ChemInform Abstract: Preuplotin (I), a Putative Biogenetic Precursor of the Euplotins, Bioactive Sesquiterpenoids of the Marine Ciliated Protist Euplotes crassus.

ChemInform ◽  
2010 ◽  
Vol 25 (18) ◽  
pp. no-no
Author(s):  
G. GUELLA ◽  
F. DINI ◽  
A. TOMEI ◽  
F. PIETRA
2002 ◽  
Vol 22 (16) ◽  
pp. 5859-5868 ◽  
Author(s):  
Saugata Ray ◽  
Zemfira Karamysheva ◽  
Libin Wang ◽  
Dorothy E. Shippen ◽  
Carolyn M. Price

ABSTRACT In the ciliate Euplotes crassus, millions of new telomeres are synthesized by telomerase and polymerase α-primase during macronuclear development in mated cells. Concomitant with de novo telomere formation, telomerase assembles into higher-order complexes of 550 kDa, 1,600 kDa, and 5 MDa. We show here that telomerase is physically associated with the lagging-strand replication machinery in these complexes. Antibodies against DNA primase precipitated telomerase activity from all three complexes from mated cells but not the 280-kDa telomerase complex from vegetatively growing cells. Moreover, when telomerase was affinity purified, primase copurified with enzyme from mated cells but not with the 280-kDa vegetative complex. Thus, the association of telomerase and primase is developmentally regulated. Intriguingly, PCNA (proliferating cell nuclear antigen) was also found in the 5-MDa complex from mated cells. We therefore speculate that this complex is a complete telomere synthesis machine, while the smaller complexes are assembly intermediates. The physical association of telomerase and primase explains the coordinate regulation of telomeric G- and C-strand synthesis and the efficiency of telomere addition in E. crassus.


1996 ◽  
Vol 43 (6) ◽  
pp. 442-452 ◽  
Author(s):  
MARY ELLEN JACOBS ◽  
LAWRENCE A. KLOBUTCHER

Author(s):  
Douglass F. Taber

Penaresidin A 3, isolated from the Okinawan marine sponge Penares sp., is a potent activator of actomyosin ATPase. B. V. Subba Reddy of the Indian Institute of Chemical Technology prepared (Tetrahedron Lett. 2014, 55, 49) the azetidine ring of 3 by mesyl­ation of the hydroxy sulfonamide 2, derived from 1, followed by cyclization. Allokainic acid 6 has become a useful tool for neurological studies. Radomir N. Saicic of the University of Belgrade found (Org. Lett. 2014, 16, 34) that the Tsuji–Trost cyclization of 4 to 5 proceeded with high diastereoselectivity, presumably by way of the enamine of the aldehyde. Floris P. J. T. Rutjes of Radboud University Nijmegen prepared (Org. Lett. 2014, 16, 2038) the starting material 7 for (−)-sedacryptine 9 via an enantioselective Mannich addition. The reagent of choice for the Aza–Achmatowicz rearrangement of 7 to 8 proved to be mCPBA. The intriguing tricyclic alkaloid (−)-lepistine 12 was isolated from the mushroom Clitocybe fasciculate. En route to the first-ever synthesis of 12, Satoshi Yokoshima and Tohru Fukuyama of Nagoya University cyclized (Org. Lett. 2014, 16, 2862) the gly­cidol-derived sulfonamide 10 to the azacycle 11. (+)-Septicine 15 is the biogenetic precursor to the phenanthrene alkaloid (+)-tylophorine. Stephen Hanessian of the Université de Montréal prepared (Org. Lett. 2014, 16, 232) 15 by condensing the proline-derived ketone 13 with the aldehyde 14. Mingji Dai of Purdue University elaborated (Angew. Chem. Int. Ed. 2014, 53, 3922) the amine 16 to the enone 17 by intramolecular Mannich alkylation followed by methylenation and allylic oxidation. Condensation with the sulfoxide 18 then delivered lyconadin C 19.


1980 ◽  
Vol 11 (40) ◽  
Author(s):  
P. RODIGHIERO ◽  
A. GUIOTTO ◽  
G. PASTORINI ◽  
P. MANZINI ◽  
F. DALL'ACQUA ◽  
...  

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