Combined effects of copper and cadmium exposure on ovarian function and structure in Nile Tilapia (Oreochromis niloticus).

With the rapid development of industrialization and urbanization, the issue of copper (Cu) and cadmium (Cd) pollution in aquatic ecosystems has become increasingly severe, posing threats to the ovarian tissue and reproductive capacity of aquatic organisms. However, the combined effects of Cu and Cd on the ovarian development of fish and other aquatic species remain unclear. In this study, female Nile tilapia (Oreochromis niloticus) were individually or co-exposed to Cu and/or Cd in water. Ovarian and serum samples were collected at 15, 30, 60, 90, and 120 days, and the bioaccumulation, ovarian development, and hormone secretion were analyzed. Results showed that both single and combined exposure significantly reduced the gonadosomatic index and serum hormone levels, upregulated estrogen receptor (er) and progesterone receptor (pr) gene transcription levels, and markedly affected ovarian metabolite levels. Combined exposure led to more adverse effects than single exposure. The data demonstrate that the Cu and Cd exposure can impair ovarian function and structure, with more pronounced adverse effects under Cu and Cd co-exposure. The Cu and Cd affect the metabolic pathways of nucleotides and amino acids, leading to ovarian damage. This study highlights the importance of considering combined toxicant exposure in aquatic toxicology research and provides insights into the potential mechanisms underlying heavy metal-induced reproductive toxicity in fish.

The complete mitochondrial genome of Calappa bilineata: The first representative from the family Calappidae and its phylogenetic position within Brachyura.

In this study, we determined the complete mitogenome sequence of Calappa bilineata, which is the first mitogenome of Calappidae up to now. The total length is 15,606 bp and includes 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs and one control region. The genome composition is highly A + T biased (68.7%), and exhibits a negative AT-skew (-0.010) and GC-skew (-0.267). As with other invertebrate mitogenomes, the PCGs start with the standard ATN and stop with the standard TAN codons or incomplete T. Phylogenetic analysis showed that C. bilineata was most closely related to Matuta planipes (Matutidae), and these two species formed a sister clade, constituting a Calappoidea group and forming a sister clade with part of Eriphioidea. The existence of the polyphyletic families raised doubts over the traditional classification system. These results will help to better understand the features of the C. bilineata mitogenome and lay foundation for further evolutionary relationships within Brachyura.

Development of a Liquid Chip Technique to Simultaneously Detect Spring Viremia of Carp Virus, Infectious Hematopoietic Necrosis Virus, and Viral Hemorrhagic Septicemia of Salmonids.

A liquid chip technique was developed to detect spring viremia of carp virus (SVCV), infectious hematopoietic necrosis virus (IHNV), and viral hemorrhagic septicemia virus (VHSV) of salmonids simultaneously. Sequences of the G gene of SVCV, N gene of IHNV, and G gene of VHSV were used to design SVCV-, IHNV-, and VHSV-specific primers, which were labeled with biotin and subjected to amination modification. They were then coupled with fluorescence-coded microspheres and used for hybridization with reverse-transcription PCR products of SVCV, IHNV, and VHSV. A BD FACSArray was used to detect fluorescence signal in the reaction system. This assay system had a high sensitivity to SVCV, VHSV, and IHNV, with LODs of 10, 10, and 100 pg/µL, respectively. Moreover, the assay was specific for the detection of SVCV, IHNV, and VHSV and was not susceptible to cross-detection of other viruses, including pike fry rhabdovirus, hirame rhabdovirus, infectious pancreatic necrosis virus, viral nervous necrosis virus, yellowtail ascites virus, grass carp reovirus, red sea bream iridovirus, and koi herpesvirus. The liquid chip assay technique established in this study provides a novel, convenient, and rapid approach for the detection of SVCV, IHNV, and VHSV.