RESUMEN
BACKGROUND AND AIMS: Previous studies have suggested that velamen characteristics are useful as taxonomic markers in Orchidaceae. Members of tribe Cranichideae have been assigned to two velamen types constructed based on combinations of characters such as the presence of secondary cell-wall thickenings and pores. However, such characters have not been analysed on an individual basis in explicit cladistic analyses. METHODS: The micromorphology of roots of 26 species of Cranichideae was examined through scanning electron microscopy and light microscopy, scoring the variation and distribution of four characters: number of velamen cell layers, velamen cell-wall thickenings, presence and type of tilosomes, and supraendodermal spaces. The last three characters were analysed cladistically in combination with DNA sequence data of plastid trnK/matK and nuclear ribosomal internal transcribed spacer (ITS) regions and optimized on the resulting phylogenetic tree. KEY RESULTS: Thickenings of velamen cell walls group Prescottiinae with Spiranthinae, whereas tilosomes, documented here for the first time in Cranichideae, provide an unambiguous synapomorphy for subtribe Spiranthinae. Supraendodermal spaces occur mostly in species dwelling in seasonally dry habitats and appear to have evolved three times. CONCLUSIONS: Three of the four structural characters assessed are phylogenetically informative, marking monophyletic groups recovered in the combined molecular-morphological analysis. This study highlights the need for conducting character-based structural studies to overcome analytical shortcomings of the typological approach.
Asunto(s)
Orchidaceae/ultraestructura , Filogenia , Raíces de Plantas/ultraestructura , Pared Celular/ultraestructura , ADN de Plantas/química , ADN Espaciador Ribosómico/química , Orchidaceae/genéticaRESUMEN
A questionnaire was administered to 500 clinic patients and their replies about men and women physicians were analyzed. Ninety-six percent stated that the typical doctor is a man, and 78 percent expressed a preference for a male doctor. A significant number of patients said they would be unwilling to discuss certain subjects with a woman doctor or to follow her advice. Women physicians were considered less competent and less experienced than their male counterparts. Attitudes toward women doctors were correlated with patients' sex, age, ethnicity, occupation, and chief complaint. Most impressive statistically were the negative attitudes of Spanish-speaking patients and the positive responses of obstetrics and gynecology patients and black women patients. Patients who had previously consulted women physicians were more favorable toward them, suggesting that increased exposure may lead to reduced prejudice.