In C. elegans development, unfavorable growth conditions lead a larva to an arrested and enduring form called a dauer. To elucidate components upstream of DAF-7/TGF-beta in this control pathway, we isolated a mutant that was defective in daf-7 promoter::gfp reporter expression and showed an arrested (dauer-constitutive) phenotype. It has a new mutation in the daf-11 gene encoding a transmembrane guanylyl cyclase. We show that daf-11 gene and a related gene daf-21 act upstream of daf-7, and cilium-related genes che-2 and che-3 are placed between daf-11 and daf-7, in the genetic pathway controlling dauer formation. Expression of daf-11 cDNA by cell specific promoters suggests that daf-11 acts cell autonomously in ASI chemosensory neurons for daf-7 expression.

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We report a case of acute megakaryoblastic leukemia (AMKL) with antiplatelet antibody in a boy with Down syndrome. When the patient was admitted, his platelet count was 1.3 x 104/mm3 and antiplatelet antibody in the plasma was detected. Two months after admission, blasts, which showed positive reaction to both antiplatelet monoclonal antibody and platelet peroxidase, increased.acute megakaryoblastic leukemia ; Down syndrome ; antiplatelet antibody It is well known that children with Down syndrome are at increased risk of acute megakaryoblastic leukemia (AMKL). A number of such reported cases exhibited a preleukemic phase, characterized by thrombocytopenia (Beven and Rose 1982;Hayashi et al. 1986;Peeters and Poon 1987), but the etiology of thrombocytopenia has been unknown. We describe a case of AMKL in a boy with Down syndrome, following thrombocytopenia with antiplatelet antibody.The patient displayed physical stigmata of Down syndrome at birth, and chromosome analysis showed the. karyotype as 47,XY, + 21. At 20 months of age, he was admitted because of fever and generalized purpura. He had no history of blood transfusion. The results of hematologic examination were : red blood cells 323 x 104/mm3 ; platelets 1.3 x 104/mm3 ; white blood cells 4,400/mm3 with 19% blasts. In the bone marrow there were 8% blasts and a few (1/mm3) megakaryocytes, and we could not determine whether the blasts were leukemic or not. Bleeding time was prolonged (>5 min), but the results of coagulation studies were normal. Platelet associated IgG (PAIgG), measured by enzymelinked immunosorbent assay (Schiffer and Young 1983), was 181 ng/10' platelets. Antiplatelet antibody was detected by mixed passive hemagglutination test (Shibata et al. 1984) ( Table 1). And microlymphocytotoxicity test (Terasaki et al. 1978) showed negative reaction. Two months after admission, the blasts suddenly increased to 56% in the