Cultured - Lynn Margulis.

An interview with the great Lynn Margulis, who proposed the endosymbiotic theory.
Video produced for the Creativity and Problem Solving assignment, Dr. Mike Wride - Trinity College Dublin.

Movie created by students: Marília Dutra Jacques, Niamh Mullins and Aoife Hosford.

Marie Curie and Radioactivity: A Silent Movie

This silent movie on Marie Curie and radioactivity was made by Junior Sophister Functional Biology students Emily Conan, Katie Geoghegan, Timothy Reed and Laura Sheridan, for the assignment for the tutorial sessions on Problem Solving and Creativity in Science with Prof Mike Wride, School of Natural Sciences TCD.
.... And there is a cameo role for Prof John Parnell too!

Insects wearing shades: considering the effect of polarised light on insects!

By Catriona Daly

Junior Sophister Functional Biology Student

 

Polarised light is hugely important in nature. It can affect the growth of plants or the daily rhythm of insects (Csabai et al., 2006; Shibayev and Pergolizzi, 2011). Some animals, such as cuttlefish or insects, use polarised light for navigation (Cartron et al., 2012). Humans also have some perception of polarised light. In 1884, Haidinger noticed that if one looks at light at a particular angle, blue-yellow brushed shapes appear on the centre of the fovea (Le Floch et al., 2010). However, in day to day life, we do not notice polarised light. Interestingly, some scientists believe that we need to consider how manmade structures will affect animals with polarised vision. Wildermuth and Horvat (2005) noted that buildings or objects can reflect polarised light in a way that confuses animals, particularly insects. There are several human inventions which are disorienting to animals, namely cars, asphalt and glass buildings. We have a responsibility to make sure that the human world is as animal friendly as possible.

Polarisation is the direction of vibraton of the electric field vector of light. Light can be unpolarised, linearly polarised at a particular angle or circularly polarised either clockwise or anti-clockwise (Kleinogel and White, 2008). Many animals rely on polarised light for navigation (Cartron et al., 2012). Turcsányia et al. (2009) showed that mayflies detect water bodies by the horizontal reflection of polarised light. Unfortunately, other man-made surfaces can give off similar horizontally polarised light. Wildermuth and Horvat (2005) discovered that dragonflies or Libuella depressa can mistake a car bonnet for a body of water. Male Libuella depressa become territorial and fiercely defend the car as they would a normal habitat. This misconception was not limited to males. Stevani et al. (2000) found that female dragonflies were ovipositing on cars and damaging the clearcoat. Kriska et al. (2006) noted that red and black cars are most at risk as the degree of linear polarisation from red or black car bonnets is high. Car owners who live near tracts of water are recommended to buy 'green' cars in colours that will not lead to misplaced mayflies. Light coloured cars are best, though a very dirty car will also have a lower degree of polarisation, allowing for water as well as mayflies to be saved.

A second example of an insect 'trap' is an asphalt road (Kriska et al., 1998). The dark, smooth surface mimics the homogeneity of a body of still water. An experiment was conducted with mayflies or ephemeroptera. It found that long roads with an open sky above are a prime site for mayfly swarming and breeding en masse. The higher temperature of the asphalt even allows reproductive activity to go on longer. Eggs are then deposited on the road, 6- 9 thousand per fly, and all are destroyed. Mayflies have a very short sexual maturity and may not be able to breed again (Brodskiy, 1973). To confirm that the reflected polarised light was the reason for this strange choice of oviposition, tests were carried out on the attractiveness of coloured cloths. It was found that shiny dark material, which also reflected light in a similar way to water, was the most attractive (Kriska et al., 1998). They recommended light coloured markings on the road to help insects identify it correctly.

Finally, insects are also prone to mistaking glass buildings for bodies of water. Kriska et al., (1998) noted that polarotactic Hydropsyche pellucidula or caddis flies were being lured to glass buildings. They were baffled to find that the insects would alight on the vertical glass panes and proceed to copulate. A large amount of time was spent overall on the surface of the buildings with flies leaving for a few seconds at a time and returning quickly. This was repeated for several hours. The caddis flies did not lay their eggs on the buildings but returned to horizontal water bodies to oviposit (Reich and Downes, 2003). This behaviour surprised researchers as it indicated that the flies understood that the surface they were on was not horizontal, yet they remained on the surface. They concluded that the flies would land on the glass and, with less reflection visible from up close, recognise that it was not horizontal. Once they left, the attraction mechanism would kick in again. Kriska et al., (1998) found that at certain angles, an insect flying toward a vertical glass surface can interpret it as a flat body of water. The angle at which optimum polarity was observed was a specific angle known as Brewster's angle (Roldan-Carmona, 2012). When light hits a transparent surface at this angle, the reflected light is perfectly polarised. This explains why caddis flies are particularly attracted to glass surfaces. It was found that anything that breaks up the homogeneity of the surface, such as blinds or open windows, decreases the amount of polarised light. Owners of large glass buildings could deter caddis flies with some light coloured blinds or curtains.

It is clear that polarised light plays a huge role in insect vision. Thousands of insect eggs are destroyed due to incorrect navigation by polarised light. Insects recognise large dark areas as water because, in nature, that is exactly what is there. Humans have changed the face of this earth and they have a responsibility to make sure at it is still amenable to animals and their habits. By following the few simple recommedations in these experiments, people living near water can make a huge difference to the lives of insects.

References

Brodskiy, A. K. (1973). The swarming behaviour of mayflies. (Ephemeroptera). Entomology Review, 52 ,33-39.

Cartron L., Darmaillacq A.S. , Jozet-Alves C., Shashar N. and Dickel L. (2012) Cuttlefish rely on both polarized light and landmarks for orientation. Animal Cognition, 15, 591-596.

Csabai Z., Boda P., Bernath B., Kriska G. and Horvath G. (2006) A 'polarisation sun-dial' dictates the optimal time of day for dispersal by flying aquatic insects. Freshwater Biology, 51, 1341-1350.

Kleinlogel S. and White A. G.(2008) The Secret World of Shrimps: Polarisation Vision at Its Best. Public Library of Science One, 3, e2190.

Kriska G., Horvath G. and Andrikovics A. (1998) Why do mayflies lay their eggs en masse on dry asphalt roads? Water-imitating polarized light reflected from asphalt attracts Ephemeroptera. The Journal of Experimental Biology, 201, 2273-2286.

Kriska G. ,Csabai Z. ,Boda P., Malik P. and Horvath G. (2006) Why do red and darkcoloured cars lure aquatic insects? The attraction of water insects to car paintwork explained by reflection-polarization signals. Proceedings of the Royal Society Biological Sciences, 273, 1667-1671.

Le Floch A. , Ropars G, Enoch J. and Lakshminarayanan V. (2010) The polarization sense in human vision. Vision Research. 50, 2048-2054.

Reich P. and Downes B. J. (2003) Experimental evidence for physical cues involved in oviposition site selection oflotic hydrobiosid caddis flies. Oecologia, 136,465-475.

Roldan-Carmona C. ,. Giner-Casares 1. 1. , Perez-Morales M. , Martin-Romero M. T. and Camacho L. (2012) Revisiting the Brewster Angle Microscopy: The relevance of the polar headgroup. Advances in Colloid and Interface Science, 173, 12-22.

Shibayev P and Pergolizzi R. G. (2011) The effect of circularly polarised light on the growth of plants. International Journal of Botany, 7, 113-117.

Stevani C. V., Porto J. S. , Trindade D.1. And Bechara E. J. H. (2000) Mechanism of automotive clearcoat damage by dragonfly eggs investigated by surface enhanced Raman scattering. Polymer Degredation and Stability, 68, 61-66.

Turcsanyia I. , Szentkiralyib F. , Bernathb B. and Kada rb F. (2009) Flight of mayflies towards horizontally polarised and unpolarised light. Aquatic Insects, 31, 301-310.

Wildermuth H. and Horvat G. (2005) Visual deception of a male Libellula depressa

by the shiny surface of a parked car (Odonata: Libellulidae). International Journal of Odonatology, 8, 97-105.

Welcome: What is Functional Biology?

By Dr Mike Wride

Functional Biology Course Director

 

Welcome to the Functional Biology, Trinity College Dublin blog pages for prospective, current and past Functional Biology TCD students and anyone else interested in Functional Biology. Here you will find blog articles written by Functional Biology staff and students.

 

The Functional Biology course at Trinity College Dublin focuses on comparing and contrasting the comparative physiology of plants and animals and other organisms (e.g. parasites) by comparing the way different kinds of organisms develop through embryogenesis and beyond and how physiological function depends on tissue and organ structure (anatomy). 

Many of the mechanisms organisms use for survival are conserved across species, allowing the revelation of key functional principles. Furthermore, the physiological mechanisms organisms have evolved depend on their interactions with the environment through time. Moreover, Functional Biology has important roles to play in elucidating the effects of gene mutations and/or deletions affecting protein function and environmental effects on gene expression and epigenetics (heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence).

The Junior Sophister (Third) year provides a broad knowledge and understanding of Functional Biology, while in the final year a major component of the course is a research project chosen in Plant Science or Zoology. Final year teaching also occurs through small group tutorials in areas of specialization in plant or animal Functional Biology as well as through lectures.

Functional Biology acts as an excellent springboard for undergraduate students to go on to post-graduate Bioscience degrees; e.g. Masters and PhDs in biological/physiological disciplines. Graduates of Functional Biology are also ideally placed to contribute to the knowledge economy/society through careers with biotechnology companies and/or industry, having gained unique and valuable experience and training. The course also provides an excellent background for students who want to pursue a career in teaching biology. Furthermore, our students gain a wide portfolio of transferable skills of importance to employers - written and oral presentation skills, group/team work, effective time management, data handling, computer literacy etc. Recent graduates include those who are undertaking Masters degrees in biological disciplines and business/commerce, working for banks, doing web design, working for pharmaceutical companies and are involved in public science and society and educational outreach work, to highlight just a few.

 

Functional Biology started within the Science Course TR071 at Trinity College Dublin in 2010 and the first 10 students completed their BA (Mod) Functional Biology degrees in 2012. Functional Biology is taught jointly by the Disciplines of Botany and Zoology from The School of Natural Science with additional input from the School of Genetics and Microbiology.

For more information see:

http://www.naturalscience.tcd.ie/undergraduate/functional-biology.php

We are also on facebook:

http://www.facebook.com/FunctionalBiologyTCD