INVESTIGADORES
PARODI Elisa Rosalia
artículos
Título:
Fine-structure of the zoosporogénesis and early gametophyte development in Cladophora surera (Cladophorales, Chlorophyta).
Autor/es:
CACERES, EDUARDO J; E. R. PARODI
Revista:
JOURNAL OF PHYCOLOGY
Editorial:
Wiley-Blackwell
Referencias:
Año: 1998 p. 1 - 1
ISSN:
0022-3646
Resumen:
The fine-structure of zoosporogenesis, zoospore germination and early gametophyte development in Cladophora surera Parodi et Cáceres, were studied.  Zoosporogenesis started with simultaneous meiosis in all nuclei of apical initial cells.  The resulting haploid nuclei duplicated in turn by successive centric, closed mitosis.  Then, each initial cell was divided into two short zoosporangia.  Numerous vacuoles appeared around each sporic nucleus.  The delimitation of uninucleate zoosporocytes occurred by cytokinetic furrows produced by the coalescence of tiny, clear vesicles, without microtubules.  Final shape of the the zoospore resulted from gradual expulsion of vacuoles from the cell body.  Mature biflagellate zoospores exhibited a conspicuous apical papilla containing fine granular globules, the basal apparatus and a microtubular “umbrella” formed by numerous cortical microtubules which ran backwards the length of the cell body.  The chloroplast showed a conspicuous eyespot.  The zoosporangial wall disorganized at the pore through which the zoospores were liberated.  Zoospores settled on a substrate by their anterior papilla secreting an adhesive.  Germination involved retraction  of the apical papilla, loss of the “umbrella” microtubules and eyespot, and the lateral absorption of the entire flagellar apparatus, i.e. basal apparatus plus axoneme, into the cytoplasm.  Early gametophyte development involved the synthesis of a thin, young cell wall, the development of outer peripheral vacuoles, the appearance of the marginal reticulate chloroplast  and the formation of the first central vacuoles derived from abundant endoplasmic reticulum.  Close to the plasmalemma ran longitudinally-oriented cortical microtubules.  Eventually the germling developed an achlorophylic, elongated rhizoidal portion.   Key index words: Cladophora surera; Cladophoraceae, Cladophorales; Chlorophyta; fine-structure; Ulvophyceae; ultrastructure; zoospores; zoosporogenesis; zoospore germination.