The lattice structure of prolamellar body in the plastid of Phaseolus vulgaris cultured in the dark was stereometrically studied on a number of serial sections using electron microscope. The figures varied with the thickness of the sections. Based on these observations, a new scheme was proposed for three dimensional structure of prolamellar body, and a model was constructed according to this scheme. Using this model, various figures obtained by electron microscopy were interpreted in terms of cutting orientation and thickness of sections. From the careful comparison of the micrographic figures and the lattice structure of the model, it is ascertained that the center of interconnecting tubules possesses 4 arms, and that 12 connecting centers are brought into combination to form a three-dimensional lattice, a structural “unit” of the prolameller body.
The effect of EOC, one of radiomimetic chemicals, on the incorporation of 32P1 into RNA and DNA was investigated with the primary roots of Vicia seedlings. The presence of EOC during the period of labelling with 32Pi did inhibit partially or almost completely, depending on the concentrations of EOC, the incorporation of the isotopes into RNA and DNA. The extent of the inhibitory effect by EOC was approximately identical among the fractions of rRNA, mRNA, and the low molecular-weight RNA fraction consisting of tRNA and 5-6S RNA, thus indicating that the action of EOC on chromatin is not of preferential nature to the nucleolar organizer region, though EOC is known to induce the chromosome breaks which are extremely localized to the secondary constriction.
The seasonal changes of phosphorus content and its balance sheet in each organ of the current-year and two-year-old (till August) seedlings of an evergreen conifer, Pinus densiflora and a deciduous conifer, Larix leptolepis were studied under the field conditions of Tokyo. The phosphorus concentration on the dry weight basis was highest in the leaves of both species, and the amplitude of the seasonal variation was larger in the larch than in the red pine. The seasonal changes of dry weight and the total phosphorus contents showed characteristic patterns essentially common to the both species, except for some differences caused mainly by the defoliation in the larch. The total phosphorus content of an entire larch plant was kept almost constant in the latter half of the growing season in spite of the dry matter loss by defoli-ation. Prior to the defoliation, most of phosphorus contained in the leaves was withdrawn in both the species. At the beginning of the growing season the rapid growth of new organs should be supported by the supply of phosphorus reserved in the older organs. About a half the amount of phosphorus accumulated in the first year was translocated and utilized for the growth in the next year.
When the embryo of Sesamum indicum, peeled out of seed coat and deprived of one of the cotyledons, is treated with Amo-1618 at the concentration of 200ppm for 48 hours, the first leaf primordia develop to a double leaf on the decotylated side of the shoot apex. The formation of double leaf is restricted to the case in which one cotyledon is removed and the treatment with Amo-1618 is made within 6 hours after sowing. 2, 4-D induces gamophylls, which partly resemble the double leaf, when it is applied to the embryo deprived of one cotyledon. It also induces gamophylls in the presence of both cotyledons and even when applied to the embryos grown for 24 hours after sowing. Histological observations on the shoot apices of the treated embryos suggest that Amo-1618 induces double leaf by causing structural changes in the apical meristem and leaf primordia, whereas 2, 4-D induces gamophyll by stimulating the interprimordial region in the peripheral zone of the shoot apex. All other chemicals examined, CCC, IAA, NAA, GA, and MH, have no effect of producing double leaf or gamophyll when used in the same manner as Amo-1618 or 2, 4-D was.
Distribution patterns of nucleotides in five different species of edible marine algae were investigated in order to elucidate the possible relation between these nucleotides and flavor of algae. The nucleotides in the extracts from the seaweeds were fractionated by anion-exchange column and paper chromatographies, and identified by spectral and chemical analyses. The contents of nucleotides in these seaweeds were negligibly small except for Porphyraand Hizikia. In the fronds of Porphyra, with both raw and dried, not only a quantity of 5'-IMP but also a few amounts of IDP, CMP, LIMP, and GMP were contained. Only negligible amounts of AMP and ADP, however, were found in the extracts from this alga. In addition, a considerable activity of AMP deaminase which also showed the activity toward ADP was found in Porphyra tenera. It was suggested by these findings that both IMP and IDP might be enzymatically produced in vivo from AMP and ADP, respectively. Thus, it is interesting that IMP which is known to be widely distributed in animals but rarely in plants occurred only in Porphyra among five algae tested. In view of the fact that Porphyra is phylogenetically primitive and most commonly used for food, the occurrence of IMP in this alga is worthy of note. Nucleotide patterns of Porphyra seemed to vary significantly depending on the season, although no details were investigated in this respect.