Caged bulky organic dyes in a polyaromatic framework and their spectroscopic peculiarities.

Host-guest structures and properties have been widely studied using relatively small dyes (<1 nm) without bulky groups, due to their smooth incorporation, efficient host-guest interactions, and high analytical accessibility. In this report, on the other hand, three types of sterically demanding organic dyes trapped by a polyaromatic cage were investigated by spectroscopic analyses on the basis of supramolecular interactions. Coumarins with two bulky substituents are bound by the cage in aqueous solution. The resultant caged dyes show unusual emission enhancement, depending on the difference of a single heteroatom in their substituents. The color of perylene bisimides with two bulky substituents is remarkably changed from yellow to red upon caging. This peculiarity stems from the twist of the substituents in the cage, revealed by the combination of absorption and theoretical studies. Furthermore, tetrasubstituted, bulky porphyrins are caught by the cage in aqueous solution. The caged bulky dyes also display altered color and absorption properties, which remain intact even under acidic conditions. In contrast to typical covalent functionalization and previous host-guest studies toward small and non-bulky dyes, the unusual, non-covalent spectroscopic modulation of the large and bulky dyes can be accomplished for the first time by the present cage, featuring a prolate polyaromatic framework with four openings.

The fertilization ability and developmental competence of bovine oocytes grown in vitro.

In vitro growth culture systems for oocytes are being developed in several mammalian species. In these growth culture systems, in vitro grown oocytes usually have lower blastocyst formation than in vivo grown oocytes after in vitro fertilization. Furthermore, there have been a few reports that investigated the fertilization ability of in vitro grown oocytes in large animals. The purpose of this study was to investigate the fertilization process and developmental competence of bovine oocytes grown in vitro. Oocyte-granulosa cell complexes collected from bovine early antral follicles (0.4-0.7 mm in diameter) were cultured for growth with 17ß-estradiol and androstenedione for 14 days and matured in vitro. These oocytes were then inseminated for 6 or 12 h, and further cultured for development up to 8 days in vitro. After growth culture, oocytes grew from 95 µm to around 120 µm and acquired maturation competence (79%). Although fertilization rates of in vitro grown oocytes were low after 6 h of insemination, 34% of in vitro grown oocytes fertilized normally after 12 h of insemination, having two polar bodies and two pronuclei with a sperm tail, and 22% of these oocytes developed into blastocysts after 8 days of culture. The fertilization and blastocyst formation rates were similar to those of in vivo grown oocytes. In addition, blastocyst cell numbers were also similar between in vitro and in vivo grown oocytes. In conclusion, in vitro grown bovine oocytes are similar to in vivo grown oocytes in fertilization ability and can develop into blastocysts.

Divergence and heterogeneity of the histone gene repeating units in the Drosophila melanogaster species subgroup.

The repeating units of the histone gene cluster containing the H1, H2A, H2B and H4 genes were amplified by PCR from the Drosophila melanogaster species subgroup, i.e., D. yakuba, D. erecta, D. sechellia, D. mauritiana, D. teissieri and D. orena. The PCR products were cloned and their nucleotide sequences of about 4.6-4.8kbp were determined to elucidate the mechanism of molecular evolution of the histone gene family. The heterogeneity among the histone gene repeating units was 0.6% and 0.7% for D. yakuba and D. sechellia, respectively, indicating the same level of heterogeneity as in the H3 gene region of D. melanogaster. Divergence of the genes among species even in the most closely related ones was much greater than the heterogeneity among family members, indicating a concerted mode of evolution for the histone gene repeating units. Among the species in the D. melanogaster species subgroup, the histone gene regions as well as 3rd codon position of the coding region showed nearly the same GC contents. These results suggested that the previous conclusion on analysis of the H3 gene regions, the gene family evolution in a concerted fashion, holds true for the whole histone gene repeating unit.