Host size- and habitat-dependent intensity of Heliconema longissimum (Nematoda: Physalopteridae) in the Japanese eel (Anguilla japonica)

Heliconema longissimum (Ortlepp, 1923) is an ecologically poorly known nematode found in the stomach of Japanese eels, Anguilla japonica Temminck and Schlegel. The occurrence of this nematode in Japanese eels was surveyed in 2 contiguous brackish-water areas (Misho Cove and the lower Renjoji River) of Ehime Prefecture, western Japan, during April 2008 to March 2009. The factors associated with the nematode intensity were also assessed by applying generalized additive models (GAM). Heliconema longissimum exhibited nearly 100% prevalence in both areas, but its intensity differed. The heavier infection in the cove eels indicates that H. longissimum is mainly distributed in the cove, which supports the past speculation for this nematode as a brackish-water parasite. The intensity also increased with the body size of eels. This tendency suggests that the eels inhabiting the cove consume, as they grow, a greater quantity of crustaceans that presumably serve as the nematode's intermediate hosts.     

Formation of sheared G:A base pairs in an RNA duplex modelled after ribozymes, as revealed by NMR.

The thermal stability and structure of an RNA duplex, r(GGACGAGUCC)2, the base sequence of which was modelled after both a hammerhead ribozyme and a lead ribozyme, were studied by CD and NMR. We previously demonstrated that the corresponding DNA duplex, d(GGACGAGTCC)2, formed unique 'sheared' G:A base pairs, where an amino proton, instead of an imino proton, of G is involved in the hydrogen bonding, and G and A bases are arranged 'side by side' instead of 'head to head' (Nucleic Acids Res. (1993) 21, 5418-5424). CD melting profiles showed that the RNA duplex is thermally more stable than the corresponding DNA duplex. NMR studies revealed that sheared G:A base pairs are formed in the RNA duplex, too, although the overall structure of the RNA is the A form, which differs from the B form taken on by the corresponding DNA. A model building study confirmed that sheared G:A base pairs can be accommodated in the double helical structure of the A form. A difference between the RNA and DNA duplexes in the stacking interaction involving G:A mismatch bases is also suggested. The demonstration that sheared G:A base pairs can be formed not only in DNA but also in RNA suggests that this base pairing plays an important role regarding the RNA structure.     

NMR Studies of a Lead Ribozyme and Its Non-Cleavable Analogue

Abstract

The structure of a lead ribozyme, which consists of two RNA strands, at neutral pH has been studied by NMR. Nearly all resonances of imino protons, base protons (H2, H5, H6 and H8) and sugar protons (H1′ and H2′) were assigned sequentially. Interesting structural features which deviate from the standard structure were found for the residues at an active site which consists of an internal loop. No indication of stable G:A base pairs was found in the loop. The effect of addition of Pb²⁺ was studied by the use of a non-cleavable analogue in which the cytidine at a cleavage site is replaced by 2′-O-methylcytidine. It was suggested that Pb²⁺ binds close to the cleavage site and that the structural change induced by Pb²⁺ is moderate and localized.

     

Structural Characterization of a DNA Duplex Modeled on a DNA:RNA Hybrid of the Polypurine Tract Recognized by a Reverse Transcriptase

Abstract

The structure of d(TTAAAAGAAAAGGG):d(CCCTTTTCTTTTAA) has been characterized by NMR. The minor grooves of the two dA-tracts are suggested to be rather narrow, and the portion linking the two dA tracts exhibits a slightly deviated structure from a standard B DNA, in order to maintain the narrowness of the minor groove. The structure of the dG-tract is also slightly deviated. Additionally, specific broadening of resonances is observed for the residues at or near the junction between the dA-tract and the dG-tract, suggesting local structural polymorphology.

     

A simple explanation for the evolution of complex song syntax in Bengalese finches

The songs of Bengalese finches (Lonchura striata var. domestica) have complex syntax and provide an opportunity to investigate how complex sequential behaviour emerges via the evolutionary process. In this study, we suggest that a simple mechanism, i.e. many-to-one mapping from internal states onto syllables, may underlie the emergence of apparent complex syllable sequences that have higher order history dependencies. We analysed the songs of Bengalese finches and of their wild ancestor, the white-rumped munia (L. striata), whose songs are more stereotypical and simpler compared with those of Bengalese finches. The many-to-one mapping mechanism sufficiently accounted for the differences in the complexity of song syllable sequences of these two strains.     

Stepwise oral immunotherapy for 10 days in an egg-white allergy mouse model did not ameliorate the severity of allergy but induced the production of allergen-specific IgA

ABSTRACT

We examined whether the stepwise oral immunotherapy (OIT) for 10 days ameliorates the severity of allergy and the biomarkers in an allergy mouse model. The OIT could not protect anaphylaxis symptoms after allergen challenges but promote the production of antibodies, especially allergen-specific IgA. It was suggested that this OIT influenced the function of immuno response against the allergen.

Abbreviations: EW: egg white; IFC: intraperitoneal food challenge; IFN-γ: interferon-γ; IL: interleukin; OVA: ovalbumin; OM: ovomucoid; OFC: oral food challenge; OIT: oral immunotherapy.     

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE2 secretion from macrophages

The purpose of this study was to investigate the role of aquaporin3 (AQP3) in the colon in the laxative effect of bisacodyl. After oral administration of bisacodyl to rats, AQP3, macrophages, cyclooxygenase 2 (COX2), and prostaglandin E(2) (PGE(2)) were examined in the colon. The mechanism by which bisacodyl decreases the expression of AQP3 was examined using HT-29 and Raw264.7 cells. When diarrhea occurred, a significant increase in the expression of PGE(2) and a decrease in AQP3 expression were observed. Immunostaining showed COX2 expression only in macrophages. The PGE(2) concentration increased significantly 30 min after the addition of bisacodyl to Raw264.7 cells. Thirty minutes after PGE(2) addition to HT-29 cells, the AQP3 expression level decreased to 40% of the control. When pretreated with indomethacin, bisacodyl did not induce an increase in the colon PGE(2) level, a decrease in the AQP3 expression level, or diarrhea. The results suggest that bisacodyl may decrease the expression of AQP3 in the colon, which inhibits water transfer from the luminal to the vascular side and leads to a laxative effect. This study also showed that direct activation of colon macrophages by bisacodyl increases the secretion of PGE(2), which acts as a paracrine factor and decreases AQP3 expression in colon mucosal epithelial cells.     

Effect of pamamycin-607 on secondary metabolite production by Streptomyces spp

The effect of the aerial mycelium-inducing compound, pamamycin-607, on antibiotic production by several Streptomyces spp. was examined. Exposure to 6.6 μM pamamycin-607 stimulated by 2.7 fold the puromycin production by Streptomyces alboniger NBRC 12738, in which pamamycin-607 had first been isolated, and restored aerial mycelium formation. Pamamycin-607 also stimulated the respective production of streptomycin by S. griseus NBRC 12875 and that of cinerubins A and B by S. tauricus JCM 4837 by approximately 1.5, 1.7 and 1.9 fold. The antibiotic produced by Streptomyces sp. 91-a was identified as virginiamycin M(1), and its synthesis was enhanced 2.6 fold by pamamycin-607. These results demonstrate that pamamycin-607 not only restored or stimulated aerial mycelium formation, but also stimulated secondary metabolite production.