Directional genetic selection by pulp mill effluent on multiple natural populations of three-spined stickleback (Gasterosteus aculeatus)

Contamination can cause a rapid environmental change which may require populations to respond with evolutionary changes. To evaluate the effects of pulp mill effluents on population genetics, we sampled three-spined sticklebacks (Gasterosteus aculeatus) near four pulp mills and four adjacent reference sites and analyzed Amplified Fragment Length Polymorphism (AFLP) to compare genetic variability. A fine scale genetic structure was detected and samples from polluted sites separated from reference sites in multidimensional scaling plots (P < 0.005, 1000 permutations) and locus-by-locus Analysis of Molecular Variance (AMOVA) further confirmed that habitats are significantly separated (FST = 0.021, P < 0.01, 1023 permutations). The amount of genetic variation between populations did not differ between habitats, and populations from both habitats had similar levels of heterozygosity (polluted sites Nei’s Hs = 0.11, reference sites Nei’s Hs = 0.11). Still, pairwise FST: s between three, out of four, pairs of polluted-reference sites were significant. A FST-outlier analysis showed that 21 (8.4%) loci were statistically different from a neutral distribution at the P < 0.05 level and therefore indicated to be under divergent selection. When removing 13 FST-outlier loci, significant at the P < 0.01 level, differentiation between habitats disappeared in a multidimensional scaling plot. In conclusion, pulp mill effluence has acted as a selective agent on natural populations of G. aculeatus, causing a convergence in genotype composition change at multiple sites in an open environment

A Novel DBL-Domain of the P. falciparum 332 Molecule Possibly Involved in Erythrocyte Adhesion

Plasmodium falciparum malaria is brought about by the asexual stages of the parasite residing in human red blood cells (RBC). Contact between the erythrocyte surface and the merozoite is the first step for successful invasion and proliferation of the parasite. A number of different pathways utilised by the parasite to adhere and invade the host RBC have been characterized, but the complete biology of this process remains elusive. We here report the identification of an open reading frame (ORF) representing a hitherto unknown second exon of the Pf332 gene that encodes a cysteine-rich polypeptide with a high degree of similarity to the Duffy-binding-like (DBL) domain of the erythrocyte-binding-ligand (EBL) family. The sequence of this DBL-domain is conserved and expressed in all parasite clones/strains investigated. In addition, the expression level of Pf332 correlates with proliferation efficiency of the parasites in vitro. Antibodies raised against the DBL-domain are able to reduce the invasion efficiency of different parasite clones/strains. Analysis of the DBL-domain revealed its ability to bind to uninfected human RBC, and moreover demonstrated association with the iRBC surface. Thus, Pf332 is a molecule with a potential role to support merozoite invasion. Due to the high level of conservation in sequence, the novel DBL-domain of Pf332 is of possible importance for development of novel anti-malaria drugs and vaccines

Contribution to Wideband SAR Space-Time Processing, and Radar Remote Sensing of Sea Ice

Synthetic Aperture Radar (SAR) has the capability to map the Earth with high resolution and is used in both civilian and military applications. The development of SAR systems is going towards higher resolution. Today there are Wide Band (WB) SAR instruments that have a resolution actually smaller than the operating wavelength. One example is the CARABAS sensor developed by the Swedish Defence Research Establishment (FOA). It operates at VHF and has shown many unique capabilities such as the detection of concealed targets. Great efforts are being made to build WB SAR systems at higher frequencies. One of these projects is the LORA project at FOA. The LORA system will operate on UHF and it will have several antenna channels which can be used for space-time processing, e.g. to suppress clutter and jammers, and to detect ground moving targets. In this thesis we have considered two different areas connected with SAR. In the first part we develop space-time adaptive algorithms for WB SAR systems with array antennas. The aim of the work is to detect ground moving targets and to suppress strong clutter and jammer noise. A likelihood ratio test is proposed for detection. The method combines fast backprojection algorithms with target detection. Moving targets are focused using their proper relative speed. The methodology has been tested on narrow band data. Bistatic antenna effects on WB SAR systems for moving target indication are discussed. Simulations of WB SAR using combined fast backprojection and clutter suppression are presented. Jammer suppression is tested for WB SAR, using space-time adaptive processing. The results are from an experiment with the CARABAS radar. In the second part we examine what a microwave radar sensor actually senses in sea ice and we investigate the capability of the SAR onboard the ERS-1 satellite to classify Arctic sea ice. Polarimetric scatterometer measurements have been carried out at microwave frequencies (L-, S-, C- and X-band). The measurements are compared with scattering models. Conclusions are made of what the radar senses in sea ice, for the different ice types. Sea ice classification methods are tested on ERS-1 SAR images and compared with classifications made by the NASA team algorithm on data from the DMSP satellites Special Scanning Microwave Imager (SSM/I). The results are compared with in situ measurements

Contribution to Wideband SAR Space-Time Processing, and Radar Remote Sensing of Sea Ice

Synthetic Aperture Radar (SAR) has the capability to map the Earth with high resolution and is used in both civilian and military applications. The development of SAR systems is going towards higher resolution. Today there are Wide Band (WB) SAR instruments that have a resolution actually smaller than the operating wavelength. One example is the CARABAS sensor developed by the Swedish Defence Research Establishment (FOA). It operates at VHF and has shown many unique capabilities such as the detection of concealed targets. Great efforts are being made to build WB SAR systems at higher frequencies. One of these projects is the LORA project at FOA. The LORA system will operate on UHF and it will have several antenna channels which can be used for space-time processing, e.g. to suppress clutter and jammers, and to detect ground moving targets. In this thesis we have considered two different areas connected with SAR. In the first part we develop space-time adaptive algorithms for WB SAR systems with array antennas. The aim of the work is to detect ground moving targets and to suppress strong clutter and jammer noise. A likelihood ratio test is proposed for detection. The method combines fast backprojection algorithms with target detection. Moving targets are focused using their proper relative speed. The methodology has been tested on narrow band data. Bistatic antenna effects on WB SAR systems for moving target indication are discussed. Simulations of WB SAR using combined fast backprojection and clutter suppression are presented. Jammer suppression is tested for WB SAR, using space-time adaptive processing. The results are from an experiment with the CARABAS radar. In the second part we examine what a microwave radar sensor actually senses in sea ice and we investigate the capability of the SAR onboard the ERS-1 satellite to classify Arctic sea ice. Polarimetric scatterometer measurements have been carried out at microwave frequencies (L-, S-, C- and X-band). The measurements are compared with scattering models. Conclusions are made of what the radar senses in sea ice, for the different ice types. Sea ice classification methods are tested on ERS-1 SAR images and compared with classifications made by the NASA team algorithm on data from the DMSP satellites Special Scanning Microwave Imager (SSM/I). The results are compared with in situ measurements