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Pedinellia
The axodines are a group of unicellular stramenopiles that includes silicoflagellate and rhizochromulinid algae, actinomonad heterotrophic flagellates and actinophryid heliozoa. Alternative classifications treat the dictyochophytes as heterokont algae, or as Chrysophyceae. Other overlapping taxonomic concepts include the Actinochrysophyceae, Actinochrysea or Dictyochophyceae ''sensu lato''. The grouping was proposed on the basis of ultrastructural similarities, and is consistent with subsequent molecular comparisons. The Axodine grouping was unusual in breaking with the traditions of botanical and protozoological taxonomy to include the actinophryid heliozoa as part of the lineage that also contained the pedinellid algae along with colorless relatives such as ''Actinomonas'', Pteridomonas, and ''Ciliophrys''; the axodines further included the silicoflagellates, and Rhizochromulinales. This followed a growing consensus that the actinophryid heliozoa were not related to other type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinophryida
The actinophryids are an order of heliozoa, a polyphyletic array of stramenopiles, having a close relationship with pedinellids and ''Ciliophrys''. They are common in fresh water and occasionally found in marine and soil habitats. Actinophryids are unicellular and roughly spherical in shape, with many axopodia that radiate outward from the cell body. Axopodia are a type of pseudopodia that are supported by hundreds of microtubules arranged in interlocking spirals and forming a needle-like internal structure or axoneme. Small granules, extrusomes, that lie under the membrane of the body and axopodia capture flagellates, ciliates and small metazoa that make contact with the arms. Description Actinophryids are largely aquatic protozoa with a spherical cell body and many needle-like axopodia. They resemble the shape of a sun due to this structure, which is the inspiration for their common name: heliozoa, or "sun-animalcules". Their bodies, without arms, range in size from a few tens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algae Classes
Algae ( , ; : alga ) are any of a large and diverse group of photosynthetic, eukaryotic organisms. The name is an informal term for a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as '' Chlorella'', '' Prototheca'' and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to in length. Most are aquatic and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the '' Charophyta'', a division of green algae which includes, for example, '' Spirogyra'' and stoneworts. Algae that are carried by water are plankton, specifically phytoplankton. Algae constitute a polyphyletic group since they do not include a common ancestor, and although their plastids seem to have a single orig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or more distinct types of flagella - tinsel or "decorated", and whiplash, in various combinations. *Tinsellated (straminipilous) flagella have lateral filaments known as mastigonemes perpendicular to their main axis, which allow for more surface area, and disturbance of the medium, giving them the property of a rudder, that is, used for steering. *Whiplash flagella are straight, to power the zoospore through its medium. Also, the "default" zoospore only has the propelling, whiplash flagella. Both tinsel and whiplash flagella beat in a sinusoidal wave pattern, but when both are present, the tinsel beats in the opposite direction of the whiplash, to give two axes of control of motility. Morphological types In eukaryotes, the four main type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long stands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicoflagellate
Dictyochales (Silicoflagellates, or Dictyochophyceae ''sensu stricto'') are a small group of unicellular heterokont algae, found in marine environments. Characteristics In one stage of their life cycle, they produce a siliceous skeleton, composed of a network of bars and spikes arranged to form an internal basket. These form a small component of marine sediments, and are known as microfossils from as far back as the early Cretaceous. Classification The algae in the Dictyochophyceae have been previously classified in the Chrysophyceae. There is one living genus, ''Dictyocha'', with two commonly recognised species. There are also several extinct genera, but their classification is difficult, since skeletons may show diverse forms within each living species. ''Dictyocha'' has one golden-brown chloroplast and a long flagellum extended into a wing-like shape. The skeleton-bearing stage is uninucleate, with many microtubule-supported projections, and there are also uninucleate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
