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The article discusses the entry of European Economic Community (E.E.C.) in Great Britain and its subsequent effect on the growth of economy. Relative to other European countries and Japan, Britain's slower rate of growth during the last two decades was associated with a lower level of investment, a slower rate of growth of exports and a slower rate of growth of labor productivity. The relation between investment and exports is indirect. This arises because of the possibility of direct foreign manufacturing investment as an alternative to exporting when it comes to supplying foreign markets. The mechanisms by which membership of the E.E.C. can affect Britain's growth in exports, investment and productivity is classified under three headings according to the differences that entry will make compared to non-entry. The entry will effect the various adjustments in tariffs, the required removal of Great Britain control on direct investment outflow to other E.E.C. countries, and the "confidence" factor. With export sales, profit margin is likely to be lower or negative because of tariffs and higher distribution and marketing costs.

Previous studies have shown that there is a deoxyribonucleic acid (DNA) segment, of length 1.3 kb and denoted as the alphabeta sequence, which occurs twice on the F plasmid at corrdinates 93.2 to 94.5/OF kb and 13.7 to 15.0F kb. In the present investigation, heteroduplexes were prepared between a phage DNA carrying the insertion sequence IS3 and suitable F-prime DNAs. The hybrids formed show that IS3 is the same as alphabeta. This result plus previous studies support the view that: (i) the insertion sequence IS2 and IS3 occur on F and, in multiple copies, on the main bacterial chromosome of Escherichia coli K-12; and (ii)these IS sequences on the main bacterial chromosomes are hot spots for Hfr formation by reciprocal recombination with the corresponding sequences of F.

The structure of F13, a plasmid containing lac, purE, and proC, has been determined by heteroduplex analysis. As expected for an F-prime formed by a type II excision event, it contains all the sequences of F plus a large segment of Escherichia coli chromosomal deoxyribonucleic acid. There is a sequence of F with coordinates 16.3-17.6F which has been shown in other studies to be the insertion sequence IS2. This IS2 occurs twice on F13, once at each of the two junctions of F deoxyribonucleic acid with chromosomal deoxyribonucleic acid. The sequence alpha beta which occurs twice on F with coordinates 93.2-94.5/OF and 13.7-15.0F occurs an additional three times, twice in an inverted order relative to the alpha beta sequences of F, on the chromosomal sequences of F13. The structures of the plasmids F13-4 and F210 have been determined. The common sequences of F13 with F152-1 (a derivative of F152, the classical F2gal) and with F13-4 and F210 have been mapped. These results partially map lac, proC, tsx, and purE on F13. On the basis of all of these results, it is proposed that Hfr 13 (the parent of F13) was formed by recirpocal recombination between IS2 on F and an IS2 resident at a point between lac and proC on the chromosome of the F+ parent of Hfr 13. It is proposed that this IS2 and the several alpha beta sequences on the chromosomal part of F13 are hot spots for recombination with F, i.e., for Hfr formation. The point of origin and direction of transfer of many Hfr's can be explained by this hypothesis. In particular, the sequence relations of F42-1 (Flac) and of F152-1 (F 2gal) with F13 are completely consistent with this model.

Heteroduplex experiments between the plasmid R6 and one strand of the deoxyribonucleic acid (DNA) of a lambda phage carrying the insertion sequence IS1 show that IS1 occurs on R6 at the two previously mapped junctions of resistance transfer factor (RTF) DNA with R-determinant DNA. From previous heteroduplex experiments, it then follows that IS1 occurs at the same junctions in R6-5, R100-1, and R1 plasmids. Heteroduplex experiments with the DNA from a lambda phage carrying the insertion sequence IS2 show that one copy of IS2 occurs in R6, R6-5, and R100-1 (but not R1) at a point within the RTF with coordinates 67.5 TO 68.9 kilobase units (kb). In an accompanying paper, Ptashne and Cohen (1975) show that the insertion sequence IS3 occurs on R6 and R6-5. R100-25, a traC mutant, differs from its parent R100-1 only in that it contains an additional copy of IS1 inserted within the tra gene region of 82.1 kb. R100-31, atraX, TC-s mutant of R100-1, is deleted in R100-1 sequences starting at one of the IS3 termini (46.9 kb) and extending with RTF to 61.0 kb. Heteroduplex studies of F plasmids with the DNA of a lambda phage bearing insertion sequence IS2 show that the sequence of F with coordinates 16.3-17.6F is IS2. The occurrence of IS1 at the two junctions of R-determinant DNA and RTF DNA in R plasmids provides a structural basis to explain the mechanism of the previously observed formation of molecules containing one RTF unit and several tandem copies of the R-determinant unit, when R plasmids in Proteus mirabilis are grown in the presence of antibiotics, and the segregation of an R plasmid into an RTF unit and an R-determinant unit. In general, correlation of our results with previous studies shows that insertion sequences play a role in a variety of F- and R-related intra- and intermolecular recombination phenomena.