A morphological study and hybridization analysis of Caloglossa leprieurii (Ceramiales, Rhodophyta) from Japan, Singapore and Australia

Morphological and hybridization experiments were performed on Caloglossa leprieurii (Montagne) J. Agardh collected from Japan, Singapore and Australia in order to evaluate taxonomic characters of this species. Within C. leprieurii at least four mating groups were recognized from the Indo-Pacific region. These mating groups could be characterized by the blade width at the inter-node and the cell-row numbers on the opposite side derived from the first axial cell at the main axis, though these properties showed a certain variability even in the same plant under both field and culture conditions. The phylogenetic relationship and geographic distribution of the four mating groups are discussed.     

Morphology and molecular phylogeny of the marine diatom genus Nagumoea (Bacillariophyceae) from Japan

The canal-bearing diatom genus Nagumoea, described based on only morphological evidence, was tentatively assigned to the order Bacillariales, although its phylogenetic position remained unclear. Because three isolates of Nagumoea (SK002, SK024 and SK053) were successfully established from Japanese coasts, we performed their morphological observations and molecular phylogenetic analyses to discuss the phylogeny and taxonomic position of this genus. Strains SK002 and SK024 were identified as Nagumoea africana, whereas SK053 conformed with Nagumoea serrata. There was high interspecific divergence between N. africana and N. serrata in the rbcL sequences (8.03–8.17%), indicating their distinctness. Furthermore, intraspecific variations were detected within N. africana (2.35%) in the rbcL, implying its cryptic diversity. The maximum likelihood and Bayesian phylogenetic trees inferred from the plastid rbcL, psbC and nuclear 18S rDNA genes recovered Nagumoea as monophyletic with strong statistical support and embedded within an unresolved, poorly supported lineage containing Achnanthes, Craspedostauros, Staurotropis and Undatella in the canal-bearing order Bacillariales (= the family Bacillariaceae). Although the constrained tree based on the monophyly of Nagumoea and the other canal-bearing clade (Surirellales and Rhopalodiales) was statistically rejected by the topology tests, the phylogenetic position of Nagumoea with other Bacillarialean members remains equivocal. The possession of two plastids positioned fore and aft, observed in the present study, and lack of keel, typical of the Bacillariales, indicate the possibility of Nagumoea being part of the ingroup of the Bacillariales or its closely related outgroup.     

Specific bindings of [3H](+)PN200-110 and [125I]ω-conotoxin to crude membranes from differentiated NG108-15 cells

The characteristics of the specific bindings of [³H](+)PN200-110 (PN: L-type Ca channel antagonist) and [¹²⁵I]-conotoxin G VI A (-CgTX: neuronal L-or N-type Ca channel antagonist) to crude membranes from undifferentiated neuroblastoma x glioma hybrid NG108-15 (NG108-15) cells and differentiated cells induced with dibutyryl cAMP (Bt₂cAMP) were examined, because we have already observed that the magnitude and rate of KCL-stimulated⁴⁵Ca uptake by NG108-15 cells increased progressively during differentiation of the cells induced with Bt₂cAMP (unpublished results). The specific binding of [³H](+)PN to these crude membranes was saturable at various concentrations of 2.5–5.0 nM [³H](+)PN. Scatchard analysis showed that the specific binding of [³H](+)PN at equilibrium was significantly increased after differentiation of the NG108-15 cells with Bt₂cAMP, but that the apparent Kd value for the specific binding of [³H](+)PN was not influenced by treatment with Bt₂cAMP. The specific binding of [³H](+)PN to crude membranes from Bt₂cAMP-treated NG108-15 cells was inhibited by a calcium agonist and antagonists, the order of their inhibitory potencies being (+)PN>nitrendipine>(–)PNBay K 8644diltiazem = verapamil. Thus, PNs showed significant stereoselective inhibition of the specific binding of [³H(+)PN. On the other hand, [¹²⁵I]-CgTX at concentrations of 0.075–0.6 nM showed scarcely any specific binding to these crude membranes, although at 0.6 nM it showed specific binding to crude membranes from rat brain in the same experimental conditions. These results suggest that the increase in magnitude or rate of KCl-stimulated⁴⁵Ca uptake during differentiation of NG108-15 cells is partially due to quantitative alteration of voltage-sensitive Ca channels in the cells, and that there are scarcely any specific binding sites for [¹²⁵I]-CgTX on Bt₂cAMP-treated or untreated NG108-15 cells.     

Characteristics of specific125I-ω-conotoxin GVIA binding in rat whole brain

Characteristics of specific¹²⁵I-omega-conotoxin (-CgTX) binding were systematically investigated in crude membranes from rat whole brain. Kd and Bmax Values for the binding were 49.7 pM and 181.5 fmol/mg of protein, respectively. The effects of various types of Ca channel antagonists on the binding were investigated. Dynorphin A (1–13), in particular, specifically inhibited¹²⁵I--CgTX binding, but not that of [³H](+)PN200-110. Spider venom fromPlectreurys tristes did not specifically inhibit specific binding of¹²⁵I--CgTX, because the venom also inhibited the binding of [³H](+)PN200-110 to a similar degree. The amount of specific binding of¹²⁵I--CgTX was less in the cerebellum than that in any other area of whole brain. The cross-linker disuccinimidyl suberate did not label with¹²⁵I--CgTX and its binding sites in rat whole brain, although it did in chick whole brain, which was used as a positive control. These findings suggested that dynorphine A (1–13) was a selective blocker of -CgTX-sensitive Ca channels in crude membranes from rat whole brain and that -CgTX-sensitive Ca channels were mainly present a rat brain except cerebellum.     

COMPARATIVE MORPHOLOGY, CROSSABILITY, AND TAXONOMY WITHIN THE CALOGLOSSA CONTINUA (DELESSERIACEAE, RHODOPHYTA) COMPLEX FROM THE WESTERN PACIFIC

Systematic studies were undertaken on the Caloglossa continua ( Okamura) King et Puttock complex from Japan, Singapore, and Australia, based on morphology and reproductive compatibility. Specimens from Japan had two to six cell rows derived from a nodal axial cell, at the margin opposite the branch, whereas those from Australia possessed only a single cell row. Specimens from Singapore formed one to four cell rows per nodal axial cell and always contained at least one single cell row on any one thallus. These differences were maintained in cultured materials over a range of temperatures or salinities. Type material of C. continua had the same morphology as the Japanese specimens in this study. Carpospores discharged from the Japanese isolate germinated at 10°C, whereas those from Singapore and Australia died at this temperature. In hybridization experiments, the Japanese entity was completely nonfertile with both the Singaporean and Australian isolates. Many pseudocystocarps were produced in the crossing between the male from Australia and the female from Singapore, although the reciprocal combination did not produce any such structures. On the basis of the discontinuous morphology coupled with the complete reproductive isolation, the entities from Singapore and Australia are described here as C. monosticha sp. nov. The entities with multiple cell rows likely expanded their geographic range from tropical regions, where the majority of Caloglossa species are now distributed, to high-latitude regions, and such an expansion would be associated with acquiring low-temperature tolerance .     

Incorporation of β‐amino acids into ascidiacyclamides: Effects on conformation,cytotoxicity and interaction with copper (II) ion

Seven ascidiacyclamide [cyclo(–Ile–oxazoline–d ‐Val–thiazole–)₂] (ASC) analogues incorporating the β‐amino acids βIle, βoxazoline, and/or d ‐βVal were synthesized. We then investigated the effects of the position and number of incorporated β‐amino acids on the structure, cytotoxicity, and copper binding by these seven analogues. The structural analyses revealed that both βIle and d ‐βVal favor a gauche‐type θ torsion angles, while βoxazoline favors a trans‐type θ torsion angle. Expansion of the macrocycle by incorporation of βIle or d ‐βVal readily induced molecular folding. On the other hand, the incorporation of two βoxazoline residues strongly extended the peptide conformation, and the incorporation of one was sufficient for the moderate restriction important for conformational equilibrium and cytotoxicity. Despite expansion of the macrocycles, the structure‐cytotoxicity relationships were largely maintained. In studies of complexation of the analogues with Cu (II) ion, the position and number of incorporated β‐amino acids had a large impact on the structure of the metal complex and may contribute to its stabilization.     

Significant increase in plasma 4β-hydroxycholesterol concentration in patients after kidney transplantation

Several previous studies have shown that renal failure decreases not only renal elimination but also metabolic clearance of drugs, particularly those metabolized by CYP3A. However, whether recovery of renal function results in recovery of hepatic CYP3A activity remains unknown. In this study, we evaluated the effect of renal function on CYP3A activity after kidney transplantation in patients with end-stage renal disease (ESRD) by measuring the change in CYP3A activity using plasma concentration of 4β-hydroxycholesterol as a biomarker. The study enrolled 13 patients with ESRD who underwent the first kidney allograft transplantation. Morning blood samples were collected before and 3, 7, 10, 14, 21, 30, 60, 90, 120, 150 and 180 days after kidney transplantation. Plasma concentration of 4β-hydroxycholesterol was measured using GC-MS. Compared with before kidney transplantation, creatinine clearance increased significantly from day 3 after kidney transplantation and stabilized thereafter. Plasma concentration of 4β-hydroxycholesterol was elevated significantly on days 90 and 180 after kidney transplantation. In conclusion, this study suggests the recovery of CYP3A activity with improvement in renal function after kidney transplantation in patients with ESRD.