Interaction between Mycobacterium avium subsp. paratuberculosis and environmental protozoa

BACKGROUND: Interactions between Mycobacterium avium subsp. paratuberculosis (Map) and free-living protozoa in water are likely to occur in nature. The potential impact of ingestion of Map by two naturally occurring Acanthamoeba spp. on this pathogen's survival and chlorine resistance was investigated. RESULTS: Between 4.6 and 9.1% of spiked populations of three Map strains (NCTC 8578, B2 and ATCC 19698), which had been added at a multiplicity of infection of 10:1, were ingested by Acanthamoeba castellanii CCAP 1501/1B and A. polyphaga CCAP 1501/3B during co-culture for 3 h at 25°C. Map cells were observed to be present within the vacuoles of the amoebae by acid-fast staining. During extended co-culture of Map NCTC 8578 at 25°C for 24 d with both A. castellanii and A. polyphaga Map numbers did not change significantly during the first 7 days of incubation, however a 1–1.5 log(10 )increase in Map numbers was observed between days 7 and 24 within both Acanthamoeba spp. Ingested Map cells were shown to be more resistant to chlorine inactivation than free Map. Exposure to 2 μg/ml chlorine for 30 min resulted in a log(10 )reduction of 0.94 in ingested Map but a log(10 )reduction of 1.73 in free Map (p < 0.001). CONCLUSION: This study demonstrated that ingestion of Map by and survival and multiplication of Map within Acanthamoeba spp. is possible, and that Map cells ingested by amoebae are more resistant to inactivation by chlorine than free Map cells. These findings have implications with respect to the efficacy of chlorination applied to Map infected surface waters

A4_9 Electric Ray Fish

This paper examines how a higher resistivity of freshwater, in comparison to saltwater, results in an increased emf output produced by strongly electric ray fish in this habitat. It is discussed how the arrangement of biological electric cells relates to the emf output for both freshwater and saltwater fish

A4_14 How to score a goal

This paper examines the force causing a football to curve when an angular velocity, or spin, is imparted. A relationship between the distance travelled by the football, in the direction it is kicked, and the amount that the path bends is found.Â

A4_7 Terraforming Mars – Orbital Mirrors: Construction

This report examines the feasibility of building orbital mirrors at Mars to increase the surface temperature by reflecting used solar energy. It was found that while a large solar mirror can be constructed with current technology the infrastructure to carry out the operation over Mars does not exist

A4_8 Terraforming Mars - Orbital Mirrors: Operation

This paper looks at the temperature changes to the Martian surface of using orbital mirrors to heat it. It was found that net changes to the whole system would not be useful while localised temperature gains are enough to sublimate Martian ice to release water vapour and greenhouse gases

A4_16 How Long will the Milky Way Last?

This article investigates how long the Milky Way can sustain the current star formation rate. It is assumed in this journal that no appreciable mass is added, and neglects star death. It is found in this paper that the Milky Way can continue with its current estimated star formation rate of 7.5 stars per year for another 9.1 x 109 years

A4_1 Space Travel using Relativity

This paper has compared two different ships that use time dilation phenomenon to travel across space in one crew’s lifetime. One ship travels close to the speed of light at constant velocity while the other travels under constant acceleration of 1g. It was found that the constant acceleration can travel 2,000,000 light-years in half the crew time it takes the other to travel 200 light-years. However only the constant velocity ship is feasible in its application due to fuel requirements