1,113 research outputs found
Cytoplasmic N-Terminal Protein Acetylation Is Required for Efficient Photosynthesis in Arabidopsis
No full textThe Arabidopsis atmak3-1 mutant was identified on the basis of a decreased effective quantum yield of photosystem II. In atmak3-1, the synthesis of the plastome-encoded photosystem II core proteins D1 and CP47 is affected, resulting in a decrease in the abundance of thylakoid multiprotein complexes. DNA array-based mRNA analysis indicated that extraplastid functions also are altered. The mutation responsible was localized to AtMAK3, which encodes a homolog of the yeast protein Mak3p. In yeast, Mak3p, together with Mak10p and Mak31p, forms the N-terminal acetyltransferase complex C (NatC). The cytoplasmic AtMAK3 protein can functionally replace Mak3p, Mak10p, and Mak31p in acetylating N termini of endogenous proteins and the L-A virus Gag protein. This result, together with the finding that knockout of the Arabidopsis MAK10 homolog does not result in obvious physiological effects, indicates that AtMAK3 function does not require NatC complex formation, as it does in yeast. We suggest that N-acetylation of certain chloroplast precursor protein(s) is necessary for the efficient accumulation of the mature protein(s) in chloroplasts
Reed Whittemore papers
No full textReed Whittemore (b. 1919) is a poet and emeritus professor of English at the University of Maryland, where he taught from 1967 to 1984. He also served twice as the Poetry Consultant for the Library of Congress. The author of a major biography of William Carlos Williams, he has also written numerous volumes of poems and essays. Whittemore's papers include correspondence, manuscripts, drafts, notes, galleys, proofs, scrapbooks, diaries, published materials, newspaper and magazine clippings, audiotapes, and photographs documenting his life, literary work, and teaching. Significant correspondents represented in the collection include Arthur Mizener and John Pauker
Prion Seeds Distribute throughout the Eyes of Sporadic Creutzfeldt-Jakob Disease Patients
No full textSporadic Creutzfeldt-Jakob disease (sCJD) is the most common prion disease in humans and has been iatrogenically transmitted through corneal graft transplantation. Approximately 40% of sCJD patients develop visual or oculomotor symptoms and may seek ophthalmological consultation. Here we used the highly sensitive real-time quaking-induced conversion (RT-QuIC) assay to measure postmortem prion seeding activities in cornea, lens, ocular fluid, retina, choroid, sclera, optic nerve, and extraocular muscle in the largest series of sCJD patient eyes studied by any assay to date. We detected prion seeding activity in 100% of sCJD eyes, representing three common sCJD subtypes, with levels varying by up to 4 log-fold among individuals. The retina consistently showed the highest seed levels, which in some cases were only slightly lower than brain. Within the retina, prion deposits were detected by immunohistochemistry (IHC) in the retinal outer plexiform layer in most sCJD cases, and in some eyes the inner plexiform layer, consistent with synaptic prion deposition. Prions were not detected by IHC in any other eye region. With RT-QuIC, prion seed levels generally declined in eye tissues with increased distance from the brain, and yet all corneas had prion seeds detectable. Prion seeds were also present in the optic nerve, extraocular muscle, choroid, lens, vitreous, and sclera. Collectively, these results reveal that sCJD patients accumulate prion seeds throughout the eye, indicating the potential diagnostic utility as well as a possible biohazard.IMPORTANCE Cases of iatrogenic prion disease have been reported from corneal transplants, yet the distribution and levels of prions throughout the eye remain unknown. This study probes the occurrence, level, and distribution of prions in the eyes of patients with sporadic Creutzfeldt-Jakob disease (sCJD). We tested the largest series of prion-infected eyes reported to date using an ultrasensitive technique to establish the prion seed levels in eight regions of the eye. All 11 cases had detectable prion seeds in the eye, and in some cases, the seed levels in the retina approached those in brain. In most cases, prion deposits could also be seen by immunohistochemical staining of retinal tissue; other ocular tissues were negative. Our results have implications for estimating the risk for iatrogenic transmission of sCJD as well as for the development of antemortem diagnostic tests for prion diseases
The repeat domain of the melanosome fibril proteinPmel17 forms the amyloid core promotingmelanin synthesis
No full text6 p.-4 fig,-1 tab.Pmel17 is a melanocyte protein necessary for eumelanin deposition 1 in mammals and found in melanosomes in a filamentous form. The luminal part of human Pmel17 includes a region (RPT) with 10 copies of a partial repeat sequence, pt.e.gttp.qv., known to be essential in vivo for filament formation. We show that this RPT region readily forms amyloid in vitro, but only under the mildly acidic conditions typical of the lysosome-like melanosome lumen, and the filaments quickly become soluble at neutral pH. Under the same mildly acidic conditions, the Pmel filaments promote eumelanin formation. Electron diffraction, circular dichroism, and solid-state NMR studies of Pmel17 filaments show that the structure is rich in beta sheet. We suggest that RPT is the amyloid core domain of the Pmel17 filaments so critical for melanin formation.This work was supported by the Intramural Program of the National Institute of Diabetes, Digestive and Kidney Diseases.Peer reviewe
Cypridina roxoensis Reed 1929
No full textCypridina roxoensis Reed 1929 (nomen dubium) Fig. 5 B Cyridina roxoensis Reed 1929: 67, pl. 4, fig. 13. Holotype Monotypic. Type locality Rox Rois No. 13 (Horizon A), Brasil, Upper Triassic. Material Specimen not examine herein. Distribution Upper Triassic, Brasil. Diagnosis Elongate with broadly rounded anterior and posterior margins and linear dorsal margin. Short vertical sulcus extends from hingeline to large central pit. Surface pitted and with low swellings. Length 3–4 mm. Comparisons Differs from M. hollandica in having straight dorsal margin. Remarks Not a Myodocopina. Resembles Paleozoic Leperditellidae. The senior author enquired about the specimen from the Sedgwick Museum, Cambridge, where Reed may have worked, but it was not in the museum records and could not be found in their collections (D. Pemberton & M. Lowe, email, 4 / 11 / 2006).Published as part of Kornicker, Louis S., Van, Barry W. M., Bakel, Fraaije, René H. B. & Jagt, John W. M., 2006, Revision of Mesozoic Myodocopina (Ostracoda) and a new genus and species, Mesoleberis hollandica, from the Upper Cretaceous of Belgium and The Netherlands, pp. 15-54 in Zootaxa 1246 on pages 45-46, DOI: 10.5281/zenodo.17293
Reed Dickerson’s Originalism — What it Contributes to Contemporary Constitutional Debate
No full textIn this article the author offers his personal gratitude for the work of Reed Dickerson, along with some thoughts on his important contributions to our understanding of the interpretive process. As a young scholar in need of help in grappling with the continuing debate over constitutional interpretation, the author turned, at the suggestion of colleagues, to Reed Dickerson’s impressive book on statutory interpretation. The hours spent attempting to ingest Reed’s thoughtful work were amply rewarded, and the author took the occasion of publishing an article on the original intent debate to refer in an initial footnote to his intellectual debt to Reed’s work and the illumination it had provided the author on the nature of legal interpretation in general. This occasion provides the author with the opportunity to expand on the reasons for his own conviction that serious constitutional thinkers should become well-acquainted with Professor Reed’s work
Anti-Prion Systems in Saccharomyces cerevisiae Turn an Avalanche of Prions into a Flurry
No full textPrions are infectious proteins, mostly having a self-propagating amyloid (filamentous protein polymer) structure consisting of an abnormal form of a normally soluble protein. These prions arise spontaneously in the cell without known reason, and their effects were generally considered to be fatal based on prion diseases in humans or mammals. However, the wide array of prion studies in yeast including filamentous fungi revealed that their effects can range widely, from lethal to very mild (even cryptic) or functional, depending on the nature of the prion protein and the specific prion variant (or strain) made by the same prion protein but with a different conformation. This prion biology is affected by an array of molecular chaperone systems, such as Hsp40, Hsp70, Hsp104, and combinations of them. In parallel with the systems required for prion propagation, yeast has multiple anti-prion systems, constantly working in the normal cell without overproduction of or a deficiency in any protein, which have negative effects on prions by blocking their formation, curing many prions after they arise, preventing prion infections, and reducing the cytotoxicity produced by prions. From the protectors of nascent polypeptides (Ssb1/2p, Zuo1p, and Ssz1p) to the protein sequesterase (Btn2p), the disaggregator (Hsp104), and the mysterious Cur1p, normal levels of each can cure the prion variants arising in its absence. The controllers of mRNA quality, nonsense-mediated mRNA decay proteins (Upf1, 2, 3), can cure newly formed prion variants by association with a prion-forming protein. The regulator of the inositol pyrophosphate metabolic pathway (Siw14p) cures certain prion variants by lowering the levels of certain organic compounds. Some of these proteins have other cellular functions (e.g., Btn2), while others produce an anti-prion effect through their primary role in the normal cell (e.g., ribosomal chaperones). Thus, these anti-prion actions are the innate defense strategy against prions. Here, we outline the anti-prion systems in yeast that produce innate immunity to prions by a multi-layered operation targeting each step of prion development
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