Gene Cell division

To circumvent this problem, vectors that are based on lentiviruses have been developed. In contrast to prototypic retroviruses, lentiviruses do not require cell division for integration. Gene-therapy vectors have been developed from a broad spectrum of lentiviruses including human immunodeficiency vims (HIV), simian and feline immunodeficiency vims as well as visna/maedi vims. The most widely used lentiviral vector system is based on HIV-1. These vectors can efficiently transduce a broad spectrum of dividing and nondividing cells including neurons, hepatocytes, muscle cells, and hematopoietic stem cells [1,2]. 

Certain characteristics of skeletal muscle fibers are particularly relevant when considering the future of gene therapy in muscle diseases. Skeletal muscle fibers are large syncytia containing thousands of postmitotic myonuclei, each of which expresses the same set of genes. The postmitotic nature of the myonuclei implies that in mature muscle fibers, cell division cannot play a role in spreading the transferred gene to required locations (i.e., whole muscles). On the other hand, once... 

Integration of the prophage into the bacterial ehromosome ensures that, on cell division, each daughter cell will acquire the set of viral genes. 

Plasmids have the ability to transfer within and between species and can therefore be acquired from other bacteria as well as a consequence of cell division. This property makes plasmid-acquired resistance much more threatening in terms ofthe spread of antibiotic resistance than resistance acquired due to chromosomal mutation. Plasmids also harbour transposons (section 2.1.3), which enhances their ability to transfer antibiotic resistance genes. 

Zachariae W, Nasmyth K 1999 Whose end is destruction cell division and the anaphase-promoting complex. Genes Dev 13 2039-2058... 

Winston N J 1997 Stability of cyclin B protein during meiotic maturation and the first mitotic cell division in mouse oocytes. Biol Cell 89 211-219 Winston NJ, Maro B 1995 Calmodulin-dependent protein kinase II is activated transiently in ethanol-stimulated mouse oocytes. Dev Biol 170 350-352 Winston NJ, Bourgain-Guglielmetti F, Ciemerych MA et al 2000 Early development of mouse embryos null mutant for the cyclin A2 gene occurs in the absence of maternally derived cyclin A2 gene products. Dev Biol 223 139-153... 

Carmena A, Murugasu-Oei B, Menon D, Jimenez F, Chia W1998 Inscuteable and numb mediate asymmetric muscle progenitor cell divisions during Drosophila myogenesis. Genes Dev 12 304-315... 

Tio M, Zavortink M, Yang X, Chia W 1999 A functional analyses of inscuteable and its roles during Drosophila asymmetric cell divisions. J Cell Sci 112 1541—1551 Uemura T, Shepherd S, Ackerman L, Jan LY, Jan YN 1989 numb, a gene required in determination of cell fate during sensory organ formation in Drosophila embryos. Cell 58 349-360... 

Boxem M, Srinivasan DG, van den Heuvel S 1999 The Caenorhabditis elegans gene ncc1 encodes a cdc2-related kinase required for M phase in meiotic and mitotic cell divisions, but not for S phase. Development 126 2227—2239... 

At the organism level, there are three issues that must be tackled, besides that of visual representation the first division, breaking of symmetry, and intercellular communication. The simulation forces the first cell to divide by initializing the node (gene) signifying division to 1. This ensures that the organism divides at least once. 

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