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Lung megakaryocytes (Mks) are largely extravascular with an immune phenotype (1). Because bone marrow (BM) Mks are short lived, it has been assumed that extravascular lung Mks are constantly 'seeded' from the BM. To investigate lung Mk origins and how origin affects their functions, we developed methods to specifically label lung Mks using CFSE dye and biotin delivered via the oropharyngeal route. Labeled lung Mks were present for up to 4 months, while BM Mks had a lifespan of less than 1 week. In a parabiosis model, lung Mks were partially replaced over 1 month from a circulating source. Unlike tissue-resident macrophages, using [MDS1.sup.-Cre-ERT2] TdTomato mice, we found that lung Mks arose from hematopoietic stem cells. However, studies with FlkSwitch mTmG mice showed that lung Mks were derived from a Flt3-independent lineage that did not go through a multipotent progenitor. CFSE labeling to track lung Mk-derived platelets showed that approximately 10% of circulating platelets were derived from lung-resident Mks at steady state, but in sterile thrombocytopenia this was doubled (~20%). Lung-derived platelets were similarly increased in a malaria infection model (Plasmodium yoelii) typified by thrombocytopenia. These studies indicate that lung Mks arise from a Flt3- BM source, are long-lived, and contribute more platelets during thrombocytopenia., Introduction Platelets serve dual roles as a critical component of clot formation and as regulators of immune responses (1, 2). Activated platelets promote inflammation, while circulating resting platelets limit inflammation [...]

ELIZA HAYWOOD'S 1751 NOVEL, The History of Miss Betsy Thoughtless, announces the pertinent traits of her heroine in her surname: Thoughtless. Claiming that her heroine is without thought from the [...]

Research has been conducted on the chemoreceptor gene subset in Caenorhabditis elegans. The role of the daf-7 TGF-beta pathway in expression regulation of this subset has been invstigated and the results demonstrate that the expression of the individual chemoreceptor genes in C. elegans is subject to multiple regulation modes.

Myoblast city (mbc) may specifically regulate upstream Rac activity which in turn mediates several morphological processes in Drosophila embryonic formation. Eleven alleles of myoblast city were isolated in mutant embryos, which showed defects in dorsal closure, neural development, and myogenesis. Rac and Cdc42GTPases are regulated by several substances, and the results here suggest mbc serves as one regulator.

Many biological and physical variables affecting an animal's capacity to grow and reproduce have been identified (1). Efficient study and modeling of large numbers of variables simultaneously in a biological [...]