World Congress of Malacology Antwerp ... - Unitas Malacologica

depth) near Chatham Rise, New Zealand, and the hot-vent inhabitant Ventsia tricarinata Warén &
Bouchet, 1993, (max. 2.5 mm) from the Lau Basin, Fiji (1800 m depth).
Ventsia tricarinata has papillate cephalic and epipodial tentacles, a single left monopectinate
ctenidium with skeletal roots and bursicles, a monotocard heart penetrated by the rectum, a left
papillate and a right excretory organ, a rhipidoglossate radula with one pair of radula cartilages, two
intestinal loops, a papillate oesophagus a hypoathroid nervous system, two statocysts with several
statoconia, a single left osphradium, a subradulary organ and one pair of ESO-tentacles. The sexes
are separated, the female genital systems consists of an ovary with big yolky eggs covered by a
vitellin layer, a simple urinogenital duct, and a separated receptaculum seminis.
Bathyxylophila excelsa differs as follows: The heart does not encircling the rectum, the oesophagus
lacks papillae. Due to insufficient fixation, many histological details could not be cleared up.
All anatomical data strongly suggest a position of both species inside the Vetigastropoda. However,
the combination of characters exclude both species from all currently defined subclades of the
Vetigastropoda. Until more data on possibly related forms are collected they remain as “incertae
sedis”.
Using molecular approaches to investigate the function of the hypobranchial gland of the
marine snail, Dicathais orbita
Laffy, Patrick W.; Benkendorff, Kirsten; Westley, Chantel; Abbott, Catherine A.
School of Biological Sciences, Flinders University, SA, USA
Email: patrick.laffy@flinders.edu.au; kirsten.benkendorff@flinders.edu.au;
chantel.westley@flinders.edu.au; cathy.abbott@flinders.edu.au.
The marine snail Dicathais orbita produces potent anti-cancer and antibacterial compounds as the
chemical precursors of the dye Tyrian purple within its hypobranchial gland (HBG). Furthermore,
choline esters have also been found in the HBG which may find clinical use due to their
neuromuscular blocking action. The identification of key enzymes expressed within the
hypobranchial gland may allow us to develop biosynthetic methods using recombinant techniques for
producing these pharmaceutically active compounds. It is known that there are three enzymes
involved in the formation of these compounds but the genes responsible have yet to be identified in
D. orbita or any marine mollusc. A more detailed investigation into HBG gene expression may also
indicate the biological processes and overall function of this organ in D. orbita.
Suppressive subtractive hybridization was performed to create a cDNA library from D. orbita HBG
RNA, containing genes that are differentially expressed in the HBG that are not expressed in D.
orbita mantle tissue. cDNA was then cloned and sequenced and a computer pipeline, created
specifically for processing this data, was used to identify coding gene sequences and their possible
functions. 400 unique sequences were obtained from the HBG of D. orbita. Of these sequences, 70
had their functions putatively identified with roles in electron transport, protein biosynthesis and
modification, acetylcholine metabolism and cell structure formation, as well as a partial arylsulfatase
sequence which may be involved in Tyrian purple production. These results indicate the HBG is a
biosynthetic organ. A gene involved in acetylcholine metabolism was also identified, suggesting a
cellular process for managing choline ester production exists within the HBG. Several sequences
were identified as using a ciliate protozoan coding system, and recent identification of protozoans
inhabiting the HBG suggests that suppressive subtraction has identified protozoan sequences, as well
as unique HBG transcripts.
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