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Rare examples of molecular, dinuclear CeIII and PrIII complexes with robust Ln-coordination are accessible by use of the tetraphenolate pTP as a supporting, chelating O-donor ligand platform, pTP = [2-(OC6H2R2-2,4)2CH-C6H4-1,4]4- that favours the higher formal oxidation states accessible to rare earths. Two classes of complexes have been made from the platforms; one metallacyclic 2 + 2 [Ln2(pTP)2] framework with a rigid, letterbox-shaped geometry and [Ln(aryloxide)4] core, and one more flexible [(LnX)2(pTP)] with one rare earth ion at either end of the platform. The LnIII letterbox complexes have two K+ counter-cations, one of which sits inside the letterbox, binding the two central arenes of the platform sufficiently strongly that it cannot be displaced by solvent molecules (THF and pyridine) or crown ethers. Oxidation of the CeIII lettterboxes is facile and forms the unusual neutral molecular (CeIV)2 letterbox in which the CeIV reduction potential is -1.83 V vs. Fc/Fc+. The electronic structure of the Ce(iii/iv) complexes was investigated using HERFD-XAS (high energy resolution fluorescence detection X-ray absorption spectroscopy).

Carlo Rostagno,1 Alessandro Cartei,2 Gaia Rubbieri,2 Alice Ceccofiglio,2 Roberto Civinini,3 Massimo Curcio,2 Gianluca Polidori,2 Alberto Boccaccini4 1Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy; 2Department of Internal and Post-Surgery Unit, AOU Careggi, Florence, Italy; 3Department of Orthopaedics, University of Florence, Florence, Italy; 4Department of Anaesthesia, AOU Careggi, Florence, ItalyCorrespondence: Carlo Rostagno, Department of Experimental and Clinical Medicine, University of Florence, Largo Brambilla 3, Florence, 50134, Italy, Tel +390557948545, Email carlo.rostagno@unifi.itBackground: In elderly patients with hip fracture, the prevalence of severe aortic stenosis (valve area < 1 cm2) is close to 5%. Few studies have evaluated the prognostic role of aortic stenosis in hip fracture surgery and none has considered the effects of the postoperative setting (intensive care unit vs general ward) on clinical outcome.Purpose: The aim of the present study was to evaluate the factors affecting mortality in patients with severe aortic stenosis undergoing surgery for hip fracture. We also evaluated whether postoperative monitoring in the intensive care unit may affect the prognosis in comparison to return to the general ward after surgery.Patients and Methods: All 2274 patients referred for hip fracture to our tertiary teaching hospital between January 1 2015 and December 31 2019 were screened for the presence of severe aortic stenosis, defined by an aortic valve area < 1.0 cm2.Results: The study included 66 patients (27 males, 39 females) with a mean±SD age of 85± 7 years. The average time between trauma and surgery was 2.6± 3 days. The mean aortic valve area was 0.74± 0.15 cm2. Seven patients died during hospitalization (10.4%). Diabetes, having two or more comorbidities, a low degree of autonomy, heart failure, history of coronary artery disease, atrial fibrillation, postoperative delirium and pulmonary hypertension were associated with poorer outcome. In logistic multivariate analysis, the number of diseases and values of pulmonary artery pressure were the only independent factors related to mortality. In hospital mortality (12 and 9%, respectively) and complication rates were not statistically different between patients referred to the intensive care unit for postoperative monitoring and patients returned to the general ward after surgery.Conclusion: In patients undergoing hip fracture surgery, severe aortic stenosis is associated with high hospital mortality, and two or more comorbidities and pulmonary hypertension are associated with a worse prognosis. The postoperative setting (intensive care unit or general ward) does not affect outcome.Keywords: aortic stenosis, prognosis, hip fracture, elderly

The DNA helicase Rrm3 promotes replication fork progression through > 1000 discrete genomic regions and represses the cDNA-mediated mobility of the Tyl retrotransposon. We explored the connection between DNA replication and Tyl retromobility by investigating the basis of increased retromobility in an rrm3 mutant. Even though Tyl cDNA levels are increased in the absence of RRM3, neither the level nor target-site specificity of cDNA integration was altered. Instead, cDNA was incorporated into the genome by a Rad52-dependent mechanism that did not involve gene conversion of genomic Tyl sequences. In rrm3 isolates, incorporated cDNA was often present in tandem arrays. Multimeric cDNA arrays probably arise during chromosomal break repair, since their appearance was strongly correlated with the formation of gross chromosomal rearrangements. Moreover Tyl multimers were invariantly located on rearranged chromosomes, when present. Overexpression of a cellular RNase H, which degrades RNA in an RNA:DNA hybrid, completely suppressed the increase in Tyl multimer formation in an rrm3 mutant. We propose that RNA:DNA hybrid regions within nascent retrotransposition events block replication in an rrm3 mutant, leading to chromosome breaks within Tyl sequences. Multiple extragenomic Tyl cDNA molecules are then used as donors in recombinational repair of the break before it is healed. DOI: 10.1534/genetics.109.104208

Tyl retrotransposons in Saccharomyces cerevisiae are activated by telomere erosion. Tyl-dependent reverse transcription of mRNA froin subtelomeric Y' repeats generates chimeric Y'-Tyl cDNA. Here, we show that Y'-Tyl cDNA is incorporated at eroding telomeres in the absence of telomerase. Telomeric incorporation of Y'-Tyl cDNA promotes genome rearrangements.

The yeast LTR retrotransposon Ty1 integrates preferentially into regions upstream of tRNA genes. The chromatin structure of transcriptionally active tRNA genes is known In be important for Ty1 integration, but specific chromatin factors that enhance integration at tRNA genes have not been identified. Here we report that the histone deacetylase, Hos2, and the Trithorax-group protein, Set3, both components of the Set3 complex (Set3C), enhance transposition of chromosomal Ty1 elements by promoting integration into the upstream region of tRNA genes. Deletion of HOS2 or SET3 reduced the mobility of a chromosomal Ty1 his3AI element about sevenfold. Despite the fact that Ty1 his3AI RNA, total Ty1 RNA, and total Ty1 cDNA levels were not reduced a hos2[DELTA] or set3[DELTA] mutants, transposition of endogenous Ty1 elements into the upstream regions of t[RNA.sup.Gly] genes was substantially decreased. Furthermore, when equivalent numbers of Ty1 HIS3 mobility events launched from a pGAL1:Ty1 his3AI plasmid were analyzed, only one-quarter to one-half as many were found upstream of t[RNA.sup.Glv] genes in a hos2[DELTA] or set3[DELTA] mutant than in a wild-type strain. Chromatin immunoprecipitation analysis revealed that Hos2 is physically associated with tRNA genes. Taken together, our results support the hypothesis that Hos2 and Set3 function at tRNA genes to promote Ty1 integration.

Most Ty1 retrotransposons in the genome of Saccharomyces cerevisiae are transpositionally competent but rarely transpose. We screened yeast mutagenized by insertion of the mTn3-lacZ/LEU2 transposon for mutations that result in elevated Ty1 cDNA-mediated mobility, which occurs by cDNA integration or recombination. Here, we describe the characterization of mtn3 insertions in 21 RTT (regulation of Ty1 transposition) genes that result in 5- to 111-fold increases in Ty1 mobilis. These 21 RTT genes are EST2, RRM3, NUT2, RAD57, RRD2, RAD50, SGS1, TEL1, SAE2, MED1, MRE11, SCH9, KAP122, and 8 previously uncharacterized genes. Disruption of RTT genes did not significantly increase Ty1 RNA levels but did enhance Ty1 cDNA levels, suggesting that most RTT gene products act at a step after mRNA accumulation but before cDNA integration. The rtt mutations had widely varying effects on integration of Ty1 at preferred target sites. Mutations in RTT101 and NUT2 dramatically stimulated Ty1 integration upstream of tRNA genes. In contrast, a mutation in RRM3 increased Ty1 mobility > 100-fold without increasing integration upstream of tRNA genes. The regulation of Ty1 transposition by components of fundamental pathways required for genome maintenance suggests that Ty1 and yeast have coevolved to link transpositional dormancy to the integrity of the genome.

rtt4-1 (regulator of Ty transposition) is a cellular mutation that permits a high level of spontaneous Tyl retrotransposition in Saccharomyces cerevisiae. The RTT4 gene is allelic with SSL2 (RAD25), which encodes a DNA helicase present in basal transcription (TFIIH) and nucleotide excision repair (NER) complexes. The ssl2-rtt (rtt4-1) mutation stimulates Tyl retrotransposition, but does not alter Tyl target site preferences, or increase cDNA or mitotic recombination. In addition to ssl2-rtt, the ssl2-dead and SSL2-1 mutations stimulate Tyl transposition without altering the level of Tyl RNA or proteins. However, the level of Tyl cDNA markedly increases in the ssl2 mutants. Like SSL2, certain mutations in another NER/TFIIH DNA helicase encoded by RAD3 stimulate Tyl transposition. Although Ss12p and Rad3p are required for NER, inhibition of Tyl transposition is independent of Ss12p and Rad3p NER functions. Our work suggests that NER/TFIIH subunits antagonize Tyl transposition posttranslationally by inhibiting reverse transcription or destabilizing Tyl cDNA.

We have developed a powerful new tool for the physical analysis of genomes called Ty1-mediated chromosomal fragmentation and have used the method to map 24 retrotransposon insertions into two different mouse-derived yeast artificial chromosomes (YACs). Expression of a plasmid-encoded GALI:Ty1 fusion element marked with the retrotransposition indicator gene, ade2AI, resulted in a high fraction of cells that sustained a single Ty1 insertion marked with ADE2. Strains in which Ty1ADE2 inserted into a YAC were identified by cosegregation of the ADE2 gene with the URA3-marked YAC. Ty1ADE2 elements also carried a site for the endonuclease I-DmoI, which we demonstrate is not present anywhere in the yeast genome. Consequently, I-DmoI cleaved a single chromosome or YAC at the unique site of Ty1ADE2 insertion, allowing rapid mapping of integration events. Our analyses showed that the frequency of Ty1ADE2 integration into YACs is equivalent to or higher than that expected based on random insertion. Remarkably, the 50-kb transcription unit of the mouse Steel locus was shown to be a highly significant hotspot for Ty1 integration. The accessibility of mammalian transcription units to Ty1 insertion stands in contrast to that of yeast transcription units.

Some introns in DNA have the ability to transfer themselves to other DNA sequences which then allow these sequences to self-initiate replication by causing parallel breaks in the DNA. The transfer of these group II introns was observed in yeast cells to be mediated by RNA through a reverse-transcription mechanism. Afterwards, one strand that forms from the break undergoes replication from cDNA that carries a copy of the intron.