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Fusarium verticillioides represents a major phytopathogenic threat to maize crops worldwide. In this study, we present genomic sequence data of a phytopathogen isolated from a maize stem that shows obvious signs of vascular rot. Using rigorous microbiological identification techniques, we correlated the disease symptoms observed in an affected maize region with the presence of the pathogen. Subsequently, the pathogen was cultured in a suitable fungal growth medium and extensive morphological characterization was performed. In addition, a pathogenicity test was carried out in a DCA model with three treatments and seven repetitions. De novo assembly from Illumina Novaseq 6000 sequencing yielded 456 contigs, which together constitute a 42.8 Mb genome assembly with a GC % content of 48.26. Subsequent comparative analyses were performed with other Fusarium genomes available in the NCBI database., (© 2024 The Author(s).)

Background and Aims: Trait-based frameworks assess plant survival strategies using different approaches. Some frameworks use functional traits to assign species to a priori defined ecological strategies. Others use functional traits as the central element of a species ecophysiological strategy. We compared these two approaches by asking: (1) what is the primary ecological strategy of three dominant co-occurring shrub species from inselbergs based on the CSR scheme, and (2) what main functional traits characterize the ecophysiological strategy of the species based on their use of carbon, water and light?, Methods: We conducted our study on a Colombian inselberg. In this extreme environment with multiple stressors (high temperatures and low resource availability), we expected all species to be stress tolerant (S in the CSR scheme) and have similar ecophysiological strategies. We measured 22 anatomical, morphological and physiological leaf traits., Key Results: The three species have convergent ecological strategies as measured by CSR (S, Acanthella sprucei; and S/CS, Mandevilla lancifolia and Tabebuia orinocensis) yet divergent resource-use strategies as measured by their functional traits. A. sprucei has the most conservative carbon use, risky water use and a shade-tolerant strategy. M. lancifolia has acquisitive carbon use, safe water use and a shade-tolerant strategy. T. orinocensis has intermediate carbon use, safe water use and a light-demanding strategy. Additionally, stomatal traits that are easy to measure are valuable to describe resource-use strategies because they are highly correlated with two physiological functions that are hard to measure: stomatal conductance and maximum photosynthesis per unit mass., Conclusions: The two approaches provide complementary information on species strategies. Plant species can co-occur in extreme environments, such as inselbergs, because they exhibit convergent primary ecological strategies but divergent ecophysiological strategies, allowing them to use limiting resources differently., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Condensin, an SMC (structural maintenance of chromosomes) protein complex, extrudes DNA loops using an ATP-dependent mechanism that remains to be elucidated. Here, we show how condensin activity alters the topology of the interacting DNA. High condensin concentrations restrain positive DNA supercoils. However, in experimental conditions of DNA loop extrusion, condensin restrains negative supercoils. Namely, following ATP-mediated loading onto DNA, each condensin complex constrains a DNA linking number difference (∆Lk) of -0.4. This ∆Lk increases to -0.8 during ATP binding and resets to -0.4 upon ATP hydrolysis. These changes in DNA topology do not involve DNA unwinding, do not spread outside the condensin-DNA complex and can occur in the absence of the condensin subunit Ycg1. These findings indicate that during ATP binding, a short DNA domain delimited by condensin is pinched into a negatively supercoiled loop. We propose that this loop is the feeding segment of DNA that is subsequently merged to enlarge an extruding loop. Such a "pinch and merge" mechanism implies that two DNA-binding sites produce the feeding loop, while a third site, plausibly involving Ycg1, might anchor the extruding loop., (©2022 The Authors. Published under the terms of the CC BY 4.0 license.)

Malignant pleural effusion and peritoneal carcinomatosis are frequent causes of effusion. Cytological evaluation (PAP-stained slides followed by immunocytochemistry, IHC, if applicable) is currently the gold standard for the diagnosis of malignant effusions, but its sensitivity varies between 40 and 80%, being a time-consuming technique. Although flow cytometry (FC) is not routinely used in the diagnosis or follow-up of nonhematopoietic neoplasms, it has the advantage of being rapidly applicable to fresh samples, potentially decreasing the time for the diagnosis. The main objective of this study was to assess the utility of FC as a confirmatory tool in the diagnosis of neoplastic effusions, based on the expression of EpCAM antibody in tumor cells versus the cytological evaluation. In this work 1,535 serous fluids were collected, of which 101 (68 pleural, 33 ascites) were selected through a screening algorithm and sent to the FC and cytological evaluation. Seventy-three of these samples (46 pleural, 27 ascites) were considered malignant as determined by clinical, cytological and radiological criteria. According to our data, 75% (55/73) of these samples were positive by Cytology/IHC and 74% (54/73) by FC. We noticed that, although the sensitivity, specificity, and area under the curve were similar, the turn-around time was shorter when using FC. Moreover, these results clearly improved by combining both techniques. We conclude that FC provides information about malignant effusions faster than immunohistochemical staining, and we believe that performing both techniques in parallel would improve diagnostic performance., (© 2020 International Clinical Cytometry Society.)

The educational use of daily-life contexts is considered a valuable strategy to promote meaningful science learning, since it facilitates the establishment of connections between previous knowledge, personal interests, and new learning. The aim of this work is to provide evidence to support the presence of gardens at educational centers, by assessing key science topics whose learning is promoted at the pre-school, primary, secondary, and university stages. To this end, we analyzed the paired graphic representations of "a garden" that students drew both before and after their participation in a garden-based learning program. Firstly, we obtained the frequency of appearance of every represented element, and afterward characterized the level of change between paired graphic representations. Sample size was of 24-19-25-29 pairs per stage, respectively. Across all stages, an overall improvement in students' graphic expression was observed, which can be attributed to their experience in the space. At the pre-school stage, the garden favored the establishment of some simple cause-effect relationships which were consolidated at the primary stage, and provided a climate of motivation and affectivity that was evident in the final drawings, given the enormous quantity of details represented, the level of the finished product, and the careful combination and variety of colors. The presence of elements related to water notably increased in final graphic representations from pre-school, primary, and secondary education, thus evidencing that the use of gardens facilitates an approach to responsible water management. At the university stage, students initially demonstrated good knowledge of conventional agriculture, while the gardening experience -which was based on permaculture practices- helped evolve their ideas toward an alternative model of cultivation. The most prevalent science learning across all stages was related to plant knowledge, particularly to their anatomical traits and diversity. Finally, the role of educational gardens as models for students was evidenced, which suggests the importance of teachers and institutions carefully considering which model to offer. Overall, our results support the legitimacy of incorporating gardens to educational centers, particularly for promoting contact with live plants and plant knowledge, and potentially for promoting contact with garden fauna and activities oriented toward learning about it., (Copyright © 2020 Eugenio-Gozalbo, Aragón and Ortega-Cubero.)

Introduction: We evaluated the value of hematopoietic progenitor cells (HPCs) counted in Sysmex XN analyzers to predict the mobilization and collection of CD34+ cells in apheresis for stem cell transplantation., Methods: Eighty patients who underwent stem cell transplantation were enrolled (50 autologous and 30 allogeneic). In the autologous group, patients were considered poor mobilizers when the CD34+ count was <10 × 10 6 /L or <20 × 10 6 /L in patients with multiple myeloma who were going to undergo two transplants. ROC curves were generated, and HPC cutoffs were calculated., Results: The correlation between the HPC and CD34+ cell counts was good. Two algorithms were proposed. In the first algorithm, samples collected the day before apheresis, negative and positive HPC cutoffs were selected to detect poor and good mobilization and, therefore, the need or not to administer plerixafor. In the second algorithm, samples collected pre-apheresis, the negative HPC cutoff was an indication to delay apheresis; an HPC higher than the optimal cutoff was an indication to start apheresis. When the HPC values were between these cutoffs, there was an indication to count CD34+ cells for a better decision-making. Finally, in samples collected pre-apheresis, HPC counts could be used to predict patients who would have poor CD34+ cell collections. In the allogeneic group, all the donors mobilized well, and very few needed two apheresis procedures., Conclusions: The HPC count is useful for decision-making in the management of patients subjected to apheresis procedures to collect peripheral blood stem cells., (© 2019 John Wiley & Sons Ltd.)

The role of Rad53 in response to a DNA lesion is central for the accurate orchestration of the DNA damage response. Rad53 activation relies on its phosphorylation by Mec1 and its own autophosphorylation in a manner dependent on the adaptor Rad9. While the mechanism behind Rad53 activation has been well documented, less is known about the processes that counteract its activity along the repair of a DNA adduct. Here, we describe that PP4 phosphatase is required to avoid Rad53 hyper-phosphorylation during the repair of a double-strand break, a process that impacts on the phosphorylation status of multiple factors involved in the DNA damage response. PP4-dependent Rad53 dephosphorylation stimulates DNA end resection by relieving the negative effect that Rad9 exerts over the Sgs1/Dna2 exonuclease complex. Consequently, elimination of PP4 activity affects resection and repair by single-strand annealing, defects that are bypassed by reducing Rad53 hyperphosphorylation. These results confirm that Rad53 phosphorylation is controlled by PP4 during the repair of a DNA lesion and demonstrate that the attenuation of its kinase activity during the initial steps of the repair process is essential to efficiently enhance recombinational DNA repair pathways that depend on long-range resection for their success., (© The Author(s) 2019. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Antimicrobial resistance (AMR) is a serious issue that could have severe consequences if steps are not taken. The nybomycin natural products have the potential to extend the clinical efficacy of the marketed fluoroquinolone class of antibiotics through a 'reverse antibiotic' approach. However, only very limited structure-activity relationships are known for these fascinating compounds, in part due to challenges with their synthesis. Here we report a new scalable and robust synthetic route to the nybomycin natural products to aid in the development of this series. Through this synthesis, we report the antibiotic activity of novel analogues of this family confirming the selectivity for fluoroquinolone resistant bacteria and potential future opportunities for further optimisation.

Mebendazole (MBZ), designated as a WHO essential drug, can exist in diverse solid forms and presents low absorption at the gastrointestinal level. Considering the potential of cyclodextrins to enhance the solubility and permeability of drugs, inclusion complexes of polymorphs A and C of MBZ with β‑cyclodextrin were obtained. The characterization of the complexes in solid state was performed by using a combination of experimental techniques including Fourier transform infrared spectroscopy, powder X-ray diffractometry and solid state nuclear magnetic resonance. Moreover, the effect of the binary complexes on their physical stability was evaluated. In addition, for a complete characterization of polymorphs A and C, one dimensional spectra and correlation nuclear magnetic resonance experiments were employed. Our physical studies showed that the inclusion complexes were new crystalline forms that induced shifts and broadening in the infrared and nuclear spectra. A molecular modelling analysis performed on the inclusion modes, demonstrated that the most favourable structure for the complex was the head down orientation. Moreover, the intermolecular interactions calculated for the complex with the atoms in molecules theory are in good agreement with the spectroscopic results. The inclusion complexes exhibited an increment of solubility in simulated physiological media. Furthermore, it was demonstrated that the complex formation did not affect the physical stability of the polymorphs., (Copyright © 2018. Published by Elsevier B.V.)

Background and Objectives: Percentages of blood CD19+CD5+ B cells and CD8+perforin+ T lymphocytes can predict response to Interferon (IFN)-beta treatment in relapsing-remitting multiple sclerosis (RRMS) patients. We aimed to standardize their detection in a multicenter study, prior to their implementation in clinical practice., Methods: Fourteen hospitals participated in the study. A reference centre was established for comparison studies. Peripheral blood cells of 105 untreated RRMS patients were studied. Every sample was analyzed in duplicate in the participating centre and in the reference one by flow cytometry. When needed, participating centres corrected fluorescence compensations and negative cut-off position following reference centre suggestions. Concordance between results obtained by participating centres and by reference one was evaluated by intraclass correlation coefficients (ICC) and Spearman correlation test. Centre performance was measured by using z-scores values., Results: After results review and corrective actions implementation, overall ICC was 0.86 (CI: 0.81-0.91) for CD19+CD5+ B cell and 0.89 (CI: 0.85-0.93) for CD8+ perforin+ T cell quantification; Spearman r was 0.92 (0.89-0.95; p <0.0001) and 0.92 (0.88-0.95; p <0.0001) respectively. All centres obtained z-scores≤0.5 for both biomarkers., Conclusion: Homogenous percentages of CD19+CD5+ B cells and CD8 perforin+ T lymphocytes can be obtained if suitable compensation values and negative cut-off are pre-established., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Smc5 and Smc6, together with the kleisin Nse4, form the heart of the enigmatic and poorly understood Smc5/6 complex, which is frequently viewed as a cousin of cohesin and condensin with functions in DNA repair. As novel functions for cohesin and condensin complexes in the organization of long-range chromatin architecture have recently emerged, new unsuspected roles for Smc5/6 have also surfaced. Here, I aim to provide a comprehensive overview of our current knowledge of the Smc5/6 complex, including its long-established function in genome stability, its multiple roles in DNA repair, and its recently discovered connection to the transcription inhibition of hepatitis B virus genomes. In addition, I summarize new research that is beginning to tease out the molecular details of Smc5/6 structure and function, knowledge that will illuminate the nuclear activities of Smc5/6 in the stability and dynamics of eukaryotic genomes.

In this work, a novel molecularly imprinted polymer (MIP) proposed as solid phase extraction sorbent was developed for the determination of propylparaben (PP) in diverse cosmetic samples. The use of parabens (PAs) is authorized by regulatory agencies as microbiological preservative; however, recently several studies claim that large-scale use of these preservatives can be a potential health risk and harmful to the environment. Diverse factors that influence on polymer synthesis were studied, including template, functional monomer, porogen and crosslinker used. Morphological characterization of the MIP was performed using SEM and BET analysis. Parameters affecting the molecularly imprinted solid phase extraction (MISPE) and elution efficiency of PP were evaluated. After sample clean-up, the analyte was analyzed by high performance liquid chromatography (HPLC). The whole procedure was validated, showing satisfactory analytical parameters. After applying the MISPE methodology, the extraction recoveries were always better than 86.15%; the obtained precision expressed as RSD% was always lower than 2.19 for the corrected peak areas. Good linear relationship was obtained within the range 8-500ngmL -1 of PP, r 2 =0.99985. Lower limits of detection and quantification after MISPE procedure of 2.4 and 8ngmL -1 , respectively were reached, in comparison with previously reported methodologies. The development of MISPE-HPLC methodology provided a simple an economic way for accomplishing a clean-up/preconcentration step and the subsequent determination of PP in a complex matrix. The performance of the proposed method was compared against C-18 and silica solid phase extraction (SPE) cartridges. The recovery factors obtained after applying extraction methods were 96.6, 64.8 and 0.79 for MISPE, C18-SPE and silica-SPE procedures, respectively. The proposed methodology improves the retention capability of SPE material plus robustness and possibility of reutilization, enabling it to be used for PP routine monitoring in diverse personal care products (PCP) and environmental samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Previous studies have developed methodologies for predicting the number of CD4+ cells from the total leukocyte and lymphocytes count based on mathematical methodologies, obtaining percentages of effectiveness prediction higher than 90% with a value of less than 5000 leukocytes., Objective: To improve the methodology probabilities prediction in 5000-9000 leukocytes ranges., Method: from sets A, B, C and D defined in a previous study, and based on CD4+ prediction established on the total number of leukocytes and lymphocytes, induction was performed using data from 10 patients with HIV, redefining the sets A and C that describe the lymphocytes behavior relative to leukocytes. Subsequently, we evaluated with previous research prediction probabilities parameters from a sample of 100 patients, calculating the belonging probability to each sample and organized in predetermined ranges leukocytes, of each of the sets defined, their unions and intersections. Then the same procedure was performed with the new sets and the probability values obtained with the refined method were compared with respect to previously defined, by measures of sensitivity (SENS) and Negative Predictive Value (NPV) for each range., Results: probabilities with values greater than 0.83 were found in five of the nine ranges inside the new sets. The probability for the set A∪C increased from 0.06 to 0.18 which means increases between 0.06 and 0.09 for the intersection (A∪C) ∩ (B∪D), making evident the prediction improvement with new sets defined., Conclusion: The results show that the new defined sets achieved a higher percentage of effectiveness to predict the CD4+ value cells, which represents a useful tool that can be proposed as a substitute for clinical values obtained by the flow cytometry., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Cohesin is a protein complex with key roles in chromosome biology, from chromatid segregation to DNA repair. Cohesin function is regulated by several posttranslational modifications, including phosphorylation, acetylation, ubiquitylation, and SUMOylation. Recent studies have shown that cohesin SUMOylation is essential for sister chromatid cohesion during normal cell cycle and in response to DNA damage. Posttranslational modification by the small ubiquitin-like modifier (SUMO) is a field in expansion, however, detecting SUMOylation can be challenging because the amount of modified substrates are usually low and de-conjugation during sample preparation often occurs. In this chapter we describe a method that can be adapted to different model organisms, and substrates to detect SUMOylation. We focus on cohesin and show that SUMOylation indeed occurs in most of the subunits of budding yeast cohesin.

Chromosome condensation is an essential morphological event required for successful DNA segregation during mitosis. The high level of genome compaction achieved during this process is attained by the evolutionary conserved condensin complex. Recently, several lines of evidences have demonstrated that the mitotic phosphatase Cdc14 is required to ensure condensin loading onto chromosomes. To date several approaches have been used in order to characterize condensin activity and regulation, however these techniques are time-consuming and require complex equipment. In this chapter we described an easy and reliable protocol to analyze Cdc14-dependent condensin loading onto specific genomic DNA regions by using a chromatin immunoprecipitation (ChIP) technique.

Sister chromatid intertwines (SCIs), or catenanes, are topological links between replicated chromatids that interfere with chromosome segregation. The formation of SCIs is thought to be a consequence of fork swiveling during DNA replication, and their removal is thought to occur because of the intrinsic feature of type II topoisomerases (Top2) to simplify DNA topology. Here, we report that SCIs are also formed independently of DNA replication during G 2 /M by Top2-dependent concatenation of cohesed chromatids due to their physical proximity. We demonstrate that, in contrast to G 2 /M, Top2 removes SCIs from cohesed chromatids at the anaphase onset. Importantly, SCI removal in anaphase requires condensin and coincides with the hyperactivation of condensin DNA supercoiling activity. This is consistent with the longstanding proposal that condensin provides a bias in Top2 function toward decatenation. A comprehensive model for the formation and resolution of toxic SCI entanglements on eukaryotic genomes is proposed., (Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.)

Condensin is a conserved chromosomal complex necessary to promote mitotic chromosome condensation and sister chromatid resolution during anaphase. Here, we report that yeast condensin binds to replicated centromere regions. We show that centromeric condensin relocalizes to chromosome arms as cells undergo anaphase segregation. We find that condensin relocalization is initiated immediately after the bipolar attachment of sister kinetochores to spindles and requires Polo kinase activity. Moreover, condensin localization during anaphase involves a higher binding rate on DNA and temporally overlaps with condensin's DNA overwinding activity. Finally, we demonstrate that topoisomerase 2 (Top2) is also recruited to chromosome arms during anaphase in a condensin-dependent manner. Our results uncover a functional relation between condensin and Top2 during anaphase to mediate chromosome segregation., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

The dynamics of forest ecosystems worldwide have been driven largely by climatic teleconnections. El Niño-Southern Oscillation (ENSO) is the strongest interannual variation of the Earth's climate, affecting the regional climatic regime. These teleconnections may impact plant phenology, growth rate, forest extent, and other gradual changes in forest ecosystems. The objective of this study was to investigate how Pinus cooperi populations face the influence of ENSO and regional microclimates in five ecozones in northwestern Mexico. Using standard dendrochronological techniques, tree-ring chronologies (TRI) were generated. TRI, ENSO, and climate relationships were correlated from 1950-2010. Additionally, multiple regressions were conducted in order to detect those ENSO months with direct relations in TRI (p < 0.1). The five chronologies showed similar trends during the period they overlapped, indicating that the P. cooperi populations shared an interannual growth variation. In general, ENSO index showed correspondences with tree-ring growth in synchronous periods. We concluded that ENSO had connectivity with regional climate in northern Mexico and radial growth of P. cooperi populations has been driven largely by positive ENSO values (El Niño episodes).

The only canonical Holliday junction (HJ) resolvase identified in eukaryotes thus far is Yen1/GEN1. Nevertheless, Yen1/GEN1 appears to have a minor role in HJ resolution, and, instead, other structure-specific endonucleases (SSE) that recognize branched DNA play the leading roles, Mus81-Mms4/EME1 being the most important in budding yeast. Interestingly, cells tightly regulate the activity of each HJ resolvase during the yeast cell cycle. Thus, Mus81-Mms4 is activated in G 2/M, while Yen1 gets activated shortly afterwards. Nevertheless, cytological studies have shown that Yen1 is sequestered out of the nucleus when cyclin-dependent kinase activity is high, i.e., all of the cell cycle but G 1. We here show that the mitotic master phosphatase Cdc14 targets Yen1 to the nucleus in early anaphase through the FEAR network. We will further show that this FEAR-mediated Cdc14-driven event is sufficient to back-up Mus81-Mms4 in removing branched DNA structures, which are especially found in the long chromosome arms upon replication stress. Finally, we found that MEN-driven Cdc14 re-activation in late anaphase is essential to keep Yen1 in the nucleus until the next G 1. Our results highlight the essential role that early-activated Cdc14, i.e., through the FEAR network, has in removing all kind of non-proteinaceous linkages that preclude faithful sister chromatid segregation in anaphase. In addition, our results support the general idea of Yen1 acting as a last resource endonuclease to deal with any remaining HJ that might compromise genetic stability during chromosome segregation.

Studying interphase chromosome arrangements at the molecular level can provide important details on the function and coordination of many metabolic processes that take place on DNA, such as transcription or DNA repair. The chromosome conformation capture (3C) methodology was originally developed in yeast to study the interphase organization of a single-yeast chromosome. 3C assays allow the identification of physical interactions between distant DNA segments and thus provide detailed information on the folding of chromatin in the native cellular state. Since its initial development, the technique has been used to advance our understanding of the folding of gene loci and has yielded important discoveries, like the demonstration that distant transcriptional regulatory elements interact with their target promoters through chromatin loops. The 3C method uses formaldehyde cross-linking to covalently link interacting chromatin segments in intact cells. After chromatin digestion and ligation of cross-linked fragments, the frequency of interaction between distant DNA elements can be quantified. However, the design, analysis, and controls used are critical when using 3C. In this chapter, we describe the general protocol for 3C analysis and demonstrate it through analysis of interactions in repetitive sequences of the ribosomal gene array of Saccharomyces cerevisiae.

DNA double-strand break repair is critical for cell viability and involves highly coordinated pathways to restore DNA integrity at the lesion. An early event during homology-dependent repair is resection of the break to generate progressively longer 3' single-strand tails that are used to identify suitable templates for repair. Sister chromatids provide near-perfect sequence homology and are therefore the preferred templates during homologous recombination. To provide a bias for the use of sisters as donors, cohesin--the complex that tethers sister chromatids together--is recruited to the break to enforce physical proximity. Here we show that DNA breaks promote dissociation of cohesin loaded during the previous S phase in budding yeast, and that damage-induced dissociation of cohesin requires separase, the protease that dissolves cohesion in anaphase. Moreover, a separase-resistant allele of the gene coding for the α-kleisin subunit of cohesin, Mcd1 (also known as Scc1), reduces double-strand break resection and compromises the efficiency of repair even when loaded during DNA damage. We conclude that post-replicative DNA repair involves cohesin dissociation by separase to promote accessibility to repair factors during the coordinated cellular response to restore DNA integrity.

Background: Cohesion between sister chromatids is fundamental to ensure faithful chromosome segregation during mitosis and accurate repair of DNA damage postreplication. At the molecular level, cohesion establishment involves two defined events, a chromatin binding step and a chromatid entrapment event driven by posttranslational modifications on cohesin subunits., Results: Here, we show that modification by the small ubiquitin-like protein (SUMO) is required for sister chromatid tethering after DNA damage. We find that all subunits of cohesin become SUMOylated upon exposure to DNA damaging agents or presence of a DNA double-strand break. We have mapped all lysine residues on cohesin's α-kleisin subunit Mcd1 (Scc1) where SUMO can conjugate. We demonstrate that Mcd1 SUMOylation-deficient alleles are still recruited to DSB-proximal regions but are defective in tethering sister chromatids and consequently fail to establish damage-induced cohesion both at DSBs and undamaged chromosomes. Moreover, we demonstrate that the bulk of Mcd1 SUMOylation in response to damage is carried out by the SUMO E3 ligase Nse2, a subunit of the related Smc5-Smc6 complex. SUMOylation occurs in cells with compromised Chk1 kinase activity, necessary for known posttranslational modifications on Mcd1, required for damage-induced cohesion., Conclusions: These findings demonstrate that SUMOylation of Mcd1 is a novel prerequisite for the establishment of DNA damage-induced cohesion at DSB-proximal regions and cohesion-associating regions (CARs) genome-wide., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The essential oils (EOs) of two populations of Azorella cryptantha (Clos) Reiche, a native species from San Juan Province, were obtained by hydrodistillation in a Clevenger-type apparatus and characterized by GC-FID and GC/MS analyses. The compounds identified amounted to 92.3 and 88.7% of the total oil composition for A. cryptantha from Bauchaceta (Ac-BAU) and Agua Negra (Ac-AN), respectively. The EO composition for the two populations was similar, although with differences in the identity and content of the main compounds and also in the identity of minor components. The main compounds of the Ac-BAU EO were α-pinene, α-thujene, sabinene, δ-cadinene, δ-cadinol, trans-β-guaiene, and τ-muurolol, while α-pinene, α-thujene, β-pinene, γ-cadinene, τ-cadinol, δ-cadinene, τ-muurolol, and a not identified compound were the main constituents of the Ac-AN EO, which also contained 3.0% of oxygenated monoterpenes. The repellent activity on Triatoma infestans nymphs was 100 and 92% for the Ac-AN and Ac-BAU EOs, respectively. Regarding the toxic effects on Ceratitis capitata, the EOs were very active with LD(50) values lower than 11 μg/fly. The dermatophytes Microsporum gypseum, Trichophyton rubrum, and T. mentagrophytes and the bacterial strains Escherichia coli LM(1), E. coli LM(2), and Yersinia enterocolitica PI were more sensitive toward the Ac-AN EO (MIC 125 μg/ml) than toward the Ac-BAU EO. This is the first report on the composition of A. cryptantha EO and its anti-insect and antimicrobial properties., (Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.)

We address several questions on the behavior of a numerical model recently introduced to study seismic phenomena, which includes relaxation in the plates as a key ingredient. First, we make an analysis of the scaling of the largest events with system size and show that, when parameters are appropriately interpreted, the typical size of the largest events scale as the system size, without the necessity to tune any parameter. Second, we show that the temporal activity in the model is inherently nonstationary and obtain from here justification and support for the concept of a "seismic cycle" in the temporal evolution of seismic activity. Finally, we ask for the reasons that make the model display a realistic value of the decaying exponent b in the Gutenberg-Richter law for the avalanche size distribution. We explain why relaxation induces a systematic increase in b from its value b≃0.4 observed in the absence of relaxation. However, we have not been able to justify the actual robustness of the model in displaying a consistent b value around the experimentally observed value b≃1.

The compaction of chromatin that occurs when cells enter mitosis is probably the most iconic process of dividing cells. Mitotic chromosomal compaction or 'condensation' is functionally linked to resolution of chromosomal intertwines, transcriptional shut-off and complete segregation of chromosomes. At present, understanding of the molecular events required to convert interphase chromatin into mitotic chromosomes is limited. Here, we review recent advances in the field, focusing on potential chromosomal compaction mechanisms and their importance to chromosome segregation. We propose a model of how metaphase chromosomes could be shaped based on the enzymatic activities of condensin and topoisomerase II in overwinding and relaxation of the DNA fiber during mitosis. We suggest that condensin overwinding is an important requirement for intertwine resolution by topoisomerase II and, together with the inhibition of transcription, contributes to cytological mitotic chromosome appearance or 'condensation'., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The resolution of chromosomes during anaphase is a key step in mitosis. Failure to disjoin chromatids compromises the fidelity of chromosome inheritance and generates aneuploidy and chromosome rearrangements, conditions linked to cancer development. Inactivation of topoisomerase II, condensin, or separase leads to gross chromosome nondisjunction. However, the fate of cells when one or a few chromosomes fail to separate has not been determined. Here, we describe a genetic system to induce mitotic progression in the presence of nondisjunction in yeast chromosome XII right arm (cXIIr), which allows the characterisation of the cellular fate of the progeny. Surprisingly, we find that the execution of karyokinesis and cytokinesis is timely and produces severing of cXIIr on or near the repetitive ribosomal gene array. Consequently, one end of the broken chromatid finishes up in each of the new daughter cells, generating a novel type of one-ended double-strand break. Importantly, both daughter cells enter a new cycle and the damage is not detected until the next G2, when cells arrest in a Rad9-dependent manner. Cytologically, we observed the accumulation of damage foci containing RPA/Rad52 proteins but failed to detect Mre11, indicating that cells attempt to repair both chromosome arms through a MRX-independent recombinational pathway. Finally, we analysed several surviving colonies arising after just one cell cycle with cXIIr nondisjunction. We found that aberrant forms of the chromosome were recovered, especially when RAD52 was deleted. Our results demonstrate that, in yeast cells, the Rad9-DNA damage checkpoint plays an important role responding to compromised genome integrity caused by mitotic nondisjunction., Competing Interests: The authors have declared that no competing interests exist.

Kinases and phosphatases regulate messenger RNA synthesis through post-translational modification of the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II (ref. 1). In yeast, the phosphatase Cdc14 is required for mitotic exit(2,3) and for segregation of repetitive regions(4). Cdc14 is also a subunit of the silencing complex RENT (refs 5,6), but no roles in transcriptional repression have been described. Here we report that inactivation of Cdc14 causes silencing defects at the intergenic spacer sequences of ribosomal genes during interphase and at Y' repeats in subtelomeric regions during mitosis. We show that the role of Cdc14 in silencing is independent of the RENT deacetylase subunit Sir2. Instead, Cdc14 acts directly on RNA polymerase II by targeting CTD phosphorylation at Ser 2 and Ser 5. We also find that the role of Cdc14 as a CTD phosphatase is conserved in humans. Finally, telomere segregation defects in cdc14 mutants(4) correlate with the presence of subtelomeric Y' elements and can be rescued by transcriptional inhibition of RNA polymerase II.

In this issue of Molecular Cell, Farcas et al. (2011) demonstrate that intertwining between sister chromatids at metaphase is much more significant than previously thought and, remarkably, show that it depends on cohesin., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The injection of bulking agents has been described as a useful treatment of urinary and fecal incontinence. Among them, silicone implants have shown benefits in patients with internal anal sphincter (IAS) injury. We describe two patients with a history of hemorrhoidectomy and IAS injuries, which underwent placement of silicone implants. The implants were inserted into the intersphincteric space and the IAS under ultrasound guidance. The Wexner continente score fell from 17 and 19 before treatment, to 6 and 8 at six months follow up, respectively. Patients had no postoperative complications or implants migration. In our patients, injection of silicone implants improved fecal continence score, without postoperative complications or implants migration at six month follow up.

The antifungal, antibacterial, and insect-repellent activities of the essential oils (EOs) of Acantholippia seriphioides, Artemisia mendozana, Gymnophyton polycephalum, Satureja parvifolia, Tagetes mendocina, and Lippia integrifolia, collected in the Central Andes area, province of San Juan, Argentina, were investigated. The dermatophytes Microsporum gypseum, Trichophyton mentagrophytes, and T. rubrum were inhibited by the EOs of G. polycephalum, L. integrifolia, and S. parvifolia, with minimum inhibitory concentrations (MICs) between 31.2 and 1000 μg/ml. Moreover, all EOs presented moderate activity against the bacteria tested, and the L. integrifolia and G. polycephalum EOs showed excellent repellent properties against Triatoma infestans, the Chagas disease vector, with repellency values between 60 and 100%. The A. seriphioides, G. polycephalum, and L. integrifolia EOs, obtained by hydrodistillation, were characterized by GC-FID and GC/MS analyses. The highest number of components (40) was identified in L. integrifolia EO, which, along with that of A. seriphioides, contained important amounts of oxygenated monoterpenes (44.35 and 29.72%, resp.). Thymol (27.61%) and carvacrol (13.24%) were the main components of A. seriphioides EO, and borneol, lippifoli-1(6)-en-5-one, and terpinen-4-ol (>8.5%) were the principal compounds of L. integrifolia EO. These results support the idea that oxygenated monoterpenes are the bioactive fractions of the EOs. Finally, the study shows that these Andean species might be used to treat superficial fungal infections and to improve the local Chagas disease situation by vector-control., (Copyright © 2011 Verlag Helvetica Chimica Acta AG, Zürich.)

DNA topoisomerase II completely removes DNA intertwining, or catenation, between sister chromatids before they are segregated during cell division. How this occurs throughout the genome is poorly understood. We demonstrate that in yeast, centromeric plasmids undergo a dramatic change in their topology as the cells pass through mitosis. This change is characterized by positive supercoiling of the DNA and requires mitotic spindles and the condensin factor Smc2. When mitotic positive supercoiling occurs on decatenated DNA, it is rapidly relaxed by topoisomerase II. However, when positive supercoiling takes place in catenated plasmid, topoisomerase II activity is directed toward decatenation of the molecules before relaxation. Thus, a topological change on DNA drives topoisomerase II to decatenate molecules during mitosis, potentially driving the full decatenation of the genome.

Efficient repair of DNA double-stranded breaks (DSB) requires a coordinated response at the site of lesion. Nucleolytic resection commits repair towards homologous recombination, which preferentially occurs between sister chromatids. DSB resection promotes recruitment of the Mec1 checkpoint kinase to the break. Rtt107 is a target of Mec1 and serves as a scaffold during repair. Rtt107 plays an important role during rescue of damaged replication forks, however whether Rtt107 contributes to the repair of DSBs is unknown. Here we show that Rtt107 is recruited to DSBs induced by the HO endonuclease. Rtt107 phosphorylation by Mec1 and its interaction with the Smc5-Smc6 complex are both required for Rtt107 loading to breaks, while Rtt107 regulators Slx4 and Rtt101 are not. We demonstrate that Rtt107 has an effect on the efficiency of sister chromatid recombination (SCR) and propose that its recruitment to DSBs, together with the Smc5-Smc6 complex is important for repair through the SCR pathway.

Meiosis, a specialized cell division with a single cycle of DNA replication round and two consecutive rounds of nuclear segregation, allows for the exchange of genetic material between parental chromosomes and the formation of haploid gametes. The structural maintenance of chromosome (SMC) proteins aid manipulation of chromosome structures inside cells. Eukaryotic SMC complexes include cohesin, condensin and the Smc5-Smc6 complex. Meiotic roles have been discovered for cohesin and condensin. However, although Smc5-Smc6 is known to be required for successful meiotic divisions, the meiotic functions of the complex are not well understood. Here we show that the Smc5-Smc6 complex localizes to specific chromosome regions during meiotic prophase I. We report that meiotic cells lacking Smc5-Smc6 undergo catastrophic meiotic divisions as a consequence of unresolved linkages between chromosomes. Surprisingly, meiotic segregation defects are not rescued by abrogation of Spo11-induced meiotic recombination, indicating that at least some chromosome linkages in smc5-smc6 mutants originate from other cellular processes. These results demonstrate that, as in mitosis, Smc5-Smc6 is required to ensure proper chromosome segregation during meiosis by preventing aberrant recombination intermediates between homologous chromosomes.

Ribosome biogenesis requires transcription of structural RNAs. In budding yeast, ribosomal units contain both 35S and 5S RNA genes separated by intergenic spacer sequences (IGS) that are transcribed by RNAP-II. IGS transcripts cause instability by promoting unequal sister chromatid recombination between repeats and are thus rapidly degraded by the exosome. Whether RNAP-II within IGS regions plays any functional role is unknown. Here we demonstrate that the bulk of RNAP-II bound to IGS sites is blocked for elongation and hence remains in a poised or stalled configuration. We describe a novel role for these stalled RNAP-II complexes in the formation of cis-interactions between the IGS of rDNA. We show that this function separates 35S and 5S RNA genes into polymerase-specific chromatin loops and demonstrate that removal of stalled RNAP-II complexes causes displacement of RNAP-III from the 5S gene region and transcriptional downregulation of 5S rRNA by spreading of RNAP-I. We conclude that stalled RNAP-II plays an active role in the cis-organisation of ribosomal repeats providing domains of polymerase specificity in the nucleolar transcription environment.

Mitotic chromosome segregation requires the removal of physical connections between sister chromatids. In addition to cohesin and topological entrapments, sister chromatid separation can be prevented by the presence of chromosome junctions or ongoing DNA replication. We will collectively refer to them as DNA-mediated linkages. Although this type of structures has been documented in different DNA replication and repair mutants, there is no known essential mechanism ensuring their timely removal before mitosis. Here, we show that the dissolution of these connections is an active process that requires the Smc5/6 complex, together with Mms21, its associated SUMO-ligase. Failure to remove DNA-mediated linkages causes gross chromosome missegregation in anaphase. Moreover, we show that Smc5/6 is capable to dissolve them in metaphase-arrested cells, thus restoring chromosome resolution and segregation. We propose that Smc5/6 has an essential role in the removal of DNA-mediated linkages to prevent chromosome missegregation and aneuploidy.

The numbers of different types of ovarian follicles (developing, degenerating and postovulatory follicles) were estimated in bluefin tuna Thunnus thynnus using two stereological procedures: the model-based method of Weibel & Gomez, which has become a tool of broad application in the quantification of oocytes in fishes, and the assumption-free 'disector' (sic) method of Sterio. The estimates of developing follicles (follicles containing lipid-stage, vitellogenic and migratory-nucleus oocytes) made by the model-based method tended to be lower than those obtained with the disector, though significant differences were not observed except for vitellogenic follicles. Counts of atretic follicles by the model-based method were higher than those made using the disector, the differences being remarkable between both techniques, particularly in the case of beta-atresia, where the statistical analysis indicated significantly unequal estimations with the two methods. In contrast, the amount of postovulatory follicles estimated by the disector, which would stand for the realized batch fecundity, was somewhat larger than that calculated with the model-based method.

The presence of inactive units in tandem arrays of ribosomal genes (rDNA) has been linked to increased transcriptional capacity, but a recent study indicates that inactive units are necessary for sister chromatid cohesion and genetic stability of rDNA., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The fidelity of chromosome inheritance is of paramount importance to all living organisms. In eukaryotic cells, the strategy to ensure physical segregation of chromosomes to daughter cells relies on two basic steps ordered in time: an initial linkage, or cohesion, of sister chromatids and its timely and complete dissolution during anaphase. The current view is that these two basic steps are accomplished around the regulation of a protein complex called cohesin that serves as "clamp brackets" distributed at intervals throughout the genome. However, many of the DNA metabolic activities during interphase also produce physical linking of chromatids. For example, during replication, intertwines between sister chromatids are formed. Here, we review our understanding of the processes that generate physical linkages between chromatids and discuss potential mechanisms that are involved in the removal of such obstacles to the complete physical separation of chromatids at anaphase.

Rectal affection accounts for 30% of colorectal cancer. The standard of treatment is surgical resection, which often is curative. For superior and middle-rectal involvement, low anterior resection (LAR) is the preferred procedure. For tumors involving the lower portion of the rectum, abdominoperineal resection (APR) or LAR are the options of treatment, depending on sphincter involvement. The main surgical objective is to achieve a R0 resection with an appropriated total mesorrectal excision, greater number of lymph nodes and negative distal and radial margins. These surgical parameters have been used as quality indicators and have prognostic implications in terms of overall and disease-free survival. Total mesorectal excision with preservation of hypogastric nerves has shown a reduction in rates of sexual and bladder dysfunction as well as lower local recurrence. At specialized centers such procedures are performed by minimal invasive surgery; however the number of meta-analysis is scarce.

Genomic integrity is threatened by multiple sources of DNA damage. DNA double-strand breaks (DSBs) are among the most dangerous types of DNA lesions and can be generated by endogenous or exogenous agents, but they can arise also during DNA replication. Sister chromatid recombination (SCR) is a key mechanism for the repair of DSBs generated during replication and it is fundamental for maintaining genomic stability. Proper repair relies on several factors, among which histone modifications play important roles in the response to DSBs. Here, we study the role of the histone H3K79 methyltransferase Dot1 in the repair by SCR of replication-dependent HO-induced DSBs, as a way to assess its function in homologous recombination. We show that Dot1, the Rad9 DNA damage checkpoint adaptor, and phosphorylation of histone H2A (gammaH2A) are required for efficient SCR. Moreover, we show that Dot1 and Rad9 promote DSB-induced loading of cohesin onto chromatin. We propose that recruitment of Rad9 to DSB sites mediated by gammaH2A and H3K79 methylation contributes to DSB repair via SCR by regulating cohesin binding to damage sites. Therefore, our results contribute to an understanding of how different chromatin modifications impinge on DNA repair mechanisms, which are fundamental for maintaining genomic stability.

Chromosome condensation and the global repression of gene transcription are features of mitosis in most eukaryotes. The logic behind this phenomenon is that chromosome condensation prevents the activity of RNA polymerases. In budding yeast, however, transcription was proposed to be continuous during mitosis. Here we show that Cdc14, a protein phosphatase required for nucleolar segregation and mitotic exit, inhibits transcription of yeast ribosomal genes (rDNA) during anaphase. The phosphatase activity of Cdc14 is required for RNA polymerase I (Pol I) inhibition in vitro and in vivo. Moreover Cdc14-dependent inhibition involves nucleolar exclusion of Pol I subunits. We demonstrate that transcription inhibition is necessary for complete chromosome disjunction, because ribosomal RNA (rRNA) transcripts block condensin binding to rDNA, and show that bypassing the role of Cdc14 in nucleolar segregation requires in vivo degradation of nascent transcripts. Our results show that transcription interferes with chromosome condensation, not the reverse. We conclude that budding yeast, like most eukaryotes, inhibit Pol I transcription before segregation as a prerequisite for chromosome condensation and faithful genome separation.

The structural maintenance of chromosome (SMC) proteins constitute the cores of three protein complexes involved in chromosome metabolism; cohesin, condensin and the Smc5-Smc6 complex. While the roles of cohesin and condensin in sister chromatid cohesion and chromosome condensation respectively have been described, the cellular function of Smc5-Smc6 is as yet not understood, consequently the less descriptive name. The complex is involved in a variety of DNA repair pathways. It contains activities reminiscent of those described for cohesin and condensin, as well as several DNA helicases and endonucleases. It is required for sister chromatid recombination, and smc5-smc6 mutants suffer from the accumulation of unscheduled recombination intermediates. The complex contains a SUMO-ligase and potentially an ubiquitin-ligase; thus Smc5-Smc6 might presently have a dull name, but it seems destined to be recognized as a key player in the maintenance of chromosome stability. In this review we summarize our present understanding of this enigmatic protein complex.

Objectives: The aim of this study was to characterize the different inhibitor-resistant TEM beta-lactamases, extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamases implicated in beta-lactam resistance in Proteus mirabilis, which has increased over recent years., Methods: From February 2000 to December 2005, 1423 clinical isolates of P. mirabilis were collected. The AmpC phenotype was checked by means of a double-disc synergy test using cloxacillin as an inhibitor of AmpC enzymes. The production of ESBL was assessed by the double-disc synergy method and by Etest ESBL. Analytical isoelectric focusing, determination of kinetic constants, conjugation, PCR and a sequencing strategy were used to characterize the enzymes. The possible relationships between isolates were analysed by PFGE., Results and Conclusions: Twenty-five of 1423 isolates were found to display intermediate or full resistance to co-amoxiclav, cefotaxime or ceftazidime. Seventeen isolates had reduced susceptibility to co-amoxiclav; of these, seven produced TEM-110, eight produced the new TEM-159, one the new TEM-160 and one TEM-1. Five isolates producing TEM-110, TEM-159 or TEM-160 enzymes shared the same PFGE profile. Three isolates produced an ESBL, CTX-M-1, CTX-M-32 and the new variant, VEB-4. Finally, five isolates with an AmpC phenotype produced CMY-2, two with the same PFGE profile. Our data emphasize the diversity of beta-lactamases found in this species.

Homologous recombination (HR) is crucial for maintaining genome integrity by repairing DNA double-strand breaks (DSBs) and rescuing collapsed replication forks. In contrast, uncontrolled HR can lead to chromosome translocations, loss of heterozygosity, and deletion of repetitive sequences. Controlled HR is particularly important for the preservation of repetitive sequences of the ribosomal gene (rDNA) cluster. Here we show that recombinational repair of a DSB in rDNA in Saccharomyces cerevisiae involves the transient relocalization of the lesion to associate with the recombination machinery at an extranucleolar site. The nucleolar exclusion of Rad52 recombination foci entails Mre11 and Smc5-Smc6 complexes and depends on Rad52 SUMO (small ubiquitin-related modifier) modification. Remarkably, mutations that abrogate these activities result in the formation of Rad52 foci within the nucleolus and cause rDNA hyperrecombination and the excision of extrachromosomal rDNA circles. Our study also suggests a key role of sumoylation for nucleolar dynamics, perhaps in the compartmentalization of nuclear activities.

Completion of DNA replication before mitosis is essential for genome stability and cell viability. Cellular controls called checkpoints act as surveillance mechanisms capable of detecting errors and blocking cell cycle progression to allow time for those errors to be corrected. An important question in the cell cycle field is whether eukaryotic cells possess mechanisms that monitor ongoing DNA replication and make sure that all chromosomes are fully replicated before entering mitosis, that is whether a replication-completion checkpoint exists. From recent studies with smc5-smc6 mutants it appears that yeast cells can enter anaphase without noticing that replication in the ribosomal DNA array was unfinished. smc5-smc6 mutants are proficient in all known cellular checkpoints, namely the S phase checkpoint, DNA-damage checkpoint, and spindle checkpoint, thus suggesting that none of these checkpoints can monitor the presence of unreplicated segments or the unhindered progression of forks in rDNA. Therefore, these results strongly suggest that normal yeast cells do not contain a DNA replication-completion checkpoint.

Homologous recombination (HR) is one of the key mechanisms responsible for the repair of DNA double-strand breaks (DSBs), including those that occur during DNA replication. Recent studies in yeast and mammals have uncovered that the SMC complexes cohesins and Smc5-Smc6 are recruited to induced DSBs, and play a role in the maintenance of genome stability by favouring SCR as the main recombinational DSB repair mechanism. These new results raise intriguing questions such as whether SMC proteins might play a functional role at collapsed replication forks, which may represent the main source of spontaneous recombinogenic damage. A deeper knowledge of the role of SMC proteins in DSB repair should contribute to a better understanding of chromosome dynamics and stability.

Nocardiosis has been believed to be caused by the members of the Nocardia asteroides complex and the Nocardia brasiliensis species. However, recent advances in genotypic identification have shown that the genus exhibits considerable taxonomic complexity and the phenotypic markers used in the past for its identification can be ambiguous. The aim of this study was to assess the species distribution of Nocardia isolates and to determine whether there are differences in pathogenicity or antimicrobial susceptibility between the different species identified. Nocardia isolates obtained over a 7 year period were retrospectively reviewed. The isolates were identified genotypically, their antibiotic susceptibility was tested and the clinical data of the 27 patients were retrieved. Eight different Nocardia species were identified: Nocardia farcinica (n=9), Nocardia abscessus (n=6), Nocardia cyriacigeorgica (n=6), Nocardia otitidiscaviarum (n=2), Nocardia nova (n=1), N. nova complex (n=1), Nocardia carnea (n=1) and Nocardia transvalensis complex (n=1). All species were susceptible to co-trimoxazole but different patterns of susceptibility to other agents were observed. All patients had active comorbidities at the time of infection. A total of 19 patients were immunosuppressed, due to human immunodeficiency virus infection, chronic corticosteroid therapy, immunosuppressive therapy or haematological malignancies. Six patients displayed a Charlson comorbidity index score above 4. Global mortality was 50 % while attributable mortality was 34.6 %. Patients infected with N. farcinica--the most resistant species--had the highest Charlson index score and the highest mortality rate. Accurate identification of the species and susceptibility testing of Nocardia isolates may play an important role in diagnosis and treatment.

Cellular checkpoints prevent mitosis in the presence of stalled replication forks. Whether checkpoints also ensure the completion of DNA replication before mitosis is unknown. Here, we show that in yeast smc5-smc6 mutants, which are related to cohesin and condensin, replication is delayed, most significantly at natural replication-impeding loci like the ribosomal DNA gene cluster. In the absence of Smc5-Smc6, chromosome nondisjunction occurs as a consequence of mitotic entry with unfinished replication despite intact checkpoint responses. Eliminating processes that obstruct replication fork progression restores the temporal uncoupling between replication and segregation in smc5-smc6 mutants. We propose that the completion of replication is not under the surveillance of known checkpoints.