Presence of anti-Neoparamoeba sp. antibodies in Tasmanian cultured Atlantic salmon, Salmo salar L

Previous studies have indicated that when Atlantic salmon, Salmo salar L., are exposed to Neoparamoeba sp. the fish produce anti-Neoparamoeba sp. antibodies. It appears unlikely that these antibodies elicit any specific protection against amoebic gill disease (AGD) as fish with demonstrable activities have been affected by AGD. Experiments were conducted on Atlantic salmon cultured throughout Tasmania to assess the natural production of antibodies towards Neoparamoeba sp. Fish were sampled from areas where AGD was prevalent and from areas where there had been no reported cases. An enzyme-linked immunosorbent assay (ELISA) was used to measure anti-Neoparamoeba sp. antibody activities in serum. All fish from sea water had antibody activities greater than the negative control fish, including fish from areas with no reported cases of AGD. Time trial samples indicated that time after transfer to sea water did not appear to be a significant (P > 0.05) factor in antibody activity, however location was (P < 0.05). There was no agreement (corrected kappa value, 0.16) between the ELISA result and the isolation of Neoparamoeba sp. from the gills of the same fish. The results suggest that Atlantic salmon in seawater culture in Tasmania produce anti-Neoparamoeba sp. antibodies regardless of infection history, suggesting the presence of Neoparamoeba sp. in the environment.     

Insights into an undescribed high-elevation lake (6,170 m a.s.l.) on Volcán Llullaillaco: A physical and microbiological view

1. High elevation lakes are extreme ecosystems and serve as sentinels of various global changes.
2. An expedition to Volcán Llullaillaco in 1996 discovered an unstudied high-elevation lake (6,170 m a.s.l.) that probably was formed as a result of the past eruptive events or climatic processes such as glacial retreat in the lake basin.
3. This article describes an initial physical characterization of the lake and its microbial communities derived from two sampling expeditions in 2013 and 2016.
4. The microbial community in the lake, with an area between 1.2 and 1.4 ha and a depth of 6.8 m, was dominated by Proteobacteria, Actinobacteria and Haloarchaea. In addition, 26 bacterial isolates were identified within the genera Subtercola, Xylophilus, Rhodanobacter, Mesorhizobium and Pseudomonas.
5. Lago Llullaillaco is one of the highest recorded lakes in the world, and this study highlights the unique microbial diversity of this aquatic ecosystem and the importance of its preservation to understand the complex biological processes under polyextreme conditions.

     

Taxonomic and functional macroinvertebrate diversity of high-altitude ponds in the Macun Cirque,Switzerland

1. Global environmental change is threatening freshwater biodiversity with ecological impacts predicted to be particularly severe in high-altitude regions. Despite this, an ecological understanding of high-altitude pond networks remains patchy, with only limited knowledge of the environmental and spatial predictors of taxonomic and functional diversity. Moreover, previous studies of pond ecosystems have focused primarily on taxonomic richness and largely overlooked functional diversity.
2. This study examined the influence of local environmental and spatial factors on taxonomic and functional α and β diversity (including the turnover and nestedness-resultant components) of 17 high-altitude (~2,500 m above sea level) pond macroinvertebrate communities, in the Macun Cirque, Switzerland.
3. Spatial processes (pond connectivity) were important drivers for taxonomic α diversity, while local environmental variables (pond permanence and surface area) were important determinants of functional α diversity. Species turnover was the most important component of β diversity for taxonomic composition, and functional composition demonstrated a nested spatial pattern.
4. Variation in taxonomic and functional composition (and the turnover and nestedness components of β diversity) were determined by local environmental variables despite the limited environmental gradients within the pond network. No significant effects of spatial variables on community composition were recorded for either facet of diversity, indicating that compositional variation was determined at a local scale. Water temperature, depth and pond permanence were consistently the most important measured drivers of diversity.
5. Given the importance of both spatial and environmental variables in structuring taxonomic and functional diversity, landscape-scale conservation and management activities that aim to improve or protect high-altitude freshwater biodiversity should focus on maintaining connectivity among ponds and environmental heterogeneity, particularly pond surface area, water depth, and hydroperiod. Understanding the mechanisms driving taxonomic and functional diversity will be critically important for the management and conservation of macroinvertebrate communities in high-altitude pond networks in the face of climatic warming.

     

Monitoring Indo-Pacific humpback dolphin occurrences in a highly urbanized estuary for informing conservation and management

1. The estuaries within the Pearl River Delta are sites for large-scale urban development and offshore construction. These projects have conservation stakeholders calling for more protection for the Indo-Pacific humpback dolphins whose habitat overlaps with current and proposed construction sites.
2. Efforts to improve impact assessments are hindered by the lack of baseline data and comprehensive understanding of how often the dolphins are present in areas near or within locations targeted for further development. The Modaomen Estuary within the Pearl River Delta is a good example of this, with little consideration for the dolphins as no data on their diurnal and seasonal occurrences within the estuary exist.
3. A passive acoustic monitoring system was deployed over a calendar year from October 2016 to September 2017 to monitor the presence of humpback dolphins in the Modaomen Estuary.
4. Results indicated that the estuary is an important area for humpback dolphins, with regular diel rhythms and seasonality in detection rates. For example, higher detections were seen during the wet season than during the dry season. However, there was no significant difference in detection rates between the flood and ebb tides, or between high and low tidal phases.
5. Since the Modaomen Estuary is targeted for further development in the near future, these data provide the rationale for resource management and consent processes to consider potential impacts on the dolphins, as well as to aid marine spatial planning and conservation measures.

     

Seasonal spatial distribution of juvenile lake sturgeon in Muskegon Lake,Michigan, USA

We examined seasonal spatial distribution and diel movements of juvenile lake sturgeon Acipenser fulvescens in Muskegon Lake, Michigan (a protected, drowned river mouth lake that links the Muskegon River to Lake Michigan). We surgically implanted ultrasonic tags in 20 juveniles (age 1–7) captured in gill nets to track their locations during August–December 2008/2009 and September 2010–October 2011. Most juveniles were observed ≤1.5 km from the mouth of the Muskegon River in Muskegon Lake at a mean depth of 7.5 m (SE = 1.3 m) during summer. In fall, juveniles moved away from the river mouth to the deepest part of Muskegon Lake and were observed at a mean depth of 15.8 m (SE = 1.3 m) during winter. The shift in spatial distribution coincided with fall turnover (i.e., loss of thermal stratification) and with changes in dissolved oxygen (DO) concentrations in the hypolimnion. During summer, DO concentrations in the hypolimnion were typically <4 mg·l^?1 in the deepest part of Muskegon Lake and DO concentrations at locations of tagged lake sturgeon were >7 mg·l^?1 in 94% of instances. Tracking in 2009 revealed no significant change in depth distribution or movement over the diel cycle. We only observed two tagged juveniles immigrating to Lake Michigan, suggesting that juveniles use Muskegon Lake for multiple years. Our results suggest that: (i) Muskegon Lake serves as an important nursery habitat for juvenile lake sturgeon that hatched in the Muskegon River before they enter Lake Michigan and (ii) seasonal changes in DO concentration in the hypolimnion likely affect the spatial distribution of juveniles in Muskegon Lake.     

Kinetics and postmucosal effects on urinary recovery of 5 intravenously administered sugars in healthy cats

The objective of this study was to describe the kinetics of urinary recovery and to evaluate the effects of postmucosal factors on urinary recovery of 5 intravenously administered saccharides. Ten cats received an isotonic sugar solution containing lactulose, rhamnose, xylose, methylglucose, and sucrose intravenously. These sugars were selected because of their prior use for intestinal permeability and mucosal function testing in humans and dogs. Urethral catheterization with a closed collection system was used for collection of cumulative urine samples prior to and 2, 4, 6, 8, 10, 12, and 24 h after administration of the sugar solution. High-pressure anion exchange liquid chromatography with pulsed amperometric detection was used to measure the concentrations of each sugar in the urine and calculate urinary recovery. Twenty-four hour cumulative urinary recovery for each sugar from the cats, was lower than expected compared to dogs and humans. All 5 sugars had the highest percentage of urinary recovery during the first 2 h after administration. Mean sugar elimination rate constants and half-lives ranged from 0.268/h for methylglucose to 0.415/h for lactulose and 1.67 h for lactulose to 2.59 h for methylglucose, respectively. Metabolism and incomplete urine collection are possible reasons for lower cumulative urinary recoveries of these 5 sugars in cats compared with dogs. Although these 5 sugars are not ideal marker molecules, they may still be useful for intestinal permeability and mucosal function testing in cats.     

Responses to water withdrawal of tobacco plants genetically engineered with the AtTPS1 gene: a special reference to photosynthetic parameters

We have previously obtained several lines of tobacco transformed with a trehalose-6-phosphate synthase gene of plant origin (Arabidopsis thaliana), involved in the first step of the biosynthesis of trehalose, a known osmoprotectant. Two showed distinct intensity of expression: high (B5H) and low (B1F). Such lines were analyzed for trehalose-6-phosphate content and the obtained results demonstrated to be in accordance with the expression results. In order to study the responses of photosynthesis to water deficit of transgenic lines in comparison to wild type (WT), three experiments were performed under different conditions: (1) Relative water (2) Leaf gas exchange (3) Modulated Chlorophyll a Fluorescence. Different responses in RWC of plant lines to water withdrawal were detected, with transgenic line B5H indicating less water loss after the water withdrawal period. Similar responses to water deficit regarding the leaf gas exchanges were recorded for the three lines. When subjected to water deficit stress situations, higher F _v/F _m, Φ_PSII and qP were detected for the transgenic lines. Under a SWC of 20% where higher values for such parameters were detected with special relevance for the B5H line, indicating a possible higher ability to withstand severe drought stress and to resist to prolonged periods without water than the B1F and WT lines.