Characterisation of intestinal amino acid and oleic acid absorption and their interaction in the Pacific spiny dogfish (Squalus suckleyi).

Elasmobranchs are commonly carnivores and are important in energy transfer across marine ecosystems. Despite this, relatively few studies have examined the physiological underpinnings of nutrient acquisition in these animals. Here, we investigated the mechanisms of uptake at the spiral valve intestine for two representative amino acids (-alanine, -leucine) and one representative fatty acid (oleic acid), each common to the diet of a carnivore, the Pacific spiny dogfish (Squalus suckleyi).

Effect of L-alanine exposure during early life stage on olfactory development, growth and survival in age-0 lake sturgeon .

Environmental factors play an important role in phenotypic development of fishes, which has implications for hatchery-reared fishes that are released into the wild where natural cues are present. There is interest in examining how early exposure to dietary odourants can affect development of olfaction. The aim of our study was to use behavioural, molecular and electro-physiological techniques to evaluate how introduction of the amino acid L-alanine to the rearing environment might influence the development of olfactory perception of dietary cues, growth and survival in lake sturgeon (), a species of conservation concern.

Absence of a functional gut microbiome impairs host amino acid metabolism in the Pacific spiny dogfish (Squalus suckleyi).

Nitrogen recycling and amino acid synthesis are two notable ways in which the gut microbiome can contribute to host metabolism, and these processes are especially important in nitrogen-limited animals. Marine elasmobranchs are nitrogen limited as they require substantial amounts of this element to support urea-based osmoregulation. However, following antibiotic-induced depletion of the gut microbiome, elasmobranchs are known to experience a significant decline in circulating urea and employ compensatory nitrogen conservation strategies such as reduced urea and ammonia excretion.

Integrated organismal responses induced by projected levels of CO and temperature exposures in the early life stages of lake sturgeon.

Atmospheric CO and temperature are rising concurrently, and may have profound impacts on the transcriptional, physiological and behavioural responses of aquatic organisms. Further, spring snowmelt may cause transient increases of pCO in many freshwater systems. We examined the behavioural, physiological and transcriptomic responses of an ancient fish, the lake sturgeon (Acipenser fulvescens) to projected levels of warming and pCO during its most vulnerable period of life, the first year.

The chondrichthyan glucagon-like peptide 3 regulates hepatic ketone metabolism in the Pacific spiny dogfish Squalus suckleyi.

Chondrichthyans have a novel proglucagon-derived peptide, glucagon-like peptide (GLP)-3, in addition to GLP-1 and GLP-2 that occur in other vertebrates. Given that the GLPs are important regulators of metabolic homeostasis across vertebrates, we sought to investigate whether GLP-3 displays functional actions on metabolism within a representative chondrichthyan, the Pacific spiny dogfish Squalus suckleyi. There were no observed effects of GLP-3 perfusion (10 nM for 15 min) on the rate of glucose or oleic acid acquisition at the level of the spiral valve nor were there any measured effects on intermediary metabolism within this tissue.

Understanding olfactory and behavioural responses to dietary cues in age-1 lake sturgeon Acipenser fulvescens.

Detection of environmental cues is essential for all vertebrates and is typically established by the olfactory epithelium and olfactory sensory neurons (OSNs). In fishes, microvillous and ciliated OSNs are the principal types, typically detecting amino acids and bile salts, respectively. Activation of OSN receptors by specific ligands initiate downstream signal processing often leading to behavioural responses.

Physiological responses to acute warming at the agitation temperature in a temperate shark.

Thermal tolerance and associated mechanisms are often tested via the critical thermal maximum (CTmax). The agitation temperature is a recently described thermal limit in fishes that has received little mechanistic evaluation. The present study used a temperate elasmobranch fish to test the hypothesis that this thermal tolerance trait is partially set by the onset of declining cardiorespiratory performance and the cellular stress response.

Comparison of metabolic rate between two genetically distinct populations of lake sturgeon.

Environmental temperatures differ across latitudes in the temperate zone, with relatively lower summer and fall temperatures in the north leading to a shorter growing season prior to winter. As an adaptive response, during early life stages, fish in northern latitudes may grow faster than their conspecifics in southern latitudes, which potentially manifests as different allometric relationships between body mass and metabolic rate. In the present study, we examined if population or year class had an effect on the variation of metabolic rate and metabolic scaling of age-0 lake sturgeon () by examining these traits in both a northern (Nelson River) and a southern (Winnipeg River) population.

In situ method for the determination of nutrient acquisition and its hormonal regulation in the spiral valve of two chondrichthyan fishes.

Chondrichthyans play an important role in nutrient cycling of many marine ecosystems, yet little is known about their nutritional physiology particularly relating to nutrient acquisition in the spiral valve intestine. This unique organ poses challenges for examining nutrient transport physiology using traditional reductionist methods owing to its scroll-like morphology. Thus, we established a method for the characterization of nutrient uptake rates in two representative chondrichthyans, the Pacific spiny dogfish () and the Pacific spotted ratfish ().

Tissue-specific transcriptomes reveal potential mechanisms of microbiome heterogeneity in an ancient fish.

The lake sturgeon (Acipenser fulvescens) is an ancient, octoploid fish faced with conservation challenges across its range in North America, but a lack of genomic resources has hindered molecular research in the species. To support such research, we created a transcriptomic database from 13 tissues: brain, esophagus, gill, head kidney, heart, white muscle, liver, glandular stomach, muscular stomach, anterior intestine, pyloric cecum, spiral valve and rectum. The transcriptomes for each tissue were sequenced and assembled individually from a mean of 98.

Using 15N to determine the metabolic fate of dietary nitrogen in North Pacific spiny dogfish (Squalus acanthias suckleyi).

Marine elasmobranchs are ureosmotic, retaining large concentrations of urea to balance their internal osmotic pressure with that of the external marine environment. The synthesis of urea requires the intake of exogenous nitrogen to maintain whole-body nitrogen balance and satisfy obligatory osmoregulatory and somatic processes. We hypothesized that dietary nitrogen may be directed toward the synthesis of specific nitrogenous molecules in post-fed animals; specifically, we predicted the preferential accumulation and retention of labelled nitrogen would be directed towards the synthesis of urea necessary for osmoregulatory purposes.

Investigating nitrogen movement in North Pacific spiny dogfish (Squalus acanthias suckleyi), with focus on UT, Rhp2, and Rhbg mRNA abundance.

For ureosmotic marine elasmobranchs, the acquisition and retention of nitrogen is critical for the synthesis of urea. To better understand whole-body nitrogen homeostasis, we investigated mechanisms of nitrogen trafficking in North Pacific spiny dogfish (Squalus acanthias suckleyi). We hypothesized that the presence of nitrogen within the spiral valve lumen would affect both the transport of nitrogen and the mRNA abundance of a urea transporter (UT) and two ammonia transport proteins (Rhp2, Rhbg) within the intestinal epithelium.

Elevated temperatures reduce population-specific transcriptional plasticity in developing lake sturgeon (Acipenser fulvescens).

Rising mean and variance in temperatures elevates threats to endangered freshwater species such as lake sturgeon, Acipenser fulvescens. Previous research demonstrated that higher temperatures during development result in physiological consequences for lake sturgeon populations throughout Manitoba, Canada, with alteration of metabolic rate, thermal tolerance, transcriptional responses, growth and mortality. We acclimated lake sturgeon (30-60 days post fertilization, a period of high mortality) from northern and southern populations (56°02'46.

Elevated temperatures dampen the innate immune capacity of developing lake sturgeon (Acipenser fulvescens).

Chronic exposure to high temperatures may leave freshwater fishes vulnerable to opportunistic pathogens, particularly during early life stages. Lake sturgeon, Acipenser fulvescens, populations within the northern expanse of their range in Manitoba, Canada, may be susceptible to high temperature stress and pathogenic infection. We acclimated developing lake sturgeon for 22 days to two ecologically relevant, summer temperatures (16 and 20°C).

Nitrogen transporters along the intestinal spiral valve of cloudy catshark (Scyliorhinus torazame): Rhp2, Rhbg, UT.

As part of their osmoregulatory strategy, marine elasmobranchs retain large quantities of urea to balance the osmotic pressure of the marine environment. The main source of nitrogen used to synthesize urea comes from the digestion and absorption of food across the gastrointestinal tract. In this study we investigated possible mechanisms of nitrogen movement across the spiral valve of the cloudy catshark (Scyliorhinus torazame) through the molecular identification of two Rhesus glycoprotein ammonia transporters (Rhp2 and Rhbg) and a urea transporter (UT).

Oil Infrastructure has Greater Impact than Noise on Stress and Habitat Selection in Three Grassland Songbirds.

Oil extraction may impact wildlife by altering habitat suitability and affecting stress levels and behavior of individuals, but it can be challenging to disentangle the impacts of infrastructure itself on wildlife from associated noise and human activity at well sites. We evaluated whether the demographic distribution and corticosterone levels of three grassland passerine species (Chestnut-collared Longspur, Calcarius ornatus; Baird's Sparrow, Centronyx bairdii; and Savannah Sparrow Passerculus sandwichensis) were impacted by oil development in southern Alberta, Canada. We used a landscape-scale oil well noise-playback experiment to evaluate whether impacts of wells were caused by noise.

Spatiotemporal variation of ringed seal blubber cortisol levels in the Canadian Arctic.

Climate change in the Arctic has widespread and complex effects on the health of animals and their populations. We used radioimmunoassay to measure blubber cortisol in ringed seals () sampled in Ulukhaktok, Inuvialuit Settlement Region, Northwest Territories, Canada (spring, 2002, 2004-2005, 2007-2012) and Arviat, Nunavut, Canada (autumn, 2003-2012) to examine chronic stress relative to biology (age, sex, length), body condition (blubber depth), and diet (δC, δN, and isotopic niche size). Ulukhaktok ringed seals had higher cortisol concentrations overall (0.

The gut microbiome may influence post-prandial nitrogen handling in an elasmobranch, the Pacific spiny dogfish (Squalus suckleyi).

Nitrogen recycling through the gut microbiome is an important mechanism used throughout vertebrates to reclaim valuable nitrogen trapped in urea. Evidence suggests it may be especially important in nitrogen limited animals, yet little is known about its role in marine elasmobranchs, which are said to be severely nitrogen limited. In the present study we used antibiotics to deplete the gut microbiome of Pacific spiny dogfish and assessed the role of the microbiome in nitrogen handling in both fed and fasted states.

Sustained endocrine and exocrine function in the pancreas of the Pacific spiny dogfish post-feeding.

Secretions of the exocrine pancreas contain digestive enzymes integral to the digestive process. The Pacific spiny dogfish (Squalus suckleyi) has a discrete pancreas, divided into two lobes termed the dorsal and ventral lobes. These lobes drain into the anterior intestine via a common duct to enable digestion.

Long-term effects of temperature during early life on growth and fatty acid metabolism in age-0 Lake Sturgeon (Acipenser fulvescens).

Environmental temperature during early life may have prolonged effects on growth and fatty acid metabolism, which could strongly influence overwintering survival in the first year of life for temperate-zone fish. In the present study, we examined how temperature during early life history might influence growth performance and fatty acid metabolism in age-0 Lake Sturgeon (Acipenser fulvescens) when exposed to cold temperatures at later stages. Fish were initially at 16 °C and subsequently held at 16 °C or 20 °C for 60 days beginning at 34 days post fertilization (dpf).

Effects of Dietary Shifts on Ontogenetic Development of Metabolic Rates in Age 0 Lake Sturgeon ().

AbstractIn many fish species, ontogenetic dietary shifts cause changes in both quantitative and qualitative intake of energy, and these transitions can act as significant bottlenecks in survival within a given year class. In the present study, we estimated routine metabolic rate (RMR) and forced maximum metabolic rate (FMR) in age 0 lake sturgeon () on a weekly basis from 6 to 76 days posthatch (dph) within the same cohort of fish. We were particularly interested in the period of dietary transition from yolk to exogenous feeding between 6 and 17 dph and as the fish transitioned from an artemia-based diet to a predominantly bloodworm diet between 49 and 67 dph.

EMS Experience Caring and Communicating with Patients and Families with a Life-Limiting-Illness.

The emergency medical services (EMS) system was designed to reduce death and disability and EMS training focuses on saving lives through resuscitation, aggressive treatment and transportation to the emergency department. EMS providers commonly care for patients who have life-limiting illnesses. The objective was to explore EMS provider challenges, self-perceived roles and training experiences caring for patients and families with life-limiting illness.