Alright guys, here’s my 2nd post of the Biology series which is related to none other than the famous Shiitake mushroom, Fungi. Various cartoon or animation characters are taken from this group of species and as an example, I have embedded a picture of Parasect on the left side of this paragraph. Parasect is an example of several mushroom related Pokemons apart from Shroomish, Breloom, Foongus, Amoongus, Shiinotic, Morelull and it's pre-evolved form Paras. The Pokemon game Ruby, which many of you might be familiar with describes Parasect as it is able to "infest large trees en masse and drain nutrients from the lower trunk and roots". We shall explore on how these nasty but adorable beings are able to do so later.
For approximately a billion years, fungi is a well-known group of organisms that could break down substances. In fact, they have been acknowledge and awarded with their own distinct kingdom, which is separated from plants and animals. These amazing life-forms break down carbon compounds and return carbon and other elements to the surroundings to be used by other creatures. Quite a help eh? However, one should not be fooled by its seemingly harmless appearance. As I said earlier, but this time with more exaggeration, fungi could destroy even the most enormous trees and it is able to cause life threatening brain abscess to humans.
What makes them different?
For centuries, they were classified under the plant kingdom until recently. Contrary to those plants, they are heterotropic which means that they are unable to synthesize their own food. Harshly speaking, they are parasites to many living things in this world. Above 80 000 different species of Fungi has been identified in the fungi kingdom. Taxonomists even believe that there are up to 1 500 000 fungi species. Many have yet to be discovered. Similar to animals, they use glycogen for storing energy reserves and their cell walls are made of chitin. Chitins are one of the substance that covers the insect’s outer shells.
Fungi can thrive in wide array of environment, especially in moist and dim places. They grow well in temperature ranges from 4 degrees to 60 degrees celcius. They also can live high up till 4000m above sea level, which some plants and animals are unable to do so. Quite persistent aren’t they?
The most famous fungi is none other than the Basidiomycota group. Mushrooms are under this category. The mushroom’s reproductive organ is its cap and the cap protects the Basidia. Basidia is their spore forming anatomical part. Hymenium is located on the underside of the cap. It contains very fine tissues that generate spores. The structure can consist of tubes, wrinkles, hair-like projections, and even needles. Below down is their ring which is also known as the veil. It protects part of the hymenium in young fungi. The stem is similar to plants, as it provides support to the structure. The volva is located at the base, it is made of the remnants of early rings those which have withered before.
Take Chytridiomycota as an example. They are the only fungi with mobile cells- male and female gametes. They release these gametes into water in order to reproduce. In the same reproductive phase, they can produce haploid and diploid spores.
Deuteromycota is famously called as the imperfect fungi. The labeled name is due to the fact that they are unable to reproduce sexually. Their anatomical parts include the conidiophore, hypha and mycelium. Their asexual spores are located in their conidiophores. Their existence are harmful to humans. They live as parasite to humans, animals and plants. Mycosis is the medical term for fungal infection, and this organism can cause infection to the human skin. I’m going to insert some medically related facts as I go along in this blog because I have a medical background, so I would love to share it to my fellow Steemers. Luckily for human beings, they too brought the cure to the rampant bacterial infections. Penicillium, which is categorized under this group, is blessed with the ability to produce the very first medication that combats against Staphyloccoci and Streptococci bacterias, which is Penicillin. Imagine if they do not discover this Holy Grail, many humans would have died from just a simple bacterial infection. Penicillin is broadly used nowadays and because of that, many bacteria are evolved to counter its beta lactam properties.
Zygomycota on the other hand, is a phylum of land-growing fungi. They reproduce through sexual means and their diploid cells do not break their cell walls until the environment is suitable for them to germinate. They also have the capability to reproduce asexually. Their anatomical parts include the sporangium, sporangiophore and the mycelium.
Ascomycota is the group of fungi with the most species. Yeasts, molds, morels, truffles are included in this phylum or group. Their anatomical parts include the Ascus, which is on top of each Hyphaes. Ascocarp is their base. Their hyphaes are segmented into partitions and their asexual spores (Conidia) are mini-sized and formed at the ends of each Hyphaes.
What does the Fungi feeds on?
As I have mentioned earlier, they do not produce their own food unlike plants. They too, do not ingest their food unlike animals. On the contrary, they absorb their foods after breaking it down into small molecules. Many of their food sources are dead organic materials. Some other fungi are parasites and some establish relationships of mutual benefit or mutualism with bacteria, algae, or plants.
How do they feed?
Fungi produces their own digestive enzymes on the food source. This causes a chemical transformation which results in smaller, and easily assimilated product. Easy for them to digest. They will first begin by generating a great network of hyphaes, branching filaments that extend into the surrounding medium. Similar concept as the plant’s roots. This massive network of hyphae is known as mycelium. The mushroom is formed when the threads of mycelium are dense and compacted. As a result, they will grow upwards to create a fruiting body. Interestingly for Basidiomycetes, they are categorized according to their own dietary needs. As an example, they colonize various parts of the tree which is solely depending on their nutrients that they require. Several fungi species actually feeds on petroleum and even plastics. Currently, scientists are searching for possibilities of using petroleum-digesting fungi to clear up oil spills and other chemical calamities. Fungi is amazing, indeed.
Life cycle
In general, the life cycle involves the fusion of hyphae from two individuals. This process is known as Plasmogamy. This will then form mycelium that contains haploids from both individuals. The fused Hyphae is now called as Heterokaryotic as they contain two haploid nuclei. In some species, Plasmogamy results in cells with one nucleus from each individual, this is known as Dikaryotic. Eventually, both nuclei that comes from different individuals fuse to form a diploid zygote. Similar to humans, meiosis comes after the process. The outcome will be either four haploid nuclei or four haploid cells. That’s cell division for you guys. I bet many have learnt it back during your biology classes but this is the fungi’s version. After the fertilization process, they will release spores and dispersed by wind. The new spores are capable to germinate and to form new Mycelium.
They can be cute and colourful, let’s not forget about their pathogenic capabilities. They exert their monstrous effects not only just to the human body, but towards the agriculture sector too.
Let’s take the Basidiomycota as an example. Basidiomycota such as Cryptococcus Neoformans is an encapsulated yeast. The infection that caused by this organism is known as Cryptococcosis. Most of the infection involves the lungs and some even travels to the brain causing Cryptococcus meningitis/encephalitis. Most fungal infections are opportunistic, as they show their true colours when the affected individual’s immune system is impaired. Hence that’s the reason why Cryptococcosis is more common in AIDS patients. Cryptococcosis can be detected via Cryptococcal Antigens or by cultures. Via microscopy, an India Ink stain of the CSF (cerebrospinal fliud) can reveal the organism.
Next is Ascomycota. Some of them are dermatophytes. Dermatos means skin and phyte means plant. Basically, they cause skin infection. Apart from skin, they do affect other keratinized body parts such as hair and nails. They produce acid proteinases, elastases, and keratinases to break down proteins and keratin (which are abundant in our skin). Toenail and fingernail infections are called onychomycosis. There are several types of dermatophyte infections, namely:
- Tinea Pedis or Athelete’s foot
- Tinea Cruris or Jock’s itch
- Tinea Corpora or the ringworm of the body
- Tinea Capitis or Blackdot ringworm
- Tinea Faciei or Facial ringworm
- Tinea Manuum or ringworms of the hands
They are usually transmitted via direct contact with the infected individuals or indirect contacts with affected household objects. Some Ascomycota such as Aspergillus species causes Aspergillosis. There is about 900 Aspergillus species and most of it is associated with human illnesses. Aspergillus flavus is associated with allergic reactions with individuals with genetic predisposition. They produce secondary metabolites which are known as micotoxins. Bread mold or Aspergillus niger found in mould-covered foods. Their fruiting body is yellowish-white and turns black when the Conidia matures. That explains why bread mold turns black after some time. Aspergillosis are demonstrable via silver stains. They stain the fungal wall grey-black.
The last famous organism in this list is none other than the Candida albicans . Candida comes from the Latin word “Candidus”, which means white. Albicans itself means white in Latin. Hence they are one of the tautology terms. Tautology is a statement with repeated or redundant meanings. Cool eh? They are one of the Ascomycota as well. This fungus is a common member in the human gut flora and does not grow outside of the human body. They are usually harmless, commensal organism. However, when the body’s immune system is compromised, they can be very pathogenic. Like other opportunistic infections, they are commonly found in AIDS patients. In fact it is one of the cause of death in HIV-infected individuals. Diagnosing yeast infection is done via microscopic examination or culturing.
To identify the organism via microscopy, a scrapping or a swab can be taken and the sample is visualized under a slide. A single drop of 10% Potassium Hydroxide (KOH) dissolves the human skin cells, and permits the Candida to be visualized. The methods of treatment might be posted in the future in my Pharmacological blog posts.
In a nutshell, fungi is an interesting creature. Despite their subtle appearance to the naked eye, they can cause a lot of chaos to a person, especially those with weak immune system. Some fungi are even poisons to humans. Nevertheless, fungi brought a vast amount of boon to human beings as they are prominently cultivated for miscellaneous amount of dishes, valuable anti-microbials those could prevents mortality, and they are even used as insecticide to deter away pests. So, friends or foes? Similar like fire, as long as you know how to handle this precious little creature, everything will be just fine. Alright, so that's all for today. Have a great time !
References
- Our Earth. China: Parragon Books, 2013. Print
- Ascomycota. Barnard Health Center. Retrieved on April 6, 2018, from https://www.barnardhealth.us/microbial-growth/ascomycota.html
- Deuteromycotina. Materi dan Soal IPA UTK SMA. Retrieved on April 6, 2018, from http://fiskadiana.blogspot.my/2015/05/deuteromycotina-dan-lichenes.html
- Life Cycle of Fungi. Encyclopaedia Britannica. Retrieved on April 6, 2018, from https://www.britannica.com/science/fungus/Life-cycle-of-fungi
- Importance of Fungi in Human Life. Boundless Biology. Retrieved on April 6, 2018, from https://courses.lumenlearning.com/boundless-biology/chapter/importance-of-fungi-in-human-life/
- Life Cycle of Fungi. Biolympiads. Retrieved on April 6, 2018, from https://biolympiads.com/2014/09/life-cycles-of-fungi.html