Modelling intraspecific resting egg shape variation in a freshwater fairy shrimp Tanymastix stagnalis (L., 1758) (Crustacea, Branchiopoda)

The shape of the resting eggs of a large branchiopod crustacean, the Anostraca Tanymastix stagnalis , is represented very accurately by analytical expressions. The occurrence of atypical shape of some T. stagnalis eggs may be viewed as a simple change of the analytical expression describing the usual egg shape. Their unusual shape may be explained by a higher embryo volume within an envelope of a given size. Biological implications are briefly discussed and hypothesized in an evolutionary point of view.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 55–60.     

Adult movements between populations in the specialist butterfly Proclossiana eunomia (Lepidoptera, Nymphalidae)

Abstract.

• 1 The structure of local populations of a monophagous butterfly, the bog fritillary Proclossiana eunomia, was studied in a complex of suitable habitat patches separated by spruce plantations or fertilized pasture.
• 2 An unexpected high level of adult movements between habitat patches was detected by a mark—release—recapture technique. Local populations were connected by adult movements across unsuitable habitats, leading to a meta-population structure.
• 3 This evidence of the metapopulation structure of a specialist butterfly challenges the supposed relationship between habitat specialization and closed, isolated populations.
• 4 Males and females of P.eunomia exhibited different spatial behaviours; females were more likely to emigrate and dispersed further than males. These differences in spatial behaviour are related to the mating system.

     

Isolation and characterization of tetranucleotide microsatellite markers in a mouth‐brooding haplochromine cichlid fish (Pseudocrenilabrus multicolor victoriae) from Uganda

Eight tetranucleotide microsatellite loci were isolated from the haplochromine cichlid fish, Pseudocrenilabrus multicolor victoriae, an important model species for studies in respiratory ecology, conservation, and evolution. We surveyed variation at these loci in 23 individuals from western Uganda, finding four to 19 alleles per locus and an average expected heterozygosity of 0.8575. These microsatellite loci will be used to examine gene flow and population structure in Ugandan P. m. victoriae.     

Crystal structures of mutant ribosomal proteins L1

Nine mutant ribosomal proteins L1 from the bacterium Thermus thermophilus and archaeon Methanococcus jannaschii were obtained and their crystal structures were determined and analyzed. The structure of the S179C TthL1 mutant, determined earlier, was also analyzed. In half of the proteins studied, point mutations of the amino acid residues exposed on the protein surface essentially changed the spatial structure of the protein. This proves that a correct study of biological processes with the help of site-directed mutagenesis requires a preliminary determination or, at least, modeling of the structures of mutant proteins. A detailed comparison of the structures of the L1 mutants and the corresponding wild-type L1 proteins demonstrated that the side chain of a mutated amino acid residue tends to adopt a location similar to that of the side chain of the corresponding residue in the wild-type protein. This observation assists in modeling the structure of mutant proteins.     

Crystal structures of mutant ribosomal proteins L1

Nine mutant forms of ribosomal proteins L1 from the bacterium Thermus thermophilus and the archaeon Methanococcus jannaschii were obtained. Their crystal structures were determined and analyzed. Earlier determined structure of S179C TthL1 was also thoroughly analyzed. Five from ten mutant proteins reveal essential changes of spatial structure caused by surface point mutation. It proves that for correct studies of biological processes by site-directed mutagenesis it is necessary to determine or at least to model spatial structures of mutant proteins. Detailed comparison of mutant L1 structures with that of corresponding wild type proteins reveals that side chain of a mutated amino acid residue tries to locate like the side chain of the original residue in the wild type protein. This observation helps to model the mutant structures.     

Ebola and Marburg viruses: the humans strike back

Ebola and Marburg viruses are the causative agents of rapidly progressive hemorrhagic fevers with high mortality rates. Pre- or post-exposure treatments against the diseases are currently not available for human use. In the field, establishment of strict quarantine measures preventing further virus transmission are still the only way to fight the infections. However, our knowledge of Ebola and Marburg viruses has markedly increased as a result of two recent discoveries discussed in this review. Chandran et al. have elucidated the mechanism by which Ebola GP is converted to a fusion-active form. Infectivity of Ebola virus was shown to be dependent on the cleavage of GP by cellular endosomal proteases, cathepsin B and L, thus opening new therapeutic approaches options. As for Jones SM et al., they have successfully vaccinated monkeys with recombinant vesicular stomatitis virus expressing Ebola or Marburg virus surface glycoprotein GP, a promising vaccine approach.     

New insights into the interaction of ribosomal protein L1 with RNA

The RNA-binding ability of ribosomal protein L1 is of profound interest, since L1 has a dual function as a ribosomal structural protein that binds rRNA and as a translational repressor that binds its own mRNA. Here, we report the crystal structure at 2.6 A resolution of ribosomal protein L1 from the bacterium Thermus thermophilus in complex with a 38 nt fragment of L1 mRNA from Methanoccocus vannielii. The conformation of RNA-bound T.thermophilus L1 differs dramatically from that of the isolated protein. Analysis of four copies of the L1-mRNA complex in the crystal has shown that domain II of the protein does not contribute to mRNA-specific binding. A detailed comparison of the protein-RNA interactions in the L1-mRNA and L1-rRNA complexes identified amino acid residues of L1 crucial for recognition of its specific targets on the both RNAs. Incorporation of the structure of bacterial L1 into a model of the Escherichia coli ribosome revealed two additional contact regions for L1 on the 23S rRNA that were not identified in previous ribosome models.