LD50 rating for European vipers

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Re: LD50 rating for European vipers

Postby Mario Schweiger » Tue Jul 19, 2016 7:10 pm

maybe, this could be of interest:

Author: Guillemin, I., C. Bouchier, T. Garrigues, A. Wisner & V. Choumet
Year of publication: 2006
Title: Sequences and structural organization of phospholipase A2 genes from Vipera aspis aspis, V. aspis zinnikeri and Vipera berus berus venom. Identification of the origin of a new viper population based on ammodytin I1 Heterogenety.
Journal: Eur. J. Biochem. 270, 2697–2706
Abstract: We used a PCR-based method to determine the genomic DNA sequences encoding phospholipases A2 (PLA2s) from the venoms of Vipera aspis aspis (V. a. aspis), Vipera aspis zinnikeri (V. a. zinnikeri), Vipera berus berus (V. b. berus) and a neurotoxic V. a. aspis snake (neurotoxic V. a. aspis) from a population responsible for unusual neurotoxic envenomations in south-east France. We sequenced five groups of genes, each corresponding to a different PLA2. The genes encoding the A and B chains of vaspin from the neurotoxic V. a. aspis,PLA2-IfromV. a. zinnikeri,and the anticoagulant PLA2 from V. b. berus are described here. Single nucleotide differences leading to amino-acid substitutions were observed both between genes encoding the same PLA2 and between genes encoding different PLA2s. These differences were clustered in exons 3 and 5, potentially altering the biological activities of PLA2. The distribution and characteristics of the PLA2 genes differed according to the species or subspecies. We characterized for the first time genes encoding neurotoxins from the V. a. aspis and V. b. berus snakes of central France. Genes encoding ammodytins I1 and I2, described previously in Vipera ammodytes ammodytes (V. am. ammodytes), were also present in V. a. aspis and V. b. berus. Three different ammodytin I1 gene sequences were characterized: one from V. b. berus, the second from V. a. aspis, V. a. zinnikeri and the neurotoxicV. a. aspis, and the third fromthe neurotoxic V. a. aspis. This third sequence was identical with the reported sequence of the V. am. ammodytes ammodytin I1 gene. Genes encoding monomeric neurotoxins of V. am. ammodytes venom, ammodytoxins A, B and C, and the Bov-B LINE retroposon, a phylogenetic marker found in V. am. ammodytes genome, were identified in the genome of the neurotoxic V. a. aspis. These results suggest that the population of neurotoxic V. a. aspis snakes from south-east France may have resulted from interbreeding between V. a. aspis and V. am. ammodytes.

PDF to download: http://www.vipersgarden.at/PDF_files/PDF-713.pdf
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Re: LD50 rating for European vipers

Postby Guillaume Gomard » Tue Jul 19, 2016 7:17 pm

Niklas Ban wrote:The variation in venom is so huge in even one species, that this lists are very imprecisely without exact location and subspecies.


Not to mention variation in venom composition and toxicity for a given specimen between juvenile and adult stages.

Will Atkins wrote:this begs the question as to why there is so much intraspecific variation in venom - surely not differences in feeding


Could also be to some extent, venom composition does change with the diet (typical example is shift from invertebrates at early stages to rodents for older specimens).

On the topic, I read som time ago an interesting conclusion (not driven from the snakes case but from Conus ebraeus). According to the authors of this study: "changes in gene expression contribute to intraspecific variation of venom composition and that gene expression patterns respond to changes in the diversity of food resources during different growth stages."

source: Chang, Dan, and Thomas F. Duda. "Age-related association of venom gene expression and diet of predatory gastropods." BMC evolutionary biology 16.1 (2016): 1.
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Re: LD50 rating for European vipers

Postby Niklas Ban » Tue Jul 19, 2016 7:26 pm

Guillaume Gomard wrote:
Niklas Ban wrote:The variation in venom is so huge in even one species, that this lists are very imprecisely without exact location and subspecies.


Not to mention variation in venom composition and toxicity for a given specimen between juvenile and adult stages.

yes of course, how could I forget this point!
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Re: LD50 rating for European vipers

Postby Will Atkins » Tue Jul 19, 2016 7:40 pm

As always, I am amazed by the collective wisdom of you all!! thank you!

@Mario - aspis x ammodytes may have led to the increased potency of the SE France aspis populations - very interesting - as usual I was behind the curve when thinking out loud that maybe venom genes could be used to track evolution / taxonomic decisions...

@Guillaume - a very nice example of epigenetics, thank you for this information.
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Re: LD50 rating for European vipers

Postby Berislav Horvatic » Tue Jul 19, 2016 9:55 pm

We were prompted to carry out this study by the recent identification of a distinct,
unusually neurotoxic population of V. a. aspis in the south-east of France [12].
Several cases of envenomation resulting in symptoms of neurotoxicity have been
reported in recent years in two French de´partements (Alpes-Maritimes and Alpes
-de-Haute-Provence). Such symptoms have never been observed after envenomation
by V. a. aspis snakes in other regions of France.
These results suggest that the population of neurotoxic V. a. aspis snakes from south-east
France may have resulted from interbreeding between V. a. aspis and V. am. ammodytes.

But where is the (present) contact zone of V. aspis and V. ammodytes IN FRANCE, anywhere,
south-eastern or not?
Also, the neurotoxic component of the venom of V. ammodytes is rather weak - or isn't it?
So, why should it be more pronounced/efficient in a hybrid than in the "pure form"?
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Re: LD50 rating for European vipers

Postby Guillaume Gomard » Wed Jul 20, 2016 7:04 am

Berislav Horvatic wrote:the neurotoxic component of the venom of V. ammodytes is rather weak - or isn't it?


It's weak with respect to elapids, etc. but significant enough to report an important number of symptoms among patients. An illustration among others:

"A recent retrospective analysis of 542 envenoming snakebites in southern Croatia (total population, ∼500,000) reported a mean annual incidence of bites of approximately 5 per 100,000. The most common signs and symptoms were coagulopathy, extensive swelling and edema, ecchymosis, and regional lymphadenitis, but clinical signs and symptoms of neurotoxicity such as ptosis, ophthalmoplegia, dysphagia, dysphonia, and neuromuscular weakness occurred in as many as 16% of the cases (2, 3)

(from Logonder, Uroš, et al. "Neurotoxicity of ammodytoxin A in the envenoming bites of Vipera ammodytes ammodytes." Journal of Neuropathology & Experimental Neurology 67.10 (2008): 1011-1019.)

Berislav Horvatic wrote:But where is the (present) contact zone of V. aspis and V. ammodytes IN FRANCE, anywhere,
south-eastern or not?


Good question, a contact zone could have occurred in South East (close to Italy) but I also don't get the origin in South West France...
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Re: LD50 rating for European vipers

Postby Berislav Horvatic » Wed Jul 20, 2016 3:03 pm

Guillaume Gomard wrote:Good question, a contact zone could have occurred in South East (close to Italy)
but I also don't get the origin in South West France...

But Guillaume, nobody mentioned the southWEST of France regarding this issue...
Even the southeast of France is well separated from the westernmost habitats
of V. ammodytes in Italy.
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Re: LD50 rating for European vipers

Postby Guillaume Gomard » Wed Jul 20, 2016 5:23 pm

Hi Bero,

Maybe we have a quiproquo here: I did not speak about the current distribution of both vipers but the fact that they could have co-existed in the East of France in ice refuges. This may explain the neurotoxicity of certain V.a.aspis populations on the East but still, it does not clarify the V.a.zinnikeri case.
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Re: LD50 rating for European vipers

Postby Berislav Horvatic » Wed Jul 20, 2016 8:25 pm

Guillaume Gomard wrote:... but still, it does not clarify the V. a. zinnikeri case.

Which is?
(Sorry if it's well-known and/or obvious to some of the professionals, but it isn't to me.
Really not teasing anybody, just willing to understand. So, please enlighten me.)
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Re: LD50 rating for European vipers

Postby Will Atkins » Wed Jul 20, 2016 10:13 pm

Dear Berislav - I think Guillaume is referring to Jeroen's earlier comment that Vipera aspis zinnikeri is reputed to have a much more potent venom than aspis aspis, hence the question arises as to where the genes coding for those specific components in the zinnikeri venom might have come from.

On the question of 'ammodytes' genes for venom in SE populations of aspis, could it not perhaps be that 'ammodytes genes' are not the same as Vipera ammodytes? maybe these signature genes pre-date the extant species that we refer to as Vipera ammodytes? perhaps some ancestral species of Vipera even which branched into aspis and also ammodytes. Or maybe I'm being a bit too Dawkins-esque by considering the gene rather than the whole animal... ;) !

Pure speculation, just thinking out loud..
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