No priming, just fighting-endophytic yeast attenuates the defense response and the stress induced by Dutch elm disease in Ulmus minor Mill.

One century after the first report of Dutch elm disease (DED), there is still no practical solution for this problem threatening European and American elms (Ulmus spp.). The long breeding cycles needed to select resistant genotypes and the lack of efficient treatments keep disease incidence at high levels. In this work, the expression of defense-related genes to the causal agent of DED, Ophiostoma novo-ulmi Brasier, was analyzed in in vitro clonal plantlets from two DED-resistant and two DED-susceptible Ulmus minor Mill. trees. In addition, the effect of the inoculation of an endophytic pink-pigmented yeast (Cystobasidium sp.) on the plant's defense system was tested both individually and in combination with O. novo-ulmi. The multifactorial nature of the resistance to DED was confirmed, as no common molecular response was found in the two resistant genotypes. However, the in vitro experimental system allowed discrimination of the susceptible from the resistant genotypes, showing higher levels of oxidative damage and phenolic compounds in the susceptible genotypes after pathogen inoculation. Inoculation of the endophyte before O. novo-ulmi attenuated the plant molecular response induced by the pathogen and moderated oxidative stress levels. Niche competition, endophyte-pathogen antagonism and molecular crosstalk between the host and the endophyte are discussed as possible mechanisms of stress reduction. In sum, our results confirm the complex and heterogeneous nature of DED resistance mechanisms and highlight the possibility of using certain endophytic yeasts as biological tools to improve tree resilience against biotic stress.

Reproducibility study of cervical cytopathology in Mexico: a need for regulation and professional accreditation.

Due to the high rate of false negative results in diagnosis of cervical cytopathology, in many countries its practice has been transformed through the application of several interventions aimed at medical regulation to improve diagnostic accuracy. Diagnostic reproducibility of gynecological cytopathology was evaluated in a series of 20 cytology specimens [Papanicolaou (Pap)] and 20 cervical biopsy. (CB) studies in different clinical stages, during 1994. The observation unit consisted of 30 pathologists who observed 2 groups of 20 Pap and 20 CB specimens. The standard was a cytopathologist certified by the Pathological Anatomy Council of Mexico. Intraclass reproducibility in gynecological cytopathology is low in Mexico. In a group analysis, concordance increased as clinical status of the cervical lesion increased. For moderate dysplasia, concordance in Pap was kappa = 0.04, compared to 0.23 in CB. Concordance of diagnosis of invasive cancer was 0.29 for Pap and 0.64 for CB. Using weighted kappa at the individual level for all possible diagnoses, concordance varied from 0.29 to 0.59 for Pap, and 0.42 to 0.65 for CB. The problem of reproducibility in cervical cytopathology in Mexico emphasizes the need for continuing education, uniform diagnostic criteria, and the advantages of a single operational classification-possibly the Bethesda System-since current classification systems are obsolete.

[Diagnostic concordance in gynecologic cytology]. / Concordancia diagnóstica en citología ginecológica.

OBJECTIVE: To evaluate the diagnostic agreement in Papanicolaou of pathologists and cytotechnologists using kappa values for concordancy. METHODS: The diagnostic variation was estimated in 20 gynecological cytology (Pap) specimens by 30 pathologists and 7 cytotechnologists attending the XXXVII Congress of the Mexican Association of Pathologists in 1994. RESULTS: The best concordancy versus an expert was in tumoral diathesis (pathologists' kappa = 0.36; cytotechnologists' kappa = 0.35) and kollocytos (pathologists' kappa = 0.55; cytotechnologists' kappa = 0.36). The least concordancy was observed in anisonucleosis (pathologists' kappa = 0.11; cytotechnologists' kappa = 0.02), nuclear hyperchromasia (pathologists' and cytotechnologists' kappa = 0.11) and dyskeratosis (pathologists' kappa = 0.11; cytotechnologists' kappa = 0.16). The kappa values for cervical neoplasia showed poor agreement, and in invasive cervical cancer it was 0.30. CONCLUSIONS: There was a low concordancy of Pap diagnosis in the study. It is convenient to try to improve the concordancy of cytologic diagnosis in Mexico. One strategy could be the use of a uniform diagnostic criteria and the adoption of a single nomenclature.