Waterborne amino acids: uptake and functional roles in aquatic animals.

Dissolved organic matter is a ubiquitous component of freshwater and marine environments, and includes small nutrient molecules, such as amino acids, which may be available for uptake by aquatic biota. Epithelial transporters, including cotransporters, uniporters and antiporters, facilitate the absorption of dissolved amino acids (often against concentration gradients). Although there is a lack of mechanistic and molecular characterization of such transporters, pathways for the direct uptake of amino acids from the water appear to exist in a wide range of marine phyla, including Porifera, Cnidaria, Platyhelminthes, Brachiopoda, Mollusca, Nemertea, Annelida, Echinodermata, Arthropoda and Chordata. In these animals, absorbed amino acids have several putative roles, including osmoregulation, hypoxia tolerance, shell formation and metabolism. Therefore, amino acids dissolved in the water may play an important, but overlooked, role in aquatic animal nutrition.

Invasive investigation: uptake and transport of l-leucine in the gill epithelium of crustaceans.

Many aquatic species are well known as extremely successful invaders. The green crab (Carcinus maenas) is an arthropod native to European waters; however, it is now known to be a globally invasive species. Recently, it was discovered that the C. maenas could transport nutrients in the form of amino acids across their gill from the surrounding environment, a feat previously thought to be impossible in arthropods. We compared the ability for branchial amino acid transport of crustacean's native to Canadian Pacific waters to that of the invasive C. maenas, determining if this was a novel pathway in an extremely successful invasive species, or a shared trait among crustaceans. Active transport of l-leucine was exhibited in C. maenas, Metacarcinus gracilis, Metacarcinus magister, and Cancer productus across their gill epithelia. Carcinus maenas exhibited the highest maximum rate of branchial l-leucine transport at 53.7 ± 6.24 nmolg-1 h-1, over twice the rate of two native Canadian crustaceans. We also examined the influence of feeding, gill specificity, and organ accumulation of l-leucine. Feeding events displayed a heavy influence on the branchial transport rate of amino acids, increasing l-leucine transport rates by up to 10-fold in C. maenas. l-leucine displayed a significantly higher accumulation rate in the gills of C. maenas compared to the rest of the body at 4.15 ± 0.78 nmolg-1 h-1, with the stomach, hepatopancreas, eyestalks, muscle tissue, carapace and heart muscle exhibiting accumulation under 0.15 nmolg-1 h-1. For the first time, the novel transport of amino acids in Canadian native arthropods is described, suggesting that branchial amino acid transport is a shared trait among arthropods, contrary to existing literature. Further investigation is required to determine the influence of environmental temperature and salinity on transport in each species to outline any competitive advantages of the invasive C. maenas in a fluctuating estuarine environment.

Copper exposure does not alter the ability of intertidal sea cucumber Cucumaria miniata to tolerate emersion during low tide.

Intertidal animals experience cycles of tidal emersion from water and are vulnerable to copper (Cu) exposure due to anthropogenic toxicant input into marine waters. Both emersion and Cu toxicity can cause damage to physiological processes like aerobic metabolism, ammonia excretion, and osmoregulation, but the interactions of the combination of these two stressors on marine invertebrates are understudied. Mixed effects of 96 h of low and high Cu exposure (20 and 200 µg/L) followed by 6 h of tidal emersion were evaluated on the intertidal sea cucumber Cucumaria miniata. The respiratory tree accumulated the highest concentrations of Cu, followed by the introvert retractor muscle, body wall, and coelomic fluid. Emersion affected accumulation of Cu, perhaps by inhibiting excretion. 200 µg/L of Cu increased lactate production in the respiratory tree, indicative of damaged aerobic metabolism. Cu diminished ammonia excretion, but emersion increased oxygen uptake and ammonia excretion upon re-immersion. The combination of the two stressors did not have any interactive effects on metabolism or ammonia excretion. Neither Cu exposure nor emersion altered ion (sodium, potassium, calcium, magnesium) content of the coelomic fluid. Overall, results of this study suggest that Cu exposure does not alter C. miniata's high tolerance to emersion, and some potential strategies that this species uses to overcome environmental stress are illuminated.

Isolation of Bluetongue virus from canine abortions.

Three aborted canine fetuses were submitted to the Animal Health Diagnostic Center at Cornell University in November 2011 and September 2012 for diagnostic workups to determine the causes of the reproductive difficulties. Histological assessments of the sampled tissues were inconclusive due to the autolysis. Tests to detect bacterial causes of the abortions were also negative. Virus isolation testing on pooled tissues from the fetuses identified a cytopathogenic agent in cell cultures. Fluorescent antibody tests on the infected cells gave a positive reaction for Bluetongue virus, and subsequent serotype specific reverse transcription polymerase chain reaction assays identified the isolates as Bluetongue virus serotype 11. The current report describes the isolation of Bluetongue virus from dogs unrelated to contaminated vaccines and in the absence of a raw meat diet.