Transcript Plasmodium/Human symbiosis

Plasmodium/Human symbiosis
Life Cycle and Importance
What is Plasmodium?
Plasmodium is an apicomplexan (previously called
sporozoans) that causes malaria in humans. An
apicomplexan is a protist that disseminates small
infectious cells called sporozoites., and has organelles
that are specialized for penetrating host cells and
tissues, which are called apical complexes.
The Plasmodium Life Cycle
 http://highered.mcgraw-hill.com/olc/dl/120090/bio44.swf
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http://www.youtube.com/watch?v=s_nOgu8OnZA&NR=1&feature=fvwp
The Life Cycle of Plasmodium Continued
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A female anopheles mosquito bites a person that has malaria, and picks up plasmodium
gametocytes
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Gametes form from the male and female gametocytes and fertilization occurs in the digestive
tract of the mosquito.
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An oocyst develops from zygote in wall of mosquito’s gut. Sporozoites develop in the oocyst
and migrate to mosquito’s salivary gland.
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Mosquito bites another person, releasing the plasmodium sporozoites into the bloostream,
where they then travel to and enter the victim’s liver cells. This way, the small cells can avoid
the lymphocytes (blood cells that identify invasions of foreign bodies) in the blood stream.
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Several days pass, and the sporozoites undergo multiple divisions to become merozoites. The
merozoites then use their apical complexes to penetrate the red blood cell and enter it.
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The merozoites then grow and divide asexually, and repeatedly break out of the red blood
cells in intervals of 48 or 72 hours, which triggers the response of the immune system, and
subsequently the symptoms of the immune system response to malaria show; periodic chills
and fever.
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Other merozoites infect new red blood cells.
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Some merozoites divide sexually to form gametocytes, which can then be picked up by the
next anopheles mosquito to bite the infected person, and the cycle starts over again.
Trivia and Current Research
• A gene has recently been identified that may be the cause of plasmodium resisitance to
chloroquine; an important antimalarial drug.
This discovery may pave the way for methods of preventing drug resistance in
plasmodium.
•Bill Gates has recently told the BBC that a malaria vaccine is in “phase three” of its
development, in other words, it has begun the trial phase. He added that “a fully effective
vaccine will take five to ten years.”
• BBC news: “Gates says malaria vaccine could ready in three years”
http://news.bbc.co.uk/2/hi/health/8479986.stm
Impact of Malaria
According to the World Health Report and the CDC, Malaria kills 853,000 children
under 5 per year.
Leading Causes of Death in Children Under Five Years of Age, Estimates for 2000-2003
(Source: World Health Organization, The World Health Report 2005)
Numbers
(thousands per
year)
% of all
deaths
Rank
Cause
1
Neonatal causes
3,910
37
2
Acute respiratory infections
2,027
19
3
Diarrheal diseases
1,762
17
4
Malaria
853
8
5
Measles
395
4
6
HIV/AIDS
321
3
7
Injuries
305
3
1,022
10
10,596
100.0
Other causes
Total
Source:
http://www.cdc.gov/malaria/impact/i
ndex.htm
Review Questions and Additional
Information
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What is an Apicomplexan?
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Where do the sporozoites go after being transferred into the blood stream of the
victim?
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What specialized organelle is responsible for penetrating host cells and tissues?
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What do sporozoites become after multiple divsions in the liver?
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Where do these cells go, and how?
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What part of the mosquito do the sporozoites travel to?
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Where does the fertilization of gametocytes take place?
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Is plasmodium eukaryotic or prokaryotic?
Additional Information on Plasmodium and
Apicomplexans
Page 527- Description of Apicomplexans
Page 528- Life Cycle of Plasmodium and Description
Answers To Review Questions
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An Apicomplexan is a protist that has specialized organelles
made for penetrating host cells and tissues
The liver
Apical complex
Merozoites
Into the red blood cells, by penetrating the cell with the apical
complex
The salivary glands
The wall of the mosquito’s digestive tract
Prokaryotic
Sources Cited
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McGraw Hill: http://highered.mcgrawhill.com/olc/dl/120090/bio44.swf
“The Impact of Malaria, a Leading Cause of Death
Worldwide.”The Department of Health and Human
Services Center for Disease Control
Biology. Campbell, Neil; Reece, Jane; Mitchell, Lawrence.
527-528
Animal Planet TV, “Monsters Inside Me: Living With the Enemy.”
http://www.youtube.com/watch?v=s_nOgu8OnZA&NR=
1&feature=fvwp