Compositions and methods for inhibiting nematocyst discharge

Details Compositions and methods for inhibiting nematocyst discharge Compositions and methods for inhibiting nematocyst discharge

1997-10-08

2002-01-15

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S400000, C424S401000, C424S405000, C424S677000, C424S678000, C424S679000, C424S680000, C424S681000, C514S579000, C514S651000, C514S829000, C514S862000

Reexamination Certificate

active

06338837

ABSTRACT:

TECHNICAL FIELD
This invention is in the field of compositions which repel and prevent the stinging of marine organisms, such as jellyfish. In particular, compositions and methods for inhibiting the discharge of the stinging structure (nematocyst or polar capsule) are provided.
BACKGROUND
Swimmers and divers throughout the world are familiar with the stinging organisms of the oceans such as jellyfish, sea anemone and coral. Jellyfish stings, although seldom fatal, are a major public health problem. Lotan et al. (1992)
Marine Biology
112:237-242; Lotan et al. (1994)
Marine Ecology Progress Series
109:59-65. In the summer months, it is estimated that over 500,000 swimmers and divers in the Chesapeake Bay area and 200,00 persons in Florida are stung by jellyfish, mainly by “sea nettles,” the common name of
Chrysaora quinquecirrha
. Burnett et al. (1992)
MMJ
41(6):509-513. Similarly, between the months of March and August, one in four Florida bathers are stung and more than 10,000 persons require emergency medical treatment for pruritic eruptions caused by contact with jellyfish larvae known as “sea lice.” Tomchik et al. (1993)
JAMA
269(13):1669-1672.
The members of the phylum Cnidaria (e.g., jellyfish, sea anemone and coral) and the phylum Myxozoa are all equipped with stinging subcellular organelles, known as nematocysts, cnidocysts, or polar capsules. The nematocysts are located in specialized cells (nematocytes) and consist of a capsule containing a condensed tubule with potent toxins and threads. When nematocysts discharge, the tubule penetrates into its target organism and releases its toxins. The threads arrayed on the tubule enhance the anchoring and attachment of the nematocyst tubule to its target. Thus, nematocysts are involved in target recognition, toxin delivery, infection and attachment.
All members of the phyla Cnidaria and Myxozoa contain nematocysts of varying sizes, shapes and types. Mariscal, pp. 129-178, “Nematocysts” in COELENTERATE BIOLOGY: REVIEWS AND NEW PERSPECTIVES, eds. Muscatine and Lenhoff (Academic Press, New York, 1974). These different types of cnidocysts function in diverse biological roles including capture of prey, toxin delivery, recognition, attachment, adherence and infection. (see, e.g., Tardent (1995);
Bioessays
17(4):351-362; Lotan et al. (1995)
Nature
375:456; Lotan et al. (1996)
Expt'l Zool
. 275:444-451; Lotan etal., pp. 132-144
, “Toxicology and ecology and the Mediterranean jellyfish Rhopilema nomadica
” in BIOCHEMICAL ASPECTS OF MARINE PHARMACOLOGY, eds. Lazarovici et al. (Alaken, Inc., Fort Collins, Colo., 1996); Spaulding (1972)
Biol. Bull
. 143:440-453; Holstein and Tardent (1984)
Science
223:830-833 and Mariscal, supra. Thus, although best known for their stinging capabilities, nematocytes also play a key role in recognition, attachment and infection. For example, parasites from the phylum Myxozoa use nematocysts (polar capsules) to recognize and infect their hosts. El-Matbouli et al. (1995)
J. Fish Biol
. 46:919-935 and Yokoyama et al. (1995)
Diseases Aquatic Organ
. 21:7-11.
The main body of the nematocyte cell consists of a dense capsule, the nematocyst, within which is a high folded eversible tubule. Discharge (eversion) of this tubule is driven by the build up of a high internal hydrostatic pressure of approximately 150 atmospheres within the capsule. The eversion of the internally folded tubule occurs within 3 microseconds at accelerations of up to 40,000×g, one of the most rapid mechanical events in cell biology.
The nematocyte can be sub-divided into 3 morphological compartments with different functional entities: the capsule lumen and wall, the tubule and the sensory organelles. The capsule wall and lumen are the main components involved in developing the driving force for nematocyst discharge. The tension on the inner capsule wall during nematocyst discharge reaches up to 375 MPa. Holstein (1994)
Science
265:402-404. The strong capsule wall is highly permeable to water with a pore size of 600 Dalton. Within the resting nematocyst capsule, concentrations of up to 0.5 M of cations such as Ca
++
, Mg
++
or K
+
can be found. (see, e.g., Tardent, supra; Lubbock et al. (1981)
PNAS
78(6):3624-3628; Godknecht et al. (1988)
Marine Biology
100:83-92; Lubbock and Amos (1981)
Nature
290(5806):500-501; Weber (1989)
Int. J. Biochem
. 184:465-476; Hidaka (1993)
Biol. Bull
. 184:97-104 and Gerke (1991)
Hydrobiologia
216/217:661-669 for discussions of cations and nematocysts). The anionic counterparts are represented by poly-&ggr;-L-glutamatic acid (PGA) in varying degrees of polymerization. During nematocyst discharge, an extreme increase in internal capsule osmotic pressure occurs due to the influx of water. It has been suggested that the influx of water into the capsule is mediated by an internal release of the cations, such as Ca
++
in sea anemone or K
+
in hydra normally combined with PGA. This osmotic pressure is translated into hydrostatic pressure causing the eruption and then evagination of the tubule form the nematocyst capsule (discharge). After the nematocyst discharge the internal cation concentration of the capsule is dissolved into the surrounded fluids.
The second compartment of the nematocyst is a highly condensed eversible tubule. This tubule serves the main role in nematocyte biological function; namely, the interaction or delivery of substances from the cnidarian or myxozoan into its target. The tubule, which is 200-850 &mgr;m when elongated, is twisted more than a hundred times around its axis and is packed into the 3-10 &mgr;m diameter of the nematocyst. Godknecht & Tardent (1988)
Marine Biol
. 100:83-92. Hollow barbs, arrayed on the inner surface of the tubule, become everted during discharge and play an important role in the penetration and anchoring of the tubule into its prey. Toxins, contained on the outer surface before discharge, are delivered through the barbs after the nematocyst is anchored. Lotan et al. (1995), supra.
The sensory systems of the nematocyte are responsible for the control of nematocyst discharge. Discharge of nematocysts requires both chemical and mechanical stimulation of the sensory organelles. In the sea anemone
Aiptasia pallida
, two classes of chemical receptors have been identified. One type of receptor is triggered by N-acetylated sugars, while the second chemoreceptor is triggered by certain amino acids. Thorington et al. (1988)
Biol. Bull
. 174:163-171. The mechanical sensory system is dependent on activation of the chemoreceptors. These mechanoreceptors, however, can be adjusted by the organism, for instance, by tuning them to unique frequency signals emitted by a favored prey.
Certain fish diseases, including whirling disease, are caused by infection with an obligate parasite of the phylum myxozoan. (see e.g., for descriptions of myxozoan, Yokoyama et al. (1993)
Dis. Aquat. Org
. 17:223-228; Yokoyama et al. (1995)
Dis. Aquat. Org
. 21:7-11; Smothers et al. (1994)
Science
265:1719-172; and El-Matbouli et al. (1995)
J. Fish Biology
46:919-935). These parasites require two hosts, a fish and an aquatic annelid. The stages emerging from each host are infectious only for the other host, however, at each infectious stage, activated polar capsules (nematocyst) release a tubule that penetrates or adheres to the integument of the target. Host recognition is species-specific, indicating that nematocysts serve an important role in recognition of their host (El-Matbouli, supra).
In sum, nematocysts provide an effective method of delivering a substance deep into the target. Because nematocysts are able to penetrate their target so efficiently, it is difficult to remove them, or to treat after the toxin has penetrated. Conventionally, nematocysts stings have been treated with antidotes such as steroids, aluminum sulfate/surfactant and antihistamines. Tomchik, supra. For example, Wasuwat (1970)
Nature
225:758 describes how Thai fisherman use an extract made from the leaves of
Ipomoea pea-caprae
a

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