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sterol (n) - Any of a group of predominantly unsaturated solid alcohols of the steroid group, such as cholesterol and ergosterol, occurring in the fatty tissues of plants and animals.
As technology has
progressed, chemotaxonomic studies are more conceivable
and precise. In the 1970s, after experimentation since the
1940s, protocols and equipment were greatly enhanced, and
scientists coud isolate compounds that had represented one
tenth of one percent of a complex sterol mixture. Off the coast of Australia, in the Great Barrier Reef, sterol complements have helped to clarify different theories of taxonomy. In 1980, Dr. Patricia Bergquist delineated a new order, identified as Petrosida (class-Demospongiae). Previously, Petrosida had been conglomerated, under another name, within the order of Haplosclerida.
To test the theories,
Petrosida and Haplosclerida sponges were collected from
the Great Barrier Reef, New Zealand, Darwin, and Puerto
Rico. Thirty-eight porifera species were examined, and depths
ranged from five to one hundred meters. After an extensive,
elaborate, and accurate procss involving chloroform extraction,
column chromatography, gas chromatography, and other common
procedures, sterols were isolated. The error was calculated
to be approximately three to four percent. Of the Petrosida,
Xestospongia testudinaria contained five sterols
that were different among different samples. In addition,
there were several unconventional and nor sterols- but only
in a few samples. Throughout this page are diagrams of various
sterols that were isolated.
The authors of this page would like to thank Dr. Jane Fromont, Australia, for her contributions on this topic. She has made several other contributions to our page for which we are deeply indebted to her. |
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In
a more poriferan-related form, sterols are elements and
compounds in sponges that comprise their membranes. Within
the membranes, they control passage of materials. While
sterols are critical within all porifera, advanced organisms
such as vertebrates possess cholesterol, which complements
a developed nervous system. Since all porifera generate
and produce their own sterols for utilization within their
membranes, such is a simple characteristic to assist with
taxonomy. Additionally, species tend to maintain consistent
sterol complements despite diverse environments. Similarities
in sterol constituents indicate a chemotaxonomic relationship.
By seeking more accurate techniques to classify porifera,
sponge taxonomy is less theoretical and more factual. Once
the misconceptions of sponge taxonomy have been resolved,
more advanced studies may prevail. 
As a result, several new sterol compounds have been isolated
in the three previous decades. Studies have dissected compounds
to the atomic level, analyzing the structure of sterols
from molecular dimensions to the particulars of alkyloid
chains which accompany the compound. By applying sterol
investigation, the taxonomic tree of porifera may be altered.
Petrosida
was established upon the grounds that these species contained
specific sterol properties that differentiated them from
Haplosclerida species. Species within the Haplosclerida
order did not manifest such sterols. Therefore, the sterols
were an advanced characteristic of the Petrosida. To substantiate
such research, scientists required more in-depth research
pertaining to the sterol complements of the Petrosida order.
Studies needed to prove: a)that sterol complements were
the same throughout species, despite location and environment
and b)that Petrosida and Haplosclerida sterol complements
were diverse.
