(6) MICROBIO: Characterization and Classification of Eukaryotes

protozoa

- they share all these characteristics

a. eukaryotic

b. unicellular

c. lack cell walls

d. free-living; parasitic

e. 2-20,000 micrometer

- distributed in moist environment

trophozoite and cysts

- pleomorphic protozoa forms

trophozoite

- form of pleomorphic protozoa

- motile, feeding stage, diagnostic stage

cysts

- form of pleomorphic protozoa

- dormant, resting stage, infective stage, with low metabolic rate

chemoheterotrophic

- nutrition of protozoa

- obtain nutrients by phagocytizing bacteria, decaying organic matter, other protozoa, or the tissues of the host

- a few absorb nutrients from the surrounding water

photoautotrophic

- nutrition of protozoa

- produce their own food using light energy through photosynthesis

asexual and sexual

- types of reproduction of protozoans

binary fission

- example of asexual reproduction for protozoans

- longitudinal for flagellated

- transverse for ciliated

conjugation

- example of sexual reproduction of binary fission

- Paramecium reproduces through this method

Sarcodina (pseudopodia), Mastigophora (flagella), Ciliophora (cilia), Sporozoa (nonmotile)

- classifications of protozoa

- based on their locomotory structures (before) and based on nucleotide sequencing

Mastigophora (flagella)

- this largest group of protozoans

Sporozoa (nonmotile)

- this group of protozoans are all pathogenic to humans

alveolates, amoebae, euglenozoa, diplomonads, parabasala

- new/modern classification of protozoa

alveolates

- protozoa

- with small membrane-bound cavities called alvioli

- share at least one characteristic; tubular mitochondrial cristae

- ex. ciliates, apicomplexans, dinoflagellates

ciliates

- Balantidium, Paramecium, Stentor, Vorticella, Didinium

- under Alveolates

- have cilia by which they either move themselves or move water past their cell structures

Apicomplexans

- Babesia, Plasmodium, Toxoplasma, Crytosporidium

- under Alveolates

- all pathogens of animals

- the name of this group refers to the complex of special intracellular organelles, located at the apices of the infective stages of these microbes, that enable them to penetrate the host cells

Dinoflagellates

- Gymnodinium, Gonyaulax, Pfiesteria

- under Alveolates

- like many plants and algae, their food reserves are starch and oil, and their cells are often strengthened by internal plates of cellulose

- historically classified as algae because of their plant-like features, taxonomist today note their 18s rRNA sequence and the presence of alvioli indicate they are more closely related to ciliates and apicomplexans than they are to either plants or algae

- most of them are bioluminescent and photoautotrophic

- ex. Peridinium

red tide (red pigment)

- 50,000 cells/ml

- a neurotoxin (0.5mg)

- e.g. Gymnodinium and Gonyaulax

- ingestion of shell fish (have planktonic dinoflagellates)

PEAS (Possible Estuary-Associated Syndrome)

- Pfiesteria, another toxin (Lois Pfiester)

- handling infected fish; breath air laden with the microbes

- may cause memory loss, confusion, headache, respiratory difficulties, skin rash, muscle cramps, diarrhea, nausea, and vomiting

Amoebae

- classification of protozoa

- Foraminifera, Radiolarians, Free-living types, Parasitic types

(Cercozoa) Foraminifera

- under Amoebae

- has a porous shell composed of calcium carbonate arranged on an organic matrix in a snail like manner

- pseudopodia extend through the holes in the shell

- lived attached to sand grains on the ocean floor

- mostly microscopic, though scientist have discovered species several cm in diameter

Radiolaria

- under Amoebae

- thread-like pseudopodia, have ornate shells of silica

- live in marine water as part of the plankton

- the dead bodies of these settle at the bottom of the ocean where they form ooze that is hundreds of meters thick in some locations

Amoebozoa

- Amoebae that are either free living type, or parasitic type

- have a lobed shaped pseudopodia and no shells

slime molds

- formerly considered another group of amoebozoa- to be fungi, but the lobe-shaped pseudopodia by which they feed and move as well as their nucleotide sequences show that they are amoebozoa

- differ from fungi in two main ways:

a. they lack cell walls, more closely resembling amoebae in this regard

b. they are phagocytic rather than absorptive in their nutrition

- they are important to humans primarily as excellent laboratory systems for the study of developmental and molecular biology

Plasmodial (acellular) Slime Molds

- exist as streaming, coenocytic, colorful filaments of cytoplasm that creep as amoebae through forest litter, feeding by phagocytizing debris and bacteria

- e.g. Physarum

Cellular Slime Molds (Dictyostelium)

- exist as individual haploid myxamoebae that phagocytize bacteria, yeast, dung, and decaying vegetation

Euglenozoa

- classification of protozoa

- part of the reason that taxonomist established the Kingdom Protista in the 1960s was to create a "dumping ground" for eukaryotic microbes that share certain characteristics of both plants and animals

- most recently, based on similar 18s rRNA sequences, the presence of mitochondria with disc-shaped cristae, some taxonomist have created a new taxon

Kingdom Euglenozoa

- new taxon that include euglenids and some flagellated protozoa called kinetoplastids

Euglenids

- under Euglenozoa

- photoautotrophic, unicellular microbes with chloroplasts containing light absorbing pigments - chlorophyll a and b and carotene

- it is for this reason that botanist historically classified them in the Kingdom Plantae

- one reason for not including them with plants is that they store food as a unique polysaccharide called paramylon instead of starch

- similar to animals in that they lack cell walls, have flagella, are chemoheterotrophic phagocytes (in the dark) and move by using their flagella as well as by squirming movement which is similar to amoeboid movement but does not involve pseudopodia

- has flexible, proteinacious, helical pellicle that underlines its cytoplasmic membrane and helps maintain its shape

- typically has a "red eye", which plays a role in positive phototaxis

Kinetoplastids (Trypanosoma and Leishmania

- under Euglenozoa

- have a single large mitochondrion that contains a unique region of mitochondrial DNA called kinetoplast

- they live within animal, and some are pathogenic

paramylon

- euglenids have this while plants have starch

Diplomonads (Giardia, Microsporidia/Nosema)

- classification of Protozoa

- lacks mitochondria, golgi apparatus, and peroxisomes

- biologists once thought these organisms were descended from ancient eukaryotes that had not yet phagocytized the prokaryotic ancestors of mitochondria

- geneticist have recently discovered rudimentary mitosomes in the cytoplasm and mitochondrial genes in the nuclear chromosomes, a finding that suggests that they might be descended from typical eukaryotes that somehow lost their organelles

- ex. Giardia, Microsporidia (Nosema)

Parabasala

- classification of protozoa

- lack mitochondria, but each has a single nucleus and a parabasal body, which is a golgi body-like structure

- ex. Trychonympha, Trichomonas

Trychonympha

- under Parabasala

- inhabits the gut of termites where it assist in the digestion of wood

FUngi

- the absence of photosynthesis and the lack of motility are its characteristics

- they differ from plants in that they lack chlorophyll and do not perform photosynthesis

- they differ from animals by having cell walls

- genetic sequencing have shown that them and animals are related

Division Zygomycota

- coenocytic molds

- of the approximately 1100 species known, most are saprobes, the rest are obligate parasites of insects and other fungi

- until 2003, taxonomist have thought microsporidia were protozoa, but genetic analysis indicates they are more similar to this division; they are obligatory intracellular parasites (ex. Nosema) which is parasitic on insects such as silkworms and honeybees

- EPA has approved one species of Nosema as a biological control agent for grasshoppers

- seven genera of microsporidia, including Nosema and Microsporidium are known to cause diseases in immunocompromised patients

ciliates, apicomplexans, dinoflagellates

- groups under alveolates

alveolates

- has alveoli (membrane-bound cavities underlying cytoplasmic membrane

- tubular mitochondrial cristae

apicomplexans

- has apical complex of organelles

- e.g. Babesia, Plasmodium, Toxoplasma

ciliates

- has cilia

- e.g. Balantidium, Paramecium, Stentor

Dinoflagellates

- capable of photosynthesis

- has two flagella

- e.g. Gymnodinium, Gonyaulax, Pfiesteria

Foraminifera, Radiolarians, Free-living types

- groups under Amoebae

Amoebae

- has pseudopodia

- lack mitochondria

Naegleria, Acanthamoeba

- free-living types of Amoebae

Entamoeba

- parasitic type of Amoebae

Euglenoids, Kinetoplastids

- groups under Euglenozoa

euglenozoa

- has flagella

- disc shaped mitochondrial cristae

Euglenoids

- capable of photosynthesis

- has pellicle

- e.g. Euglena

Kinetoplastids

- has a single large mitochondrion with DNA localized in kinetoplast

- e.g. Trypanosoma

Diplomonads, Microsporidia

- groups under Diplomonadida

Diplomonadida

- lack mitochondria, golgi bodies, and peroxisomes

Diplomonads

- has two equal sized nuclei

- has multiple flagella

- e.g. Giardia

Microsporidia

- has polar filaments

- e.g. Nosema

Parabasalids

- has single nucleus

- e.g. Trichonympha, Trichomonas

euglenids

- eukaryotic microbes that share certain characteristics of both plants and animals

Zygomycota, Ascomycota, Basidiomycota, Deuteromycetes

- Groups under Fungi

Zygomycota

- has zygospores

- they are coenocytic (aseptate)

- e.f. Rhizopus

Ascomycota

- they have ascospores

- septate

- some associated with cyanobacteria or green algae to form lichens

- e.g. Claviceps, Saccharomyces, Eupenicillium, Tuber, Neurospora

Basidiomycota

- has basidiospores

- septate

- e.g. Agaricus, Cortinellis, Crytococcus, Amanita

Deuteromycetes

- none known spores

- septate

- e.g. Histoplasma, Trichophyton

Chlamydospores

- thick-walled survival spores of fungi

Conidospores

- nonmotile spores borne externally on structures

Nosema

- approved by EPA as biological control agent for grasshoppers

Rhizopus

- also known as Black Bread Mold

Division Ascomycota

- this division contains about 32,000 known species of molds and yeast that are characterized by the formation of haploid spores

- produce asexually by conidospores (e.g. Penicillium)

- most of them spoil food

- includes causative agents of Dutch elm disease and Chestnut blight

ascopores

- haploids spores of ascomycota

asci

- sac surrounding ascospores

ascocarps

- fruiting bodies

- houses asci

- have various shapes

Dutch elm disease and Chestnut blight

- disease caused by agents from Division Ascomycota

- have almost eliminated their host trees in many parts of the US

Claviceps purpurea

- belongs to Division Ascomycota

- grows as hyphae on kernels of rye, wheat, and barley

- produces a substance called ergot (a toxic alkaloid)

- products such as bread made from rye grain may cause ergot rye disease called ergotism (manifested with the following symptoms; numbness, hot and cold sensations, convulsions with epileptic-type seizures, and paralysis of the nerve endings)

ergotism

- this disease is caused by bread made from rye grain

- symptoms: numbness, hot and cold sensations, convulsions with epileptic type seizures, and paralysis of the nerve endings

Saccharomyces

- belongs in Division Ascomycota

- ferments sugar to produce alcohol and CO2 gas

- basis of the baking and brewing industries

Tuber

- belongs in Division Ascomycota

- one of its variety, Truffles, grow as mycorrhizae in association with oak and beech trees to form delectable culinary delights (black truffle = black diamond)

Morchella esculenta (morel)

- its ascocarps (fruiting bodies) is a delectable edible ascomycete

- the pits visible externally are lined with asci (sacs that contain numerous ascospores)

Neurospora

- an ascomycete, known as the pink bread mold

- important tool in genetics and biochemistry

Division Basidiomycota

- its visible fruiting bodies are mushrooms, puffballs, stinkhorns, jelly fungi, bird's nest fungi, or bracket fungi

- important decomposers that digest chemicals such as cellulose and lignin in dead plants and return nutrients to the soil

- are rusts and smuts, which causes millions of dollars in crop loss each year

basidiocarps

- the name of the fruiting bodies of basidiocarps

- e.g. mushrooms

Crucibulum

- basidiocarps (fruiting bodies) of the Bird's nest fungus

Amanita muscaria

- death cap mushroom

- contains potent toxins that affect the liver and nervous system

- produce hallucinatory chemicals or toxins

Crytococcus neoformans

- leading cause of fungal meningitis

division Deuteromycetes (Fungi Imperfecti)

- because scientist have not observed sexual reproduction in all fungi, toxonomist in the middle of the 20th century created this division to contain the fungi whose sexual stages are unknown; either because they do not produce sexual spores or because their sexual spores have not been observed

- analysis of rRNA sequences has revealed that most of them in fact in the Division Ascomycota (thus this is abandoned as a formal taxon)

- they are terresterial saprobes, pathogens of plants, or pathogens of other fungi, several genera are pathogenic to humans

Histoplasma

- under Division Deuteromycetes

- agent of Histoplasmosis (systemic disease; pulmonary, cutaneous, ocular, systemic)

- found in moist soil containing high levels of nitrogen (from droppings of bats, and birds, especially chickens, starlings, and blackbirds) prolonged exposure to these may be hazardous

- the disease does not affect birds or bats

Trychophyton

- under Division Deuteromyces

- agents of ringworm infections

lichens

- forms partnerships between fungi and photosynthetic microbes (either green algae or commonly cyanobacteria)

- the hyphae of the fungus, which is usually an ascomycete, surround the photosynthetic cells and provide them nutrients, water, and protection from desiccation and harsh light

- in return, each alga or cyanobacterium provides the fungus with products of photosynthesis (carbohydrates and oxygen)

- in some, the phototroph releases 60% of its carbohydrates to the fungus

- abundant in pristine unpolluted habitats, grows on soil, rocks, leaves, tree bark, and even backs of tortoises

- they do not consistently grow in the dark depths of the oceans and the back of world of caves (they require light)

soredia

- spores released by lichens as a means of reproduction

- contain both phototrophs and fungal hyphae to new locations where they can establish a new lichen if there is a suitable substrate

fruticose, crustose, foliose

- three basic shapes of lichens

fruticose

- shape of a lichen

- either erect or hanging cylinders (bushy)

crustose

- shape of a lichen

- grow appresed to their substates and may extend into the substrate for several millimeters (crust-like, embedded in substrate)

foliose

- shape of a lichen

- leaf-like with margins that grow free from substrate (loosely attached)

lichens

- they help in the creation of soil from weathered rocks

- may contain nitrogen-fixing cynobacteria, provide nitrogen to nitrogen poor environments

- many animals eat this (reindeer and caribou subsits primarily on this throughout the winter)

- birds use this for nesting materials, and some insects comouflage themselves with this

- humans use this in the production of food, dyes, clothing, perfumes, medicines, and the litmus indicator paper

- uses them to monitor air pollution (they do not grow well in polluted environments)

Chlorophyta (Green algae)

- has chlorophyll a and b, carotene, xanthophylls

- storage products are sugar and starch

- cell wall has cellulose

- lives in fresh, brackish, and salt water; terrestrial

- e.g. Spirogyra, Prototheca, Codium, Trebouzia

Rhodophyta (red algae)

- has chlorophyll a, phycoerythrin, phycocyanin, xanthophylls

- storage product is glycogen (floridean starch)

- cell wall has agar and carrageenan

- lives mostly at salt water

- e.g. Chondrus, Gelidium

Chrysophyta (golden alage, yellow-greem algae, diatoms)

- has chlorophylls a, C1 and C2; carotene, xanthophylls

- storage product is Chrysolaminarin

- cell wall has cellulose, silica, calcium carbonate

- lives in fresh, brackish, and salt water; terrestrial; ice

- e.g. Navicula

Phaeophyta (brown alage)

- has chlorophylls a and c, xanthophylls

- storage products are laminarin and oils

- cell wall has cellulose and alginic acid

- lives in brackish and salt water

- e.g. Macrocystis

Pyrrhophyta (dinoflagellates)

- has chlorophylls a, C1, and C2, carotene

- storage products are starch and oils

- cell wall has cellulose

- lives in fresh, brackish, and salt water

- e.g. Gymnodinium, Gonyaulax, Pfiesteria

Euglenophyta (euglenoids)

- has chlorophylls a and b, carotene

- storage products are paramylon, oils, sugar

- no cell wall

- lives in fresh, brackish, and salt water; terrestrial

- e.g. Euglena

algae

- refer to any simple aquatic plant (in Roman), found in marine habitats

- today, it refers to simple, eukaryotic, photosynthetic organisms that, like plants, carry out oxygenic photosynthesis using chlorophyll a

- differ from plants such as sea grass in having sexual reproductive structures in which every cell becomes a gamete (in plants, portion of the reproductive structure always remains vegetative)

- most of them are aquatic, but can also be found in soil and ice

thalli

- simple multicellular bodies of algae

- commonly composed of branched filaments or sheets

- for large marine algae, commonly called seaweeds, can be relatively complex, with branched holdfast to anchor them to rocks, stem-like stipes, and leaf-like blades

- for larger marine algae, these are buoyed in the water by gas-filled bulbs called pneumocysts

- they are longer than land plants, but lack well-developed transport systems common to vascular plants

pneumocysts

- as-filled bulbs that provide buoyancy to thallis of larger marine algae

asexual reproduction

- reproduction of unicellular algae

- involves mitosis followed by cytokinesis