Somatization, differential

Reubinoff, B.E., Pera, M.F., Fong, C.Y., Trounson, A., Bongso, A. (2000). Embryonic stem cell lines from human blastocysts somatic differentiation in vitro. Nat Biotechnol, 18, 399-404. Erratum in (2000) Nat Biotechnol. 18, 559. 

As I pointed out in chapter 3, one of the ways to regulate gene expression is to switch off genes by DNA methylation or switch them on by demethylation. DNA methylation patterns in ordinary (somatic) differentiated cells are usually stable, their methylation patterns are passed on to daughter cells when they divide. 

Right oral dikinetid consists of a single segment. Right oral dikinetid consists of 2 segments with only the posterior s segment somatically differentiated. 

Cellular therapies in transplantation and cancer are based on specific cells separated or sorted from human blood, bone marrow, or cord blood by means of their specific cell surface markers or cell differentiation antigens, e.g., CD3, CD4, CD8, CD 14, CD 19, and CD34. For example, the CD34+ stem cells, especially those derived from human embryos, have the capacity to differentiate in culture to generate different somatic cells, e.g., liver cells, heart cells, neurons, etc. This exploding field of research is now termed regenerative medicine. 

Somatic hypermutation High frequency of mutation that occurs in the gene segments encoding the variable regions of antibodies during the differentiation of B lymphocytes into antibody-producing plasma cells. 

Myopathies have been described in several sporadic cases with lactic acidosis, cytochrome oxidase (COX)-positive RRF in muscle, and isolated complex I deficiency, and have been attributed to various pathogenic mutations in ND genes. The sporadic nature of these myopathies suggests that the ND mutations are de novo, arising spontaneously in myogenic stem cells after germ-layer differentiation (somatic mutations) [14]. 

Yamaguchi M, Kondo I. Immunoelectron microscopy of Proteus vulgaris by the plasma polymerization metal-extraction replica method differential staining of flagellar (H) and somatic (0) antigens by colloidal golds. J Electron Microsc 1989 38 382-388. 

Figure 3. Representative linker histone variants from human (Homo sapiens H.s.), and yeast (Saccha-romyces cerevisiae S.c.). The globular domain indicates the winged helix DNA binding domain that is common for all linker histones. Hlc is a typical somatic linker histone common for most cells. H° is expressed in all somatic cells, but is more abundant in terminally differentiated tissues. Hlfoo is an oocyte-specific linker histone. The structure of S. cerevisiae Hholp with two globular domains is a notable deviation...

In Xenopus, in addition to the role in 5S RNA gene regulation, somatic HI has been shown to be involved in further stages of differentiation. The restriction of myoD expression, a marker for the loss of the ability by ectodermal cells to differentiate into mesoderm, requires the presence of somatic histone HI [144]. Again, the globular domain alone and not the whole HI molecule is required to confer this effect [142]. 

Kim, Y.-J., Hwang, I., Tres, L.L., Kierszenbaum, A.L., and Chae, C.-B. (1987) Molecular cloning and differential expression of somatic and testis-specific H2A histone genes during rat spermatogenesis. Dev. Biol. 124, 23-34. 

Somatic mutation. During differentiation of B cells into plasma cells, the coding genes mutate. In this way, the primordial germline genes can become different somatic genes in the individual B cell clones. 

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