Germ-line cells

Information metabolism provides a way to store and retrieve the information that guides the development of cellular structure, communication, and regulation. Like other metabolic pathways, this process is highly regulated. Information is stored by the process of DNA replication and meiosis, in which we form our germ-line cells. These processes are limited to specific portions of the cell cycle. Information is retrieved by the transcription of DNA into RNA and the ultimate translation of the signals in the mRNA into protein. 

In two dominant lethal studies, neither heptachlor nor heptachlor epoxide proved to be clastogenic in the germ-line cells of male Charles River or Swiss mice (Arnold et al. 1977 Epstein et al. 1972). 

There are very few in vivo genotoxicity studies. Only two in vivo studies were located, and both assessed the dominant lethal effects. The results were negative for both studies, implying that neither heptachlor nor heptachlor epoxide are genotoxic to the germ-line cells of male mice when tested alone or as a mixture (Arnold et al. 1977 Epstein et al. 1972). Refer to Table 2- 3 for a summary of these results of in vivo studies. 

In germ-line cells and other cell types that do not undergo aging, telomere lengths are maintained by telomerases. 

One of the best known eukaryotic transposons is the P element of Drosophila, which transposes only within the germ line cells of developing embryos, somatic cells being unaffected.265 625 626 It belongs to... 

No complete antibody gene exists in germ-line cells. The genes for light chains and heavy chains assemble by somatic recombination during B-lymphocyte maturation. 

Somatic In most animals, it is possible to distinguish germ-line cells from somatic cells,... 

Mutations in tumor suppressor genes (many of which code for transcription factors) alter an essential cellular activity that regulates growth. Mutations occur both in somatic cells and in germ line cell and are often the cause of hereditary cancers. 

In sexually reproducing animals like ourselves, mutations can be Inherited only If they are present In cells that potentially contribute to the formation of offspring. Such germ-line cells Include eggs, sperm, and their precursor cells. Body cells that do not contribute to offspring are called somatic cells. Mutations that occur In these cells never are Inherited, although they may contribute to the onset of cancer. Plants have a less distinct division between somatic and germ-line cells, since many plant cells can function In both capacities. 

Germ-line cells give rise to eggs or sperm. By definition, all other cells are somatic cells. 

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