Phylogeography of the Japanese giant flying squirrel, Petaurista leucogenys (Rodentia: Sciuridae): implication of glacial refugia in an arboreal small mammal in the Japanese Islands

To test the association between temperate forest dynamics and glacial refugia for arboreal small mammals, we studied the phylogeography of the Japanese giant flying squirrel ( Petaurista leucogenys ) using complete mitochondrial cytochrome b gene sequences (1140 bp). This squirrel is endemic to three of Japan's main islands: Honshu, Shikoku, and Kyushu. We examined 58 specimens of P. leucogenys collected from 40 localities in Japan. Additionally, two individuals with unknown sampling localities were included in phylogenetic analyses. There were 54 haplotypes of P. leucogenys. We found five major phylogroups (Northern, Central, South-eastern, South-western, and Southern). These phylogroups may have originated from glacial refugia during the Late Pleistocene. After the last glaciation, the Northern phylogroup, widely distributed in eastern Japan, could have extensively expanded northward from its refugia. By contrast, in western Japan, population expansion was restricted to western Japan. All members of four phylogroups existed in western Japan during glaciations. The complicated phylogeographical pattern of P. leucogenys populations originating from western Japan may have resulted from the long history.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 47–60.     

Mode of Action of some Stimulants of the Hatching Enzyme Secretion in Fish Embryos*

Mode of action of two stimulants of the hatching enzyme secretion, electric current (AC) and potassium cyanide, was analyzed by applying them to Medaka embryos in the presence or absence of suppressants of nervous system-mediated secretion, tetrodotoxin or MS–222. Electric current (AC) stimulated the secretion of the hatching gland of the embryos that had been treated with these suppressants, while potassium cyanide did not. These results strongly suggest that electric current acts as a stimulant of hatching enzyme secretion directly on the gland cell itself, while potassium cyanide stimulates the secretion indirectly, probably through nervous system of the embryo. In the present experiments, it was also shown that Ca²⁺ and ionophore, X-537A, when applied directly to the hatching gland extracellularly, induced a marked secretion-associated morphological change of the gland cells instantaneously. However, it was found that chum salmon prolactin did not induce the secretion-associated morphological changes in the hatching gland cells when it was applied directly to the gland cells in situ or indirectly through embryonic circulation.     

Photoactivation of Oxygen-evolving System in Dark-grown Spruce Seedlings

Plastids prepared from dark-grown spruce seedlings showed a negligible activity of photosystem II, and no fluorescence variation was observed during actinic illumination. The photosystem II reaction centre, however, was present in primary thylakoids. Exposure of such seedlings to continuous light induced the development of photosystem II activity via three stages (rapid, lagged and gradual), and the variable fluorescence appeared. The rapid development of photosystem II may be attributed to the activation of the oxygen-evolving system, possibly the manganese-catalyzing site, and the lagged and gradual developments may be closely related to the formation of thylakoid membranes and their assembly to grana.     

Photoactivation of the latent O2-evolving center in chloroplasts isolated from dark-grown spruce seedlings

The latent O₂-evolving center in chloroplasts isolated from spruce [Picea abies (L.) Karst.] seedlings grown in the dark was readily activated by pre-illuminating the chloroplast suspension with weak white light. The photoactivation depended on pH with the optimum at pH 7–8, and was strongly stimulated by ascorbic acid. The optimal stimulation was also obtained at pH 7–8. The temperature dependence of the photoactivation suggested the involvement of some dark reaction in the activation process.     

Phylogeography of two sympatric giant flying squirrel subspecies,Petaurista alborufus lena and P. philippensis grandis (Rodentia: Sciuridae), in Taiwan

To test the association between Pleistocene forest dynamics relative to elevation and the population dynamics of arboreal small mammals, we examined the phylogeographical predictions for the genetic structure of the red and white giant flying squirrel (Petaurista alborufus lena) and the Indian giant flying squirrel (P. philippensis grandis) using complete mitochondrial control region sequences. Both giant flying squirrels are endemic subspecies to Taiwan and are sympatric in much of their range. In the phylogenetic analyses, we included 35 specimens of P. alborufus lena collected from 20 localities and five specimens with unknown sampling localities. Also, we phylogenetically examined 32 specimens of P. philippensis grandis from 18 localities and three specimens with unknown sampling localities. We identified 36 haplotypes of P. alborufus lena and 33 haplotypes of P. philippensis grandis. Although we did not recognize major phylogroups, we found several minor phylogroups in both subspecies, suggesting similar evolutionary histories. Phylogeographical and demographic tests showed distributions of these two subspecies expanded into coniferous and mixed forests that developed during glaciation in Taiwan's lowlands and middle lands. This suggests that these two Petaurista subspecies shifted elevation from mountainous areas to lowlands during glaciation. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 404–419.     

The Hill reaction and oxygen uptake in isolated pine chloroplasts

1. The Hill reaction and oxygen uptake in chloroplasts preparedfrom pine leaves were studied. Pine chloroplasts active forthe Hill reaction were isolated from mature leaves in the presenceof 25% PEG in the isolation buffer. Time courses of the Hillreaction in chloroplasts isolated from leaves at different seasonsdiffered. In chloroplasts isolated in the autumn, Hill activitydecreased rapidly with illumination time. This rapid decreaseof Hill activity was inferred to result from concomitant productionof some inhibitory substance(s) during the Hill reaction.
2. Theprotective effect of PEG on inactivation by aging of pinechloroplastswas found. In the presence of PEG, chloroplastswere stabilizedand Hill activity was maintained even afterstorage for 26 hr;whereas, in the absence of PEG inactivationby aging proceededrapidly and oxygen uptake occurred after20 hr.
3. Chloroplastsisolated without PEG had no ability of the Hillreaction; but,inversely showed pronounced oxygen uptake. Oxygenuptake wasalso observed in aged or DCMU-inhibited chloroplasts.The presenceof benzoquinone strongly suppressed oxygen uptake.

¹ Present address: Laboratory of Biology and Chemistry, Universityof Naval Architecture of Nagasaki, Nagasaki, Japan. (Received January 27, 1971; )     

Inhibition of Bacterial DNA Replication by 6-(<Emphasis Type="Italic">p</Emphasis>-Hydroxyphenylazo)-uracil

THE semi-conservative replication of DNA of Gram-positive bacteria is specifically inhibited by 6-(p-hydroxyphenyIazo)-uracil (HPUra; obtained from ICI) in an apparently novel mechanism^1–4. We have attempted to characterize the HPUra-sensitive site in replication using in vitro preparations of drug-sensitive bacteria. In particulate and soluble preparations of sensitive bacteria, however, HPUra at high concentration does not significantly inhibit polymerization of deoxyribonucleotides^2,4. Since these systems may not accurately represent the process of DNA replication as it occurs in vivo, we have examined the effect of HPUra on a more suitable, toluene-treated preparation of Bacillus subtilis described by Matsushita et al.⁵. In this preparation, DNA replication is ATP-dependent, utilizes deoxyribonucleotides to give biologically active DNA, semi-conservatively and sequentially in the proper gene order. HPUra can inhibit DNA replication by this system. We describe here the characteristics of HPUra inhibition and the conditions necessary for it to occur.     

Cytoplasm Rescues an Arrhythmic Mutant on the Circadian Rhythm of Mating Reactivity in Paramecium bursaria

Cells of an unusual Paramecium bursaria stock (Sj2) expressed rhythmic mating reactivity in a light/dark cycle (LD) and under continuous illumination (LL). When placed in continuous darkness (DD), did not show rhythmicity but rather demonstrated a continuous high mating reactivity. However, mating reactivity was reduced following exposure to a 6-h light pulse interrupting the DD, and then recovered to its former condition. Genetic analysis showed the arrhythmicity in DD to be a dominant character inherited in a Mendelian ratio. On the other hand, a clone (MCIw) that did not show the rhythmicity in either DD or LL was isolated from the parent stock Sj2w following a 5-h treatment with 2 μg/ml nitrosoguanidine (MNNG). The MCIw cells expressed weak rhythmicity in LD, but were insensitive to a 6-h light pulse in DD. The arrhythmicity in LL was inherited cytoplasmically. In addition to this, rhythmicity in LL could be recovered by injection of cytoplasm from the wild-type cell when the recipient cell was homozygous for the wild-type nuclear gene (+/+). The cytoplasmic components or factors are assumed to control the functional circadian system and genetically determine the rhythmicity of mating reactivity.