Sharp-nosed pit viper

''Deinagkistrodon'' is a monotypic genus created for the venomous pit viper species, ''D. acutus'', which is endemic to Southeast Asia. No subspecies are currently recognized.

Description

''Deinagkistrodon acutus'' is light brown or greyish brown dorsally, with a series of dark brown lateral triangles on each side. The two pointed tops of the two opposite triangles meet each other at the mid-line, forming a series of about 20 light brown, squarish blotches on the back. A row of large black spots extends along each side near the belly. The top and upper sides of the head are uniformly black, with a black streak from the eye to the angle of the mouth. ''D. acutus'' is yellowish ventrally, spotted with dark brown. The young are much lighter than the adults with essentially the same pattern. The head is large, triangular, with an upturned snout. The body is very stout. The tail is short, ending in a compressed, pointed slightly curved cornified scale. The top of the head is covered with nine large shields. The dorsal scales are strongly and tubercularly keeled. The subcaudals are mostly in pairs, some of the anterior ones are single. This stout snake, usually between in total length (including tail), reaches a maximum total length of in males and in females. The largest specimen on record measured approximately . Gloyd HK, Conant R (1990). ''Snakes of the ''Agkistrodon'' Complex: A Monographic Review''. Society for the Study of Amphibians and Reptiles. 614 pp., 52 plates. LCCN 89-50342. .

Common names

Common names for ''D. acutus'' include sharp-nosed viper, snorkel viper, hundred pacer,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . Chinese moccasin,''Deinagkistrodon acutus''
a
Armed Forces Pest Management Board
Accessed 30 May 2007. Chinese copperhead,Gotch AF (1986). ''Reptiles – Their Latin Names Explained''. Poole, UK: Blandford Press. 176 pp. . five-pacer, hundred-pace snake, long-nosed pit viper, sharp-nosed pit viper,United States Navy (1991). ''Poisonous Snakes of the World''. New York: US Government New / Dover Publications Inc. 203 pp. . hundred-pace pit viper.Gumprecht A, Tillack F, Orlov NL, Captain A, Ryabov S (2004). ''Asian Pitvipers''. Berlin: GeitjeBooks. First Edition. 368 pp. .
The snake has been an object of veneration by indigenous Taiwanese peoples.

Geographic range

''Deinagkistrodon acutus'' is found in southern China (Zhejiang, Fujian, Hunan, Hubei, Guangdong), Taiwan, northern Vietnam, and possibly Laos. The type locality was not included in the original description. It was later given as "Wusueh u-hsueh Hupeh Province, China" by Pratt (1892) and Pope (1935). Listed as "Mountains N. of Kiu Kiang" in the catalogue of the British Museum of Natural History.

Habitat

The species ''D. acutus'' inhabits high, forested mountains up to , but has also been found in low coastal regions (). It prefers lower mountain slopes or rocky hills with small valleys.

Diet

The diet of ''D. acutus'' consists of small mammals such as rats and mice, birds, toads, frogs and lizards. Chinese herpetologist Er-mi Zhao reported a specimen of a total length of and weighing having eaten a specimen of ''Rattus rattus'' of a total length of and a weight of .

Reproduction

As one of the few oviparous pit vipers, ''D. acutus'' can lay up to 24 eggs, which may be retained during initial incubation, an adaptation that shortens post-deposition incubation time. However, it generally only deposits 11 or 12 eggs from June to August. Egg size is 40–56 x 20–31 mm (about 2 × 1 in). Hatchlings are lighter and more vividly patterned than the adults, but this darkens considerably with age.

Venom

Dangerous animals often have exaggerated reputations and the species ''D. acutus'' is no exception. The popular name "hundred pacer" refers to a local belief that, after being bitten, the victim will only be able to walk 100 steps before dying. In some areas, it has even been called the "fifty pacer" or, in extreme examples, the "five-step snake." This often causes bite victims to needlessly amputate or burn bitten fingers or limbs, resulting in further complications like the loss of the amputated body part or gangrene. Nevertheless, this species is considered dangerous, and fatalities are not unusual. An antivenom is produced in Taiwan.

Brown (1973) mentions a venom yield of up to 214 mg (dried) and (toxicity) values of 0.04 mg/kg IV, 4.0 mg/kg IP and 9.2–10.0 mg/kg SC.Brown JH (1973). ''Toxicology and Pharmacology of Venoms from Poisonous Snakes''. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73–229. . The venom contains at least four hemorrhagins Acutolysin A, B, C and D.

According to the US Armed Forces Pest Management Board, the venom is a potent hemotoxin that is strongly hemorrhagic. Bite symptoms include severe local pain and bleeding that may begin almost immediately. This is followed by considerable swelling, blistering, necrosis, and ulceration. Systemic symptoms, which often include heart palpitations, may occur suddenly and relatively soon after the bite. Because of its body size and large hinged fangs which permit effective delivery of large quantities of venom, victims bitten by this snake should be treated accordingly.

Venom use in research and medicine

The venom of this species is commonly used for research purposes. Researchers have found that this venom contains protease activity, meaning it attacks and degrades intra- and extracellular proteins. If injected into mice, within 2 hours the venom begins a process known as mesangiolysis (the degeneration and death of cells that line the inner layer of the glomerulus and regulate glomerular filtration in the kidney). Eventually, the kidneys no longer function and the mouse dies.

When controlled, the venom has some clinical application. ''D. acutus'' snake venom contains a protein called ACTX-6. This protein was shown to induce apoptosis (cell death) in isolated cancer cells through Fas pathway activation. Fas is a protein that becomes a death receptor in the cellular membrane. When activated, Fas turns on what is called a "caspase cascade".Weinberg, Robert A. The Biology of Cancer. Garland Science, Taylor and Francis Group.(2007);343–350. . This pathway is made up of a series of proteins called initiator and executioner caspases. Initiator caspases help form an apoptosis initiation factor that eventually activates executioner caspases (see figure 3). Executioner caspases go on to "digest" the cell from the inside out. They cleave cytoskeleton filaments and DNA until the cell completely implodes.

Venom and traditional Chinese medicine

''Deinagkistrodon acutus'' venom has been used in traditional Chinese medicine for centuries to extract antivenin that is successfully used to treat snakebites. Different parts of the snake are also prescribed to help alleviate ailments known as "wind diseases". Because these snakes move so quickly, substances from their bodies are thought to easily treat these fast-moving "wind" syndromes. ''D. acutus'' is currently used in patients with arthritis, leprosy, tetanus, boils, and, as previously mentioned, tumors.Subhuti Dharmananda, PhD The Medicinal Use of Snakes in China. Institute for Traditional Medicine, Portland, Oregon. May 199

/ref> The same qualities that make snakes flexible, capable of regenerating skin, and able to inflict paralysis could be transferred to human conditions if applied medicinally."Agkistrodon acutus pit vipers." Medical-Explorer.com; accessed April 2010

/ref> The vipers are prepared by cooking the flesh of the headless body, grinding a paste of snake ash and mixing it with honey, drying the snake and compacting it into a powder, or even injecting their venom intravenously. Although these practices are common in Chinese medicine, no current studies have affirmed the effectiveness of these treatments. Whether these "cures" simply have a placebo effect or actually heal the patients is not known.

References

Further reading

* Boulenger GA (1896). ''Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the ... Viperidæ.'' London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiv + 727 pp. + Plates I–XXV. (''Ancistrodon acutus'', new combination, p. 534).
* Gloyd HK (1979). "A new generic name for the hundred-pace viper". ''Proc. Biol. Soc. Washington'' 91: 963–964. (''Deinagkistrodon'', new genus).
* Günther A (1888). "On a Collection of Reptiles from China". ''Annals and Magazine of Natural History, Sixth Series'' 1: 165–172 + Plate XII. (''Halys acutus'', new species, pp. 171–172 + Plate XII).
* Pope CH (1935). ''The Reptiles of China: Turtles, Crocodilians, Snakes, Lizards''. (Volume X of the Natural History of Central Asia series, edited by Chester A. Reeds). New York: American Museum of Natural History. lii + 604 pp + Plates I–XXVII. (''Agkistrodon acutus'', pp. 387–390 + Plate XXIII, figures D-G).

External links

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*. Accessed 6 August 2007.
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{{Taxonbar, from=Q716476

Crotalinae
Monotypic snake genera
Reptiles of China
Reptiles of Taiwan
Reptiles of Vietnam
Taxa named by Howard K. Gloyd
Snakes of China
Snakes of Vietnam
Snakes of Asia