11/02

intro to plasmodium, cause of malaria

disease

malaria - disease

plasmodium spp. - microbe that causes the disease

very ancient

TB impacting humans for thousands of years (about 50 thousand)

prok vs. euk

bacteria that have nuclei - eukaryote

3 main branches

virus vs bacterium vs eukaryote

Plasmodium – has 14 chromosomes and 23 million base pairs

~5,300 genes

3 infection sites with plasmodium

RBC

mosquitos

liver

infection in 3 acts

tansition between mosquito and blood form:

Know this figure

This schematic shows almost everything

Merozoites – form that infects RBC – only thing that they do

- once infected, makes more of itself

- infected RBC breaks -> release baby merozoits + infect more RBCs

- once in a while , when merozoite in rbc -> instead of making more -> will go to bone marrow + form 1 of 2 gametocytes

-> gametocytes release back into blood +

- if mosquito take bloodmeal -> pick up gametocyte (must pick up opposite sex ones) -> fertilization process in mosquito make zygotes

-> zygotes in dev into oocyst - gives rise to sporozoite form of plasmodium

- sporozoites emerge from oocyst

- sporozoites -> transfer to another individual when mosquito bites them (SPOROZOITES ARE THE TRANSFER FROM MOSQUITO)

- sporozoites from mosquito travel blood -> (OCCUR EXCLUSIVELY/ONLY IN LIVER CELLS) liver -> infect liver cells (hepatocytes) – where sporozoite grows + change form back into merozoite (IN INFECTED LIVER CELLS)

- what leaves liver cells = MEROZOITES

- merozoites emerging liver cells = complete cycle -> start over -> infect RBC, etc.

KNOW WHAT ALL THE FORMS ARE

(bottom 1/3 of graph is inside the mosquito)

Mosquito – vector

- mosquito also where genetic shuffling occurs

merogony

• (biology) form of asexual reproduction whereby a parasititc protozoan replicates its own nucleus inside its host cells and then induces cell segmentation; schizogony
• (medicine) the development of part of an ovum after damage

merozoite form of plasmodium is VERY small

merogony - means when merozoite infect RBC when get inside

imaging of merozoite

invasion in fixed cells

imaging of merozoite invasion in fixed cells

• purified merozoites were fixed in the process of invasion to visualize invasion events
• they were examines at the point of initial binding to the RBC surface, midway, and after invasion was complete

merozoites invading, growing, and then getting out of the RBC

lyse + release progeny/baby merozoites

see pic

instead of making more merozoites, a merozoite can differentiate into a "sex cell", the gametocyte

stages of P. falciparum

• normal red cell
• trophozoite
• correspond to ring stage trophozoite
• schizonts
• mature macrogametocytes (female)
• mature microgametocytes (male)

Slides of what infected RBCs look like

Don’t need to know stage names

Can dev into either macro or micro gametocyte(male/female)

- instead of making more merozoites, CAN make gamtocytes

- random whether make male or female

plasmodium in the mosquito (anopheles spp.)

gametocytes taking up in blood

release sporozoite by mosquito into individual (about 2 weeks later)

process begin in gut/intestinal tract of mosquito

• if male and female both present - fuse and form zygote ->
• oozyte come out of gut -> make sporozoites -> migrate to salivary gland of mosquito -> transfer when bite next victim

mosquito to hepatocyte: sporozoite

Sporozoites about 20x or more bigger than merozoite

sexual reproduction occurring in plasmodium is EXACTLY the same as in animals and plants

animals: egg (n - halpoid) + sperm (n - haploid) -> zygote (nn - diploid)

plasmodium: macrogamete (n - haploid) + microgamete (n - haploid) -> zygote (nn - diploid)'

Macro gamete – haploid – fuse w/ opposite sex gamete -> zygote = diploid cell

Occurs in circled stage

= MEIOSIS

Oocyst – in tissue of mosquito – diploid

-> Forms sporozoites (haploid)

-> We get infected w/ haploid cells

-> Whole process = meiosis (does a lot of gene shuffling)