Parasite-Induced Changes in Host Behaviour

Parasite-Induced Changes in Host Behaviour Parasite-Induced Changes in Host Behaviour: Is it Truly Parasitic Manipulation? Introduction Behavioural changes in the host when infected with a parasite were first observed in 1952, when van Dobben discovered that fish caught by cormorants (waterbird) were more likely to play intermediate host to the cestode, Ligula intestinalis than fish caught by fishermen (cited in Thomas et al., 2005). However it wasn’t until 1972 that the ability of parasites to manipulate their host’s behaviour in order to facilitate their transmission was discovered and demonstrated by Holmes and Bethel (cited in Poulin, 2000). They showed that infection of the parasite, Polymorphus paraoxus caused the amphipod, Gammaeras lacustris to display abnormal behaviours that led to an increase in its predation by ducks, the definitive host of the parasite. Since then there has been considerable research carried out in this area supporting the idea that parasites have adapted in order to manipulate their host, with a large number of parasites now known to cause changes to their hosts behaviour. There is a wide array of influenced behaviours from anti-predator behaviour e.g. mice infected with the tapeworm, Taenia crassiceots show no stress response to predation (Wheat, 2009); to reproductive behaviour e.g. female mice infected with the nematode, Trinchinella spiralis show inhibition of their sexual behaviours, limiting possible mate response (Kavaliers et al., 2000). In a few cases completely new behaviours in infected hosts have been observed, for example orb-weaving spiders infected by a parasitic wasp build unusual webs that are designed to protect the emerging larva once the host spider dies (Eberhard, 2010). More recently, the idea of parasitic manipulation has come under criticism, due to the lack of supporting evidence demonstrating that these behavioural changes provide parasites with a fitness benefit (a prerequisite of an adaptive trait), either in the form of increased transmission or survival (Poulin, 1998) and has therefore been suggested that the observed ch anges may just be an inevitable consequence of infection, or in some cases mediated by the host itself in order to counteract the negative fitness effects of parasitic infection. Understanding the origin of these behavioural changes is of great importance as there are many manipulative parasites that have implications for human health, such as malaria which alters the behaviour in the mosquito in order to increase transmission to humans (Lynch et al., 2014) and Toxoplasma gondii which can alter the personality of infected individuals (Worth et al., 2014). Manipulative parasites are also seen as playing as important a role as predation in shaping biological communities, even having an influence on non-host species (Hatcher et al., 2014). Adaptive vs. Non-adaptive Behavioural Change The argument that some of the previously observed behavioural changes of the host during parasitic infection are non-adaptive and just a consequence of infection generally refers to three different kinds of phenomena (Thomas et al., 2005). The first is the idea that the behavioural changes are just a side-effect of parasitic infection and confer no adaptive value for either the parasite or its host. However this is a questionable explanation as it is highly unlikely that any such change in behaviour will not provide a positive effect for either organism. Therefore this explanation should only be used if there is strong supporting evidence and not used as a default explanation, for example the parasitic cestode, Hymenolepis diminuta was shown to cause reduced fecundity in females of the beetle intermediate host, Tenebrio molitor and was seen as a side-effect, until further research discovered that the parasite produced a substance that inhibited vitellogenin uptake (Moore, 2012). Seco ndly some behavioural changes may be considered beneficial to the parasite, but are not due to manipulation by the parasite in order to do so, for example when the parasite Ligula intestinalis infects the Roach (Rutilus rutilus) a change in host migration to areas where predation by the parasites definitive host, ichtyopahgous predatory birds, are more common is observed (Loot et al., 2001). However it was found that these areas are more productive and it is therefore more likely that the increased energy demands caused by the parasitic infection had caused the Roach to migrate to these areas in order to negate this negative effect of the parasitic infection and increase its own fitness. Thirdly other adaptations by the parasite may have coincidentally caused behavioural changes in the host which unintentionally led to an increase in the transmission of the parasite to its definitive host, for example Fathead minnows (Pimephales promelas) are commonly infected by the trematode, Orni thodiplostomum ptychocheilus which caused a reduction in behaviours associated with host vision by the encystment of the parasite in the optic lobes, which leads to an increase in its predation by piscivorous birds. However this encystment in the eye may originally been favored by selection as it offers the parasite protection from the host’s immune system and not because it increased the transmission of the parasite to its definitive host (Shirakashi and Goater, 2005) On the other hand the argument for the adaptive nature of behavioural changes of the host during parasite infection is normally supported by the idea that it should show some degree of specificity in the intermediate host, for example P. laevis induces various behavioural and physiological changes in the crustacean amphipod, Gammarus pulex, such as altered drifting behaviour, altered anti-predator behaviour, partial castration and lower immune activity. These changes are not observed in Gammarus roeseli a closely related species, showing that the alterations by the parasite are specific to Gammarus pulex (Lagrue et al., 2007) Examinations on the effect of the acanthocephalan parasite, Moniliformis moniliformis on the behaviour of different species of cockroaches by Moore and Gotelli found that different behavioural changes had evolved for different species of cockroach supporting the adaptive nature of the host behavioural change (cited in Poulin, 1998). Indirect methods have also be en used to demonstrate the adaptive nature of altered behaviours in the host by determining whether the timing of observed behavioural changes coincide with the period when the parasite is infective to its next host. For example Tribolium confusum beetles infected with the nematode, Protospirura muricola only show observable changes in the behaviour of the beetles that make them more vulnerable to predation when the parasite has developed to the third larval stage. No behavioural change is observed in beetles home to the first and second larval stage. (Schutgens et al., 2013) Behaviour as a Form of Host Defense Not all changes in behaviour can be attributed to the manipulation of the host by the parasite as they do not benefit the parasite. The host is under selection to avoid parasites, and when possible to compensate for the negative effects of infection. Behaviour is often used in order to achieve this and is the first line of defence against parasites as it allows animals to avoid becoming infected in the first place (Moore, 2012). Animals may avoid infection by parasite propagules through behavioural means such as territoriality, site-specific defecation and mate selection. More drastic measures may be taken when trying to avoid ectoparasites, including migration, shifting habitats and lethal combat e.g. howler monkeys invest a significant proportion of their energy to slap at flies, and execute over 1500 slaps in a 12 hour resting period. Once a host becomes infected with a parasite, its behaviour will also be altered in order to minimise damage caused by the parasite. For example ani mals display sickness behaviours e.g. fever and behavioural chills, which may help in obtaining the benefit of increased care from other members of a group/population. Some animals, for example Chimpanzees, show self-medicating behaviour in which infected animals may consume medicinal plants that are not part of their usual diet. It is also possible in some cases that both parasite and host are shown to benefit from a change in host behaviour, in these cases it can be difficult to determine which organism is responsible for change, or whether it is a shared adaptation, for example caterpillars of several butterfly species play host to braconid wasp parasitoids and unlike non-parasitised individuals they perch at the top of high branches. It has been suggested this benefits the host by making itself more likely to eaten by a predator, killing both the parasitoid and host, but protecting its nearby relatives from the parasite. However it may also help the parasite by reducing the risk of hyperparasitism and therefore increasing its chance of survival. (Poulin, 1998). Conclusion Up to this point mainly laboratory based studies have been carried out in order to assess host behavioural changes due to parasite infection. Future research into the area needs to include field based studies in order to fully assess these changes in the natural environment. Currently very little is known about the molecular and genetic mechanisms underlying these changes. Therefore the basis as to how parasites cause these behavioural changes in there host is an area that needs to be addressed in order for these behavioural changes to ever be fully understood. Word Count: 1490 References Thomas, F., Adamo, S. and Moore, J. 2005. Parasitic manipulation: where are we and where should we go? Behavioural Processes, 68: 185-199 Poulin, R. 2000. Manipulation of host behaviour by parasites: a weakening paradigm? Proceedings of the Royal Society Biological Sciences, 267 (1445): 787-792 Wheat, S. E. B. 2009. Parasitic manipulation: The current state and future direction. University of Sheffield, Department of Animal and Plant Sciences Kavaliers, M., Colwell, D. D. and Choleris, E. 2000. Parasites and behaviour: An ethopharmacological perspective. Parasitology Today. 16 (11): 464-468 Eberhard, G. W. 2010. New types of behavioural manipulation of host spiders by a parasitoid wasp. Psyche: A Journal of Entomology. 2010: 1-4 Poulin, R. 1998. Evolution and phylogeny of behavioural manipulation of insect hosts by parasites. Parasitology. 116: S3-S11 Cator, L. J., Lynch, P. A., Thomas, M. B. and Read, A. F. 2014. Alterations in mosquito behaviour by malaria parasites: potential impact on force of infection. Malaria Journal. 13(164) Worth, A. R., Lymbery, A. J. and Thompson, R. C. A. 2013. Adaptive host manipulation by Toxoplasma gondii: fact or fiction? Trends in Parasitology. 29(4): 150-155 Hatcher, M. J., Dick, J. T. A. and Dunn, A. M. 2014. Parasites that change predator or prey behaviour can have keystone effects on community composition. Biology Letters. 10: 20130879 Moore, J. 2012. An overview of parasite-induced behavioural alterations – and some lessons from bats. The Journal of Experimental Biology. 216: 11-17 Loot, G., Brosse, S., Lek, S. and Guegan, J. F. 2001. Behaviour of roach (Rutilus rutilus L.) altered by Ligula intestinalis (Cestoda: Pseudophyllidea: a field demonstration. Freshwater Biology. 46: 1219-1227 Shirakashi, S. and Goater, C. P. 2005. Chronology of parasite-induced alteration of fish behaviour; effects of parasite maturation and host experience. Parasitology. 130: 177-183 Lagrue, C., Kaldonski, N., Perrot-Minnot, M. J., Motreuil, S. and Bollache, L. 2007. Modification of hosts’ behaviour by a parasite: field evidence for adaptive manipulation. Ecology. 88(11): 2839-2847 Schutgens, M., Cook, B., Gilbert, F. and Behnke, J. M. 2013. Behavioural changes in the flour beetle Tribolium confusum infected with the spirurid nematode Protospirura muricola. Journal of Helminthology. 1-12

Free Waste Land Essays: A New Understanding :: T.S. Eliot Waste Land Essays

The Waste Land: A New Understanding The Waste Land, Eliot's first long philosophical poem, can now be read simply as it was written, as a poem of radical doubt and negation, urging that every human desire be stilled except the desire for self-surrender, for restraint, and for peace. Compared with the longing expressed in later poems for the "eyes" and the "birth," the "coming" and "the Lady" (in "The Hollow Men," the Ariel poems, and "Ash-Wednesday"), the hope held out in The Waste Land is a negative one. Following Hugh Kenner's recommendation, we should lay to rest the persistent error of reading The Waste Land as a poem in which five motifs predominate: the nightmare journey, the Chapel, the Quester, the Grail Legend, and the Fisher King. The motifs are indeed introduced, as Eliot's preliminary note to his text informs us, but if (as this note says) "the plan and a good deal of the incidental symbolism of the poem were suggested by Miss Jessie L. Weston's book on the Grail legend," the plan can only have been to ques tion, and even to propose a life without hope for, a quest, or Chapel, or Grail in the modern waste land. The themes of interior prison and nightmare city--or the "urban apocalypse" elucidated by Kenner and Eleanor Cook--make much better sense when seen as furnishing the centripetal "plan" and "symbolism," especially when one follows Cook's discussion of the disintegration of all European cities after the First World War and the poem's culminating vision of a new Carthaginian collapse, imagined from the vantage point of India's holy men. A passage canceled in the manuscript momentarily suggested that the ideal city, forever unrealizable on earth, might be found (as Plato thought) "in another world," but the reference was purely sardonic. Nowhere in the poem can one find convincing allusions to any existence in another world, much less to St. Augustine's vision of interpenetration between the City of God and the City of Man in this world. How, then, can one take seriously attempts to find in the poem any such quest for eternal life as the Grail legend would have to provide if it were a continuous motif--even a sardonic one? It seems that only since Eliot's death is it possible to read his life forward--understanding The Waste Land as it was written, without being deflected by our knowledge of the writer's later years.

Critical Review for the Article Essay

The electronic journal entitled: ‘The Long-Term Performance of Horizontal Acquisition’, by Laurence Capron of the Institut Europeen d’Administration des Affaires (INSEAD), published in 1999 by the Wiley and Sons publishing, has studied the creation of â€Å"horizontal mergers and acquisition†. In Capron’s paper, he dated his studies from mid-1980’s to early 1990’s financing strategies of firms in divesting and liquidating its assets which he referred as the â€Å"horizontal mergers and acquisition†. Capron has cited about 253 firms in Europe and America that patterns the financing strategies. According to Capron (1999), examination reveals divestment of assets and capital infusion (re-financing of liquidated assets) makes effective to â€Å"acquisition performance†, but could have potentially detrimental impact. As what Capron emphasized on the performance of acquisition based on â€Å"divestment and redeployment (re-acquisition) of resources†, his study examines the defects and compliments on effective means in â€Å"horizontal mergers and acquisition†. Key points and rationale As reviewed from the journal, the â€Å"horizontal acquisitions† may be exemplified as a means and strategy in establishing the resource-divestment scheme, in which by doing so, it â€Å"optimizes or exploits the values of cost-based and revenue-based synergies† (Capron 1999: p. 988). As explained, it may be perceived that the â€Å"synergy† patterns the continuing acquirement of business values, as a result of divestment wherein merging of the newly diversified firm or business values acquires more assets and capital budget. According to Capron (1999), the cost efficiency theory emphasizes on the significance of cost-based synergies that occur when assets have been divested resulting the integration of cost-saving measures. Thus, the firm performs effectively in enhancing its revenues that synergizes with the redistribution of the capital towards an enhanced capability. It may be analyzed from the findings of Capron that the 1980’s and 1990’s rapid growth of industries brought about by globalization have emerged more investments in the supply chain. One of which is the positioning of developed and high-end industries within raw material sources. Like, for example, diversification process has been developed in Asian countries wherein more investment in cheap raw materials and labor are available and can be acquired easily. The â€Å"horizontal acquisition† could be drawn from establishing partnership, subsidiary in operation, joint ventures and inter-dependency in export and import schemes. Hence, for example â€Å"Company A† has divested in establishing â€Å"Company B† to engage in tire manufacturing that source out the cheapest raw materials. In which case, a diversified industrial firm could venture out into â€Å"versatile† business values that optimize capital investments for a larger revenue generation translated into cost effectiveness that means substantial profitability. In Capron’s finding, the so-called â€Å"economy of scale† became the bases of diversification process that paved the way to a â€Å"large-scale† industrialization. The 20th century practice of the economy of scale has favored more industries to capture the â€Å"investment areas†, specifically in poor countries. The â€Å"dispensation of merging† through open-ended stockholding in small-medium-large enterprises units has put significant relevance in acquiring industrial partnership, wherein capital investment has a critical role in merging companies. As cited from Capron’s findings, the logical economic explanation is capturing revenue-based synergies which are commonly identified as allocating and complementing resources by providing â€Å"core competencies† or â€Å"mobilizing invisible assets† (Penrose 1959; in Capron 1999: p. 989). As cited, Capron also pointed out in his â€Å"theoretical model† of post-acquisition and target redeployment (Capron 1999: pp. 990-995). According to Capron, the theory describes the diversification process as focusing on (1) asset divestiture, (2) cost-saving, (3) resource redeployment, and (4) revenue-enhancing capabilities as an effective means of â€Å"acquisition performance† (Capron 1999: p. 992). The theoretical model refers to and explains the â€Å"basic economic behavior† as outlined in the acquisition performance. Capron further theorized that capabilities in a divested firm are being distributed as an organizational undertaking. Meaning, it can be explained that the system of corporate governance and human resources are distributed or being shared that composes the acquisition performance. However, key â€Å"organic elements† were emphasized to have been integrated in the divestment process, in which the re-deployment (or deployment) of the organizational â€Å"system or setting† are acquired. Conclusion Capron’s examination on the horizontal acquisition and projection of model in strategic post-acquisition and redeployment could be understood as a fundamental undertaking in diversification process. It may be true that most of merging firms in their acquired assets or business are mainly distributing their in-placed â€Å"organizational or corporate system†. However, the merging firms could likewise optimize or â€Å"streamline the existing organizational set-up, which is the common occurrence in most firms that undertaken a â€Å"buy-out†. It may be perceived that the revenue-generation could be largely acquired into options by streamlining the existing organizational set-up or re-organizing both human and capital resources. Capron’s findings have emphasized more on the performance capability on the theory of â€Å"horizontal acquisition† referring only to capital budget, as implied on the capital resources or fixed assets of the firms. The human resource aspect [as a critical unit] of the post-acquisition process may have not been well emphasized. What has been generally discussed in the study is the transformative business value in divestment schemes referring to capital investments and fixed asset liquidation. It could be reflected that the capital investment and fixed asset liquidation are the critical factors in the divestment schemes as the primary resource of merging stakeholder. It could be suggested that the â€Å"potentially detrimental impact† [as also pointed out by Capron] could be referred to the human resources or labor force in a diversified industry. The merging stakeholder in Capron’s findings were much given relevance on how they could effectively perform in targeting their post-acquisition and redeployment, in which the study itself envisions to complement the performance capabilities of the stakeholders. At this point, we may re-examine Capron’s â€Å"theoretical model† as giving more â€Å"weight† to the envisioning of transnational and multi-national enterprises in furtherance of globalization, in which the continuing divestment scheme competes in the large scale economy of labor market and capital build-up. We may then conclude that Capron’s findings could be re-examined with further studies relating to human resources re-deployment or deployment on its horizontal development complementing the diversification of industries, in which the parallelism envisions both human and capital divestment. Section B Morrison’s bid to Safeway The electronic magazine of the Financial Times on its December 8th 2003 issue at the www. ft. com web site has published the news article of Richard Milne entitled: ‘Countdown Starts for Morrison’s Bid for Safeway’. According to the news article, the Morrison Supermarket bided 21 days from its competitors, such as Tesco, J. Sainsbury and Asda-WalMart, following the UK government’s offer to sell the Safeway supermarket. The UK Department of Trade and Industry disclosed that â€Å"Morrison was willing to sell its 53 stores if acquisition of Safeway is successful† (Richard Milne 2003; in Ft. com 2008). Morrison’s negotiation was favored by the UK Competition Commission that disqualified the three major competitors from the bidding and upheld Morrison to takeover Safeway with a share of 219-1/2 from the 279-1/2, in which Safeway acknowledged the buy out. In a follow up report in 2004, after a year of the buy out, the Safeway has gained 40% of sales growth. Financial analysts claimed that Safeway has â€Å"migrated customers† to Morrison supermarket, as it cited that â€Å"quality of sales has gone better because Morrison has stopped the Safeway policy of rolling deep discounts† (Martin Dickson 2004; in Ft. com 2008). Perception of the issue Morrison’s takeover of Safeway supermarket has gauged the situation of significant financial divestment venture. The business potentials of Safeway [being an established supermarket that solely competes with Tesco, J. Sainsbury and Asda-WalMart] were the â€Å"strong intent† of financial divestment of Morrison to even offer the sell of its 53 stores. The financial divestment of Morrison could be relating Capron’s findings on the â€Å"horizontal acquisition† of merging stakeholders by way of capital investments through diversified assets. In which case, the Safeway supermarket has found by Morrison as a â€Å"potential divestiture† that shall absorb the vulnerability from tough competitors. The merging of stakeholder through a buy-out or takeover of an established investment [like Safeway] may have validated Capron’s theory of â€Å"post-acquisition and redeployment†, in which Morrison has able to â€Å"contain† the migratory customers and could further develop the acquisition performance of divesting financial investments. The divestment process of Morrison’s takeover to Safeway has likewise described Capron’s finding on merging firms that engages in the economy of scale. One that Morrison has learned from the Safeway’s enterprise approach on rolling deep discounts, wherein it found to be defeating the â€Å"selling schemes†. Thus, managing the risks in â€Å"horizontal acquisition† has gained Morrison’s capability to undertake strategic competition that transformed the â€Å"old Morrison business† through the new outfit of Safeway supermarket. It may be then generally perceived that Capron’s theory on â€Å"horizontal acquisition† has transformative business value in enhancing the financial investment and liquidating a frozen asset [like Morrison’s 53 stores that are non-performing], of which a â€Å"unilateral† financial divestment scheme in managing risk investment, that is vulnerable to tightened competition, gains flexibility upon acquiring an established business venture. However, this assumption is perceptive of a challenge to the continuing financial divestment of core industries in the global market. List of References Capron, L. (1999) ‘The Long-Term Performance of Horizontal Acquisition’. Strategic Management Journal, pp. 987-1018, John Wiley & Sons, Ltd. , CCC 0143– 2095/99/110987–32. Dickson, M. (2004). ‘Companies UK: Safeway Sale’. The Financial Times (2008). [online] available from

Compulsory Rotatory Internship Programme ( Crip ) And The...

Long working hours and stressful working environment along with the immense pressure of impending PG entrance exam hinder the affectivity of the Compulsory Rotatory Internship Programme (CRIP). Our study is an attempt to find the views regarding Compulsory Rotatory Internship Programme (CRIP) and the preferred post graduate specialities among interns from NKP Salve Institute of Medical Sciences and Research Center, Nagpur. METHOD A descriptive cross-sectional study was conducted; the questionnaire was well structured and was developed after reviewing the literature extensively. The study was conducted after approval from the Institutional Ethical Committee of NKP Salve Institute of Medical Sciences Research Center, Nagpur. Part I: Eighty nine interns who had completed one year rotating internship programme at NKPSIMS RC were enrolled in the study. Data was collected with the use of pretested semi structured proforma. This was including questions regarding socio-demographic pro le, preference for the specialty, factors responsible for the selection of particular branch and perceptions about working in rural areas. Interns were allowed to choose only one answer in each question. Data was collected and entered into spreadsheet of MS Excel. Later on it was analyzed with the use of Epi-Info software. Part II: Focus group discussion (FGD) was held with these interns in batches of 10. Set of discussion topics were used for the FGDs were skill development, facilities during