Congenic intervals

Foote I have seen a few presentations where a lot of the interactions have been ds interactions. We see an enormous amount of differential expression between different congenic intervals. 

PCBs in biological samples are usually extracted by a Soxhlet column and with a nonpolar solvent such as hexane. The sample is first mixed with sodium sulfate to remove moisture. The extraction of PCBs from sediments was tested with sonication, with two sonications interspersed at a 24-h quiescent interval, with steam distillation, or with Soxhlet extraction (Dunnivant and Elzerman 1988). Comparison of the recoveries of various PCB mixtures from dry and wet sediments by the four techniques and the extraction efficiency of four solvents showed that the best overall recoveries were obtained by Soxhlet extraction and the two sonication procedures. In comparisons of solvent systems of acetone, acetonitrile, acetone-hexane (1+1), and water-acetone-isooctane (5+1.5+1), recoveries of lower chlorinated congeners (dichloro- to tetrachloro-) were usually higher with acetonitrile and recoveries of higher chlorinated congeners (tetrachloro- to heptachloro-) extracted with acetone were superior (Dunnivant and Elzerman 1988). The completeness of extraction from a sample matrix does not seem to discriminate against specific isomers however, discrimination in the cleanup and fractionation process may occur and must be tested (Duinker et al. 1988b). 

Thus, the concentrations of fatty acids and esters found in brandy distillates are greatly affected by the nature of the wine at the time of distillation, particularly the time interval between fermentation and distillation since most of the yeast cells settle out fairly quickly after fermentation has ceased. Obviously the degree of resuspension of the settled lees into the wine when distilled affects the amount of fatty acids and esters recovered in the distillates. The method and techniques of distillation are also very important since this class of congeners, having relatively high boiling points and weak solubility in water, exhibit wide ranges of volatility as affected by the alcohol content of the liquid volatilized. 

Numerous studies provided doses associated with death following exposure to CDDs in animals. LD50 (lethal dose, kill for 50% of dosed animals during a certain time interval) values for each congener varied not only among species, but also among different strains. 

In summary, the studies by Phillips et al. (1989a) and Taylor and Lawrence (1992) on apparent half-lives of PCB mixtures (Table 3-10) are in general agreement. These are well designed studies in two different occupational cohorts that are not limited by small sample size, short sampling intervals, or low initial body burdens. The main limitation of these studies was that congener specific PCB analysis was not conducted. Nevertheless, these studies provide the best estimates of the apparent half-lives of PCB mixtures following occupational exposure. 

Haywood ME, Rogers NJ, Rose SJ et al 2004 Dissection of BXSB lupus phenotype using mice congenic for chromosome 1 demonstrates that separate intervals direct different aspects of disease. Immunol 173 4277—4285... 

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