Endocrine Disruptors, Crustacean Molting and Bivalve Populations. Peter L. defur Virginia Commonwealth University Richmond VA

Transcription

1 Endocrine Disruptors, Crustacean Molting and Bivalve Populations Peter L. defur Virginia Commonwealth University Richmond VA

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3 Not so long ago, and not so far away We are certain of the following: a large number of man-made chemicals that have been released into the environment have the potential to disrupt the endocrine system of animals, including humans.

4 Research on Estrogenic Compounds Ana Soto, Tufts University Breast cancer cells MCF7 cell line Control cells began to grow Search for the cause led to the plastic Plastics leaching into the culture medium Nonyl phenol Tests for other EDC s in animals and cell lines

5 Model of how EDC acts on hormone-receptor interactions EDC hormone hormone R EDC EDC R R Mimic normal action Abnormal action Blocked action R= hormone receptor; EDC = endocrine disrupting chemical

6 A Brief History of EDCs 1991 Ana Soto nonyl phenol 1992 Colborn and Clement 1993 Colborn et al. EHP 1996 Colborn, Dumanoski and Myers 1996 SDWA and FQPA in Congress 1998 EDSTAC 1999 defur et al - invertebrates 2008 Congressional ban on phthalates

7 Gull nest with two sets of eggsdouble clutch

8 Hooked beak cormorant

9 Chick: Premature Foliage

10 NRC 1999 Hormonally Active Agents in the Environment Adverse reproductive and developmental effects have been observed in human populations, wildlife, and laboratory animals as a consequence of exposures to HAA s... prenatal exposure to these HAA s can affect the developing nervous system.

11 Endocrine Disruptors Interact with hormone systems Alter normal functions Impair development Either synthetic or natural Act at any level of the hormone- action cascade Any animal with hormones

12 Figure 3-1. Evaluating effects of potential EDCs on invertebrates: A life-cycle context. F1 F0 Embryo Adult Gamete production Fertilization Larval Gonadal maturation Juvenile

13 Steroid Hormone Mechanism of action Hormone diffuses into cell Binds to receptor Carrier molecules? Activated complex Migrate into nucleus DNA binding Initiate mrna Protein synthesis Biological response Taken from Norris, Vertebrate Endocrinology

14 DDT Bag

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17 Hormone systems affected by EDC s Estrogen Androgen - testosterone Thyroid Ecdysone Juvenile Hormone Molting inhibiting hormone

18 Some points where EDC s may affect hormone systems Hormone synthesis Hormone release and transport Hormone recognition and uptake Binding to receptor Activation and biochemical process DNA transcription/translation Metabolism and breakdown

19 Known or suspected EDC s include various compounds Insecticides- methoprene Fungicides vinclozolin Herbicides- atrazine Phthalates Phenols Dioxins, PCB s, etc. Some metals

20 17B-Estradiol Diethylstilbestrol (DES) DDT Coumestrol

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22 Endocrine Disruption in Invertebrates (1999).. endocrine disruption in invertebrates stems from exposures to pesticides specifically designed to disrupt endocrine-regulated processes such as growth, metamorphosis and molting. These chemicals act as ecdysone antagonists or JH analogs.

23 Invertebrate ED s invertebrates are susceptible to the same modes of endocrine disruption (i.e. hormone agonists and antagonists, modulation of endogenous hormone levels) as observed with vertebrates. tribybutyltin seems to function by altering normal androgenic mechanisms in gastropod snails..

24 Environmental/Physiological Stimuli (i.e., associated with sexual maturation) Neuroendocrine Glands (i.e., hypothalamus, pituitary) Target Tissues (i.e., prostate, liver) Endocrine Glands (i.e., gonads, thyroid)

25 Invertebrate Hormones Steroids Terpenes Proteins Neuropeptides-5 HT, serotonin, FARPS- fmrfamide family Phe-met-arg-phe-amide

26 NH2- Ile - Ser - Ile - Asn -Gin - Asp-Leu - Lys - Ala - Ile - I Thr-Asp-Met -Leu -Leu-Thr -GIu -Gin -Ile -Arg Glu - Arg - Gin - Arg - Tyr -Leu - Ala - Asp- Leu-Arg Gin-Arg - Leu- Leu - Glu-Lys-OH Egg Laying Hormone of Aplysia

27 TBT is the best known- and possibly studied

28 Characteristic spawning behavior Fertility, fecundity, gamete release, other reproductive functions; shell formation

29 Much of arthropod endocrinology based on insects originally, but now includes macro-crustaceans and micro-crustaceans such as Daphnia. Toxicology was on Mysids, now Daphnia Molting process worked out for true crabs, shrimp and applied to others

30 OH OH OH OH OH HO HO H O OH HO HO H O OH Ecdysone 20-Hydroxyecdysone OH OH OH OH OH HO HO H O OH HO HO H O OH Makinsterone A Ponasterone A OH OH OH HO O H O OH HO HO H O OH 3-dehydroecdysone 25-deoxyecdysone

31 Insect Juvenile Hormone

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34 Molt Stages C = intermolt D0 = early pre-molt D1 = most pre-molt events occur D2-4 = late pre-molt, few events E = ecdysis The Molt A = soft shell B = paper shell

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39 Endocrine control of molting in decapods Sinus gland MIH Molting gland Mandibular organ MF + + Ecy? Target Tissues: muscle, epidermis

40 Procedures Procambarus clarkii from Louisiana Juveniles reared in the lab gm animals similar in size to grass shrimp Molt stages determined as per grass shrimp LD 50 on juveniles x3

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42 % Mortality Mortality by Molt Stage B C Do D1' D1" D1"' Molt Stage Total percent mortality across all treatments based on molt stage.

43 Percent Mortality by Molt Stage % Mortality B C Do D1' D1" D1"' Molt Stage Control 0.65 ppb ppb ppb Percent mortality in each treatment with respect to molt stage.

44 Average MO Average Oxygen Uptake by Molt Stage C Do D1' D1" Molt Stage Average FW MO2 Ave. Endosulfan MO2 Average oxygen uptake for juvenile crayfish across intermolt (stage C) and premolt (stages Do - D1 ).

45 Ecdysone levels (pg/ul) in P. clarkii following endosulfan exposure as a function of molt stage Animals Mean S.E. Range Adults Juv C Juv D

46 Conclusions Endosulfan is highly toxic to P. clarkii, more so to juveniles Dose response function is not linear it is an inverted U curve Pre-molt animals are most sensitive stage Oxygen uptake is affected, BUT Effect on Ecy is undetermined

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