In marine fish producing pelagic eggs, the acquirement of buoyancy by the eggs through the hydration process is a key event
of reproduction; moreover, the yolk proteolysis, which leads to buoyancy, ...seems to affect the fertility and survival of the
spawned eggs. Recently we demonstrated that cathepsin D is the aspartic protease responsible for this intraoocytic processing
of vitellogenin into yolk proteins. In the present study, we isolated, cloned, and sequenced the cDNA encoding cathepsin D
and studied expression of the message by Northern blotting and whole-mount in situ hybridization.
The full-length seabream cathepsin D cDNA is 1837 base pairs long, encoding a protein of 400 amino acids (aa) consisting of
a signal peptide of 19 aa, a prosequence of 44 aa, and a mature peptide of 336 aa. An absolute sequence conservation at the
aspartyl residues (+33 and +221) was found, and there are three potential N -glycosylation sites at +70, aa +189, and aa +274. The aa sequence of seabream cathepsin D reveals a high degree of sequence
similarity with cathepsin D mRNAs from other organisms (73% sequence homology to mouse and rat, 72% to human and trout, 69%
to chicken, 66% to pig, and 65% to Xenopus ).
The cathepsin D mRNA in floating eggs was present as a single band that was approximately 1.9 kilobases (kb) in size, while
in the sinking eggs there were several fast-migrating bands (size range 1.3â0.2 kb). Whole-mount hybridization was used to
investigate transcription of cathepsin D in the developing embryo; during the hatching period, cathepsin D mRNA-positive cells
were distributed in a wide region between the trunk and the tail, and in the ventral region over the yolk ball. The highest
levels of cathepsin D enzymatic activity were found in the sinking eggs and during the hatching period of embryonic development.
These data suggest that cathepsin D can be considered a possible marker for egg quality.
A short-term experiment (7 days) was carried out to study cadmium accumulation and metallothionein (MT) gene expression in the liver of the Antarctic teleost Trematomus bernacchii when exposed to 2.0 ...mg Cd L
−1
seawater. Metal determinations were carried out by differential pulse anodic stripping voltammetry while MT gene expression was determined by the Real Time PCR Detection System. In controls, the Cd concentration and the MT gene expression remained practically constant during the experiment (8.8 ± 0.9 µg g
−1
d.w. and 1.0 ± 0.2 mRNA a.u., respectively). In exposed organisms, while Cd increased almost linearly with time, up to 30 ± 2 µg g
−1
d.w., i.e. by a factor of ∼3.5 in 7 days, MT gene expression, after a little delay, increased almost exponentially up to a value of 86 ± 25 mRNA a.u. after 7 days, by a factor of ∼90. These results confirm the potential usefulness utility of T. bernacchii as a bioindicator of environmental pollution in Antarctica.
: Numerous studies have described the presence of an intragonadal IGF system involved in regulation of gametogenesis in teleost fish. In the present study, the in vivo effects of estradiol‐17β (E2) ...and growth hormone (GH) exposure on IGF‐I, IGF‐II, IGF1R, and IGFBP2 gene expression in sea bream ovary were monitored by RT‐PCR during prereproductive and reproductive periods. The evidence demonstrates that both hormones investigated here affect the ovarian IGF system, showing that it is not only under GH control, but also can be regulated by sexual hormones; this hormonal modulation is related to reproductive phase.
In this paper, the effects of an estrogenic compound, 4-nonyl-phenol (NP), on the amphibians Rana esculenta and Triturus carnifex are described together with those on sexual differentiation in ...Xenopus laevis. NP increased plasma vitellogenin in male frogs and newts in a dose-related manner; moreover, inhibitory effects on gonadotropin and prolactin (PRL) secretion by pituitary were found together with an elevation of plasma androgens. NP treatment also caused a remarkable increase in number of prolactin-immunolabeled cells, suggesting that xenoestrogen might induce, at least in the newt pituitary, a PRL accumulation possibly due to a reduction of the hormone release. In addition, both NP and bisphenol A caused feminization by increasing the percentage of female phenotypes in X. laevis, and the in vivo effects were more pronounced than those of estradiol-17β.
1 Dipartimento di Scienze Morfologiche e Biochimiche
Comparate, Università degli Studi di Camerino, 62032 Camerino
(MC) Italy; 2 Istituto di Scienze del
Mare, Università di Ancona, 60131 Ancona, ...Italy; and
3 Department of Biological Sciences, University of
Calgary, Calgary, Alberta, Canada T2N 1N4
Experiments were carried out to study in
vitro the effects of 17 -estradiol (E 2 ), homologous
pituitary homogenate (HPH), and recombinant red sea bream growth
hormone (sbGH) on vitellogenin (VTG) secretion from cultured sea bream
liver fragments. Basal secretion of VTG was found to be significantly
higher in the prespawning period, compared with sea bream liver in the
spawning and postspawning periods. Similarly, the sea bream liver
obtained during the prespawning period responded more significantly to
treatments with E 2 , HPH, or sbGH compared with sea bream
liver during spawning. In the postspawning period, treatments with
E 2 , HPH, or sbGH were without significant effect on VTG
secretion level in sea bream liver. The level of E 2
receptors was also analyzed by Western blot analysis. The result
demonstrates a significantly higher level of E 2 receptors in the sea bream liver at the prespawning stage compared with those at
the spawning and postspawning stages. The findings support the
hypothesis that homologous upregulation of estrogen receptors plays an
important role in the estrogen-sensitive control of VTG synthesis in
the sea bream liver.
vitellogenin induction; hormones; estradiol receptor
In July 2003, the finding of a newly settled population of Siganus luridus at Linosa Island (Sicily Strait, Mediterranean Sea) gave us the unusual opportunity to examine the reproductive condition of ...a Lessepsian migrant during early phases of colonization. Aspects of gonad morphology, fecundity, atresia and oocyte dynamics were investigated by using 43 pioneer specimens collected in concomitance with their first record in the Pelagie Islands. Ovarian development was consistent with the group-synchronous type, and testicular organization was of the unrestricted spermatogonial testis type, with cystic spermatogenesis. Both males and females had reached final stages of gonad maturation. The rates of follicular atresia were moderate: out of 17 adult females, 10 individuals did not present atretic oocytes; six exhibited <15.1% of secondary growth phase (SGP) oocytes in α-atresia, while one female presented 45.7% of SGP in α-atresia. Fecundity estimates did not diverge from what was observed in a reference population along the Lebanese coast. Absolute fecundity ranged from 115 739 to 740 433 oocytes per female (16.5-24.5 cm LT). Relative fecundity ranged from 1239 to 3162 oocytes g⁻¹, with a mean of 1885 ± 868 oocytes g⁻¹. Our observations indicated that these early settled siganids are reproductively active at Linosa and suggested the forthcoming of self-maintaining populations across the central Mediterranean area.
In the last years, an increasing number of studies reported that food pollution represents a significant route of exposure to environmental toxicants, able to cause mild to severe food illnesses and ...health problems, including hormonal and metabolic diseases. Pollutants can accumulate in organisms and biomagnify along the food web, finally targeting top consumers causing health and economic problems. In this study, adults of gilthead sea bream, Sparus aurata, were fed with diets contaminated with Bisphenol A (BPA) (4 and 4000 μg BPA kg−1 bw day−1) and Di-isononyl phthalate (DiNP) (15 and 1500 μg DiNP kg−1 bw day−1), to evaluate the effects of the contamination on the muscle macromolecular composition and alterations of its texture.
The analysis conducted in the muscle using infrared microspectroscopy, molecular biology and biochemical assays, showed, in fish fed BPA contaminated diets, a decrease of unsaturated lipids and an increase of triglycerides and saturated alkyl chains. Conversely, in fish fed DiNP, a decrease of lipid content, caused by a reduction of both saturated and unsaturated chains and triglycerides was measured. Protein content was decreased by both xenobiotics evidencing a novel macromolecular target affected by these environmental contaminants. In addition, in all treated groups, proteins resulted more phosphorylated than in controls. Calpain and cathepsin levels, orchestrating protein turnover, were deregulated by both xenobiotics, evidencing alterations of muscle composition and texture. In conclusion, the results obtained suggest the ability of BPA and DiNP to modify the muscle macromolecular building, advising this tissue as a target of Endocrine-Disrupting Chemicals (EDCs) and providing a set of biomarkers as possible monitoring endpoints to develop novel OEDC test guidelines.
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•BPA and DiNP in the diet affect skeletal muscle macromolecular building.•BPA and DiNP in the diet affect seabream muscle nutritional properties.•Dietary BPA and DiNP administration increases skeletal muscle proteolytic system activity.
Abstract
The antagonistic and/or synergistic effects of different chemical compounds were examined in the marine teleost, Gobius niger, by testing a series of biomarkers involved in fish ...reproduction. Among the biomarkers analysed, vitellogenin (VTG) and zona radiata proteins (ZRP) are key molecules involved in reproduction, widely used to detect the presence of pollutants in the marine environment, while heat shock protein 70 (HSP70) and cathepsin D (CATD) have recently been introduced as bioindicators of endocrine disruption. The detection of VTG and ZRP in the plasma of wild male specimens is universally accepted as an early warning signal of environmental pollution. The evaluation of VTG, ZRP and CATD expression demonstrated the oestrogenic effect of nonylphenol on both male and female fish; on the contrary beta-naphthoflavone behaves mainly as an anti-oestrogen although, when co-injected with compounds with oestrogenic activity, it enhances ZRP gene expression. Regarding the chaperone, all treatments stressed the fish, inducing an increase in HSP70 gene transcription. The results obtained underlined the importance of testing the effects of compound mixtures: fish in the wild are subjected to a blend of chemicals and the effects observed derive from the synergic or antagonistic interactions of these compounds.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Lactobacillus delbrueckii ssp.
delbrueckii (AS13B), isolated from the gut of adult
Dicentrarchus labrax, was administered live to developing sea bass using rotifers and
Artemia as live carriers. ...Immune-related gene transcripts were quantified in post-larvae at day 70 post-hatch (ph) and histology, electron microscopy and immunocytochemistry of the intestinal tissue were performed at day 74 ph. Since the probiotic was orally administered the studies were focused on intestinal immunity.
In treated fish gut integrity was unaffected, while the density of T-cells and acidophilic granulocytes in the intestinal mucosa was significantly higher than in controls. Probiotic-induced increases in intestinal T-cells and total body
TcR-β transcripts are first reported in fish. Significantly lower
IL-1β transcripts and a trend towards lower
IL-10,
Cox-2 and
TGF-β transcription were found in the treated group.
Evidence is provided that early feeding with probiotic-supplemented diet stimulated the larval gut immune system and lowered transcription of key pro-inflammatory genes.
In the present study a Lactic Acid Bacteria (LAB) strain
Lactobacillus delbrueckii delbrueckii, acting as probiotic, was administered to
Dicentrarchus labrax (European sea bass) juveniles for a short ...(25 days) and a long (59 days) time and the effects of the bacteria on gut colonization in sea bass juveniles cortisol level and growth were evaluated with respect to fish fed on live preys solely (control group). Measures of body weight and standard length (S.L.) were performed to assess juveniles growth, while cortisol, a hormone directly involved in stress responses, was chosen as a stress marker. In addition, the expression of two antagonistic genes involved in muscular growth (IGF-I and myostatin (MSTN) was analyzed through real-time PCR. Fish fed on live preys added with
L. delbrueckii delbrueckii showed a high gut colonization by this Lactic Acid Bacteria strain. In the same fish a significantly (
p
<
0.05) lower cortisol level was observed with respect to those fed on live preys solely (control 5.1
±
0.47 ng/g; group A: 3.6
±
0.36 ng/g; group B: 4.5
±
0.48 ng/g). In addition, an increase of IGF-I transcription was observed in fish treated with LAB, being IGF-I mRNA levels six times higher in both treated groups with respect to the control (control: 1
±
0.01 a.u.; group A: 6.63
±
0.18 a.u.; group B: 6.16
±
0.15 a.u.). On the contrary, MSTN mRNA transcription was significantly inhibited in treated groups (control 1
±
0.02 a.u.; group A: 0.71
±
0.01 a.u.; group B: 0.26
±
0.003 a.u.). These results are in agreement with the increase of body weight recorded in this study. Fish fed on LAB showed 81% higher body weight in long treated group and 28% in short treated one with respect to control.
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