Do birds of a feather flock together? Comparing habitat preferences of piscivorous waterbirds in a lowland river catchment

Waterbirds can move into and exploit new areas of suitable habitat outside of their native range. One such example is the little egret (Egretta garzetta), a piscivorous bird which has colonised southern Britain within the last 30 years. Yet, habitat use by little egrets within Britain, and how such patterns of habitat exploitation compare with native piscivores, remains unknown. We examine overlap in habitat preferences within a river catchment between the little egret and two native species, the grey heron (Ardea cinerea) and great cormorant (Phalacrocorax carbo). All species showed strong preferences for river habitat in all seasons, with other habitat types used as auxiliary feeding areas. Seasonal use of multiple habitat types is consistent with egret habitat use within its native range. We found strong egret preference for aquatic habitats, in particular freshwaters, compared with pasture and arable agricultural habitat. Egrets showed greater shared habitat preferences with herons, the native species to which egrets are most morphologically and functionally similar. This is the first study to quantify little egret habitat preferences outside of its native range

Antigenic Importance of the Carboxy-Terminal Beta-Strand of the Porcine Reproductive and Respiratory Syndrome Virus Nucleocapsid Protein

Five domains of antigenic importance were previously mapped on the nucleocapsid protein (N) of the porcine reproductive and respiratory syndrome virus (PRRSV), and a domain comprised of the 11 C-terminal-most amino acids (residues 112 to 123) was shown to be essential for binding of N-specific conformation-dependent monoclonal antibodies (MAbs). In the present study, the importance of individual residues within this C-terminal domain for antigenicity was investigated using eight different mutant constructs of N expressed in HeLa cells. Single amino acid substitutions were introduced into the C-terminal domain of the N protein, and the significance of individual amino acids for MAb reactivity was determined by immunoprecipitation. None of the MAbs tested recognized the mutant with a leucine-to-proline substitution at residue 114 (L114P), while V112P, R113P, R113D, I115P, and R116P reduced MAb binding significantly. Conversely, substitution of amino acids at positions 118 (T118S) and 121 (P121A) had little effect on MAb binding. Secondary-structure predictions indicate that amino acids 111 to 117 form a beta-strand. In view of the fact that replacement of beta-strand-forming amino acids with proline elicited the greatest effect on MAb binding, it appears that secondary structure in the C terminus of the N protein is an important determinant of conformational epitope formation. While the crystal structure of the PRRSV N protein remains to be determined, results from these studies broaden our understanding of the secondary structures that make up the PRRSV N protein and shed some light on how they may relate to function