Molecular characterization and expression of the gene encoding aspartate aminotransferase from the Pacific oyster Crassostrea gigas exposed to environmental stressors

The Glucose-Succinate Pathway: A Crucial Anaerobic Metabolic Pathway in the Scallop Chlamys farreri Experiencing Heat Stress

Recently, the increase in marine temperatures has become an important global marine environmental issue. The ability of energy supply in marine animals plays a crucial role in avoiding the stress of elevated temperatures. The investigation into anaerobic metabolism, an essential mechanism for regulating energy provision under heat stress, is limited in mollusks. In this study, key enzymes of four anaerobic metabolic pathways were identified in the genome of scallop Chlamys farreri, respectively including five opine dehydrogenases (CfOpDHs), two aspartate aminotransferases (CfASTs) divided into cytoplasmic (CfAST1) and mitochondrial subtype (CfAST2), and two phosphoenolpyruvate carboxykinases (CfPEPCKs) divided into a primitive type (CfPEPCK2) and a cytoplasmic subtype (CfPEPCK1). It was surprising that lactate dehydrogenase (LDH), a key enzyme in the anaerobic metabolism of the glucose-lactate pathway in vertebrates, was absent in the genome of scallops. Phylogenetic analysis verified that CfOpDHs clustered according to the phylogenetic relationships of the organisms rather than substrate specificity. Furthermore, CfOpDHs, CfASTs, and CfPEPCKs displayed distinct expression patterns throughout the developmental process and showed a prominent expression in muscle, foot, kidney, male gonad, and ganglia tissues. Notably, CfASTs displayed the highest level of expression among these genes during the developmental process and in adult tissues. Under heat stress, the expression of CfASTs exhibited a general downregulation trend in the six tissues examined. The expression of CfOpDHs also displayed a downregulation trend in most tissues, except CfOpDH1/3 in striated muscle showing significant up-regulation at some time points. Remarkably, CfPEPCK1 was significantly upregulated in all six tested tissues at almost all time points. Therefore, we speculated that the glucose-succinate pathway, catalyzed by CfPEPCK1, serves as the primary anaerobic metabolic pathway in mollusks experiencing heat stress, with CfOpDH3 catalyzing the glucose-opine pathway in striated muscle as supplementary. Additionally, the high and stable expression level of CfASTs is crucial for the maintenance of the essential functions of aspartate aminotransferase (AST). This study provides a comprehensive and systematic analysis of the key enzymes involved in anaerobic metabolism pathways, which holds significant importance in understanding the mechanism of energy supply in mollusks.

Alterations in haemolymph proteome of Mytilus galloprovincialis mussel after an induced injury

A proteomic and biochemical approach was performed to assess the effects of an induced muscle injury on the haemolymph of bivalve molluscs. For this purpose, Mytilus galloprovincialis were exposed to puncture of adductor muscle for three consecutive days, and their haemolymph proteome was then compared to healthy animals using 2-dimensional electrophoresis (2-DE) to identify proteins that differed significantly in abundance. Those proteins were then subjected to tandem mass spectrometry and 6 proteins, namely myosin, tropomyosin, CuZn superoxide dismutase (SOD), triosephosphate isomerase, EP protein and small heat shock protein were identified. SOD and tropomyosin changes were verified by spectrophotometric measurements and western blotting, respectively. As some of the proteins identified are related to muscular damage and oxidative stress, other biomarkers associated with these processes that can be evaluated by automatic biochemical assays were measured including troponin, creatine kinase (CK), and aspartate aminotransferase (AST) for muscle damage, and SOD, trolox equivalent antioxidant capacity (TEAC) and esterase activity (EA) for oxidative stress. Significantly higher concentrations of troponin, CK, AST, and TEAC were observed in mussels after puncture, being also possible biomarkers of non-specific induced damage.

Effect of molecular crowding and ionic strength on the isothermal hybridization of oligonucleotides

The isothermal hybridization of complementary oligonucleotides, 15-mer, 25-mer, 35-mer, and a molecular beacon, was investigated under varying conditions of molecular crowding and ionic strength, using hypochromicity to follow strand pairing and polyethylene glycol as a crowding agent. Thermodynamic analysis of the results revealed the addition of counterions to the oligonucleotide backbones, DeltaPsi, to be dependent on the strand GC content and the molecular crowding. A decrease in DeltaPsi was observed, with both increasing GC% and solution PEG content. In contrast, the number of bound water molecules depended on the activity of Na(+), where two regimes were observed. At a(Na(+)) < 0.05 and increasing molecular crowding, water molecules were released into the DNA solutions, and oligonucleotide pairing was favored with both increasing hydrophobic forces, whereas at a(Na(+)) >or= 0.05, water molecules were bound to the strands, and the extent of double strand formation decreased with increasing PEG wt %.

Protective effects of propolis and related polyphenolic/flavonoid compounds against toxicity induced by irinotecan

Despite the excellent chemotherapeutic effect of irinotecan, its cytotoxicity and genotoxicity in normal cells remains a major problem in chemotherapy. This study was carried out to find whether propolis preparations and related flavonoids (quercetin, naringin) might enhance irinotecan-induced cytotoxicity to tumor cells in mice bearing Ehrlich ascites tumors (EAT) while protecting normal blood, liver, and kidney cells. The preparation of propolis and their flavonoids were given to mice intraperitoneally at a dose of 100 mg kg(-1) body weight for three consecutive days before the ip injection of EAT cells (2×10(6)). Irinotecan was administered ip at dose of 50 mg kg(-1) on days 3, 4, and 5 after tumor cell inoculation. The combination treatment resulted in substantial inhibition of the growth of EAT cells as well as treatment with quercetin or irinotecan alone, whereas other treatment by itself showed little effect. However, when mice were pre-treated with test components prior to irinotecan, the frequencies of irinotecan-induced micronuclei (MN) was decreased but in mice bearing tumor QU and EEP increased number of micronucleated cells. Propolis preparation and related flavonoids were found to exhibit an important immunomodulatory effect and could decrease irinotecan-induced toxic and genotoxic effects to normal cells without effecting irinotecan cytotoxicity in EAT cells.

Therapeutic effect of propolis and paclitaxel on hepatic phase I and II enzymes and marker enzymes in dimethylbenz(a)anthracene-induced breast cancer in female rats

Propolis, a natural beehive product has been known for centuries for a variety of beneficial traditional medicinal properties. The present study was conducted to ascertain the antineoplastic potential of propolis along with paclitaxel against experimental mammary carcinogenesis. Female Sprague Dawley rats at 55 days of age were treated with dimethylbenz(a)anthracene to induce breast cancer. Paclitaxel at a dose of 33 mg/kg body mass intraperitoneally and propolis 50 mg/kg body weight orally was administered to the experimental animals, immediately after the carcinogen treatment and continued until the termination of the study. At the end of the treatment activities of phase I and II xenobiotic metabolizing enzymes and liver marker enzymes were measured. A significant increase in carcinogen activating enzymes, cytochrome P(450), cytochrome b(5) and NADPH cytochrome C reductase with concomitant decrease in phase II enzymes, glutathione transferase and UDP-glucuronyl transferase were observed in animals with mammary cancer. Furthermore there was a significant decrease in alanine aminotransferase, aspartate aminotransferase with a sharp increase in alkaline phosphatase, acid phosphatase and 5' nucleotidase. Propolis treatment caused the activity of these enzymes return to almost normal control levels, indicating the protective effect of propolis against dimethyl benz(a) anthracene induced carcinogenesis. On the basis of the observed results propolis can be considered a promising chemotherapeutic agent and can be administered as an adjuvant with paclitaxel chemotherapy.