A variety of studies have examined the sexual life cycle of species belonging to the genus Dinophysis Ehrenberg. Here, we used TEM to investigate the mechanism of cellular fusion during the sexual life cycle in Dinophysis fortii Pavillard. We observed that fusion always occurred between a normal-sized cell and a small cell following attachment of their ventral margins. After cell attachment, the small cell moved toward the epitheca of the normal-sized cell, and the cingular and sulcal lists of the small cell shrunk or were almost lost. The epitheca of the normal-sized cell then opened between the cingulum plates and the upper cingular list, after which the small cell was gradually engulfed. This is the first ultrastructural observation in a dinoflagellate of a larger cell opening its epitheca to engulf the smaller gamete. In another case, the normal-sized cell did not open the epitheca, the cell wall of the attached small cell underwent extensive extracellular digestion, and the cytoplasm appeared to flow into the normal-sized cell via the periflagellar area. Inflow of the nucleus was not observed in this case, suggesting that it represented a failure of sexual fusion. In both cases, membranous separations between the cytoplasm of the two cells were not observed. At the beginning of the fusion process, the nucleus of the small cell was substantially deformed. The planozygote, formed upon completion of sexual fusion, sometimes had two longitudinal flagella, but was identical to a normal vegetative cell in its cellular shape, as already mentioned by previous authors.

Background and Purpose Niemann‐Pick disease type C (NPC) is a lysosomal storage disorder with disrupted intracellular cholesterol trafficking. A cyclic heptasaccharide, 2‐hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD), is a cholesterol solubilizer that is being developed to treat NPC, but its ototoxicity and pulmonary toxicity remain important issues. We have characterized 2‐hydroxypropyl‐γ‐cyclodextrin (HP‐γ‐CD), a cyclic octasaccharide with a larger cavity than HP‐β‐CD, as a candidate drug to treat NPC. However, the molecular target of HP‐γ‐CD with respect to NPC and its potential for clinical application are still unclear. Experimental Approach We investigated the mode of interaction between HP‐γ‐CD and cholesterol by phase‐solubility analysis, proton NMR spectroscopy and molecular dynamics simulations. We then evaluated the therapeutic effects of HP‐γ‐CD compared with HP‐β‐CD using cellular and murine NPC models. Mouse auditory and pulmonary function tests were also conducted. Key Results HP‐γ‐CD solely formed a 1:1 inclusion complex with cholesterol with an affinity similar to that of HP‐β‐CD. In vitro, HP‐γ‐CD and HP‐β‐CD amelioration of NPC‐related manifestations was almost equivalent at lower concentrations. However, at higher concentrations, the cholesterol inclusion mode of HP‐β‐CD shifted to the highly soluble 2:1 complex whereas that of HP‐γ‐CD maintained solely the 1:1 complex. The constant lower cholesterol solubilizing ability of HP‐γ‐CD conferred it with significantly reduced toxicity compared with HP‐β‐CD, but equal efficacy in treating a mouse model of NPC. Conclusions and Implications HP‐γ‐CD can serve as a fine‐tuned cholesterol solubilizer for the treatment of NPC with a wider safety margin than HP‐β‐CD in terms of ototoxicity and pulmonary toxicity.

We examined the possibility that dinoflagellates belonging to genus Dinophysis acquire plastids from certain species of cryptophytes. We measured the abundance of cryptophytes over a 3 yr period in Okkirai Bay, northern Japan by fluorescent in situ hybridization (FISH), using an oligonucleotide probe that specifically binds to the Dinophysis plastid small subunit ribosomal RNA. A high density of FISH-probed cryptophytes always occurred prior to peak occurrences of D. fortii, although the density of FISH-probed cryptophytes did not correlate well with the density of D. fortii. Although further investigation is needed, monitoring of these cryptophyte species may be useful for predicting Dinophysis growth and subsequent outbreaks of diarrhetic shellfish poisoning.

Structural evolution in the isothermal crystallization process of the molten nylon 10/10 traced by timeresolved infrared spectral measurements and synchrotron SAXS/WAXD measurements Abstract. The structural evolution in the isothermal crystallization process of nylon 10/10 from the melt has been clarified concretely on the basis of the time-resolved infrared spectral measurement as well as the synchrotron wide-angle and small-angle X-ray scattering measurements. Immediately after the temperature jump from the melt to the crystallization point, the isolated domains consisting of the hydrogen-bonded random coils were formed in the melt, as revealed by Guinier plot of SAXS data and the infrared spectral data. With the passage of time these domains approached each other with stronger correlation as analyzed by Debye-Bueche equation. These domains transformed finally to the stacked crystalline lamellae, in which the conformationally-regularized methylene segments of the CO sides were connected each other by stronger intermolecular hydrogen bonds to form the crystal lattice.