Book ChapterDOI
B-Chromosome Systems in Flowering Plants and Animal Species
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This chapter discusses the B-chromosome systems in flowering plants and animal species, which are completely stable during the cell cycle and are inherited in a constant and unchanging form along with the A chromosomes.Abstract:
Publisher Summary This chapter discusses the B-chromosome systems in flowering plants and animal species. The term B chromosome is introduced to describe extra chromosome which have little if any effect on visible characters of the plant, which are not homologous with the A chromosomes of the normal complement, and which are extremely irregular in their meiotic distribution. B Chromosomes are now known under a variety of different names, including supernumerary and accessory, which are the most common alternatives. B chromosomes are dispensable and nonhomologous with A chromosomes. These two characteristics above all others most sharply differentiate them from members of the basic A-chromosome complement. The distribution of B chromosome in plant and animal species is discussed. In many plants and animals the B chromosomes are completely stable during the cell cycle and are inherited in a constant and unchanging form along with the A chromosomes. Some plant species have an apparent order in their instability, which results in exclusion and/or accumulation of B chromosomes in specific tissues and organs. The significance of B-chromosome effects in flowering plants and animals is discussed.read more
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Journal ArticleDOI
Nuclear volume control by nucleoskeletal DNA, selection for cell volume and cell growth rate, and the solution of the DNA C-value paradox.
TL;DR: Eukaryote DNA can be divided into genic DNA, which codes for proteins (or serves as recognition sites for proteins involved in transcription, replication and recombination), and nucleoskeletal DNA (S-DNA), which exists only because of its nucleoskeleton role in determining the nuclear volume.
Journal ArticleDOI
Chromosome banding in Amphibia
TL;DR: A cytogenetic study performed on a population of the South American leptodactylid frog Eleutherodactylus maussi revealed multiple sex chromosomes of the X1X1X2X2♀/X1 X2Y♂ (=XXAA/XXAY♂) type, which is interpreted as the ancestral condition, preceding the occurrence of the Y-autosome fusion.
Journal ArticleDOI
Forty four probands with an additional “marker” chromosome
TL;DR: Information is presented which has been obtained from an exhaustive examination of 44 probands with a supernumerary marker chromosome (mar) and their families and the practical problems in assessing the risk of abnormality in a foetus discovered during prenatal diagnosis to be carrying a mar.
Journal ArticleDOI
B chromosomes in plants
TL;DR: This review of supernumerary B chromosome systems in flowering plants deals mainly with work published in the last 15 yr, but also includes older material which has not hitherto been presented systematically.
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Journal ArticleDOI
Mechanism of Immunologically Specific Killing of Tumour Cells by Macrophages
R. Evans,P. Alexander +1 more
TL;DR: The experiments to be described show that the killing of tumour cells by macrophages is made up of an immunologically specific interaction which is followed by a non-specific lethal reaction.
Journal ArticleDOI
The association of non-homologous parts of chromosomes in the mid-prophase of meiosis in Zea mays
TL;DR: In many cases, the non-homologous association at pachytene appears to be as intimate as homologueous association, andTranslocations probably result from the association of non-Homologous parts of chromosomes.
Journal ArticleDOI
Chromosome behaviour and structural hybridity in the tradescantiae. II.
TL;DR: Fragments are small in Rhoeo and in the tetraploids, showing that the assumption of pairing and crossing-over being restricted to the end regions is justified and that the anaphase in some forms comes to correspond with the hollow metaphase in others.