Transcript Document

Lecture 2. Classification of
Living things. Prokaryotes,
Eukaryotes, Viruses
Myandina Galina Ivanovna,
Ph.D., Dr. Sc., professor
20.07.2015
Taxonomy is the science of identifying,
classifying and naming organisms
The Diversity of Living
Systems
The bases of scientific classification
• structural similarity and morphological
features
• cellular organization
• biochemical similarity is based on comparing
of the proteins and DNA structure.
• genetic similarity
• embryological evidence
Binomial nomenclature
• K. Linnaeus separated living
things first into very large
groups called kingdoms,
• next he divided each kingdom
into phyla (phylum),
• and each phylum is divided into
classes.
• A class contains many orders.
• A division of order is a family.
• A family contains related
genera.
• A genus is composed one or
more species.
Classification of man
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The Kingdom: Animalia (includes all animals)
The Phylum: Chordata (have back bones)
The Subphylum: Vertebrata
The Class: Mammalia (the animals having
mammary glands)
The Order: Primates
The Family: Hominidae
The Genus: Homo
The Species: Sapiens
Taxonomy is the science of identifying,
classifying and naming organisms
• The taxonomy is able to infer the
evolutionary relationships among
species
Phylogenetic tree
• phylogenetic tree
is a visual model
of the inferred
evolutionary
relationships
among organisms
All the living things are divided in two
groups:
• Prokaryota (Eubacteria, Arhaebacteria)
• Eukaryota (Protista, Planatae, Animalia and
Fungi)
Kingdom Protista (the protozoa)
• Phylum Sarcomasyigophora
• Phylum Apicomplexa
• Phylum Ciliophora (the ciliates)
Kingdom Animalia
• Phylum Plathelminthes
• Phylum Nemathelminthes
• Phylum Arthropoda
Five-kingdom system
Kingdom
Cell type
Cell number
Major mode of
nutrition
Assimilation’s
characteristics
Monera
Prokaryotic
Unicellular
Absorb or
photosynthesiz
e
Autotrophic or
heterotrophic
Protista
Eukaryotic
Unicellular
Absorb, ingest
or
photosynthesiz
e
Autotrophic or
heterotrophic
Plantae
Eukaryotic
Multicellular
Photosynthesiz
e
Only
autotrophic
Fungi
Eukaryotic
Most
multicellular
Absorb
Heterotrophic
Animalia
Eukaryotic
Multicellular
Ingest
Heterotrophic
Comparing viruses and cells
Characteristics
Virus
Cell
Structural
parts
.
Protein capsid,
nucleic acid
core
Genetic material
DNA or RNA
Reproduction
Requires a host
cell
By mitosis and
meiosis
Crystallization
Yes
No
Nucleus,
cytoplasm,
organelles,
membrane
only DNA
INTESTINAL AND
UROGENITAL PROTOZOA
Phylum Sarcomasyigophora (the protozoa)
• Subphylum Sarcodina (the amoebae)
• Entamoeba histolytica (amoebiasis, amoebic dysentery)
• Subphylum Mastigophora (the flagellates)
• Class Zoomastigophora
• Trichomonas vaginalis (trichomoniasis)
• Trichomonas intestinalis hominis
• Giardia lamblia (giardiasis, lamblios)
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Order Kinetoplastida
• Trypanosoma brucei gambiense
• Trypanosoma brucei rhodesiense (African trypanosomiasis)
• Trypanosoma cruzi (Chagas’ disease)
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Leishmania tropica (cutaniosis leishmaniasis)
Leishmania donovani (visceral leishmaniasis)
Leishmania brasiliensis (mucocutaniosis leishmaniasis)
The protozoa, cont.
Phylum Apicomplexa
Class Sporozoea
• Plasmodium spp. (malaria)
• Toxoplasma gondii (toxoplasmosis)
Phylum Ciliophora (the ciliates)
• Class Litostomatea
• Balantidium coli (balantidiasis)
Phylum Sarcomasyigophora (the protozoa)
Entamoeba histolytica
Leishmania tropica
Giardia lamblia
Trypanosoma brucei gambiense
Intestinal and luminal protozoa
significant to human health include
• Entamoeba histolytica (Amebae)
• Balantidium coli (Ciliates)
• Giardia lamblia and Trichomonas vaginalis
(Flagellates)
TEACHING OBJECTIVES
• Epidemiology, morbidity and mortality
Morphology of the organism
Life cycle, hosts and vectors
Disease, symptoms, pathogenesis and
site
Diagnosis
Prevention and control
AMEBIASIS (amebic dysentery, amebic
hepatitis)
• 0.5 to 50% of the population world wide
harbors Entamoeba histolytica causes
amebic dysentery
• Humans are the principal host
• Infection is associated with poor hygiene
• Amebic dysentery is spread by fecal
contamination of food and water
Trophozoites of Entamoeba histolytica
• The trophozoites (forma
magna) are elongated (up
to 60 µm in length), they
tend to be in diarrheal
stool
• Two diagnostic
characteristics are seen
here: the nuclei show a
centrally placed
karyosome with a
uniformly distributed
peripheral chromatin
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Life cycle of Entamoeba
histolytica
Symptoms
• Acute: Frequent dysentery with necrotic
mucosa and abdominal pain
• Trophozoites are found in stool
• Chronic: Recurrent episodes of dysentery
with blood and mucus in the feces
• Cysts are found in the stool
• The organism may invade the liver, lung and
brain where it produces abscesses that
result in liver dysfunction, pneumonitis, and
encephalitis
Diagnosis
• Symptoms, history and epidemiology
are the keys to diagnosis
• In the laboratory: finding cysts in the
stool
GIARDIASIS (lambliasis)
• Giardia lamblia (a flagellate) is the most
common cause of water-borne disease
• It is associated with:
• breakdown of water purification systems,
• drinking from contaminated streams,
• travel to endemic areas (Russia, India, Rocky
Mountains, etc.) and day care centers
Morphology
• Trophozoite: Giardia is a half
pear-shaped organism with 8
flagella and 2 axostyles
arranged in a bilateral
symmetry.
• There are two anteriorly
located large suction discs.
• The cytoplasm contains two
nuclei and two parabasal
bodies
• Cyst: Giardia cysts are
ellipsoidal cells with a smooth
well-defined wall. The
cytoplasm contains four nuclei
and many of the structures
seen in the trophozoite
Life cycle
• Infection occurs by
ingestion of cysts,
• trophozoites colonize the
upper small intestine
• The cysts are passed in
the stool
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Man is the primary host
Symptoms
• abdominal distension
• nausea and foul-smelling bulky, explosive,
often watery, diarrhea
• The stool contains excessive lipids
• The more chronic stage is associated with
vitamin B12 malabsorption
• malabsorption of nutrients
Diagnosis
• Giardia caused dysentery is distinct from
other dysenteries due to lack of mucus
and blood in the stool
• lack of high fever
• Cysts in the stool and trophs in the
duodenum can be identified
microscopically
Balantidium coli
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This is a parasite primarily of
cows, pigs and horses. The
organism is a large ciliate with a
macro- and a micro-nucleus
The infection occurs mostly in
farm workers and other rural
dwellers by ingestion of cysts
in fecal material of farm
animals.
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Cysts are the parasite stage
responsible for transmission of
balantidiasis
The host acquires the cyst through
ingestion of contaminated food or
water
excystation occurs in the small
intestine, and the trophozoites
colonize the large intestine
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Balantidium coli
• zoonotic protozoan intestinal infections with some health
significance
• Cysts are the parasite stage responsible for transmission
of balantidiasis
• The host most often acquires the cyst through ingestion
of contaminated food or water Following ingestion,
excystation occurs in the small intestine, and the
trophozoites colonize the large intestine . The
trophozoites reside in the lumen of the large intestine of
humans and animals, where they replicate by binary
fission, during which conjugation may occur
. Trophozoites undergo encystation to produce infective
cysts . Some trophozoites invade the wall of the colon
and multiply. Some return to lumen and
disintegrate. Mature cysts are passed with feces
• Symptoms and pathogenesis of
balantidiasis are similar to those seen
in entamebiasis
• liver, lung and brain abscesses are not
seen
• Diagnosis:
• Detection the cyst in stool
TRICHOMONIASIS
• T. vaginalis colonizes the
vagina of women and the
urethra of men.
• Infection occurs primarily
via sexual contact, nonvenereal infections are
possible.
• The organism does not
encyst and divides by
binary fission.
• There is no non-human
reservoir
Symptoms
• The organism causes contact-dependent damage
to the epithelium of the infected organ
Diagnosis
• Clinical suspicion may be confirmed by finding
the organism in stained smears of vaginal
discharge
Summary
Organism
Entameba
histolytica
Giardia lamblia
Balantidium coli
Trichomonas
vaginalis
Transmission
Oro-fecal
Symptoms
Dysentery with
blood and
necrotic
tissue.
Chronic:
abscesses
Diagnosis
Treatment
Stool: cysts with 1- GI: Iodoquinol or
4 nuclei and/or Metronidazole
trophs.
Abscess:
Metronidazole
Trophs in aspirate.
Oro-fecal
Fowl-smelling,
bulky
diarrhea;
blood or
necrotic tissue
rare.
Stool: typical old
man giardia
troph and/or
cyst.
Iodoquinol or
Metronidazole.
Oro-fecal;
zoonotic
Dysentery with
blood and
necrotic tissue
but no
abscesses.
Stool: ciliated
trophs and/or
cysts.
Iodoquinol or
Metronidazole.
Sexual
Vaginitis;
occasional
urethritis/pros
tatitis.
Flagellate in
vaginal (or
urethral)
smear.
Mebendazole;
vingar
douche;
steroids