The World Bank A considerable amount of research has been conducted on the topic of migration and remittances over the last few years. Early studies on immigration policy assumed that migrants leave their countries, settle in a new country, start integrating in their new society, and abandon their ties with their country of origin. Today, however, globalization makes it possible for immigrants to remain connected with their native countries while residing abroad. To address the latest developments on migration and remittances, the authors provide a global survey of the analytical and empirical literature on these issues. This paper reviews evidence on how migrants contribute to the economic development of their countries of origin. In addition to describing the state of knowledge regarding flows of people and migrant remittances worldwide, it focuses on the current literature dealing with the development impact of transfers of money, knowledge, and skills by migrants back to their home countries. The paper also examines the complex question of the impact of highly skilled migration on labor sending countries. There is a continuing debate over what role migration should play in the mix of policies available in order to promote economic development. Although mechanisms for liberalizing goods, services and capital markets are in place, the international mobility of labor still faces stringent restrictions. The paper, therefore, reviews proposed mechanisms to strengthen the governance of international migration, including policy options to make migration management bilateral, regional, or

Previously, the immunophilin-like protein TWD1 from Arabidopsis has been demonstrated to interact with the ABC transporters AtPGP1 and its closest homologue, AtPGP19. Physiological and biochemical investigation of pgp1/pgp19 and of twd1 plants suggested a regulatory role of TWD1 on AtPGP1/AtPGP19 transport activities. To further understand the dramatic pleiotropic phenotype that is caused by loss-of-function mutation of the TWD1 gene, we were interested in other TWD1 interacting proteins. AtMRP1, a multidrug resistance-associated (MRP/ABCC)-like ABC transporter, has been isolated in a yeast two-hybrid screen. We demonstrate molecular interaction between TWD1 and ABC transporters AtMRP1 and its closest homologue, AtMRP2. Unlike AtPGP1, AtMRP1 binds to the C-terminal tetratricopeptide repeat domain of TWD1, which is well known to mediate protein-protein interactions. Domain mapping proved that TWD1 binds to a motif of AtMRP1 that resembles calmodulin-binding motifs; and calmodulin binding to the C-terminus of MRP1 was verified. By membrane fractionation and GFP-tagging, we localized AtMRP1 to the central vacuolar membrane and the TWD1-AtMRP1 complex was verified in vivo by coimmunoprecipitation. We were able to demonstrate that TWD1 binds to isolated vacuoles and has a significant impact on the uptake of metolachlor-GS and estradiol-␤-glucuronide, well-known substrates of vacuolar transporters AtMRP1 and AtMRP2.

SummaryATP-binding cassette (ABC) transporters are membrane proteins responsible for cellular detoxi®cation processes in plants and animals. Recent evidence shows that this class of transporters may also be involved in many other cellular processes. Because of their homology with human multidrug resistance-associated proteins (MRP), cystic ®brosis transmembrane conductance regulator (CFTR) and sulfonylurea receptor (SUR), some plant ABC transporters have been implicated in the regulation of ion channel activities. This paper describes an investigation of the AtMRP4 gene and its role in stomatal regulation. Reporter gene studies showed that AtMRP4 is highly expressed in stomata and that the protein is localized to the plasma membrane. Stomatal aperture in three independent atmrp4 mutant alleles was larger than in wild-type plants, both in the light and in the dark, resulting in increased water loss but no change in the photosynthetic rate. In baker's yeast, AtMRP4 shows ATP-dependent, vanadate-sensitive transport of methotrexate (MTX), an antifolate and a substrate of mammalian MRPs. Treatment with MTX reduced stomatal opening in wild-type plants, but had no effect in atmrp4 mutants. These results indicate the involvement of AtMRP4 in the complex regulation of stomatal aperture.

Previous cross-cultural research into social support has attributed national variations in observed support to assumed cultural variables, but has rarely measured these variables directly. Furthermore, this cross-cultural work has failed to differentiate between support from friends and from families, and between global perceptions of available support and the support received after an event. In this study, 140 respondents from UK (N = 72) and Spain (N = 68) completed scales assessing cultural collectivism (Bierbrauer, Meyer, & Wolfradt, 1994), measures of perceived global support (Cohen & Hoberman, 1983), and received social support, as well as additional indices of self-esteem (Rosenberg, 1965) and life satisfaction (Diener, Emmons, Larsen, & Griffin, 1985). Path analytic analyses found that Spanish respondents were, as expected, more collectivist than their British counterparts, and that collectivism predicted reported family support after an event and global perceptions of available support. Global perceived support and support from friends after an event were significant correlates of self- esteem, which, along with global support and support from family members, was a significant correlate of life satisfaction. These findings underline the importance of analysing cultural values and the multiple components of social support when assessing the impact of culture on support.

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Zinc (Zn) hyperaccumulation is a constitutive property of Thlaspi caerulescens, whereas cadmium (Cd) hyperaccumulation varies greatly among different ecotypes. The molecular basis of this variation is unknown. Ecotypic differences in the sequences and expression of four representative ZIP family transporter genes were investigated. Genome analysis indicated the presence of at least two closely related copies of the TcIRT1 gene in both Ganges (high Cd accumulating) and Prayon (low Cd accumulating) ecotypes, with different copies being expressed in each, and, furthermore, the two genes potentially encode different length transcripts. The predominant transcript in Prayon was truncated, missing sequence coding for the putative metal-binding site and the five C-terminal transmembrane helices. The two ecotypes were grown hydroponically +/-Fe and Cd, and mRNA abundance determined for four ZIP genes. The four ZIP genes studied (TcIRT1, TcIRT2, TcZNT1, and TcZNT5) were expressed in roots only. TcIRT1 expression (full-length in Ganges, TcIRT1-1G; truncated in Prayon, TcIRT1-2P) was enhanced by Fe deficiency or by exposure to Cd. TcIRT2 expression was induced by Fe deficiency, but was unaffected by Cd exposure. TcZNT5-G showed greater expression in Prayon compared with Ganges. The functions of TcIRT1 from Ganges and Prayon and the Arabidopsis homologue were analysed by heterologous expression in yeast. All three IRT1 genes were able to facilitate growth on low Fe concentrations. Cd sensitivity of yeast was conferred in the order AtIRT1>TcIRT1-1G>TcIRT1-2P (truncated). Cd uptake after 4 h was only detectable following complementation by AtIRT1. The results suggest that although TcIRT1-G may be involved in Cd hyperaccumulation in the Ganges ecotype of T. caerulescens, the transporter expressed in yeast does not have an enhanced ability to transport Cd compared with AtIRT1. Therefore, the unique Cd-accumulating ability of the T. caerulescens Ganges ecotype must be due to the levels of expression of the protein or to other factors such as interacting proteins.

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