Symbiotic nitrogen fixation (SNF) by intracellular rhizobia within legume root nodules requires the exchange of nutrients between host plant cells and their resident bacteria. Little is known at the molecular level about plant transporters that mediate such exchanges. Several mutants of the model legume Lotus japonicus have been identified that develop nodules with metabolic defects that cannot fix nitrogen efficiently and exhibit retarded growth under symbiotic conditions. Mapbased cloning of defective genes in two such mutants, sst1-1 and sst1-2 (for symbiotic sulfate transporter), revealed two alleles of the same gene. The gene is expressed in a nodule-specific manner and encodes a protein homologous with eukaryotic sulfate transporters. Full-length cDNA of the gene complemented a yeast mutant defective in sulfate transport. Hence, the gene was named Sst1. The sst1-1 and sst1-2 mutants exhibited normal growth and development under nonsymbiotic growth conditions, a result consistent with the nodule-specific expression of Sst1. Data from a previous proteomic study indicate that SST1 is located on the symbiosome membrane in Lotus nodules. Together, these results suggest that SST1 transports sulfate from the plant cell cytoplasm to the intracellular rhizobia, where the nutrient is essential for protein and cofactor synthesis, including nitrogenase biosynthesis. This work shows the importance of plant sulfate transport in SNF and the specialization of a eukaryotic transporter gene for this purpose.

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Previous research suggests that girls have higher occupational aspirations than boys before entering the labor market. We investigate whether this gender gap in occupational aspirations generalizes to secondary school students in Germany and illuminate the possible mechanisms behind these purported gender differences. For this purpose, we used a large and representative sample of ninth graders ( N = 10,743) from the German National Educational Panel Study. Adolescents’ occupational aspirations were coded on the International Socio-Economic Index of Occupational Status (ISEI) according to the socioeconomic status of the aspired occupation. Results showed that girls’ occupational aspirations were 6.5 ISEI points higher than boys’ (Cohen’s d = .36). Mediation analyses further revealed that gender differences in vocational interest could explain one-half of the gender gap in occupational aspirations. This suggests that girls’ higher occupational aspirations reflect their specific vocational interests rather than a general striving for higher status and prestige compared to boys.

The present study compares native and immigrant students regarding the direction and the strength of the relation between intrinsic reading motivation and reading competence. Within the framework of the German National Educational Panel Study, 4,619 secondary school students were included in the analyses. The present study confirmed the reciprocal cross-lagged effects between intrinsic reading motivation and reading competence from grades 5 to 7 for native students. In addition, the effect of grade 5 intrinsic reading motivation on grade 7 reading competence was mediated by grade 6 reading amount. However, for immigrant students, although the crosslagged effect of grade 5 reading competence on grade 7 intrinsic reading motivation was significant, the reverse effect was not significant. The present findings suggest that intrinsic reading motivation seems to be essential for the development of reading achievement for native students whereas it seems to be of less importance for immigrant students. HighlightsWhat is already known about this topic?• Intrinsic reading motivation and reading competence are significantly and positively correlated with each other.• The relation between intrinsic reading motivation and reading competence is mediated by reading amount.