Increase of metallothionein-immunopositive chloride cells in the gills of brown trout and rainbow trout after exposure to sewage treatment plant effluents

Metallothionein, a biomarker of exposure and toxicity of heavy metals, has been detected in the gills of brown trout (Salmo trutta fario L.) and rainbow trout (Oncorhynchus mykiss Richardson) by means of immunohistochemistry. A very prominent labelling of chloride cells was found after exposure to diluted sewage plant effluents. No significant increase was observed in either the number of labelled cells or their labelling intensity after exposure to water of a polluted river compared to fish kept in tap water. These results do not correlate with findings of a histopathological study, suggesting that the metal levels at the sewage treatment plant were too low to produce gross histopathology. A comparison between the species indicated that the rainbow trout showed a generally higher metallothionein expression than the brown trout

A tough egg to crack: recreational boats as vectors for invasive goby eggs and transdisciplinary management approaches

Non-native invasive species are a major threat to biodiversity, especially in freshwater ecosystems. Freshwater ecosystems are naturally rather isolated from one another. Nonetheless, invasive species often spread rapidly across water sheds. This spread is to a large extent realized by human activities that provide vectors. For example, recreational boats can carry invasive species propagules as ‘aquatic hitch-hikers’ within and across water sheds. We used invasive gobies in Switzerland as a case study to test the plausibility that recreational boats can serve as vectors for invasive fish and that fish eggs can serve as propagules. We found that the peak season of boat movements across Switzerland and the goby spawning season overlap temporally. It is thus plausible that goby eggs attached to boats, anchors or gear may be transported across watersheds. In experimental trials we found that goby eggs show resistance to physical removal (90mN attachment strength of individual eggs) and stay attached if exposed to rapid water flow (2.8m s-138 for 1h). When exposing the eggs to air, we found that hatching success remained high (>95%) even after eggs had been out of water for up to 24h. It is thus plausible that eggs survive during pick up, within water and overland transport by boats. We complemented the experimental plausibility tests with a survey on how decision makers from inside and outside academia rate the feasibility of managing recreational boats as vectors. We found consensus that an installation of a preventive boat vector management is considered an effective and urgent measure. This study advances our understanding of the potential of recreational boats to serve as vectors for invasive vertebrate species, and demonstrates that preventive management of recreational boats is considered feasible by relevant decision makers in- and outside academia

Indicators of nutritional status of turbot Scophthalmus maximus (L., 1758) larvae

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Indicators of nutritional status of turbot Scophthalmus maximus (L., 1758) larvae

Se han analizado diferentes indicadores del estado nutricional de larvas de rodaballo Scophthalmus maximus (L., 1758) alimentadas de hasta 53 días de edad y se han comparado con los de otras larvas sometidas a condiciones de inanición. Los indicadores estudiados fueron longitud, peso seco, condición relativa larvaria, diámetro del otolito, histología digestiva de las larvas, contenido en ácidos grasos, ácido ascórbico, RNA, DNA Y proteínas. Los procesos de inanición se llevaron a cabo a los 3, 9, 16, 23 Y 27 días de edad y los análisis de estas larvas fueron comparados con los de larvas alimentadas de las mismas edades. Durante las primeras 24 horas de inanición, las goticulas lipídicas en las células epiteliales desaparecen por completo del intestino. Después, la condición relativa disminuye aproximadamente el 5% por día y el diámetro relativo del otolito se incrementa en el 5% por día. Se producen también disminuciones en el peso seco, el contenido proteico, los niveles de ácidos grasos 18:1Ω-9, 20:5Ω-3 (EPA) y los de otros ácidos grasos altamente insaturados (Ω-3 HUFA), y en la relación RNA/DNA. Sin embargo, la mayoría de los indicadores investigados muestran una alta variación, incluso entre las distintas experiencias de cultivo realizadas, por lo que se concluye que las gotículas de lípidos en las células epiteliales del intestino, la condición relativa y el diámetro relativo del otolito son las únicas variables que pueden ser útiles para detectar un proceso de inanición en larvas de rodaballo.Nutritional status indicators of larvae of turbot Scophthalmus maximus (L., 1758) were investigated in feeding and starving turbot larvae from hatching up to an age of 53 days. The study included the whole-larvae parameters of length, dry weight and relative condition; the organ-related characteristics otolith diameter and intestinal histology; and the biochemical indicators fatty acids, ascorbic acid, RNA, DNA and total protein. Starvation was started at day 3, 9, 16, 23 and 27, and starved larvae were compared with feeding larvae from the same rearing group. After onset of starvation, lipid droplets in the intestinal epithelial cells disappeared within 24 h. Later; the influence of starvation also became apparent in most of the other indicators studied. Relative condition decreased by about 5%/day and relative otolith diameter increased by about 5%/day. A histologically observed total disappearance of chylomicrons and lipid droplets in the intestinal epithelial cells was in accordance with a drop in dry weight, protein content, and the fatty acids 18:1Ω-9, 20:5Ω-3 (EPA) and Ω-3 HUFA (Highly Unsaturated Fatty Acids), as well as the RNA/DNA ratio in starved larvae. However, most of the indicators studied showed such a high variation between individual rearing groups that only the parameters lipid droplets in intestinal epithelial cells, relative condition and relative otolith diameter seem useful for detecting starvation in turbot larvae.Instituto Español de Oceanografí

No evidence of microplastic ingestion in emperor penguin chicks (Aptenodytes forsteri) from the Atka Bay colony (Dronning Maud Land, Antarctica)

Microplastic (500 μm using Attenuated Total Reflection Fourier-transform Infrared (ATR-FTIR) spectroscopy. A total of 85 putative particles, mostly in the shape of fibers (65.9 %), were sorted. However, none of the particles were identified as MP applying state-of-the-art methodology. Sorted fibers were further evidenced to originate from contamination during sample processing and analyses. We find that MP concentrations in the local food web of the Weddell Sea and Dronning Maud Land coastal and marginal sea-ice regions; the feeding grounds to chick-rearing emperor penguin adults, are currently at such low levels that no detectable biomagnification is occurring via trophic transfer. Being in contrast to MP studies on other Antarctic and sub-Antarctic penguin species, our comparative discussion including these studies, highlights the importance for standardized procedures for sampling, sample processing and analyses to obtain comparable results. We further discuss other stomach contents and their potential role for MP detection, as well as providing a baseline for the long-term monitoring of MP in apex predator species from this region

Transient increase in chloride cell number and heat shock protein expression (hsp70) in brown trout (Salmo trutta fario) exposed to sudden temperature elevation

The native cold-adapted brown trout ( Salmo trutta fario ) is often the subject of biomonitoring field studies. Groups of trout were exposed to a sudden temperature rise, from 8 degrees C to 19 degrees C for two hours, and thereafter set back to 8 degrees C. Gill samples of control animals, of fish after the exposure period, and after 24 and 48 hours of recovery at a temperature of 8 degrees C were examined histologically, immunohistochemically, electron microscopically, and by Western blot analysis. By means of immunohistochemistry and electron microscopy, an increase of chloride cells was observed after the temperature elevation . During the recovery period the number of chloride cells decreased. Western blot analysis for stress proteins ( hsp70 ), widely used as a biomarker for environmental stress, was performed from skin and gill. Whereas in the gill both isoforms, the constitutive and the heat inducible form, of hsp70 were detected in all groups, in the skin the control animals only showed the constitutive form. After two hours of exposure both isoforms were visible. An increased expression of hsp70 could be demonstrated in both organs after the exposure. Comparison of the hsp70 values between gill and skin showed tissue-specific differences during the recovery period. In the gill hsp70 rapidly decreased, while in the skin the level remained elevated over the whole observation period. When hsp70 is used as a biomarker in field studies, the fast and organ-specific reaction in the gill and skin of brown trout has to be taken into consideration

A vast icefish breeding colony discovered in the Antarctic

A breeding colony of notothenioid icefish (Neopagetopsis ionah, Nybelin 1947) of globally unprecedented extent has been discovered in the southern Weddell Sea, Antarctica. The colony was estimated to cover at least similar to 240 km(2) of the eastern flank of the Filchner Trough, comprised of fish nests at a density of 0.26 nests per square meter, representing an estimated total of -60 million active nests and associated fish biomass of >60,000 tonnes. The majority of nests were each occupied by 1 adult fish guarding 1,735 eggs (+/- 433 SD). Bottom water temperatures measured across the nesting colony were up to 2 degrees C warmer than the surrounding bottom waters, indicating a spatial correlation between the modified Warm Deep Water (mWDW) upflow onto the Weddell Shelf and the active nesting area. Historical and concurrently collected seal movement data indicate that this concentrated fish biomass may be utilized by predators such as Weddell seals (Leptonychotes weddellii, Lesson 1826). Numerous degraded fish carcasses within and near the nesting colony suggest that, in death as well as life, these fish provide input for local food webs and influence local biogeochemical processing. To our knowledge, the area surveyed harbors the most spatially expansive continuous fish breeding colony discovered to date globally at any depth, as well as an exceptionally high Antarctic seafloor biomass. This discovery provides support for the establishment of a regional marine protected area in the Southern Ocean under the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) umbrella

An early history of T cell-mediated cytotoxicity.

After 60 years of intense fundamental research into T cell-mediated cytotoxicity, we have gained a detailed knowledge of the cells involved, specific recognition mechanisms and post-recognition perforin-granzyme-based and FAS-based molecular mechanisms. What could not be anticipated at the outset was how discovery of the mechanisms regulating the activation and function of cytotoxic T cells would lead to new developments in cancer immunotherapy. Given the profound recent interest in therapeutic manipulation of cytotoxic T cell responses, it is an opportune time to look back on the early history of the field. This Timeline describes how the early findings occurred and eventually led to current therapeutic applications