Interphase mapping

Some Fundamental Aspects of Interphase Mapping by Indentation Techniques... 

The very beginning of the first mitotic cell cycle of the mouse embryo seems to be controlled by the mechanisms characteristic for both meiotic and mitotic cell cycles. Active MAP kinase, its substrate p90rsk and the CSF activity itself could influence the cellular processes within the one-cell embryo. Indeed, we have observed that despite the entry into the interphase (as judged by the low activity of MPF) some proteins are actively phosphorylated as during the meiotic M phase (e.g. 35 kDa complex Howlett et al 1986, Szollosi et al 1993), the nuclei and the microtubule interphase network start to form only 1.5 hours after activation (Szollosi et al 1993). This delay in the phenomena characteristic for the interphase could be linked to the mixed meiotic/mitotic character of this early period. This delay probably allows the correct transformation of the sperm nucleus into the male pronucleus. In species like Xenopus or Drosophila the transitional period between the meiotic and the mitotic cell cycle control is probably much shorter since it is proportional to duration of the short first cell cycle of these rapidly cleaving embryos. Mammalian embryos are perhaps the most suitable to study this transition because of the exceptionally long first embryonic cell cycle. 

In yeast, the MAP kinase Fus3 induces cell cycle arrest via the degradation of cyclins, Clnl and Cln2. The mitotic cyclins (CYCLIN) are cell cycle proteins that bind the protein kinase Cdc2 during interphase... 

Molecular cytogeneticists in detecting chromosome aberrations in interphase cells (Interphase Cytogenetics, especially Cancer Genetics, 9-11), sex determination (12,13), and gene mapping by nonisotopic in situ hybridization (NISH, 14,15). 

In interphase, microtubules are stabilized by several kinds of proteins that are found all along microtubules and are called MAPs. They tend to have repeating domains, which allow each MAP molecule to associate with more than one tubulin dimer. This produces a doubly effective method of controlling assembly, in that the conformations of several tubulin dimers may be individually stabilized and the stabilized subunits are also cross-linked. The binding of these structural MAPs is in turn controlled by kinases and phosphatases (Cassimeris and Spittle, 2001). During mitosis they are phosphorylated and detach from tubulin, whose assembly and disassembly comes under the control of proteins that operate more at the ends of microtubules. Differentiated cells, such as neurons, do not divide. However, as microtubules and MAPs are slowly transported along axons (Baas and Buster, 2004), the MAPs maybe phosphorylated in particular places, at times when structural plasticity is required for making synapses or other contacts. 

PI clones Genomic sequences 90 kb Genes Mapping Interphase cytogenetics Usually make good FISH probes High... 

Lambda Genomic sequences 12 kb Mapping Interphase cytogenetics Better to use PI or cosmid clones Medium... 

Figure 2.4 shows a comparison of the results obtained from the PCA and real chemical models for a Raman emulsion image [30]. The latter image is formed by four constituents related to the drop phase, the interphase, an additive and the off-drop phase. The two models (real and PCA) resemble each other when considering general trends for example, the score maps are reminiscent of the real distribution maps, although the information seems to be more mixed, and the most salient spectral features in the real spectra can also be found in the different... 

For mapping, BrdU is added to enhance chromosome elongation and banding for metaphase chromosomes and to help distinguish G1 from S and G2 phase nuclei in the case of interphase chromosomes. Treatment of the cells for a few minutes with hypotonic solutions to make them swell and exposure to low temperatures, thus interfering with the stability of spindle fibres, can improve the preparations. 

In situ hybridization experiments with several different fluorescent-labeled probes to DNA in human Interphase cells support the loop model shown in Figure 10-24. In these experiments, some probe sequences separated by millions of base pairs in linear DNA appeared reproducibly very close to one another in interphase nuclei from different cells (Figure 10-25). These closely spaced probe sites are postulated to lie close to specific sequences in the DNA, called scaffold-associated regions (SARs) or matrix-attachment regions (MARs), that are bound to the chromosome scaffold. SARs have been mapped by digesting histone-depleted chromosomes with restriction enzymes and then recovering the fragments that are bound to scaffold proteins. 

The density profile across the interface follows an exponential decay (see Figure 1.1). The intercepts of the steepest tangential line with the horizontal lines defining the volume fraction of either one of the two polymeric ingredients, (p = 0 and 1, define the thickness of the interphase, Al [Helfand and Tagami, 1971, 1972]. Experimentally Al varies from 2 to 60 run [Kressler et al., 1993 Yukioka and Inoue, 1993, 1994]. Measurements of Al have been recently used to map the miscibility region of PC/SAN blends when varying the AN-content and temperamre [Li et al, 1999]. 

Fig. 7.4 Micro-FTIR map of the interphase for DGEBA-lPDA (left) and DGEBA-DETA systems (right).

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