Imaging spectrum of acute invasive fungal rhino-orbital-cerebral sinusitis in COVID-19 patients: A case series and a review of literature.

BACKGROUND: The incidence of devastating opportunistic coinfections in patients with COVID-19 infection, their imaging features and their morbidity and mortality consequences need to be unraveled. METHODS: This is a case series presenting the radiologic features and clinical presentation of acute invasive fungal rhino-orbital-cerebral sinusitis (AIFS) in eight hospitalized patients with confirmed COVID-19 infection. RESULTS: Our patient cohort presented with symptoms of the invasive fungal disease within 12-35 days from their initial presentation with COVID-19 infection. The cross-sectional imaging features of AIFS associated with COVID-19 infection do not differ from those reported in the literature for AIFS associated with other risk factors, yet our patients had features of aggressive late-stage forms with high morbidity and mortality rate. CONCLUSION: AIFS is a possible encounter in patients with COVID-19 patients and radiologists should be familiar with its imaging features.

Dmc1 of Schizosaccharomyces pombe plays a role in meiotic recombination.

We report here a Schizosaccharomyces pombe gene (dmc1(+)) that resembles budding yeast DMC1 in the region immediately upstream of the rad24(+) gene. We showed by northern and Southern blot analysis that dmc1(+) and rad24(+) are co-transcribed as a bicistronic mRNA of 2.8 kb with meiotic specificity, whereas rad24(+) itself is constitutively transcribed as a 1.0-kb mRNA species during meiosis. Induction of the bicistronic transcript is under the control of a meiosis-specific transcription factor, Ste11. Disruption of both dmc1(+) and rad24(+) had no effect on mitosis or spore formation, and dmc1Delta cells displayed no change in sensitivity to UV or gamma irradiation relative to the wild type. Tetrad analysis indicated that Dmc1 is involved in meiotic recombination. Analysis of gene conversion frequencies using single and double mutants of dmc1 and rhp51 indicated that both Dmc1 and Rhp51 function in meiotic gene conversion. These observations, together with a high level of sequence identity, indicate that the dmc1(+) gene of S. POMBE: is a structural homolog of budding yeast DMC1, sharing both similar and distinct functions in meiosis.

Replication factor C3 of Schizosaccharomyces pombe, a small subunit of replication factor C complex, plays a role in both replication and damage checkpoints.

We report here the isolation and functional analysis of the rfc3(+) gene of Schizosaccharomyces pombe, which encodes the third subunit of replication factor C (RFC3). Because the rfc3(+) gene was essential for growth, we isolated temperature-sensitive mutants. One of the mutants, rfc3-1, showed aberrant mitosis with fragmented or unevenly separated chromosomes at the restrictive temperature. In this mutant protein, arginine 216 was replaced by tryptophan. Pulsed-field gel electrophoresis suggested that rfc3-1 cells had defects in DNA replication. rfc3-1 cells were sensitive to hydroxyurea, methanesulfonate (MMS), and gamma and UV irradiation even at the permissive temperature, and the viabilities after these treatments were decreased. Using cells synchronized in early G2 by centrifugal elutriation, we found that the replication checkpoint triggered by hydroxyurea and the DNA damage checkpoint caused by MMS and gamma irradiation were impaired in rfc3-1 cells. Association of Rfc3 and Rad17 in vivo and a significant reduction of the phosphorylated form of Chk1 in rfc3-1 cells after treatments with MMS and gamma or UV irradiation suggested that the checkpoint signal emitted by Rfc3 is linked to the downstream checkpoint machinery via Rad17 and Chk1. From these results, we conclude that rfc3(+) is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor.