A parental report questionnaire posted to a population sample of 18-month-old twins correctly assigned zygosity in 95%of cases when validated against zygosity determined by identity of polymorphic DNA markers. The questionnaire was as accurate when readministered at 3 years of age, with 96% of children being assigned the same zygosity on both occasions. The results validate the use of parental report questionnaire data to determine zygosity in infancy.

The protein kinase GCN2 stimulates expression of the yeast transcriptional activator GCN4 at the translational level by phosphorylating the a subunit of translation initiation factor 2 (eIF-2a) in amino acid-starved cells. Phosphorylation of eIF-2a reduces its activity, allowing ribosomes to bypass short open reading frames present in the GCN4 mRNA leader and initiate translation at the GCN4 start codon. We describe here 17 dominant GCN2 mutations that lead to derepression of GCN4 expression in the absence of amino acid starvation. Seven of these GCN27 alleles map in the protein kinase moiety, and two in this group alter the presumed ATP-binding domain, suggesting that ATP binding is a regulated aspect of GCN2 function. Six GCN2' alleles map in a region related to histidyl-tRNA synthetases, and two in this group alter a sequence motif conserved among class H aminoacyl-tRNA synthetases that directly interacts with the acceptor stem of tRNA. These results support the idea that GCN2 kinase function is activated under starvation conditions by binding uncharged tRNA to the domain related to histidyl-tRNA synthetase. The remaining GCN2C alleles map at the extreme C terminus, a domain required for ribosome association of the protein. Representative mutations in each domain were shown to depend on the phosphorylation site in eIF-2c for their effects on GCN4 expression and to increase the level of eIF-2a phosphorylation in the absence of amino acid starvation. Synthetic GCN2" double mutations show greater derepression ofGCN4 expression than the parental single mutations, and they have a slow-growth phenotype that we attribute to inhibition of general translation initiation. The phenotpes of the GCN2C alleles are dependent on GCNI and GCN3, indicating that these two positive regulators of GCN4 expression mediate the inhibitory effects on translation initiation associated with activation of the yeast eIF-2am kinase GCN2.Phosphorylation of the a subunit of translation initiation factor 2 (eIF-2a) in mammalian cells leads to inhibition of protein synthesis at the initiation step. Two different mammalian (eIF-2a) kinases have been identified: the doublestranded-RNA-activated inhibitor of translation (DAI) that is activated in response to viral infections and the hemecontrolled repressor (HCR) that is activated in reticulocytes by heme deficiency (for a review, see reference 26). Both kinases phosphorylate eIF-2a on the serine residue at position 51 (Ser-51) (9, 47). The phosphorylation of mammalian eIF-2a inhibits translation initiation by impairing the conversion of eIF-2-GDP to eIF-2-GTP at the completion of each initiation cycle, a reaction carried out by the guanine nucleotide exchange factor eIF-2B. Only the GTP-bound form of eIF-2 is able to form a ternary complex with the initiator tRNAMet and catalyze new rounds of translation initiation (41).GCN2 to increased synthesis of GCN4, a transcriptional activator of numerous genes encoding enzymes involved in amino acid biosynthesis. The kinase activity of GCN2 is required f...

We provide details of an inexpensive and rapid method for extraction of DNA from buccal swabs (including samples received through the mail) and from a range of other tissue samples. The procedure we have developed provides amounts of DNA adequate for several thousand polymerase chain reactions (PCRs), and we have validated its potential for long-term storage. Samples stored for > 4 years are of comparable concentration and provide as robust PCR templates as those tested immediately after extraction. The availability of this technology is of considerable significance in planning DNA banks from population collections and cohorts.

Polymorphisms in the serotonin transporter gene (5HTT) have been reported to be associated with neuroticism (emotionality) and with depression. A recent report of an association between 5HTT and neuroticism involved unselected samples and self-report questionnaires. We attempted to extend these findings using a selected extremes design and peer ratings. From a sample of 2085 individuals, each assessed on neuroticism by two independent peers, we selected 52 individuals from the top 5% and 54 individuals from the bottom 5%. No association was found for either a functional 44 bp insertion/deletion polymorphism in 5HTT regulatory sequence (5HTTLPR) or for a non-functional variable number tandem repeat 5HTT polymorphism.