Effect of dietary chitosan on the growth performance, intestinal histology and growth-related gene expression in stellate sturgeon (Acipenser stellatus) juveniles.

As sturgeon breeding has proliferated, there has been a heightened demand for growth stimulators in their diets. This study aimed to determine the impact of dietary chitosan on growth performance, whole-body proximate composition, growth-related gene expression, and intestinal histology in juvenile Acipenser stellatus. A total of 180 A. stellatus juveniles with an average weight of 31.90 ± 0.73 g were fed with diets containing 0 (control), 1.5, 3.0, 4.5, and 6.0 g chitosan.kg-1 basic diet for eight weeks. The findings revealed a significant enhancement in growth performance with rising chitosan concentrations. Furthermore, chitosan supplementation upregulated the expression of the growth hormone gene in both brain and liver tissues. In liver samples, the most pronounced expression of the insulin-like growth factor-1 gene was noted at 6.0 g chitosan.kg-1, while in brain samples, peak expressions were observed in both the 4.5 and 6.0 g chitosan.kg-1 treatments. While the whole-body proximate composition remained relatively stable, there was a notable decrease in whole-body lipids with the escalation of chitosan dosage. Intestinal villi dimensions, both height and width, were amplified in the chitosan-supplemented groups compared to controls. In summation, chitosan supplementation showed promise in bolstering growth performance, refining intestinal morphology, and enhancing growth-related gene expression. Analysis of the polynomial regression of weight gain and specific growth rate revealed that the optimum dietary chitosan requirements in A. stellatus were 5.32 and 5.21 g chitosan.kg-1, respectively.

The first record of Ascocotyle (Phagicola) longa (Digenea: Heterophyidae) metacercariae as the fish-borne zoonotic trematode in Chelon auratus and Chelon saliens (Pisces: Mugilidae) around the cage culture in the Caspian Sea, Iran

As a matter of fact, there has not been any reportage of the parasite of Ascocotyle (Phagicola) longa Ransom, 1920 from the Caspian Sea, Iran. During two years, April 2017 until 2018, 158 specimens of mullet fish, Chelon auratus and Chelon saliens (Risso, 1810) were collected and carefully examined considering the standard parasitological methods. Interestingly, the metacercaria was found in the stomach and intestine of the mullets. Morphological and morphometric analyses indicated that this parasite species belongs to Ascoctyle (Phagicola) longa. Overall infection mean intensity (52.1±128.3), mean abundance (14.8±71.9) and prevalence (28.5%) were calculated in mullets. Differences in the infection level of Ascocotyle (Phagicola) longa in relation to fish species, location and sampling years are determined and discussed. So that the mean intensity of this parasite is significantly different in the two locations of Anzali and Kiashahr (X2=13.35, df=1, p=0.00<0.05) and the mean intensity between mullet species (X2=5.49, df=1, p=0.019<0.05) is significantly different. In fact, A. (Phagicola) longa is a widespread and rife fishborne zoonotic parasite and also one of the most notable agents of human heterophyosis observed in the Caspian Sea.

The response of benthic foraminifera to aquaculture and industrial pollution: A case study from the Northern Persian Gulf.

The aquaculture and industrial sewage impacts on benthic foraminifera investigated at two reefs across the northern Persian Gulf. The foraminifera assemblages at a single sewaged reef were compared with two non-sewaged reefs. A low-diversity assemblage, dominated by stress-tolerant species Quinqueloculina sp. and larger symbiont-bearing Amphistegina sp., was characteristic of the industrial sewaged reef. The opportunistic species Ammonia sp. and Elphidium sp. were common in aquaculture sewaged reef. The density of foraminifera in sewaged reefs was lower than non-sewaged reefs. The lower diversity was only detected in the industrial sewaged reef. Assemblage structure was significantly different between sewaged and non-sewaged reefs. The industrial sewaged reef displayed high FORAM Index values (>4.0), reflecting favorable environments for supporting relatively healthy reefs. FORAM Index in aquaculture sewaged reef ranged from 2.0 to 4.0 indicated that the water with organic pollution may support living coral community, but any damage would not be followed by recovery.

Toxic effects of magnesium oxide nanoparticles on early developmental and larval stages of zebrafish (Danio rerio).

Magnesium oxide nanoparticles (MgONPs) are used in medicine, manufacturing and food industries. Because of their extensive application in our daily lives, environmental exposure to these nanoparticles is inevitable. The present study examined the effects of MgONPs on zebrafish (Danio rerio) early developmental stages. The results showed that, at different concentrations, MgONPs induced cellular apoptosis and intracellular reactive oxygen species. The hatching rate and survival of embryos decreased in a dose dependent manner. The 96-h LC50 value of MgONPs on zebrafish survival was 428 mg/l and the 48-h EC50 value of MgONPs on zebrafish embryo hatching rate was 175 mg/l. Moreover different types of malformation were observed in exposed embryos. The results demonstrate the toxic effects of MgONPs on zebrafish embryos and emphasize the need for further studies.

Dichelyne (Dichelyne) spinigerus sp. nov. (Nematoda: Cucullanidae) from the marine fish Otolithes ruber (Sciaenidae) off Iran and first description of the male of Philometra otolithi Moravec et Manoharan, 2013 (Nematoda: Philometridae).

Recent parasitological examinations of the marine perciform fish (tigerteeth croaker) Otolithes ruber (Bloch et Schneider) (Sciaenidae) from off Iran yielded one new and one previously known nematode species: Dichelyne (Dichelyne) spinigerus sp. nov. (Cucullanidae) from the host's intestine in the Persian Gulf and Philometra otolithi Moravec et Manoharan, 2013 (Philometridae) from the ovary in the Persian Gulf and the Sea of Oman. The new species D. spinigerus is mainly characterized by the tail tip of both sexes terminating in two shaply pointed spikes (one dorsal and one ventral) and bearing a pair of minute lateral cuticular spines at its base, situation of both deirids and the excretory pore well posterior to the level of the posterior end of oesophagus, absence of a precloacal sucker and the presence of one or two intestinal caeca. The male and small mature females of the gonad-infecting species P. otolithi are described for the first time, based on light and scanning electron microscopical studies. The male of P. otolithi is most similar to that of P. johnii Moravec et Ali, 2013, but differs from it by the structure of the cephalic end and the number of caudal papillae; both species also differ from each other by the presence of transverse lamellae in the buccal cavity of gravid and subgravid females of P. otolithi, which are missing in those of P. johnii.

Two philometrids (Nematoda: Philometridae) infecting the tigertooth croaker Otolithes ruber (Bloch & Schneider) (Teleostei: Sciaenidae) off Iran, including erection of a new genus.

Two philometrid nematodes (Philometridae) are described from the marine perciform fish (tigertooth croaker) Otolithes ruber (Bloch & Schneider) (Sciaenidae) from off Iran: Clavinemoides annulatus n. g., n. sp. based on female specimens from the caudal fin of fish from the Persian Gulf and Philometra otolithi Moravec & Manoharan, 2013 from subgravid and nongravid females collected from the ovary of fishes in the Sea of Oman and the Persian Gulf. The monotypic genus Clavinemoides n. g. is mainly characterised by a triangular oral aperture, a markedly large anterior oesophageal bulb, a distinctly annulated body and numerous fine elevated transverse cuticular bands. The finding of P. otolithi in Iranian waters represents a new geographical record of this parasite species. An updated key to the genera of the Philometrinae Baylis & Daubney, 1926 is provided.