Cytokinin Activity of Benzoylaminodeazapurines, Pentanoylaminodeazapurines and their Corresponding Purine Analogs in Five Bioassays

Cytokinin activities of 6-benzoylamino-1, 6-benzoylamino-3-, 6-pentanoylamino-1- and 6-pentanoylamino-3-deazapurines and their corresponding purine analogs, 6-benzoylaminopurine and 6-pentanoylaminopurine, were examined using five bioassay systems, tobacco callus growth, bud formation on tobacco callus, lettuce seed germination, fresh weight increase of radish cotyledons and retardation of chlorophyll degradation in radish cotyledons. 6-Benzoylamino- and 6-pentanoylamino-1-deazapurines showed stronger cytokinin activity than their corresponding purine analogs in all bioassays used. In tobacco callus growth, 6-benzoylamino-1-deazapurine was nearly as active as zeatin, one of the most active adenylate cytokinins. On the other hand, 6-benzoylamino- and 6-pentanoylamino-3-deazapurines were as active as or less active than corresponding purine analogs.     

Crystal Structures of Human Dipeptidyl Peptidase Ⅳ in its Apo and Diprotin B-complexed Forms

Dipeptidyl peptidase Ⅳ (DPPIV), which belongs to the prolyl oligopeptidase family of serine proteases, is known to have a variety of regulatory biological functions and has been shown to be implicated in type 2 diabetes. It is therefore important to develop selective human DPPIV (hDPPIV) inhibitors. In this study, we determined the crystal structure of apo hDPPIV at 1.9 A resolution. Our high-resolution crystal structure of apo hDPPIV revealed the presence of sodium ion and glycerol molecules at the active site. In order to elucidate the hDPPIV binding mode and substrate specificity, we determined the crystal structure of hDPPIV-diprotin B (Val-Pro-Leu) complex at 2.1 A resolution, and clarified the difference in binding mode between diprotin B and diprotin A (Ile-Pro-Ile) into the active site of hDPPIV. Comparison between our crystal structures and the reported apo hDPPIV structures revealed that positively charged functional groups and conserved water molecules contributed to the interaction of ligands with hDPPIV. These results are useful for the design of potent hDPPIV inhibitors.     

Distribution of the Argentine ant, Linepithema humile, along the Seto Inland Sea, western Japan: Result of surveys in 2003–2005

The distribution of the Argentine ant, Linepithema humile, was investigated in 65 cities or towns along the Seto Inland Sea, western Japan in 2003–2005. Our results include all available information of their distribution in Japan until 2005. Argentine ants have invaded Aichi Prefecture (Tahara‐shi), Hyogo Prefecture (Kobe‐shi), Hiroshima Prefecture (Hiroshima‐shi, Fuchu‐cho, Hatsukaichi‐shi, Ono‐cho and Otake‐shi), and Yamaguchi Prefecture (Iwakuni‐shi and Yanai‐shi). The most widespread distribution was found around Hatsukaichi‐shi including the westernmost part of Hiroshima‐shi and the easternmost of Ono‐cho.     

INCORPORATION OF AMINO ACIDS INTO SEA URCHIN EGGS STIMULATED INSUFFICIENTLY WITH AN ACTIVATING REAGENT

Investigations were performed on the incorporation of valine-¹⁴C and leucine-³H into sea urchin eggs which were stimulated insufficiently with an activating reagent. Materials used were Pseudocentrotus, Hemicentrotus and Anthocidaris. An insufficient stimulation enhanced the incorporation of amino acids into the eggs, although it provoked no visible cortical changes. The amount of incorporation in this case was 1.6 to 2.7 times as much as that into untreated eggs. In fully activated eggs, the amount of incorporation was more than 4 times that in untreated eggs. The fact that the incorporation of amino acids is increased without accompanying breakdown of the cortical granules indicates that the increase may be linked to an invisible change, probably the fertilizationwave, which is caused by an insufficient stimulation.     

A morphological study of the development of the second inflorescences in strawberry (Fragaria×ananassa Duch.)

To clarify the timing of the differentiation of the first and second inflorescences in strawberry (Fragaria × ananassa Duch.), morphological changes on shoot apices during short day and low night temperature treatments were observed by scanning electron microscopy (SEM) and optical microscopy. Axillary buds just below the first inflorescence (axillary bud 1) became visible when sepal primordia of the primary flower were differentiated. By this time, other axillary buds had already developed. Axillary bud 1 developed four leaf primordia, and then a differentiated inflorescence at its summit. The phase transition of shoot apices from the vegetative to the reproductive phase may therefore trigger the differentiation of axillary bud 1 which is destined to develop into extension crowns.     

OCCURRENCE OF MUCOPOLYSACCHARIDES IN THE EARLY DEVELOPMENT OF THE SEA URCHIN EMBRYO AND ITS ROLE IN GASTRULATION

The occurrence of acid mucopolysaccharides in the early development of the sea urchin embryo was studied by histochemical stainings as well as by autoradiographic methods. By histochemical methods acid niucopolysacchdride was demonstrated at the vegetal region in the early stage of gastrulation as a globular structure. Experiments with ³⁵S-labeled sulfate which was incorporated into acid mucopolysaccharides confirmed the result obtained by histochemical observation. It was revealed that sulfate polysaccharide in the vegetal region moved toward the blastocoel in parallel with the shedding of the primary mesenchyme cells. When the incorporation of sulfate into the acid mucopolysaccharides was inhibited by selenate, the primitive gut development was remarkably repressed. The substance seems to be indispensable for smooth cell movements essential for the gastrulation of sea urchin embryo.     

Development of a novel pink-eyed dilution mouse model showing progressive darkening of the eyes and coat hair with aging

Oca2^p-cas (oculocutaneous albinism II; pink-eyed dilution castaneus) is a coat color mutant gene on mouse chromosome 7 that arose spontaneously in wild Mus musculus castaneus mice. Mice homozygous for Oca2^p-cas usually exhibit pink eyes and gray coat hair on the non-agouti genetic background, and this ordinary phenotype remains unchanged throughout life. During breeding of a mixed strain carrying this gene on the C57BL/6J background, we discovered a novel spontaneous mutation that causes darkening of the eyes and coat hair with aging. In this study, we developed a novel mouse model showing this unique phenotype. Gross observations revealed that the pink eyes and gray coat hair of the novel mutant young mice became progressively darker in color by approximately 3 months after birth. Light and transmission-electron microscopic observations revealed a marked increase in melanin pigmentation of coat hair shafts and choroid of the eye in the novel mice compared to that in the ordinary mice. Sequence analysis of Oca2^p-cas revealed a 4.1-kb deletion involving exons 15 and 16 of its wild-type gene. However, there was no sequence difference between the two types of mutant mice. Mating experiments suggested that the novel mutant phenotype was not inherited in a simple fashion, due to incomplete penetrance. The novel spontaneous mutant mouse is the first example of progressive hair darkening animals and is an essential animal model for understanding of the regulation mechanisms of melanin biosynthesis with aging.     

SPECIES-SPECIFIC ADHESION OF SPERMATOZOA TO THE SURFACE OF FIXED EGGS IN SEA URCHINS

When the spermatozoa of sea urchins are added to eggs which have been fixed with glutaraldehyde and washed thoroughly, the spermatozoa swarm around the eggs and adhere to the egg surface. The mode of sperm adhesion to the fixed egg is assumed, on the evidence of electron-microscopical studies, to be the same as that of adhesion to the intact egg at the initial stage of normal fertilization. The spermatozoa and fixed eggs of five species of sea urchins were combined and heterologous crosses were studied. Species-specific adhesion of sperm to fixed eggs was clearly demonstrated. There is a direct relationship between the cross-fertilization of living gametes and the binding capacity of spermatozoa and fixed eggs in so far as the employed five species are concerned.     

Roles of Head-Activation and Head-Inhibition Potentials in Pattern Formation of Hydra: Analysis of a Multi-Headed Mutant Strain

SYNOPSIS. Lateral grafting of tissue was used to compare therelative head-activation and head-inhibition potentials of differentHydra strains. A small piece of tissue taken from one polyp,when grafted to another polyp, induces formation of a head structurewhen the relative head-activation potential of the donor tissueis sufficiently (i.e., more than some threshold value) higherthan the relative head-inhibition potential of the recipienttissue. It was found that a multi-headed mutant strain (mh-1),which produces many extra heads along its body column, has significantlyhigher head-activation and significantly lower head-inhibitionpotentials than the standard wild-type strain. This suggeststhat these potentials play important roles in hydra morphogenesis,and that an imbalance between the two potentials is responsiblefor the developmental abnormality of mh-1. The significanceof this finding is discussed in light of the "positional information"model proposed by Wolpert and his associates and the "lateralinhibition" model proposed by Gierer and Meinhardt.