Female gametogenesis and female gamete germination in the anisogamous green alga Codium fragile subsp. novae-zelandiae (Bryopsidophyceae, Chlorophyta).

MIRAVALLES, A. B; LEONARDI, P. I.; CÁCERES, E. J.

PHYCOLOGICAL RESEARCH (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. 60 p. 77 - 85

1322-0829

Female gametogenesis was studied in the dioecioussiphonous green alga Codium fragile subsp. novaezelandiae(J. Agardh) P. C. Silva using light and electronmicroscopy. Early during gametogenesis the protoplasmwas uniform; then it separated in portions, while fusiformchloroplasts and nuclei increased in numbers.Some features of the nuclear divisions were similar tothose of other Bryopsidophyceae. They were acentricand semi-open. Pairs of parallel electron-dense linesresembling synaptonemic complexes were observedin several prophase nuclei indicating meioses. Inmetaphase the nuclear envelope showed polar fenestraefrom which the spindle emerged. No spindle microtubulenucleating material was visible and chromosomekinetochores were evident. Mature female gameteswere pyriform with a hyaline anterior end from whichthe two flagella emerged. Mature gametes had a sphericalnucleus surrounded by a mitochondrion and numerousdiscoid chloroplasts. Female gametes germinatedparthenogenetically in culture and also inside gametangia,involving loss of flagella, rounding and lengtheningof cells, multiplication of chloroplasts with welldeveloped thylakoid systems, vacuolization and synthesisof a fibrillar cell wall.