Shifting Patterns of Nitrogen Excretion and Amino Acid Catabolism Capacity during the Life Cycle of the Sea Lamprey (\u3cem\u3ePetromyzon mariunus\u3c/em\u3e)

The jawless fish, the sea lamprey (Petromyzon marinus), spends part of its life as a burrow-dwelling, suspension-feeding larva (ammocoete) before undergoing a metamorphosis into a free swimming, parasitic juvenile that feeds on the blood of fishes. We predicted that animals in this juvenile, parasitic stage have a great capacity for catabolizing amino acids when large quantities of protein-rich blood are ingested. The sixfold to 20-fold greater ammonia excretion rates (JAmm) in postmetamorphic (nonfeeding) and parasitic lampreys compared with ammocoetes suggested that basal rates of amino acid catabolism increased following metamorphosis. This was likely due to a greater basal amino acid catabolizing capacity in which there was a sixfold higher hepatic glutamate dehydrogenase (GDH) activity in parasitic lampreys compared with ammocoetes. Immunoblotting also revealed that GDH quantity was 10-fold and threefold greater in parasitic lampreys than in ammocoetes and upstream migrant lampreys, respectively. Higher hepatic alanine and aspartate aminotransferase activities in the parasitic lampreys also suggested an enhanced amino acid catabolizing capacity in this life stage. In contrast to parasitic lampreys, the twofold larger free amino acid pool in the muscle of upstream migrant lampreys confirmed that this period of natural starvation is accompanied by a prominent proteolysis. Carbamoyl phosphate synthetase III was detected at low levels in the liver of parasitic and upstream migrant lampreys, but there was no evidence of extrahepatic (muscle, intestine) urea production via the ornithine urea cycle. However, detection of arginase activity and high concentrations of arginine in the liver at all life stages examined infers that arginine hydrolysis is an important source of urea. We conclude that metamorphosis is accompanied by a metabolic reorganization that increases the capacity of parasitic sea lampreys to catabolize intermittently large amino acid loads arising from the ingestion of protein rich blood from their prey/hosts. The subsequent generation of energy-rich carbon skeletons can then be oxidized or retained for glycogen and fatty acid synthesis, which are essential fuels for the upstream migratory and spawning phases of the sea lamprey’s life cycle

Demography of sea lamprey (Petromyzon marinus) ammocoete populations in relation to potential spawning-migration obstructions

Copyright © 2017 John Wiley & Sons, Ltd. Recent advances in the understanding of lamprey migrations have led to concerns over the impacts of obstructions on the demography of many species. This study investigated sea lamprey (Petromyzon marinus) larvae (ammocoetes) in two adjacent but contrasting rivers, both designated Special Areas of Conservation under the EC Habitats Directive (92/43/EEC), one (the River Wye) with a small number of potential migration obstructions in its upper reaches and one (the River Usk) with obstacles along its course. The geographical distributions, densities and age structures of the ammocoete populations were examined in relation to the locations of potential obstructions to the spawning migrations of anadromous adults. A minimum of three age classes was recorded as far as 200 km upstream of the mouth of the River Wye (93% of the length of the mainstem), demonstrating that adults regularly migrate to the upper reaches of the catchment (downstream of a natural waterfall). By contrast, sea lamprey ammocoetes appeared to be absent (in suitable habitat) from 20 km (17%) of the River Usk, and there was a reduction in density, prevalence and the number of age classes upstream of two putative spawning-migration obstructions. This study highlights some of the potential impacts of habitat fragmentation by obstructions on the spawning migrations of anadromous species, as inferred from ammocoete demography. When used in combination to compare contiguous reaches, ammocoete densities, prevalence and age structure may be a useful indicator of which structures are likely to be important migration obstructions, and where further studies or mitigation efforts should be focused. It is likely that passage past some obstructions is enhanced if high river levels occur during the spawning migration, but there is a need to facilitate passage during all conditions, to improve access to under-exploited spawning and nursery areas

Quantifying Pacific lamprey (Entosphenous tridentatus) ammocoete habitat availability and the risk associated with the summer hydrograph recession limb in coastal northern California

Pacific lamprey (Entosphenus tridentatus) are an anadromous fish that evolved before dinosaurs and are critical to the Pacific coastal stream ecosystems and Native American cultures. Pacific lamprey are threatened by past natural resource exploitation (logging, mining, dams, and streamflow diversion) and climate change (warming temperature and changing precipitation regime). The lamprey larva, known as ammocoetes, live in fine sediment deposits in coastal streams for three to seven years. The objective of this research was to predict ammocoete habitat based on channel morphology in coastal Northern California, USA and explore the impact of streamflow diversions on their habitat. I surveyed stream reaches for geomorphological features including; bed elevation longitudinal profile, river terraces, grain size distribution, and occurrence of ammocoete habitat throughout the Klamath and North Coast regions. I developed a binomial prediction model for the prevalence of ammocoete habitat and a habitat density model in reaches where ammocoete habitat was measured. I also measured streamflow in Redwood Creek, a tributary to the South Fork Eel River near Redway, CA; constructed a three-dimensional model of ammocoete habitat deposits; and modeled impaired, with water diversions and landscape alterations, and unimpaired scenarios for the 1989-2019 dry seasons. Slope was the strongest predictor for the presence of ammocoete habitat, but was not useful for spatial modeling. Ammocoete habitat was often associated with the downstream end of an instream obstruction. Models of streamflow and ammocoete habitat indicated that an unimpaired stream might not have much risk to ammocoete habitat quality, but an impaired stream with surface water diversions can have extreme risk by dewatering ammocoete habitat annually. These results can help guide stream restoration by knowing where to focus restoration efforts, diversion management plans, and streamflow enhancement projects in coastal Northern California

Gill Structure & Function in Parasitic and Non-parasitic Lampreys: The Effects of Metamorphosis and Freshwater-Seawater Transfer

Lamprey (Petromyzontiformes) are a phylogenetically ancient group of jawless fishes that begin their lives as filter-feeding larvae (ammocoetes) before undergoing a complex metamorphosis into juvenile lamprey that involves major changes to their internal and external body plan. Some parasitic species, such as the sea lamprey (Petromyzon marinus), migrate to sea following metamorphosis, where they use their oral discs and rasping tongue to attach to and ingest vast quantities of blood from fishes. Thus, sea lamprey have to counter the simultaneous challenges of hyposmoregulation in sea water and the generation of large quantities of ammonia due to the catabolism of protein-rich blood. A goal of this study was to characterize how changes in the structure and function of the gills facilitated osmoregulation and nitrogenous waste (N-waste) excretion by sea lamprey following metamorphosis, particularly after acclimation to sea water and the ingestion of blood from teleost fishes. Accordingly, key features of the lamprey gill including the distribution and abundance of Na+/K+-ATPase (NKA) and H+-ATPase (V-ATPase) pumps involved in ion regulation, and ammonia transporting Rhesus glycoproteins and urea transporting proteins, were investigated using through immunohistochemical staining and Western blotting techniques. In contrast to the sea lamprey, there are other species of lamprey that remain in fresh water following metamorphosis. Many of these species are non-parasitic including the northern brook lamprey (Ichthyomyzon fossor), but some such as the closely related silver lamprey (Ichthymyzon unicuspis) are parasitic. To learn more about how an exclusively FW existence affected ion transport and ammonia excretion by lampreys, the gills of post-metamorphic (juvenile) northern and silver lamprey were compared to those of larval and juvenile sea lamprey. As in sea lamprey, the gills of both species were characterized by the presence of Rhesus c-like glycoprotein (Rhcg-like) and urea transport (UT) protein but, the distribution of these proteins more closely resembled those of larval sea lamprey than juvenile sea lamprey. In both the silver and northern brook lamprey, Rhcg-like protein co-localized with V-ATPase, suggesting that H+ excretion was coupled with Rhcg-like protein mediated diffusion trapping of NH3. Similarly, UT abundance in both species was comparable to that of the larval sea lamprey. I conclude that in freshwater lampreys, NH3 extrusion via apical Rhcg-like proteins is coupled to V-ATPase mediated H+ excretion, which maintains favourable diffusion gradients by trapping NH3 as NH4+. Given that the lampreys and teleosts have evolved along separate lineages for at least 360 million years, I propose that this method of ammonia excretion is an ancient strategy used by aquatic organisms to facilitate ammonia excretion across the gills in fresh water. In contrast, the need for V-ATPase trapping of NH3 as NH4+ is not required in sea water, in which the Rhcg-like proteins were restricted to the basolateral membrane and co-localized with NKA in sea water mitochondrion-rich cells (SW MRCs). These findings suggest that Rhcg-like protein may mediate ammonia excretion by loading the SW MRC with ammonia, with the resulting NH4+ pumped out of the cell via substitution for H+ on an apical Na+/H+ exchanger, or via an outwardly directed NH4+ electrochemical gradient that favours excretion via paracellular junctions

Mechanisms of Nitrogenous Waste Excretion During the Complex Life Cycle of the Sea Lamprey (Petromyzon marinus)

Sea lampreys (Petromyzon marinus) are a phylogenetically ancient jawless fish, with a multi-staged life cycle characterized by a prolonged suspension-feeding larval stage, which is followed by metamorphosis into parasitic lampreys that feed on the protein-rich blood of fishes. The switch from a nutrient poor to protein-rich diet in the sea lamprey is associated with an increased capacity to deaminate excess amino acids and to excrete ammonia and urea following metamorphosis. The focus of this thesis was to determine if changes in nitrogenous waste transporter protein abundance facilitate ammonia and urea excretion during different stages of the sea lamprey life cycle. To investigate the mechanisms by which nitrogenous waste excretion (JN-waste) occurs in sea lampreys, individuals of various lifestages (larval/adults) were exposed to environmental stressors (highly alkaline water and high external ammonia) that have been previously shown to affect JN-waste in other fishes. Both ammocoete and adult sea lamprey were unable to tolerate highly alkaline (HA: pH= 9.5) water for more than 24 h. However, exposure of ammocoetes and adult lamprey to high external ammonia (HEA; 0.5 mmol*L-1 ammonia) resulted in the reversal of ammonia excretion (JAmm) and a net uptake of ammonia over 2 days. In adults, urea excretion (JUrea) increased significantly but remained unchanged in ammocoetes. To determine whether there was a correlation between JN-waste patterns and the transport proteins associated with ammonia and urea excretion in sea lamprey, western blot analysis of Rh glycoproteins (Rhcg2) and urea transporters (UT) was performed on the main lifestages of sea lampreys (ammocoete, unfed parasitic, fed parasitic, adults) within gill and skin tissues. The abundances of Rhcg2 in the gill were significantly higher in fed parasites when compared to unfed juveniles and adult lamprey. Corresponding JAmm and plasma ammonia concentrations in these individuals were also greater. Larval sea lamprey UT protein abundances were significantly greater in gill tissues than in fed parasites and adult animals. This was postulated to be a function of the burrowing nature of the larval sea lampreys, and their relatively high rates of urea excretion compared to other life stages. The period of metamorphosis was also accompanied by marked changes in body condition factor (CF), along with JAmm and JUrea, which were initially depressed during the mid-stages of metamorphosis before increasing several-fold near the completion of metamorphosis. Both Rhcg2 and UT expression in the gills peaked at stage 4 of metamorphosis and declined to young adulthood, whereas Rhcg2 and UT expression in the skin of metamorphosing animals was below detectable levels. It is concluded that the changes in diet, along with habitat and activity level lead to the observed changes in the nitrogenous waste excretion patterns of the sea lamprey, which is reflected by corresponding changes in the abundance of the Rh and UT proteins. Further research into the regulation and localization of these proteins will prove useful in completing the picture of N-waste excretion in these phylogenetically ancient vertebrates

Distribution and habitat of unionid mussels and invasive sea lamprey larvae in the Paw Paw River, a tributary of Lake Michigan

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91129/1/j.1365-2427.2012.02777.x.pd

Morphogenesis of otoliths during larval development in brook lamprey, Lampetra planeri

Otolith morphogenesis of the brook lamprey, Lampetra planeri, was analysed from larval to adult stages. The brook lamprey remains juvenile for about 4 years, facilitating analysis of otoliths maturation that permits to identify relevant evolutionary traits in this primitive species and to compare our results with more evoluted species of vertebrate taxa. We combined histochemical, immunohistochemical, scanning electron microscopy, elemental analysis and X-ray diffraction of lamprey otoliths to establish possible relationships between otolithic mass, individual crystals, the otolithic organic substance that binds individual otoconia together and the inorganic elements that mineralize the lamprey otoliths. Histochemical analysis of the otoliths suggests that mineralization occurs gradually, beginning near the apex of the secretory epithelium. Then, the otoconia increase in size by deposition of layers of a dense crystalline substance. Immunohistochemical reactivity of calcium binding proteins indicates that calmodulin, calbindin, S-100 and parvalbumin are parts of the uncalcified organic mass that holds otoconia together. Imaging of the immunoreactivity of each protein by Confocal Laser Scanning Microscopy in ammocoete at the first year of the larval stage shows weak reaction products which, however, gradually increase in intensity, with peak value in ammocoete at the fourth year of the larval stage

Habitat selection and predation risk in larval lampreys

This thesis examines habitat preference and the influence of habitat on predation of larvae (ammocoetes) of the least brook lamprey (Lampetra aepyptera). The thesis comprises three chapters: (1) an introduction and literature review on the general life history of lampreys and on studies related to ammocoetes and their habitat, (2) an experimental study of habitat preference in ammocoetes of the least brook lamprey, and (3) an experimental study of the relationship between habitat availability and predation risk in ammocoetes. For the first study, we quantified substrate selection in small (\u3c 50 mm) and large (100-150 mm) ammocoetes of the least brook lamprey. In aquaria, ammocoetes were given a choice to burrow into six equally-available substrate types: small gravel (2.36-4.75 mm), coarse sand (0.5-1.4 mm), fine sand (0.125-0.5 mm), organic debris (approximately 70% decomposing leaves and stems, 15% silt, and 15% sand), an even mixture of silt, clay, and fine sand, and silt/clay (\u3c 0.063 mm). Fine sand was selected with a significantly higher probability than any other substrate. In the second study, we experimentally examined the influence of habitat availability on predation risk of ammocoetes. Ammocoetes were placed in aquaria containing a predator species (yellow bullhead, Ameiurus natalis) and one of 3 substrates: fine sand (0.125-0.5 mm), coarse sand (0.5-1.4 mm), or silt/clay (\u3c0.063 mm). Use of the three substrate types was based on a previous experiment where fine sand was determined to be the preferred benthic habitat of least brook lamprey. Based on 10 trials with each habitat type, survival of ammocoetes was highest in aquaria with fine sand (mean = 80%), and lower in those with coarse sand (mean = 58%) and silt/clay (mean = 4%). The results of both studies conducted indicate that populations of least brook lamprey ammocoetes may be limited by the availability of fine sand habitat. The first study indicated that least brook lamprey ammocoetes are habitat specialists, preferring substrates composed primarily of fine sand. The second study showed that the availability of fine sand habitat may influence the predation risk of ammocoetes, as ammocoete survival from predation was highest in fine sand, and lower in other substrates

Investigating New Methods to Improve Ageing and Study Movement Patterns of Larval Great Lakes Sea Lamprey (Petromyzon Marinus) Populations

Sea lampreys (Petromyzon marinus) are parasitic pests in the Great Lakes which have negatively impacted game fish populations. Management efforts to control sea lamprey populations throughout the Great Lakes began in the 1950s and continue today. The primary control technique used is the application of lampricides to streams to kill larvae before they become parasites. A better understanding of larval sea lamprey growth rates, age determination, and habitat preference is greatly needed to improve both selection of streams for lampricide application and to inform models of sea lamprey population dynamics. Otoliths have been used to estimate age in teleost fish through annuli counts and otolith size metrics. Lampreys do not have otoliths, having instead an analogous structure called a statolith. Determining age based on statolith annuli counts has been found to be imprecise and inaccurate. Therefore, I evaluated whether statolith size is correlated with sea lamprey larva, also known as ammocoete, age using known-age populations of ammocoetes from two contrasting Great Lakes streams. Statolith width was found to be the measurement that better distinguished the age-classes within the populations. When combining length-frequency and statolith width data into a likelihood-based statistical model I was able to more accurately assess ammocoete population age composition for one known-age population than when using only length-frequency data. Studies of the biology and ecology of Great Lakes sea lampreys (Petromyzon marinus) may require an effective means of tagging larvae to track individual movements to better control this pest species. I evaluated the feasibility of using passive integrated transponder (PIT) and visible implant (VI) Alpha tags in larval sea lampreys at least 100 mm and 85 mm in length, respectively. The use of PIT tags in lampreys as small as 100 mm in length is not suggested unless a tag burden of less than 5% can be achieved. Until a better method of wound closure is found to limit VI Alpha tag loss in lampreys, the use of these tags is not suggested in lampreys as small as those used in this study. If habitat preference, depth distribution, or in-stream distribution changes as larvae approach metamorphosis, as anecdotal evidence suggests, there is a potential for bias in the current ranking surveys which make the assumption that larval lampreys occupy habitat in the same proportion irrespective of size. To monitor the movement and preferred habitats of large larvae, I marked and released larvae approaching metamorphic size and subsequently tracked their movements. I used three different tagging methods, including passive integrated transponders (PIT) tags, visible implant (VI) Alpha tags, and visible implant elastomer (VIE) tags to mark larvae. Using PIT telemetry and electrofishing, I was able to locate 11% of our released ammocoetes. It was found that the larger ammocoetes moved further distances downstream from release locations than the smaller ammocoetes.Master of ScienceBiologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/112026/1/Potts2012_InvestigatingMethodsImproveAgeing.pd