feeding experiments
Recently Published Documents

Doliolids often form massive blooms during upwelling conditions in sub-tropical shelves. However, their trophic role, including their nutritious fecal pellets, in pelagic marine food webs remains poorly investigated. In this study, we performed three independent feeding experiments of cultured Dolioletta gegenbauri and used qPCR analysis and 16S rRNA metabarcoding to characterize the microbial community associated with full gut (FG) and empty (EG) doliolids, fresh (FP2Hrs) and senescing (FP24Hrs) fecal pellets, and the surrounding natural seawater (SW). Bacterial abundance (i.e., 16S rRNA gene copies) in EG samples was an order of magnitude lower than in SW and three orders lower than in FP24Hrs. Diversity analyses, based on the 16S rRNA metabarcoding data, supported a richer microbial community in SW, FP2Hrs, FP24Hrs, and FG samples. Furthermore, microbial community structure was determined by sample type, with FG samples appearing more similar to either FP2Hrs or FP24Hrs. These patterns resulted from the higher number of shared ASVs and consequently the contribution of similar major bacterial taxa (e.g., Rhodobacteraceae, Pirellulaceae). These observations support the hypothesis that there are significant ecological and trophic interactions between D. gegenbauri and the ocean microbiome. Predicted gene function recovered many genes related to key processes in the marine environment and supported greater similarity between FP2Hrs, FP24Hrs, and FG samples. These observations suggest that pelagic marine bacteria are utilized by D. gegenbauri to digest captured prey particles, and the subsequent release of fecal pellets supports the rapid proliferation of distinct microbial communities which likely influence key biogeochemical processes in the ocean.

Abstract Large herbivores can disperse seeds over long distances through endozoochory. The Korean water deer (Hydropotes inermis argyropus), an internationally vulnerable species but locally considered a vermin, is a potential endozoochorous seed dispersal vector. In this study, feeding experiments were conducted to test the efficiency of seed dispersal through gut ingestion by the Korean water deer, its temporal pattern and the effect of gut passage on seed recovery and germination rate. Eight plant species, including species that formerly germinated from its faeces, were used to feed three Korean water deer. Once the deer had consumed all the provided seeds, their faeces were collected after 24, 48, 72 and 96 h. The collected faeces were air-dried, and the number of seeds retrieved from the faeces was counted every 24 h (0–24, 24–48, 48–72 and 72–96 h). Among the eight plant species, six species were retrieved with intact seeds. Panicum bisulcatum had the highest recovery rate of 33.7%, followed by Amaranthus mangostanus (24.5%) and Chenopodium album (14.4%). Most of the seeds were recovered within the 24–48 h time interval. Germination tests were conducted on the ingested and uningested seeds for the four species which had a sufficient recovery rate. The effects of gut passage on seed germination differed according to plant species. The germination rate substantially decreased after gut passage. The results suggest that the Korean water deer can disperse seeds, potentially over long distances albeit at a high cost of low seed recovery and germination rate.

The transition from lean to obese states involves systemic metabolic remodeling that impacts insulin sensitivity, lipid partitioning, inflammation, and glycemic control. Here, we have taken a pharmacological approach to test the role of a nutrient-regulated chromatin modifier, lysine-specific demethylase (LSD1), in obesity-associated metabolic reprogramming. We show that systemic administration of an LSD1 inhibitor (GSK-LSD1) reduces food intake and body weight, ameliorates non-alcoholic fatty liver disease (NAFLD), and improves insulin sensitivity and glycemic control in mouse models of obesity. GSK-LSD1 has little effect on systemic metabolism of lean mice, suggesting LSD1 has a context-dependent role in promoting maladaptive changes in obesity. Analysis of insulin target tissues identified white adipose tissue as the major site of insulin sensitization by GSK-LSD1, where it reduces adipocyte inflammation and lipolysis. We demonstrate that GSK-LSD1 reverses NAFLD in a non-hepatocyte-autonomous manner, suggesting an indirect mechanism via inhibition of adipocyte lipolysis and subsequent effects on lipid partitioning. Pair-feeding experiments further revealed that effects of GSK-LSD1 on hyperglycemia and NAFLD are not a consequence of reduced food intake and weight loss. These findings suggest that targeting LSD1 could be a strategy for treatment of obesity and its associated complications including type 2 diabetes and NAFLD.

<p>Temperate rocky shores around the world are characterised by so-called ‘universal’ zonation. An interesting exception to this rule can be seen along the shores of Wellington’s South Coast where there is a virtual absence of mussels and poorly developed rocky shore intertidal community. Yet just kilometres away in Wellington Harbour there is a fully developed intertidal community, including extensive multi-species mussel beds. This thesis aims to determine if the quality of seston is limiting the presence of mussels on Wellington’s South Coast. We now have the technology to see what types of particles the mussels are selecting in low and high quality seston conditions using a FlowCAM that allows identification of particle types and their physical properties.  This study compared environmental data for Wellington Harbour (seston-rich) and the South Coast (seston-poor). These data included chlorophyll a, turbidity and suspended sediment concentrations and were collected by CTD and satellite remote sensing. Mussel feeding experiments took place under a high and low quality diet during summer, autumn and winter using Perna canaliculus and Mytilus galloprovincialis. The physiological responses recorded were clearance rate, absorption efficiency and net energy balance for individual mussels. Environmental variables recorded were total particulate matter, particulate organic matter and percent organic matter. Water samples were collected during the feeding experiments and processed using the FlowCAM. By comparing the control chambers to chambers that had mussels feeding in them it was possible to see what particles the mussels were selecting.  The environmental variables revealed that Wellington Harbour had a much higher quality seston whereas in Cook Strait the seston quality was too low for mussels to be able to inhabit, as the chlorophyll a concentrations did not reach the required levels for mussel growth. Perna canaliculus and Mytilus galloprovincialis both showed physiological responses that would allow them to grow in Cook Strait waters, both species had positive absorption efficiencies and net energy balances. These responses were greater in the high quality diet in the enriched pond water in Nelson during summer and winter. The FlowCAM analysis revealed an inter-specific difference in preferential particle selection, which varied as a function of site and season. With more particles being preferentially selected in the high quality diet compared to when the mussels were feeding on Cook Strait seawater. This new information of particle selection helps to determine why mussels are absent from Wellington’s South Coast and contributes to the extensive information on mussel feeding.</p>

<p>Temperate rocky shores around the world are characterised by so-called ‘universal’ zonation. An interesting exception to this rule can be seen along the shores of Wellington’s South Coast where there is a virtual absence of mussels and poorly developed rocky shore intertidal community. Yet just kilometres away in Wellington Harbour there is a fully developed intertidal community, including extensive multi-species mussel beds. This thesis aims to determine if the quality of seston is limiting the presence of mussels on Wellington’s South Coast. We now have the technology to see what types of particles the mussels are selecting in low and high quality seston conditions using a FlowCAM that allows identification of particle types and their physical properties.  This study compared environmental data for Wellington Harbour (seston-rich) and the South Coast (seston-poor). These data included chlorophyll a, turbidity and suspended sediment concentrations and were collected by CTD and satellite remote sensing. Mussel feeding experiments took place under a high and low quality diet during summer, autumn and winter using Perna canaliculus and Mytilus galloprovincialis. The physiological responses recorded were clearance rate, absorption efficiency and net energy balance for individual mussels. Environmental variables recorded were total particulate matter, particulate organic matter and percent organic matter. Water samples were collected during the feeding experiments and processed using the FlowCAM. By comparing the control chambers to chambers that had mussels feeding in them it was possible to see what particles the mussels were selecting.  The environmental variables revealed that Wellington Harbour had a much higher quality seston whereas in Cook Strait the seston quality was too low for mussels to be able to inhabit, as the chlorophyll a concentrations did not reach the required levels for mussel growth. Perna canaliculus and Mytilus galloprovincialis both showed physiological responses that would allow them to grow in Cook Strait waters, both species had positive absorption efficiencies and net energy balances. These responses were greater in the high quality diet in the enriched pond water in Nelson during summer and winter. The FlowCAM analysis revealed an inter-specific difference in preferential particle selection, which varied as a function of site and season. With more particles being preferentially selected in the high quality diet compared to when the mussels were feeding on Cook Strait seawater. This new information of particle selection helps to determine why mussels are absent from Wellington’s South Coast and contributes to the extensive information on mussel feeding.</p>

Nearly four decades after the first applications of strontium isotope analyses in archaeology and paleoecology research, it could be said that we are entering a “Golden Age”. Here, we reflect on major past developments and current strengths in strontium isotope research, as well as speculate on future directions. We review (1) the currently limited number of (but much needed) controlled feeding experiments, (2) recent advances in isoscape mapping and spatial assignment, and (3) the strength of multi-proxy approaches (including both the integration of strontium isotopes with other isotope systems and complementary techniques such as ancient DNA analyses). We also explore the integration of strontium isotope research with other types of paleoecological or archaeology data, as well as with evidence and interpretative frameworks from other fields (such as conservation ecology, conservation paleobiology or history). This blending is critical as we seek to advance the field beyond simply distinguishing local or relatively sedentary individuals from those that were non-local or highly mobile. We finish with a call for future research centered on balancing methodological developments and novel applications with critical self-reflection, deeper theoretical considerations and cross-disciplinarity.

Abstract This study was conducted to evaluate the difference in ruminal degradability by the degree of gelatinization of corn grain. The treatments were Control (whole corn grain), T1 (70% gelatinized corn grain steam flake), and T2 (30% gelatinized corn grain steam flake). Corn grain steam flaked for T1 was produced by a pressurized steam chamber for a longer time than T2. For this reason, the thickness of T1 and T2 was 1.5 and 2.5mm on average, respectively. Two Holstein cows (BW.405±15.4kg, 26.5±12 months) fitted with ruminal cannula were fed 4 kg of tall fescue and 3 kg of a formulated concentrate mix. Immediately after morning feeding, the nylon bags containing the sample from all treatments were incubated in the ruminal ventral sac for 0, 2, 4, 8, 12, 18, 24, 36, and 48h. At 0h of incubation, the DM degradability of T1 (16.70%) was higher (P&lt; 0.05) than Control (9.74%) and T2 (12.00%). The degradability of both Control and T2 slightly increased from 4 (23.08 and 27.57%) to 18h (36.65 and 35.52%), exponentially increased from 18 to 48h. On the other hand, the degradability for T1 exponentially increased from 2 (28.74%) to 18h (77.31%), only slightly increased thereafter. The final degradability (48h) of Control, T1, and T2 were 78.07, 89.20, and 84.86%, respectively (P&lt; 0.05). The fraction a of DM degradability for T1 (24.29%) was higher than Control (2.26%) and T2 (6.26%) (P&lt; 0.05). The effective degradability (ED) of T1 (75.31%) was higher (P&lt; 0.05) than Control (57.42%) and T2 (60.86%). Therefore, this study demonstrated that 70% gelatinized corn grain steam flake showed a higher rate of ruminal degradability than other treatments. Thus, it is necessary to determine how these differences affect ruminant productivity through additional feeding experiments.

Abstract New technologies have enabled autonomous measurement of intake and feeding behavior of pen-fed animals and this has piqued interest in utilizing similar technologies in grazing experiments. Various feeding systems are currently available, but individual supplementation and feeding experiments have been conducted for years using individual feeding stanchions, which are the lowest level of technology for measuring supplement intake. These experiments are laborious as they require animals to be trained and acclimated, gathered at each feeding, and sorted into individual stalls for supplementation—thereby disrupting the animals grazing activities. In the mid-1980s Calan Gate systems (American Calan; Northwood, NH) became popular in pasture supplementation experiments, but still have many of the same disadvantages. Newer, more automated systems, reduce labor and possibly have less disruption of the animal’s grazing behavior, but are reliant on the animal’s willingness to use the system and ability to access it when more dominant peers are present. Individuals also do not always follow the “averages”-based rules we often hold true and behave differently in groups. Recent research with automatic feeders show steers consumed average of 60% of the potential supplement with supplement intake CVs of 50 to 100%. These technologies lead many to question the paradigm of experimental units in experimental designs. The experimental unit is defined as the smallest independently assigned unit to which the treatment is applied. This definition of experimental unit is somewhat limiting when taken to the extreme, but still applies well for experiments utilizing individual animal feeding, regardless of the level of technology involved. In many cases where the aforementioned technologies are used, the individual animal can be both the observational and experimental unit. This symposia presentation will discuss attributes of different feeding options and the implications on study design, experimental power, and the designated experimental unit.

AbstractSclareol, an antifungal specialized metabolite produced by clary sage, Salvia sclarea, is the starting plant natural molecule used for the hemisynthesis of the perfume ingredient ambroxide. Sclareol is mainly produced in clary sage flower calyces; however, the cellular localization of the sclareol biosynthesis remains unknown. To elucidate the site of sclareol biosynthesis, we analyzed its spatial distribution in the clary sage calyx epidermis using laser desorption/ionization mass spectrometry imaging (LDI–FTICR-MSI) and investigated the expression profile of sclareol biosynthesis genes in isolated glandular trichomes (GTs). We showed that sclareol specifically accumulates in GTs’ gland cells in which sclareol biosynthesis genes are strongly expressed. We next isolated a glabrous beardless mutant and demonstrate that more than 90% of the sclareol is produced by the large capitate GTs. Feeding experiments, using 1-13C-glucose, and specific enzyme inhibitors further revealed that the methylerythritol-phosphate (MEP) biosynthetic pathway is the main source of isopentenyl diphosphate (IPP) precursor used for the biosynthesis of sclareol. Our findings demonstrate that sclareol is an MEP-derived diterpene produced by large capitate GTs in clary sage emphasing the role of GTs as biofactories dedicated to the production of specialized metabolites.