Characterization of Three Carbon- and Nitrogen-Rich Particles from Comet 81P/WILD

Comets may sample the early solar system s complement of volatile-forming elements - including C and N - more fully and reliably than do the terrestrial planets or asteroids. Until recently, all elemental analyses of unambiguously cometary material were carried out remotely. The return of the Stardust mission makes it possible to analyze documented material from P81/Wild 2 in the laboratory Wild 2 particles fragmented when they stopped in the aerogel collectors. We have studied three fragments thought to be rich in C and N by using several techniques: FTIR to characterize organic matter; synchrotron-induced x-ray fluorescence (SXRF) to determine Fe and certain element/Fe ratios; SEM to image sample morphology and to detect semiquantitatively Mg, Al, Si, Ca, and Fe; and nuclear reaction analysis (NRA) to measure C, N, O, and Si

Rariglanda jerseyensis a new ericalean fossil flower from the Late Cretaceous of New Jersey

A new species, Rariglanda jerseyensis, is described from well-preserved fusainized fossil flowers collected from the Late Cretaceous of New Jersey. Phylogenetic analyses and comparisons with extant and extinct taxa place R. jerseyensis within the monophyletic Ericales, sister to Clethraceae. The most distinctive feature of R. jerseyensis is a dense covering of conspicuous multicellular trichomes on the abaxial surface of the calyx. These multicellular trichomes appear to be glandular, and similar trichomes are found in several other, unrelated, Late Cretaceous fossils. In particular, the ericalean fossil Glandulocalyx upatoiensis bears the most similarity to R. jerseyensis, although differences in androecium and trichome characters clearly separate the two taxa. In addition, phylogenetic analyses confirm the position of G. upatoiensis within the Ericales, but place it within the sarracenioid clade, in a polytomy with Actinidiaceae and Roridulaceae. Past ecological studies associating trichomes with defense against herbivores and pathogens, coupled with the prevalence of multicellular trichomes on flowers among different lineages of fossils in the Cretaceous, suggest that glandular trichomes could have been an important adaptation against herbivore feeding during the Cretaceous.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Characterization of carbon- and nitrogen-rich particle fragments captured from comet 81P/Wild 2

We studied three Stardust fragments with infrared spectroscopy to characterize organic matter; with synchrotron-induced X-ray fluorescence to determine Fe contents and certain elemental ratios to iron; with scanning electron microscopy (SEM) to image sample morphology and to detect semiquantitatively Mg, Al, Si, Ca, and Fe; and with nuclear reaction analysis (NRA) to measure degrees C, N, O, and Si. A fourth fragment was analyzed by SEM only. Fragment C2054,0,35,21 from track 35 (hereafter C21) is extremely rich in degrees C and contains appreciable concentrations of Mg, Al, and Ca, but little Fe. Fragments C2054,0,35,23 (C23), C2044,0,41 (C41), and C2054,0,35,51,0 (C51), from tracks 35, 41, and 35, respectively, consist largely but not exclusively of aerogel. C23 contains Mg and finely dispersed S, but little Al, Ca or Fe. Pooled CI-normalized elemental ratios for C21, C23, and C41 are as follows: Ti/Fe, 5.0; Cr/Fe, 0.84; Mn/Fe, 0.97; Ni/Fe, 2.4; and Zn/Fe, 31. The enrichments in Ti and Zn may be related to the presence of aerogel. Minimum weight percentages of degrees C and N estimated without correcting for the presence of aerogel are 30 and 0.7 for C21; 2.8 and 0.2 for C23; 1.2 and 0.14 for C41. After corrections for the presence of aerogel containing 1.4 wt% degrees C and 0.02 wt% N, the corresponding results are 37 and 0.85 for C21; and 10 and 1 for C23; and ~1 and ~1, for C41 (The results for C41 have large uncertainties). These weight percentages are larger than or comparable to values for carbonaceous meteorites. degrees C/N atomic ratios without/without aerogel corrections are 51/51 for C21, 17/11 for C23, and 10/~1 for C41. Within the uncertainties these values are within the range for carbonaceous meteorites.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

The diaphragms of fenestrated endothelia:gatekeepers of vascular permeability and blood composition

Fenestral and stomatal diaphragms are endothelial subcellular structures of unknown function that form on organelles implicated in vascular permeability: fenestrae, transendothelial channels, and caveolae. PV1 protein is required for diaphragm formation in vitro. Here, we report that deletion of the PV1-encoding Plvap gene in mice results in the absence of diaphragms and decreased survival. Loss of diaphragms did not affect the fenestrae and transendothelial channels formation but disrupted the barrier function of fenestrated capillaries, causing a major leak of plasma proteins. This disruption results in early death of animals due to severe noninflammatory protein-losing enteropathy. Deletion of PV1 in endothelium, but not in the hematopoietic compartment, recapitulates the phenotype of global PV1 deletion, whereas endothelial reconstitution of PV1 rescues the phenotype. Taken together, these data provide genetic evidence for the critical role of the diaphragms in fenestrated capillaries in the maintenance of blood composition