Scientists decoded the mysteries of Okinawan Habu venom

Accelerated evolution of venom protein genes.

Scientists decoded the mysteries of Okinawan Habu venom
Image: OIST

Habu snakes, which are more often found in Okinawa, have 3 species. Two of these species have been introduced and one is native to the island. Among all, the Okinawan habu (Protobothrops flavoviridis), endemic to the Ryukyu islands, is highly venomous.

Now, a team of Japan scientists has mapped the entire genome of the Habu. To do so, they primarily collected Okinawan habus from the wild using a long metal pole with a hook at one end and collected venom, blood and tissues samples from them. Then by using DNA sequencing technique, scientists identified scientists identified nearly 60 genes from 18 different gene families that help this critter make its venom.

The Okinawan habu is endemic to the Ryukyu islands of Japan. It is the longest and the most venomous of the three habu species found in the region.  Credit:  Prof Hiroki Shibata
The Okinawan habu is endemic to the Ryukyu islands of Japan. It is the longest and the most venomous of the three habu species found in the region.
Credit:
Prof Hiroki Shibata

After biting, the Okinawan Habu venom destroys the blood cells and tissues. Although, the antinodes are available, but still, the bite causes severe pain and can cause permanent damage.

Professor Nori Satoh from Okinawa Institute of Science and Technology Graduate University (OIST) said, “the findings of this study are very important, especially to the people of Okinawa and the surrounding islands where the Okinawan habu is found.”

Prof. Hiroki Shibata, a collaborator from the University of Kyushu said, “Though the Okinawan habu is not as venomous as cobras or taipans, it can produce a large amount of venom – up to 1 ml. Its long, sharp fangs help discharge the venom deep inside the prey.”

The scientists investigated this current venom’s developmental history by building a phylogenetic tree of venom genes including those that they recognized in the habu. A phylogenetic tree shows the connection between at least two or more organizations by distinguishing the likenesses and dissimilarities between them. The separation between the groups in a tree means diverse degrees of relatedness between them. The gatherings that are firmly set are more identified with each other than those put assist away.

The Okinawan Habu can produce a large amount of venom. The venom is hemotoxic and destroys the blood cells and tissues of the prey.  Credit:  Prof Hiroki Shibata
The Okinawan Habu can produce a large amount of venom. The venom is hemotoxic and destroys the blood cells and tissues of the prey.
Credit:
Prof Hiroki Shibata

Venomous snakes across the world belong to one of the two families; Viperidae or Elapidae. The members of the family Viperidae, including the habu, have venom that is toxic to blood (hemotoxic); whereas the members of the family Elapidae, such as cobras, have venom that is toxic to the nervous system (neurotoxic). In this study, the researchers found many common components among venom genes of both families, thereby tracing back the origin of the present-day venom toxins to a common ancestor that existed millions of years ago.

Prof. Shibata said, “The venom gene copies originated a long time ago, possibly at the early stage of vertebrate evolution.”

Members of the OIST Marine Genomics Unit and the DNA Sequencing Unit were a part of this collaborative study. From left to right: Professor Nori Satoh, Ms. Kanako Hisata, Dr. Ryo Koyanagi, Mr. Shinichi Yamasaki, Mr. Manabu Fujie and Dr. Takeshi Takeuchi.
Members of the OIST Marine Genomics Unit and the DNA Sequencing Unit were a part of this collaborative study. From left to right: Professor Nori Satoh, Ms. Kanako Hisata, Dr. Ryo Koyanagi, Mr. Shinichi Yamasaki, Mr. Manabu Fujie and Dr. Takeshi Takeuchi.

The study is published in Scientific Reports.