The ecology and evolution of malaria: Laboratory studies of <i>Plasmodium chabaudi</i> and its rodent and insect hosts

In this thesis I investigated selective pressures that could shape the ecology and evolution of the malaria parasite and its mosquito host. I used the rodent malaria parasite Plasmodium chabaudi, laboratory mice and the lab adapted malaria vector Anopheles stephensi. Key theory underpinning much of this work is the virulence trade-off hypothesis, where virulence (harm to host) is thought to be an unavoidable consequence of the parasites effort to optimise fitness. Implicit in this theory is that virulence is an intrinsic parasite trait, so that a virulent parasite would be relatively virulent in all host types. Using four genetically distinct P. chabaudi clones and four distinct host strains I found for the most part, this assumption to be true; the virulence phenotype of each of the four parasites was the same across the four host strains tested. I further used these genetically distinct P. chabaudi clones along with candidate malaria vaccine AMA-1 to study 1) vaccine efficacy against single and mixed clone infections and 2) the potential selective effects of vaccination. I found that vaccination reduced parasite density in a strain specific manner and that diversity at loci other than the target antigen influenced vaccine efficacy. In both naive and vaccinated hosts, selection for increased virulence was observed in mixed genotype infections, but in no case did vaccination enhance this selective pressure. As Plasmodium evolution is intricately linked to vector population dynamics, I explored environmental conditions that may influence Anopheles fitness. Specifically, I investigated whether the amount of food Anopheles parents experienced influenced the success of their offspring. I found that the food level of both parents and offspring were important in Anopheles fitness. In particular, daughters from parents reared in low food conditions produced more eggs that daughters from parents reared in high food conditions. In sum, my results indicate that the within-host environment of the malaria parasite can act as a selective agent. In addition, the environmental conditions experienced by Anopheles larvae could impact vector population dynamics. Altering the within-host environment of the parasite or the environment of its vector could dramatically alter the ecology and evolution of the malaria parasite

The effect of parental rearing conditions on offspring life history in Anopheles stephensi

Background The environmental conditions experienced by parents are increasingly recognized to impact the success of offspring. Little is known on the presence of such parental effects in Anopheles. If present, parental effects could influence mosquito breeding programmes, some malaria control measures and have epidemiological and evolutionary consequences. Methods The presence of parental effects on offspring emergence time, size, survival, blood meal size and fecundity in laboratory reared An. stephensi were tested. Results Parental rearing conditions did not influence the time taken for offspring to emerge, or their size or survival as adults. However, parental effects were influential in determining the fecundity of daughters. Counter-intuitively, daughters of parents reared in low food conditions produced larger egg clutches than daughters of parents reared in high food conditions. Offspring reared in low food conditions took larger blood meals if their parents had also experienced a low food environment. Conclusion So far as we are aware, this is the first evidence of parental effects on progeny in Anophele

The ecology and evolution of malaria : laboratory studies of Plasmodium chabaudi and its rodent and insect hosts

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Sentencing snapshot: motor vehicle theft 2009-2010

This snapshot describes the penalties imposed on adult offenders convicted of motor vehicle theft. Over the period 2009 to 2010 a total of 1018 offenders were convicted of motor vehicle theft in NSW Local and District Courts. Imprisonment was the most commonly imposed penalty, followed by a bond without supervision and a suspended sentence. The risk of imprisonment increased with the number of prior convictions. In addition, offenders previously imprisoned for theft or a related offence were most likely to be sentenced to imprisonment for their current motor vehicle theft offence (92% and 79% respectively)

Crime on the NSW rail system

The rate of offending on both NSW trains and at stations is very low, however relative risk varies considerably depending upon location, day of week and time of day. The rail transport system is an integral part of the State’s urban infrastructure. Residents in the Sydney Statistical Division make approximately one million train trips on an average weekday. While this only accounts for five per cent of trips (most are made by car), it accounts for 13 per cent of the distance travelled and nearly 10 per cent of the time travelled on a typical weekday. Most train journeys occur without experiencing any form of crime. However, a number of passengers report concerns over personal security on one or more of their passenger journeys. For example, in 2008, 26 per cent of train users reported feeling threatened by the actions of other people on a train or at a station, 19 per cent reported witnessing or being a victim of criminal activity or violent behaviour, and 23 per cent of train users reported witnessing or being a victim of harassment or verbal abuse. While surveys such as these provide important information about the extent of victimisation on the rail system, surveys do not allow for detailed analysis of crime in particular locations or at particular times. Crime information recorded by the NSW Police Force allows for these sorts of comparisons. In 1994, the Bureau published a report detailing the spatial and temporal characteristics of recorded crime on the NSW rail system. The report attracted widespread public interest. The data reported in Jochelson’s report covered the early part of the 1990s and are now very out of date. The aim of the current report is to update Jochelson’s study to give a broad profile of recorded crime on the NSW rail system between the years 2001 and 2010. Image: emmettanderson / flick

Why does NSW have a higher imprisonment rate than Victoria?

The NSW imprisonment rate is about twice that of Victoria: this bulletin examines the influence of sentencing practice and other factors on the difference between NSW and Victoria in their imprisonment rates. The NSW imprisonment rate is about twice that of Victoria (204 per 100,000 population vs. 104 per 100,000 population) (Australian Bureau of Statistics, 2009a). This fact is widely believed to indicate that sentencing policy and practice in NSW is much harsher than in Victoria. A higher imprisonment rate, however, does not necessarily indicate tougher sentencing. The difference between the two states in their imprisonment rates may, for example, arise from differences in the rate of arrest for serious crime, differences in their bail laws or differences in their parole policies. Aim: To examine the influence of sentencing practice and other factors on the difference between NSW and Victoria in their imprisonment rates. Method: Descriptive analysis of national crime, court and prison data. Results: The NSW court appearance rate is 26 per cent higher than that in Victoria. The overall conviction rate in NSW is 85.7 per cent, compared with 79.0 per cent in Victoria. The overall percentage imprisoned is significantly higher in NSW (7.5%) than in Victoria (5.4%). The mean expected time to serve among prisoners dealt with by Victorian courts is slightly longer than the mean expected time to serve among prisoners dealt with by NSW courts. The NSW remand rate is approximately 2.5 times the Victorian remand rate. Conclusion: The higher NSW imprisonment rate is attributable to a higher rate of court appearance, a slightly higher conviction rate, a higher likelihood of imprisonment and a higher likelihood of remand in custody. Image: Summers / flick

2a: Summary graphs showing the main effect of i) Offspring food (low and high) ii) Gender (male and female) iii) Parental food (low and high) and the iv) interaction between parent and offspring on emergence time

<p><b>Copyright information:</b></p><p>Taken from "The effect of parental rearing conditions on offspring life history in "</p><p>http://www.malariajournal.com/content/6/1/130</p><p>Malaria Journal 2007;6():130-130.</p><p>Published online 24 Sep 2007</p><p>PMCID:PMC2034587.</p><p></p> Emergence time was measured as the number of days taken post hatching to emerge as an adult. In total the emergence time of 938 mosquitoes was recorded. For this and all following analysis, 'experimental block' interactions were fitted. Each graph including those below, represents the least square means and the associated standard error. Note that in some cases the dashed line is obscured by the solid line in the interaction graphs. 2b: Summary graphs showing the main effect of i) Offspring food ii) Gender iii) Parental food and the iv) interaction between parent and offspring on adult size. Adult size was determined from the wing length of each mosquito. In total the wing length of 747 mosquitoes was recorded. 2c: Summary graphs showing the main effect of i) Offspring food ii) Gender iii) Parental food, and the iv) interaction between parent and offspring on adult survival. Adult survival was determined as the number of days the mosquito remained alive, post hatching in the absence of water or glucose. In total the wing length of 747 mosquitoes was recorded