Why school biology textbooks need to redraw the plant and animal cell

Does anyone remember what a catalase is? It’s one of the most popular antioxidant enzymes there is. I still remember doing one of my Biology A-level (college) assignment where we measured the rate of hydrogen peroxide breakdown by the enzyme catalase. Throughout my school, I was *incorrectly* taught that catalase is an enzyme found in the liver. Even during my undergraduate, I didn’t know much more about this enzyme and still thought that it was an enzyme found in liver cells. But catalase is an enzyme that resides inside the ‘peroxisome’ – no, it’s not the name of an alien structure but the peroxisome is an essential cellular compartment in all eukaryotes that include all animals, plants, fungi and other organisms which contain advanced cells containing a cellular structure called the nucleus.

Most people are rightly familiar with other cellular compartments like the endoplasmic reticulum, Golgi, mitochondria, chloroplast, vacuole, plasma membrane and the cell wall. These cellular structures are indeed very important, if not essential, to the function of the cell, whether it be the animal cell or the plant cell. There’s, however, a cellular compartment that’s missing from the list above – the compartment that is equally if not more important than most on the list – that compartment is indeed the peroxisome.

A few months ago, a eukaryotic organism living in guts of chinchilla was found not to contain any mitochondria, which made major headlines. But it’s beyond my understanding why peroxisomes that are also found ubiquitously in eukaryotes, except in a handful of organisms, are not even mentioned to science students. Without peroxisomes, we’d all die. Without peroxisomes, plants (our food source) would also die, and plants really are tough survivors that can live in some extreme conditions. In summary, peroxisomes are as important as they are common and are required for our survival and for our food.

Peroxisomes: why should you care?

Peroxisomes perform a wide range of important metabolic functions that keep the plant and our bodies in check. The most important functions of the peroxisome include the breakdown of fatty acids to produce sugars and to break down toxic waste product hydrogen peroxide into water and oxygen. It’s easy to imagine that without peroxisomes, there would be an excess build-up of fats and toxic hydrogen peroxide in cells, which isn’t good news for either plants or us.

Yes, we need peroxisomes to live and to grow food but there are a lot of other factors that are required for our survival. So, why should we care? Surely scientists and doctors know about how important they are, right? I wish this was true but unfortunately, a lot of biologists and doctors aren’t even familiar with peroxisomes and the diseases that can occur if body peroxisomes are not functioning properly. Faulty peroxisomes cause severe disease in humans that usually cause death within a year of birth but the awareness of the group of peroxisome biogenesis diseases is very poor. Perhaps the reason for this is because the awareness of peroxisomes itself is extremely poor. And so, if a child suffers kidney failures, loss of hearing/eyesight or liver failure, you don’t usually think “it must be a peroxisome biogenesis disorder.”

Media isn’t responsible for the lack of awareness on peroxisome diseases. Education policymakers are.

Peroxisome diseases are rare and affect 1 in 50,000 people. Due to this, there aren’t many specialists around, so the diagnosis is difficult and considerably delayed. Peroxisome diseases range from mild symptoms ranging from hearing loss, loss of eyesight to severe conditions leading to kidney, liver failure, reduced brain development etc. Despite it being a serious, life-threatening disease it is hardly reported in the media, which is frustrating to people/families affected by these diseases and is partly why there isn’t much awareness on these diseases.

Peroxisomes for all

Despite the significance of peroxisomes for the survival of many different organisms, our scientific knowledge on their formation, maintenance and functions remain poor. This could also be linked to the lack of awareness about peroxisomes to school and college students, who are not drawn towards peroxisome research simply because they don’t know what a peroxisome is. For example, the biennial peroxisome conference only had under 100 participating scientists this year, in comparison, the annual mitochondria conference has over 350 participants this year. Clearly, peroxisome research is neglected and peroxisome research field is lagging far behind the other cellular compartments, which further makes it harder for an effective gene therapy to be developed for peroxisome diseases.

Participants of the Open European Peroxisome Meeting 2016, Vienna, Austria. Photo courtesy Prof Johannes Berger.
Participants of the Open European Peroxisome Meeting 2016, Vienna, Austria. Photo courtesy Prof Johannes Berger.

Research into peroxisomes will not only help the survival of humans but will allow us to improve crop yields. And since peroxisomes are also present in fungi and protozoan parasites that infect humans, it is possible to target unique peroxisomal features in them to develop drugs or therapy against diseases caused by these organisms. Extensive research in peroxisomes will allow us to do this one day. Research presented in the last peroxisome conference identified drugs that uniquely target the peroxisome in trypanosomes that cause the African Sleeping Disease. Without peroxisomes, these trypanosomes aren’t able to survive so these results are really promising and may be translated to other organisms.

So, clearly, peroxisomes are highly important and are central to our health, food supplies and in disease prevention. I believe that they should be a common knowledge amongst all people and especially students whether they are in high school or in universities. And perhaps with higher awareness on peroxisomes, we might get higher media attention on peroxisome disease that may save lives, have more scientists working on peroxisome research, which will be better for everyone.

It’s now time for education policymakers to acknowledge the existence of peroxisomes and redraw the cell biology textbooks throughout the world to include the peroxisome in the illustration of the animal and the plant cell.

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