Looking into a microscopic world
Nandini Dholepat
Sitting in the Gymnosperm garden, Anand and Vivan discussed with each other and drew a diagram of simple to complex life forms. Raja added a timeline to the diagram.
“Great! This gives clarity on how different forms of life evolved on Earth. So, with this evidence, we now have come to an understanding that human beings are highly evolved, we are not struggling for survival and are fighting for our greed and not need,” said Madhavi.
“True, if we neglect these less understood forms, which support the survival of all other higher organisms, we will lose everything soon,” I replied.
“But how? We are growing ferns in gardens,” Rini commented innocently.
Raja tried to explain, “In natural ecosystems, algae, bryophytes, and pteridophytes play a major role. They provide food for small animals. Their continued presence in the ecosystem confirms the existence of pure water, fish, mussels, prawns, and other such dependents. They are all very delicate. If the water gets contaminated or the water flow reduces, plants will wither away and animals and insects will eventually vanish.”
“There was a time I used to think that all this greenery was only ornamental and not of much use beyond that. Our approach towards human-centered conservation should change,” Sujatha said.
“Let’s get a move on. I got a message from my colleague Jayanthi, we can go to the lab,” Raja said.
“What is this? Looks like a tiny fruit,” Vivan pointed at a plant at the entrance of the staircase.
This is ‘Taxus’, it is a gymnosperm,” I replied.
“It was brought from Arunachal Pradesh, from a high altitude. Fortunately, it is surviving even in this environment. It is actually a tree, but as it is pruned regularly, it doesn’t grow tall. And what you think is a fruit, is a scale. It is a protective covering over the bud, that turned out fleshy here. You can see an opening and a seed inside. Birds eat the seeds and help in their dispersal,” said Raja.
Inside the building, we were asked to sit on a bench. Frames of famous scientists adorned the wall. Anand pointed to a photograph, “See, this is Alexander Fleming, he invented Penicillin. The same picture is in my textbook.”
“I know the person in the left photograph. It is Charles Darwin, who proposed the theory of evolution,” Rini also showed off her knowledge.
“Hi everyone, I am Jayanthi. I am a researcher in the microbiology lab. Before we go in, please keep your bags in these cupboards. Just carry your notebooks and pencils, and remove your footwear and wear these.” Jayanthi pointed to the slippers kept for visitors. Then, she asked us to wash our hands and gave us face masks. She led us to the lab and informed us about their regular activities. She also showed us how to place a specimen on the microscope and adjust the microscope to observe the specimen.
Raja called everyone, “Come here, take a look at this. I have placed a water drop collected from the pond on a glass slide. Try and sketch what you see in your books.”
Jayanthi asked me to help the children look through the microscope so that she could get the next set of slides ready.
Shalini said, “I saw some green round cells, something like a bean, which was moving, and something like a round cup with hair.” Everyone agreed with her.
I marked the picture to explain. “Paramecium is a single-celled organism like Amoeba; it is bean or slipper-shaped. The cup-shaped structure is Vorticella. Both are protozoans, meaning first-formed animals. They are Eukaryotes, which means they have proper nuclei in the cell. Both belong to the ciliates group, which means they have hair-like structures on the body, which helps in movement. Vorticella are called ‘epibionts’ as they live on the bodies of other animals, like mosquitoes, prawns, and tadpoles. They are not harmful to the host. It is a neutral relationship. And the chain-like and clumped forms you see are green algae,”
“I focused only on the algae on this next slide. It looks like a chain of beads,” Jayanthi said.
“Now let us move to the next microscope, one by one, please. Can you see these structures when you look through the microscope?” I showed a pencil sketch to the children.
“What are these? It looks like a whip,” Anand said.
“It looks like a horn on a brick,” Shalini said.
“These are hairs or trichomes on the fern leaf,” I replied.
“Oh! This causes itching. I remember now,” Anand replied as he looked through the microscope.
Jayanthi called us to the next table. “See, this is agar powder, we use it to prepare food for growing bacteria and fungi. From Agar, culture media is prepared and poured on a petri plate to help in the growth of bacterial and fungal colonies. This is an air-exposed plate. Here, you can see the growth of different bacterial and fungal colonies.”
“We know Agar Agar, it is a seaweed,” Rini said.
“Very good. It is from the same source, but this is laboratory grade,” Jayanthi patted Rini.
“Look at these specimens!” Rini pointed to a lemon and some sprouts that were rotting.
“Now, let us observe fungi. The green mold on the lemon is Penicillium. It is commonly found on citrus fruits. The black cottony growth on the sprouts is Rhizopus. The fungi life cycle involves spore production, either sexually or asexually. The spores then germinate and grow into mature fungi, which eventually form mycelium. This mycelium then forms the fruiting bodies that produce and disperse spores to start the new cycle,” Jayanthi explained.
“The fungi life cycle is similar to moss and fern life cycle, is it not? Earlier Nandini had explained that to us,” Sujatha said.
“We add certain specific stains so that the different fungi and bacteria can be easily identified,” Jayanthi said.
Jayanthi adjusted the specimen under the microscope and drew pictures on a white sheet. She marked the pictures to explain.
“These small round forms are conidiophores and the black round forms are sporangiospores. If all are spores, why the different terminology?” Anand asked.
“Conidia are borne singly or in chains on special branches called conidiophores. The sporangiospores, on the other hand, are contained within the sporangium. They are generally produced in large numbers. The slender tape-like structure below is mycelia,” Jayanthi replied.
Rini said, “We have seen fungi, but where are the bacteria? Can we see bacteria under the microscope?”
“Sure, wait for some time. I will get the specimen ready,” Jayanthi replied and went away to prepare the next few slides while we busied ourselves discussing what we had seen so far.
Suggested activities
- What are the different types of relationships you observe among organisms?
- Identify the bacterial and fungal infestations you observe in your kitchen.
References
https://www.nhm.ac.uk/discover/when-did-dinosaurs-live.html
https://jntbgri.res.in/gallery
The author is a botanist. She has been involved in teaching and research for more than 25 years. Currently, she is involved as a consultant for Intellectual Property Rights, for Karnataka State Council for Science and Technology, Bengaluru and is a visiting faculty member at RIWATCH, Roing, Arunachal Pradesh. She can be reached at nandinidholepat@gamil.com.
