Auxin-induced growth of tuber tissue of Jerusalem artichoke IV. Significance of gibberellin biosynthesis and basic proteins in chromatin in aging process

The role of endogenous gibberellin in the aging process preparatoryto auxin action of expanding cells was studied, using tissueslices excised from cold-stored Jerusalem artichoke tuber. CCC inhibited the auxin-induced expansion growth when addedto slices during the aging period. This inhibition was alleviatedby the simultaneous addition of gibberellic acid. The amountof gibberellin-like substances increased during the aging periodand this increase was suppressed by CCC. During the aging period, acid-soluble basic proteins in thechromatin fraction decreased in amount, and exogenous gibberellicacid enhanced the decrease. (Received October 30, 1967; )     

RIBONUCLEIC ACID METABOLISM AND CELL EXPANSION IN OAT COLEOPTILE

RNA metabolism in oat coleoptiles was studied using physiologicalresponses to 5-FU and actinomycin D; autoradiographic detectionof RNA and protein synthesis; and estimation of ribosomal concentrationby analytical ultracentrifugation. 5-FU failed to inhibit growthof either intact coleoptiles or isolated coleoptile segmentsbut completely blocked cell division in roots. Actinomycin Dmarkedly inhibited auxin-induced expansion of coleoptile segments.When supplied to isolated segments from coleoptiles of variouslengths the RNA precursors cytidine, adenine and adenosine allshowed weak incorporation into RNA of nuclei and in some cases,to a lesser extent, RNA of cytoplasm. IAA did not affect thisRNA synthesis but it was considerably reduced by actinomycinD. A proportion of the label incorporated from RNA precursorswas not removable with either RNase, PCA or hot TCA but wasextracted by trypsin. The amount of this spurious incorporationincreased with coleoptile age, as did the ability to incorporatelabelled amino acids. The concentration of both free and boundribosomes does not increase in growing coleoptiles and may evendecline. Free ribosomes decline markedly in fully grown coleoptileswhile the proportion of bound ribosomes increases. It is concludedthat young coleoptiles contain a full complement of ribosomesnecessary for subsequent growth but normal growth is dependenton continued production of an actinomycin D-sensitive messenger-typeRNA. No evidence for auxin mediation of RNA synthesis was found. ¹Present address: Laboratory of Cell Biology, Faculty of Science,Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka, Japan.     

POLYTENE CHROMOSOMES ISOLATED FROM NUCLEI OF TOKUNAGAYUSURIKA AKAMUSHI (DIPTERA, CHIRONOMIDAE): STRUCTURAL TRANSFORMATION CAUSED BY SALT, DETERGENT POLYANIONS AND ENZYMES

Polytene chromosomes of Tokunagayusurika akamushi (Chironomidae) were isolated from nuclei of the salivary glands. The isolated chromosomes retained their normal morphology, revealing bands by phase contrast microscopy.
Extensive structural transformations were observed when the isolated chromosomes were immersed in solutions of high salt concentration, polyanions (dextran sulfate and heparin), the ionic detergent SDS (0.01% or more) or enzymes. The morphological changes could be described in terms of combinations of the following characteristics: (1) reversible or irreversible changes, (2) expansion or no expansion, (3) disappearance of bands, and (4) appearance of new bands. The structural features of the transformed chromosomes are described.     

Further studies on the role of cell-wall-degrading enzymes in cell-wall loosening in oat coleoptiles

A fungal endo-ß-l,3-glucanase was compared with afungal exo-ß-1,3-glucanase with respect to their effectson elongation and cell-wall extensibility in oat coleoptilesegments. The exo-enzyme enhanced elongation and extensibilityof the cell wall. Its effect was not additive to the effectof indole-3-acetic acid when given together with the latter,at least during 3 hr of incubation. Endo-glucanase showed nosignificant effect on elongation and no interaction with theexo-enzyme. Auxin and exo-glucanase increased extensibilityof the cell wall. The exo-glucanase was separated by isoelectricfocusing. The two fractions which were separated and showedglucanase activity induced elongation and cell wall loosening. (Received March 16, 1970; )     

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.     

Control of Auxin-induced Stem Elongathn by the Epidermis

Segments of the 4th and 5th internodes of light-grown pea seedlings were used for the study of control of stem elongation. With 5th internodes, at low turgor as well as at water saturation auxin primarily appeared to cause a change in cell wall properties of the epidermis but it showed little effect on expansion af the inner tissue. This was confirmed by comparison of expansion between peeled and unpeeled segments, split tests and by measurements of stress-relaxation properties of the epidermal cell wall. Segments with the central part re-moved elongated well in response to auxin, but the isolated epidermis showed neither auxin-induced elongation nor cell wall loosening. A fungal β-1,3-glucanase appeared, at least partly, to have a similar effect as that of auxin on elongation, by changing cell wall properties of the epidermal cell wall. Peeled segments of 4th internodes expanded very little and auxin had little effect on their epidermal cell wall properties.     

Role of the epidermis in auxin-induced elongation of light-grown pea stem segments

1. Effects of auxin on elongation and cell wall properties werestudied using 5th internode segments of light-grown pea epicotyl.The results were:
2. The optimum concentration of 2,4-D for elongationinductionwas about 1 µg/ml, both for unpeeled and peeledsegments.
3. Using stress-relaxation analysis, mechanical propertiesof thecell wall were expressed by the parameters 1/₁, To andT_m. Unpeeledsegments were first treated with 2,4-D, then theepidermis waspeeled off. Parameters of the epidermal cell wallwere conspicuouslychanged by 2,4-D but those of the inner tissuewere not.
4. Actinomycin D and cycloheximide inhibited 2,4-D-inducedchangesin cell wall parameters, as well as in elongation, ofunpeeledsegments apd of the epidermis.
5. 2,4-D did not induceelongation of the isolated epidermis butpromoted that of peeledsegments. This promotion was smalleras compared with unpeeledsegments. 2,4-D did not significantlyinfluence the diffusionpressure deficit of peeled segmentsbut did increase their elasticand plastic extensibilities.
6. We conclude that auxin primarilyinduces cell wall looseningof the epidermis, most likely throughnucleic acid and proteinsynthesis.

¹ Present address: Biological Institute, Department of GeneralEducation, Nagoya City University, Mizuho-ku, Mizuho-cho, Nagoya467, Japan. (Received April 22, 1971; )     

Effects of Thioureas, Inhibitors of Melanogenesis, on Lens Transdifferentiation of Cultured Chicken Embryonic Retinal Pigment Cells

The effects of phenylthiourea (PTU) and its analogues on chick embryonic pigmented epithelial cells (PECs) in culture were studied to elucidate the correlation between inhibition of melanogenesis of PECs and enhancement of their transdifferentiation into lens cells.
Both 0.25–0.5 mM PTU and 0.1 mM alpha-naphthylthiourea (ANTU) effectively inhibited melanogenesis of PECs and stimulated their transdifferentiation into lens cells at the same time. Thiourea (TU) also inhibited melanogenesis at a much higher concentration (4 mM), but did not stimulate the lens transdifferentiation at all. Methylthiourea (MTU), on the other hand, did not inhibit melanogenesis, but stimulated the lens transdifferentiation. Testicular hyaluronidase effectively amplified the above-mentioned stimulating effects of thioureas without their altering optimum concentrations, although this enzyme itself never enhanced the lens transdifferentiation of PECs but suppressed their melanogenesis at a concentration of 100 U/ml medium, onward.
These results suggest that the suppression of melanogenesis of PECs by PTU or its analogues does not directly correlate with their transdifferentiation into lens cells. The possible mode of thiourea actions on the lens transdifferentiation of PECs cultured in vitro is discussed.     

AUXIN-INDUCED GROWTH OF TUBER TISSUE OF JERUSALEM ARTICHOKE: II. THE RELATION TO PROTEIN AND NUCLEIC ACID METABOLISM

The following results were obtained using tissue slices excisedfrom cold-stored Jerusalem artichoke tuber. 1. Increase in protein content of the tissue was small duringthe washing (i.e. "aging"), and great in the growth phase, particularlyin washed tissue. 2. RNA content of tissue increased during the growth periodsimilarly in non-growing tissue (in water) and actively growingtissue (in 2,4-D plus KIN). 3. Both RNA and DNA increased during the washing, the increasebeing greater in RNA than in DNA. This RNA increase was enhancedby gibberellic acid. 4. 2-Thiouracil, 8-azaguanine, puromycin, and mitomycin C givenat the washing inhibited the subsequent growth. The effect ofthese inhibitors was not significant when they were given inthe growth period. 5. Mitomycin C reduced the basophilia of nuclei and made themswell, as did deoxyribonuclease. 6. The effect of inhibitors of nucleic acid metabolism was reversedto some extent by gibberellic acid and by kinetin. 7. Chloramphenicol inhibited the growth strongly if given inthe growing period, but not so strongly if given during thewashing. 8. An autoradiographic study using ³H-cytidine suggested thatRNA is synthesized in nucleus during the period of washing andis transferred to cytoplasm via nucleolus. It is conjectured that the RNA synthesized during the agingis responsible for the expansion growth to be caused later byauxin or auxin plus kinetin. (Received September 4, 1965; )     

四种鹿属动物的线粒体DNA差异和系统进化关系研究

用聚合酶链反应 ,从水鹿、坡鹿、梅花鹿和马鹿等四种鹿属动物中分别扩增出线粒体DNA的细胞色素 b基因片段 ,并测定得到 367bp的碱基序列 ,它们之间的序列差异在 4 .0 9%～ 7.0 8%之间。用 NJ法、最大简约法和最大似然法进行分子系统进化树的构建和分析并得出 ,水鹿与坡鹿、梅花鹿和马鹿约在 2 4 0～ 2 80万年前分化的 ,梅花鹿和马鹿大约在 1 60万年前左右分化。