ワダン×アゼトウナの雑種およびその逆交雑による雑種についての細胞学的観察を行った。体細胞染色体数はいずれも10であった。
交雑の容易なことおよび花粉稔性や痩果形成率などから, ワダンとアゼトウナとが自然状態において独立性を保っているのは, 地理的隔離に原因するものと考えられた。
減数分裂では一般に複糸期には多価染色体や多連染色体が多く見られるが分裂の進むにつれて解消して中期以後の分裂はほとんど正常に行なわれた。中期までわずかに残存する残余がここでも見出された。
属間雑種のワダン×ヤクシソウのF₁ F₂以後と比較した結果は, F₂以後のと非常に類似していることが観察された。

抄録全体を表示

スイバ (Rumex Acetosa) の花粉細胞の減數分裂に於て, 6個の二價染色體と1個の三連性染色體とが觀察される。二價染色體の染色體及びキアズマ行動は正常で末端化は完全である。
三連性染色體は前期に於て三放射状をなし, X 染色體の片腕の端部が Y₁ 染色體の長い腕とし, 他方の腕の端部が Y₂ 染色體の長い腕とし, Y₁ と Y₂ 染色體の短い腕は相互に端部でする。した部分にはキアズマを作る。キアズマ説に從へばキアズマは乘違の結果であるから, 此植物の性染色體にも乘違のあることを示唆する。

抄録全体を表示

T. Timopheevi (AAGG) と Ae. squarrosa 同質四倍体 (DDDD) との交雑を行なって6個体の F₁ (AGDD) を得た。この F₁ の中5個体は 2n=28で両親の配偶子染色体数の和に等しいが, 残る1個体は2n=29で1本だけ多い (AGDD+1)。
2n=28の F₁ の染色体は70.3%で PMC で6～7, 29.7%で8～10の二価染色体がかぞえられた。同時に4.1%の PMC で 0～2_III と0.2%で 0～1_IV の多価染色体もみられた。1細胞あたりの平均は 0.0016_IV+0.0428_III+7.2476_II+13.37_I である (第1, 2表)。
この F₁ のゲノム構成により最高の 10_II のうち 7_II は 4x-Ae. squarrosa の同親 (D-D) であることは明らかであるから, のこる 3_II は T. Timopheevi の同親 (A-G) でなければならない。型の頻度から D-D を除いて AG ゲノム間の量を計算すれば5個体平均4.71%で (第2表), これはすてに報ぜられた Emmer コムギの AB ゲノム間のそれ(木原1936, 近藤•釜野井1955～'58) に比べていくらか高い (第3表)。
多価染色体について三価は D-D のに A または G の1～2染色体が, 四価は D-D にそれと部分相同な A と G の染色体がして形成されたと思われる。
2n=29 F₁ の結果は第4表に示された。染色体の状態から, 1個余計な染色体は D ゲノムに属すると思われ, 4x-Ae. squarrosa に生じた DD+1 配偶子に T. Timopheevi の AG 配偶子が結合した結果てあろう。この個体の AG ゲノム間のは2n=28の F₁ と大差はない。
この実験を行なうにあたり多大な便宜を与えられ, 終始指導くださった中島吾一教授にあつく御礼申し上げる。

抄録全体を表示

相同染色体の不の頻度は, 染色体の長さに逆比例的に増加する (第1表)。染色体構成がひじようにヘテロなオオバナノエンレイソウの様似個体群からとつた1個体は, 上にのべた染色体の長さと不の間の一定の関係を示さないものであつた (第2～3表)。オオバナノエンレイソウの染色体には著しい構造変異があることが退色反応によつて確められている (第4表)。これらの構造変異は, 相同染色体のに種々な影響を与えるものと考えられる。この不の現象から個体群研究をすすめることは, 染色体の形態からの個体群分析の裏づけとしてもひじように興味ぶかいものと考えられる。

抄録全体を表示

In the present paper a theoretical consideration was made on the problems of differentiation and homology-relationship of the genom. Though tentatively the followings were concluded.
(1) In two genoms which are in 'intimate homology', the chromosome pairing is nearly complete, the modal class of number of pairing per nucleus corresponding to the basic chromosome number, n (Fig. 1, a), while in the ease of 'remote homology' the number of pairing is considerably variable, the modal class being 0 (Fig. 1, b). A good example of these extreme pairing ways is found in Trillium Hague (3n=15, K₁K₂T). The mode of pairing between K₁ and K₂ represents intimate homology and that between (K₁+K₂) and T remote one (Fig. 1, the ordinate indicates frequency of PMCs in percentage and the coordinate number or pairing per nucleus. cf. Haga 1937 and Tables 1-2).
(2) As a general rule it will be stated that the increase in the degree of genetic differentiation decreases the quantity of pairing proportionally to the grade or quantity of the differentiation. The relative value of the quantity of genetic differentiation will be then expressed by the quantity of pairing which will be adequately given by the following percentage index : 100× (Total number of pairing observed) /n× (Total number of PMCs observed).
Theoretically, we can expect all values of the index ranging from 0 to 100. Values of the two modes of pairing. in Trillium Hague were 95.7 for K₁-K₂ and and 5.6 for (K₁+K₂) -T, respectively, the former showing the intimate relation and the latter the remote one (Fig. 1, these values are indicated in italics beside the polygons). A more or less continuous variation in this value is evident in a series of diploid hybrids (2n=14) of Aegilops and Triticum (Fig. 2, the ordination and indication of the value are the same as in Figure 1. cf. Table 3). An interesting fact in the present case is that the decrease in quantity of pairing is accompanied by the transposition of the mode of frequency distribution in the direction from the intimate to the remote relation. The most continuous range of variation is obvious in a series of various diploid hybrids (2n=26) in Gossypium. The mean number of bivalents per nucleus shows a complete series from 13 to 2 (v. Skovsted 1937), The pairing relation in the inter- and intra-generic hybrids (2n=14) of Aegilops, Triticum. and Haynaldia is like-wise very suggestive for the present considerations (Fig. 3, only the maximum numbers of bivalents per nucleus are shown after the data compiled by Kihara 1937).
(3) The above considerations, will support the inference that : genetic differentiations will express, though superficially, a property of a continuous system. Thus homology is naturally the relation between any two of the genoms differentiated variously in a continuous system. In other words all the relations are included in the term 'homology', which ranges however in quantity of pairing from 0 to 100. Thus it is probable that 'homologous' or 'non-homologous' relation in the cytological sense implys nothing else intonate or remote relation respectively. Theoretically, only the 'identical' relationship-equality in quality, quantity and arrangement of all genes-may be absolute. This consideration naturally leads to the nullification of the critical boundary between auto- and allo-polyploidy.
(4) Certain differentiation as a whole of two or more sub-genoms in an allopolyploid would eventually lead to the formation of a new genom, which is no longer indivisible into the ancestral genoms. The new genom is polyploid in chromosome number but functionally diploid.. In the light of the recent knowledge it seems quite probable that the secondary polyploidy is an evolutional product. Then a genom has a potentiality to give rise to a non-pol

抄録全体を表示

Initiation of ColE1 plasmid replication requires hybridization of the primer transcript (RNA II) to the template DNA at the replication origin. The hybridization is inhibited by binding of another RNA, RNA I, to RNA II. This binding, which occurs in the nonessential region proximal to the 5'-end of RNA II, alters the secondary structure of RNA II even in the region far downstream of the segment where RNA I binds. Similar functional and Structural alterations of RNA II are caused by a single-base change within the nonessential region. By forming an alternative structure, the dispensable region affects folding of a downstream region, and thus participates in the regulation of DNA replication.

抄録全体を表示

目的：インプラントは口腔機能の回復に寄与するが，歯根膜の欠如したインプラントの挙動は，インプラント

歯に影響を与える可能性がある．本研究の目的はインプラント長期経過症例の歯喪失に関連する因子の検討である．

方法：2005年1月から2008年1月に臼歯部に上部構造を装着し，10年以上メインテナンスを継続した患者のうち，

が天然歯もしくは天然歯支台固定性補綴装置の患者を対象とした．

調査項目1として，インプラント，インプラント補綴装置，インプラント

歯の喪失の有無，調査項目2として，歯の位置（上顎，下顎），歯髄の有無，歯周炎の既往，下顎角の大きさを調査し，二項ロジスティック回帰分析を行った（p＜0.01）．

結果：調査者数は358名（男性121名，女性237名，平均年齢65.8歳），インプラント数は700本（上顎397本／201名，下顎303本／157名），インプラント補綴装置数は358装置，インプラント

歯数は667本だった．

インプラント，インプラント補綴装置，インプラントの

歯の喪失は，10本／8名，0装置／0名，62本／32名だった．統計学的有意差は，患者レベルでは，歯周炎の既往，下顎角の大きさで，インプラントレベルでは，歯の歯髄の有無，歯周炎の既往，下顎角の大きさで認められた．

結論：インプラント

歯へ影響する要因として，歯の歯髄の有無，歯周炎の既往，下顎角の大きさが挙げられ，歯の位置（上顎，下顎）は影響しないと考えられた．

抄録全体を表示

In this paper, first we formulate a kissing hairpin between two RNA sequences as RNA tertiary structures kissing two hairpin loops for every RNA sequence. Then, we design the method of finding all of the maximal kissing hairpins between two RNA sequences, where a kissing hairpin is maximal if the length of its kissing part is maximal. Finally, by connecting maximal kissing hairpins with the same kissing part between two RNA segments, we give experimental results of finding maximal kissing hairpins through 8 RNA segments in influenza A (H3N2) viruses.

抄録全体を表示

In dentistry, the opposing relations between the upper and lower teeth during contact, which is referred to as occlusion, are evaluated chiefly by the location and/or total area of their contact portions. Considering the amount of force applied to the teeth during chewing, however, the proximity between the opposing surfaces as a whole should also be evaluated. In order to evaluate the relations of opposing teeth, including both contact and clearance, the distance transformation was applied, in which any surface point was mapped into the distance between that point and its opposing surface. That distance and its distribution on the surface are referred to as the interocclusal distance and the distance map, respectively. This map provides a closed surface-region where the interocclusal distance is less than or equal to xmm, denoted as R(x). This region can be interpreted as a generalization of contact region R(0) by the interocclusal distance. The proximity can be evaluated by the area of R(x), denoted as s(x)mm^2, which decreases monotonously as the two surfaces approach each other. To verify the validity of s(x) for the occlusal analysis, it was applied to that during lateral excursions. The occlusal surfaces of the upper and lower first molars were digitized by a laser scanner, and the jaw movements were measured in 6 degrees of freedom. The combination of these measurements provides any positional relation between the opposing surfaces during lateral excursions. Proximity s(x) of the upper first molar was computed at various occlusal positions, where the incisal point was less than or equal to 2.0mm from its location in the intercuspal position (ICP). Proximity s(x) relative to that in the ICP, referred to as the relative proximity, was compared on the working and non-working sides. For s(0.3), the difference between the two sides was not significant statistically on the relative proximity in all the lateral positions, suggesting that the portions relatively close to the opposing surface remained even on the non-working side. For s(2.0), however, the relative proximity on the working side was on average larger than that on the non-working side, as was expected. These results revealed that proximity {s(x)|x≧0} considerably reflected the opposing relation of the two surfaces as a whole.

抄録全体を表示

Ch. indicum var. hexaploid (2n=54)×Ch. lavandulaefolium (2n=18) においてそれを種々の栽培条件下で行い, Ch. indicum var. hexaploid の半数体植物(2n=27)を作ることに成功した. なおこの交雑においては染色体数の増加したF₁ (2n=45)をも生じた. この二種類の子孫における細胞学的研究を行つた結果, 半数体において9_IIIその他, 雑種において多数の五価染色体を含むが観察された. 又二種類の子孫の何れにおいても, ゲノム数より多い多価染色体が観察された. この観察結果から Ch. indicum var. hexaploid が同質的六倍体で, 且つそのゲノムがすべてCh. lavandulaefolium 田中: Ch. indicum var. hexaploid× Ch. lavandulaefolium の半数体と雑種 23のゲノムと同質的であることが明らかとなつた. これらの結果と下斗米及び竹本氏 (1936, 1938, 1939) による核型の研究結果とから, Ch. lavandulaefolium のゲノムは A A で表すとCh. indicum のゲノムは A A A' A', Ch. indicum var. hexaploid のゲノムはで AAAAA'A' 示される.

抄録全体を表示