The hypobranchial gland is a
glandular structure which is part of the anatomy of many
mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...
s, including several different families of
gastropods, and also many
protobranch bivalves. This gland produces mucus as well as biologically active compounds. The
cephalopod ink sac
An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods, all Coleoidea (squid, octopus and cuttlefish) which dwell ...
is a modified hypobranchial gland.
Anatomy and function
;Gastropods
The hypobranchial gland is found in many
sea snails, including those in the families
Haliotidae
''Haliotis'', common name abalone, is the only genus in the family Haliotidae.
This genus once contained six subgenera. These subgenera have become alternate representations of ''Haliotis''. The genus consists of small to very large, edible, ...
,
Buccinidae
The Buccinidae are a very large and diverse taxonomic family of large sea snails, often known as whelks or true whelks.Bouchet, P.; Gofas, S. (2010). Buccinidae. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) World Marine Mollusca database. Acc ...
,
Mitridae
Mitridae, known as mitre shells, are a taxonomic family of sea snails, widely distributed marine gastropod molluscs in the clade Mitroidea.MolluscaBase (2018). Mitridae Swainson, 1831. Accessed through: World Register of Marine Species at: ...
and
Costellariidae. It usually presents itself as a thickening of the tissue located in the roof of the animal's
mantle cavity
The mantle (also known by the Latin word pallium meaning mantle, robe or cloak, adjective pallial) is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of ...
. This is in association with parts of the aquatic mollusk anatomy that perform sediment consolidation in these organisms.
However, this gland is absent in all terrestrial gastropods except the Neritacea.
Its morphology, however, is variable between different groups of snails.
Glands with similar functions are present in the Nuculidae, Solenomyidae, Monia, Patellacea, and Loritcata.
In the Haliotidae, this gland has two lobes in the roof of the mantle cavity with the left larger than the right. It is deeply ridges and secretes mucus.
The purpose of the mucus is to trap, collect, and excrete sediment that collects as water flows over the gills of these organisms.
;Aculifera
In the aculifera the hypobranchial glands are referred to as "mucus tracts" and occupy a posterior position in the body.
Bacterial Community
In a study done on individuals from the species Dicathais orbita, a member of the Muricidae family, it was found that the bacterial community of the hypobranchial gland was highly specialized; The community was dominated by two genera: Mycoplasma and Vibrio, which are known to contain biosynthetic species.
These bacterial communities were compared to the foot of the individuals which had a larger variety of bacterial inhabitants.
Toxins
Some extracts from the hypobranchial gland have shown some toxic effects on human granulosa cells, cells inside the ovaries. These extracts can affect the hormone production of the reproductive system. As for all toxins, the effect is dependent on the dose and length of exposure to these extracts.
Human use
Tyrian Purple
There have been studies on some species within the family
Muricidae
Muricidae is a large and varied taxonomic family of small to large predatory sea snails, marine gastropod mollusks, commonly known as murex snails or rock snails. With about 1,600 living species, the Muricidae represent almost 10% of the Neoga ...
, because in those species this gland secretes the precursor to the historically important
natural dye
Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources—roots, berries, bark, leaves, and wood—and other biological sources such as fungi.
Archa ...
,
Tyrian purple
Tyrian purple ( grc, πορφύρα ''porphúra''; la, purpura), also known as Phoenician red, Phoenician purple, royal purple, imperial purple, or imperial dye, is a reddish-purple natural dye. The name Tyrian refers to Tyre, Lebanon. It i ...
.This dye has potential origins in history as early as 2000 BC in some areas of Europe and Asia. Due to the expensive process of dying fabrics with the hypobranchial grands of mollusks, Tyrian purple dyed fabrics were considered a symbol of wealth and royalty throughout much of history. It is synthesized from the dye precursor 6-6 dibromoindigo.
Medical Applications
There are some potential medical applications for the hypobranchial glands of mollusks ranging from anti-inflammatories, to anti-bacterials, to cancer.
Some of these uses were found by analyzing traditional medicine and therapeutic techniques from a variety of different cultures. In Ancient Greece, extracts from this gland were used as laxatives and diuretics with the potential for some side effects including increases in sweat and saliva productions.
Anti-bacterial Uses
* MeOH (Methanol) inhibited marine biofilm growth
* DCM (Dichloromethane) inhibited marine biofilm growth
* (CH₃)₂CO (Acetone) inhibited marine biofilm growth
Other extracts from the hemolymph of these mollusks have been shown to inhibit the growth of human pathogens.
Anti-inflammatory uses
* In lab cell lines and various animal models, extracts from the hypobranchial gland have shown a variety of muscle relaxing properties including the ability to act as a neuromuscular block, an anticonvulsant, a pain killer, and a sedative.
Cancer Treatments
* Chloroform extracts can inhibit the growth of lymphoma (cancer of the lung), reproductive system cancers, and colon cancer.
* A pigment in Tyrian purple, 6-dibromoindirubin, may slow the spread of a variety of cancers including lung, stomach, colon, abdominal, and leukaemia cancers.
* Extracts from the glands of Hexaplex trunculus showed possible adhesion inhibition of cervical and
glioblastoma
Glioblastoma, previously known as glioblastoma multiforme (GBM), is one of the most aggressive types of cancer that begin within the brain. Initially, signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality ...
cells, which can decrease the frequency of tumor formation.
References
Literature cited
* Fretter, V. & Graham, A. 1962. British Prosobranch Molluscs. 1st ed. London: The Ray Society, 755 pp.
* Westley, C., Lewis, M. C. and Benkendorff, K. 2010
''Histomorphology of the hypobranchial gland in Dicanthais orbita (Gmelin, 1791) (Neogastropoda: Muricidae)'' Journal of Molluscan Studies
The ''Journal of Molluscan Studies'' is the peer-reviewed scientific journal of the Malacological Society of London, covering research in malacology. 76(2): 186–195.
* ''The hypobranchial gland from the purple snail ''
Plicopurpura pansa'' (Gould, 1853) (Prosobranchia: Murididae)''.
Journal of Shellfish Research, August 1, 200
*Pontarotti, P. 2010. Evolutionary Biology: Concepts, Molecular and Morphological Evolutio
Springer, 363 pp.
{{Gastropod anatomy
Mollusc anatomy