CUBE ChatShaala: 22nd Nov 2020
The discussion was juggling between two models; Zebrafish and Earthworms alike as both were connected under the common field of immunology.
CUBist Ishita (from Jorhat, Assam) is interested in working on Zebrafish as her model organism to address questions on Immunology.
The introductory question was that how will immunology be studied on zebrafish?
But before that, how do we maintain them? The discussions in the CUBE ChatShaala of Nov 3rd week has highlighted the importance of maintaining model organisms properly without leaving updates!
Do zebrafish alongwith other models have an immune system?
If not, then how will they fight with a disease-causing pathogen(s)/infectious agent(s)?
In human blood, what type of cells are present and which are the immune cells? The above slide is self-explanatory!
This was discussed with respect to earthworms a month ago and now w.r.t. zebrafish– How will we go about visualising the immune cells namely Monocytes, Lymphocytes, Neutrophils, Eosinophils and Basophils? If we mean to study them!
Staining! The Wright-Giemsa stain is generally used to stain the blood cells in laboratories. If we go about measuring the size of these cells, how small/big are they for the naked eyes?
How are the cells getting stained and appearing to be coloured when visualised?
What exactly is getting stained?
The Wright-Giemsa stain is a mixture of acidic, basic as well as neutral stains (Eosin, methylene blue, azure B respectively) that stain the components of the cytoplasm of these cells.
We confirmed the presence of immune system/cells through references!
i) ORIGINAL RESEARCH ARTICLE
Front. Immunol., 18 June 2019 | https://doi.org/10.3389/fimmu.2019.01277
Developmental and Immune Role of a Novel Multiple Cysteine Cluster TLR From Eisenia andrei Earthworms
Drosophila Hemopoiesis and Cellular Immunity
Michael J. Williams
J Immunol April 15, 2007, 178 (8) https://doi.org/10.4049/jimmunol.178.8.4711 Abstract
In Drosophila melanogaster larvae, three classes of circulating cellular immune surveillance cells (hemocytes) can be identified: plasmatocytes, crystal cells, and lamellocytes. Plasmatocytes are professional phagocytes most similar to the mammalian monocyte/macrophage
In earthworms, three types of PRRs have been described so far—Toll-like receptor EaTLR, coelomic cytolytic protein CCF, and lipopolysaccharide-binding protein EaLBI/BPI (2–4). TLRs are conserved membrane pattern recognition receptors that detect microbes on the basis of pathogen-associated molecular patterns (PAMPs) (5). The first member of this family, named Toll, was originally identified as a molecule responsible for the embryonic dorsoventral development of the fruit fly Drosophila melanogaster (6),https://www.frontiersin.org/articles/10.3389/fimmu.2019.01277/full
When asked how will we study immune cells in zebrafish, Ishita said, we can study them via embryo(s) of zebrafish. "As early as one day after fertilization (dpf), zebrafish embryos display phagocytic activity towards microbial infections  and are able to mount an innate immune response with a transcriptional signature that resembles responses in mammalian or cell culture systems .Jul 1, 2012"
How can we study immune cells in zebrafish embryo? Will the embryo have all the immune cells that are to be studied?
Oh! Which type of immune cells are we aiming at? BCells? TCells?
Won’t it be easier if we study them in zebrafish itself? I mean, if we look at the availability and approachability, zebrafish will be easily available. On the contrary, the embryo may require microscopy to work upon!
A quirky question from my side; what is the cell-stage of the embryo? and will the embryo get stained too!?
For a short while, we discussed the difference between innate immunity and acquired immunity. We heard that, "innate immunity provides a quick response to eliminate the antigen whereas acquired immunity may take time to act and generate an immune response."
How do we define an antigen? Does this mean that in case of innate immunity, our body is already prepared for eliminating the antigen as like a preloaded gun ready to fire!!?
This is a context to understand how our body interacts/may interact with SARS-CoV2 and other such viruses?
Is there a need for a vaccine for COVID19 when we discuss improving immunity among masses; herd immunity?
Let us educate/re-educate ourselves by discussing such exciting things!
How difficult/easy is it to find earthworms in our neighbourhood? Aren’t they regular customers of the soil?
The answer to the first question (when talking about any model organism/animal) lies in their natural habitat!
If we talk of earthworm cup cultures, how do we come to know that the earthworms are healthy and living happily?
We often see body-coloured (earthworm’s body) materials; faeces in the cup cultures. If they are feeding, they would be excreting as well. How about applying the same logic in finding earthworms in the soil?
If we look below moist/recently watered plant pots in a garden/lawn/open area, there are chances that earthworms can be found there. And looking for earthworm faeces will show the presence of them in that area.
Earthworm cup cultures are a context for us to study Biochemistry!
How is tissue paper acting as a nutrient source for the earthworms?
Let me tell you, the word nutrient is a misnomer in many ways unless defined in each case!
Tissue paper is the major source of carbohydrate in the form of Cellulose (a polysaccharide).
How/why do we call cellulose a polysaccharide?
If we go by the hierarchy; Monosaccharides–>Disaccharides–>Oligosaccharides–>Polysaccharides are what we get.
Defining each of them with the help of examples will do good!
"Cellulose consists of long chains of d-glucose units linked by β (1 → 4) glycosidic bonds (shaded), with alternating units rotated 180° with respect to their neighbor. This means that the repeating unit is cellobiose, not glucose; also, the polymer forms a straight chain."
This means cellulose is broken down/hydrolysed by enzymes (which? I know it😏) to give monosaccharides that are processed further to aid energy in the form of ATP! And what else? Just energy? Let’s find out!
All the slides of the whiteboard are self-explanatory😅!