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Genomic architecture at the Incontinentia Pigmenti locus favours de novo pathological alleles through different mechanisms.

IKBKG/NEMO gene mutations cause an X-linked, dominant neuroectodermal disorder named Incontinentia Pigmenti (IP). Located at Xq28, IKBKG/NEMO has a unique genomic organization, as it is part of a segmental duplication or low copy repeat (LCR1-LCR2, >99% identical) containing the gene and its pseudogene copy (IKBKGP). In the opposite direction and outside LCR1, IKBKG/NEMO partially overlaps G6PD, whose mutations cause a common X-linked human enzymopathy. The two LCRs in the IKBKG/NEMO locus are able to recombine through non-allelic homologous recombination producing either a pathological recurr…

Genetic transformation of mouse embryos by microinjection of purified DNA.

A recombinant plasmid composed of segments of herpes simplex virus and simian virus 40 viral DNA inserted into the bacterial plasmid pBR322 was microinjected into pronuclei of fertilized mouse oocytes. The embryos were implanted in the oviducts of pseudopregnant females and allowed to develop to term. DNA from newborn mice was evaluated by the Southern blotting technique for the presence of DNA homologous to the injected plasmid. Two of 78 mice in one series of injections showed clear homology, though the injected sequences had been rearranged. Band intensities from the two positive mice were

PrimeStack editors enable efficient and site-specific integration of large multigene cargos in plants.

Precise, site-specific integration of large DNA sequences into plant genomes is a long-standing goal of crop biotechnology and synthetic biology, yet remains constrained by random insertion, inefficient homologous recombination, and gene targeting. Here, we present PrimeStack, a DSB-independent platform that integrates PE with the unidirectional large serine integrase Bxb1, leveraging evolved variants for enhanced activity, to achieve the programmable insertion of multigene, multikilobase cargos at predefined genomic safe harbors (GSH) in rice (Oryza sativa). Optimized prime editors first inst…

A Tel1-Rad9 axis links DNA double-strand break end-tethering to repair pathway choice.

In eukaryotes, DNA double-strand breaks (DSBs) activate Tel1/ATM- and Mec1/ATR-dependent checkpoint signaling and can be repaired by homologous recombination (HR), which requires DNA end resection, typically initiated by the MRX/MRN complex. In budding yeast, Sae2/CtIP promotes MRX-dependent end processing, limits Tel1-Rad53 signaling, and contributes to DSB end-tethering. Here, we identify a Tel1 FAT-domain variant, Tel1-400, that increases the DNA damage resistance of sae2Δ cells by suppressing their DSB end-tethering defect through Rad9 phosphorylation-dependent oligomerization. Tel1-400 ac…

SYCP2 recruits HORMAD2 to chromosome axes for unsynapsed chromatin silencing and synapsis surveillance in meiosis.

Faithful chromosome segregation during meiosis requires accurate recombination and synapsis of homologous chromosomes. These processes are monitored in mammals by checkpoints involving the meiotic HORMA-domain proteins HORMAD1 and HORMAD2, which bind unsynapsed chromosome axes and promote activation of the DNA damage-response kinase ATR independently of DNA double-strand breaks (DSBs). However, the in vivo mechanism for axial HORMAD1 and HORMAD2 recruitment and its relevance to checkpoint signaling remain unclear, although the chromosome-axis component SYCP2 has been proposed to contain a cand

Emerging mechanisms and roles of meiotic crossover repression at centromeres.

Crossover events during recombination in meiosis are essential for generating genetic diversity as well as crucial to allow accurate chromosomal segregation between homologous chromosomes. Spatial control for the distribution of crossover events along the chromosomes is largely a tightly regulated process and involves many facets such as interference, repression as well as assurance, to make sure that not too many or too few crossovers are generated. Repression of crossover events at the centromeres is a highly conserved process across all species tested. Failure to inhibit such recombination

Выяснить оптимальные сроки дублирования для стабильности репортеров.

Флавивирусы, передающиеся с помощью москито, вызывают широко распространенные болезни во всем мире. В целях обеспечения более совершенных молекулярных инструментов для изучения лекарственных экранов и патогенеза мы сообщаем о новом подходе к производству стабильных флавивирусов, пропитанных нанолуком, включая серотипы денге 1-4, японский энцефалит, вирус желтой лихорадки, вирус Западного Нила и вирус Зика. Поскольку ген репортера часто проектируется в генной области Капсида, последовательность капсида должна быть дублирована для фланга гена репортера; такое копирование капсида имеет важное зна

Совпадение в аннотации оригинала
ABSTRACT Mosquito-transmitted flaviviruses cause widespread disease across the world. To provide better molecular tools for drug screens and … zing reporter flaviviruses has been to shorten or modify the duplicated capsid sequence to minimize homologous recombination. No study has examined the effects of capsid duplication length on reporter virus stability. Here we report an optimal length to stabilize reporter flaviviruses. These viruses were stable after ten rounds of cell culture passaging, and in the case o …

The rem mutations in the ATP-binding groove of the Rad3/XPD helicase lead to Xeroderma pigmentosum-Cockayne syndrome-like phenotypes.

The eukaryotic TFIIH complex is involved in Nucleotide Excision Repair and transcription initiation. We analyzed three yeast mutations of the Rad3/XPD helicase of TFIIH known as rem (recombination and mutation phenotypes). We found that, in these mutants, incomplete NER reactions lead to replication fork breaking and the subsequent engagement of the homologous recombination machinery to restore them. Nevertheless, the penetrance varies among mutants, giving rise to a phenotype gradient. Interestingly, the mutations analyzed reside at the ATP-binding groove of Rad3 and in vivo experiments revea…

Genomic basis of a polyagglutinating isolate of Neisseria meningitidis.

Containment strategies for outbreaks of invasive Neisseria meningitidis disease are informed by serogroup assays that characterize the polys … 6917 belongs to serogroup B. These results suggest that a capsule-switching event occurred based on homologous recombination at or around the capsule locus of M16917. Detailed analysis of this locus uncovered the locations of recombination breakpoints in the M16917 genome sequence, which led to the introduction of an ∼2-kb serogroup B sequence cassette into the serogroup …

A deletion of FGFR2 creating a chimeric IIIb/IIIc exon in a child with Apert syndrome.

BACKGROUND: Signalling by fibroblast growth factor receptor type 2 (FGFR2) normally involves a tissue-specific alternative splice choice between two exons (IIIb and IIIc), which generates two receptor isoforms (FGFR2b and FGFR2c respectively) with differing repertoires of FGF-binding specificity. Here we describe a unique chimeric IIIb/c exon in a patient with Apert syndrome, generated by a non-allelic homologous recombination event. CASE PRESENTATION: We present a child with Apert syndrome in whom routine genetic testing had excluded the FGFR2 missense mutations commonly associated with this…

SNCA locus duplication carriers: from genetics to Parkinson disease phenotypes.

Genomic multiplication of the alpha-synuclein gene (SNCA) locus is one cause of familial Parkinson disease (PD). We performed detailed genom … We sequenced the break junction and confirmed the involvement of L1PA2 and L1PA4 in a non-allelic, homologous recombination. An analysis of mRNA levels in immortalized lymphoblastoid cells and peripheral blood mononuclear cells showed SNCA overexpression in subjects with the duplication, as well as overexpression of 13 other genes highlighting the usefulness of such cell …

Chromosomal instability in enterohaemorrhagic Escherichia coli O157:H7: impact on adherence, tellurite resistance and colony phenotype.

Tellurite (Tel) resistant enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is a global pathogen. In strain EDL933 Tel resistance (Tel(R) ) is encoded by duplicate ter cluster in O islands (OI) 43 and 48, which also harbour iha, encoding the adhesin and siderophore receptor Iha. We identified five EHEC O157:H7 strains that differentiate into large (L) colonies and small (S) colonies with high and low Tel minimal inhibitory concentrations (MICs) respectively. S colonies (Tel-MICs ≤ 4 µg ml⁻¹) sustained large internal deletions within the Tel(R) OIs via homologous recombination between IS eleme…

Alternative recombination pathways in UV-irradiated XP variant cells.

XP variant (XP-V) cells lack the damage-specific polymerase eta and exhibit prolonged replication arrest after UV irradiation due to impaired bypass of UV photoproducts. To analyse the outcome of the arrested replication forks, homologous recombination (HR, Rad51 events) and fork breakage (Rad50 events) were assayed by immunofluorescent detection of foci-positive cells. Within 1 h of irradiation, XP-V cells showed more Rad51-positive cells than normal cells, while neither cell type showed an increase in Rad50 foci. Beyond 1 h, the frequency of Rad51-positive cells reached similar levels in bot…

Identification and characterization of novel mutations of the major Fanconi anemia gene FANCA in the Japanese population.

Fanconi anemia (FA) is a rare autosomal recessive disorder of hematopoiesis, with at least 11 complementation groups. FANCA, a gene for grou … function relationship of FANCA. Specifically, our data suggest that diverse mechanisms including nonhomologous recombination as well as Alu-mediated homologous recombination are involved in the generation of large deletions in FANCA.

Complete nucleotide sequence and evolutionary significance of a chromosomally encoded naphthalene-degradation lower pathway from Pseudomonas stutzeri AN10.

Pseudomonas stutzeri strain AN10 is a naphthalene-degrading strain whose dissimilatory genes are chromosomally encoded. We sequenced the entire naphthalene-degradation lower pathway of P. stutzeri AN10, this being, together with the upper-pathway reported previously (Bosch R. et al., 1999a. Gene 236, 149-157) the first complete DNA sequence for an entire naphthalene-catabolic pathway. Eleven open reading frames were identified. The nahGTHINLOMKJ genes encode enzymes for the metabolism of salicylate to pyruvate and acetyl-CoA, and nahR encodes the NahR regulatory protein. Our findings suggest t

Low-copy repeats mediate the common 3-Mb deletion in patients with velo-cardio-facial syndrome.

Velo-cardio-facial syndrome (VCFS) is the most common microdeletion syndrome in humans. It occurs with an estimated frequency of 1 in 4, 000 … e repeats are virtually identical in the 200-kb region, suggesting that the deletion is mediated by homologous recombination. Examination of two three-generation families showed that meiotic intrachromosomal recombination mediated the deletion.

CD40-deficient mice generated by recombination-activating gene-2-deficient blastocyst complementation.

To study the role of B-cell antigen CD40 in immune responses, mouse embryonic stem (ES) cells in which both copies of the gene encoding CD40 had been disrupted by homologous recombination were injected in RAG-2 (recombination-activating gene-2)-deficient blastocysts to generate chimeras in which all mature lymphocytes are derived from the CD40-deficient ES cells. T- and B-cell number and phenotype were normal in the CD40-/- chimeras. However, B cells failed to proliferate and undergo isotype switching in vitro in response to soluble CD40 ligand (sCD40L) with interleukin 4 (IL-4) but responded …

Targeted gene disruption in Epstein-Barr virus.

We report the development of a method that should allow the insertion of a selective marker into any region of the Epstein-Barr virus (EBV) genome of strain B95-8 through homologous recombination with plasmids. In this method, EBV recombinants are isolated as G418-resistant, immortalized B-cell clones or as G418-resistant, latently infected subclones of Burkitt lymphoma cell lines. The presence of the productive replication origin of EBV, oriLyt, on the plasmid was found to increase the number of observed recombinant viruses by approximately 100-fold; this stimulation was observed when oriLyt …

Genome-wide mapping of Cas9-induced sister chromatid exchange across single and over 200 genomic sites in human cells.

CRISPR/Cas9-induced DNA double-strand breaks (DSBs) are widely used for genome engineering, yet their capacity to provoke sister chromatid e … SCEs and at SCE junctions, indicating that Cas9-induced SCE does not universally reflect error-free homologous recombination. Disruption of LIG3, LIG4, XRCC1, and XRCC4 at Cas9 cut sites did not measurably alter SCE frequency, consistent with delayed functional loss following editing. Together, these findings identify Cas9-induced DSBs as potent local triggers of SCE and …

Auto-sumoylation of UBC9 coordinates meiotic prophase and protects ovarian reserves.

The small ubiquitin-like modifier SUMO regulates key events of meiosis, including pairing and crossing over between homologous chromosomes. Auto-sumoylation of the SUMO E2-conjugating enzyme UBC9 at lysine 14 alters its substrate selectivity in vitro, but the role of this modification in vivo is unknown. Here, we show that UBC9-K14 auto-sumoylation helps coordinate meiotic prophase and is important for maintenance of the ovarian reserve. Ubc9K14R/K14R knock-in mice show a variety of defects in meiotic prophase I, including altered assembly of DNA strand-exchange complexes, delayed and defectiv