Search

The thin-lipped grey mullet, Liza ramada, a commercially significant fish in Egypt, was studied for its expression patterns along the brain-pituitarygonad axis in female L. ramada during the spawning season of 2022 in both captive and wild habitats. The inspected genes included Kiss2, Gpr54, Gnrh1, and Drd2 genes in the brain and ovary, as well as Lhβ, Fshβ, and Slα genes in the pituitary and ovary. Relative expressions of all studied genes either in the brain, or pituitary, and ovary were higher in ripe females than in immature ones. Captive females had higher Drd2 gene expressions; nevertheless, mature wild females had higher expression values for the other investigated genes that were measured in the brain, or pituitary and ovary. The study found correlations between gene expression patterns in wild and captive females (P< 0.05), suggesting that confinement may affect reproductive physiology. The findings suggest focusing on hormones for artificial fertilization therapies in confined females. [ABSTRACT FROM AUTHOR]

The current research work provided insights into the expression patterns of key genes in the BPG axis of Mugil cephalus females, highlighting differences between wild and captive environments during the spawning season. The investigated genes include Kiss2, Gpr54, Gnrh1, and Drd2 in the brain and ovary, as well as Lhβ, Fshβ, and Slα in the pituitary and ovary. The finding indicated that the relative expression of all examined genes is elevated in mature females compared to immature ones across all examined tissues (brain, pituitary, and ovary). The observation that the expressions of the examined genes in wild females of M. cephalus are highly correlated, either directly or inversely, with their counterparts in captive females, indicated a connection between gene expression patterns and the different environments (wild vs. captive). The results between wild and captive females were in significant values (P≤ 0.05). Overall, the observed correlations and significant differences in gene expression proposed potential impacts of captivity on the reproductive physiology of these fish. [ABSTRACT FROM AUTHOR]

El-Manzala Wetland is known to be of the most significant sources of inexpensive different fish species for human consumption in Egypt. The Lake receives pollution from various sources; domestic wastewater, industrial wastewater, and agricultural drainage directly without any treatments, which leads to many environmental disorders. The following research was conducted for lake water quality evaluation and how it impacts the expression of the aromatase (CYP19a&b) genes in Oreochromis niloticus tissues at different locations of El-Manzala Lake. Sampling was done during the summer of 2018 when water and fish samples were collected from five different locations of El-Manzala Lake. It was found that the studied locations recorded hazardous concentrations of polyaromatic hydrocarbons (PAHs) that may cause significant defects to aquatic organisms except in the reference location and affect the expression of CYP19a&b genes. The relative gene expressions of CYP19a in the ovary and the testis were measured and recorded in positive ranges, but revealed the controversial expression pattern of CYP19b gene in the brain tissues. Our results revealed that PAHs discharges at El-Manzala Lake are correlated with the gene expression of CYP19 genes. The current findings suggested a correlation between biomarkers response and wastewater exposure as stressors. Besides, the assessed multiple general health indicators give prospective insights for Nile tilapia adaptive pattern and monitoring of pollution of freshwater ecosystems. [ABSTRACT FROM AUTHOR]

The cytochrome P450 superfamily (cyp) is a unique, diverse group of enzymes that catalyze the oxidation of organic pollutants such as polycyclic hydrocarbons (PAHs). Both levels of cyp1a expression in Oreochromis aureus organs and the accumulation of PAHs in water were determined in five different locations of Lake Manzala; namely, El-Inaniya, El-Serw, El- Temsah, El-Gamil, and El-Bashtir during December 2011. The area of Al- Qanater was included as a reference site from the River Nile. The cyp1a gene was highly expressed in the liver of all fish populations followed by gill, testis, ovary and muscle. The liver and gonads of the fish population in the El-Gamil location exhibited the greatest cyp1a gene expression, while the gills and muscles in the El-Serw fish population were the highest in the expression pattern among Lake Manzala regions. A higher accumulation profile of PAHs in water was found in the El-Gamil location followed by El-Serw, El-Bashtir, El-Inaniya and El-Temsah. The correlation between PAHs and cyp1a expression of fish organs showed a significant positive correlation. The highest positive correlation was observed between the gill and liver based on the expression of cyp1a. The obtained cDNA of the cyp1a gene from O. aureus was 569 base pairs, and it exhibited 86.8% of the identity with cyp1a of O. niloticus. The phylogenetic tree of cyp1 family genes showed a closer relationship between cyp1a and cyp1d subfamily compared to cyp1b or cyp1c subfamily members. The results showed the sensitivity of cyp1a expression in fish as a biomarker for PAHs concentrations in the regions of Lake Manzala. [ABSTRACT FROM AUTHOR]

We indicated that two P450s (1A9 and 1C1) from Japanese eel (Anguilla japonica) metabolized 7-ethoxycoumarin, 7-ethoxyresorufin, and flavanone. At first, we constructed expression vectors for two types of P450 (1A9 and 1C1). The reduced CO-difference spectra of Escherichia coli cells transformed with these plasmids showed Soret peaks (450 nm) that were typical of P450s. We performed bioconversion experiments in which substrates were added directly to incubation medium. The resulting metabolite(s) were extracted and analyzed by high-performance liquid chromatography and spectrofluorometer. Incubation of 50 nmol 7-ethoxyresorufin with P450 1C1 yielded 0.773 nmol of deethylated product, whereas 50 nmol 7-ethoxycoumarin resulted in 4.76 nmol. P450 1A9 metabolized 50 nmol of 7-ethoxyresorufin and 7-ethoxycoumarin to yield 6.54 and 20.9 nmol of deethylated product, respectively. Incubation of 50 nmol flavanone with P450 1C1 yielded 1.46 nmol and 0.69 nmol of products, whereas 50 nmol flavanone with P450 1A9 resulted in 1.10 nmol. In this system, 4'-hydroxy flavanones were formed by P450 1A9 and P450 1C1. P450 1A9 also metabolized 50 nmol of 17 beta-estradiol to yield 4.25 nmol of product. In this system, 2-hydroxy estradiol was formed by P450 1A9 using 17 beta-estradiol as a substrate. This study is the first to identify the substrates that P450 1C1 and 1A9 metabolize.

An experiment was conducted to assess the potential of the European eel, Anguilla anguilla for earthen pond aquaculture without supplementary feeding at Lake Manzala, Egypt. Juvenile A. anguilla of mean length 11.7 cm and 2.4 g weight were stocked in earthen ponds measuring 3 feddans (about 12,600 m2) and 1 m deep. Stocking was done in May 2003 at a rate of 5000 fish feddan(-1) in a polyculture system including tilapia and mullets and fed mainly on natural occurring prey (natural spawned tilapia) and small shrimp. The eels were culture for a period of 2 years, May 2003 to April 2005. Sampling for growth and survival were evaluated yearly. At the end of the culture period, the gross weight of the harvested eels was measured and the net pond production calculated by the difference between weight stocked and weight harvested. Temperature varied from 11.5 to 28.2 degrees C and 12.2 to 29.3 degrees C; P(H), 7.3 to 8.9 and 7.5 to 8.8; Dissolved Oxygen (DO), 5.2 to 9.8 mg L(-1) and 4.1 to 8.3 mg L(-1); and Salinity, 2.5 to 5.5 psu and 3.0 to 6.8 psu for first year and second year, respectively. At the end of the culture period, A. anguilla attained average weight of 121.4 g fish(-1) at the end of the first year and a weight range of 152.5 to 430 g fish(-1) with an average of 280.36 g fish(-1) at the end of the second year. Survival rate ranged from 91% during the first year to 100% during the second year. Net eel production was 540.18 kg feddan(-1) at the end of the first year and 723.36 kg feddan(-1) at the end of the second year. Daily increments in weight per fish were 0.33 and 0.44 for first and second year, respectively. This experiment demonstrated the possibility of cultivation of eels as well as the higher growth rate in earthen ponds. The aquaculture strategy of eel with high stocking densities through low cost artificial feeds are recommended in future studies.

The present study provides a characterization of water quality and plankton samples in earthen fish pond in Rajshahi, Bangladesh. Sampling was done over a period of six months, running from October, 2004 through March, 2005. All the water quality parameters were within the optimal ranges for plankton productivity. Temperatures varied from 19.75 to 27.25 degrees C; transparency, 24.75-29.50 cm; pH, 6.62-7.85; Dissolved Oxygen (DO), 3.87-5.85 mg L(-1); free CO2 5.25-7.25 mg L(-1) and bicarbonate (HCO3) alkalinity, 81.25-147.5 mg L(-1). Analyses of plankton samples recorded a total of 5 classes phytoplankton viz.; Bacillariophyceae, Chlorophyceae, Cyanophyceae, Dinophyceae, Euglenophyceae and 2 classes of zooplankton; Crustacea and Rotifera. The phytoplankton population was comprised of 17 genera belonging to Cyanophyceae (5 classes, 34.47%), Bacillariophyceae (3, 13.87%), Cyanophyceae (3, 34.48%), Euglenophyceae (3, 10.68%) and 1 to Dinophyceae (6.50%). The zooplankton population consisted of 10 genera belonging to Rotifera (4, 40.13%) and Crustacea (6, 59.87%). Phytoplankton and zooplankton abundance varied from 60800 to 239400 units/l and 7620 to 12160 units/l, respectively. It is concluded that the phytoplankton groups provide the main support for earthen pond aquaculture in the pond compared to zooplankton classes. The information provides for more research to compare water quality and pond plankton characteristics in earthen aquaculture systems with and without fish stocking. Further studies on the seasonal changes of water quality parameters and its effects on plankton production in the fish ponds and all year extended monitoring is recommended in future studies.

Cytochrome P450 (CYP) genes, which make up a large gene superfamily, are known to play an important role in drug metabolism. The CYP1 family, one of the gene families of the CYP superfamily, has three subfamilies of genes whose sequences have been deposited in the GenBank/EMBL thus far: CYP1A, CYP1B, and CYP1C. Mammals as well as fish confront numerous foreign chemicals in the environment that may accumulate to toxic levels unless they are metabolized and eliminated by processes largely mediated by CYP enzymes. A new complementary DNA of the CYP1C subfamily encoding CYP1C2 was isolated from the carp liver after a single intraperitoneal injection of beta-napthoflavone (BNF). The full-length cDNA obtained contained a 5' noncoding region of 198 bp, an open reading frame of 1575 bp coding for 524 amino acids and a stop codon, and a 3' noncoding region of 531 bp. The predicted molecular weight of the protein was approximately 59.3 kDa. The amino acid sequence deduced from the carp CYP1C2 sequence showed a similarity of 76.6% with that deduced from our previously reported carp CYP1C1. It exhibited similarities of 77.3, 73.7, and 76.4% with those deduced from scup CYP1C2, scup CYP1C1, and Japanese eel CYP1C1 sequences, respectively. Carp CYP1C2 cDNA showed similarities with reported CYP1Bs of teleosts and mammals, namely, 47.6, 45.3, 45.7, 44.0, and 44.6% for carp, plaice, human, rat, and mouse CYP1B1s, respectively, while it exhibited a similarity of 49.0% with carp CYP1B2. The carp CYP1C2 sequence was aligned with the CYP1 sequences and has been deposited in the GenBank/EMBL data bank with the accession number AY437777. The phylogenetic tree constructed using fish and mammalian CYP1 sequences suggested a closer relationship of CYP1C with CYP1B than with CYP1A. The tree showed possibile existence of CYP1C subfamily genes in mammalian species. Northern blot analysis of the liver, intestines, kidneys, and gills revealed a distinct induced expression only in the kidneys, with no detectable constitutive expression in the other organs studied.

Some forms of cytochrome P450 (CYP) genes are known to be induced by xenobiotics such as dioxins. Induction of the CYP1A gene is mediated by an aryl hydrocarbon receptor (AHR) which binds to a specific nucleotide sequence called a dioxin-responsive element (DRE) located in the 5' enhancer region of the gene. Functional analysis of the regulatory region of the eel CYP1A gene had shown that a 654-bp region near the basal promoter, containing no DREs but three motifs that resemble estrogen-responsive element (ERE) halfsites, contributes substantially to the induced expression. Considering the importance of non-DRE elements in CYP1A gene induction, we investigated the role of ERE-like motifs using a point mutation technique. The regulatory region of the eel CYP1A gene was identified by creating mutations in all three ERE half-sites simultaneously or individually. The regulatory region constructs were cloned upstream of the luciferase gene in an expression vector which was microinjected into medaka ova. Expression of luciferase as a foreign gene in medaka fry exposed to 3-methylcholanthrene (3-MC)-treated feed was measured by competitive PCR analysis. Mutation in all the three ERE half-sites reduced expression to 10%. Mutation in ERE(-2) or ERE(-3) reduced the expression to 50%, whereas mutation in ERE(-1) did not affect the induction. The two functional half-sites of the eel CYP1A gene are palindromic to each other and appear to constitute the full-ERE.

Cytochrome P450 (CYP) genes, which make up a large gene superfamily, are known to play an important role in drug metabolism. The levels of expression of CYP genes in the tissue of fish inhabiting polluted areas have been used extensively in biomonitoring studies as indicators of dioxin pollution. Complementary DNA of cytochrome CYP1B1 was isolated from carp (Cyprinus carpio) liver 24 h after the injection of 3-methylcholanthrene (3-MC). The full length cDNA obtained contained a 5' noncoding region of 178 bp, an open reading frame of 1593 bp coding for 530 amino acids and a stop codon, and a 3' noncoding region of 1599 bp. The predicted molecular weight of the encoded protein was approximately 60.2 kDa. The deduced amino acid sequence exhibited an identity of 60.6% with reported CYP1B sequences of plaice CYP1B, and of 52.4, 51.4, and 50.3% with human, rat, and mouse CYP1B1s, respectively. It exhibited similarities of 48.4 and 47.3% with scup CYP1C2 and -1C1 sequences. The percent identities with CYP1A sequences showed lower values in the range from 35.3 to 39.5% with mammals and teleosts. The phylogenetic tree of the CYP1 family members constructed by the protein maximum likelihood method indicates that the carp CYP1B1 and plaice CYP1B share a common ancestry with the mammalian CYP1B1s. Carp treated with 3-MC showed expression of CYP1B1 in liver, intestine and gills with distinct induction except for the gills that showed marked constitutive expression. The presence of two successive signals in treated gills at low stringency hybridization may suggest the existence of another CYP1B member that is expressed in the gills of carp.

Cytochrome P450 (CYP) enzymes constitute a multigene family of many endogenous and xenobiotic substances. The CYP1 family is of particular interest in environmental toxicology because its members are dominant in the metabolism of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and aryl amines. A new complementary DNA of the CYP1B subfamily encoding CYP1B2 was isolated from carp liver after intraperitoneal injection with 3-methylcholanthrene (3-MC). The obtained full-length cDNA contained a 5'noncoding region of 161 bp, an open reading frame of 1593 bp coding for 530 amino acids and a stop codon, and a 3'noncoding region of 1457 bp. The predicted molecular weight of the protein was approximately 60.2 kDa. The deduced amino acid sequence of this cDNA was 91% similar to that of our previously reported carp CYP1B1; its similarities with those of the reported CYP1B1s of teleosts and mammals were 60.8, 54.4, 50.8, and 51.4% for plaice, human, rat, and mouse, respectively. The phylogenetic tree of fish and mammalian CYP1 sequences constructed by the protein maximum-likelihood method suggested a relatively recent divergence of CYP1B2 from CYP1B1 in the ancestor of carp and closely related species. Despite the structural similarity of CYP1B2 with CYP1B1, which showed induced expression in 3-MC-treated liver, intestine, and gills with marked constitutive expression in gills, CYP1B2 revealed induced expression in gills but not in liver or intestine, and no detectable constitutive expression in the tissues studied.