Mutations in CDC45, Encoding an Essential Component of the Pre-initiation Complex, Cause Meier-Gorlin Syndrome and Craniosynostosis

DNA replication precisely duplicates the genome to ensure stable inheritance of genetic information. Impaired licensing of origins of replication during the G1 phase of the cell cycle has been implicated in Meier-Gorlin syndrome (MGS), a disorder defined by the triad of short stature, microtia, and a/hypoplastic patellae. Biallelic partial loss-of-function mutations in multiple components of the pre-replication complex (preRC; ORC1, ORC4, ORC6, CDT1, or CDC6) as well as de novo stabilizing mutations in the licensing inhibitor, GMNN, cause MGS. Here we report the identification of mutations in CDC45 in 15 affected individuals from 12 families with MGS and/or craniosynostosis. CDC45 encodes a component of both the pre-initiation (preIC) and CMG helicase complexes, required for initiation of DNA replication origin firing and ongoing DNA synthesis during S-phase itself, respectively, and hence is functionally distinct from previously identified MGS-associated genes. The phenotypes of affected individuals range from syndromic coronal craniosynostosis to severe growth restriction, fulfilling diagnostic criteria for Meier-Gorlin syndrome. All mutations identified were biallelic and included synonymous mutations altering splicing of physiological CDC45 transcripts, as well as amino acid substitutions expected to result in partial loss of function. Functionally, mutations reduce levels of full-length transcripts and protein in subject cells, consistent with partial loss of CDC45 function and a predicted limited rate of DNA replication and cell proliferation. Our findings therefore implicate the preIC as an additional protein complex involved in the etiology of MGS and connect the core cellular machinery of genome replication with growth, chondrogenesis, and cranial suture homeostasis

Concentração iônica plasmática e biliar do "curimbatá" Prochilodus scrofa Steindachner (Osteichthyes, Characiformes) em relação aos estádios de repouso e maduro do ciclo reprodutivo Plasmatic and biliar ionic concentration of the freshwater teleost fish Prochilodus scrofa Steindachner (Osteichthyes, Characiformes), in relation of maturation cycle

<abstract language="eng">Body fluid ionic content of fishes varies with ambient. Variations in the plasmatic ionic concentration have also been related with sex or maturation cycle, once that reproduction modifies metabolic processes. In fishes, the gallbladder is an important osmoregulatory organ. So, the present work has been focused on the relation of plasmatic and biliar electrolytes with sex and maturation cycle, of the teleost fish Prochilodus scrofa at the resting and mature stages of gonadal cycle. The animals (28 males and 30 females) were collected at Cachoeira de Emas (Pirassununga, São Paulo) and they were fasted for three days before the experiments. Deteminations of Na+, K+, Mg++, and Ca++ were made by spectophotometry and Cl- by microtitulation. Comparisons of ionic content between sex and maturation cycle were assessed using analysis of variance and Student-Newman-Keuls test. In this work it was seen that in males and females at resting and mature stages, there are no difference at ionic plasmatic content. K+ contents were higher in the bile of mature males than in resting ones. Mg++ biliar contents were higher in resting males than in resting and mature males. Na+, Ca++ e Cl- contents have no difference. Na+, K+, Ca++ and Mg++ contents were higher in the bile than in the plasma. Cl- content was higher in plasma than in bile. Variations related with proteic synthesis, and another metabolic processes during cycle, may be the reason of variations in the biliar ionic content

The feedback of massive stars on interstellar astrochemical processes

Astrochemistry is a discipline that studies physico-chemical processes in astrophysical environments. Such environments are characterized by conditions that are substantially different from those existing in usual chemical laboratories. Models which aim to explain the formation of molecular species in interstellar environments must take into account various factors, including many that are directly, or indirectly related to the populations of massive stars in galaxies. The aim of this paper is to review the influence of massive stars, whatever their evolution stage, on the physico-chemical processes at work in interstellar environments. These influences include the ultraviolet radiation field, the production of high energy particles, the synthesis of radionuclides and the formation of shocks that permeate the interstellar medium

SpSld3 Is Required for Loading and Maintenance of SpCdc45 on Chromatin in DNA Replication in Fission Yeast

Initiation of DNA replication in eukaryotic cells is regulated through the ordered assembly of replication complexes at origins of replication. Association of Cdc45 with the origins is a crucial step in assembly of the replication machinery, hence can be considered a target for the regulation of origin activation. To examine the process required for SpCdc45 loading, we isolated fission yeast SpSld3, a counterpart of budding yeast Sld3 that interacts with Cdc45. SpSld3 associates with the replication origin during G1–S phases and this association depends on Dbf4-dependent (DDK) kinase activity. In the corresponding period, SpSld3 interacts with minichromosome maintenance (MCM) proteins and then with SpCdc45. A temperature-sensitive sld3-10 mutation suppressed by the multicopy of the sna41(+) encoding SpCdc45 impairs loading of SpCdc45 onto chromatin. In addition, this mutation leads to dissociation of preloaded Cdc45 from chromatin in the hydroxyurea-arrested S phase, and DNA replication upon removal of hydroxyurea is retarded. Thus, we conclude that SpSld3 is required for stable association of Cdc45 with chromatin both in initiation and elongation of DNA replication. The DDK-dependent origin association suggests that SpSld3 is involved in temporal regulation of origin firing