Deep Sequencing Shows Multiple Oligouridylations Are Required for 3′ to 5′ Degradation of Histone mRNAs on Polyribosomes

Histone mRNAs are rapidly degraded when DNA replication is inhibited during S-phase with degradation initiating with oligouridylation of the stemloop at the 3′ end. We developed a customized RNA-Seq strategy to identify the 3′ termini of degradation intermediates of histone mRNAs. Using this strategy, we identified two types of oligouridylated degradation intermediates: RNAs ending at different sites of the 3′ side of the stemloop that resulted from initial degradation by 3′hExo and intermediates near the stop codon and within the coding region. Sequencing of polyribosomal histone mRNAs revealed that degradation initiates and proceeds 3′ to 5′ on translating mRNA and many intermediates are capped. Knockdown of the exosome-associated exonuclease Pml/Scl-100, but not the Dis3L2 exonuclease, slows histone mRNA degradation, consistent with 3′ to 5′ degradation by the exosome containing PM/Scl-100. Knockdown of No-go decay factors also slowed histone mRNA degradation, suggesting a role in removing ribosomes from partially degraded mRNAs

A Mitosis Block Links Active Cell Cycle with Human Epidermal Differentiation and Results in Endoreplication

How human self-renewal tissues co-ordinate proliferation with differentiation is unclear. Human epidermis undergoes continuous cell growth and differentiation and is permanently exposed to mutagenic hazard. Keratinocytes are thought to arrest cell growth and cell cycle prior to terminal differentiation. However, a growing body of evidence does not satisfy this model. For instance, it does not explain how skin maintains tissue structure in hyperproliferative benign lesions. We have developed and applied novel cell cycle techniques to human skin in situ and determined the dynamics of key cell cycle regulators of DNA replication or mitosis, such as cyclins E, A and B, or members of the anaphase promoting complex pathway: cdc14A, Ndc80/Hec1 and Aurora kinase B. The results show that actively cycling keratinocytes initiate terminal differentiation, arrest in mitosis, continue DNA replication in a special G2/M state, and become polyploid by mitotic slippage. They unambiguously demonstrate that cell cycle progression coexists with terminal differentiation, thus explaining how differentiating cells increase in size. Epidermal differentiating cells arrest in mitosis and a genotoxic-induced mitosis block rapidly pushes epidermal basal cells into differentiation and polyploidy. These observations unravel a novel mitosis-differentiation link that provides new insight into skin homeostasis and cancer. It might constitute a self-defence mechanism against oncogenic alterations such as Myc deregulation

Développement de la Filaire

Analyse morphologique et histologique du développement larvaire de la Filaire à microfilaires « dermiques » Monanema martini chez les larves hexapodes de Rhipicephalus sanguineus, R. turanicus et Hyalomma truncatum. Les stades infestants de la Filaire apparaissent au moment de la mue larve-nymphe du vecteur (11 jours à 26° C). Le développement s’effectue entièrement dans l’épiderme des tiques, comme celui, semble-t-il, des autres Monenama. Les Ixodidae se révèlent être les vecteurs majeurs des Filaires à microfilaires dermiques de la lignée Dipetalonema : Yatesia, Cherylia, Cercopithifilaria et Monanema

Imported diphyllobothriasis in Switzerland: molecular methods to define a clinical case of Diphyllobothrium infection as Diphyllobothrium dendriticum, August 2010

Following a first clinical case of infection by Diphyllobothrium dendriticum in Switzerland in 2006, we report a second case in the country. The species was identified by molecular methods. In the Swiss, French and Italian subalpine regions, human diphyllobothriasis has seen a comeback since the late 1980's, and Diphyllobothrium latum is usually considered the causative agent of the disease. In addition, several locally acquired and imported clinical infections due to allochthonous Diphyllobothrium species have been documented in the last years. Due to the colonisation potential of these parasites and their probably underestimated presence in the human population, there is a need for discriminating them at the medical laboratory level. Because the morphological characters are very similar among the different taxa, a correct identification requires the use of molecular methods. Molecular identification would improve diagnosis and help monitor the distribution of Diphyllobothrium species in Europe

Meningo-encephalo-myelo-radiculite a flavivirus: paresie bi-brachiale et insuffisance respiratoire. [Meningoencephalo-myeloradiculitis due to Flavivirus: bi-brachial paralysis and respiratory insufficiency]

3 patients developed rapid onset of fever and nuchal stiffness. Paresis of brachial muscles occurred within 4 days and all patients had respiratory failure that needed mechanical ventilation. At the peak of the disease there were bilateral asymmetrical severe atrophy of brachial, shoulder and neck muscles, cranial nerve pareses and absent or weak deep reflexes in the upper extremities. CSF analyses showed sterile lymphocytic pleocytosis. In 2 cases the patients suffered a tick bite in Switzerland and the third was probably bitten by an insect while opening a package received from Indonesia. Patients had rapid defervescence and serological tests were found to be highly positive for IgM and then IgG ELISA FSME (Fruhsommer-Meningoenzephalitis). The patients were ventilated for 2 to 5 weeks before a progressive improvement was seen. However, on follow-up at 12, 18 and 30 months respectively, proximal muscles were still atrophied and quite weak. Our cases underline that: (1) FSME-ELISA results may cross-react with the Japanese and Central European encephalitis virus species; (2) Flaviviruses do induce unusual and preferential long-term paralysis of the upper extremities simulating poliomyelitis; (3) in the 2 patients studied electrophysiologically, there were signs of axonal reinnervation not seen in lower motor neuron syndrome which were important for reinnervation to permit progressive, but late, motor improvement; (4) there is no evidence of extension of the endemic foci of tick-borne encephalitis in Switzerland

Combined screening for Chlamydia trachomatis and squamous intra-epithelial lesions using a single liquid-based cervical sample

BACKGROUND: Cervicitis is believed to alter cytological interpretation and could compromise a combined screening for Chlamydia trachomatis (CT) cervicitis and squamous intra-epithelial lesions (SIL). Liquid-based cytological methods have been shown to limit obscuring factors and permit the detection of infectious agents by DNA amplification techniques. The aim of this study was to evaluate a combined screening for SIL and CT cervicitis with a single liquid-based cervical sample. METHODS: Two cervical samples were obtained from each of 590 women considered at high risk for CT. The modified Ligase chain reaction (LCR) procedure for CT detection using specimens collected in the AutoCyte's preservative fluid was compared with the conventional Abbott LCx method using cervical swabs. We have also compared the percentage of inflammatory specimens and adequacy of cellular material in the populations of CT+ and CT- women. RESULTS: The results show total agreement for 588 of 590 cervical samples using the two LCR protocols (Kappa = 0.96; 95% confidence interval: 0.91-1.00). The quality of cervical cytology was not compromised by CT cervicitis. CONCLUSIONS: We demonstrated the feasibility of combined screening for CT and SIL with a single liquid-based cervical sampl

Deep Sequencing Shows Multiple Oligouridylations Are Required for 3′ to 5′ Degradation of Histone mRNAs on Polyribosomes

Histone mRNAs are rapidly degraded when DNA replication is inhibited during S-phase with degradation initiating with oligouridylation of the stemloop at the 3′ end. We developed a customized RNA-Seq strategy to identify the 3′ termini of degradation intermediates of histone mRNAs. Using this strategy, we identified two types of oligouridylated degradation intermediates: RNAs ending at different sites of the 3′ side of the stemloop that resulted from initial degradation by 3′hExo and intermediates near the stop codon and within the coding region. Sequencing of polyribosomal histone mRNAs revealed that degradation initiates and proceeds 3′ to 5′ on translating mRNA and many intermediates are capped. Knockdown of the exosome-associated exonuclease Pml/Scl-100, but not the Dis3L2 exonuclease, slows histone mRNA degradation, consistent with 3′ to 5′ degradation by the exosome containing PM/Scl-100. Knockdown of No-go decay factors also slowed histone mRNA degradation, suggesting a role in removing ribosomes from partially degraded mRNAs