chapter 21- environmental regulation in animal development red abalone- must bind coralline red...
TRANSCRIPT
Chapter 21- Environmental regulation in animal development
•Red abalone- must bind coralline red algae to begin ___________________
•Mosquito- _________________ triggers egg production
•______________________________ •Algae provides photosynthetic energy to amphibian eggs when in tight clusters
1. Many examples of environmental regulation exist
•A bacterium multiplies only in leaf hopper __________
•No bacterium= embryonic death due to lack of _________________ development
1. environmental regulation (cont.)
•Aphids hatch only _________ in the spring, but male and female are hatched in the autumn (mechanism unknown)
•Many insects use __________- a suspension of development due to harsh conditions (e.g winter condition)
•Nitrogen fixing ________ provide nitrogen to legumous plants (e.g. bean plants)
•Diapause is not triggered by harsh conditions, but before the harsh conditions arrive
•Gravity/pressure
•A chick embryo requires proper positioning to _________________________
•Also effects development of bones in chicken
2. ____________________- express distinct phenotypes depending on circumstances
a. _______________ dictates grass hopper development
Low density phenotype
High density phenotype
Fig. 3.3
Fig. 21.6
_________ phenotype
_________ phenotype
b. ______ dictates wing color in certain butterflies
Termed “______________”
2. Phenotypic plasticity- (cont.)
c. ______________-dependant sex determination
Recall Temperature-dependent sex determination in reptiles (Ch. 17)
• Crocodiles- temperature extremes result in female
Advantage- increase sexual reproduction if ____ male:female ratio
Disadvantage- less adaptable to slight environment change (e.g. ______________)
• Blue headed Wrassse (reef fish) -
•If wrasse reaches reef with males, it develops into _____
•If wrasse reaches reef without males, it develops into ___
•If male dies, largest female becomes male within _______
d. __________-induced polypheism
a. Organisms change shape in response to soluble factors released by predators
typical
Predator induced
Fig. 21.13
CarpMolluskBarnicle ???Daphnia ???
_____ _____ ____ ____ ______Survival Rate(typical/induced)
No predation until 50% of typical morphs eaten
•The immune system “_____________” its foreign invaders
3. Predator-induced polypheism (cont.)
b. Mammalian immunity
•A foreign object (antigen) is recognized by a one in __ _________ B-cells
•Only the B-cell that recognizes the antigen will __________ and secrete specific antibody to _________ the antigen
4. Learning is an environmentally induced system
a. New neurons are produced • in _______ learning a song • in ________ learning activities
b. Visual pathway development is affected by _______
• A flash of light seen by a cortical neuron right eye is also “seen” by the corresponding cortical neuron in the left eye
•If sew right eye of newborn closed for ________, they were functionally ______ in right eye
•Kitten experiments
•If sew both eyes of newborn closed for 3 months, vision remains (though weak) in ________
4. Learning is an environmentally induced system
•Kitten experiments (cont.)
•Critical window of development is 4 weeks to 3 months
Thus, not all development is encoded in the ______• Some is the result of ___________
•If sew either eye shut after first three months- __ __________
•Thus, synapses have been stabilized by 3 months
2. __________ plays key role in determining whether neuronal connections ____________
Two key principles-
1. ______________ are made prior to when the animal sees
Also- the _________________ phenomenon is due to learning
5. Environmental disruptions to development
•About _____________ of human conceptions survive to term
•About ____ of human babies have a recognizable deformation (normally in limbs, lungs or face)
•Abnormalities caused by exogenous agents are called ________Examples-
•Skunk cabbage induced _______ in sheep
In Humans
_______________________
•Quinine ________
•Smoking (>20/day)
•Alcohol (>2oz/day) ____________________
•Abnormalities caused by genetic mutations agents are called ____________ (e.g. Down’s syndrome, aniridia (Pax6 mutation))
a. Retinoic acid as a teratogen
Accutane-for treating severe ____
________ women of childbearing age have used Accutane
1985 study of pregnant Accutane users
•____ “ normal”•_____aborted spontaneously•_____ with anomalies- absent ears, small jaws, cleft palate, and/or CNS problems
Estimated that__ of pregnancies in America are unplanned
5. Disruptions (cont.)
•FAS children have mean IQ of __; at 16.5 yrs, they have vocabulary of ___ yrs
•Estimated that _______ of children born to alcoholic mothers will have FAS
b. Alcohol is a teratogen
•Fetal alcohol syndrome (FAS) is __ most prevalent type of mental retardation (behind fragile X and Down Syndrome); ______ children in USA
CH3CH2OH
Fetal Alcohol Syndrome
Huge problem in South Africa due to alcohol-based economy
Misshapen eyes, flat nose, long upper lip
c. Pathogens as teratogens-
•______ can cause deafness, heart malformations
•_____________ and cytomegalovirus can cause deafness, blindness, mental retardation
•Syphilis can cause deafness or death
d. Chemicals as teratogens-•________________, and zinc are common ones
•In Kazakhstan (former Soviet Union) nearly __ of population have extensive chromosome breakage due to “industrial production at all costs”
e. Estrogen
•DDT is a banned insecticide that can act like ________
•DDT is linked to increased incidence of __________ and decreased _____ ________
•Dioxin (dumped at Times Beach west of St. Louis) is linked to increased _____ _____ and decreased ____________
1985-Industrial plant in Italy explodes-
•Breast cancer ____________in immediate perimeter•Breast cancer ___________ in surrounding area
e. Estrogen (cont.)
•_____________ (used to harden plastics used in plumbing and milk/orange juice containers)- replaces role of estrogen to induce certain cultured cell to divide
•PCBs (previously used as refrigerants); banned in 1970 due to cancer-causing ability in rats; yet remain in environment
•Blamed for reduced reproductive capacities in seals, mink and fish
Dramatic increase in deformed frogs in US- Due to toxins in water?