Evaluation of a real-time polymerase chain reaction assay of the outer membrane protein P2 gene for the detection of Haemophilus parasuis in clinical samples

A real-time polymerase chain reaction (PCR) assay of the outer membrane protein (OMP) P2 gene was developed and used to test 97 putative Haemophilus parasuis pure cultures and 175 clinical tissue samples. With standard culture isolation as the gold standard, the diagnostic sensitivity and specificity of the PCR assay were determined to be 83% and 80%, respectively.     

Prion protein genotypes of sheep as determined from 3343 samples submitted from Ontario and other provinces of Canada from 2005 to 2012

This study analyzed sheep prion protein (PrP) genotypes of samples submitted from Ontario and other provinces of Canada to the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, between 2005 and 2012. In Ontario, the proportion of scrapie-resistant sheep increased from 2005 to 2012 as evidenced by an increase in the ARR haplotype. When Canadian provinces (Alberta, Ontario, Quebec, and Nova Scotia) were compared from 2008 to 2012, a high proportion of scrapie-resistant sheep was found in all the provinces. The proportions of resistant sheep were lower in Alberta and Quebec than in Ontario and Nova Scotia. Alberta had higher proportions of susceptible sheep and a higher frequency of VRQ alleles, and Quebec had a higher frequency of the ARQ allele.     

Particular problems for the conservation of diadromous fish

1. Known diadromous fish number <250 species, and <1.5% of fish species. 2. They comprise ca. 3% of species regarded as ‘endangered’. 3. Amongst them are species of great importance to fisheries, and out of proportion to their number. 4. They occupy complexes of connected habitats between or through which passage is needed at two or more life history phases. 5. They therefore pose special problems for conservation which relate to: a. diversity of habitats; b. huge areas occupied; c. the spatial separation of the various habitats used; d. need for fish passage; e. often heavy exploitation. 6. These problems are often the opposite of those experienced with species that occupy local habitats and which are in danger of local extirpation.     

Anadromy and homing: two life‐history traits with adaptive synergies in salmonid fishes?

Anadromy and homing are two traits found widely amongst teleost fishes. They co-occur in salmonid fishes, and probably also in other fish families. Anadromy provides fish with the opportunity for more rapid growth, larger size, and higher fecundity through the exploitation of rich food resources and favourable growing temperatures in the sea, but may result in higher predation mortalities and has the tendency to disperse stocks very widely. Homing fosters adaptation of stocks to favourable local spawning conditions, but the dispersive effects of anadromy, in the absence of homing, may tend to break down such local adaptation. A low percentage of straying in species that home may have long-term evolutionary advantages. This paper explores the question of whether homing may be a preadaptation for successful evolution of anadromy, or whether the two attributes have coevolved.     

Evaluation of the zoonotic potential of Giardia duodenalis in fecal samples from dogs and cats in Ontario

This study determined the distribution and zoonotic potential of Giardia duodenalis assemblage types among canine and feline fecal samples from Ontario. The effectiveness of Giardia assemblage typing methods by sequencing the genes of small subunit ribosomal RNA (ssu-rRNA), β-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) was evaluated simultaneously. From 2008 to 2010, 118 canine and 15 feline Giardia positive fecal samples were tested. The ssu-rRNA sequencing method typed 64% (75/118) and 87% (13/15) of the Giardia-positive canine and feline samples, respectively. Among the typeable samples, 68% (51/75) of canine samples contained G. duodenalis assemblage D and 31% (23/75) contained G. duodenalis assemblage C (both non-zoonotic assemblage types). Only 1% (1/75) of the typeable canine samples contained a potentially zoonotic assemblage B. In contrast, 100% (13/13) of the typeable feline samples contained potentially zoonotic assemblages A (n = 12) or B (n = 1).     

Ancestry and amphidromy in island freshwater fish faunas

Amphidromy is a frequent attribute of fish faunas of remote islands, where the presence of freshwater fishes creates perplexity as to how such remote places came to have ‘freshwater fish’. Not infrequently, the fact that amphidromous species spend part of their lives in the sea is invoked as indicating that such species have marine ancestries, and this is the implied explanation for presence of freshwater fishes on islands. However, examination of the ranges of some amphidromous species, and of the distributions of genera to which amphidromous fishes belong, strongly suggests that amphidromy, especially in the gobies of the subfamily Sicydiinae, is a widespread, probably ancestral trait. Rather than such amphidromous fish having a marine ancestry, their marine life stages are themselves the likely key element in explaining their distributions.     

Aquatic productivity and the evolution of diadromous fish migration

Diadromous migration, in which some fish species migrate from freshwater and feed in the ocean (anadromous species) and others migrate from the ocean and feed in freshwater (catadromous), has long been perplexing. However, when the distribution of diadromous species is examined with respect to global patterns in aquatic productivity, this apparent paradox is resolved. The contrasting directions of migration can largely be explained by the relative availability of food resources in ocean and freshwater habitats. Oceans are more productive than freshwaters in temperate latitudes, and anadromous species predominate. In contrast, catadromous species generally occur in tropical latitudes where freshwater productivity exceeds that of the ocean.     

On amphidromy, a distinct form of diadromy in aquatic organisms

Amphidromy is a distinctive form of diadromy that involves some fish, decapod crustaceans and gastropod molluscs. Characteristic elements in amphidromy are: reproduction in fresh water, passage to sea by newly hatched larvae, a period of feeding and growing at sea usually a few months long, return to fresh water of well‐grown juveniles, a further period of feeding and growing in fresh water, followed by reproduction there. This life‐history strategy is observed in numerous fish species, primarily in islands of the tropics and subtropics (probably more than 75 species, especially sicydiine gobies), and extends to temperate countries as far as Japan in the north and New Zealand in the south. There has been considerable confusion about the nature of amphidromy and its distinctiveness from anadromy, another category of diadromy. The return to freshwater of small juveniles of amphidromous fishes is functionally and strategically different from the return of large mature adults, as happens in anadromy. The strategy is recognized as distinctive by numerous fish biologists who work with amphidromous fishes, although it has tended to be rejected or ignored by others, typically those who have no personal experience with them.     

The possible adaptive advantages of terrestrial egg deposition in some fluvial diadromous galaxiid fishes (Teleostei: Galaxiidae)

Several diadromous New Zealand and Australian species of Galaxias are now known, or suspected, to deposit their eggs amongst riparian vegetation or substrates either supratidally in estuaries or in forested streams in locations that are only temporarily submerged by elevated water levels. The eggs develop in a humid atmosphere and hatch when the egg deposition sites are resubmerged; a significant role for agitation in stimulating hatching seeming likely. There are risks from the eggs becoming dehydrated, and also from a failure by water to resubmerge the eggs before they have exhausted their energy resources. Hatching is triggered by elevated flows, perhaps being an outcome of agitation of the eggs. Elevated flows may also increase the rate of downstream transport of the larvae, facilitating survival during dispersal to sea from spawning sites in streams that may be long distances inland. Hatching during flood events may favour survival of the larvae because turbid flows may provide ‘cover’ for the larvae as they emigrate to sea. Risks from egg predation by aquatic predators may be replaced by risks from terrestrial predators.