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Kingdom ProtistaHetetotrophic Protists II:
Zooflagellates & Sporozoans
D) Zooflagellates: Phylum Sarcomastigophora
1) Movement: Flagellum
The Termite, the zooflagellate & the bacteria.
• Although termites are famous for their ability to eat wood, causing damage to wooden structures and recycling cellulose in the soil, they are unable to digest the wood that they eat. To break down the cellulose, termites enlist the help of a variety of microorganisms.
Protozoans such a Trichonympha sphaerica to digest cellulose is an example of endosymbiosis, a symbiotic relationship with an organism that lives inside the body of the host organism (in this case, within the hindgut of the termite).
Trichonympha sphaerica itself is unable to digest cellulose with out
the aid of bacteria that live within its body; in other words, the protozoan has its own endosymbionts.
These ciliates are covered by precise rows consisting of thousands of bacteria, either rods or spirochetes.
If these bacteria are killed, the protozoan in unable to move. Evidently, the protozoan does not use its cilia to move; instead, the rows of bacteria move the protozoan like rows oarsmen in a boat.
• The bacteria beat their flagella to create coordinated waves along all these rows of filaments, thus propelling the protozoan.
• An important question remains: Do the bacteria detect a food source and move the protozoan toward it, or does the protozoan force the bacteria to respond to its commands?
Trichonympha sphaericawith wood fibers
bacteria found onT. sphaerica surface
African Sleeping Sicknesscaused by a zooflagellate
a) Trypanosoma gambiense can cause African
Sleeping Sickness (Trypanosomiasis)
It is transmitted by the tsetse fly. It is
characterized by increasing fever, lethargy,
mental deterioration, and coma.
Sleeping sickness is blamed for some 25,000 deaths in Africa each year. the disease (along with a similar disease called nagana) annually kills 3 million cattle.
In the 1980s, the tsetse fly was fought with dangerous insecticides
like DDT, long banned in the United States for its harmful
effects on birds and other animals. Researchers in Zimbabwe have
been experimenting with luring the flies to cloth sheets coated with chemicals produced by cows, as
well as insecticides designed to kill the flies. This has been successful
in Zambia, South Africa and the Ivory Coast. (Discover 2002)
b) Another Disease caused by Trypanosoma is Chagas’ Disease (Typanosoma cruzi)
Transmitted by the “kissing bug”
The patient suffers from fever
& severe heart damage. It can
also cause eyelid & facial
swelling called “chagoma.”
Usually in South
America & Mexico
c) A zooflagellate called Giardia lamblia causes giardiasis – an illness that causes severe diarrhea & intestinal cramps.
It is transmitted when animals with the organism
their feces, contaminate water supplies.The disease is usually not fatal. It usually occurs in Africa, but thousands of cases occur in the U.S.
d) A disease called leishmaniasis, a blood disease, afflicts millions in Africa, Asia and Latin America. ( 12 million infected worldwide)
It is transmitted by the sand flea. (The zooflagellate Leishmania donovani.) It can
cause disfiguring skin sores, fever, chills, weight loss, anemia, and can be fatal.
lesionscaused bythe disease
Although some species of Leishmania produce no more than pimples, others are lethal: in the southern Sudan alone, for instance, leishmaniasis has killed as many as 100,000 people (between the mid 1980s and the mid 1990s) as villagers fleeing a civil war had taken refuge in forests that are sand flea breeding grounds.
Sand Flea Orchestia agilis
Less than 1/8 inch long shrimp-like creatures. This is not an insect
but an amphipod(crustacean).
A species of Leishmania found in the Amazon basin had been known to eat away the entire face of its victim, until he starves to death or suffocates, sometimes many years after the initial infection. In part because leishmaniasis takes so many different forms researchers have been unable to develop an effective vaccine against it.
E) Phylum Apicomplexa: No Form of Locomotion (sporozoans)
a) Toxoplasma gondii – causes toxoplasmosis
It is dangerous to newborns or a developing fetus. Some adults become seriously ill with flu like symptoms. It is transmitted by birds, rodents and domestic cats.
b) Plasmodium – causes malaria . It is characterized by severe chills, fever, sweating, fatigue, and great thirst. Victims die of kidney failure, anemia, or brain damage. It is carried by the Anopheles mosquito.
Malaria is estimated to kill more than 600,000 people every year, mostly in Africa.
Four species of Plasmodium can infect humans. All have life cycles that involve the Anopheles mosquito which transmits the protozoan to humans while feeding.
Why does a mosquito need human blood?
The female mosquito lays 30-150 eggs every 2-3 days. Human blood is needed to nourish these eggs and Anopheles shows the most regular cycles of blood feeding and egg laying.
By using personal protective measures against mosquito bites, like using mosquito nets, one can deny the blood meal and hence help in mosquito control.
Anopheles mosquitoes enter the house between 5 p.m. and 9.30 p.m. and again in early hours of morning. They start biting by late evening and the peak of biting activity is at midnight and early hours of morning. Also protect yourself against the bites in the evenings and early mornings by wearing garments that cover the body as much as possible and at bedtime, by using mosquito nets without fail.
How far do the mosquitoes fly? Mosquitoes can fly up to several kilometers! And they can
reach far off places by taking shelter in motor vehicles, ships and aircraft.
How long do they live? The average life span of a mosquito is 2-3 weeks. It can be
longer in ideal living conditions.
Where do they lay eggs?
Anopheles mosquitoes breed in natural water collections. Therefore, breeding increases dramatically in the rainy season when water collects in bottles, tins, tender coconut shells, buckets, tires etc., that are thrown out in the open and these provide ample breeding ground.
Malaria Cycle: 1) Sporozoites enter the blood. They travel to the liver. They repeatedly divide.
2) New spores called merozoites emerge and infect red blood cells. (They reproduce asexually)
3) At regular intervals, the merozoites burst out of the RBCs and release toxins in the blood.
RBCs with merozoites
Merozoites Bursting from RBCs
4) The merozoites infect other cells & reproduce asexually. This may happen many times.
5) Some merozoites develop into gametocytes. Mosquitoes become infected with them upon biting infected malaria sufferers.
6) In the mosquito’s digestive tract, the gametocytes join to form zygotes
7) The nucleus of a zygote divides and produces more sporozoites, which burst out of the body cavity and travel to the mosquito’s salivary glands, ready to infect the next victim.
Your smelly feet might save lives by building better malaria traps
• Scientists researching the deadly mosquito-borne disease malaria have made an interesting discovery: Mosquitoes carrying malaria parasites were three times more likely to be drawn to the odors from a dirty sock.
• Scientists hope to use the findings to develop more efficient traps that target malaria-carrying mosquitoes only. MSN.com 6/5/13
• Using traps that only target malaria mosquitoes could result in fewer mosquitoes becoming resistant to the insecticides used to kill them. And it would likely be difficult for insects to evade the traps based on their sense of smell, scientists say. (AP 6/5/13)
