Showing posts with label replication. Show all posts
Showing posts with label replication. Show all posts

Friday, 1 January 2016

Who is the guilty of this vegetable crime?

There is no other culpable than Cucumovirus, which can be identified if looking to it  you are able to diferenciate a non-enveloped, spherical virion of about 29 nanometers in diameter, which has a T=3 icosahedral symmetry composed of 180 coat proteins: 12 pentamers and 20 hexamers.

Image 2.1. Picture about the real 
morfology of CMV


How this murderer is formed of?

It is not an easy question, and there must have being other researchs before answering this issue. His structure is formed of a segmented tripartite linear RNA composed of RNA1, RNA2 and RNA3. Each genomic segment is 3' tRNA-like structure and a 5' cap.

Image 2.2. Position of dierent RNA that compose the 
segmented tripartite linear virus RNA


This Cucumovirus expresses himself by using the RNA as a messager RNAs. Then, RNA1 and RNA2 encode proteins 1a and 2a, involved in the genome replication and internal transcription of sgRNA4 from the negative copy of RNA3. HRNA3 is translated into a movement protein, while sgRNA4 it translates to a capsid one. Apart from this, ORF2b, present at RNA2, encodes a viral supressor of RNA silencing.

How does it commit the crimes?

When the expression is done, virus expresses the protein 1st and 2nd to produce replication proteins, as I have mentioned before, on the viral factory and after it transcribes/replicates providing new ssRNA genomic (new viruses).
Everithing continues translating RNA4 that produces the capsid that envolves the ssRNA genome, and assemblying this virus particles.


Image 2.3. Picture of diferent viral factories for viruses

Finally, it is the turn of the viral movement protein, that triggers the information of tubular structures that mediate viron cell-to-cell transfer via a tubule-guided mechanism.

Thursday, 31 December 2015

How the murderer achieves to penetrate a really complex security system?

I am gonna explain the mechanism of commiting murder used by this relentless virus. 


Image 4.1. Insects being 
vectors of the virus

First of all, this murderer has to be transmitted from somewhere, and this Bromoviridae family virus, arrives to the host in two possible ways. The first, by a mechanical inoculation in plant by an insect, and the second is even simple, staying in contact one plant with another. 


Image 4.2. Vegetable cells that
shows easily the tonoplast


After have penetrated on it, Cucumovirus has succeed one of his objectives necessaries to commit the crime: entering to a vegetable cell. When staying inside it starts to uncoat, what implicates to release the viral nucleic acids from the capsid, liberating the viral genomic RNA into the cytoplasm, contained inside the virus cell sorrounded by the capsid; causing the expression of the first and second protein, what produces the recplication proteins, responsible for synthetising the RNA strands, in a viral factory, that can be different types of organelles, in concrete, the accomplice of giving home to this criminal is the vacuoles membrane or also called tonolpast. 

Image 4.3. Electronic micrscope
photo of a bascular bundle cells
And the crime starts! 
It produces a transcribement of the complete RNA genome, providing new viral RNA genomes in order to multiply the CMV to the whole plant, but it can really go somewhere alone? No, there must be something controlling it and this is not other than the capsid, a organelle that mantains everything to it position, so can, now, moves. Finally the viral movement protein triggers the formation of tubular structures called plasmodesmatas what allows the murderer to move from one host to the other next to it.


Image 4.4. Picture displaying the transport plasmodesmata system

But "when more you have, more you want", hence the Cucumovirus not happy by infecting mature cells, it transports cell-to-cell, traspassing different cells as Sclerenchyma, Collechyma, Parenchyma and Xyle, aiming to arrive to the phloem so can be transported easily to the green shots, his ambitious objective.

Image 4.5. Explicative picture of bascular bundle cells