Cutinsomes of Malus Mill. (Rosaceae) leaf and pericarp: genesis, localization, and transport.

New data were obtained on specific bionanostructures, cutinsomes, which are involved in the formation of cuticles on the surface of leaf blades and pericarp of Malus domestica Borkh (Malus Mill., Rosaceae)introduced to the mountains at the altitudes of 1200 and 1700 m above sea level. Cutinsomes, which are electron-dense structures of spherical shape, have been identified by transmission electron microscopy. It was demonstrated that plastids can be involved in the synthesis of their constituent nanocomponents. The greatest number of nanoparticles was observed in the granal thylakoid lumen of the chloroplasts in palisade mesophyll cells and pericarp hypodermal cells. The transmembrane transport of cutinsomes into the cell wall cuticle proper by exocytosis has been visualized for the first time. The plasma membrane is directly involved in the excretion of nanostructures from the cell. Nanoparticles of cutinsomes in the form of necklace-like formations line up in a chain near cell walls, merge into larger conglomerates and are loaded into plasmalemma invaginations, and then, in membrane packing, they move into the cuticle, which covers both outer and inner cell walls of external tissues. The original materials obtained by us supplement the ideas about the non-enzymatic synthesis of cuticle components available in the literature and expand the cell compartment geography involved in this process.

Ultrastructural features of Mimulus aurantiacus (Scrophulariaceae) pollen tubes in vivo

The aim of this study is to give information on ultrastructure of in vivo pollen tubes of Mimulus aurantiacus which were collected from the Botanical Garden of the University of California at Berkeley. Materials were prepared according to electron microscopy methods and examined under Zeiss electron microscope. Four zones were examined in the pollen tubes of Mimulus aurantiacus. APICAL ZONE: Mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, dictyosomes and secretory vesicles were observed. SUBAPICAL ZONE: This area contained abundant rough endoplasmic reticulum and occasionally some smooth endoplasmic reticulum. The polysomes, mitochondria, proplastids that contain starch, small vacuoles and a few lipid bodies were detected. NUCLEAR ZONE: Both generative and vegetative cell nuclei lie in this zone. The vegetative cell nucleus was large and long. Rough endoplasmic reticulum, mitochondria, ribosomes, dictyosomes, and amyloplasts that are rich of starch were observed. VACUOLATION AND PLUG FORMATION ZONE: Cytoplasm of the tubes was full of large vacuoles. Few organelles such as mitochondria, dictyosome and rough endoplasmic reticulum were detected along their periphery.

O objetivo deste estudo é informar sobre a ultraestrutura de tubos de pólen de Mimulus aurantiacus in vivo coletados no "Botanical Garden" da Universidade da Califórnia em Berkeley. O material foi preparado de acordo com os métodos de microscopia eletrônica e examinado em microscópio eletrônico Zeiss. Quatro zonas dos tubos de pólen de Mimulus aurantiacus foram examinadas. ZONA APICAL: foram observados mitocôndrias, retículo endoplasmático liso; retículo endoplasmático rugoso, dictiossomos e vesículas secretoras. ZONA SUBAPICAL: esta área continha retículo endoplasmático rugoso em abundância e, ocasionalmente, algum retículo endoplasmático liso. Foram detectados polissomos, mitocôndrias, proplastídeos que contêm amido, pequenos vacúolos e alguns corpos lipídicos. ZONA NUCLEAR: nesta área, existem tanto núcleos de células geradoras como vegetativas. O núcleo de célula vegetativa é grande e longo. Foram observados retículo endoplasmático rugoso, mitocôndria, ribossomos, dictiossomos e amiloplastos ricos em amido. ZONA DE VACUOLIZAÇÃO E DE FORMAÇÃO DE "PLUG": o citoplasma dos tubos estava cheio de grandes vacúolos. Algumas organelas como mitocôndria, dictiossomo e retículo endoplasmático rugoso foram detectadas em toda a periferia desta área.

Taxonomía y filogenética de Rhinosporidium seeberi, un patógeno para el ser humano y los animales: revisión crítica / The taxonomy and phylogenetics of the human and animal pathogen Rhinosporidium seeberi: a critical review

Rhinosporidum seeberi es el agente etiológico de la rinosporidiosis, una enfermedad de las membranas mucosas y, con menos frecuencia, de la piel y otros tejidos. Debido a que se resiste a crecer en los medios de cultivo desde hace más de 100 años, la identidad taxonómica de R. seeberi ha sido motivo de controversia. Tres nuevas hipótesis en una larga lista de puntos de vista similares han sido introducidas: 1) la cianobacteria Microcystis es el agente etiológico de la rinosporidiosis, 2) R. seeberi es un patógeno eucariota en los Mesomycetozoa, y 3) R. seeberi es un hongo. La literatura revisada sobre los estudios realizados con microscopia electrónica, los datos histopatológico y, más recientemente, los datos de varios estudios moleculares, apoyan fuertemente la idea de que R. seeberi es un patógeno eucariota, pero no un hongo. La semejanza morfológica propuesta por algunos de que R. seeberi es similar a los miembros de los géneros Microcystis (bacteria), Synchytrium y Colletotrichum (hongos) es meramente hipotética y no tiene el rigor científico necesario para validar el sistema propuesto. Un aspecto fundamental en contra de la teoría procariota es la presencia de núcleos descrita por numerosos autores y que actualizamos en esta revisión. Además, las características ultra-estructurales de los géneros Microcystis y Synchytrium y de sus ciclos celulares no han sido encontradas en la fase parasitaria de R. seeberi. La amplificación por PCR de una secuencia del rADN 16S típica de las cianobacterias en muestras de casos de rinosporidiosis, aunque interesante, será considerada en esta revisión como una anomalía debido a la contaminación con el medio ambiente (Microcystis) o tal vez como una adquisición endosimbiótica de plastidios a partir de cianobacterias ancestrales. Así pues, aunque R. seeberi podría poseer ADN procariota, esto no demuestra necesariamente que R. seeberi sea una cianobacteria. La clasificación de R. seeberi dentro de los hongos es insostenible. El aislamiento de un hongo, los análisis de ADN realizados, y la ausencia de controles apropiados son los problemas más importantes de esta teoría. Más estudios serán necesarios para validar la adquisición de plastidios procariotas en R. seeberi, y otros temas que requieren un cuidadoso escrutinio(AU)

Rhinosporidum seeberi is the etiologic agent of rhinosporidiosis, a disease of mucous membranes and infrequent of the skin and other tissues of humans and animals. Because it resists culture, for more than 100 years true taxonomic identity of R. seeberi has been controversial. Three hypotheses in a long list of related views have been recently introduced: 1) a prokaryote cyanobacterium in the genus Microcystis is the etiologic agent of rhinosporidiosis, 2) R. seeberi is a eukaryote pathogen in the Mesomycetozoa and 3) R. seeberi is a fungus. The reviewed literature on the electron microscopic, the histopathological and more recently the data from several molecular studies strongly support the view that R. seeberi is a eukaryote pathogen, but not a fungus. The suggested morphological resemblance of R. seeberi with the genera Microcystis (bacteria), Synchytrium and Colletotrichum (fungi) by different teams is merely hypothetical and lacked the scientific rigor needed to validate the proposed systems. A fundamental aspect against the prokaryote theory is the presence of nuclei reported by numerous authors and updated in this review. Moreover, Microcystis's and Synchytrium's ultra-structural and key cell cycle traits cannot be found in R. seeberi parasitic phase. The PCR amplification of a cyanobacteria 16S rDNA sequence from cases of rhinosporidiosis, while intriguing, will be viewed here as an anomaly due to contamination with environmental Microcystis or perhaps as an endosymbiotic acquisition of plastids from cyanobacteria ancestors. Thus, even if R. seeberi possesses prokaryote DNA, this does not prove that R. seeberi is a cyanobacterium. The placement of R. seeberi within the fungi is scientifically untenable. The isolation and the DNA analysis performed in a fungal strain, and the lack of appropriate controls are the main problems of this claim. Further studies are needed to validate R. seeberi's acquisition of prokaryote plastids and other issues that still need careful scrutiny(AU)

Fine structural study of the red seaweed Gymnogongrus torulosus (Phyllophoraceae, Rhodophyta)

The present study analyzed several characters of the red seaweed Gymnogongrus torulosus, such as cellular structure of the thallus, cuticle, pit plug and cell wall ultrastructure, and morphology of some organelles like plastids, Golgi bodies and mitochondria. Also, anomalous chloroplasts with thylakoid disorganization were found in medullary cells. The significance of this thylakoid disposition is still unclear. This is one of the first studies focused on the fine structure of a red alga recorded in Argentina.