Role of the ubiquitin-selective CDC-48/UFD-1/NPL-4 chaperone in DNA replication

Faithful transmission of genomic information requires tight spatiotemporal regulation of DNA replication factors. Posttranslational modifications, such as ubiquitylation, constitute a fast and effective mechanism to control such complex protein function. The AAA-ATPase CDC-48 plays an essential role in selective protein degradation triggered by ubiquitylation. While initial studies reported a crucial function of CDC-48 in the regulation of mitotic events, an essential role of the CDC-48/UFD-1/NPL-4 complex in DNA replication has been revealed in Caenorhabditis elegans (C. elegans) recently. Since the mechanistic details of CDC-48 activity remained to be elucidated, the identification of key substrates playing a vital role during DNA duplication is of major interest. This work describes a regulatory function of CDC-48 in the coordination of licensing and elongation events of DNA replication in C. elegans. In the licensing step of DNA replication, CDT-1 is loaded onto chromatin to subsequently promote the recruitment of relevant replication factors, including CDC-45 and the GINS complex. Throughout the elongation step CDC-45 and the GINS complex move with the replication fork, however, it is largely unknown how their chromatin association is controlled. CDC-48/UFD-1/NPL-4 deficient embryos stabilize the licensing factor CDT-1 exclusively on mitotic chromatin. Furthermore, worm embryos lacking cdc-48, ufd-1, or npl-4, show persistent chromatin association of CDC-45 and the GINS complex. Notably, the protein levels of CDC-45 and the GINS subunits SLD-5 and PSF-3 are not affected by ufd-1 and npl-4 (RNAi), suggesting a non-proteolytic regulation. Down-regulation of CDT-1 suppresses the chromatin association of the GINS complex in embryos disrupted for a functional CDC-48/UFD-1/NPL-4 complex. Hence, CDC-48 is supposed to orchestrate both, CDT-1 degradation and chromatin dissociation of the CDC-45/GINS complex. In conclusion, this work describes a novel role of the ubiquitin-selective chaperone CDC-48/UFD-1/NPL-4 in the context of chromatin associated processes. Elucidating the key substrates of CDC-48 during DNA replication illustrates a critical function in safeguarding genomic stability by an unexpected principle of target protein regulation

The dynamics of replication licensing in live Caenorhabditis elegans embryos

Accurate DNA replication requires proper regulation of replication licensing, which entails loading MCM-2-7 onto replication origins. In this paper, we provide the first comprehensive view of replication licensing in vivo, using video microscopy of Caenorhabditis elegans embryos. As expected, MCM-2-7 loading in late M phase depended on the prereplicative complex (pre-RC) proteins: origin recognition complex (ORC), CDC-6, and CDT-1. However, many features we observed have not been described before: GFP-ORC-1 bound chromatin independently of ORC-2-5, and CDC-6 bound chromatin independently of ORC, whereas CDT-1 and MCM-2-7 DNA binding was interdependent. MCM-3 chromatin loading was irreversible, but CDC-6 and ORC turned over rapidly, consistent with ORC/CDC-6 loading multiple MCM-2-7 complexes. MCM-2-7 chromatin loading further reduced ORC and CDC-6 DNA binding. This dynamic behavior creates a feedback loop allowing ORC/CDC-6 to repeatedly load MCM-2-7 and distribute licensed origins along chromosomal DNA. During S phase, ORC and CDC-6 were excluded from nuclei, and DNA was overreplicated in export-defective cells. Thus, nucleocytoplasmic compartmentalization of licensing factors ensures that DNA replication occurs only once

Clostridium difficile colitis in patients after kidney and pancreas-kidney transplantation

Limited data exist about Clostridium difficile colitis (CDC) in solid organ transplant patients. Between 1/1/99 and 12/31/02, 600 kidney and 102 pancreas–kidney allograft recipients were transplanted. Thirty-nine (5.5%) of these patients had CDC on the basis of clinical and laboratory findings. Of these 39 patients, 35 have information available for review. CDC developed at a median of 30 days after transplantation, and the patients undergoing pancreas–kidney transplantation had a slightly higher incidence of CDC than recipients of kidney alone (7.8% vs. 4.5%, P> 0.05). All but one patient presented with diarrhea. Twenty-four patients (64.9%) were diagnosed in the hospital, and CDC occurred during first hospitalization in 14 patients (40%). Treatment was with oral metronidazole (M) in 33 patients (94%)and M + oral vancomycin (M + V) in 2 patients. Eight patients had recurrent CDC, which occurred at a median of 30 days (range 15–314) after the first episode. Two patients (5.7%) developed fulminant CDC, presented with toxic megacolon, and underwent colectomy. One of them died; the other patient survived after colectomy. CDC should be considered as a diagnosis in transplant patients with history of diarrhea after antibiotic use, and should be treated aggressively before the infection becomes complicated

Fate specification and tissue-specific cell cycle control of the <i>Caenorhabditis elegans</i> intestine

Coordination between cell fate specification and cell cycle control in multicellular organisms is essential to regulate cell numbers in tissues and organs during development, and its failure may lead to oncogenesis. In mammalian cells, as part of a general cell cycle checkpoint mechanism, the F-box protein β-transducin repeat-containing protein (β-TrCP) and the Skp1/Cul1/F-box complex control the periodic cell cycle fluctuations in abundance of the CDC25A and B phosphatases. Here, we find that the Caenorhabditis elegans β-TrCP orthologue LIN-23 regulates a progressive decline of CDC-25.1 abundance over several embryonic cell cycles and specifies cell number of one tissue, the embryonic intestine. The negative regulation of CDC-25.1 abundance by LIN-23 may be developmentally controlled because CDC-25.1 accumulates over time within the developing germline, where LIN-23 is also present. Concurrent with the destabilization of CDC-25.1, LIN-23 displays a spatially dynamic behavior in the embryo, periodically entering a nuclear compartment where CDC-25.1 is abundant

Implementation experiences of NASTRAN on CDC CYBER 74 SCOPE 3.4 operating system

The implementation of the NASTRAN system on the CDC CYBER 74 SCOPE 3.4 Operating System is described. The flexibility of the NASTRAN system made it possible to accomplish the change with no major problems. Various sizes of benchmark and test problems, ranging from two hours to less than one minute CP time were run on the CDC CYBER SCOPE 3.3, Univac EXEC-8, and CDC CYBER SCOPE 3.4. The NASTRAN installation deck is provided

Citizenship and the Politics of Civic Driven Change

Nation states are premised on the legitimizing presence of a polity comprised of citizens. The politics of this relationship is central to discourse on how societies evolve. Yet in the discipline of international development studies the topic remains peripheral. Reasons can be found in conceptual confusion, in selectivity in donor thinking and policies towards civil society and in the growth-driven political economy of NGO-ism. Remedies for the political lacunae are being sought through a concerted focus on people's rights, citizenship and qualities of leadership that all show valuable progress. This chapter will examine a comprehensive complement to such efforts referred to as civic driven change (CDC). Originating in a grounded empirical approach, the constituent principles and elements of CDC offer a lens that can both sharpen and deepen insights and advance analysis of civic agency in socio-political processes. As an ontologically grounded normative proposition, CDC allows exposure and examination of 'uncivil' forces stemming from contending claims on citizenship. These factors are typically ignored or denied in an historical harmony model of societal change. A CDC narrative is illustrated by reference to contemporary examples of citizen action that play out at multiple sites of governance

Should outbreak response immunization be recommended for measles outbreaks in middle- and low-income countries? An update.

Measles caused mortality in >164,000 children in 2008, with most deaths occurring during outbreaks. Nonetheless, the impact and desirability of conducting measles outbreak response immunization (ORI) in middle- and low-income countries has been controversial. World Health Organization guidelines published in 1999 recommended against ORI in such settings, although recently these guidelines have been reversed for countries with measles mortality reduction goals

Comparison of the 2005 growth charts for Saudi children and adolescents to the 2000 CDC growth charts

Background and objectives: The 2000 CDC growth charts for the United States, a revision of the National Center for Health Statistics/World Health Organization (NCHS/WHO) growth charts, were released in 2002 to replace the NCHS/WHO charts. We evaluated the differences between the CDC growth charts and the Saudi 2005 reference to determine the implications of using the 2000 CDC growth charts in Saudi children and adolescents. Subjects and methods: The Saudi reference was based on a cross-sectional representative sample of the Saudi population of healthy children and adolescents from birth to 19 years of age. Measurements of the length/ stature, weight and head circumference were performed according to expert recommendations. The CDC charts from birth to 20 years were based on a cross-sectional representative national sample from five sources collected between 1963 and 1994. The data from the CDC study including the 3rd, 5th, 50th, 95th, and 97th percentiles were plotted against the corresponding percentiles on the Saudi charts for the weight for age, height for age, weight for height for children from 0 to 36 months and weight for age, stature for age and body mass index for children 2 to 19 years of age. Results: There were major differences between the two growth charts. The main findings were the upward shift of the lower percentiles of the CDC curves and the overlap or downward shift of the upper percentiles, especially for weight, weight for height, and BMI. Conclusions: The use of the 2000 CDC growth charts for Saudi children and adolescents increases the prevalence of undernutrition, stunting, and wasting, potentially leading to unnecessary referrals, investigations and parental anxiety. The increased prevalence of overweight and obesity is alarming and needs further investigation