Recent progress of chicken genome projects has revealed that bird ZW and mammalian XY sex chromosomes were derived from different autosomal pairs of the common ancestor; however, the evolutionary relationship between bird and reptilian sex chromosomes is still unclear. The Chinese soft-shelled turtle (Pelodiscus sinensis) exhibits genetic sex determination, but no distinguishable (heteromorphic) sex chromosomes have been identified. In order to investigate this further, we performed molecular cytogenetic analyses of this species, and thereby identified ZZ/ZW-type micro-sex chromosomes. In addition, we cloned reptile homologues of chicken Z-linked genes from three reptilian species, the Chinese soft-shelled turtle and the Japanese four-striped rat snake (Elaphe quadrivirgata), which have heteromorphic sex chromosomes, and the Siam crocodile (Crocodylus siamensis), which exhibits temperature-dependent sex determination and lacks sex chromosomes. We then mapped them to chromosomes of each species using FISH. The linkage of the genes has been highly conserved in all species: the chicken Z chromosome corresponded to the turtle chromosome 6q, snake chromosome 2p and crocodile chromosome 3. The order of the genes was identical among the three species. The absence of homology between the bird Z chromosome and the snake and turtle Z sex chromosomes suggests that the origin of the sex chromosomes and the causative genes of sex determination are different between birds and reptiles.

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Populations of the gecko lizard Gekko hokouensis (Gekkonidae, Squamata) on Okinawajima Island and a few other islands of the Ryukyu Archipelago, Japan, have the morphologically differentiated sex chromosomes, the acrocentric Z chromosome and the subtelocentric W chromosome, although the continental representative of this species reportedly shows no sex chromosome heteromorphism. To investigate the origin of sex chromosomes and the process of sex chromosomal differentiation in this species, we molecularly cloned the homologues of six chicken Z-linked genes and mapped them to the metaphase chromosomes of the Okinawajima sample. They were all localized to the Z and W chromosomes in the order ACO1/IREBP-RPS6-DMRT1-CHD1-GHR-ATP5A1, indicating that the origin of ZW chromosomes in G. hokouensis is the same as that in the class Aves, but is different from that in the suborder Ophidia. These results suggest that in reptiles the origin of sex chromosomes varies even within such a small clade as the order Squamata, employing a variety of genetic sex determination. ACO1/IREBP, RPS6, and DMRT1 were located on the Z long arm and the W short arm in the same order, suggesting that multiple rearrangements have occurred in this region of the W chromosome, where genetic differentiation between the Z and W chromosomes has been probably caused by the cessation of meiotic recombination.

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Polarity of several ionic liquids was examined by 14N hyperfine coupling constant of nitroxide radical measured by EPR method. Polarity judged from EPR agrees well with those by solvatochromic dyes, suggesting that EPR is another valuable probe for polarity of ionic liquids.

Low-temperature infrared spectra of thermally evaporated ionic liquids, 1-ethyl- and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and bis(trifluoromethanesulfonyl)amide have been measured in a cryogenic Ne matrix. The experimental IR spectrum of bis(trifluoromethanesulfonyl)amide can be reproduced theoretically by not B3LYP/6-31G* but MP2/6-31G* calculation, which suggests that the vibrational analysis for ionic liquids composed of bis(trifluoromethanesulfonyl)imide anion would be more successfully performed using the MP2 calculation. By comparison of the matrix-isolation spectra of the ionic liquids with the MP2 calculation, their geometrical structures in the gas phase are determined to be of C(2-position)-H(+)...N(-) interaction structure, which corresponds to the geometry of the energetically second-lowest ion-pair structure. The present study may provide a valuable clue to understand a vaporization mechanism of ionic liquid.

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The concentration dependence of free radicals (TEMPO) of enhanced absorptive chemically induced dynamic electron polarization (CIDEP) spectra was studied quantitatively to clarify the mechanism of CIDEP generation in excited singlet stateradical systems. It was experimentally demonstrated that the CIDEP intensity on the free radical was in proportion to the concentration of the spin-polarized free radical. The rate constant of the CIDEP generation was determined to be (6.3 f 0.2) X lo9 M-l s-l from the Stern-Volmer plots of CIDEP intensity in the coronene-TEMPO system in benzene. The absorptive CIDEP spectra were attributed to the free radicals which enhanced the SI-Tl intersystem crossing and were interpreted by introducing the stochasticLiouville equation into the radical-triplet pair mechanism with doublet precursor.