Difference between revisions of "Volvox carteri"

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[[File:vc2.jpg|thumb|right|280px|'''Figure 2.''' (caption).]]
 
[[File:vc2.jpg|thumb|right|280px|'''Figure 2.''' (caption).]]
  
''Volvox carteri'' is a motile, multicellular eukaryotic species of green alga comprised of about 2,000 small somatic cells and 16 large reproductive cells (also known as gonidia), which interact in an extracellular matrix to form hollow, spherical colonies. <sup>[5][7]</sup> It can be found abundantly worldwide in freshwater ponds, lakes, and even some large puddles. The biflagellate characteristic of somatic cells allows ''V. carteri'' to move in its aqueous environment in order to adjust the amount of sunlight its photosynthetic cells receive.
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''Volvox carteri'' is a motile, multicellular eukaryotic species of green alga comprised of about 2,000 small somatic cells and 16 large reproductive cells (also known as gonidia), which interact in an extracellular matrix to form hollow, spherical colonies. <sup>[5][7]</sup> It can be found abundantly worldwide in freshwater ponds, lakes, and even some large puddles. The biflagellate characteristic of somatic cells allows ''V. carteri'' to move in its aqueous environment in order to adjust the amount of sunlight its photosynthetic cells receive <sup>[7]</sup>
  
 
Studies of green algae have provided a sufficient amount of information regarding the photosynthesis and biochemical processes of various plant species, proving ''Volvox aureus'' to be a valuable model system in ecological studies. <sup>[8]</sup>
 
Studies of green algae have provided a sufficient amount of information regarding the photosynthesis and biochemical processes of various plant species, proving ''Volvox aureus'' to be a valuable model system in ecological studies. <sup>[8]</sup>

Revision as of 19:30, 15 April 2018

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Classification

Figure 1. Volvox carteri (?).

Higher Order Taxa

Domain: Eukaryota

Kingdom: Viridiplantae

Phylum: Chlorophyta

Class: Chlorophyceae

Order: Chlamydomonadales

Family: Volvocaceae

Species

Volvox carteri

NCBI: [1]

Description and Significance

Figure 2. (caption).

Volvox carteri is a motile, multicellular eukaryotic species of green alga comprised of about 2,000 small somatic cells and 16 large reproductive cells (also known as gonidia), which interact in an extracellular matrix to form hollow, spherical colonies. [5][7] It can be found abundantly worldwide in freshwater ponds, lakes, and even some large puddles. The biflagellate characteristic of somatic cells allows V. carteri to move in its aqueous environment in order to adjust the amount of sunlight its photosynthetic cells receive [7]

Studies of green algae have provided a sufficient amount of information regarding the photosynthesis and biochemical processes of various plant species, proving Volvox aureus to be a valuable model system in ecological studies. [8]

Genome Structure

The Volvox carteri genome was first sequenced in 2010.[6] It had generated interest as a model system to examine the evolution of multicellularity and genomic complexity associated with such a phenomenon. The number of chromosomes that composes the nuclear genome of V. carteri is unestablished; some sources indicate the identification of up to 19 distinct linkage groups, while others find just 14.[5][6] A number of genome characteristics have been defined, however. The nuclear genome is 138 Mbp long and 18% coding, with a GC content of 56%.[5]

A number of papers investigating the evolution of complexity and multicellularity compare the V. carteri genome to a related member of the Volvocine algae family, Chlamydomonas reinhardtii. Relative to the other species in the family, these two organisms are as far apart evolutionarily as possible; C. reinhardtii is simpler and unicellular. Though sequencing both of their genomes has given us insights into their evolutionary history, interest in an examination of genomes of intermediate species has been demonstrated.[6]

Even so, an examination of the genetic differences between V. carteri and C. reinhardtii provided new insights into the development of multicellularity. Though it had long been assumed that multicellularity required the development of a substantially different genetic background, comparisons between these two organisms revealed a strikingly similar genome. In many of the genes identified as required in the evolution of multicellularity, similar genes were present in C. reinhardtii. Both have a similar number of genes and their domain content is also similar.[6]

Cell Structure, Metabolism and Life Cycle

(structure of somatic/germ cells)

Figure 3. Life cycle of Volvox carteri (?).

A notable structural feature of Volvox carteri is the formation of microscopic cytoplasmic bridges between somatic cells of the colonies, originating from incomplete cell division during cytokinesis. [1] These connections, which can only be seen by using electron microscopy, allows the movement of small organelles such as mitochondria between cells. As the cells of a colony move further apart, the strands become stretched and therefore smaller, allowing only ribosomes and endoplasmic reticulum to be exchanged among cells. [3] The ability to transport information between cells allows V. carteri to synchronize its movements and reproductive actions. [1][3] This unique quality of cells interacting with one another in order to benefit the parent colony is similar to the actions of a multicellular organism. [1]

(how Volvox gains energy and what it produces)

(life cycle/reproduction) [9][10]

Ecology

Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

References

[1] Kirk, D.L., Birchem, R., and King, N. “The Extracellular Matrix of Volvox: A Comparative Study and Proposed System of Nomenclature.” Journal of Cell Sciences. 1986. Volume 80. p. 207-231.

[2] Lotha, G., Petruzzello, M., Promeet, D., and Rimsa, C. "Volvox: Genus of Green Algae." Encyclopedia Britannica. 2016.

[3] Schiedlmeier, B., Schmitt, R., Müller, W., Kirk, M.M., Gruber, H., Mages, W., and Kirk, D.L. "Nuclear transformation of Volvox carteri." Proceedings of the National Academy of Science. 1994. Volume 91. p. 5080-5084.

[4] Cornish, A.J., Green, R., Gärtner, K., Mason, S., Hegg, E.L. "Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri." PloS one. 2015. Volume 10. p. 1-15.

[5] Prochnik, Simon E et al. “Genomic Analysis of Organismal Complexity in the Multicellular Green Alga Volvox Carteri.” Science (New York, N.Y.) 329.5988 (2010): 223–6. Web. 14 Apr. 2018.

[6] Umen, James G, and Bradley J S C Olson. “Genomics of Volvocine Algae.” Advances in botanical research 64 (2012): 185–243. Web. 14 Apr. 2018.

[7] Choi, G., Przybylska, M., and Straus, D. "Three abundant germ line-specific transcripts in Volvox carteri encode photosynthetic proteins." Current Genetics. 1996. Volume 30. p. 347-355.

[8] Moseley, K.R. and Thompson, G.A. "Lipid Composition and Metabolism of Volvox carteri." Plant Physiology. 1980. Volume 65. p. 260-265.

[9] Nedelcu, A.M., Marcu, O., and Michod, R.E. "Sex as a response to oxidative stress: a twofold increase in cellular reactive oxygen species activates sex genes." Proceedings of the Biological Sciences. 2004. Volume 271. p. 1591-1596.

[10] Green, K.J. and Kirk, D.L. "Cleavage Patterns, Cell Lineages, and Development of a Cytoplasmic Bridge System in Volvox Embryos." Journal of Cell Biology. 1981. Volume 91. p. 743-755.

Authors

Page authored by Madison Fiegl and JD French, students of Prof. Jay Lennon at Indiana University.