slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Biomarkers in ecotoxicology PowerPoint Presentation
Download Presentation
Biomarkers in ecotoxicology

Loading in 2 Seconds...

play fullscreen
1 / 39

Biomarkers in ecotoxicology - PowerPoint PPT Presentation


  • 390 Views
  • Uploaded on

Biomarkers in ecotoxicology. Biomarkers. Classic definition: Biochemical, physiological or histological indicators of either exposure to or effects of, xenobiotic chamicals at the suborganismal or organismal level.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Biomarkers in ecotoxicology' - felton


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Biomarkers in

ecotoxicology

slide2

Biomarkers

Classic definition:Biochemical, physiological or histological indicators of either exposure to or effects of, xenobiotic chamicals at the suborganismal or organismal level

Nato workshop (1993):A biological response that can be related to an exposure to, or toxic effect of, an environmental chemical or chemicals

Depledge (1993):A biolochemical, cellular, physiological or behavioural variation that can be measured in tissue or body fluid samples at the level of the whole organism (either individuals or populations) that provides evidence of exposure (exposure biomarkers) to and/or effects (health biomarkers) of one or morechemical pollutants

slide3

Health and stress

Health (Bayne et al., 1985):The residual capacity of an organism to withstand stress.

Stress (Brett1958):A state produced by an environment or other factor which extends the adaptive response of an animal beyond the normal range, or which disturbs the normal functioning to such an extent that the chances of survival are significantly reduced

Stressor (Lugo,1981):A stressor is any condition or situation that causes a system to mobilise its resources and increase its energy expenditure. Stress is the response of the system to the stressor via this increase in energy expenditure.

slide4

The driving forces behind biomarker development

  • The problems with chemical analysis
    • What do we measure?
    • Temporal fluctuations in exposure
    • Sensitivity vs effect?
    • Bioavalability?
  • Proof of exposure
  • Proof of effect
  • Prediction of ecological effects
slide5

Chemicalpollution

- speciation

- bioavailable residues

Sensory

interference

Absorption

Exposure / effect

biomarkers

Molecular responses

Physiological responses

Structural damage

Predictive

Effect / health

biomarkers

Impaired fitness

Disturbed population and

ecosystem stability

Reactive

slide6

Biomarkers

An ideal Healthbiomarkeris sensitive to chemical stress and is irrefutably linked to the Darwinian fitness of the organism.

Darwinian fitnessis the combined relative probability of survival and rate of reproduction of the individual.

An ideal Exposure biomarkeris both sensitive and specific to exposure by a single chemical or group of chemicals.

The ideal biomarkerin ecotoxicology combines the properties of both types.

Depledge, 1993

slide7

Healthy

Stressed

Health Status

curable

Non-curable

Reversible

Irreversible

Homeostasis

Compensation

Non-compensation

Intensity of Biomarker

response

Intensity of Exposure

Depledge’s biomarker christmass wish 1993

slide10

Lead poisoning

  • A historically prominent environmental toxin
  • Symptomer: Porphyria/anaemia
  • Abdominal pain
  • Constipation
  • Peripheral neuropathy, Madness
  • Weight loss
  • Requirement: early warning biomarker
  • ALAD: 5-aminolaevulnic acid dehydratase
slide11

Chlorophyl

Vitamin B12

etc

Pb

Pb

Pb

slide12

The ALAD monomer

Zn binding site

slide15

The effect of lead contaminated diet on duck body weight

24% clean sediment in commercial diet

24% Pb sediment in commercial diet

Heinz et al, 1999

slide17

Biomarker development

  • After Hugget et al. (1989)
  • Relative sensitivity
  • Inherent variability
  • Biological specificity
  • Chemical specificity
  • Time to manifestation
  • Linkage to higher level effects
  • Field applicability
  • Field validation
slide19

Paraoxonases

A-esterases

(hydrolyse OP’s)

DFPase

Acetylcholinesterase

B-esterases

(Inhibited by OP’s)

Buturylcholinesterase

Neurotoxicesterase

Carboxylesterase

Esterase classification

C-esterases: Do not interact with OP’s or Carbamates

slide20

RO

OR

-

CH3

CH3

O

O-P-S-R

H3C-N-CH2-CH2-O-C-CH3

OH

+

OH

-

-

Acetylcholine-receptor complex

Organophosphate-receptor complex

Hydrolysis

Hydrolysis

OR

-

O

CH3

CH3

CH3

O=P-S-R

H3C-N-CH2-CH2-OH

C

OH

+

O

+

-

Acetylcholine hydrolysed but bound

-

CH3COOH

+

(CH3)NCH2CH2OH

OR

Product release (rapid)

O=P-S-R

Product release V slow

O

-

OH

-

OH

-

Regenerated enzyme + choline +acetic acid

AChE Inhibition

slide21

Biomarker development

  • After Hugget et al. (1989)
  • Relative sensitivity
  • Inherent variability
  • Biological specificity
  • Chemical specificity
  • Time to manifestation
  • Linkage to higher level effects
  • Field applicability
  • Field validation
slide22

2PAM

N

CH

CH3

N

O

H

Relative specificity

  • Species differences
  • Intraspecific differences
    • Use of oximes to reactivate enzyme
    • Brain AChE shows least variablilty
slide24

2PAM

N

CH

CH3

N

O

H

Relative specificity

  • Species differences
  • Intraspecific differences
    • Use of oximes to reactivate enzyme
    • Brain AChE shows least variablilty
  • Diurnal changes (up to 150% in starling)
  • Seasonal changes (Brain AChE lowest var.)
  • Age
slide25

Effect of age I

100

80

60

Percentage of adult activity

40

20

0

4

365

18

Age of starlings (days)

Grue et al., 1981

slide26

Effect of age II

1200

1000

300

800

Plasma BChE (µmol/min/l plasma)

Plasma BChE (µmol/min/l plasma)

600

200

400

200

100

1

2

4

7

12

Age of mallard (weeks)

Bennett and Benet., 1991

slide27

Relative specificity

  • Species differences
  • Intraspecific differences
    • Use of oximes to reactivate enzyme
    • Brain AChE shows least variablilty
  • Diurnal changes (up to 150% in starling)
  • Seasonal changes (Brain AChE lowest var.)
  • Age
  • Temperature/diet
slide28

Controls

Cold

Underfed

Parathion

(15 mg/kg)

Effects of temperature and diet

on ChE activity in Quail

3

Plasma ChE (IE/l plasma)

2

1

1

3

7

14

28

Days

Ratner, 1982

slide29

Biomarker development

  • After Hugget et al. (1989)
  • Relative sensitivity
  • Inherent variability
  • Biological specificity
  • Chemical specificity
  • Time to manifestation
  • Linkage to higher level effects
  • Field applicability
  • Field validation
slide31

Biomarker development

  • After Hugget et al. (1989)
  • Relative sensitivity
  • Inherent variability
  • Biological specificity
  • Chemical specificity
  • Time to manifestation
  • Linkage to higher level effects
  • Field applicability
  • Field validation
slide32

Starling serum

ChE activity,

6hrs and • 24hrs after OP ingestion

Thompson et al 1991

.

slide34

Biomarker development

  • After Hugget et al. (1989)
  • Relative sensitivity
  • Inherent variability
  • Biological specificity
  • Chemical specificity
  • Time to manifestation
  • Linkage to higher level effects
  • Field applicability
  • Field validation
slide35

Links to fitness-related behaviours

Activity budgets of captive male starlings dosed with dicrotophos to give a 50% inhibition of AChE.

%

Grue and Shipley, 1981

slide36

Biomarker development

  • After Hugget et al. (1989)
  • Relative sensitivity
  • Inherent variability
  • Biological specificity
  • Chemical specificity
  • Time to manifestation
  • Linkage to higher level effects
  • Field applicability
  • Field validation
slide37

Zone of normal variation

Zone of reversible effects

Zone of irreversible effects

g/ha

280

420

?

Dose of Fenitrothion

The utility of AChE mesurements in environmental management

0

20

40

% inhibition of AChE

60

80

mg/Kg

1

3

10

slide39

Depledge’s Christmass wish is unlikely to be fulfilled in near future

Conclusions

  • It is important to understand toxic mechanistic when attempting to understand environmental dammage
  • Attaching blame to an environmental sinner will also in the future involve the use of biomarkers