Volvox africanus

Volvox africanus sample under a microscope at 400X magnification. Image credit: The University of Texas at Austin. https://utex.org/products/utex-lb-1890

Volvox africanus samples under a transmission electron microscope. The samples are in the asexual spheroid form. Image credit: Nozaki, Mahakham, Heman, Matsuzaki, and Kawachi (2022). https://www.researchgate.net/publication/358009972_Morphology_mating_system_and_taxonomy_of_Volvox_africanus_Volvocaceae_Chlorophyceae_from_Thailand

Computer animated reconstruction of a Volvox. Image credit: https://botnam.com/volvox-case-study-guide/

Classification

Eukarya; Chlorophyta; Chlorophyceae; Chlamydomonadales; Volvocaceae

Species

Volvox africanus

NCBI: [1]

Description and Significance

Volvox africanus is a photosynthetic, multicellular eukaryotic microbe that lives in clusters. Volvox species exist as many cell colonies within a gelatinous barrier. They contain anywhere from several hundred to 6,000 cells within their gelatin bubble. In fact, the largest clusters are barely visible with the naked eye.

Volvox is a freshwater algal genus that was first discovered by Anton von Leeuwenhook in the 1700s. They have fascinating reproductive cycles consisting of both sexual and asexual reproduction.

Genome Structure

Volvox africanus has a haploid, linear genome, with between 129-142 megabases (mb). The National Center for Biotechnology Information (NCBI) holds two full genomic sequences of this species. One sequence discovered about 13,455 protein coding genes, 129 contigs, and that 53% of the genome is comprised of GC nucleotides. The other sequence resulted in different data. It matched the first with the genome containing 53% of GC nucleotides, however, it found 12,742 protein coding genes and 448 contigs.

Cell Structure, Metabolism, and Life Cycle

Volvox shape is complex to describe due to the vast number of cells within their gelatinous barrier. Essentially, one Volvox is a bunch of cocci unicellular organisms living within a spheritical gel-like substance. Each of cocci cells, either somatic or germ cells, have two flagella. Other organelles include; chloroplasts, eyespots, and vacuoles. The somatic cells move their flagellum in tandem for fast, coordinated directional movements. Their eyespot further compliments this because it directs the somatic cell's flagellar movements to the location of light. As a result, the Volvox chloroplasts receive a plethora of photosynthesis opportunities.

Photosynthesis is the primary energy source of the Volvox.

It reproduces both asexually and sexually.

Ecology and Pathogenesis

Live in freshwaters sources, and like most algal species, rely on photosynthesis for nutrients and energy. As a result, they are valuable for consuming carbon dioxide and releasing oxygen for aerobic organisms. Somatic cells contain one chloroplast each.

Typically found in South Africa, other southern african countries, and south Asia.

All discovered Volvox species are non-pathogenic.

References

https://en.wikipedia.org/wiki/Volvox https://utex.org/products/utex-lb-1890 https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=51714 https://eol.org/pages/901574 https://www.algaebase.org/search/species/detail/?species_id=C60a996d47989b5be https://www.researchgate.net/figure/Transmission-electron-microscopy-of-asexual-spheroids-of-Volvox-africanus-GS-West_fig3_358009972 https://www.britannica.com/science/green-algae

Authors

Page authored by Hayden Hull, student of Professor Bradley Tolar at UNC Wilmington.