Question

Distinguish between precystic stage and cystic stage of E. Histolytica.

Answer 1

The category B agent of bioterrorism, Entamoeba histolyticahas a two-stage life cycle: an infective cyst stage, and an invasive trophozoite stage. Due to our inability to effectively induce encystation in vitro, our knowledge about the cyst form remains limited. This also hampers our ability to develop cyst-specific diagnostic tools.

Aims

Three main aims were (i) to identify E. histolytica proteins in cyst samples, (ii) to enrich our knowledge about the cyst stage, and (iii) to identify candidate proteins to develop cyst-specific diagnostic tools.

Methods

Cysts were purified from the stool of infected individuals using Percoll (gradient) purification. A highly sensitive LC-MS/MS mass spectrometer (Orbitrap) was used to identify cyst proteins.

Results

A total of 417 non-redundant E. histolytica proteins were identified including 195 proteins that were never detected in trophozoite-derived proteomes or expressed sequence tag (EST) datasets, consistent with cyst specificity. Cyst-wall specific glycoproteins Jacob, Jessie and chitinase were positively identified. Antibodies produced against Jacob identified cysts in fecal specimens and have potential utility as a diagnostic reagent. Several protein kinases, small GTPase signaling molecules, DNA repair proteins, epigenetic regulators, and surface associated proteins were also identified. Proteins we identified are likely to be among the most abundant in excreted cysts, and therefore show promise as diagnostic targets.

Major Conclusions

The proteome data generated here are a first for naturally-occurring E. histolytica cysts, and they provide important insights into the infectious cyst form. Additionally, numerous unique candidate proteins were identified which will aid the development of new diagnostic tools for identification of E. histolytica cysts.

Answer 2

The life cycle of E. histolitica has two main stages with an intermediate stage.

They are

1. The trophozoite stage
2. The intermediate precystic stage
3. The cystic stage  

Explanation:

Entamoeba histolytica is a protozoan parasite that causes amoebic dysentary especially in developing countries. This pathogen also causes amoebic liver abcess.  

The life cycle of E. histolitica has two stages - trophozoite and cystic stages with an intermediate precystic stage.  

(The trophozoite stage is the most active growing and feeding stage which is characterized by its constantly changing shape due to many pseudopodia, but with single nucleus. )

The precystic stage

• Before the trophozoite becomes a cyst, it undergoes some changes in this pre-cystic stage.
• The size of the (single) nucleus decreases.
• The shape becomes more defined with a single blunt pseudopodium
• Feeding ceases.
• This is a non-infectious form.

The cystic stage

• The pre-cyst which contains a single nuclues undergoes 'encystations' in the lumen of the intestine.
• It becomes round in shape and non-motile (no pseudopodium).
• It starts producing a transparent protective cell wall made up of chitin.
• The nucleus undergoes division twice resulting in a tetra-nucleate cell.
• This is an infectious form which passes out though the faeces of the host.
• These cysts are capable of surviving outside for about 10 days.
• When food or water contaminated with these cysts  is consumed by a susceptible host, they enter the intestine where 'excystation' starts and the cysts transform to active trophozoites.

Going through the following link will be helpful.

Explain the structure and life cycle of Entamoeba Histolytica with the help of neat and labelled diagrams.

https://brainly.in/question/6545437