It is common knowledge that to anger a bee is a bad idea as in situations of danger or in response to attack pheromones, the bee may sting you, injecting you with its venom, apitoxin. In the case of a jellyfish, stinging is a self-defence mechanism and is also employed in order to incapacitate prey. However, the mechanism by which they achieve this is much less well-known.
It is by the firing of many tiny harpoon-like structures from specialised organelles named nematocysts that jellyfish elicit such a sting. The force by which these projectiles are expelled from the nematocyst is comparable to the firing of a bullet from a gun, and can therefore even penetrate the shell of Crustacea. Prior to discharge, the tubular structure of the “harpoon” is coiled within the nematocyst capsule and is surrounded by a potentially lethal matrix containing a smorgasbord of toxins, much like the apitoxin of bees.
The initial symptoms which arise after being stung, such as swelling, redness and a burning sensation can be attributed to your body’s immune response. Water rushes to the area in an attempt to flush the toxins from the affected area, while histamines are released resulting in vasodilation and increased permeability of the blood vessels to white blood cells. However, other more serious effects are possible such as neurological and cardiovascular complications and potentially fatal haemolysis.
Haemolysis is the rupturing of red blood cells. Small proteins within the venom of animals such as jellyfish and bees are the culprit for this nasty effect and cause this by forming tiny pores within the membrane of the red blood cells. Melittin is the major toxin found in bee venom. It is a small peptide of 26 amino acids and has a strong hemolytic potency. The 26 amino acid chain folds to form an amphipathic alpha helix – i.e. the protein has a net positive charge on one side, and a net negative charge on the other. This characteristic facilitates its insertion into the cell membrane which is comprised of a mosaic of similarly amphipathic phospholipids. In a concentration dependent manner, melittin subsequently forms stable pore-like structures within the red blood cells membrane, allowing for the diffusion of water and ions in and out of the cell, resulting in osmotic swelling and lysis of the cell.
There are many more toxins with a wide diversity of mechanisms which I would like to cover at some point in the future. Until then, I hope this short piece has helped you to understand a little more about bees, jellyfish and how they succeed in causing us the most horrific of pains. The little blighters.
Till the next time,
Beckmann A, & Özbek S (2012). The nematocyst: a molecular map of the cnidarian stinging organelle. The International journal of developmental biology, 56 (6-8), 577-82 PMID: 22689365
Matsuzaki, K., Yoneyama, S., & Miyajima, K. (1997). Pore formation and translocation of melittin Biophysical Journal, 73 (2), 831-838 DOI: 10.1016/S0006-3495(97)78115-3
Raghuraman H, & Chattopadhyay A (2007). Melittin: a membrane-active peptide with diverse functions. Bioscience reports, 27 (4-5), 189-223 PMID: 17139559
Ozbek S (2011). The cnidarian nematocyst: a miniature extracellular matrix within a secretory vesicle. Protoplasma, 248 (4), 635-40 PMID: 20957500