Wrong Perceptions Caused by Textbook Illustrations ： Fertilization Phenomenon in High School Biology

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The Method of Teaching "Experiment on Extracion of DNA"

指導法・実践報

Lessons and lesson ideas using chicken eggs as materials

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Teaching Methods for Scientific Experiments Using Rice as a Component: Cooking Rice Using Plastic Bags

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Simple Cultivation Method of Paramecium Using EBIOS

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Benzothiazolylphenol–Substituted Ketoester is a Useful Fluorescent Probe for Detection of the Mitochondrion in Sea Urchin Sperm

One of the ketoesters derived from benzothiazolylphenol-substituted dioxetane,benzothiazolylphenol-substituted ketoester (TPKE), demonstrates fluorescence in a 0.1 MNaOH 1). In this study, the fluorescent staining of a living cell with TPKE was demonstratedby fluorescence microscopy. When sperm from two species of sea urchins—Pseudocentrotusdepressus and Anthocidaris crassispina—were used as biological materials, TPKE showed afluorescent signal in the midpiece that was composed of a single mitochondrion. The ratioof fluorescent signal intensity to background noise (S/N) was high in the sperm stained with1.0–5.0 μg/ml TPKE in normal artificial seawater (pH 8.0). The S/N ratio decreased inacidic seawater (pH 6.0); acidic conditions repress respiratory activity in sea urchin sperm.Moreover, in the presence of the respiratory chain inhibitor antimycin A and the uncouplercarbonyl cyanide p--trifluoromethoxyphenyl-hydrazone, the sperm showed faint or nofluorescence in normal artificial seawater (pH 8.0). Sea urchin sperm stained with TPKEafter fixation showed faint or no fluorescence. These results suggest that TPKE is apotential fluorescent probe of living sea urchin sperm mitochondria with high respiratoryactivities

The potentiation of Nodal signaling in the right lateral plate mesoderm inverts the left-right specification of the internal organs.

In Xenopus, multiple nodal-related genes are expressed during early embryogenesis. Among them, only Xenopus nodal related-1(Xnr-1) is expressed unilaterally in the left lateral plate mesoderm(LPM) at the late neurula-early tailbud stage. Early studies report that ectopic administration of Xnr-1 in the right hemisphere at the cleavage stage alters the left-right specification of the heart and visceral organs, or else makes a secondary axis. However, because Xnr-1 and other Xnrs function already at the blastula-gastrula stage, it is very difficult to evaluate the correct timing of the effects of excessively administered Xnr-1 from such a method. To elucidate the essential role of Xnr-1 within the left LPM, ectopic potentiation of Nodal signaling in the right lateral plate mesoderm was performed. Right-side injection of Nodal protein changed the laterality of Xnr-1 and Xenopuspitx2, but lefty, and fully (more than 90%) reversed the situs of the internal organs. Polyethyleneimine-based gene transfer of Xnr-1 mRNA in the right LPM also changed the laterality of pitx2 and fully (more than 90%) reversed the situs of the internal organs. Taken together, the potentiation of Xnr-1 signaling in the right LPM induces pitx2 in the right side and fully inverts the left-right axis of the heart and visceral organs, suggesting that the right LPM can transduce Nodal signaling, and only the absence of the Xnr-1 ligand silences the Nodal signaling in the right LPM. Normal left-right balance of Xnr-1 signaling is needed for the normal left-right specification of the internal organs

Detection of the Centrosomal DNA from the Sperm of Bryophyte Marchantia polymorpha L. and Physcomitrella patens

The liverwort Marchantia polymorpha is dioecious and haploid during most of its life cycle. It is known that fertilization in bryophytes, as in animals, involves sperm and eggs. Recently, we isolated novel DNA from the sperm centrosome of the starfish Asterina pectinifera. In the present study, we examined whether the sperm of bryophytes contain this unique DNA. The total DNA in the sperm of M. polymorpha was used as a template for polymerase chain reaction (PCR) analysis performed using a centriole-specific DNA primer. Although this primer was designed to specifically amplify the centrosomal DNA of the starfish, it can amplify the centrosomal DNA of many other animals having a similar DNA sequence. The size of the amplified PCR products was approximately 500 bp, which is similar to that of the PCR products amplified from starfish. We determined the nucleotide sequence similarities between the PCR products amplified from the cultured cells of the moss Physcomitrella patens and from the sperm of the liverwort M. polymorpha. Our results show that DNA similar to that of the starfish centrosomal DNA exists in bryophytes and includes animal centrosomal DNA homologues and candidate centrosomal DNA

Screening for an Efficient Procedure to Generate Non-Congenital Albino Zebrafish using Chemical Compounds or Antisense Oligonucleotides

Zebrafish is a good model organism for developmental biology and biomedicalresearch. In its early developmental stages, zebrafish is very transparent, and the speed ofdevelopment is rapid, however, its larva is highly pigmented, and thus it is almostimpossible to observe the internal organs using non-invasive methods. Here we report theeffects of antisense morpholino oligonucleotides (MO) and organic compounds which targetzebrafish melanogenesis. Antisense MO for zebrafish tyrosinase and phenyl-thiourea(PTU) are highly effective to reduce the pigmentation of melanosomes in melanophores.Arbutin and Kojic acid are partially effective, and Fullerene C60 is not effective forinhibiting zebrafish melanogenesis. Except for pigmentation, all these reagents did notdisrupt normal embryogenesis and the left-right specification of the heart. After 8-daytreatment with PTU, we succeeded in visualizing the shape of the brain ventricle byinjecting with Qdot 655 (red nanocrystal). The inhibition of melanogenesis is useful for thestudy of brain development using zebrafish larvae.■原 著■ 2007 年度神奈川大学総合理学研究所共同研究助成論