Antarctic Marine Biology
Assemblages of micronektonic fishes and invertebrates in a gradient of regional warming along the Western Antarctic Peninsula
Autori: Parker ML, Fraser WR, Ashford, J, Patarnello T, Zane L, Torres JJ
Riferimenti: JOURNAL OF MARINE SYSTEMS, vol. 152: 18-41, 2015. DOI: 10.1016/j.jmarsys.2015.07.005
Summary: Micronektonic fishes and invertebrates were sampled with 32 midwater trawls at nine sites along the Western Antarctic Peninsula (WAP) in the austral fall (March–April) of 2010. Study sites were located within four hypothesized hydrographic regions: near Joinville Island in Region I, at Croker Passage, near Anvers Island, and near Renaud Island in Region II, within Marguerite Bay and the Marguerite Trough in Region III, and near Charcot Island in Region IV. A total of 62 taxa representing 12 taxonomic groups of pelagic invertebrates and 9 families of fish were captured, but assemblages were dominated by only a few species. The most numerically abundant taxa were the euphausiids, Thysanoessa macrura, Euphausia superba, and E. crystallorophias, combining to contribute nearly 79% of the total catch. Biomass dominants included E. superba, which contributed more than 44% of the total catch, the notothenioid Pleuragramma antarctica, and the salp, Salpa thompsoni. A comparison of total catches among sites revealed that the largest volumetric abundances and biomasses were captured at the Marguerite Bay site.
Cluster analysis of abundance data identified distinct multispecies assemblages at Joinville Island in Region I, Croker Passage in Region II, Marguerite Bay in Region III, and Charcot Island in Region IV. A fifth distinct assemblage included samples from sites near Anvers and Renaud Island in Region II, and from the Marguerite Trough in Region III. Assemblages at Joinville Island and Croker Passage were both dominated by E. superba and S. thompsoni, but hydrographic conditions at Joinville Island favored a neritic assemblage, underscored by substantial numbers of P. antarctica. The assemblage at Croker Passage was more oceanic in nature with major inputs from the myctophid, Electrona antarctica and the hyperiid amphipod, Themisto gaudichaudii. Marguerite Bay and Charcot Island were well-mixed assemblages with strong representation by both neritic and oceanic fauna. The mid-peninsula assemblage was oceanic in character, being overwhelmingly dominated by Thysanoessa macrura and T. gaudichaudii.
Pleuragramma antarctica were captured at five sites: Joinville Island, Croker Passage, Marguerite Bay, and the two sites near Charcot Island. They were completely absent at the two sites near Anvers Island, at Renaud Island, and in the Marguerite Trough. One fish was captured in Croker Passage. The majority of fish captured in Marguerite Bay were larger than 150 mm standard length (SL), with very few fish of smaller size present. If resident populations of Pleuragramma reproduce and recruit locally rather than being sustained by larval advection, those populations will be highly susceptible to local disappearance. This may be the causative factor behind the absence of Pleuragramma from the mid-peninsula region. Continued warming and subsequent sea ice reductions may not only cause Pleuragramma population collapses in the Marguerite Bay and Charcot Island regions, but may also change the character of the faunal assemblages along the WAP to those of an oceanic system. Previous article in issue
Link: https://www.sciencedirect.com/science/article/pii/S0924796315001207
Characterization and expression of a new cytoplasmic glutathione peroxidase 1 gene in the Antarctic fish Trematomus bernacchii
Autori: Sattin, G.; Bakiu, R.; Tolomeo, A. M.; et al. Sattin G, Bakiu R, Tolomeo AM, Carraro A, Coppola D, Ferro D, Patarnello T, Santovito G
Riferimenti: HYDROBIOLOGIA Volume: 761 Issue: 1 Pages: 363-372, 2015
Summary: Glutathione peroxidases are a family of antioxidant enzymes catalyzing the reduction of H2O2 or organic hydroperoxides. In the present study, we report the molecular characterization and gene expression analysis of a new GPx-1 from the Antarctic fish Trematomus bernacchii. To expand our knowledge on the GPx-1 s evolution within the group of Antarctic fish, in this work, we also presented the cDNA sequencing of this enzyme in other three species, belonging to two families—Nototheniidae (Trematomus eulepidotus, T. lepidorhinus) and Bathydraconidae (Cygnodraco mawsoni). The deduced amino acid sequences were compared with GPx-1 s of other vertebrates by multiple alignment, in order to evaluate the conservation of amino acids involved in the enzyme activity. The results of phylogenetic analyses indicated that fish GPx-1 s possibly originated from independent duplication events, and Antarctic GPx-1 s evolved according to the molecular and morphological phylogeny of Antarctic fish. Basal GPx-1 mRNA expression analyses in various tissues of T. bernacchii specimens indicated that liver and heart displayed the highest mRNA accumulation; probably a protection of these organs against lipid peroxidation is needed.
Link: https://link.springer.com/article/10.1007/s10750-015-2488-6
Genetic differentiation in the ice-dependent fish Pleuragramma antarctica along the Antarctic Peninsula
Autori: Agostini C, Patarnello T, Ashford JR, Torres JJ, Zane L, Papetti C
Riferimenti: JOURNAL OF BIOGEOGRAPHY Vol 42 , 6 :1103-1113.DOI: 10.1111/jbi.12497. JUN 2015
Summary: Pleuragramma antarctica is an Antarctic notothenioid fish with a pelagic life‐cycle. It plays a major trophic role in coastal Antarctic waters as a predator of krill and as prey for penguins and seals. A previous study, using mtDNA to investigate Pleuragramma population structure at multiple Antarctic sites was unable to discriminate between hypotheses of panmixia, with occasional fluctuations of allelic frequencies, and population structure. The aim of the present study was to investigate the population structure of P. antarctica along the Antarctic Peninsula (AP) shelf by microsatellite genotyping.
Evolution of the complement system C3 gene in Antarctic teleosts
Autori: Melillo, D, Varriale, S, Giacomelli, S., Natale, L., Bargelloni, L., Oreste, U., Pinto, M.R., Coscia, M.R.
Riferimenti: Molecular ImmunologyVolume 66, Issue 2, August 01, 2015, Pages 299-309
Summary: Notothenioidei are typical Antarctic teleosts evolved to adapt to the very low temperatures of the Antarctic seas. Aim of the present paper is to investigate sequence and structure of C3, the third component of the complement system of the notothenioid Trematomus bernacchii and Chionodraco hamatus. We determined the complete nucleotide sequence of two C3 isoforms of T. bernacchii and a single C3 isoform of C. hamatus. These sequences were aligned against other homologous teleost sequences to check for the presence of diversifying selection. Evidence for positive selection was observed in the evolutionary lineage of Antarctic teleost C3 sequences, especially in that of C. hamatus, the most recently diverged species. Adaptive selection affected numerous amino acid positions including three residues located in the anaphylatoxin domain. In an attempt to evaluate the link between sequence variants and specific structural features, we constructed molecular models of Antarctic teleost C3s, of their proteolytic fragments C3b and C3a, and of the corresponding molecules of the phylogenetically related temperate species Epinephelus coioides, using human crystallographic structures as templates. Subsequently, we compared dynamic features of these models by molecular dynamics simulations and found that the Antarctic C3s models show higher flexibility, which likely allows for more pronounced movements of both the TED domain in C3b and the carboxyl-terminal region of C3a. As such dynamic features are associated to positively selected sites, it appears that Antarctic teleost C3 molecules positively evolved toward an increased flexibility, to cope with low kinetic energy levels of the Antarctic marine environment.
Link: https://www.sciencedirect.com/science/article/pii/S016158901500351X?via%3Dihub
Effects of dietary soy isoflavones on estrogenic activity, cortisol level, health and growth in rainbow trout, Oncorhynchus mykiss
Autori: Pastore MR, Negrato E, Poltronieri C, Barion G, Messina M, Tulli F, Ballarin C, Maccatrozzo L, Radaelli G, Bertotto D
Riferimenti: Aquaculture Research (2018) 49:1469–1479
Summary: Soy isoflavones (the phytoestrogens genistein, daidzein and glycitein) may act asestrogen receptor agonists or antagonists. The aim of this study was to examine theeffect of dietary isoflavones on growth, reproduction and health in rainbow trout(Oncorhynchus mykiss). Rainbow trout fed three experimental diets containing differ-ent concentrations of isoflavones (0, 500 and 1,500 ppm). Growth, estrogenic activ-ity, plasma estradiol levels, gonadal development, state of stress and histologicalchanges in selected tissues were evaluated at the end of 70 days. Neither growthperformance nor the relative mRNA levels of Insulin Growth Factor I (igf-I) in theliver were influenced by different levels of dietary isoflavones. Plasma and livervitellogenin (VTG) protein levels and plasma 17-b-estradiol (E2) were unaffected bytreatments, although the correlation between plasma levels of E2and VTG densito-metry values was significant (p<.05). The fish gonadosomatic index (GSI) did notsignificantly differ among the three experimental groups but correlated with plasmaVTG densitometry values (p<.05). Plasma, muscle and fin cortisol concentrationsfell within the normal welfare range and were not correlated with isoflavone levels.Histologically, the distal intestine showed a normal morphology with well-differen-tiated enterocytes and in the liver hepatocytes were also normal. A supranuclearaccumulation of lipid droplets in enterocytes and some lipid droplets in hepatocyteswere observed in all tested groups, suggesting an impact of basal dietary lipid ontransport/metabolism of fat in the fish. Overall, the present results suggest that thedoses of isoflavones tested do not compromise rainbow trout reproduction, growthand health.
Link: https://onlinelibrary.wiley.com/doi/epdf/10.1111/are.13602
Histological and micro-/macro-morphological evaluation of intestine in sharpsnout seabream (Diplodus puntazzo) fed soybean meal-based diets added with MOS and inulin as prebiotics
Autori: FERRARA E, GUSTINELLI A, FIORAVANTI ML, RESTUCCI B, QUAGLIO F, MARONO S, PICCOLO G
Riferimenti: Aquaculture International (2015) 23 (6): 1525-1537
Summary: The effects of mannanoligosaccharides (MOS) and inulin (INU) inclusion (8 g kg−1) in a soybean meal (SBM)-containing diet on histology, macro- and micromorphology of proximal and distal intestine of sharpsnout seabream (Diplodus puntazzo) were evaluated. 144 sharpsnout seabream (100 g average initial body weight) were fed with 4 isolipidic and isoproteic diets. At the end of the experimental period (114 days), four fish per diet were randomly sampled. The partial substitution of fish meal (FM) with SBM affected the intestine histology and macromorphology of sharpsnout seabream and modified the enterocyte parameters. The addition of prebiotics has not produced positive effects, leading in some cases to a worsening, especially for INU diet that markedly altered the intestine histology. The micromorphological values were in both proximal and distal intestines significantly affected by the diet: in proximal tract, the nucleus was closer to the apex of the enterocyte in soy-fed fish (SBM, IMU, MOS diets), while fish fed with MOS diet showed the lowest value of enterocyte height, significantly different from the FM diet. In distal tract of intestine, fish fed with FM diet showed the highest value for all considered parameters, while MOS diet resulted in the lowest enterocyte height and supranucleus height among the four diets. SBM-containing diets (SBM, IMU, MOS) resulted in lower values than FM diet for the features of enterocyte nucleus. Microvilli height was not affected by the diet in both proximal and distal tracts. In conclusion in this study, the partial substitution of FM with SBM (40 % on protein basis) induced inflammatory reaction of the gut in sharpsnout seabream, evidenced by histological analysis and changes in morphometric characters of villi and enterocytes, not amended by the addition of MOS and even worsened in the case of inulin.
Link: https://link.springer.com/article/10.1007/s10499-015-9902-y
Effects of dietary barley on rainbow trout exposed to an acute stress challenge
Autori: Pinedo-Gil J, Martín-Diana AB, Bertotto D, Sanz-Calvo MÁ, Jover-Cerdá M, Tomás-Vidal A
Riferimenti: Aquaculture (2019) 501, pp. 32-38
Summary: The present study evaluates the effect of dietary barley, based on its potential stress-relieving properties, on rainbow trout under acute stress challenge (hypoxia and crowding) and their recovery. Diets were formulated containing increasing barley concentrations (0, 4, 8, 16, 32%). Cortisol on plasma and fin, glucose and lactate plasma levels and malondialdehyde (MDA) in muscle were determined under normoxia before the stress test (basal levels), 30 min after the acute stress challenge and also during normoxia recovery (6 and 12 h after the stress). Results showed that at basal levels the inclusion of barley had no influence on cortisol, glucose nor on lactate values. After 30 min from the stress challenge, there was a significant increase in cortisol, glucose and lactate concentration in fish of all groups. Plasma cortisol showed the lowest levels in fish fed with diets at a medium (8%) of barley concentration and returned to basal levels 6 h after the stress stimulus with no differences between diets. Glucose values showed a less clear tendency 30 min after the stress challenge with lower levels in the control group, fish fed with 8% and 32% of barley in the diets and returned to basal levels in almost all the groups only 12 h after the stress challenge. Lactate showed the same trend as with glucose after the stress challenge but it returned to basal levels in 6 h. Interestingly, there was a significant decrease of lipid oxidation (MDA) in muscle soon after the stress test of fish fed with the highest barley levels. The present results suggest a potential positive effect of dietary barley on trout stress response. Previous article in issue
Link: https://www.sciencedirect.com/science/article/pii/S0044848618305003
Effects of dietary inclusions of red beet and betaine on the acute stress response and muscle lipid peroxidation in rainbow trout
Autori: Pinedo-Gil J, Martín-Diana AB, Bertotto D, Sanz-Calvo MÁ, Jover-Cerdá M, Tomás-Vidal A
Riferimenti: Fish Physiology and Biochemistry (2018) 44 (3), pp. 939-948
Summary: This study evaluates the effects of red beet (RB) and betaine on rainbow trout submitted to an acute stress challenge. A control diet was compared with four experimental diets in which red beet (14 and 28%) and betaine (0.9 and 1.63%) were incorporated in different concentrations according to a factorial design. Cortisol in plasma and fin, glucose and lactate plasma levels, and malondialdehide (MDA) in muscle were all measured before the stress challenge and 30 min and 6 and 12 h after the stress challenge as parameters to determine the diet effects. RB and betaine had no effect on cortisol, glucose, and MDA basal levels. However, lactate basal levels were significantly lower on fish fed with RB and betaine. Thirty minutes after the stress challenge, there was a significant increase in plasma and fin cortisol, glucose and lactate concentrations, although fish fed with diets containing RB and betaine showed significantly higher plasma cortisol values. MDA values of fish fed with 14% RB and 0.9% betaine were significantly higher than MDA values from fish fed with 28% RB and 1.63% betaine. After 6 and 12 h, plasma and fin cortisol and lactate levels recovered in a similar trend. Glucose plasma levels recovered in almost all groups 12 h after the stress. Also, MDA values recovered basal levels after 6 and 12 h. RB and betaine did not enhance the tolerance to the stress challenge compared to the control group, although the presence of these ingredients had no negative effect on any of the stress indicators.
Link: https://link.springer.com/article/10.1007%2Fs10695-018-0483-3
Feeding frequency differently affects post prandial patterns of plasma glucose, insulin and insulin-like growth factor I in European sea bass (Dicentrarchus labrax)
Autori: Messina M, Sànchez-Gurmaches J, Navarro I, Gutierrez J, Bertotto D, Tibaldi E, Tulli F
Riferimenti: Turkish Journal of Fisheries and Aquatic Sciences (2014) 14 (4), pp. 921-928
Summary: The aim of this study was to investigate theeffects of feeding frequency on post-prandialpattern of circulating glucose, insulin and IGF-I(insulin-like growth factor-I) in European sea bass (D.labrax). Fish (average body weight 72.1±2 g) were randomly allocated in 12 tanks, reared in a closed thermoregulated recirculating system and fed a commercial diet at a fixed ration (1.5% body weight) for 7 weeks.Six fish groupswere fed the ration in one meal a day (08:30am), while six fish groups were offered the same rationin two daily meals (08:30am and 04:30pm) according to a complete random design.Plasma insulin mean level was affected by the splitting up of the ration(14.4 vs15.2 ng/ml,P<0.05, one meal and two meals/day, respectively) and showed a bimodal profile depending on the meal administration. The level of circulating glucose was slightly affected by feeding pattern with an increase of glycaemia after each meal. The daily pattern of plasma IGF-I did not appear related to meal administration. Results show that post prandial plasma glucose, insulin and IGF-I are differently affected by the meal administration pattern in sea bass due to their physiological role in maintaining the internal homeostasis.
