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Increases in the number and size of enclaves of the new immigrant groups from Latin America and Asia during the 1980s have changed the ethnic composition of many American cities. I have classified primary and secondary enclave networks for each immigrant country of origin in order to examine changes in the geographic concentration of immigrants. First I calculated the Duncan index of dissimilarity for immigrants relative to natives at the metropolitan area level. I then use individual-level data to follow immigrant cohorts over time in order to examine how time in the United States is associated with movements from primary enclaves to other geographic areas in the immigrant networks. There is movement from the primary enclave to the periphery of the primary enclave, to areas of smaller groupings of immigrants from the same country of origin, and to areas that do not have large groupings of immigrants from the same country. It is significant that many of these changes in location occur quite late in the assimilation process.

Caimey, J. 1996, Gene expression under water deficit in loblolly pine (Pinus taeda): Isolation and characterization of cDNA clones, -Physioi. Plant. 97: 139-148,Poly(A*) RNA was extracted from roots of loblolly pine (Pinus taeda L.) seedlings subjected to gradual and prolonged water deficit. This RNA was used to constmct a cDNA library, A number of cDNA clones were isolated whose expression was induced by water deficit. Four of these cDNA clones, designated pLP2, pLP3, pLP4 and pLP5, were characterized further. Each of these pine genes has unique characteristics either in sequence or pattem of expression. The protein encoded by pLP2 shows 91% identity to S-adenosylmethionine synthetase from a range of plants. The protein encoded by pLP3 is similar to a tomato protein induced by water deficit and during fruit ripening, but the pine protein possesses a unique 34-amino-acid region near the aniino terminal. The LP4 protein is similar to stellacyanin, a copper-binding protein in the Japanese lacquer tree, but possesses a proline/serine-rich caiboxy terminus not found in other plants. Clone pLP5 encodes a novel glycine-rich protein with similarity to both silk fibroin and the rat chondroitin core protein, but the putative pine protein is distinct from previously characterized glycine-rich proteins. Transcript levels of the four genes rose under moderate water deficit stress and then declined as stress became severe (1 month without water), with the exception of pLP5 mRNA, which remained at elevated levels even under severe stress. The possible roles of the encoded proteins in cell wall reinforcement are discussed.