Temperature record in the oxygen stable isotopes of Pacific sardine otoliths: Experimental vs. wild stocks from the Southern California Bight

Pacific sardines (Sardinops sagax) are commercially fished in Canada, USA, and Mexico along approximately 5000 km of coastal waters that experience a wide range of temperatures. Trinational management of the species can be problematic because the connectivity between spawning, recruitment, stock residency, and migration in some years may not be well predicted. Oxygen isotopic value of otoliths (δ¹⁸O_otolith) has been used to infer stock residency and movement of fish populations within regions, but few studies have used laboratory data to establish a predictive temperature model to validate δ¹⁸O_otolith values of wild fish. We conducted a growth experiment with juveniles at different temperatures using Southern California Bight (SCB) seawater to test the assumption that Pacific sardine otoliths accurately record environmental water temperature in the presence of constant salinity. Sardine δ¹⁸O_otolith values were significantly and negatively correlated with temperature according to the linear model:

δ¹⁸Ootolith(‰)−δ¹⁸Owater(‰)=−0.132(±0.003 SE)×Temperature(°C)+2.455(±0.043 SE)     

Cytokine mRNA expression in Peromyscus yucatanicus (Rodentia: Cricetidae) infected by Leishmania (Leishmania) mexicana

Peromyscus yucatanicus, the main reservoir of Leishmania (Leishmania) mexicana in the Yucatan peninsula of Mexico, reproduces clinical and histological pictures of LCL in human as well as subclinical infection. Thus, we used this rodent as a novel experimental model. In this work, we analyzed cytokine mRNA expression in P. yucatanicus infected with L. (L.) mexicana. Animals were inoculated with either 2.5 × 10⁶ or 1 × 10² promastigotes and cytokine expressions were analyzed by real-time RT-PCR in skin at 4 and 12 weeks post-infection (wpi). Independently of the parasite inoculum none of the infected rodents had clinical signs of LCL at 4 wpi and all expressed high IFN-γ mRNA. All P. yucatanicus inoculated with 2.5 × 10⁶ promastigotes developed signs of LCL at 12 wpi while the mice inoculated with 1 × 10² remained subclinical. At that time, both IFN-γ and IL-10 were expressed in P. yucatanicus with clinical and subclinical infections. Expressions of TNF-α and IL-4 were significantly higher in clinical animals (2.5 × 10⁶) compared with subclinical ones (1 × 10²). High TGF-β expression was observed in P. yucatanicus with clinical signs when compared with healthy animals. Results suggested that the clinical course of L. (L.) mexicana infection in P. yucatanicus was associated with a specific local pattern of cytokine production at 12 wpi.     

Amentoflavone isolated from Selaginella sellowii Hieron induces mitochondrial dysfunction in Leishmania amazonensis promastigotes

Leishmaniasis chemotherapy is a bottleneck in disease treatment. Although available, chemotherapy is limited, toxic, painful, and does not lead to parasite clearance, with parasite resistance also being reported. Therefore, new therapeutic options are being investigated, such as plant-derived anti-parasitic compounds. Amentoflavone is the most common biflavonoid in the Selaginella genus, and its antileishmanial activity has already been described on Leishmania amazonensis intracellular amastigotes but its direct action on the parasite is controversial. In this work we demonstrate that amentoflavone is active on L. amazonensis promastigotes (IC₅₀ = 28.5 ± 2.0 μM) and amastigotes. Transmission electron microscopy of amentoflavone-treated promastigotes showed myelin-like figures, autophagosomes as well as enlarged mitochondria. Treated parasites also presented multiple lipid droplets and altered basal body organization. Similarly, intracellular amastigotes presented swollen mitochondria, membrane fragments in the lumen of the flagellar pocket as well as autophagic vacuoles. Flow cytometric analysis after TMRE staining showed that amentoflavone strongly decreased mitochondrial membrane potential. In silico analysis shows that amentoflavone physic-chemical, drug-likeness and bioavailability characteristics suggest it might be suitable for oral administration. We concluded that amentoflavone presents a direct effect on L. amazonensis parasites, causing mitochondrial dysfunction and parasite killing. Therefore, all results point for the potential of amentoflavone as a promising candidate for conducting advanced studies for the development of drugs against leishmaniasis.     

Effect of maternal fat reserves on the fatty acid composition of sardine (Sardina pilchardus) oocytes

We compared the fatty acid (FA) composition of the muscle and gonads of female Iberian sardines with hydrated oocytes collected during the 2002/03 spawning season off southern Portugal (November and February) and off western Portugal (February). Sardine condition and total FA concentration in the muscle decreased between the two sampling dates, while the gonadosomatic index was similar between samples. Total monounsaturated FA concentrations in sardine gonads were different for the three samples while saturated and polyunsaturated FA concentrations were similar. Significant linear relations were found between FA concentrations in female muscle and oocytes, including eicosapentaenoic acid (EPA; 20:5n − 3) and arachidonic acid (AA; 20:4n − 6), both being essential for normal larval development. The concentration of docosahexaenoic acid (DHA; 22:6n − 3) in oocytes was independent on muscle concentration, probably resulting from its selective transfer to the oocytes. The EPA/DHA ratio was highly conserved in sardine tissues, while DHA/AA and EPA/AA ratios varied significantly between samples. These results indicate that the FA content of eggs produced by sardines varies throughout the spawning season, egg FA concentrations decreasing as females lose condition, and FA composition also shows spatial variability. Both types of variability may have a significant impact on egg quality, particularly on the amount of reserves available to larvae affecting their resistance to starvation, and the appropriate FA composition required for normal growth.     

Capillaria plica (syn. Pearsonema plica) infection in a dog with chronic pollakiuria: Challenges in the diagnosis and treatment

Capillaria plica (syn. Pearsonema plica) is a nematode parasite of the urinary tract of canids, felids and mustelids, which can cause cystitis, pollakiuria, dysuria and hematuria. An eight-month-old female crossbred dog from Switzerland presented a six-month history of frequent urination. During the first clinical examination, C. plica eggs were detected in the urine sediment. Three series of treatments with fenbendazole (50 mg/kg body weight [BW]/day, orally) for 10 days each, three single day treatments with moxidectin–imidacloprid (spot-on) and one single administration of ivermectin (0.2 mg/kg BW subcutaneously) were performed within an eight-month period. None of those treatments succeeded in eliminating the C. plica infection or in resolving the clinical signs. An endoscopic examination of the urine bladder still revealed numerous adult viable C. plica worms attached to the bladder mucosa. A two-day treatment with levamisole (7.5 mg/kg BW/day intramuscularly) was subsequently performed. An endoscopic control of the urine bladder two days after this treatment and a urine analysis after two weeks confirmed the elimination of the parasites. The clinical signs disappeared within one month. Levamisole was shown to be effective against C. plica infection in a dog, whereas previous treatments with fenbendazole, moxidectin and ivermectin had failed.     

Mitochondrial DNA Sequence Variation Suggests the Lack of Genetic Heterogeneity in the Adriatic and Ionian Stocks of Sardina pilchardus

A genetic stock structure analysis of 11 sardine samples from the Adriatic Sea and Ionian neighboring area was carried out through sequence variation analysis of a 307-bp cytochrome b gene fragment in order to identify self-recruiting units in the Adriatic Sardina pilchardus stock. The overall lack of genetic subdivision among samples detected by analysis of molecular variance, pairwise Φ_st values, and the exact test of population differentiation indicates this sardine stock is part of a larger self-recruiting population whose boundaries are larger than the investigated area. This conclusion is in agreement with preliminary allozymic and mitochondrial DNA restriction fragment length polymorphism data, but contradicts the previous identification of 2 subpopulations of sardines in the Adriatic Sea argued on morphologic differences, which could be rather attributed to different hydrographic or ecologic conditions occurring in different areas of the Adriatic Sea. The reduced gene flow observed between Adriatic-Ionian and Spanish sardine geographic samples (P < 0.001) suggests that reproductively isolated populations of sardines may occur in the Mediterranean Sea.     

Microbial sulfate reduction at low (8 °C) temperature using waste sludge as a carbon and seed source

Biological treatment of sulfate and metal-containing wastewater (such as acid mine drainage) is a viable option due to lower cost and better sludge quality compared to conventional chemical treatment. Although several substrates can be used as carbon source, a low-cost substrate is required for large scale applications. This study was conducted to investigate the suitability of waste sludge as a carbon and seed source for sulfate reduction at 8 °C in batch bioassays. Around 7 mmol of sulfate was reduced when the waste sludge mixture (WS) (6700 mg SS l^?1) from primary and secondary settling tank was supplemented as a carbon and seed source. However, only 1.6 mmol of sulfate was reduced with anaerobic digester effluent (ADS) (5300 mg SS l^?1). The produced H₂S from 1 g VSS l^?1 WS and ADS oxidation can theoretically precipitate around 90 and 35 mg Fe²⁺, respectively. Both WS and ADS oxidized ethanol to acetate at similar rates. It appears that WS is a good candidate for carbon and start-up seed source of sulfate reduction at 8 °C, whereas sulfidogenic acetate oxidation was the limiting step. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes showed that both sludge sources contain Desulfomicrobium apsheronum strain.     

Haemonchus contortus: A multiple-resistant Brazilian isolate and the costs for its characterization and maintenance for research use

The aim of this work was to determine the resistance level of Haemonchus contortus isolated from the Santa Inês flock of the Embrapa (Brazilian government's Agricultural Research Company), Southeast Livestock Unit (CPPSE), as well as to determine costs of characterizing and maintaining this isolate in host donors. Forty-two male Santa Inês lambs were experimentally infected with 4000 H. contortus infective larvae of the field isolate of CPPSE, called Embrapa2010, and divided into six treatment groups, which received triclorfon, albendazol plus cobalt sulfate, ivermectin, moxidectin, closantel and levamisole phosphate, as well as a negative control group (water). Egg per gram (EPG) counts were performed at 0, 3, 7, 10 and 14 days post treatment when the animals were slaughtered for parasite count. The data were analyzed using the RESO statistical program, considering anthelmintic resistance under 95% of efficacy. EPG and worm count presented a linear and significant relation with 94% determination coefficient. The susceptibility results obtained by RESO through both criteria (EPG and worm count) were equal, except for closantel, showing that the isolate Embrapa2010 is resistant to benzimidazoles, macrocyclic lactones and imidazothiazoles. The need of a control group did not appear to be essential since the result for susceptibility in the analyses with or without this group was the same. Suppression in egg production after treatment did not occur in the ivermectin and moxidectin groups. In the control group, the establishment percentage was just 12.5 because of the low number of third-stage larvae, resistance (innate and infection immunity) of the animals studied plus good nutrition. Drug classes presented similar efficacy between adults and immature stages. The costs for isolate characterization were calculated for 42 animals during 60 days. The total cost based on local market rates was approximately US$ 8000. The precise identification of Brazilian isolates and their establishment in host donors would be useful for laboratorial anthelmintic resistance diagnoses through in vitro tests, which has an annual cost of approximately US$ 2500 for maintenance in host donors.     

The effect of the biflavonoid 2″,3″-dihydroochnaflavone on Trypanosoma cruzi Y strain

Trypanosoma cruzi is the causative agent of Chagas disease which affects 8 million people in Latin America. The parasite possesses high capacity to evade host immune system and the available drugs to treat Chagas disease present low efficacy combined to serious side effects to patients. Therefore, the identification of alternative therapeutics is essential. Brazilian flora exhibits an immense diversity of metabolites with great potential to be developed into new drugs. We investigated the action of 2″,3″-dihydroochnaflavone a biflavonoid extracted from Luxemburgia nobilis Eichler ex Engl. (Ochnaceae) against T. cruzi (Y strain). Our experiments showed that this compound is effective against parasite epimastigote forms, presenting IC₅₀ value of (2.5 ± 0.1) μM after 96 h of treatment. Ultrastructure alterations were also detected in treated epimastigotes especially mitochondrial enlargement at the kinetoplast region. At the concentration of 30 μM, the compound killed (61.6 ± 3.37)% of the parasite in its amastigote form. In addition, at the same concentration, the compound killed all trypamastigotes growing within murine macrophages after 7–9 days of infection. Nonetheless, the biflavonoid concentrations were harmless to murine enriched population of lymphocytes and peritoneal macrophages. These results indicate that 2″,3″- dihydroochnaflavone presents activity against T. cruzi.     

Thermal behavior of the Pacific sardine (Sardinops sagax) acclimated to different thermal cycles

The study of thermal behavior of fishes provides useful data to enable predictions of the effect of climatic change on populations so as to ensure good management of fisheries. The Pacific sardine has a complex population dynamics; three subpopulation have been proposed (cold, temperate and warm).We exposed Sardinops sagax caeruleus (temperate sub-population) to two different thermal cycles, which were chosen to be consistent with the temperatures reported in two distant places Cedros Island (CIc: 18–23 °C) and San Pedro (SPc: 13–18 °C).The thermal behavior of the SPc and CIc sardines was affected by acclimation treatment: the interval of thermal preference was 17.1–19.9 and 16.0–18.8 °C, while the lethal temperatures interval (LT50) was 7.7–25.6 and 6.9–24.3 °C, and the critical limits CTMax and CTMin were 7.1–32.2 and 5.5–30.4 °C, respectively.The results of thermal behavior showed that sardines of the temperate subpopulation are more tolerant to cold; this might suggest that they would be more able to survive in California and Oregon than in Baja California Sur and the Gulf of California.     

Effect of dietary copper on the growth performance,non-specific immunity and resistance to Aeromonas hydrophila of juvenile Chinese mitten crab,Eriocheir sinensis

An 8-week feeding trial was conducted to determine the dietary copper (Cu) on growth performance and immune responses of juvenile Chinese mitten crab Eriocheir sinensis. Six semi-purified diets with six copper levels (1.88, 11.85, 20.78, 40.34, 79.56 and 381.2 mg kg^?1 diet) of CuSO₄·5H₂O were fed to E. sinensis (0.45 ± 0.01 g). Each diet was fed to the crab in five replicates. The crab fed diets with 20.78 and 40.34 mg Cu kg^?1 diet had significantly greater weight gain and hemolymph oxyhemocyanin content than those fed diets with 1.88 and 381.2 mg Cu kg^?1 diet. Survival rates of crab were not significantly different between all treatment groups. The activities of copper–zinc superoxide dismutase (Cu–Zn SOD), phenoloxidase (PO), and total hemocyte count (THC) significantly increased when the supplementation of dietary copper reached 20.78–40.34 mg Cu kg^?1 diets. In the bacteria challenge experiment with Aeromonas hydrophila, survival rates significantly increased and reached a plateau when the dietary copper increased from 1.88 to 40.34 mg kg^?1, whereas significantly decreased when the dietary copper increased from 40.34 to 381.2 mg kg^?1. This study indicates that the level of dietary copper is important in regulating growth and immune response in crab.     

Microbial processes and bacterial populations associated to anaerobic treatment of sulfate-rich wastewater

A pilot-scale (1.2 m³) anaerobic sequencing batch biofilm reactor (ASBBR) containing mineral coal for biomass attachment was fed with sulfate-rich wastewater at increasing sulfate concentrations. Ethanol was used as the main organic source. Tested COD/sulfate ratios were of 1.8 and 1.5 for sulfate loading rates of 0.65–1.90 kgSO₄²⁻/cycle (48 h-cycle) or of 1.0 in the trial with 3.0 gSO₄²⁻ l⁻¹. Sulfate removal efficiencies observed in all trials were as high as 99%. Molecular inventories indicated a shift on the microbial composition and a decrease on species diversity with the increase of sulfate concentration. Beta-proteobacteria species affiliated with Aminomonas spp. and Thermanaerovibrio spp. predominated at 1.0 gSO₄²⁻ l⁻¹. At higher sulfate concentrations the predominant bacterial group was Delta-proteobacteria mainly Desulfovibrio spp. and Desulfomicrobium spp. at 2.0 gSO₄²⁻ l⁻¹, whereas Desulfurella spp. and Coprothermobacter spp. predominated at 3.0 gSO₄²⁻ l⁻¹. These organisms have been commonly associated with sulfate reduction producing acetate, sulfide and sulfur. Methanogenic archaea (Methanosaeta spp.) was found at 1.0 and 2.0 gSO₄²⁻ l⁻¹. Additionally, a simplified mathematical model was used to infer on metabolic pathways of the biomass involved in sulfate reduction.     

Canine cognitive dysfunction syndrome: Prevalence,clinical signs and treatment with a neuroprotective nutraceutical

Cognitive dysfunction syndrome (CDS) is a progressive neurodegenerative disorder of senior dogs. Since age-related behavioural changes may be useful indicators for early diagnosis and treatment, the first purpose of the present study was to investigate the prevalence of clinical signs of CDS in a general population of aged dogs. The second aim was to evaluate the use of a neuroprotective nutraceutical (Senilife^®, Innovet Italia srl, Rubano, Italy) using an open-label clinical pilot trial.Dogs were recruited from a geriatric population not referred for behavioural consultations. A questionnaire with a checklist of behaviours was filled out to evaluate behavioural items grouped in the following categories: disorientation (D), socio-environmental interaction (I), sleep–wake cycles (S), house soiling (H), general activity (A)—(DISHA). Each owner was asked to rate the frequency of the behavioural signs: never, rarely, often, or always.One hundred and twenty-four dogs were assessed in the first survey; 22 of the 124 dogs tested in the survey were ruled out based on exclusion criteria (clinically and/or sensory severe impairment), 42 dogs had alterations in one category and 33 dogs had signs in 2 or more categories. Consequently 75 dogs had signs consistent with CDS.Among this population eight dogs affected by CDS were enrolled for the second step of the project, an open-label clinical pilot trial with the neuroprotective nutraceutical Senilife^®. Senilife^® contains 25 mg phosphatidylserine, 50 mg of standardized Ginkgo biloba extract, 33.5 mg/d-alpha tocopherol and 20.5 mg pyridoxine per capsule and is dosed at one capsule per 5 kg body weight. The investigator asked the owners to rate the frequency of behaviours referring to DISHA using a four point frequency scale (never, rarely, often, always). Post-treatment, the owners were asked to evaluate all the signs in each category on a five point scale (much better, slightly better, the same, slightly worse, much worse). At the time of the first visit (V₀) the owners were briefed verbally about the procedure; no behavioural advice was given throughout the study time and whenever appropriate therapy with Senilife^® (was started. At V₀, V₁ (28 ± 3 days), V₂ (56 ± 3 days) and V₃ (84 ± 3 days) a control visit was performed and the owners were interviewed. Dogs treated with Senilife^® showed a highly significant difference at V₃ compared to V₀ (p < 0.001).Preliminary results from dogs on Senilife^® showed a marked improvement of CDS related signs, even if the dogs failed to show a complete remission of symptoms.     

Changes in intestinal morphology and microbiota caused by dietary administration of inulin and Bacillus subtilis in gilthead sea bream (Sparus aurata L.) specimens

Changes produced in gilthead sea bream (Sparus aurata L.) intestinal morphology and microbiota caused by dietary administration of inulin and Bacillus subtilis have been studied. Gilthead sea bream specimens were fed diets containing 0 (control), inulin (10 g kg^?1), B. subtilis (10⁷ cfu g^?1), or B. subtilis + inulin (10⁷ cfu g^?1 + 10 g kg^?1) for four weeks. Curiously, fish fed the experimental diets (inulin, B. subtilis, or B. subtilis + inulin) showed the same morphological alterations when studied by light and electron microscopy, while significant differences in the signs of intestinal damage were detected by the morphometric study. All of the observed alterations were present only in the gut mucosa, and intestinal morphometric study revealed no effect of inulin or B. subtilis on the intestinal absorptive area. Furthermore, experimental diets cause important alterations in the intestinal microbiota by significantly decreasing bacterial diversity, as demonstrated by the specific richness, Shannon, and range-weighted richness indices. The observed alterations demonstrate that fish fed experimental diets had different signs of gut oedema and inflammation that could compromise their body homeostasis, which is mainly maintained by the epithelial lining of the gastrointestinal tract. To our knowledge, this is the first in vivo study regarding the implications of the use of synbiotics (conjunction of probiotics and prebiotics) on fish gut morphology and microbiota.     

Description of a new species of myxobolid parasite,Henneguya pindaibensis n. sp. (Cnidaria: Myxosporea), infecting the gills of Boulengerella cuvieri (Spix and Agassiz, 1829) from Brazil

Myxozoans are microscopic cnidarians that mainly parasitize fishes. The present study aimed to describe a new myxozoan parasite from the gills of Boulengerella cuvieri (Spix and Agassiz, 1829) by morphological and molecular analysis. The fish was collected in 2019 at the Pindaíba River, municipality of Cocalinho, Mato Grosso State, Brazil. Whitish and circular plasmodia were found in the primary gill filaments, occupying an intralamellar position, with an average of 0.5 mm in diameter. Henneguya Thélohan, 1892 myxospores found inside the plasmodia were elongated and ellipsoidal, consisting of two long and elliptical shell valves with two long, tapering caudal appendages. Morphometric measurements revealed a total spore length of 36.1 ± 2.0 μm; spore body length of 12.8 ± 0.5 μm; spore width of 4.9 ± 0.3 μm; tail length of 23.3 ± 1.6 μm; capsule length of 7.2 ± 0.4 μm; capsule width of 1.5 ± 0.2 μm; and 10 coils in the polar filament. Phylogenetic analysis showed that the isolates from this study were grouped into the main-clade of freshwater fishes, within a group of species parasitizing fishes from Brazil. Intergenotypic difference ranged from 23%–25.9% compared with other Brazilian myxozoan isolates. Using molecular and morphological characterization, this parasite was identified as a new species of the genus Henneguya.     

Glucocorticoid receptors on and in a unicellular organism,Cryptobia salmositica

This is the first report to our knowledge that demonstrates a functional steroid hormone receptor in a protozoon. The study used Cryptobia salmositica, a pathogenic haemoflagellate found in salmonid fishes. It has been previously shown that cortisol and dexamethasone (a synthetic glucocorticoid) enhanced the multiplication of C. salmositica under in vitro conditions indicating the presence of glucocorticoid receptors on/in the parasite. Also, the glucocorticoid receptor antagonist, mifepristone (RU486), inhibited the stimulatory effect of the two glucocorticoids on parasite multiplication. In the present study, we used an antibody (produced in a rabbit against glucocorticoid receptor protein) agglutination test and confocal microscopy with immunohistofluorescence staining to demonstrate cortisol-glucocorticoid receptor-like protein receptors on the plasma membrane and in the cytoplasm of the parasite. In two in vitro studies, the addition of 50 ng ml⁻¹ of RU486 was more effective in inhibiting parasite replication in cultures with 7,000 parasites ml⁻¹ than in cultures with 14,000 parasites ml⁻¹. Also, 100 ng ml⁻¹ of RU486/ml was more effective than 50 ng ml⁻¹ in inhibiting parasite multiplication in the 14,000 parasites ml^-1 cultures. These in vitro studies indicate that the number of binding sites on/in the parasite is finite. The findings may be important in future studies especially on steroid receptor signalling pathways and dissection of ligand–receptor interactions, and for evaluating the adaptations that develop in pathogens as part of the host–parasite interaction.     

Copper biosorption on Lyngbya putealis: Application of response surface methodology (RSM)

The potential use of biosorbent prepared from an indigenously isolated cyanobacterium, Lyngbya putealis, for the removal of copper from aqueous solution has been investigated under optimized conditions in this study. Batch mode experiments were performed to determine the adsorption equilibrium and kinetic behavior of copper in aqueous solution allowing the computation of kinetic parameters and maximum metal adsorption capacity. Influences of other parameters like initial metal ion concentration (10-100 mg l⁻¹), pH (2-8) and biosorbent dose (0.1-1.0 g/100 ml) on copper adsorption were also examined, using Box-Behnken design matrix. Very high regression coefficient between the variables and the response (R² = 0.9533) indicates excellent evaluation of experimental data by second order polynomial regression model. The response surface method indicated that 40-50 mg l⁻¹ initial copper concentration, 6.0-6.5 pH and biosorbent dose of 0.6-0.8 g/100 ml were optimal for biosorption of copper by biosorbent prepared from L. putealis. On the basis of experimental results and model parameters, it can be inferred that the biosorbent which has quite high biosorption capacity can be utilized for the removal of copper from aqueous solution.     

Characterization of paralytic shellfish toxins in seawater and sardines (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) during blooms of <Emphasis Type="Italic">Gymnodinium catenatum</Emphasis>

The re-emergence of Gymnodinum catenatum blooms after a 10 year hiatus of absence initiated the present investigation. This study aims to evaluate the exposure of small pelagic fishes to paralytic shellfish toxins (PST) during blooms of G. catenatum. Sardines (Sardina pilchardus) were selected as a representative fish species. In order to assess toxin availability to fish, both intracellular PSTs (toxin retained within the algal cells) and extracellular PSTs (toxin found in seawater outside algal cells) were quantified, as well as toxin levels within three fish tissue matrices (viscera, muscle and brain). During the study period, the highest cell densities of G. catenatum reached 2.5 × 10⁴ cells l⁻¹ and intracellular PST levels ranged from 3.4 to 398 ng STXeq l⁻¹ as detected via an enzyme linked immunosorbent assay (ELISA). Measurable extracellular PSTs were also detected in seawater (0.2–1.1 μg STXeq l⁻¹) for the first time in Atlantic waters. The PST profile in G. catenatum was determined via high performance liquid chromatography with fluorescence detection (HPLC-FLD) and consisted mostly of sulfocarbamoyl (C1+2, B1) and decarbamoyl (dcSTX, dcGTX2+3, dcNEO) toxins. The observed profile was similar to that reported previously in G. catenatum blooms in this region before the 10-year hiatus. Sardines, planktivorous fish that ingest a large number of phytoplankton cells, were found to contain PSTs in the viscera, reaching a maximum of 531 μg STXeq kg⁻¹. PSTs were not detected in corresponding muscle or brain tissues. The PST profile characterized in sardine samples consisted of the same sulfocarbamoyl and decarbamoyl toxins found in the algal prey with minor differences in relative abundance of each toxin. Overall, the data suggest that significant biotransformation of PSTs does not occur in sardines. Therefore, planktivorous fish may be a good tracer for the occurrence of offshore G. catenatum blooms and the associated PSTs produced by these algae.     

Sulfate reduction and microbial community of autotrophic biocathode in response to acidity

Microbial electrolysis cells (MECs) with autotrophic biocathode are a promising technology for removal of pollutants in wastewater. The aim of this study was to investigate the effect of initial acidity of wastewater on performance of sulfate-reducing biocathodes. MECs with biocathodes were operated with initial pH values of catholyte ranged from 3.0 to 7.0. The optimum initial pH value was 6.0 with a maximum sulfate reductive rate and biomass of 57 mg L⁻¹ d⁻¹ and 2.1 ± 0.4 mg g⁻¹, respectively. With initial pH 7.0, the pH value of catholyte increased to 9.8 ± 0.2 after an operation cycle, which resulted in low performance of the biocathode. A considerable sulfate reductive rate of 31 ± 0.85 mg L⁻¹ d⁻¹ was achieved with initial pH 3.0. Desulfovibrio sp. grew dominantly with abundance of 46%–66% in the cathode biofilm with initial pH values from 3.0 to 6.0 and contributed to the sulfate reduction. Clostridium and Parapedobacter also had high abundance in pH 6.0 cathode, indicated that interspecies electron transfer between electrochemical active and sulfate-reducing bacteria could play an important role in sulfate removal. The results suggest that acidity of catholyte is an important factor to be considered to utilize autotrophic biocathode MECs for wastewater treatment.     

In vivo antimicrobial evaluation of an alanine-rich peptide derived from Pleuronectes americanus

In several organisms, the first barrier against microbial infections consists of antimicrobial peptides (AMPs) which are molecules that act as components of the innate immune system. Recent studies have demonstrated that AMPs can perform various functions in different tissues or physiological conditions. In this view, this study was carried out in order to evaluate the multifunctional activity in vivo of an alanine-rich peptide, known as Pa-MAP, derived from the polar fish Pleuronectes americanus. Pa-MAP was evaluated in intraperitoneally infected mice with a sub-lethal concentration of Escherichia coli at standard concentrations of 1 and 5 mg kg⁻¹. At both concentrations, Pa-MAPs exhibited an ability to prevent E. coli infection and increase mice survival, similar to the result observed in mice treated with ampicillin at 2 mg kg⁻¹. In addition, mice were monitored for weight loss. The results showed that mice treated with Pa-MAPs at 1 mg kg⁻¹ gained 0.8% of body weight during the 72 h of experiment. The same was observed with Pa-MAP at 5 mg kg⁻¹, which had a gain of 0.5% in body weight during the treatment. Mice treated with ampicillin at 2 mg kg⁻¹ show a significant weight loss of 5.6% of body weight. The untreated group exhibited a 5.5% loss of body weight. The immunomodulatory effects were also evaluated by the quantification of IL-10, IL-12, TNF-α, IFN-γ and nitric oxide cytokines in serum, but no immunomodulatory activity was observed. Data presented here suggest that Pa-MAP should be used as a novel antibiotic against infection control.