DEPARTMENTAL SEMINAR PRESENTATION …bly.covenantuniversity.edu.ng/sites/default/files/2018-05/PONDERING... · DEPARTMENTAL SEMINAR PRESENTATION DEPARTMENT OF BIOLOGICAL SCIENCES,

DEPARTMENTAL SEMINAR PRESENTATION

DEPARTMENT OF BIOLOGICAL SCIENCES,

COLLEGE OF SCIENCE AND TECHNOLOGY,

COVENANT UNIVERSITY, OTA

TUESDAY 6TH FEBRUARY, 2018

01-May-18Pondering on Light: A friend or foe? - DedekeGA 1

PONDERING ON LIGHT-A

FRIEND OR FOE?DEDEKE, GABRIEL ADEWUNMI

Associate Prof. Eco-Physiology

Federal University of Agriculture, Abeokuta


Outline:

Answering the question “What is light and

its uses”

A look at the nature of light

What concerns an Ecophysiologist with

light?

Light Pollution

Some impacts of visible light on animals

Conclusion


All the fifty years of conscious brooding

have brought me no closer to answer the

question “What are light quanta” Of

course today every rascal thinks he

knows the answer, but he is deluding

himself – Albert Einstein


What is Light?

God said let there be light – Light

phenomenon has miffed man since

ancient times and all life is considered

to have emanated from light; light is

mysterious to us even till now

Light, in the modern age, has

contributed to further civilization and

improve our daily lives


Lights…

There are different kinds of light:

X-rays and Gamma rays, UV, Infrared –

Invisible to the eyes are also different kinds

of lights and visible rays

By wavelength classification, the shorter the

wavelength the higher the energy

(frequency) –

shorter wavelength rays (X-rays & Gamma-

rays) have 10,000 -100,000 times more

energy than visible rays01-May-18Pondering on Light: A friend or foe? - DedekeGA 6

Source:- AgriShift, 2014

Electromagnetic spectrum


Where does light come from…?

There are two kinds of radiation in luminous

phenomenon

1. Natural radiation – creates light by heated

bodies and by low pressure gases – neon, mercury

light

2. Induced radiation – creates a laser beam

In both mentioned above, it occurs when the energy

conditions of electrons inside the substances change.

The energy release then is the light and the

luminous phenomenon occurring in this way is called

natural radiation01-May-18Pondering on Light: A friend or foe? - DedekeGA 8

Neon lights – natural

radiation01-May-18Pondering on Light: A friend or foe? - DedekeGA 9

Induced emission of radiation is a matter of

creating coherent light by amplifying light

generated by the spontaneous emission from

electrons in the metastable state.

The amplification takes place when light is

reflected repeatedly between two mirrors, the

mirrors form a resonant light wave. Because the

light generated by the induced light process has

the same wavelengths and phases, it does not

diffuse even when projected over long distances.

Moreover, when this light is collected, we can get

energy of high density – laser beam.


Use of Light around us

X-ray can be

used to generate

images of the

sun to show

clear

distribution of

the temperature

and lines of

magnetic force

on its surface


X-rays and Gamma-rays are used among other things to investigate

the structure of substances, to control germination of plants and to

cure cancer by using the their high transmission ability and chemical

action


Computer

tomography (CT)

has revolutionized

the world of

medical diagnosis,

it makes a picture

by computer

analysis of the

transmittance of

x-rays01-May-18Pondering on Light: A friend or foe? - DedekeGA 13

Ultraviolet rays are used

for sterilization,

disinfection,

cultivation of plants,

phototherapy,

used in factories which manufacture electronic parts,

used in forensic investigation

aurora image sent by satellite are visible even in daylight when viewed by UV-light,


Infrared rays passed

easily through the air,

hence, are used

to send cloud

photograph captured by

a weather satellite,

for research of natural

resources in geology,

measuring

environmental

pollution,

their heat effect is

useful in medical and

industrial field and also

in many products,

analyzing ancient arts

and writing, 01-May-18Pondering on Light: A friend or foe? - DedekeGA 15

Thermography

converts

infrared rays

radiated

naturally from

the human body

into a picture

indicating the

distribution of

temperature

which is used in

the diagnosis of

diseases01-May-18Pondering on Light: A friend or foe? - DedekeGA 16

Nature of Light…Is light a wave?

Thomas Young, an English Physicist, in 1807,

by his Interference experiment, asserted that

light has the properties of a wave

Further experiment using filters showed that

the region of strong beam consists of high

number of particles massing together while

the region of no light has sparse particles in

them.


Young Interference Experiment


Nature of Light…Is light a particle?

In 1905, Albert Einstein in his light quantum hypothesis now

a theory, succeeded in explaining the photoelectric effect

which had been unexplainable because light was considered

only as a wave.

He asserted that light is a particle containing energy

corresponding to their wavelength.

When blue light is irradiated on metal, it emits electrons from

it. However, when red light is used no electron emission is

observed – hence blue light is particles with high energy

capable of emitting electrons while red light is particles

containing low energy not capable of emitting electrons

Light is therefore, in this way, came to be called photons

(light quanta)- clusters of energy containing energy.


Behaviour of light as particles


Light…is it a wave or particle?

The two observations showed that light has two

characteristics - a wave as well as particles.

It behaves as waves:

when it proceeds or propagated through space – light

propagation.

It behaves as particles:

when energy conversion is a concern such as in the

photoelectric effect, where light interaction with

materials occurred and light is absorbed and emitted.

The various properties of light, are due to the behavior of

extremely small particles called photons that are invisible to

the naked eye..01-May-18Pondering on Light: A friend or foe? - DedekeGA 21

The first ever

photograph of

light as a particle

and wave – Ecole

Polytechnique

Federale de

Lausanne (March

2, 2015)


‘…..we need to become more aware that “light isn’t just light; analysis of the spectral nature of light which we create, and fill our nocturnal world with, is critically important. …… spectral

quality plays a key role in every system………’(Anonymous).

For the rest of my life I will reflect on what light is – Albert Einstein

Should we be concerned with all these?


What concerns an Eco-Physiologist in all these?

Having established that light is more than just the one we

see, my focus will now be majorly directed at a tiny portion

of the electromagnetic spectrum - the visible light

We all are acquainted with the visible light. In some

immediate past, the cry of “up NEPA” and “aww! What’s

wrong with this NEPA?!” rends the air whenever power

outage occurs, especially at night.

The major reason for this uproar all the time, is that apart

from our dependence on electric power for several domestic

and industrial purposes, it is also our source of light in the

night.

The bottomline, light has profound effect on us and our

environment .01-May-18Pondering on Light: A friend or foe? - DedekeGA 24

Visible Light defined

Light in an optical radiation with a spectral power

distribution anywhere within the “visible region”

of the electromagnetic spectrum (approximately

380 nm to 730 nm) radiating from a source (Rea et

al., 2010).

From what has been said it is also evident, that the Whiteness of the Sun’s

light is compounded all the Colours wherewith the several sorts of Rays

whereof that Light consists, when by their several Refrangibilities they are

separated from one another, do tinge paper or any other white Body whereon

they fall. For those colours…are unchangeable, and whenever all those Rays

with those their colours are mix’d again, they reproduce the same white light

as before – Sir Isaac Newton


Seeing light in another light

An article I read on the sea turtles’ hatchlings

and the impact of light pushed me to see light

in another light.

I began to see light in another light from then

on; light has profound effects on us, other

animals and our environment than we ever

thought about of.

Then I also came across the term light

pollution01-May-18Pondering on Light: A friend or foe? - DedekeGA 26

The bright lights from coastal communities

Dave Armstrong 2012 01-May-18Pondering on Light: A friend or foe? - DedekeGA 27

http://www.earthtimes.org/authors/Dave_Armstrong/

What is light pollution?

Light pollution is defined as any alteration of the

natural quantity of light due to the introduction of

artificial light, in particular if this light is dispersed off

the horizontal plain and/or induces negative effects on

living organisms”( Elena and Paolo, 2010).

Light pollution is also defined as the alteration of

natural light levels in the night environment produced

by introduction of artificial light (Fabio et al., 2011).


Types of Light pollution

Three types of light pollution as identified by

Longcore and Rich (2010) are:

Ecological light pollution- “artificial light

that alters the natural patterns of light and

dark in ecosystems.”

Astronomical light pollution - light that

interferes with the view of the night sky.

Aesthetical disruptive light – light that

affects animal physiology01-May-18Pondering on Light: A friend or foe? - DedekeGA 29

Sources of Artificial light pollution

Sports facilities,

Commerce,

Retail,

Agriculture,

Buildings,

Monuments,

Mineral extraction,

Airports,

Sea ports,

Roads,

Streets,

Junctions,

Pedestrian paths and

Parking areas

Significant sources of light pollution as identified by Department for

Communities and Local Government, London (1997) include;


Animals are affected by HPS lighting interference

Dave Armstrong 201201-May-18Pondering on Light: A friend or foe? - DedekeGA 31

http://www.earthtimes.org/authors/Dave_Armstrong/

Effect of Artificial light pollution

Interrupting Dormancy in animals

Alteration in Activity levels

Disruption of bioluminescent behavior

Altering effect on Migration

Alteration of reproductive cycle in animal

Disruption of orientation in animals01-May-18Pondering on Light: A friend or foe? - DedekeGA 32

Behaviour of Loggerhead Sea Turtles on an

Urban Beach II: Hatchling Orientation

Artificial lights, both from nearby or from distant sky glow, can confuse the hatchlings and cause them to crawl onto roads or into communities, often leading to fatal exhaustion, dehydration, predation or even being crushed by cars.

Source: Michael Salmon, Melissa G. Tolbert, Danielle P. Painter, Matthew Goff and Raymond

Reiners (1995). Journal of Herpetology, 29 (4): 568-576 Department of Biological Sciences,

Florida Atlantic University, Boca Raton, Florida.01-May-18Pondering on Light: A friend or foe? - DedekeGA 33

http://www.science.fau.edu/biology/faculty_staff/Salmon.htm

http://www.jstor.org/pss/1564740

http://www.jstor.org/pss/1564740

Turtle hatchlings are disorientated01-May-18Pondering on Light: A friend or foe? - DedekeGA 34

Ecological Impacts of Light Pollution on Wildlife:

Amphibians as Models1. Chronic exposure of Plethodon cinereus to artificial night lighting limit

foraging opportunities, which leads to reduced growth and reproductive

output, survival during winter hibernation, and population size and

distribution.

2. One study examined the effect of artificial night lighting on foraging activity

of common (European) toads, Bufo bufo, at Walton Lake, Milton Keynes, U.K.

3. Artificial light was found to reduce the number of calls and movements by

males of Rana clamitans compared to the control. This may affect selection

of mates (mate choice) by females which may cause changes in the

population dynamics of frogs exposed to artificial night lighting.

4. Night light exposure was found to delay metamorphosis in Xenopus laevis

therefore decreasing their chance of escaping a pool before it dries or cools,

which would increase tadpole mortality.

Source: Wise, S. (2007). Presentation at the International Conference in Defense of the Quality of the Night Sky and the Right to Observe the Stars Starlight -- La Palma, April 19-20, 2007 Department of Biology. Utica College of Syracuse University, Utica, NY U.S.A.


http://www.starlight2007.net/pdf/proceedings/SharonWise.pdf

http://www.starlight2007.net/

Effects on Artificial Night Lighting on Moths

Artificial night light was found to impair the following:

Flight Activity

Vision

Predisposition to predation by Bats

Crypsis (disrupt their camouflage) and easy prey by Birds

Defense Against Other Predators

Courtship and Mating – interferes with hormonal production

Oviposition

Dispersal and Migration

Circadian Rhythms

Trauma

Source: Frank, K.D. (2006) Ecological Consequences of Artificial Night Lighting.

Catherine Rich & Travis Longcore (eds). Island Press. Pages 305-344.01-May-18Pondering on Light: A friend or foe? - DedekeGA 36

http://www.urbanwildlands.org/ecanlbook.html

A common sight of moths being attracted by a floodlight Source:- Catherine and Travis, 2006


Sea squirts like Botrylloides leachi were significantly

reduced in areas polluted by artificial light01-May-18Pondering on Light: A friend or foe? - DedekeGA 38

Source: Catherine and Travis, 2006

Thousands of mayflies

carpeted the ground

around a security light

at Millecoquins Point in

Naubinway on the

Upper Peninsula of

Michigan representing

another huge loss of

reproductive potential

for the species.

Light has three effects on

insects:

Fixated or capture effect

Crash barrier effect,

Vacuum cleaner effect


Effects of light colour and oscillator frequency on earthworm bioactivity

Owa et al.(2008) concluded that

1. The level of performance of the experimental worms (under all the light treatments) was a lot higher; in terms of surface cast production, than that recorded for earthworms in the wild.

2. Of the four light treatments and the control used in this experiment, Hyperiodrilus africanus responded best under the red light treatment, in terms of cast productivity and tolerance.

3. The order of preference for the different light treatments shown by the earthworms, in terms of cast productivity, is red, blue and green in descending order. The white (mixed) light and control (dark) had significantly less stimulating effects on the productivity of the worms.

4. H. africanus is less likely to emigrate from an area, farm or vegetation, where they are exposed to red light or an oscillator of the frequency band about 44 KHz.

Owa, S. O., Peters, S., Dedeke, G. A. and Aladesida, A.A. (2008). African Journal of Agricultural Research Vol. 3

(1), pp. 029-036, Available online at http://www.academicjournals.org/AJAR ISSN 1991-637X01-May-18Pondering on Light: A friend or foe? - DedekeGA 40

Haemolymph Electrolytes, Acetylcholinesterase and Melatonin Activities of Giant

African Land Snail (GALS) (Archachatina marginata) exposed to Monochromatic

Lights.

Exposure to varying wavelengths of light

elicited varied responses in the haemolymph

electrolyte concentrations of GALS.

Exposure to red light and total darkness

enhanced the activities of acetylcholinesterase

and melatonin in the haemolymph but were

suppressed by blue and yellow light.

Dedeke, G.A., Okulaja, Y., Ogunnaike, M., Awesu, A. and Kehinde, F.O. (2017). Haemolymph Electrolytes,

Acetylcholinesterase and Melatonin Activities of Giant African Land Snail (GALS) (Archachatina marginata) exposed to

Monochromatic Lights. Journal of Molluscan Research 3:81-90. Published by Research Network on Giant African Land

Snails (NetGALS).


Impact of exposure to light spectral on fruitfly, Drosophila melanogaster

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

AMBIENT BLUE RED WHITE YELLOW

PER

CEN

TA

GE (

%)

LIGHT TREATMENTS-10

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10 11 12 13 14

CU

MM

ULAT

IVE F

REQ

UEN

CY

DAYS

TREND OF MORTALITYAMBIENT

BLUE

RED

WHITE

YELLOW

Source: Dedeke, G.A., Emuze, A.J. and Kehinde, F. Impact of exposure to light spectral

on Drosophila melanogaster (Unpubl Data -2018)

The trend of mortality of Drosophila on

exposure to different light spectra

The percentage mortality of Drosophila on

exposure to different light spectra


Potential of light spectral in the control of mosquito

Dedeke, G.A., Rasak, I.B. and Kehinde, F. The use of light spectral in the control of

mosquito (Unpubl Data - 2018)

AMBIENT BLUE GREEN RED WHITE YELLOW

-20.0

0.0

20.0

40.0

60.0

80.0

100.0

LIGHT TREATMENTS

PE

RC

EN

TA

GE

ADULT

MORTALITY

UNDEVELOPED

Percentage of mosquito larvae that developed into adult, larvae mortality, and undeveloped pupae on

exposure to light of varying wavelength for fourteen days


Potential of light spectral to control damage of stored beans

by the bean beetle, Callosobruchus maculatus

Light

Treatment

N

(Replicate)

No of beans

per

Replicate

Mean Number

of Perforated

Beans

Percentage

Damaged

Beans

CONTROL 3 702 124.67±16.56d 17.76

BLUE 3 702 16.67±1.53a 2.38

GREEN 3 702 61.00±17.44b 8.69

RED 3 702 17.33±4.51a 2.47

WHITE 3 702 13.67±3.79a 1.95

YELLOW 3 702 96.33±6.66c 13.72

0

2

4

6

8

10

1 2 3 4 5 6 7 8 9 10

NU

MB

ER

DAYS

WHITE

GREEEN

RED

BLUE

YELLOW

CONTROL

Source: Dedeke, G.A., Popoola, I. and Kehinde, F. Potential of light spectral to control damage of

stored beans by the bean beetle, Callosobruchus maculatus (Unpubl Data – 2018)

Trend in daily mortality of beans weevils housed with beans on

exposure to light of varying light spectral for ten days

Percentage Damaged beans by the bean beetle during exposure to

light of varying spectral for ten days


Likely Neurophysiologic Pathways…

There following are likely proposed pathways

through which light elicits the different effects in

animals

Light impinges on the retina – Retinal ganglion

cell - the Optic nerve – pituitary gland – temporal

lobe – occipital lobe of the brain –

informing the conscious centre of our brain of our

surrounding without interprepration

Direct connection of additional nerve bundles

from the retino-hypothalamic tract (RHT) –

affect the ANS01-May-18Pondering on Light: A friend or foe? - DedekeGA 45

Likely neurologic pathways cont’d…

A side branch of the RHT to the amygdala directly

bypassing the hypothalamus – colour sensitivity –

each frequency in the colour spectrum produce its own

specific neurological and psychological effect

A fourth nerve connection from the retina via the

lower optic tract (not used for vision) reaches the

transpeduncular nucleus (midbrain) (light and

colour sensitive) –

signal travels via the superior cervical ganglion back via the

brain stem to the pineal gland – this is responsible for the

circadian day-night rhythm and melatonin production in the

pineal gland when it gets dark01-May-18Pondering on Light: A friend or foe? - DedekeGA 46

Pathway cont’d…

Through the subconscious mind, immune system,

the limbic system, the nervous system.

Light – charge particles (travelling in the lymph and

blood as well as in nerve axons) like albumin which

was found to be able to be charged by coloured

light and able to deliver this charge to tissues far

away from the site of exposure.

Through the outer skin layer,

light also affects pigments, fluorescent particles in

the body fluids and inside the cells, that travel in

the blood and lymph01-May-18Pondering on Light: A friend or foe? - DedekeGA 47

Likely Neurophysiologic Pathways… ipRGC – Retinal-

ganglion cell

SCN – Suprachiasmatic Nucleus

PVN – Paraventricular Nucleus

DMN - Dorsal Medial Nucleus

LH -Lateral hypothalamus

SPZ -Subparaventricularnucleus/zone

VLPO - Ventrolateral preoptic nucleus

OPN - Olivary pretectal nucleus

EWN - Edinger-Westphal nucleus

ipRGC

SCN

PVNDMN

of the

hypothalamus

intergeniculate

leaflet

LH

OPN

VLPO

SPVZSplanchnic

and vagus

Nerves Amygdala and

lateral

habenula EWNPineal

gland


Conclusion Light has profound effect on the body’s metabolism; it has profound

effect on the hormone system, the emotions, stress levels, sleep, brain

function…Its different wavelengths elicit remarkable changes in the

concentrations of neurotransmitters such as melatonin, norepinephrine,

serotonin, beta-endorphin, cholinesterase…in the cerebro-spinal fluid of

animals. All these will in turn result in the physical, chemical and

behavioural changes which take place in animals.

Has light affected us, the animals, and our

environment in a tremendous way? Yes it has.

Is our life intertwined with light in an

inextricable manner? Yes our life is.

Is light then a foe or friend? I leave the answer

to that question to you. 01-May-18Pondering on Light: A friend or foe? - DedekeGA 49


Documents

DEPARTMENTAL SEMINAR PRESENTATION …bly.covenantuniversity.edu.ng/sites/default/files/2018-05/PONDERING... · DEPARTMENTAL SEMINAR PRESENTATION DEPARTMENT OF BIOLOGICAL SCIENCES,