DISTRIBUTION AND TURNOVER OF PHOSPHATE COMPOUNDS IN GROWING CHLORELLA CELLS

1. Using the Chlorella cells which had been uniformly labeled with³²P, the distribution of phosphorus in various fractions ofcell material was investigated. Uniformly ³²P-labeled Chlorellawas further grown in a P-free medium or in a standard "cold"medium, and the change of distribution of ³²P (as well as theuptake of exogenous P) in various cell fractions was followed.
2. Analysis of the ³²P-labeled algal cells showed that the highestin P-content was the fraction of RNA followed by those of polyphosphates,lipid, nucleotidic labile phosphate compounds, DNA and protein(in decreasing order). ATP and ADP were found to be only minorfractions of the total labile phosphates.
3. On incubating the³P-labeled alga in a P-free medium, the P.contentsin the fractionsof DNA, protein, lipid and ATP increased, thosein polyphosphatesand ADP decreased, and that in RNA remainedalmost unchanged.When the ³²P-labeled alga was further grownin the normal "cold"medium, DNA and protein increased withthe expenditure of endogenous³²P, but with practically no incorporationof external P. Inthe meantime the P in polyphosphates decreasedconsiderably,and the RNA fraction incorporated a large amountof externalP but only a little of endogenous³²P.
4. It was inferred that,under the experimental conditions of thepresent study, thephosphorus used in the syntheses of DNA andprotein was primarilytaken from polyphosphates, while thatused in the synthesesof RNA, phospholipid and polyphosphateswas, for the most part,taken from the extracellular P-source.

¹A part of this paper was read at the Vth International Congressof Biochemistry, Moscow, August 10–16, 1961. (Received June 4, 1961; )     

MODE OF NUCLEAR DIVISION IN SYNCHRONOUS CULTURES OF CHLORELLA: COMPARISON OF VARIOUS METHODS OF SYNCHRONIZATION

1. Chlorella ellipsoidea was grown synchronously using variouspossible techniques and the mode of nuclear division in eachcase was followed by staining the nuclei according to FEULGEN.
2. A satisfactory synchrony in respect to nuclear and cellulardivision was obtained by starting the culture from a homogeneouspopulation of young and small cells and by discontinuing theillumination at the stage which was called the L₃-stage. Thestarting young cells were invariably mononuclear and the L₃-cellswere either dinuclear or tetranuclear. When the L₃ were incubatedin the dark, they ripened further, and after passing througha tetranuclear stage (referred to as the L₄) divided into fourmononuclear daughter cells which have been called the D_n-cells.The most clear-cut and repetitive synchronous culture was obtainedwhen the culture (in the light) was started from the D_n-cellsand the illumination was discontinued at the L₃-stage untilthe fully ripened cells divided into four each of D_n-cells.
3. An apparently "synchronous" culture was also obtained by themethod of programmed light-and-dark regimen, in which a randomculture is subjected to a regular alternation of light and darkperiods of adequate durations. In this case, however, the cellsat different stages of culture showed irregular nuclear patterns,and the average "division number" of mother cells was not constant,being subject to change between 4.0 and 4.9.

(Received May 25, 1961; )     

Up‐regulation of Tyrosinase Gene by Nitric Oxide in Human Melanocytes

Ultraviolet light (UV) radiation causes skin‐tanning, which is thought to be mediated by stimulating the release of melanogenic factors from keratinocytes as well as other cells. Nitric oxide (NO) has been reported to be generated after UV radiation and to stimulate melanocytes as one of the melanogens. In a previous experiment by another group on melanogenesis induced by NO, increases in both tyrosinase activity and tyrosinase protein levels were observed after daily stimulation of NO for 4 days. In the present study, we investigated tyrosinase gene expression within the first 24 hr of NO‐induced melanogenesis. Tyrosinase mRNA expression was found to be induced 2 hr after a single treatment with S‐nitroso‐N‐acetyl‐ l ‐arginine. An increase of tyrosinase activity was also detected time‐dependently within the 24‐hr period, accompanied by an increase of tyrosinase protein levels. The induction of mRNA expression was suppressed by a cyclic guanosine 3′,5′‐monophosphate (cGMP)‐dependent protein kinase (cGMP/PKG) inhibitor. These results suggest that the enhancement of tyrosinase gene expression via the cGMP pathway may be a primary mechanism for NO‐induced melanogenesis.     

Embryology of Hortonioideae and Monimioideae (Monimiaceae,Laurales): characteristics of the ‘lower’ monimioids

We investigated the embryology of the ‘lower’ monimioids, i.e. Monimioideae (Monimia, Palmeria and Peumus) and Hortonioideae (Hortonia), which are poorly described embryologically. Our results show that, contrary to what has been reported in the literature, ‘lower’ monimioids show very little variation in their embryological characters. Comparisons with Mollinedioideae (a large derived subfamily in Monimiaceae) and other families in Laurales show that the ‘lower’ monimioids are relatively consistent in sharing predominantly isobilateral tetrads of microspores and megaspores, a non‐specialized chalaza, and a mesotestal–endotestal seed coat (with tracheoidal cells of the meso‐ and endotesta). It is likely that, while the shared successive cytokinesis during meiosis of microspore mother cells supports the Monimiaceae–Hernandiaceae–Lauraceae clade obtained by molecular evidence, no synapomorphies exist to support a sister‐group relationship of Monimiaceae with Hernandiaceae or Lauraceae. Instead, the lack of hypostase in ovules and/or young seeds, the lack of endosperm in mature seeds and the amoeboid tapetum in the anther are likely synapomorphies of Hernandiaceae and Lauraceae. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 228–241.     

New gammaroid family, genera and species from subterranean waters of Japan, and their phylogenetic relationships (Crustacea: Amphipoda)

Luciobliviidae, a new family in the superfamily Gammaroidea (Amphipoda: Crustacea), is described on the basis of species in the genus Lucioblivio gen. nov. from subterranean waters of Japan. Mesogammaridae Bousfield, 1977 is rediagnosed; Octopupilla gen. nov. from subterranean waters of Japan is described and Eoniphargus (Uéno, 1955) from subterranean waters of Japan and Korea is included. The members of Lucioblivio , Octopupilla and Eoniphargus share several characters, including reduced eyes, a setose body, reduced coxae, feeble appendages and pedunculate coxal gills. To elucidate the phylogeny of the three genera among others, a sequence analysis of the 28S rRNA gene was conducted for 14 species in six families, including the three genera, from the superfamilies, Gammaroidea, Crangonyctoidea and Hadzioidea. The tree from a neighbour-joining analysis and the strict consensus tree from a maximum-parsimony analysis indicate monophyly of Mesogammaridae. Luciobliviidae is embedded within a clade of taxa belonging to the superfamily Gammaroidea. These results and the occurrence of gammarid-type calceoli in species of the new family indicate that Luciobliviidae should be placed within the superfamily Gammaroidea. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 643–670.     

Embryology of Eusideroxylon (Cryptocaryeae, Lauraceae) and character evolution in the family

Lauraceae are relatively well-known embryologically and embryological data are available for 23 of about 50 genera. In this paper we present the embryology of Eusideroxylon , an unstudied and key genus within Cryptocaryeae, which are positioned basally in the evolution of Lauraceae, and discuss the evolution of embryological characters in the family. Based on comparisons of over 50 characters, it was found that Eusideroxylon is consistent with Aspidostemon , the core Cryptocaryeae ( Beilschmiedia , Cryptocarya , Endiandra and Potameia ), Caryodaphnopsis and Cassytha in having a glandular anther tapetum. The core Cryptocaryeae further agrees with both Caryodaphnopsis and Cassytha in having an embryo sac protruding from the nucellus. In light of the phylogenetic trees available, both the glandular tapetum and the embryo sac protruding from the nucellus have evolved as homoplasies in Lauraceae, once each in a clade of Cryptocaryeae, and the Caryodaphnopsis and Cassytha clade, respectively. Such character-state distributions suggest that it is better to place both Caryodapnopsis and Cassytha in the same clade as the core Cryptocaryeae. Embryologically, Eusideroxylon appears to have an intermediate state between Hypodaphnis , a genus positioned basal-most in the family, and the core Cryptocaryeae. Supplementary data on the anther and seed of Hypodaphnis are also provided.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 187–201.     

Effects of dietary inositol with sucrose stimulation on chewing and swallowing motor patterns in larvae of the silkworm Bombyx mori

The effects of dietary inositol with sucrose stimulation on chewing and swallowing motor patterns in the larvae of Bombyx mori L. are investigated. Feeding activities of the larvae are significantly enhanced by a test diet containing an inositol–sucrose mixture compared with a test diet of sucrose only. Motor patterns of the mandibular closer muscle are accelerated with shorter burst durations and shorter inter‐burst intervals with the test diet of inositol–sucrose compared with sucrose. In terms of swallowing behaviours, inositol–sucrose shortens the duration of drinking. Motor patterns of the cibarial compressor muscle are accelerated with shorter burst durations and shorter inter‐burst intervals with the inositol–sucrose mixture. Peripheral interactions between inositol‐ and sucrose‐sensitive cells in the maxilla are not detected. Thus, such interactions cannot explain the positive effects of inositol on chewing and swallowing. Responses of inositol‐sensitive cells in the epipharyngeal sensillum are not affected by sucrose. These results suggest that dietary inositol can modify chewing and swallowing motor patterns when coupled with sucrose stimuli. These modifications may occur in the central neural networks involved in chewing and swallowing motor patterns but not in peripheral sensory interactions.