the TXA2 mimetics, (15S)-hydroxy-11,9-(epoxymethano) prostadienoic acid (U46619) and [1S-(1 alpha,2 beta(5Z),3 alpha (1E,-3S), 4 alpha)]-7-[3-(3-hydroxy-4-(p-iodophenoxy)-1-butenyl)7- oxabicyclo[2.2.1]hept-2yl]-5-heptenoic acid by binding irreversibly to a TXA2/prostaglandin endoperoxide receptor. Dissociation of [3H]GR32191 from human platelets demonstrated two specific binding sites, one which was rapidly dissociating and a site to which binding was essentially irreversible. Stimulation by U46619 of platelets incubated with GR32191 and subsequently washed to expose the reversible binding site failed to aggregate or to secrete [3H]5-hydroxy-tryptamine; formation of inositol phosphates and activation of protein kinase C were markedly suppressed. In contrast, platelet shape change and calcium stimulation remained at 90% of control. Furthermore, stimulation of the reversible binding site with U46619 induced aggregation in the presence of ADP, demonstrating its functional importance in amplifying the response to other agonists. These data suggest that TXA2 mediates platelet activation through at least two receptor-effector systems; one linked to phospholipase C activation, resulting in platelet aggregation and secretion and a second site mediating an increase in cytosolic calcium and platelet shape change.     

Mycolic acid-containing bacteria induce natural-product biosynthesis in Streptomyces species

Natural products produced by microorganisms are important starting compounds for drug discovery. Secondary metabolites, including antibiotics, have been isolated from different Streptomyces species. The production of these metabolites depends on the culture conditions. Therefore, the development of a new culture method can facilitate the discovery of new natural products. Here, we show that mycolic acid-containing bacteria can influence the biosynthesis of cryptic natural products in Streptomyces species. The production of red pigment by Streptomyces lividans TK23 was induced by coculture with Tsukamurella pulmonis TP-B0596, which is a mycolic acid-containing bacterium. Only living cells induced this pigment production, which was not mediated by any substances. T. pulmonis could induce natural-product synthesis in other Streptomyces strains too: it altered natural-product biosynthesis in 88.4% of the Streptomyces strains isolated from soil. The other mycolic acid-containing bacteria, Rhodococcus erythropolis and Corynebacterium glutamicum, altered biosynthesis in 87.5 and 90.2% of the Streptomyces strains, respectively. The coculture broth of T. pulmonis and Streptomyces endus S-522 contained a novel antibiotic, which we named alchivemycin A. We concluded that the mycolic acid localized in the outer cell layer of the inducer bacterium influences secondary metabolism in Streptomyces, and this activity is a result of the direct interaction between the mycolic acid-containing bacteria and Streptomyces. We used these results to develop a new coculture method, called the combined-culture method, which facilitates the screening of natural products.     

Plasma concentration of prolactin during four-day osmotic pump infusion of thyrotropin-releasing hormone and vasoactive intestinal polypeptide in rats

Pituitary prolactin (PRL) responses to 4-day continuous infusion of thyrotropin-releasing hormone (TRH) and vasoactive intestinal polypeptide (VIP) were investigated in unanesthetized male rats using Alzet osmotic minipumps. The TRH dose infused was 3.6 micrograms/day and the VIP dose was 32.8 micrograms/day. Infusion of TRH with osmotic pumps elevated the plasma PRL level compared to controls over the 4-day infusion period. However, mean levels of PRL tended to decrease during the 4-day infusion. On the other hand, continuous VIP infusion elicited a significant continuous PRL release over the 4-day infusion period. Thus, it may be said that the PRL responses to infused TRH and VIP were maintained during the 4-day infusion.