Envi Sci 114 3
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- Microparasites
-
small size
short generation time
viruses
bacteria
fungi
protozoans
transmission is mostly direct
- Macroparasites
-
large size
long generation time
flatworms, roundworms, flukes
lice, fleas, ticks
fungi
dodder, broomrape, mistletoe
direct or indirect transmission- intermediates
- Parasite transmission
-
microparasites
direct transmission
influenza airborne
smallpox direct contact
cholera water
STDs sexual interactions
- Parasite transmission (macro)
-
macroparasites
direct transmission
endoparasites round worms
ectoparasites lice, mites, ticks, fleas
holoparasites parasitic plants
- ectoparasites
-
on skin feathers, fur
move easily to new hosts
- endoparasites
-
within the host
enter and leave via natural openings
travel internally to point of infection
- Ectoparasite cycle
-
external parasites of birds & mammals
most lay eggs directly on hosts
fleas lay eggs in nests and bedding
larvae leap onto nearby hosts
- Endoparasite cycle
-
roundworms (Ascaris)
eggs expelled with feces
swallowed by susceptible hosts
eggs hatch in intestines
larvae enter blood system and go to lungs
then to mouth –coughed up from lungs
go to stomach, mature, enter intestines
pass out to environment
- HOLOPARASITES
-
plants that lack chlorophyll
nutrients from roots of hosts
seeds germinate
roots grow through soil
attach to roots of host plant
- Intermediate Vectors
-
intermediate organism required
Lyme disease black-legged tick
pathogen: bacterial spirochete
Borrelia burgdorferi
tick moves pathogen from host to host
- Parasites reduce...
-
growth and reproduction
Defense mechanisms require resources - Mutualism
-
relationship between members of two
species that benefits both
more reciprocal exploitation
than cooperative effort
may have evolved from host-parasite
or predator-prey interactions
- SYMBIOTIC MUTUALISM
-
o individuals coexist and their relationship is obligatory
o at least one member depends on the other
o permanent & obligatory mutualism
results in life forms in which the
individual identities and forms of each
organism become indistinct
- Lichens
-
fusion of mutualists
alga + fungi in a body - thallus
alga photosynthesizes - nutrients for both
fungus - shields alga from harmful light
accelerates photosynthsis
absorbs and retains water
and nutrients for both
- Digestive mutualism
-
digestive system of herbivores
bacteria and protozoa
ruminants anaerobic fermentation
in chambers
mammals & some birds & lizards
microflora needed to
digest cellulose in plant tissues
- FIXATION OF GASEOUS NITROGEN
-
N2 is 79% of the troposphere
biologically inert
legumes can fix N2
legume roots attract Rhizobium
bacteria in nodules reduce N2 to NH3
bacteria provide useable N to plant
plant provides C and nutrients to bacteria
- PLANT ROOTS AND MYCORRHIZAL FUNGI
-
most terrestrial plants
in nutrient poor soils
increases uptake of water, nitrogen
and phosphorus
protects against root pathogens
- ENDOMYCORRHIZAE
-
formed by soil fungi that invade
cortical cells of plants
no change in external appearance of root
arbuscules form
uptake of phosphorus from soil increased
increase in water and nutrient uptake
increased plant growth
- ECTOMYCORRHIZAE
-
soil fungi invade roost and grow between
cortical cells
Hartig net formed
external fungal mantle
feeder roots changed in shape to
increase surface area
increased uptake of water & nutrients
defense against root pathogens
- MUTUALISM AS A HOST DEFENSE
-
endophytic fungi in grasses alkaloids
tall fescue, perennial ryegrass
cleaner fish external parasite removal
birds that remove parasites from
skin of large animals
- INDIRECT MUTUALISM
-
mutualistic relationship between
two organisms may be facilitated
by a third species
similar to vector organisms
and intermediate hosts
in parasite/host interactions
- Ozone
-
ozone (O3) normal variable concentration gas in the troposphere
concentration x length of
exposure determines when it is
an air pollutant!
- Affects of Ozone
-
affects visibility
affects human health
affects plant health
- Ozone formation in the troposphere
-
nitrogen dioxide (NO2)
Sunlight required uvB region
Temperature 65F (18.3C)
some level of VOCs
natural
combustion - Sources of VOCs
-
combustion
cars, trucks, buses, planes
heating, power plants
evaporation gasoline, solvents
chemical manufacturing
petroleum refining
natural emissions from vegetation
- OZONE FORMATION BEGINS WITH OXIDES OF NITROGEN (NOx)
-
o Nitric oxide NO
o NO with H2O to nitrogen dioxide
NO2
o NO2 reacts or is deposited
o new NO overnight and early in the
day converted to NO2
o Sources
- Alveoli
-
300 million in lungs
O2 higher in alveoli, diffuses to blood
in surrounding capillaries
CO2 higher in blood, diffuses from blood
into alveoli
- Inhaling Ozone
-
induction of respiratory symptoms
decrements in lung function
inflammation of airways
- Respiratory symptoms of inhaling ozone
-
coughing
throat irritation
pain on deep breathing
chest tightness, shortness of breath
- ozone in the respiratory tract
-
limited solubility in water
not removed in upper respiratory tract
reaches lower tract
dissolves in layer of epithelial
lining fluid (ELF)
throughout the conducting airways
of the lung
- OZONE EFFECTS ON LUNG CELLS
-
ozone: no direct damage to cells
ozonides, aldehydes & hydrogen peroxide
are formed when ozone interacts with unsaturated fatty acids
they are more stable and can damage cells
- LUNG INFLAMMATION
-
damaged epithelial cells release
inflammatory precursors
white blood cells attracted
activate alveolar macrophages
which leads to lung inflammation
antioxidants may also protect
- studies to see effects of ozone on humans
-
animal studies
controlled human exposure studies
field & epidemiological studies
- animal studies of ozone effects
-
Most of what we know comes from lab studies with animals
By using animals we can illustrate a fuller array of effects and exposure conditions than can be investigated in humans
- HEALTH EFFECTS – CONTROLLED EXPOSURES
-
reduced lung function
reduced inspiration and exhalation
discomfort
rapid shallow breathing
cough and pain on breathing
inflammation and cell damage in lungs
decreases as exposure decreases
- PROBLEMS WITH CONTROLLED EXPOSURE STUDIES
-
volunteers usually young healthy men
ozone concentrations are higher than ambient
which guarantees results
results provide no clear threshold for
the general population
- POSSIBLE LONG-TERM OR PERMANENT LUNG INJURY
-
concern that repeated short-term damage
from ozone exposure may permanently
injure lungs
repeated impacts with children may lead to
reduced lung function as adults
accelerated lung function in normal ageing
- LUNG DISEASES
-
ozone may aggravate chronic lung diseases
emphysema
bronchitis
animal studies indicate decrease in immune system function
possible increase in bacterial infections
- AGGRAVATION OF ASTHMA
-
high ozone levels result in more asthma attacks
ozone increases sensitivity to allergens
dust mites
cockroach feces
pets
fungal spores, pollen
- Climate change and ozone
-
climate change
can affect human health
by increasing summer
ozone concentrations
and temperatures