The CENP-B homolog, Abp1, interacts with the initiation protein Cdc23 (MCM10) and is required for efficient DNA replication in fission yeast

Abp1, and the closely related Cbh1 and Cbh2 are homologous to the human centromere-binding protein CENP-B that has been implicated in the assembly of centromeric heterochromatin. Fission yeast cells lacking Abp1 show an increase in mini-chromosome instability suggesting that Abp1 is important for chromosome segregation and/or DNA synthesis. Here we show that Abp1 interacts with the DNA replication protein Cdc23 (MCM10) in a two-hybrid assay, and that the Δabp1 mutant displays a synthetic phenotype with a cdc23 temperature-sensitive mutant. Moreover, genetic interactions were also observed between abp1(+ )and four additional DNA replication initiation genes cdc18(+), cdc21(+), orc1(+), and orc2(+). Interestingly, we find that S phase is delayed in cells deleted for abp1(+ )when released from a G1 block. However, no delay is observed when cells are released from an early S phase arrest induced by hydroxyurea suggesting that Abp1 functions prior to, or coincident with, the initiation of DNA replication

Prevention of Nocturnal Elevation of Intraocular Pressure by Gene Transfer of Dominant-Negative RhoA in Rats

We developed a gene transfer tool for the control of nocturnal elevated intraocular pressure (IOP)

Haplotype affinities resolve a major component of goat (<i>Capra hircus</i>) MtDNA D-loop diversity and reveal specific features of the Sardinian stock

Goat mtDNA haplogroup A is a poorly resolved lineage absorbing most of the overall diversity and is found in locations as distant as Eastern Asia and Southern Africa. Its phylogenetic dissection would cast light on an important portion of the spread of goat breeding. The aims of this work were 1) to provide an operational definition of meaningful mtDNA units within haplogroup A, 2) to investigate the mechanisms underlying the maintenance of diversity by considering the modes of selection operated by breeders and 3) to identify the peculiarities of Sardinian mtDNA types. We sequenced the mtDNA D-loop in a large sample of animals (1,591) which represents a non-trivial quota of the entire goat population of Sardinia. We found that Sardinia mirrors a large quota of mtDNA diversity of Western Eurasia in the number of variable sites, their mutational pattern and allele frequency. By using Bayesian analysis, a distance-based tree and a network analysis, we recognized demographically coherent groups of sequences identified by particular subsets of the variable positions. The results showed that this assignment system could be reproduced in other studies, capturing the greatest part of haplotype diversity. We identified haplotype groups overrepresented in Sardinian goats as a result of founder effects. We found that breeders maintain diversity of matrilines most likely through equalization of the reproductive potential. Moreover, the relevant amount of inter-farm mtDNA diversity found does not increase proportionally with distance. Our results illustrate the effects of breeding practices on the composition of maternal gene pool and identify mtDNA types that may be considered in projects aimed at retrieving the maternal component of the oldest breeds of Sardinia.</br

Bone Marrow Transplantation Transfers Age-Related Susceptibility to Neovascular Remodeling in Murine Laser- Induced Choroidal Neovascularization

Citation: Espinosa-Heidmann DG, Malek G, Mettu PS, et al. Bone marrow transplantation transfers age-related susceptibility to neovascular remodeling in murine laser-induced choroidal neovascularization. Invest Ophthalmol Vis Sci. 2013;54:7439-7449. DOI:10.1167/iovs.13-12546 PURPOSE. Neovascular remodeling (NVR), the progression of small capillaries into large-caliber arterioles with perivascular fibrosis, represents a major therapeutic challenge in neovascular age-related macular degeneration (AMD). Neovascular remodeling occurs after laser-induced choroidal neovascularization (CNV) in aged but not young mice. Additionally, bone marrowderived cells, including macrophages, endothelial precursor cells, and mesenchymal precursor cells, contribute to CNV severity. In this study, we investigated the impact of aged bone marrow transplantation (BMT) on the degree of fibrosis, size, and vascular morphology of CNV lesions in a mouse model of laser-induced CNV. METHODS. Young (2 months) and old (16 months) mice were transplanted with green fluorescent protein (GFP)-labeled bone marrow isolated from either young or old donors. Laser CNV was induced 1 month following transplant, and eyes were analyzed via choroidal flat mounts and immunohistochemistry 1 month postlaser. The identity of cells infiltrating CNV lesions was determined using specific markers for the labeled transplanted cells (GFPþ), macrophages (F4/80þ), perivascular mesenchymal-derived cells (smooth muscle actin, SMAþ), and endothelial cells (CD31þ). RESULTS. Bone marrow transplantation from aged mice transferred susceptibility to NVR into young recipients. Inversely, transplantation of young marrow into old mice prevented NVR, preserving small size and minimal fibrosis. Mice with NVR demonstrated a greater relative contribution of marrow-derived SMAþ perivascular mesenchymal cells as compared to other cells. CONCLUSIONS. Our findings indicate that the status of bone marrow is an important determining factor of neovascular severity. Furthermore, we find that perivascular mesenchymal cells, rather than endothelial cells, derived from aged bone marrow may contribute to increased CNV severity in this murine model of experimental neovascularization

Haplotype Affinities Resolve a Major Component of Goat (Capra hircus) MtDNA D-Loop Diversity and Reveal Specific Features of the Sardinian Stock

Goat mtDNA haplogroup A is a poorly resolved lineage absorbing most of the overall diversity and is found in locations as distant as Eastern Asia and Southern Africa. Its phylogenetic dissection would cast light on an important portion of the spread of goat breeding. The aims of this work were 1) to provide an operational definition of meaningful mtDNA units within haplogroup A, 2) to investigate the mechanisms underlying the maintenance of diversity by considering the modes of selection operated by breeders and 3) to identify the peculiarities of Sardinian mtDNA types. We sequenced the mtDNA D-loop in a large sample of animals (1,591) which represents a non-trivial quota of the entire goat population of Sardinia. We found that Sardinia mirrors a large quota of mtDNA diversity of Western Eurasia in the number of variable sites, their mutational pattern and allele frequency. By using Bayesian analysis, a distance-based tree and a network analysis, we recognized demographically coherent groups of sequences identified by particular subsets of the variable positions. The results showed that this assignment system could be reproduced in other studies, capturing the greatest part of haplotype diversity

Studies on the two smallest subunits of DNA polymerase epsilon, and a DNA replication origin binding protein in fission yeast

Replication of chromosomal DNA is initiated at multiple origin sites called ARS elements. Before DNA synthesis can begin a number of proteins are recruited to these origins and sequentially assembled to form a pre-replicative complex. It is generally believed that, following activation by cyclin dependent kinases, DNA polymerases are loaded and DNA synthesis begins.The DNA polymerase epsilon complex (Pol epsilon) is one of three DNA polymerases required for eukaryotic chromosomal DNA replication and consists of four subunits that are evolutionary conserved. Interestingly, all the domains required for DNA synthesis activity, which reside in the N-terminal half of the large catalytic subunit, are dispensable for cell viability in yeast, indicating that Pol epsilon might be involved in other cellular processes. To investigate the function(s) of the DNA polymerase epsilon complex, I have identified and cloned the two smallest subunits of Pol epsilon in fission yeast, called Dpb3 and Dpb4. My results show that Dpb3 is essential for viability. Cells deleted for dpb3 display an elongated cdc phenotype distinctive of cell cycle defective mutants. However, analysis of their DNA content by FACS analysis indicate that cells arrest in G2 with a 2C DNA content and that a small number of these cells display a bi-nucleate or multi-nucleate phenotype indicating that in addition to its putative role in DNA replication, Dpb3 may have additional functions during the later stages of cytokinesis. On the other hand, Dpb4 is not essential; however, synthetic lethality with a number of known temperature sensitive initiation mutants suggests that Pol epsilon and its associated subunits participates in the early events of DNA replication and might be part of pre-replication and/or initiation complexes present at the origins. Both Dpb3 and Dpb4 localize to the nucleus; however, in the absence of Dpb3, Dpb4 is dispersed in the cytoplasm suggesting that Dpb3 is essential for the proper localization of Dpb4 and perhaps might be necessary for the entire Pol epsilon complex stability.Additionally, I investigated the DNA replication role of the origin binding protein, Abp1. This protein had been originally purified based on its ARS binding activity and we had later found a yeast-two hybrid interaction with the essential replication protein Cdc23. We have identified and cloned two fission yeast homologues of Abp1, called Abp3 and Cbh. Genetic analysis of double and triple mutants together with FACS analysis of triple mutant cells depleted of Abp1 show that these three proteins display a moderate S-phase defect.</p

Vorágine, une revue colombienne de la fin des années 80

Spiga Bannura Maria-Grazia. Vorágine, une revue colombienne de la fin des années 80. In: América : Cahiers du CRICCAL, n°15-16, 1996. Le discours culturel dans les revues latino-américaines, 1970-1990. pp. 213-220