Loop-mediated isothermal amplification (LAMP) allows rapid amplification of nucleic acids under isothermal conditions. In this report, a 20-min LAMP amplification of the DPOL gene of infectious spleen and kidney necrosis virus (ISKNV) using a biotin-labeled primer was combined with lateral flow dipstick (LFD) chromatography for rapid and simple visual detection of ISKNV-specific amplicons. The LFD process involves a 5-min specific hybridization with an FITC-labeled DNA probe to confirm the presence of complement ISKNV amplicons that were biotinated in LAMP. The resulting DNA duplexes, consisting of labeled probes and amplicons, migrate along the LFD strip by chromatography for 5 min and are trapped at the test line and visualized by biotin labeling. The detection limit of ISKNV by LAMP-LFD was 10 copies. The results show that the LAMP-LFD method has the advantages of better sensitivity and speed and less dependence on equipment than the standard PCR for specifically detecting low levels of ISKNV DNA, and this can be useful in the field as a routine diagnostic tool.

Water pollution of heavy metals such as cadmium is a serious problem in China. Cadmium is toxic to cellular processes such as the transport and metabolism of iron. The nucleotide sequences of serum transferring (c-sTf) and hepcidin (c-Hep) genes from croceine croaker (Pseudosciaena crocea) were determined. The full-length cDNAs of c-sTf and c-Hep were 2,486 and 850 nt, respectively. After cadmium exposure (CdE), fish serum iron increased significantly and reached a high level at 24 h, after which it decreased and reached normal levels after 72 h. TIBC increased to a high level at 24 h and maintained that to the end of the experiment. Tf saturation increased to a high level at 24 h, then decreased and returned to normal after 72 h. Higher erythrocyte numbers in the blood were found after 24 h. c-sTf mRNA in fish liver significantly increased at 24 h and maintained to the end of the experiment. c-Hep mRNA expression significantly increased at 24 h and reached a high level at 48 h, then decreased to normal by 72 h. Therefore, it suggests that iron status was the signal for mRNA expression of hepcidin in liver, while erythrocytes changes in blood were the signals for that of sTf.

Natural occurrence of hexaploid loach Misgurnus anguillicaudatus detected in central China is reported here for the first time. The evidences from karyotyping, DNA content analysis and nuclear volume measurements were described to confirm the hexaploid nature of the identified individual.

In search for an easy, rapid and cost-effective method to determine the ploidy levels of diploid and tetraploid dojo loaches Misgurnus anguillicaudatus distributed naturally in China, direct (karyotyping) and indirect (flow cytometry, erythrocyte nuclear measurements and morphometric analysis) methods were compared. The results revealed that all techniques employed may be successfully used to determine the ploidy levels. It was discovered that karyotyping is cumbersome; flow cytometry is expensive whereas erythrocyte nuclear measurement requires a long time and intensive labour. On the other hand, the morphometric analysis method, especially the measurement of head length (HL), snout length (SL) and depth of caudal peduncle (CPD), is the simplest, with no damage to the fish and can be considered a practical alternative to other techniques. The discriminant function developed from the specimens, D = 7.539(HL ⁄ CPD)) 2.342(HL ⁄ SL))5.636, categorized an observation as a diploid if the discriminant analysis gave a positive score, while negative scores were categorized as tetraploids.