Questions of emigration, circulation and return: mobility between the French Caribbean and France.

"The last four decades have seen the establishment of close migratory links between the French Caribbean islands of Martinique and Guadeloupe and the metropole.... The present paper focuses on the...complex migratory links--including continuing emigration from the islands for work and education, return migration and circulation--which have come to characterise the 1980s.... The paper aims also to contribute to the broader conceptualisation of migration and mobility. The principal conclusions reveal that the more straightforward labour migration of the years from 1963 to 1981 has been replaced by some considerable return migration (amongst young adults particularly) and circulation.... The paper also demonstrates that the role of migration in reducing population growth and fertility in the islands has been much altered during the course of the 1980s."

Kinetic analysis of the non-phosphorylated, in vitro phosphorylated, and phosphorylation-site-mutant (Asp8) forms of intact recombinant C4 phosphoenolpyruvate carboxylase from sorghum.

Steady-state kinetic analyses were performed on the non-phosphorylated, in vitro phosphorylated and phosphorylation-site mutant (Ser8-->Asp) forms of purified recombinant sorghum C4 phosphoenolpyruvate (P-pyruvate) carboxylase (EC 4.1.1.31) containing an intact N-terminus. Significant differences in certain kinetic parameters were observed between these three enzyme forms when activity was assayed at a suboptimal but near-physiological pH (7.3), but not at optimal pH (8.0). Most notably, at pH 7.3 the apparent Ki for the negative allosteric effector L-malate was 0.17 mM, 1.2 mM and 0.45 mM while the apparent Ka for the positive allosteric effector glucose 6-phosphate (Glc6P) at 1 mM P-pyruvate was 1.3 mM, 0.28 mM and 0.45 mM for the dephosphorylated, phosphorylated and mutant forms of the enzyme, respectively. These and related kinetic analyses at pH 7.3 show that phosphorylation of C4 P-pyruvate carboxylase near its N-terminus has a relatively minor effect on V and Km (total P-pyruvate) but has a dramatic effect on the extent of activation by Glc6P, type of inhibition by L-malate and, most especially, Ka (Glc6P) and Ki (L-malate). Thus, regulatory phosphorylation profoundly influences the interactive allosteric properties of this cytosolic C4-photosynthesis enzyme.

An engineered change in the L-malate sensitivity of a site-directed mutant of sorghum phosphoenolpyruvate carboxylase: the effect of sequential mutagenesis and S-carboxymethylation at position 8.

A recombinant, site-directed mutant form of sorghum phosphoenolpyruvate carboxylase (PEPC), in which the phosphorylatable serine residue (Ser-8) was changed to cysteine (S8C), was chemically modified by iodoacetic acid and iodoacetamide for the purpose of testing the effect of introducing a negative charge at position 8. S-Carboxymethylation of the Cys-8 enzyme by iodoacetic acid decreased its sensitivity to L-malate from an I0.5 (50% inhibition) value of 0.12 to 0.35 mM at pH 7.3 when the active-site domain was protected during modification by the substrate phosphoenolpyruvate (PEP). In contrast, neither S-carboxymethylation of the wild-type enzyme nor modification of the mutant enzyme by iodoacetamide caused any change in the enzyme's sensitivity to L-malate. The modified, substrate-protected forms of the Ser-8 and S8C PEPCs had Km(total PEP) and Vmax values virtually identical to those of the unmodified control enzymes. Similar specific increases in the I0.5 value of L-malate have been reported previously for in vitro phosphorylated leaf and recombinant Ser-8 PEPCs, the site-directed mutant Asp-8 enzyme, and C4-leaf PEPC purified from light-adapted sorghum or maize (in vivo phospho-form). Therefore, these data from different but complementary experimental approaches provide convincing evidence that the effect of phosphorylation of Ser-8 on the L-malate sensitivity of sorghum C4-PEPC is caused by the introduction of negative charge into this N-terminal regulatory domain.

The development of self-administered physical activity surveys for 4th grade students.

This study evaluates the test-retest reliability and validity of self-report measures of physical activity that can be self-administered in classroom settings to 4th grade students. Four different self-report formats were tested on 66 students. To assess test-retest reliabilities, self-report measures were administered on two occasions, separated by a 3-day interval between Time 1 (Friday) and Time 2 (Monday). One-way model intraclass reliabilities ranged from .51 to .74. Three days of monitoring with the Caltrac accelerometer were used as the validity criterion. Only one of the three weekly recalls, the Weekly Activity Checklist, was supported by significant validity correlations at both Time 1 (r = .34, p < .01) and Time 2 (r = .26, p < .05). The 1-day recall, Yesterday Activity Checklist, correlated significantly (r = .33, p < .01) with the previous day's Caltrac monitor score. Although two of the physical activity recall formats were found to be superior to two others, these data highlight the limitations of children's self-reports. Two self-report formats were found to have modest levels of reliability and validity with 4th grade children when administered in a classroom setting.

Site-directed mutagenesis of the phosphorylatable serine (Ser8) in C4 phosphoenolpyruvate carboxylase from sorghum. The effect of negative charge at position 8.

The properties of the dephospho and in vitro phosphorylated forms of recombinant sorghum phosphoenolpyruvate carboxylase have been compared with those of the authentic dark (dephospho) and light (phospho) leaf enzyme forms and two mutant enzymes in which the phosphorylatable serine residue (Ser8) has been changed by site-directed mutagenesis to Cys (S8C) or Asp (S8D). Kinetic analysis of the purified recombinant, mutant, and leaf enzyme forms at pH 8.0 indicated virtually identical Vmax, apparent Km (phosphoenolpyruvate), and half-maximal activation (glucose 6-P) values of about 44 units/mg, 1.1 mM, and 0.23 mM, respectively. In contrast, the Ser8, S8C, and dark leaf enzymes were about 3-fold more sensitive to inhibition by L-malate at pH 7.3 than the Ser8-P, S8D, and light leaf enzyme forms. These comparative results indicate that: (i) Ser8 is an important determinant in the regulation of sorghum phosphoenolpyruvate carboxylase activity by negative (L-malate), but not positive (glucose 6-phosphate) metabolite effectors, (ii) phosphorylation of this target residue can be functionally mimicked by Asp, but not Cys, and (iii) negative charge contributes to the effect of regulatory phosphorylation on this C4-photosynthesis enzyme.

Afro-Caribbean migrants in France: employment, state policy and the migration process.

"Afro-Caribbean labour in France plays a distinctive role relative to the French population as a whole and the foreign immigrant population. Using a variety of qualitative and quantitative sources, this paper demonstrates that the role of the state in the process of migration from the French Caribbean islands of Martinique and Guadeloupe from the early 1960s onwards was crucial.... Aggregate sources are used to describe detailed occupational distributions while records of individual migrants illustrate the process of migration and the influences on employment. At a time usually characterized by lack of direct involvement in migration by the French state, for Afro-Caribbeans state intervention in recruitment, training and settlement is shown to be very substantial."