Regulating chromosomal movement by the cochaperone FKB-6 ensures timely pairing and synapsisBenjamin Alleva, Nathan Balukoff, Amy Peiper, Sarit SmolikoveDOI: 10.1083/jcb.201606126 | Published January 11, 2017Source/FonteAbstractIn meiotic prophase I, homologous chromosome pairing is promoted through chromosome movement mediated by nuclear envelope proteins, microtubules, and dynein. After proper homologue pairing has been established, the synaptonemal complex (SC) assembles along the paired homologues, stabilizing their interaction and allowing for crossing over to occur. Previous studies have shown that perturbing chromosome movement leads to pairing defects and SC polycomplex formation. We show that FKB-6 plays a role in SC assembly and is required for timely pairing and proper double-strand break repair kinetics. FKB-6 localizes outside the nucleus, and in its absence, the microtubule network is altered. FKB-6 is required for proper movement of dynein, increasing resting time between movements. Attenuating chromosomal movement in fkb-6 mutants partially restores the defects in synapsis, in agreement with FKB-6 acting by decreasing chromosomal movement. Therefore, we suggest that FKB-6 plays a role in regulating dynein movement by preventing excess chromosome movement, which is essential for proper SC assembly and homologous chromosome pairing.Submitted: 28 June 2016 Revision received 7 November 2016 Accepted: 29 December 2016http://www.rupress.org/terms/https://creativecommons.org/licenses/by-nc-sa/4.0/This article is distributed under the terms of an AttributionNoncommercialShare AlikeNo Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (AttributionNoncommercialShare Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).+++++Professores, pesquisadores e alunos de universidades publicas e privadas com acesso ao Portal de Periodicos CAPES/MEC podem ler gratuitamente este artigo do The Journal of Cell Biology e de mais 30.000 publicacoes cientificas.+++++PERGUNTA DESTE BLOGGER:Mero acaso, fortuita necessidade ou design inteligente??? Pyritized in situ trilobite eggs from the Ordovician of New York (Lorraine Group): Implications for trilobite reproductive biologyThomas A. Hegna1, Markus J. Martin2 and Simon A.F. Darroch3- Author Affiliations1Department of Geology, Western Illinois University, 113 Tillman Hall, 1 University Circle, Macomb, Illinois 61455, USA2371 Pawling Street, Watertown, New York 13601, USA3Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, Tennessee 37235, USASource/Fonte: Sciency Thoughts blogAbstractDespite a plethora of exceptionally preserved trilobites, trilobite reproduction has remained a mystery. No previously described trilobite has unambiguous eggs or genitalia preserved. This study reports the first occurrence of in situ preserved eggs belonging to Triarthrus eatoni (Hall, 1838) trilobites from the Lorraine Group in upstate New York, USA. Like other exceptionally preserved trilobites from the Lorraine Group, the complete exoskeletons are replaced with pyrite. The eggs are spherical to elliptical in shape, nearly 200 m in size, and are clustered in the genal area of the cephalon. The fact that the eggs are smaller than the earliest-known trilobite ontogenetic (protaspis) stage suggests that trilobites may have had an unmineralized preliminary stage in their ontogeny, and that the protaspis shield formed only after hatching. The eggs are only visible ventrally with no dorsal brood pouch or recognized sexual dimorphism. The location of the eggs is consistent with where modern female horseshoe crabs release their unfertilized eggs from the ovarian network within their head. Trilobites likely released their