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Chapter 21- Environmental regulation in animal development Red abalone- must bind coralline red algae to begin ___________________ Mosquito- _________________.

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Presentation on theme: "Chapter 21- Environmental regulation in animal development Red abalone- must bind coralline red algae to begin ___________________ Mosquito- _________________."— Presentation transcript:

1 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

2 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

3 2. ____________________- express distinct phenotypes depending on circumstances a. _______________ dictates grass hopper development Low density phenotype High density phenotype Fig. 3.3 Fig _________ phenotype b. ______ dictates wing color in certain butterflies Termed “______________”

4 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 _______

5 d. __________-induced polypheism a. Organisms change shape in response to soluble factors released by predators typical Predator induced Fig CarpMolluskBarnicle???Daphnia??? _____ ____ ______ Survival Rate (typical/induced) No predation until 50% of typical morphs eaten

6 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

7 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 ________

8 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

9 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))

10 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.)

11 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

12 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”

13 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

14 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?

15 Other teratogens ____________(fallout) Infectious agents- Herpes simplex II, cytomegalovirus, rubella Drugs- alcohol, aminopterin, chlorophenyls, tetracyclines, thalidomide Other possible teratogens- _______ ___________, lithium, zinc deficiency


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