Multiple chromosomes

Most dominant lethals probably result from multiple chromosomal breaks in the germ cells. Frequencies are typically much higher in postspermatogonial stages,104 and often there are characteristic patterns of dominant lethality with regard to different stages of sperm development.104 The results can be very useful in determining... 

Cytogenetically MTSCs show multiple chromosomal losses (1, -4, -6, -8, -9, -13, -14, -15, and -22). Differentiation toward loop of Henle, distal convoluted tubule, or collecting ducts has been suggested by their overall immunoprofile and ultrastructural features. 

Briefly, the production of riboflavin with B. subtilis could be increased by the deregulation of purine synthesis and a mutation in the gene coding for the riboflavin kinase. The B. subtilis process is further based on the recombinant, homologous overexpression of multiple chromosomal copies of the riboflavin operon under the control of a strong synthetic promoter. The introduction of an additional copy of the ribA gene has also been shown to increase the productivity of the strain. " ... 

Because eukaryotic cells have multiple chromosomes, it is vital that exactly one copy of the DNAin each be synthesized before the cell divides. This is achieved through a combination of replication licensing, which ensures that DNA synthesis is tightly coupled to passage of cells through the cell cycle, and a series of checkpoints in the cell cycle, at which the integrity of chromosomal DNA is evaluated. 

There are the events that serve as a signal system to specify the time in the cell cycle that DNA synthesis in the nucleus and cytoplasmic organelles commences. The culmination of these events in the late G1 phase is marked by DNA synthetic activity at multiple chromosomal sites indicating the start of S phase. 

Variations of still another kind occur in nature and involve the duplication or loss of entire chromosome sets. From such variations have originated the pol)rploid series of multiple chromosome numbers, which are to be found very generally among related species distributed throughout the plant kingdom. The study of this class of variations has progressed slowly because of their infrequent occurrence under natmal conditions. A technique for the production of new forms with increased or reduced numbers of chromosome sets would make possible the development of new... 

Petersen, K.V., Martinussen, J., Jensen, P.R., and Solem, C. (2013) Repetitive, marker-free, site-spedfic integration as a novel tool for multiple chromosomal integration of DNA. Appl Environ Microbiol 19, 3563-3569. 

Inoue N, Hirata RK, Russell DW. High-fidelity correction of mutations at multiple chromosomal positions by adeno-associated vims vectors. J Virol 1999 73 7376-7380. 

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