Abstract
1. Seven varieties of rice plants have been cytologically examined. The chromosome number in each is determined as 12 haploid, 24 diploid. Satellites and secondary constrictions are not found in the chromosomes.2. In the somatic prophase a pair of chromosomes with terminal knob-like bodies remain attached by the knob to two Small nucleoli or one large nucleolus which results by the fusion of the two. These knobs must be concerned in the growth of the telophase nucleoli.3. The resting nucleus of the pollen mother-cells generally has a single nucleolus with no crystalline bodies.4. The leptotene thread is split like the somatic early prophase chromosomes, the two chromonemata being closely twisted about each other.5. During the heterotypic prophases the nucleoli, one or two in number, remain closely connected with a particular pair of chromosomes at one end (referred to as the nucleolar body) from the leptotene stage until the nucleolus disappears completely at metaphase.6. During synizesis the nucleolus in some of the nuclei of the varieties studied produces a bud, which grows until the two nucleoli attain the Same size at early diakinesis by transfer of material from the larger to the smaller.7. Comparison of six varieties of rice shows no difference in the size of the nuclei and nucleolar contents. But it shows a significant difference in the size of the nuclear diameter in those cells with one nucleolus at diakinesis and with two (Table 1). This is correlated with the differences in the size of the nucleolar diameter when one nucleolus or two are present at diakinesis. Only the larger nucleoli (which are present in the larger nuclei) bud, and the “budding” takes place after the maximum size of the nucleolus is reached.8. Budding of the nucleolus may be due to the relative increase of the nucleolar material within the mother nucleolus or it may be an artefact produced by the treatment. When budding takes place it is always at the point of attachment of the terminal chromosome knob.9. The method of chromosome pairing is parasynaptic, pairing commencing at the ends of the chromosomes. Variation in size and shape of the 12 bivalent chromosomes is found in early diakinesis, one larger twisted pair being particularly noticeable.10. From resting stage until early diakinesis there is an increase in the size of the nucleolus, followed by a gradual decrease from late diakinesis with the gradual condensation of the chromosomes until the time of its complete dissolution at metaphase.11. It is concluded that the nucleolus contributes matrix substances (not chromatin) indirectly to all the chromosomes, which is carried over by metaphase and anaphase chromosomes, and a definite nucleolus is organized at telophase from this substance under the influence of the nucleolar body present an the end of one chromosome of the haploid complement. Trivalent and univalent chromosomes are sometimes found at diakinesis in certain Japanese varieties.12. The phenomena of cytomyxis, pollen mother-cell fusion, binucleate and tetraploid pullen mother-cells and failure of cytokinesis during meiotic divisions of some of the microsporocytes, are described. As the result of these aberrations, diploid gametes are formed, which will account for the origin of triploid and tetraploid plants of rice.13. The origin of the nucleolus is discussed and its relation to the nucleolar body; also the possible rôle of the nucleolus in inheritance.14. It is emphasized that further studies of a biochemical nature are required before definite conclusions may be drawn as to the relationship between the matrix substance of the ehromosomes and the nucleolus.This work was carried out in the Botanical Department of King's College, University of London. The author wishes to express his indebtedness and sincerest gratitude to Professor R. Ruggles Gates, under whose supervision this work was done
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Claims 18
Claim · model-written summary
Seven rice varieties had 12 haploid and 24 diploid chromosomes.
- Taxon
- Rice
Oryza sativat0 - Outcome
- The chromosome number in each is determined as 12 haploid, 24 diploid.e0
- Value
- 12 haploid, 24 diploide0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The chromosome number in each is determined as 12 haploid, 24 diploid.”
t0“Rice”
Claim · model-written summary
Satellites and secondary constrictions were absent from the rice chromosomes.
- Taxon
- RiceOryza sativat0
- Outcome
- Satellites and secondary constrictions are not found in the chromosomes.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Satellites and secondary constrictions are not found in the chromosomes.”
t0“Rice”
Claim · model-written summary
A chromosome pair with terminal knobs remained attached to nucleoli in somatic prophase.
- Taxon
- RiceOryza sativat0
- Outcome
- In the somatic prophase a pair of chromosomes with terminal knob-like bodies remain attached by the knob to two Small nucleoli or one large nucleolus which results by the fusion of the two.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the somatic prophase a pair of chromosomes with terminal knob-like bodies remain attached by the knob to two Small nucleoli or one large nucleolus which results by the fusion of the two.”
t0“Rice”
Claim · model-written summary
Resting pollen mother-cell nuclei generally had one nucleolus without crystalline bodies.
- Taxon
- RiceOryza sativat0
- Outcome
- The resting nucleus of the pollen mother-cells generally has a single nucleolus with no crystalline bodies.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The resting nucleus of the pollen mother-cells generally has a single nucleolus with no crystalline bodies.”
t0“Rice”
Claim · model-written summary
The leptotene thread was split into two closely twisted chromonemata.
- Taxon
- RiceOryza sativat0
- Outcome
- The leptotene thread is split like the somatic early prophase chromosomes, the two chromonemata being closely twisted about each other.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The leptotene thread is split like the somatic early prophase chromosomes, the two chromonemata being closely twisted about each other.”
t0“Rice”
Claim · model-written summary
Nucleoli stayed connected to a chromosome pair from leptotene until metaphase.
- Taxon
- RiceOryza sativat0
- Outcome
- the nucleoli, one or two in number, remain closely connected with a particular pair of chromosomes at one end (referred to as the nucleolar body) from the leptotene stage until the nucleolus disappears completely at metaphase.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the nucleoli, one or two in number, remain closely connected with a particular pair of chromosomes at one end (referred to as the nucleolar body) from the leptotene stage until the nucleolus disappears completely at metaphase.”
t0“Rice”
Claim · model-written summary
Some nucleoli budded during synizesis, reaching equal size at early diakinesis.
- Taxon
- RiceOryza sativat0
- Outcome
- During synizesis the nucleolus in some of the nuclei of the varieties studied produces a bud, which grows until the two nucleoli attain the Same size at early diakinesis by transfer of material from the larger to the smaller.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During synizesis the nucleolus in some of the nuclei of the varieties studied produces a bud, which grows until the two nucleoli attain the Same size at early diakinesis by transfer of material from the larger to the smaller.”
t0“Rice”
Claim · model-written summary
Six rice varieties did not differ in nuclear and nucleolar size.
- Taxon
- RiceOryza sativat0
- Outcome
- Comparison of six varieties of rice shows no difference in the size of the nuclei and nucleolar contents.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of six varieties of rice shows no difference in the size of the nuclei and nucleolar contents.”
t0“Rice”
Claim · model-written summary
Nuclear diameter differed significantly between diakinesis cells with one and two nucleoli.
- Taxon
- RiceOryza sativat0
- Outcome
- it shows a significant difference in the size of the nuclear diameter in those cells with one nucleolus at diakinesis and with twoe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it shows a significant difference in the size of the nuclear diameter in those cells with one nucleolus at diakinesis and with two”
t0“Rice”
Claim · model-written summary
Only larger nucleoli budded after reaching maximum size.
- Taxon
- RiceOryza sativat0
- Outcome
- Only the larger nucleoli (which are present in the larger nuclei) bud, and the “budding” takes place after the maximum size of the nucleolus is reached.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only the larger nucleoli (which are present in the larger nuclei) bud, and the “budding” takes place after the maximum size of the nucleolus is reached.”
t0“Rice”
Claim · model-written summary
Nucleolar budding occurred at the terminal chromosome knob attachment.
- Taxon
- RiceOryza sativat0
- Outcome
- When budding takes place it is always at the point of attachment of the terminal chromosome knob.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When budding takes place it is always at the point of attachment of the terminal chromosome knob.”
t0“Rice”
Claim · model-written summary
Chromosome pairing was parasynaptic and began at chromosome ends.
- Taxon
- RiceOryza sativat0
- Outcome
- The method of chromosome pairing is parasynaptic, pairing commencing at the ends of the chromosomes.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The method of chromosome pairing is parasynaptic, pairing commencing at the ends of the chromosomes.”
t0“Rice”
Claim · model-written summary
The twelve bivalents varied in size and shape in early diakinesis.
- Taxon
- RiceOryza sativat0
- Outcome
- Variation in size and shape of the 12 bivalent chromosomes is found in early diakinesis, one larger twisted pair being particularly noticeable.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Variation in size and shape of the 12 bivalent chromosomes is found in early diakinesis, one larger twisted pair being particularly noticeable.”
t0“Rice”
Claim · model-written summary
Nucleolus size increased to early diakinesis and then declined until metaphase.
- Taxon
- RiceOryza sativat0
- Outcome
- From resting stage until early diakinesis there is an increase in the size of the nucleolus, followed by a gradual decrease from late diakinesis with the gradual condensation of the chromosomes until the time of its complete dissolution at metaphase.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“From resting stage until early diakinesis there is an increase in the size of the nucleolus, followed by a gradual decrease from late diakinesis with the gradual condensation of the chromosomes until the time of its complete dissolution at metaphase.”
t0“Rice”
Claim · model-written summary
Trivalent and univalent chromosomes occurred in some Japanese varieties.
- Taxon
- RiceOryza sativat0
- Outcome
- Trivalent and univalent chromosomes are sometimes found at diakinesis in certain Japanese varieties.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Trivalent and univalent chromosomes are sometimes found at diakinesis in certain Japanese varieties.”
t0“Rice”
Claim · model-written summary
Cytomyxis, cell fusion, binucleate and tetraploid pollen mother cells, and failed cytokinesis occurred.
- Taxon
- RiceOryza sativat0
- Outcome
- The phenomena of cytomyxis, pollen mother-cell fusion, binucleate and tetraploid pullen mother-cells and failure of cytokinesis during meiotic divisions of some of the microsporocytes, are described.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The phenomena of cytomyxis, pollen mother-cell fusion, binucleate and tetraploid pullen mother-cells and failure of cytokinesis during meiotic divisions of some of the microsporocytes, are described.”
t0“Rice”
Claim · model-written summary
These meiotic aberrations produced diploid gametes.
- Taxon
- RiceOryza sativat0
- Outcome
- As the result of these aberrations, diploid gametes are formed, which will account for the origin of triploid and tetraploid plants of rice.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“As the result of these aberrations, diploid gametes are formed, which will account for the origin of triploid and tetraploid plants of rice.”
t0“Rice”
Claim · model-written summary
The authors concluded that nucleolar matrix substance contributes to chromosomes and reorganizes a nucleolus at telophase.
- Taxon
- RiceOryza sativat0
- Outcome
- It is concluded that the nucleolus contributes matrix substances (not chromatin) indirectly to all the chromosomes, which is carried over by metaphase and anaphase chromosomes, and a definite nucleolus is organized at telophase from this substance under the influence of the nucleolar body present an the end of one chromosome of the haploid complement.e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It is concluded that the nucleolus contributes matrix substances (not chromatin) indirectly to all the chromosomes, which is carried over by metaphase and anaphase chromosomes, and a definite nucleolus is organized at telophase from this substance under the influence of the nucleolar body present an the end of one chromosome of the haploid complement.”
t0“Rice”