Specialerapporter og -abstracts

The effect of viscosin on aerosolization of pseudomonas fluorescens strain SBW25

Lund-Larsen, Johannes Felipe, 28.06.2018

In my master thesis I addresses the question of how aerosolization of bacteria and their survival is affected by the presence of biosurfactants.
Biosurfactants are produced by bacteria for different reasons. In the marine environments biosurfactants are for instance produced to disperse very hydrophobic compounds such as oil. As a result, bacterial cells can more easily attach to these hydrophobic compounds and can use the compounds as energy sources. In terrestrial environments one of the commonly found biosurfactants is viscosin that is produced by strains of the species Pseudomonas fluorescens including the strain Pseudomonas fluorescens SBW25. Viscosin has been found to be very effective against zoospores of the late blight disease Phytophthora infestans. It was found to solubilize the zoospores. It has also been found that viscosin wets waxy surfaces such as in broccoli florets by reducing surface tension. Thereby it makes it easier for P. fluorescens SBW25 to attach to the legume.
In this thesis I specifically tested how viscosin affected aerosolization of P. fluorescens SBW25 from a water body by simulating the bubble bursting process. This was done by injecting P. fluorescens SBW25 cultures with gene deletion for ViscA into a bubble tank, with and without addition of viscosin added to the water. A gas distribution tube was used to inject a constant air flow at the bottom of the tank, to generate bubbles. The number of particles that were ejected when bubbles burst at the waterair interphase and their size distribution were determined by an optical particle sizer (OPS). I examined how the viscosin affected the cells that were ejected by bubble bursting as a function of viscosin concentration of viscosin at the water surface and the bulk water after viscosin addition to the surface or to the bulk water.
Experiments with viscosin addition but without bacterial cells were carried out to study the partitioning of viscosin between the bulk water and the surface water.
In addition to viscosin deficient cells, also cells of the viscosin+ strain of P. fluorescens SBW25 were examined. The viscosin+ strain was used to study aerosolization efficiency in comparison to the viscosin deficient strain as well as the partitioning of viscosin between bulk water and surface water when viscosin was produced by the strain itself.
In addition, I examined how bacterial cell viability and enrichment in bubbles was affected by the cells ability to produce viscosin or not using Flow Cytometry.

Antagonistic interaction between Renicola roscovita and Himasthla elongata (Trematoda) in the common periwinkles, Littorina littorea

Andersen, Cecelie Kjer, 26.06.2018

Competition between species of trematodes co-existing within the same host is claimed to favour redia producing over sporocyst producing trematodes due to the formers mobile larvae, equipped with mouth and stomach, that allows for direct predation on the motionless sporocyst colony. Little is known about the outcome of such competition and how the species of trematodes adjust to the competitive environment. However, the resent idea of socially organized redial colonies are being qualified as a strategy to counteract parasite-parasite competition. Here, I investigate the species-specific responses of competition between the trematodes Himasthla elongata (redial larvae) and Renicola roscovita (sporocyst larvae) coinfecting the first intermediate host, the common periwinkle, Littorina littorea. In case of Himasthla, fitness of the colony (cercarial dimensions and longevity) was significantly reduced when coexisting with Renicola.
Renicola is highly pathogen to the host, which is evident as the energy content in the host, is significantly lower when infected by Renicola than by Himasthla alone. Making Renicola infections a threat to the host survival and thereby the coexisting trematode Himasthla. The negative impact of a heterospecific competitor, Renicola, is counteracted by Himasthla by production of non-reproductive rediae (“soldiers”), which invade and ingest the sporocysts colony of Renicola from the inside (hyperparasitism). Presence of Himasthla displaced of the renicolid colony within the host abdomen and retarded development (colony size/maturity) and reduced fitness (size and longevity of cercariae). This illustrates asymmetrical intra-molluscan competition between the two trematode species, related to their different life histories. However, even though the redial producing Himasthla is superior in its defending strategy, full elimination of the competing renicolid sporocyst colony before the completion of the latter’s life cycle is not effectuated.

A study of animal venoms

Sørensen, Jacob Lunding, 25.06.2018


Part A: Characterization of a putative cysteine-rich venom protease

The putative cysteine-rich venom protease (PVP) was partially purified by gel chromatography, with only slight contamination as determined by mass spectrometry. The function of PVP was investigated using various activity-based assays and the results suggest that PVP is either an inactive protease, a highly specific protease or does not have proteolytic activity at all. Furthermore, a fraction of the total venom PVP appears to be homogenously N-glycosylated. For the first time, the protein concentration of Acanthoscurria geniculata venom was determined by amino acid analysis. This is the first time the protein concentration of any spider venom has been reported. Lastly, the amino acid analysis suggests that the venom might contain free glutamate.

Part B: Unveiling the venom proteome of the pit viper, Cryptelytrops venustus

The venom proteome of Cryptelytrops venustus was characterized for the first time by SWATH-MS, a novel method in the field of snake venom proteomics. The venom contains proteins belonging to ten protein families: Phospholipase A2 enzymes (PLA2), snake venom metalloproteinases (SVMP), snake venom serine proteases, snake venom C-type lectins, disintegrins (DIS), cysteine-rich secretory proteins, L-amino acid oxidases, bradykinin-potentiating and C-type natriuretic peptides, 5’-nucleotidases and phosphodiesterases, but is dominated by PLA2 enzymes and SVMPs. Comparison of C. venustus and C. purpureomaculatus venom revealed substantial intragenus variation in relative protein family abundance and depart dramatically in their respective PLA2 complement. DISs were found to be unique to C. venustus venom, while the remaining nine protein families were represented in both venoms. Additionally, intraspecies venom variation was shown to be significant among three siblings. For the first time, snake venom protein concentration was determined by amino acid analysis, the golden standard in protein and peptide quantitation.

Interaktion mellem stress, luftåndingsadfærd og de fysiologiske stressmarkører i Pangasianodon hypophthalmus

Jeppesen, Sofie Skafsgård, 25.06.2018

Stress er en gennemgående del af det at være i live, hvilket der er blevet udviklet mekanismer til at tilpasse og overkomme. Hvorledes individet responderer på stresspåvirkninger af forskellig forekomst, er betydende for individets overlevelse og populationens reproduktive kapacitet. Igennem denne specialerapport redegøres der for den generelle stressfysiologi med en kobling til fakultativ luftåndende fisk og det trade-off, der er mellem luftånding og opfattet prædationsfare. Formålet med det eksperimentelle studie var at undersøge hvorvidt luftåndingsadfærd vil blive påvirket af udskillelsen af catecholaminer under stress, forårsaget af opfattet prædationsfare. Samt hvorvidt frygt var associeret med et adrenerg peak med stigning af adrenalin og noradrenalin. Studiet viste, at et stressmoment med forstyrrelse af fiskenet forårsagede øgning af luftåndingsfrekvensen, hvormed individet luftåndende væsentlig mere. Dette var koblet til en kraftig adrenerg stigning, med en ligeledes øgning i alle fysiologiske parametre, såsom catecholaminer, cortisol, glukose og laktat. Dette viser, hvorledes stress og udskillelsen af catecholaminer kan modificere luftåndingsfrekvensen, afhængig af intensiteten og typen af stressor.

Impact of Freshwater Seepage on Microbial Community Composition in Marine Sediment

Nádházi, Marie Høgsberg, 21.06.2018

Salinity is known to influence microbial community composition and diversity, yet detailed knowledge on how salinity and associated sulfate availability affect microbial structures in marine sediments is lacking. In this study we investigated the size and composition of the microbial community over salinity gradients associated with two freshwater seep pockmarks in a marine sediment (Limfjorden Denmark). Pockmarks provide a unique opportunity to study such changes within a small area with the same overlying water body. Ten sediment cores were collected by Rumohr lot coring in a transect bridging the two pockmarks. Porewater concentrations showed that chloride and sulfate decreased abruptly within the first 10 cm of the freshwater-influenced sediment and porewater concentrations of methane peaked at 25 cm depth. Outside the pockmarks sulfate concentrations decrease more slowly and methane concentrations remained low throughout the core with an inferred sulfate-methane transition zone at 50-60 cm depth. Quantification of bacterial and archaeal 16S rRNA gene copies in DNA extracted from the sediment by qPCR showed that bacteria and archaea were most abundant inside pockmarks while qPCR quantification of dsrB genes indicated that the abundance of sulfate-reducing microorganisms was undifferentiated between freshwater-influenced and marine sediments. As inferred from 16S rRNA gene amplicon sequencing the relative abundance of methanogens and anaerobic methanotrophs (ANME) was elevated inside pockmarks. Combined with the methane and sulfate data this suggest that methanogenesis was the predominant mineralization pathway inside pockmarks. The microbial community structure differed substantially between sites inside and outside pockmarks. Inside pockmarks uncultured genus level groups including Deltaproteobacteria Sva0485 and Bacteriodetes vandinHA17 increased in abundance as well as several uncultured members of Proteobacteria whereas at stations between pockmarks Desulfatiglans, Desulfobulbus and SEEP-SRB1 dominated. The archaea community was dominated by the subcluster ANME-2a/b, and the methanogenic genera Methanoregula and Methanoseata in the freshwater influenced pockmark sediment whereas Marine Benthic Group D and DHVEG-1 and ANME-1a/b dominated sediments outside pockmarks. Methanogenesis and AOM seemed to be important processes at the station with the highest flow of freshwater even though methane did not accumulate here indicating the presence of a “cryptic” methane cycle. Deep biosphere groups Chloroflexi, Bathyarchaeota (MCG), Atribacteria and Marine Benthic Group D (MBG-D) were present in stations between pockmarks but decreased in relative abundance in pockmark sediments. NMDS and CCA analysis showed that the species-level composition was similar in the surface sediments of all sites but with increasing depth the species-level composition diverged where the species-level composition in pockmarks correlated with porewater methane concentrations whereas species-level composition between pockmarks correlated with sulfate concentrations. The freshwater seepage in pockmarks has an extensive influence on the microbial composition and presumably also on the function of microbial communities. This relationship is observed at even small levels of freshwater seepage which seems to effectively override the marine imprint on the microbial community structure of sediment.

Diversity of fungi associated with the social spider Stegodyphus dumicola

Elberg, Christine, 21.06.2018

The social spider Stegodyphus dumicola has the lowest genetic diversity of any know species. Despite of this low genetic diversity leading to a poor immune response and the fact that they have a high risk of disease transmission they are still found in big parts of South Africa. This could be explained by a symbiotic relationship with a microorganism like a fungus. To investigate this the fungus diversity of Stegodyphus dumicola was examined using cultivation-dependent and cultivation-independent methods. Nest material from three different populations of Stegodyphus dumicola was sequenced and isolated from. This showed a clear population pattern meaning that nests from the same populations had the same fungus community. All isolates were tested for antimicrobial activity against Staphylococcus epidermidis, Pseudomonas putida, Escherichia coli and Bacillus subtilis using a disk-diffusion assay and an agar-plug assay. In total, 27 fungi showed some degree antimicrobial activity against the test bacteria indicating that some symbionts could affect Stegodyphus dumicola ability to fight pathogens.

Why insects die from anoxia: How anoxia affects energy, water, ion and pH balance

Ravn, Mathias, Vilsgaard, 21.06.2018

All animals rely on oxygen availability to produce ATP, but insects generally tolerate complete oxygen deprivation (anoxia) for considerable time. When exposed to anoxia, most insects rapidly go into a defensive hypometabolic coma from which they can recover when exposed to normoxia again. However, prolonged anoxic bouts eventually lead to death in insects like any other animal. During anoxic coma in insects, energy, ion and pH homeostasis and possibly water homeostasis is disrupted. However, it is not known how fast and to what degree each of the parameters are disrupted compared to each other or how quickly they recover. Further, it has not been investigated which disruptions are the primary source of tissue damage. Here I show in the migratory locust (Locusta migratoria) that prolonged anoxic exposures are associated with increased recovery time, decreased survival, and rapidly disrupted ion, energy, pH, and water homeostasis, and I show which disruptions are associated with tissue damage. I found that locusts could not fully recover after 4 hours of anoxia at 30 °C, and at this point hemolymph [K+] and [Na+] had elevated 5-fold and decreased 2-fold respectively, muscle [ATP] had decreased to ≤3% of normoxic values, hemolymph pH had dropped 0.8 units from 7.3 to 6.5, and hemolymph water content was halved. Furthermore, I demonstrate that the isolated and combined effects of hyperkalemia, acidosis and anoxia without hyperkalemia and acidosis all cause muscle tissue damage in vitro, and that to equally large degrees. These results suggest that anoxia causes physiological disruptions that are leading to anoxic injury, though the mechanisms behind are still unknown.

Exploring telemetry as a novel method to study behavioral thermoregulation in insects

Ørskov, Christian, 19.06.2018

Behavioral thermoregulation in insects has been extensively studied in locust species including the migratory locust (Locusta migratoria) which is able to regulate body temperature by seeking suitable microclimates. Such studies have for example demonstrated behavioral fever in specimens inoculated with pathogens while other studies have shown how the transition from fasting to feeding changes thermal preferences. Most studies of insect thermoregulation in the field are, however, confounded to daytime observations using invasive thermocouples. In the present study I demonstrate that minute radio-transmitters represent an alternative and non-invasive method to study insect thermoregulation and discuss how this method can be used to study the thermal behavior of free-ranging animals for extended periods. Specifically, I established a close correlation between temperature recordings from implanted thermocouples and externally mounted radio transmitters. The following set of experiments were performed to demonstrate that animals with radio transmitters display “normal” behavior in the form of behavioral fever as a response to inoculation of a fungal pathogen and in other animals we demonstrated “normal” thermophilic behavior associated with feeding. Finally, a set of pilot experiments were conducted on a different orthopteran (Gryllus campestris) to demonstrate the applicability of the system in the field. These crickets are ground-dwellers and remain close to their burrows during the day, which makes them ideal model organism as they rarely move out of the range of the receiver. This study represents the first step toward the implementation of radio-telemetry in studies of behavioral thermoregulation on large insects.

Faunaøkologi for den lille danske ø Dræet

Bak, Emil, 13.06.2018

Little is known about the distribution and conservation status of Danish arthropods and even less so for those inhabiting Danish islets. Knowledge of species distribution and habitat choice is of key importance to make informed management plans for conservation efforts in the future. Thus, there is a substantial need for baseline studies on Danish arthropods’ distribution and ways of classifying habitats based on their arthropod fauna. 
In this study various pitfall trapping methods were used to determine the arthropod fauna of the Danish islet Dræet, located in the northern archipelago of Fyn at Æbelø. Trapping transects were arranged around the perimeter of the islet perpendicular to the vegetational coastline going inland. The collecting of arthropod fauna was carried out three times over one growing season. A concurrent study classified flora and floral habitats for most of the included transects of this study. The experimental setup allowed an examination of fauna distribution and habitat choice both temporally and spatially.
A total of 277 taxa were documented from the orders: Araneae, Opiliones, Coleoptera, Hemiptera and Hymenoptera, of which 204 were determined to species level. It was shown that floral habitats to a large extent also reproduce the variation in arthropod community composition. This was the case for all the observed floral habitats: reedbed, salt marsh, beach ridge, fixed dune and grassland. Habitats varied in species richness, species composition, trophic levels ratios, and predator/prey ratios. Furthermore, overlapping zones between floral habitats were identified as they had a mixed arthropod species pool from both their neighbouring habitats and consequently a higher species richness which supports the usage of floral habitats as descriptors for arthropod habitats. There was no direct effect of proximity to the sea on the arthropod fauna, however indirect effects of sea proximity on the fauna were seen through alteration of floral habitats.
Thus, this study emphasizes that floral habitats can be used to describe arthropod habitats. Thus, protected floral habitats of the EU habitats directive can then be used as units for future management and conservation of arthropod fauna.          

Undersøgelse af flora kyst-land gradienten på øen Dræet

Holck, Marc Hammer, 13.06.2018

Species richness, composition and species traits are analyzed along a 120-meter-long coast-land gradient on the island Dræet in Denmark. The purpose is to describe how these factors change when you move from the coast to inland. In addition, habitat types for the island will be defined using the floral composition and then analyzed for species richness, composition and species traits as well. Lastly phylogenetic structure of the community will be examined, and each trait will be tested for phylogenetic signal.
Both species richness and composition changed along the coast-land gradient. Species richness peaked at the coastal distance 15-30 meters with more than 50 different species, while the distance 1 meter had the lowest richness with 16 different species in total. The fact that species richness peaks at 15-30 meters is probably due to the fact that this distance has the largest environmental variance, which allows for more niches and hence more kinds of species. Another reason could be that species found at the coast and inland both are capable of dispersing to the distance 15-30 meter, and hence that distance contains more kinds of species. The composition of species changed as well from coast to land, and a core of species was found near the coast and another inland. However, after 15-30 meters only a few new species appear that have not already been observed at an earlier distance closer to the sea. These changes in the community are most likely caused by changes in the abiotic environment, especially humidity seems to be an important factor in determining the composition of species, but the biotic interactions and the dispersal ability of the species of course also have an influence on the structuring of the community. The traits of the species had for the most part a coast-land gradient as well, and especially plants at 1-5 meters were frequently different from the plants at other distances with respect to their traits.
In addition, the composition of the species community was used to define six different habitat types on the island. Three of these were found close to the sea, while the other three were found further inland. The two habitat types with the highest species richness were grassland and fixed dune with around 50 different species each.
No phylogenetic structure was observed in the community. However, there was a slight tendency to phylogenetic clustering in a few grassland sites. For species traits a phylogenetic signal was found in several binary traits, which means that the species that are closely related share similarities in their traits. Consequently, the conclusion is that a coast-land gradient exists both in species richness, composition and species traits, and that this gradient creates a heterogeneous environment on Dræet, that leads to a diverse floral community.

Predicting regime shifts and crashing states using a coupled hydrodynamic-biogeochemical model for shallow Lake Hinge

Andersen, Tobias Kuhlmann, 13.06.2018

In recent years, considerable efforts have been made to restore temperate shallow lakes from a turbid regime dominated by phytoplankton to a macrophyte dominated regime with its ability to stabilize clear-water conditions. Models with simplified physical representations have so far been used to show the presence drastic regime shifts with hysteresis effects between these regimes, and to predict external nutrient thresholds for regimes shifts. I hypothesize that model predictions of regime shifts would become more gradual, if models would take into account depth heterogeneity of the system being modelled due to, among other factors, the possibility of a faster re-establishment of submerged macrophytes. To test this hypothesis, a bifurcation analysis was undertaken with the 1D coupled hydrodynamic-biogeochemical model complex GOTM-FABM-PCLake. The model was first calibrated and validated against a comprehensive dataset covering two consecutive seven-year periods for the shallow, eutrophic Lake Hinge, Denmark. The model simulations generally showed good agreements with observed data for water temperature, nutrients (TN, NO3, NH4, TP, PO4) and chlorophyll a concentrations. The bifurcation analysis revealed that the model is able to produce an intermediate, crashing regime with late summer cyanobacteria peaks in between the clear-water regime, with highest macrophyte coverage, and a turbid diatom-dominated regime. Submerged macrophyte biomass and depth limit as well as chl-a responded more gradual over time to a reduction in external phosphorus load than previously simulated in comparable model studies. As managers wish to determine external nutrient load thresholds to achieve clear-water conditions in shallow lakes, this study emphasizes the need to include depth heterogeneity in the model structure and demonstrates GOTM-FABM-PCLake as a useful management tool for quantifying required nutrient load reductions.

The effect of a recovery period after chemical stress on Folsomia Candidas tolerance of a subsequent stressor

Mikkelsen, Gustav Holm, 08.06.2018

Økotoksikologiske standardtests af miljøfarlige stoffer benytter sig af en enkel og let reproducerbar metode, der tillader sammenligning mellem forskellige laboratorier. I disse standardtests bliver effekten af et enkelt kemikalie testet, som regel på forsøgsdyr, der lever under optimale forhold og med en høj fitness. Mens disse standardtests har åbenlyse fordele, udelukker de dog en række faktorer, som har vist sig at påvirke jordfauna. Blandt disse faktorer kan nævnes naturlige stressorer, herunder varme, tørke og sult, kemiske blandinger samt gentagne eksponeringer og tiden mellem disse. Der forekommer desuden en mængde interaktioner mellem disse stressorer, som potentielt synergetisk kan sænke jordfaunaens tolerance over for en efterfølgende stressfaktor. Inden for dette emne er der stadig store mangler på viden, især vedrørende varmes interaktion med forskellige miljøfarlige stoffer og effekten af en periode mellem eksponering til kemikalier og en efterfølgende stressfaktor.
Formålet med dette speciale er at undersøge effekten af en periode mellem kemikaliestress og en efterfølgende varmestress eller kemikaliestress. Desuden undersøges effekten af eksponeringsperioden, samt de molekylære responser til kemikalier. Til disse forsøg blev springhalen Folsomia candida anvendt som modelorganisme, mens stofferne nonylphenol, phenanthrene og ivermectin var modelstoffer.
Resultaterne af forsøgene indikerede en stærk synergetisk effekt mellem varmestress og nonylphenol eller phenanthrene. Det blev desuden bestemt, at phenanthrene og nonylphenol sænkede organismens varmetolerance i henholdsvis 7 og 14 dage efter eksponeringen. Påvirkningen af phenanthrene på varmetolerance korresponderede med metaboliseringen eller udskillelsen af stoffet, mens nonylphenol påvirkede organismer i en betydelig tid, efter stoffet var udskilt eller metaboliseret.
Målingen af de molekylære responser gav ikke et tydeligt billede af dyrenes respons på kemisk stress. Eksponeringstiden til nonylphenol og phenanthrene viste sig at have en stor påvirkning af effekten af disse stoffer, idet begge stoffers toksicitet steg betydeligt i de længere forsøg.
Disse forsøg indikerer at toksiciteten af et miljøfarligt stof kan blive betydeligt underestimeret, da varme kan interagere synergetisk med stoffet. Perioden mellem kemisk stress og naturlig stress er desuden ekstremt vigtig for jordfaunas evne til at håndtere den efterfølge stress. Derfor bør disse faktorer ikke blive udelukket af fremtidlig risikovurdering. Det blev desuden vist at en kort eksponeringsperiode ikke kan erstatte perioden på 28 dage, som er standard i risikovurdering, da en periode på 7 dage underestimerer toksiciteten af kemikalier.

Management strategies for Grey wolf (Canis lupus) in Denmark

Mikkelsen, Caroline Vestergaard, 06.06.2018

The Grey wolf (Canis lupus) have historically been distributed in most of Europe (Fechter & Storch, 2014). In the last decades the wolves have been recolonizing historical areas, due to protection of the Grey wolf and their habitats. Almost 200 years after the last wolf was shot and killed in Denmark, wolves are migrating back to Denmark from Germany and Poland. With this development in the Central European Grey wolf population, more wolves are expected to migrate to Denmark in the future (Fechter & Storch, 2014). In 2017 Denmark experienced its first reproducing pair and it is expected that they will reproduce once again in 2018 (Sunde & Olsen 2018). The return of the Grey wolf in many European countries – including Denmark – have created many conflicts between locals and the government (Theodorakea et al. 2016; Dickman 2010). The present management plan for wolves in Denmark addresses plausible scenarios with wolves in Denmark. The Grey wolf in Denmark is a new situation. The knowledge and experience available in the present management plan for the Grey wolf in Denmark, is based on experience and knowledge from other European countries. Adaptive management is a process where the management plan can adapt to new knowledge and experiences, hence making the management plan flexible (Madsen 2014). A method that can be used in adaptive management planning is “action research”. This is a method where the participants decide the agenda and determines fully or partially how the process develops (Fuglsang et al. 2012).
In this study, the biology, ecology and social structure is described. Furthermore, it is discussed why management planning of conflict species is necessary. As an example, ‘Project Wolf-dialogue’ is described, as a possible tool in adaptive management.  Participants have together formed different questions, which have been answered by relevant scientists and experts. Furthermore, the participants have made different suggestions to a future management plan (Maarbjerg et al. 2018). The main goal in ‘Project Wolf-dialogue’ was to test if the critical-utopian dialogue method can be used to create a constructive dialogue according to the Danish wolf-conflicts. The results show that the participants changed their attitude towards scientists and the managing authorities. They have greater confidence in the authorities and scientists. The participants also change their attitude of the grey wolf towards a more positive attitude. The conclusion is, that it does make sense listening to local’s opinions and experiences with wolves. However, there are still challenges that need to be investigated in the context of conducting dialogue projects in the future.

Development of Anaesthesia in Reptiles

Iversen, Sofie Hahn, 23.02.2018

Objective 1. To Identify an effective dose of medetomidine and ketamine in combination, and to investigate the suitability of these anaesthetics for induction and/or anaesthesia in snakes. 2. To investigate the isolated and combined physiological and cardiovascular effects of a clinically relevant dose, and to study the effect of a dose too low for visible sedative effects, yet still elicit physiological responses.
Animals 1. Six healthy juvenile ball pythons (Python regius). 2. Eleven healthy adult ball pythons.
Methods 1. Four combinations of medetomidine and ketamine (0.2, 0.2, 0.3, and 0.3 mg kg-1 medetomidine combined with 5, 10, 5, and 10 mg kg-1 ketamine, respectively) was injected, and anaesthetic depth was based on the following parameters: spontaneous movement, head support, jaw tone, body tone, and righting reflex. 2. Two doses of anaesthetics (0.1 and 0.3 mg kg-1 medetomidine both combined with 5 mg kg-1 ketamine) were administered IM to pythons, and HR and MAP were obtained from a catheter placed in the vertebral artery. Furthermore, blood samples were taken at different time points to measure PaCO2 and PaO2 along with pH and lactate levels. Lastly, influence of handling was investigated by IM injections of saline, mimicking the administration of anaesthetics.
Results 1. The effects were clearly dose-dependent, but there was considerable variation amongst individuals. 2. Tachycardia and hypertension resulted from of both dosages of medetomidine and ketamine. After 20-30 min, bradycardia occurred. MAP remained above base-line. Furthermore, hand­ling caused significant tachycardia and hypertension.
Conclusions The combinations of medetomidine and ketamine administered in the present study only provided sedation adequate for immobilisation and minor manipulations and was not suited for surgical procedures. Caution is needed for this combination due to individual variation and the physiological disturbances.

The effect of long-term hypercapnia on the metabolism and growth in striped catfish (Pangasianodon hypophthalmus)

Nielsen, Tine Haslam, 19.02.2018

Hypercapnia in aquacultures have been associated with negative effects such as a reduced food consumption, reduced aerobic scope, and reduced growth in several water-breathing species. Though, the effects of hypercapnia on air-breathing fish is limited. In the present study, standard metabolic rate, maximum metabolic rate, and the partitioning of air-breathing in P. hypophthalmus long-term exposure to 3% CO2 and an acute exposure to 3% CO2, were estimated using intermittent closed respirometry combined with a chase protocol. Further, two growth experiments were conducted and blood samples were collected to determine the effects of hypercapnia on haematocrit, plasma pH, and pH regulation. Standard metabolic rate, routine metabolic rate, maximum metabolic rate, and aerobic scope remained unchanged when exposed to hypercapnia. Likewise, no difference in growth was found. The air-breathing was significantly higher for the hypercapnic group measured in hypercapnia with 18.608 ± 2.820%, compared to the normocapnic group measured in normocapnia and the hypercapnic group measured in normocapnia which was 8.902 ± 2.410% and 8.670 ± 2.311% respectively. The bicarbonate level in the hypercapnic group was significantly higher than in the normocapnic group (33.462 mM difference, p: <0.01) and the chloride concentration was equivalent smaller (38.200 mM difference, p: <0.01). There was no difference in pH nor in haematocrit. This suggests that P. hypophthalmus is able to fully compensate the decrease in pH that hypercapnia would cause without any consequences for growth or metabolism, which makes it an excellent fish for aquaculture.

Udholdenhedspræstationsevne og okklusionstræning

Bartholomæussen, Jeppe, 24.01.2018, speciale

Ilttransport i blodet hos hvirveldyr med fokus på krybdyr

Ravn Malling, Martin, 22.01.2018, speciale

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