Strongylocentrotus_purpuratus_California

''Strongylocentrotus purpuratus'', the purple sea urchin, lives along the eastern edge of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

extending from Ensenada,

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, to

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. This sea urchin species is deep purple in color, and lives in lower inter-tidal and nearshore sub-tidal communities. Its eggs are orange when secreted in water. January, February, and March function as the typical active reproductive months for the species. Sexual maturity is reached around two years. It normally grows to a diameter of about 10 cm (4 inches) and may live as long as 70 years.

Role in biomedical research

The initial discovery of three distinct eukaryotic DNA-dependent RNA polymerases was made using ''S. purpuratus'' as a model organism. While embryonic development is still a major part of the utilization of the sea urchin, studies on urchin's position as an evolutionary marvel have become increasingly frequent. Orthologs to human diseases have led scientists to investigate potential therapeutic uses for the sequences found in ''Strongylocentrotus purpuratus''. For instance, in 2012, scientists at the

University of St Andrews (Aien aristeuein) , motto_lang = grc , mottoeng = Ever to ExcelorEver to be the Best , established = , type = Public research university Ancient university , endowment ...

began investigating the "2A" viral region in the ''S. purpuratus'' genome which may be useful for Alzheimer's disease and cancer research. The study identified a sequence that can return cells to a 'stem-cell' like state, allowing for better treatment options. The species has also been a candidate in longevity studies, particularly because of its ability to regenerate damaged or aging tissue. Another study comparing 'young' vs. 'old' suggested that even in species with varying lifespans, the 'regenerative potential' was upheld in older specimens as they suffered no significant disadvantages compared to younger ones.

Genome

The genome of the purple sea urchin was completely sequenced and annotated in 2006 by teams of scientists from over 70 institutions including the

Kerckhoff Marine Laboratory The William G. Kerckhoffbr>Marine Laboratory'' is owned and operated by the California Institute of Technology (Caltech). It is located 101 Dahlia Street, in the Corona del Mar district of Newport Beach, in Orange County, California. History T ...

at the

California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

as well as the

Human Genome Sequencing Center The Baylor College of Medicine Human Genome Sequencing Center (BCM-HGSC) was established by Richard Gibbs (biologist), Richard A. Gibbs in 1996 when Baylor College of Medicine was chosen as one of six worldwide sites to complete the final phase of t ...

at the

Baylor College of Medicine Baylor College of Medicine (BCM) is a medical school and research center in Houston, Texas, within the Texas Medical Center, the world's largest medical center. BCM is composed of four academic components: the School of Medicine, the Graduate S ...

. A new improved version of the purple sea urchin, ''Strongylocentrotus purpuratus'' v5.0 is now available o
Echinobase
''S. purpuratus'' is one of several biomedical research model organisms in cell and developmental biology. The sea urchin is the first animal with a sequenced genome that (1) is a free-living, motile marine

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

; (2) has a bilaterally organized embryo but a radial adult body plan; (3) has the

endoskeleton An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue. Overview An endoskeleton is a skeleton that is on the ...

and water vascular system found only in echinoderms; and (4) has a nonadaptive

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

that is unique in the enormous complexity of its receptor repertoire. The sea urchin genome is estimated to encode about 23,500 genes. The ''S. purpuratus'' has 353 protein kinases, containing members of 97% of human kinase subfamilies. Many of these genes were previously thought to be vertebrate innovations or were only known from groups outside the deuterostomes. The team sequencing the species concluded that some genes are not

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

specific as thought previously, while other genes still were found in the urchin but not the chordate. The genome is largely non-redundant, making it very comparable to vertebrates, but without the complexity. For example, 200 to 700 chemosensory genes were found that lacked introns, a feature typical of vertebrates. Thus the sea urchin genome provides a comparison to our own and those of other deuterostomes, the larger group to which both

echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...

s and humans belong. Sea urchins are also the closest living relative to chordates. Using the strictest measure, the purple sea urchin and humans share 7,700 genes. Many of these genes are involved in sensing the environment, a fact surprising for an animal lacking a head structure. The sea urchin also has a chemica
'defensome'
that reacts when stress is sensed to eliminate potentially toxic chemicals. ''S. purpuratus'''s immune systems contains innate pathogen receptors like

Toll-like receptor Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. They are single-pass membrane-spanning receptors usually expressed on sentinel cells such as macrophages and dendritic cells, that recognize ...

s and genes that encode for LRR . There were genes identified for

Biomineralization Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often to harden or stiffen existing tissues. Such tissues are called mineralized tissues. It is an extremely widespread phenomenon; ...

that were not counterparts of the typical human vertebrate variet
SCCPs
and encode for

transmembrane A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequent ...

proteins like

P16 p16 (also known as p16INK4a, cyclin-dependent kinase inhibitor 2A, CDKN2A, multiple tumor suppressor 1 and numerous other synonyms), is a protein that slows cell division by slowing the progression of the cell cycle from the G1 phase to the S p ...

. Many

orthologs Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a sp ...

exist for genes associated with human diseases, such as

Reelin Reelin, encoded by the ''RELN'' gene, is a large secreted extracellular matrix glycoprotein that helps regulate processes of neuronal migration and positioning in the developing brain by controlling cell–cell interactions. Besides this impor ...

(from Norman-Roberts lissencephaly syndrome) and many cytoskeletal proteins of the Usher syndrome network like usherin and VLGR1. Increasing carbon dioxide concentrations affect the

epigenome An epigenome consists of a record of the chemical changes to the DNA and histone proteins of an organism; these changes can be passed down to an organism's offspring via transgenerational stranded epigenetic inheritance. Changes to the epigenome ...

, gene expression, and

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...

of the purple sea urchin. Carbon dioxide concentration also reduces the size of its larvae, which indicates that fitness of the larvae could be negatively impacted.

Ecology

The purple sea urchin, along with

sea otters The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the smalle ...

and abalones, is a prominent member of the

kelp forest Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on Ea ...

community. The purple sea urchin also plays a key role in the disappearance of kelp forests that is currently occurring due to climate change.

Use as food

Sea urchins like the purple sea urchin have been used for food by the

indigenous peoples of California The indigenous peoples of California (known as Native Californians) are the indigenous inhabitants who have lived or currently live in the geographic area within the current boundaries of California before and after the arrival of Europeans. ...

, who ate the yellow egg mass raw. In California, the peak gonad growth season (and therefore peak of edibility) is September–October. Early in the season, the gonads are still growing and the yield will be smaller. From November onwards the gonads are developed, however harvesting stress can induce spawning, decreasing quality.

References

External links