23 research outputs found
Author correction: a novel atypical sperm centriole is functional during human fertilization
No full textIn the original version of this Article, the affiliation details for Jadranka Loncarek and Vito Mennella were incorrectly given as 'Cell Biology Program, The Hospital for Sick Children, Department of Biochemistry, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada' and 'Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute, 1050 Boyles Street, Frederick, MD, 21702, USA', respectively. This has now been corrected in both the PDF and HTML versions of the Article.</p
Substitution and redox reactions of heptarhenium cluster derivatives
No full textThe second-order rate constants for the reactivity of (Re\sb7C(CO)\sb{21}Rh(CO)\sb2) \sp{2-} towards phosphorus donors were determined. In order to correlate the results to electronic and/or steric effects, steric profiles relating log k\sb2 to an intrinsic reactivity an electronic parameter and a steric parameter were constructed. From differences in intrinsic reactivity for phosphines and phosphites, an intermediate configuration involving a bridging carbonyl has been proposed for the reaction of (Re\sb7C(CO)\sb{21}Rh(CO)\sb2) \sp{2-} with various phosphorus donors (PY\sb3).Nitrosylation of a series of mixed-metal heptarhenium clusters, (Re\sb7C(CO)\sb{21}ML\sb{\rm n}) \sp{2-}, gave the mono-substituted products, (Re\sb7C(CO)\sb{20}ML\sb{\rm n}\rbrack\sp-. A variety of spectroscopic techniques were used to characterize the reaction products. Variable temperature \sp{13}C NMR studies determined the solution structure of (Re\sb7C(CO)\sb{20}(NO)Rh(CO)\sb2) \sp-. From kinetic studies, the nitrosyl substituted cluster (Re\sb7C(CO)\sb{20}(NO)Rh(CO)\sb2) \sp- exhibits enhanced reactivity toward phosphorus ligands in comparison with (Re\sb7C(CO)\sb{21}Rh(CO)\sb2) \sp{2-}.The carbonyl ligands bound to (Re\sb7C(CO)\sb{21}Rh(CO)\sb2) \sp{2-} display unusual intermolecular and intramolecular exchange. Upon treatment with \sp{13}CO, (Re\sb7C(CO)\sb{21}Rh(CO)\sb2) \sp{2-} is selectively \sp{13}CO enriched to (\rm Re(CO)\sb3Re\sb6C(\sp{13}CO)\sb{18}Rh(\sp{13}CO)\sb2\rbrack \sp{2-}. A capping Re(CO)\sb3 moiety trans to the rhodium cap remains unenriched. Formation of the radical species (Re\sb7C(CO)\sb{21}Rh(CO)\sb2\rbrack\sp- by chemical oxidation results in complete carbonyl scrambling, which is revealed upon reduction to the parent cluster (\rm Re(\sp{13}CO)\sb3Re\sb6C(\sp{13}CO)\sb{18}Rh(\sp{13}CO)\sb 2\rbrack \sp{2-}. The selectively \sp{13}Co enriched cluster (Re(CO)\sb3Re\sb6C(\sp{13}CO)\sb{18}) \sp{2-} has been formed in a decapping reaction of (\rm Re(CO)\sb3Re\sb6C(\sp{13}CO)\sb{18}Rh(\sp{13}CO\sb2\rbrack \sp{2-} with excess PPh\sb3 in acetonitrile.Two-electron oxidation of (Re\sb7C(CO)\sb{21}) \sp{3-} in the presence of P(OPh)\sb3 affords (Re\sb7C(CO)\sb{21}(P(OPh)\sb3)) \sp-. \sp{13}C NMR indicates that this cluster exhibits partial charge separation. (Re\sb7C(CO)\sb{21}(P(OPh)\sb3)) \sp- decomposes in acetonitrile to form (Re\sb6C(CO)\sb{19}) \sp{2-} and (Re(CO)\sb3(P(OPh)\sb3)\sb2(NCCH\sb3)) \sp+, and therefore it represents a directly observed intermediate in a cluster decapping reaction.Made available in DSpace on 2011-05-07T12:36:21Z (GMT). No. of bitstreams: 2
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Acrosome components after intracytoplasmic sperm injection: the decondensation frontier
No full texthttp://www.sciencedirect.com/science/article/B6T6K-43CBFGC-14/1/c122d3f8e7188ef9ec4a133a8068995
Direct Differentiation of Human Pluripotent Stem Cells into Advanced Spermatogenic Cells: In Search of an In Vitro System to Model Male Factor Infertility
No full textFreeze-dried primate sperm retains early reproductive potential after intracytoplasmic sperm injection
No full textOocytes inseminated by intracytoplasmic sperm injection using fresh ejaculated or freeze-dried rhesus macaque sperm showed similar activation, sperm aster assembly, and male-female pronuclear apposition rates.http://www.sciencedirect.com/science/article/B6T6K-4NY4Y3G-3/1/b88ff573caaf542e4e022e698231d4b
Central spindle self-organization and cytokinesis in artificially activated sea urchin eggs
No full textAuthor Posting. © Marine Biological Laboratory, 2016. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 230, no.2 (2016): 85-95.The ability of microtubules of the mitotic apparatus
to control the positioning and initiation of the cleavage
furrow during cytokinesis was first established from
studies on early echinoderm embryos. However, the identity
of the microtubule population that imparts cytokinetic signaling
is unclear. The two main––and not necessarily mutually
exclusive–– candidates are the central spindle and the
astral rays. In the present study, we examined cytokinesis in
ammonia-activated sea urchin eggs, which lack paternally
derived centrosomes and undergo mitosis mediated by unusual
anastral, bipolar mini-spindles. Live cell imaging and
immunolabeling for microtubules and the centralspindlin
constituent and kinesin-related protein, MKLP1, demonstrated
that furrowing in ammonia-activated eggs was associated
with aligned arrays of centralspindlin-linked, opposed
bundles of antiparallel microtubules. These autonomous, zipper-
like arrays were not associated with a mitotic apparatus,
but did possess characteristics similar to the central spindle
region of control, fertilized embryos. Our results highlight the
self-organizing nature of the central spindle region and its
ability to induce cytokinesis-like furrowing, even in the absence
of a complete mitotic apparatus.This research was
supported by student/faculty summer research grants from
the Dickinson College Research and Development Committee
to JHH; Laura and Arthur Colwin Summer Research
Fellowships from the MBL to JHH and CBS; a National
Science Foundation Major Research Instrumentation grant
to JHH (MRI-0320606); and a NSF collaborative research
grant to JHH (MCB-1412688) and to CBS (MCB-
1412734)
The Implications of a Paternally Derived Centrosome During Human Fertilization: Consequences for Reproduction and the Treatment of Male Factor Infertility
No full text
