The tricarboxylic acid cycle is inhibited under acute stress from carbonate alkalinity in the gills of Eriocheir sinensis.

Owing to population growth and environmental pollution, freshwater aquaculture has been rapidly shrinking in recent years. Aquaculture in saline-alkaline waters is a crucial strategy to meet the increasing demand for aquatic products. The Chinese mitten crab is an important economic food in China, but the molecular mechanism by which it tolerates carbonate alkalinity (CA) in water remains unclear. Here, we found that enzyme activities of the tricarboxylic acid (TCA) cycle in the gills, such as citrate synthase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and malate dehydrogenase, were markedly reduced under CA stress induced by 40 mM NaHCO3. Secondly, the TCA cycle in the gills is inhibited under acute CA stress, according to proteomic and metabolomic analyses. The expressions of six enzymes, namely aconitate hydratase, isocitrate dehydrogenase, 2-oxoglutarate dehydrogenase, dihydrolipoyl dehydrogenase, succinate-CoA ligase, and malate dehydrogenase, were downregulated, resulting in the accumulation of phosphoenolpyruvic acid, citric acid, cis-aconitate, and α-ketoglutaric acid. Finally, we testified that if the TCA cycle is disturbed by malonate, the survival rate increases in CA water. To our knowledge, this is the first study to show that the TCA cycle in the gills is inhibited under CA stress. Overall, the results provide new insights into the molecular mechanism of tolerance to saline-alkaline water in crabs, which helped us expand the area for freshwater aquaculture and comprehensively understand the physiological characteristics of crab migration.

Glutamate-pantothenate pathway promotes antibiotic resistance of Edwardsiella tarda.

Although cellular metabolic states have been shown to modulate bacterial susceptibility to antibiotics, the interaction between glutamate (Glu) and chloramphenicol (CAP) resistance remains unclear because of the specificity of antibiotics and bacteria. We found that the level of Glu was upregulated in the CAP-resistant strain of Edwardsiella tarda according to a comparative metabolomics approach based on LC-MS/MS. Furthermore, we verified that exogenous metabolites related to Glu, the tricarboxylic acid (TCA) cycle, and glutathione (GSH) metabolism could promote CAP resistance in survival assays. If GSH metabolism or the TCA cycle is inhibited by L-buthionine sulfoximine or propanedioic acid, the promotion of CAP resistance by Glu in the corresponding pathway disappears. According to metabolomic analysis, exogenous Glu could change pantothenate metabolism, affecting GSH biosynthesis and the TCA cycle. These results showed that the glutamate-pantothenate pathway could promote CAP resistance by being involved in the synthesis of GSH, entering the TCA cycle by direct deamination, or indirectly affecting the metabolism of the two pathways by pantothenate. These results extend our knowledge of the effect of Glu on antibiotic resistance and suggest that the potential effect, which may aggravate antibiotic resistance, should be considered before Glu and GSH administration in the clinic.

Progress in the application of Enterococcus faecium in animal husbandry.

As a probiotic, enterococcus faecium (E. faecium) has the characteristics of high temperature resistance, gastric acid resistance, bile salt resistance, etc. It can also effectively improve animal performance and immunity and improve the animal's intestinal environment, so in recent years it has been more widely used in the livestock industry. However, due to the improper use of antibiotics and the growing environmental stress of strains, the drug resistance of enterococcus faecium has become more and more serious, and because some enterococcus faecium carry virulence genes, leading to the emergence of pathogenic strains, its safety issues have been widely concerned. This paper focuses on the biological characteristics of enterococcus faecium, the application of this bacterium in animal husbandry and the safety issues in its use, with a view to providing a reference for the application of enterococcus faecium in the development of animal husbandry.

Transcriptome analysis in the spleen of Northern Snakehead (Channa argus) challenged with Nocardia seriolae.

Northern snakehead (Channa argus) is an indigenous fish species and is one of popularly cultured snakeheads in China and other Asian countries. Unfortunately, Nocardia seriolae infections have caused considerable losses in the snakehead aquaculture industry. However, the infectivity and the immune response induced by N. seriolae in snakehead are unclear. In order to better understand the immune response of Northern snakehead in a series of time points after N. seriolae challenge, we conducted the transcriptomic comparison in snakehead spleen at 48, 96, and 144 h after the challenge of N. seriola against their control counterparts. Gene annotation and pathway analysis of differentially expressed genes (DEGs) were carried out to understand the functions of the DEGs. Additionally, protein-protein interaction networks were conducted to obtain the interaction relationships of immune-related DEGs. These results revealed the expression changes of multiple DEGs and signaling pathways involved in immunity during N. seriolae infection, which will facilitate our comprehensive understanding of the mechanisms involved in the immune response to bacterial infection in the northern snakehead.

Metabolites in the TCA Cycle Promote Resistance to Chloramphenicol of Edwardsiella tarda.

Antibiotic-resistant bacteria are a serious threat to human and animal health. Metabolite-enabled eradication of drug-resistant pathogens is an attractive strategy, and metabolite adjuvants, such as fumarate, are used for restoring the bactericidal ability of antibiotics. However, we show that metabolites in the TCA cycle increase the viability of Edwardsiella tarda against chloramphenicol (CAP), based on the survival assay of differential metabolites identified by LC-MS/MS. Furthermore, NADPH promotes CAP resistance in the CAP-resistant strain, while oxidants restore the bactericidal ability. Finally, we show that the intracellular redox state determines the sensitivity to CAP, and the total antioxidative capacity is decreased significantly in the antibiotic-resistant strain. Considering that the metabolites promote CAP resistance, metabolite adjuvants should be applied very cautiously. Overall, our research expands on the knowledge that the redox state is related to the bactericidal ability of CAP.

The complete mitochondrial genome of two different colour Luciobarbus capito (Cypriniformes, Cyprinidae).

We sequenced and characterized the complete mitochondrial genome from normal colour (grey black) and mutant colour (orangey red) of Luciobarbus capito. Both mitogenomes contained the typical complement of 13 protein-coding genes, 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs), and a non-coding control region. They share the same gene arrangement pattern that was identical with most vertebrates. The entire mitochondrial DNA molecule of grey black L. capito was 16603-bp long, while the complete mtDNA molecule of orangey red L. capito was 16607-bp long.

The complete mitochondrial genome of golden yellow snakehead fish, Channa argus.

We sequenced and characterized the complete mitochondrial genome of golden yellow snakehead fish, Channa argus. The mitogenomes contained the typical complement of 13 protein-coding genes, 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs), and a non-coding control region. They share the same gene arrangement pattern that was identical with most vertebrates. The entire mitochondrial DNA molecule of golden yellow snakehead fish was 16,558 bp long. All information reported in this article will be a useful source of sequence information for general molecular and evolutionary studies of the family Channidae.

Apoptosis of non-tumor cells contributes to increased serum cytochrome c level in a neuroblastoma xenograft model.

BACKGROUND: Neuroblastoma (NB) is one of the most common malignant solid tumors of childhood. It is still not clear whether the apoptosis of tumor cells or the non-tumor cells contributes to the increase of concentration of cytochrome c (Cyt c) in the serum of the cancer patients. The aim of this research was to identify the source of the Cyt c in the serum when the tumor grows up by subcutaneous inoculation of human NB cells into nude mice. METHODS: We subcutaneously inoculated human NB cells (KP-N-NS) into nude mice and collected the sera of tumor-bearing mice (n = 14) and control mice (n = 25) 4 weeks later in order to screen for and identify differentially expressed proteins in the serum. Differentially expressed proteins in the serum were screened by surface-enhanced laser desorption/ionization-time-of-flight (SELDI-TOF) mass spectrometry. RESULTS: The relative intensity of a protein having a mass-to-charge ratio (m/z) of 11 609 was 3338.37 ± 3410.85 in the tumor group and 59.84 ± 40.74 in the control group, indicating that the expression level of this protein in the tumor group was 55.8 times higher than that in the control group. Serum proteins were separated and purified by high-performance liquid chromatography (HPLC). Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was performed to produce peptide mass fingerprints (PMFs). Spectrum analysis and a database search revealed that the highly expressed protein (m/z = 11 605.4) from the serum of tumor-bearing mice was the mouse Cyt c. CONCLUSIONS: Increased concentration of Cyt c in the serum of tumor-bearing nude mice might be partially attributed to the secretion of this protein by non-tumor cells.

Multi-dimensional transition-metal coordination polymers with 5-nitro-1,2,3-benzenetricarboxylic acid exhibiting ferro-/antiferromagnetic interactions.

Six transition metal coordination polymers, [Cu(3)(nbta)(2)(bipy)(2)(H(2)O)(2)] x 2 H(2)O (1), [Cu(3)(nbta)(2)(bpp)(2)(H(2)O)(2)] x 2 H(2)O (2), [Co(3)(nbta)(2)(bipy)(3)(H(2)O)(2)] x 2 H(2)O (3), [Co(3)(nbta)(2)(bpp)(2)(H(2)O)(2)] (4), [Ni(2)(Hnbta)(2)(bipy)(2)(H(2)O)(2)] (5) and [Ni(3)(nbta)(2)(bpa)(3)(H(2)O)(2)] x 2 H(2)O (6) (H(3)nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, bipy = 4,4'-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane), have been hydrothermally synthesized by the reactions of Cu(II), Co(II) and Ni(II) salts with H(3)nbta in the presence of dipyridyl-type co-ligands, respectively. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and TG analyses. Compounds 1-4 and 6 exhibit 3D pillared-layer structures while compound 5 has a 2D layer. The nbta(3-) ligands in the 2D carboxylate layer motifs of 1-4 and 6 connect transition metal ions in different coordination modes, and the dipyridyl-type co-ligands in compounds 1-4 and 6 serve as the pillar between the 2D layers, creating 3D open frameworks. From a topologic point of view, complex 1, 2 and 4 present 4-connected 3D coordination frameworks with the topologies of (4(2) x 6(2) x 8(2)) (6(2) x 7(2) x 8(2)) (4(2) x 6(2) x 7 x 8), (6(4) x 8(2)) (4(2) x 6(4)) (4(2) x 6(4)) and (4 x 6(4) x 8)(4(4) x 6(2))(4(3) x 6(3)) respectively. Complex 3 shows a (4,5)-connected 3D network with (4(2) x 6(7) x 8)(6(4) x 8(2))(4(2) x 6(4)) topology. Whereas the structure of 5 is a 2D (4,4) net due to the partially deprotonated H(3)nbta ligand existed. Complex 6 features a 3D (4,5)-connected framework with (4 x 6(8) x 8) (6(5) x 8) (4 x 6(5)) topology, also exhibiting the intriguing helical motif. The variable-temperature magnetic susceptibility studies reveal antiferromagnetic interactions between Cu(II) or Co(II) ions in 1, 2, 3, 4 and ferromagnetic interactions between Ni(II) ions for 5 and 6, respectively.