LIFE CYCLE OF NASSULA ORNATA AND NASSULA ELEGANS: ARE THESE SPECIES VALID?
نویسندگان
چکیده
منابع مشابه
Fine structure and function of the cytopharyngeal basket in the ciliate Nassula.
The fine structure of the cytopharyngeal basket is described in detail. A circular palisade of cytopharyngeal rods is encircled at certain levels by a sheath and two annuli; crest-shaped structures project outwards from the basket. The rods, crests and sheath are largely composed of cytoplasmic microtubules of approximate diameter 240 A. One of the annuli is mostly composed of densely staining ...
متن کاملChanges in nuclear structure during binary fission in the ciliate Nassula.
During binary fission intranuclear spindles are formed in the three micronuclei and in the macronucleus. The nuclear envelopes remain intact throughout nuclear division. At one stage all the nuclei are linked together by the formation of membrane bridges in continuity with the outer membranes of their envelopes. Three types of filamentous structure have been distinguished in the spindles: micro...
متن کاملDevelopment and deployment of cilia, basal bodies, and other microtubular organelles in the cortex of the ciliate Nassula.
The basal bodies contain more internal structures than those described for other organisms. For example, they possess 2 different and separate cartwheel structures. In cilia the 2 central tubules terminate proximally in a different fashion. Three types of cilia have been distinguished. Each type possesses a different array of rootlet fibres. During binary fision one type develops 1 h before all...
متن کاملHow many named species are valid?
Estimates of biodiversity in both living and fossil groups depend on raw counts of currently recognized named species, but many of these names eventually will prove to be synonyms or otherwise invalid. This difficult bias can be resolved with a simple "flux ratio" equation that compares historical rates of invalidation and revalidation. Flux ratio analysis of a taxonomic data set of unrivalled ...
متن کاملEndocytosis and streaming of highly gelated cytoplasm alongside rows of arm-bearing microtubules in the ciliate Nassula.
The microtubular cytopharyngeal basket acts as a jet engine when Nassula ingests filaments of blue-green algae. Prolonged and highly directed cytoplasmic streaming forms the main mechanical basis for propulsion of algal filaments through the basket. Cytoplasm surrounding such filaments streams at the same rate as that at which filaments travel through the basket's interior. This cytoplasm appea...
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ژورنال
عنوان ژورنال: The Biological Bulletin
سال: 1926
ISSN: 0006-3185,1939-8697
DOI: 10.2307/1536940