All issues
Successor
Volume 26 (1951)
- Issue 5-6 Pages 157-
- Issue 3-4 Pages 69-
- Issue 1-2 Pages 1-
Volume 26, Issue 5-6
Displaying 1-8 of 8 articles from this issue
- |<
- <
- 1
- >
- >|
-
Humihiko Ono1951 Volume 26 Issue 5-6 Pages 157-173
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS1. Many F4 individuals of Paraixeris denticulata×Crepidiastrum platyphyllum were studied both morphologically and cytologically with special reference to their fertility.
2. In many individuals the somatic chromosome number was 10. Only three had 11 chromosomes. The mechanism of preservation of the chromosome number was supposed to be well equipped.
3. In the root-tips of four individuals, polyploid cells were observed beside the diploid ones. The tendency of chromosome doubling in heterozygocity seems not to be unusual.
4. In many individuals new types of chromosomes were observed. This seems to be a similar phenomenon to the novation of Navashin, and seems to be caused by semihomologous crossing-over.
5. In the meiotic division some individuals had only bivalents. But in the others multivalents or prematurely separating bivalents were observed in abundance. The forms and the components of multivalents were quite variable. In general more multivalents were observed in the earlier diakinesis than in the metaphase. From the observations of meiosis the following conclusions have been drawn.
a) Winge's hypothesis of systematic importance of polymery may be applied also to the explanation of chromosome pairing.
b) A hypothesis of residual affinity in pairing advanced by the present author explains adequately the various configurations observed.
c) The secondary association may be a manifestation of residual affinity.
6. There were little correlation between the pollen fertility and the rate of achene setting (r=0.20). The low pollen fertility was correlated with the multivalents and the low rate of achene setting with the prematurely separating bivalents. It was supposed that the mode of meiosis is different in male and in female, and that the pairing power is a little stronger in female.
7. The fertility was much restored in F4 in spite of an increase of meiotic irregularities. This seems to be caused mainly by the restoration of cytoplasm-nucleus relations. It was suggested that the alteration of cytoplasm in accordance with the foreign nucleus will be taken place gradually both in somatic and germ cells.
8. The inclination of F4 population to the type of Paraixeris parent was supposed to be the consequence of selection pressure of the cultural conditions. It is remarkable that new intermediate forms with higher fertilities have appeared.View full abstractDownload PDF (1733K) -
Moto Kimura1951 Volume 26 Issue 5-6 Pages 175-184
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS1) The progress in the chiasma-type theory and the studies of tetrad analyses in lower plants have made clear that each locus in a given chromosome has its specific frequency of the equational separation at the first division of meiosis.
But some additional statistical theories whould be necessary to make the state of the chromosome reduction clearer.
In this paper following two problems were dealt with:
(a) To obtain the frequency distribution of the length of pre- and post- reductional segments in the chromosome tetrads.
(b) To calculate the mean length of such segments for some genetically well studied chromosomes.
2) For telomitic chromosomes with genetical length of 100l units and without chromatid interference, the frequency distribution of the length (ξ) of post-reductional segments is given by the following formula, if multiple cross-overs are negligible in frequency.
Φ(ξ)=φ'(ξ)+2φ'(l-ξ)-(l-ξ)φ”.ξ)-1,
where φ(ξ) is the recombination probability between two genes which are 100ξ units apart.
For X-chromosome of Drosophila melanogaster (70 units in length), the above formula becomes
Φ(ξ)= cos2ξ+2cos(1.4-2ξ)+(1.4-2ξ)sin2ξ-1,
the graph of which is shown in Fig. 2.
3) Taking the chromosome as the abscissa and assuming that f(x) represents the probability of the post-reduction of a point x, then the mean length of post-reductional parts of the chromosome or chromosomal segment ab is
L=∫baf(x)dx,
which equals the area bounded by the curve Y=f(x), the axis of x and the ordina_??_es x=a, and x=b (cf. Fig. 6).
4) The proportions (in percent) of the length of pre- and post-reductional segments calculated by the above method are listed for some genetically well studied chromosomes as follows:
l-L/l L/l
Neurospora crassa, sex-chromosome 66.5% 33.5%
Sphaerocarpus Donnellii,
squamifera-chromosome 52.2% 47.8%
Drosophila melanogaster,
X-chromosome {46% 54% 48%_??_ 52%_??_
II-chromosome 48% 52%
Drosophila virilis,
X-chromosome {40.7% 59.3% 40.0%_??_ 60.0%_??_
In this table l-L/l and L/l represent respectively the proportion of pre- and post-reductional segments and the values with the asterisks were calculated on the cytological maps, while other values were all calculated on the genetical maps.View full abstractDownload PDF (5392K) -
I. Gene analysisToyokazu Yamada, Seiji Fujiyoshi1951 Volume 26 Issue 5-6 Pages 185-194
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe inheritance of the types of young plants which are prominent at the younger stage of development in wheat has been studied, with particular reference to some of the adult characters, in 4 successive generations from F1 to F4 of Hokuriku No. 13 with Saitama No. 27 crossing from 1938 to 1941.
The types of young plants were classified into five or six classes, T1-T5 or T6, from prostrate to erect by observation (c. f. Fig. 1).
The young plant type was intermediate in F1 between both parents. The distribution curve on the plant types of 390 F2 plants fairly resembled a normal curve as shown in Table 1. In 110 F3 lines descended from each class in F2 generation, various mean values (Type-values), which express the types of young plants in each line numerically, were observed as shown in Table 3. The result may be explained by two heteromeric major genes E1 and E2, which are imperfect in dominancy (c. f. Table 4-6 and Fig. 2).
In F4 generation, however, 17 families derived from each of 9 genotypes in F3 generation were grown, and the segregation was found more complicated than in F3 (c. f. Table 7). From this result it was assumed that the third gene E3, the effect of which being considerably weaker than the former two, should concern to the genic constitution of the young plant types. All F4 lines were successfully classified into 27 genotypes, which should theoretically result from the segregation of the three gene pairs (c. f. Table 8-10).
It may be concluded, therefore, that the types of young plants are controlled by three major heteromeries.View full abstractDownload PDF (1623K) -
Jin-Ichi Kitada1951 Volume 26 Issue 5-6 Pages 195-197
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSSeasonal spermatogenetic changes were observed in the testis of a lizard, Eumeces latiscutatus, common in Japan-Hondo. During the months of April, May and early June, all spermatozoa are eliminated from the seminal tubules. Spermatogonial divisions occur in May and June. Primary and secondary spermatocytes and maturation divisions appear through July and August. Spermioteleosis is practically completed during from late November to December. During hibernation, there is no spermatogenetic activity in the testis.View full abstractDownload PDF (318K) -
Cytogenetical studies of triple hybrid from F1 Triticum turgidum×Secale cereale and Triticum vulgareII. B. Maturation division of pollen mother cells in triple F1 plant having 2n=44 chromosomesGoichi Nakajima1951 Volume 26 Issue 5-6 Pages 199-202
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS1. A cytological investigation on the Triticum-Secale triple F1 hybrid having 2n=44 chromosomes was carried out in maturation division of P. M. C. s.
2. The triple F1 hybrid having 2n=44 chromosomes was raised from primary hybrid T. turgidum×S. cereale F1, the chromosomes of which being 2n=23, with T. vulgare.
3. 21 chromosomes in the 44 ones seem to have come from T. vulgare as the pollen parent and the remaining 23 chromosomes from F1 plant of primary hybrid as the mother parent.
4. The number of bivalents and univalents in one P. M. C. at metaphase of first maturation division has shown to vary from 4 to 12 in the former case and from 20 to 36 in the latter one respectively.
5. The constitution of genoms, according to the result obtained in the present investigation on the maturation division in P. M. C. s of this triple F1 hybrid, will be represented by the following formula: AB (T. turgidum)+(R+2) (S. cereale)+ABD(T. vulgare).View full abstractDownload PDF (369K) -
Goichi Nakajima1951 Volume 26 Issue 5-6 Pages 203-209
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSCytogenetical studies on the amphidiploids raised from interspecific hybrids of Quamoclit by the colchicine treatment have been carried out by the author.
In amphidiploids, the length of guard cells of stomata is larger than that of the parents, and about as large as that of Q. Sloteri (Table 3).
Further, the size of flowers is larger than that of the parents (Fig. 2).
In F1 plants, abortive pollen grains were observed in exceedingly higher percentage than in amphidiploids (Table 5). The size of pollen grains in amphidiploids is larger than that of the F1 (Table 6), i. e., nearly equal in size to the Q. Sloteri's.
F1 plants were completely sterile, but the amphidiploids were fertile, though the percentage is low (16.04%).
The fruits of amphidiploids were morphologically intermediate between parents of them.
The weight of 1000 seeds of Q. coccinea, Q, coccinea var. hederifolia and Q. pennata were 11.6, 14.2 and 16.5grs respectively. And that of the amphidiploids from hybrid I and II were 30.1 and 32.6grs, that is nearly equal to the seed weight of Q. Sloteri, 31.6grs.
The number of somatic chromosomes were 30 in Q. pennata (Fig. 7). 28 in both Q. coccinea and Q. coccinea var. hederifolia (Figs. 5 and 6). In F1 plants of Q. coccinea×Q. pennata and Q. coccinea var. hederifolia×Q. pennata, the number of chromosomes was 2n=29 (Figs. 8 and 9) in both cases. The number of chromosomes of amphidiploids raised from hybrid I (Q. coccinea×Q. pennata) and II (Q. coccinea var. hederifolia×Q. pennata) was 2n=58 in both combinations (Fig. 10). These numbers correspond to double the somatic number of F1 of hybrids I and II, viz. equal to the number of Q. Sloteri's chromosomes 2n=58 (Fig. 11).View full abstractDownload PDF (1424K) -
S. Matsumura1951 Volume 26 Issue 5-6 Pages 211-218
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (17998K) -
S. Imamura1951 Volume 26 Issue 5-6 Pages 219-222
Published: 1951
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (596K)
- |<
- <
- 1
- >
- >|