Abstract
Three plant species and one animal species have been subjected to cold treatment in order to determine whether or not the DNA content of the cells shows a reduction. The following conclusions have been drawn from this study:1. A decrease in the amount of DNA results from cold treatment in Trillium erectum and Trillium sessile which is observable both by microscopic observations and by spectrophotometric measurements. These two species show no noticeable decrease in mitotic processes when cold treated. Tradescantia edwardsiana, which has supernumerary chromosomes, shows a slight increase in DNA which is attributed to the suppression of mitotic activity. Chortophaga viridifasciata does not show any significant change in meiosis subsequent to pachytene, and there is a systematic halving of the quantity of DNA corresponding to the divisions in meiosis.2. There are at least two types of DNA present in Trillium erectum and Trillium sessile, a stable type associated with gene-bearing regions and a more labile type found in heterochromatic regions. The decrease of DNA caused by cold treatment appears to be due to a deficiency of this labile fraction of DNA.3. Cold treatment of chromosomes results in manifestations remarkably similar to effects from other physical and chemical agents, such as 5-aminouracil and an ultraviolet microbeam.4. The changes in quantity of DNA due to cold treatment occur only in selected plants having large heterochromatic regions and ones which are able to continue mitotic processes despite severe alteration of the environment. For these reasons, it is believed that reduction of DNA content as shown in this study does not invalidate the usefulness of the concept of constancy of DNA as currently advocated by Swift and others.
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Claims 5
Claim · model-written summary
Cold treatment decreased the amount of DNA in Trillium erectum and Trillium sessile.
- Taxon
- Trillium erectum and Trillium sessile
Trillium sessile
Trillium erectume1 - Treatment
- cold treatmente1
- Outcome
- amount of DNAe1
- Direction
- decreasee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“A decrease in the amount of DNA results from cold treatment in Trillium erectum and Trillium sessile”
Claim · model-written summary
Cold treatment slightly increased DNA in Tradescantia edwardsiana, attributed to suppression of mitotic activity.
- Taxon
- Tradescantia edwardsiana
Tradescantia edwardsianae2 - Treatment
- cold treatmente0
- Outcome
- DNAe2
- Direction
- increasee2
- Value
- slighte2
- Qualifier
- attributed to the suppression of mitotic activitye2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Three plant species and one animal species have been subjected to cold treatment”
e2“Tradescantia edwardsiana, which has supernumerary chromosomes, shows a slight increase in DNA which is attributed to the suppression of mitotic activity”
Claim · model-written summary
The decrease of DNA after cold treatment appears to be due to a deficiency of the labile DNA fraction.
- Taxon
- Trillium erectum and Trillium sessileTrillium sessileTrillium erectume3
- Outcome
- decrease of DNAe4
- Qualifier
- deficiency of this labile fraction of DNAe4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“There are at least two types of DNA present in Trillium erectum and Trillium sessile, a stable type associated with gene-bearing regions and a more labile type found in heterochromatic regions”
e4“The decrease of DNA caused by cold treatment appears to be due to a deficiency of this labile fraction of DNA”
Claim · model-written summary
Trillium erectum and Trillium sessile have at least two types of DNA: a stable type with gene-bearing regions and a more labile type in heterochromatic regions.
- Taxon
- Trillium erectum and Trillium sessileTrillium sessileTrillium erectume3
- Outcome
- types of DNAe3
- Qualifier
- a stable type associated with gene-bearing regions and a more labile type found in heterochromatic regionse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“There are at least two types of DNA present in Trillium erectum and Trillium sessile, a stable type associated with gene-bearing regions and a more labile type found in heterochromatic regions”
Claim · model-written summary
Changes in DNA quantity after cold treatment occur only in selected plants with large heterochromatic regions.
Verbatim
e6“The changes in quantity of DNA due to cold treatment occur only in selected plants having large heterochromatic regions”