Heavy metals are a group of heterogeneous elements with diverse functions and chemical properties, the environmental pollution of which has become a major global concern due to their persistence and toxicity. Cadmium (Cd), a non-essential heavy metal, is known for its high toxicity even at low concentrations and its tendency to bioaccumulate in the tissues of plants and animals. In this study, the toxic effects of Cd on Helicoverpa armigera (Hübner) embryonic cell cultures were investigated using TC-100 culture medium. Embryonic cells were exposed to Cd at concentrations of 97.7, 152.5, 205.4, 303.2, and 400.8 μmol/L for 24 hours. Lethal concentration values (LC₁₀, LC₃₀, and LC₅₀) were determined as 43.516, 105.910, and 196.100 μmol/L, respectively. To further explore the sublethal and lethal effects of Cd, enzymatic responses were analyzed at LC₃₀ and LC₅₀ exposure levels after 24 h. Antioxidant enzymes, including peroxidase (POX), superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (GPDH), were significantly enhanced in Cd-treated cells compared to controls. Additionally, the activities of detoxification enzymes such as glutathione S-transferase (GST) and cytochrome P450 monooxygenase (P450) were notably increased. In contrast, general esterase activity, assessed using α- and β-naphthyl acetate substrates, was markedly reduced following Cd exposure. These findings suggest that Cd, even at sublethal concentrations, disrupts cellular homeostasis and alters key enzymatic defense mechanisms in embryonic cells of H. armigera. This study highlights the toxicological risks posed by Cd contamination in ecosystems and its potential threat to insect development at the cellular level
Transient receptor potential ankyrin subtype 1 (TRPA1) is a nonselective cation channel involved in intracellular Ca²⁺ regulation and temperature sensing. In this study, we investigated the involvement of PyTRPA1-like in regulating UPR and apoptosis in haemocytes of the Yesso scallop Patinopecten yessoensis under low temperature stress (4 °C). The mRNA expression of PyTRPA1-like significantly increased at 1 h after treatment (p < 0.05), followed by elevated intracellular Ca²⁺ levels at 3 h (p < 0.05). Low temperature also significantly upregulated the mRNA expression of key UPR-related genes, including PyGRP78, PyIRE1, PyATF6β and PyPERK, while apoptosis-related genes PyCaspase-3 and PyBcl-2 showed time-dependent changes. Correspondingly, Caspase-3 activity and haemocyte apoptosis were significantly increased (p < 0.05). The combined treatment with the TRPA1 antagonist HC-030031 and low temperature significantly elevated intracellular Ca²⁺ levels, mRNA expression levels of PyBcl-2 and PyGRP78, Caspase-3 activity and apoptotic rate (p < 0.05), while significantly reducing PyIRE1 and PyPERK mRNA expression (p < 0.05). These findings suggest that PyTRPA1-like contributes to calcium influx and UPR activation under low temperature stress. Inhibition of PyTRPA1-like may induce compensatory calcium dysregulation and promote apoptosis partially independent of canonical UPR signaling
Litopenaeus vannamei is one of the most economically valuable aquaculture species. In recent years, the shrimp industry has experienced considerable economic losses due to various diseases such as acute hepatopancreatic necrosis disease (AHPND). AHPND is a disease caused by certain strain of Vibrio parahaemolyticus carrying a specific plasmid pVA1. The pVA1 plasmid contains the pirA and pirB genes, which encode the main virulence factors of AHPND. In light of the dearth of effective treatment options, the development of expeditious, precise, and effective methodologies for detecting AHPND pathogens is imperative to prevent the onset of disease in shrimp farming. However, current nucleic acid based and antibody-based detection methods sometimes produce false positive results, affecting the reliability of diagnosis. This study aims to make a comparison of the content of the pirA and pirB virulence factors at the DNA, RNA, and protein levels in order to investigate whether there is a corresponding relationship between the pathogenic factors of AHPND at the nucleic acid and protein levels, which will provide a foundation for the selection of pathogen detection methods for shrimp. At the mRNA level, the expression level of pirA is significantly higher than that of pirB. Conversely, at the protein level, the expression level of PirB protein is much higher than that of PirA protein, indicating that the results of the two different detection methods are contradictory. Therefore, relying solely on nucleic acid or protein testing may not accurately assess whether shrimp are diseased. In the future, a combined nucleic acid and protein testing strategy could be implemented to enhance diagnostic accuracy and ensure the sustainable development of the shrimp farming industry.
Penaeus vannamei is an important aquaculture species, but disease outbreaks posed a serious threat to the sustainable development of shrimp farming. In recent years, a fatal disease known as translucent post-larvae disease (TPD) has emerged in many farms, characterized by the vacuolization of the hepatopancreas and the pallor or colorlessness of the intestine. In this study, we obtained a strain of Vibrio parahaemolyticus, named H1, that could cause TPD in both juvenile and adult shrimps. V. parahaemolyticus H1 could cause gradual atrophy of the hepatopancreas, deepening of the intracellular material color, and eventually complete vacuolization. Antibiotic susceptibility tests revealed that V. parahaemolyticus H1 was resistant to chloramphenicol, ceftriaxone, and sulfamethoxazole trimethoprim, but exhibited resistance to tetracycline. The 2b-RAD-M analysis showed that V. parahaemolyticus H1 could disrupt the shrimp intestinal microbiota and lead to a loss of resistance to environmental bacteria. These results identified a pathogenic V. parahaemolyticus causing TPD from P. vannamei.
The suppression of malaria parasites in the presence of an existing microsporidian infection of Vavraia culicis, was examined using fluorescent Plasmodium berghei. Younger hosts infected with V. culicis had a greater suppressive effect on the subsequent development of P. berghei than older infected hosts. This effect was density dependant on the numbers of microsporidian spores present, consequently it was also dependant on the age at which mosquitoes were infected with microsporidia, as larvae infected later harboured comparatively fewer V. culicis spores. The timing of primary and secondary infections of larval and adult mosquitoes (host age) with different parasites affects parasite development and hence disease outcomes. The use of green, fluorescent P. berghei enabled easier and rapid visualisation and separation of malaria oocysts from V. culicis spores. Different degrees of melanisation of V. culicis spores were seen in a number of hosts and merits further investigation.
