Transcript Heterotrophic Protists II

Kingdom Protista
Hetetotrophic 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 sphaerica
with wood fibers
bacteria
found on
T. sphaerica
surface
African Sleeping Sickness
caused 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.
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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.
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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.
lesions
caused by
the 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)
RBCs with
merozoites
3) At regular intervals, the merozoites burst out of
the RBCs and release toxins in the blood.
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 mosquitoborne 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 malariacarrying 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)