Environmental Factors and How It Changes The Phenotype - Case Study Example

CAN ENVIRONMENTAL FACTORS ACTING ON ORGANISMS LEAD TO INHERITED CHANGES IN PHENOTYPE IN DESCENDANT INTRODUCTION Environmental factors acting on organisms definitely lead to inherited changes in phenotype in descendant generations. It is evident from studies on the genome of various organisms right from E. coli that any mutation or change in the genetic make up of an organism is passed on to generations. Thus, it is important to understand and study the role of environmental factors in altering this genomic structure of an organism to actually see if these environmental factors lead to inherited changes. To study the role of these environmental factors, the factors must be identified, classified and justified. Any ecosystem is composed of Abiotic and Biotic components. The Abiotic components include the atmosphere, where air acts as a medium, lithosphere and hydrosphere. The nature of the response of the organisms to these Abiotic factors depends on the essential factors and limiting factors. The response is best explained rather by ecological theories like Liebig-Blackman Law of Limiting factors and Shelford's Law of Tolerance. The Biotic components are composed of the biotic community each with an ecological niche influenced by community evolution, succession, growth, regulation and interactions. The ecological genetics is thus, a product of interactions of organisms with these Abiotic and biotic factors with the elements of adaptation, natural selection and speciation largely influenced by the ecological dynamics of energy flow and biogeochemical cycles. Thus, inherited changes in a phenotype depends on gravity of these interactions and the potential of these factors to cause a genomic change or a mutation. It is worthy to mention the role of Ecological pollution as a potential and vital factor in this process of genomic change today. ECOLOGICAL POLLUTION AS A MUTAGENIC FACTOR Ecological pollution is one of the vital factors causing genomic changes or mutation, which is being carried through the generations. Thus, these pollutants act as potential mutagens. The pollutants as mutagens in the Abiotic components of the ecosystem in atmosphere, hydrosphere and lithosphere are further influenced by the biotic interactions and the ecological dynamics of energy flow. More than 65,000 chemicals are currently in use in U.K with which human beings come into constant contact. Many of these chemicals are harmful and pose a serious health hazard. Numerous chemicals have been designated as hazardous to biological system and these chemicals pose an occupational health hazard to workers who are constantly in contact with them. These chemicals are often toxic, mutagenic/carcinogenic, causing serious diseases like Cancer and disabilities of various kinds. Even children born to women working in nickel refinery have been found to have Genital malformations. Industrial units that release toxic gases like Sulphur di oxide, Nitrogenous compounds and Mercurial derivatives contribute to air pollution to a great extent. The automobile exhaust fumes rich in carbon monoxide harms the oxygen binding mechanism in human blood. Welding is another industrial important contributor in which metal or other thermoplastic materials are joined together by the application of heat or pressure. This process produces gases like acetylene, carbon monoxide, oxides of nitrogen, ozone, phosgene and tungsten. (Palmer .T, 2006) The gas and chemical pollutants primarily enter the human system by inhalation route namely Respiration. The deposition of these inhaled particles in the lungs is influenced by its physical and chemical properties and a variety of host factors. In the lungs, these particles produce a variety of reactions including Asthma and Cancer depending on the concentration, duration of the exposure of the particles, and degree of exposure. Even babies in the womb have been found to be susceptible than their mothers to DNA damage from air pollution, despite the added protection of the placenta. The alarmingly high number of genetic mutations reported in the babies of New York have been linked the mutations to emissions from vehicles and other sources of urban pollution. A recent study of 265 pairs of nonsmoking African-American and Latina mothers and newborns in New York City at the time of delivery have shown that mothers and newborns had the same level of DNA damage from air pollutants. It is possible to measure the level of DNA damage from air pollutants in mothers and newborns by analyzing stretches of mutated DNA, called biomarkers that have been associated with exposure to diesel emissions and other air pollutants. (Pereira, et al., 2004). Attention is drawn today towards the Non-coding DNA sequences that seem to give rise to active RNAs, through which they profoundly alter the behavior of normal genes. Enough research studies have been carried out on the epigenetic layer of information stored in the proteins and chemicals that surround and stick to DNA (Gibbs et.al, 2003). Water pollution is another area of great concern. There is a lot of research in the areas of eutrophication in freshwater and marine environment. Legislations aimed directly at nitrate levels include the Surface Water Abstraction Directive, the Urban Waste Water Treatment Directive and the Nitrates Directive. The Nitrates Directive (91/676/EEC) is a Council Directive of 12 December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources and has the objective of reducing water pollution caused or induced by nitrates from agricultural sources and preventing further such pollution, with the primary emphasis being on the management of livestock manures and other fertilizers. The Water Pollution Acts, 1977 and 1990 and regulations made there under, including regulations giving effect to EU Directive, constitute the main national legislation in this regard. The most serious pollution problem in aquatic ecosystem is Eutrophication and dilution of toxic industrial waste into aquatic environments like rivers and lakes. Eutrophication can be understood as the enrichment of an ecosystem with chemical nutrients like nitrogen or phosphorus from agricultural and domestic run off. (Anderson, 1997). There are serious ecological impacts due to such pollutants like, decreased biodiversity, changes in species composition, dominance, and toxicity effects. These toxic compounds find their way up the ecological food chain. An example of algal toxins finding their way into humans is the case of shellfish poisoning (Shumway 1990). Biotoxins created during algal blooms are taken up by shellfish (mussels, oysters), causing paralytic, neurotoxic, and diarrhoetic shellfish poisoning in human beings. Other animals act as vectors for such toxins, as in the case of ciguatera, a predator fish that accumulates the toxin and then causes human food poisoning. CHRONIC EXPOSURE - A CRUCIAL FACTOR IN MUTATION Changes in the genome to the level of being carried on to generations seems to be more due to a chronic or prolonged period of exposure rather than a short time or acute exposure to these ecological factors like pollution. This is due to the fact that the genome of every organism is equipped with an inherent DNA repair mechanism, which effectively combats and rectifies any changes in the sequence caused by these factors. A genomic change occurs even to the level of a point mutation only at the point when the mutagens damage the gene mechanism beyond this limit. This often happens only when the toxic concentrations are high and the cells are exposed to these toxic mutagens over a period of time. Recent studies on 27 welders with long-term exposure to welding metal fumes revealed a reversible increase in the risk of Pneumonia. In the sputum, cell counts, soluble levels of the metal, levels of Interleukin-8, tumour necrosis factor-, myeloperoxidase, metalloproteinase -9, Immunoglobulin (Ig)A, 2-macroglobulin and unsaturated metal binding capacity were analyzed and in the blood samples, evidence of neutrophil activation and IgG pneumococcal antibodies were analyzed. The studies concluded that the local inflammatory response was affected by chronic exposure (Palmer, 2006). This chronic exposure, as discussed, has serious ecological impacts like decreased biodiversity due to elimination of those species or organisms that cannot adapt genetically to the mutagens; changes in species composition due to competent organisms or those organisms that can adapt to invade and establish an ecological niche; causing species dominance affecting the equilibrium of an ecosystem and ecological genetics which depends on adaptation, natural selection and speciation. CONCENTRATION -YET ANOTHER FACTOR IN MUTATION In a circular numbered 71/2002, The Health and safety Executive (HSE), UK published revised COSHH (the control of substances hazardous to Health) regulations. These COSHH 2002 regulations came into force from 21 November for hazardous substances and includes control measures for hazardous substances. The risk assessment includes the properties of the chemical, health effects, the exposure limits, preventive and control measures, health surveillance, monitoring and other additional information needed. For example, the Occupational exposure limits for Aluminium has been assigned as 5mg/m and the chemical falls in UN hazard class: 4.3.Thus, every pollutant has an concentration limit beyond which it causes harm to organisms exposed to it. The role of Biological Magnification of such ecological mutants in mutation is worth mentioning. Biological Magnification is a process where toxic substances released into the ecosystem get accumulated in minute quantities in the biotic factors and are magnified in the process of food chain .For example, the algal phytoplankton in an aquatic ecosystem absorbs minute quantities of the pollutants over a period of exposure. The zooplankton in the same ecosystem accumulate these mutagens in higher concentrations while feeding on the phytoplankton. The fishes feeding on the zooplankton accumulate still higher concentrations of the mutagens. Thus, the mutagens reach toxic concentration levels or mutagenic levels at the end of the food chain. CONCLUSION Environmental factors acting on organisms definitely lead to inherited changes in phenotype in descendant generations because of the simple fact that these ecological factors are potent mutagens which can effect a change in the genome of the organisms and these genomic changes will affect the equilibrium of the ecosystem. Works Cited: Anderson, D. M. & Garrison, D. L.. "The ecology and oceanography of harmful algal blooms: preface". Limnology and Oceanography, 1997,42, 1007-1009. Balls, P. W. "Nutrient inputs to estuaries from 9 Scottish east-coast rivers - influence of estuarine processes on inputs to the North Sea." Estuarine Coastal and Shelf Science,1994, 39, 329-352. CSTT (1997). Comprehensive studies for the purposes of Article 6 & 8.5 of DIR 91/271 EEC, the Urban Waste Water Treatment Directive, second edition. Gillbricht, M. Phytoplankton and nutrients in the Helgoland region. Helgolander Meeresuntersuchungen, 1988, 42, 435-467. Gowen R.J.;Hydes D.J.;Mills D.K;Stewart B.M.;Brown J;Gibson C.E;Shammon T.M;Allen M.;Malcolm S.J., "Assessing Trends in Nutrient Concentrations in Coastal Shelf Seas: a Case Study in the Irish Sea", Estuarine, Coastal and Shelf Science, Volume 54,Number 6, June 2002, pp. 927-939(13). Grantham, B. & Tett, P. The nutrient status of the Clyde Sea in winter. Estuarine, Coastal & Shelf Science, 1993, 36, 449-462. Gibbs, W. Wayt .The Unseen Genome: Beyond DNA., Scientific American, Dec2003, Vol. 289, Issue 6 http://lepo.it.da.ut.ee/olli/eutr/html/htmlBook_0.html- Paul Wassmann and Kalle Olli, "Drainage basin nutrient inputs and eutrophication: an integrated approach", Version - September 2, 2004. http://www.agu.org/meetings/os06/os06-sessions/os06_OS11C.html http://www.defra.gov.uk/environment/water/marine/uk/science/irishbristol/07.htm http://www.fwr.org/eutrophi/eapost97.htm- K Kennington, JR Allen, TM Shammon, RG Hartnoll, A Wither and P. Jones, Environment Agency- R&D Technical Report E55 http://www.liv.ac.uk/isf1/isfhome.html http://www.liv.ac.uk/isf1/semsums/sem31sum.html. http://www.offshore-sea.org.uk/site/scripts/downloads.phpcategoryID=13 http://www.sos.bangor.ac.uk/research/MATSIS/index.html J. O'Sullivan, "Ecological Effects of Sewage Discharge in the Marine Environment", Proceedings of the Royal Society of London. Series B, Biological Sciences, Vol. 177, No. 1048, A Discussion on Biological Effects of Pollution in the Sea (Apr. 13, 1971), pp. 331-351. J. R. Allen, D. J. Slinn, T. M. Shammon, R. G. Hartnoll, S. J. Hawkins, "Evidence for Eutrophication of the Irish Sea Over Four Decades", Limnology and Oceanography, Vol. 43, No. 8 (Dec., 1998), pp. 1970-1974.. Joint, I., Lewis, J., Aiken, J., Proctor, R., Moore, G., Higman, W. & Donald, M. Interannual variability of PSP outbreaks on the north east UK coast." Journal of Plankton Research, 19, 937-956. 1997. Jones, K. J., Ayres, P., Bullock, A. M., Roberts, R. J. & Tett, P. "A red tide of Gyrodinium aureolum in sea lochs of the Firth of Clyde and associated mortality of pond-reared salmon." Journal of the Marine Biological Association of the United Kingdom, 62, 771-782.1982. K.Kennington, J.R.Allen, A.Wither, T.M.Shammon and R.G.Hartnoll, "Phytoplankton and nutrient dynamics in the north-east Irish Sea", Hydrobiologia , Volume 393, Number 0 / January, 1999.. Lancelot, C., Billen, G., Saurian, A., Weisse, T., Colijn, F., Veldhuis, M. J. W., Davies, A., et al. "Phaeocystis blooms and nutrient enrichment in the continental coastal zones of the North Sea". Ambio, 16, 38-46. 1987 Larsson, U., Elmgren, R. & Wulff, F. "Eutrophication and the Baltic Sea - causes and consequences". Ambio, 14, 9-14.1985. Palmer .T. et. al: Inflammatory responses to the occupational inhalation of metal fume, Eur Respir J, 27: 366-373, 2006. Perera, F.P. et al. Biomarkers in maternal and newborn blood indicate heightened fetal susceptibility to procarcinogenic DNA damage. Environmental Health Perspectives 112, 1133-1136 (July 2004). Raffaelli, S., Limia, J., Hull, S. & Pont, S. "Interactions between the amphipod Corophium volutator and macroalgal mats on estuarine mudflats". Journal of the Marine Biological Association of the United Kingdom, 71, 899-908. 1991. T.M.Shammon and R.G.Hartnoll, "The winter and summer partitioning of dissolved nitrogen and phosphorus. Observations across the Irish Sea during 1997 and 1998", Hydrobiologia, Volume 475-476, Number 1 / May, 2002.. Tett, P. & Edwards, V. (2003). Review of harmful algal blooms in Scottish coastal waters. Report, SEPA, Stirling. Obtainable from: SEPA web-site. Tett, P. & Wallis, A. "The general annual cycle of chlorophyll standing crop in Loch Creran." Journal of Ecology, 66, 227-239. 1978. Tett, P., Gowen, R., Grantham, B., Jones, K. & Miller, B. S. "The phytoplankton ecology of the Firth of Clyde sea-lochs Striven and Fyne", Proceedings of the Royal Society of Edinburgh, 90B, 223-238. 1986. W. H. Pearsall, "A Suggestion as to Factors Influencing the Distribution of Free-Floating Vegetation", Journal of Ecology, Vol. 9, No. 2, pp. 241-253. Feb., 1922. Read More