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.     

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 .     

Saccharification of Complex Cellulosic Substrates by the Cellulase System from Clostridium thermocellum

True cellulase activity has been demonstrated in cell-free preparations from the thermophilic anaerobe Clostridium thermocellum. Such activity depends upon the presence of Ca²⁺ and a thiol-reducing agent of which dithiothreitol is the most promising. Under these conditions, native (cotton) and derived forms of cellulose (Avicel and filter paper) were all extensively solubilized at rates comparable with cellulase from Trichoderma reesei. Maximum activity of the Clostridium cellulase was displayed at 70°C and at pH 5.7 and 6.1 on Avicel and carboxymethylcellulose, respectively. In the absence of substrate at temperatures up to 70°C, carboxymethylcellulase was much more unstable than the Avicel-hydrolyzing activity.     

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.     

Involvement of an autocrine stromal cell derived factor-1/CXCR4 system on the distant metastasis of human oral squamous cell carcinoma

We have previously shown that a stromal cell-derived factor-1 (SDF-1; CXCL12)/CXCR4 system is involved in the establishment of lymph node metastasis, but not in that of distant metastasis, in oral squamous cell carcinoma (SCC). In this study, we investigated the role of the autocrine SDF-1/CXCR4 system, with a focus on distant metastasis in oral SCC cells. The immunohistochemical staining of SDF-1 and CXCR4 using primary oral SCCs and metastatic lymph nodes showed a significantly higher number of SDF-1-positive cases among the metastatic lymph nodes than among the primary oral SCCs, which was associated with a poor survival rate among those of the former group. The forced expression of SDF-1 in B88 cells, which exhibit functional CXCR4 and lymph node metastatic potential (i.e., the autocrine SDF-1/CXCR4 system), conferred enhanced cell motility and anchorage-independent growth potential onto the cells. Orthotopic inoculation of the transfectant into nude mice was associated with an increase in the number of metastatic lymph nodes and more aggressive metastatic foci in the lymph nodes. Furthermore, the SDF-1 transfectant (i.e., the autocrine SDF-1/CXCR4 system) exhibited dramatic metastasis to the lung after i.v. inoculation, whereas the mock transfectant (i.e., the paracrine SDF-1/CXCR4 system) did not. Under the present conditions, AMD3100, a CXCR4 antagonist, significantly inhibited the lung metastasis of the SDF-1 transfectant, ameliorated body weight loss, and improved the survival rate of tumor-bearing nude mice. These results suggested that, in cases of oral SCC, the paracrine SDF-1/CXCR4 system potentiates lymph node metastasis, but distant metastasis might require the autocrine SDF-1/CXCR4 system.     

Ability of CD8(+) T cell anti-feline immunodeficiency virus activity correlated with peripheral CD4(+) T cell counts and plasma viremia

In the host defense mechanism against feline immunodeficiency virus (FIV) infection, CD8(+) T cells specifically attack virus-infected cells and suppress the replication of the virus in a non-cytolytic manner by secreting soluble factors. In this study, we measured CD8(+) T cell anti-FIV activity in 30 FIV-infected cats. We investigated its relationship with the number of peripheral blood lymphocytes, particularly the CD4(+) T cell and CD8(+) T cell counts, and the relationship between anti-FIV activity and the number of T cells of CD8alpha(+)beta(lo) and CD8alpha(+)beta(-) phenotypes. A clearly significant correlation was observed between anti-FIV activity and the number of CD4(+) T cells. A weaker anti-FIV activity was associated with a greater decrease in the number of CD4(+) T cells. However, there was no significant correlation between anti-FIV activity and the number of B or CD8(+) T cells. Compared with SPF cats, FIV-infected cats had significantly higher CD8alpha(+)beta(lo) T cell and CD8alpha(+)beta(-) T cell counts, but, no significant correlation was observed between these cell counts and anti-FIV activity. This anti-FIV activity significantly correlated with plasma viremia, which was detected in cats with a weak anti-FIV activity. These results suggest that the anti-FIV activity of CD8(+) T cells plays an important role in plasma viremia and the maintenance of CD4(+) T cells in the body. It is unlikely that CD8alpha(+)beta(lo) or CD8alpha(+)beta(-) T cells appearing after FIV infection represent a phenotype of CD8(+) cells with anti-FIV activity.     

Fluorescent analysis of excess electron transfer through DNA

The DNA base stack provides unique features for the efficient long-range charge transfer. For the purpose of investigating excess electron transfer process through DNA, we developed a new method for fluorescence analysis of excess electron transfer based on reductive cleavage of a disulfide bond and a thiol-specific fluorescent probe. Excess electron transfer was detected by monitoring the fluorescence of emissive pyrene monomer generated by the reaction of pyrene maleimides with the cleaved disulfide bond (thiols). Mechanism of reductive cleavage of disulfides through excess electron transfer and subsequent reaction with the fluorescent probes were discussed. This facile and sensitive detection by fluorescence method can be applied for mechanistic study of excess electron transfer.