Characterization of three lamp genes from largemouth bass (Micropterus salmoides): molecular cloning, expression patterns, and their transcriptional levels in response to fast and refeeding strategy.

Lysosomes-associated membrane proteins (LAMPs), a family of glycosylated proteins and major constituents of the lysosomal membranes, play a dominant role in various cellular processes, including phagocytosis, autophagy and immunity in mammals. However, their roles in aquatic species remain poorly known. In the present study, three lamp genes were cloned and characterized from Micropterus salmoides. Subsequently, their transcriptional levels in response to different nutritional status were investigated. The full-length coding sequences of lamp1, lamp2 and lamp3 were 1251bp, 1224bp and 771bp, encoding 416, 407 and 256 amino acids, respectively. Multiple sequence alignment showed that LAMP1-3 were highly conserved among the different fish species, respectively. 3-D structure prediction, genomic survey, and phylogenetic analysis were further confirmed that these genes are widely existed in vertebrates. The mRNA expression of the three genes was ubiquitously expressed in all selected tissues, including liver, brain, gill, heart, muscle, spleen, kidney, stomach, adipose and intestine, lamp1 shows highly transcript levels in brain and muscle, lamp2 displays highly expression level in heart, muscle and spleen, but lamp3 shows highly transcript level in spleen, liver and kidney. To analyze the function of the three genes under starvation stress in largemouth bass, three experimental treatment groups (fasted group and refeeding group, control group) were established in the current study. The results indicated that the expression of lamp1 was significant induced after starvation, and then returned to normal levels after refeeding in the liver. The expression of lamp2 and lamp3 exhibited the same trend in the liver. In addition, in the spleen and the kidney, the transcript level of lamp1 and lamp2 was remarkably increased in the fasted treatment group and slightly decreased in the refed treatment group, respectively. Collectively, our findings suggest that three lamp genes may have differential function in the immune and energetic organism in largemouth bass, which is helpful in understanding roles of lamps in aquatic species.

Spatial and temporal variations of metal fractions in paddy soil flooding with acid mine drainage.

Environmental release of acid mine drainage (AMD) poses a potential threat to the environment and human health due to its high content of heavy metals. The impact of AMD flooding on unpolluted soil leads to serious pollution over time via a complex process, related to the geochemical behavior of toxic metals that so far has only been partially investigated. Here, a soil column study was conducted to investigate the migration of Cu and Cd fractions in unpolluted paddy soil following treatment with AMD collected from the Dabaoshan Mining area. Tessier's sequential extraction was performed to fractionate the metals at various depths over time. After 160 days of experimental flooding, the soil pH stabilized at 2.52 at a column depth of 5 cm. The fractions of Cu and Cd that were highly mobile increased significantly during AMD flooding. For Cd, the latter already occurred on day 67. At a depth of 20 cm, the total content of Cu maximally increased from initially 26.89 mg kg-1 to 696.96 mg kg-1 on day 160, while the content of Cd maximally increased from 0.22 mg kg-1 to 391.30 mg kg-1 on day 67. Reduced partition index analysis conformed that the mobility of both Cu and Cd significantly increased in contaminated soil during continuous AMD flooding. Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) identified a changed distribution of the elements in the soil, with Fe appearing to have aggregated. The correlation analysis between Cu and Cd in pore water and in different fractions in the soil's solid phase identified a dynamic distribution of these metals in certain geochemical components during their migration. The results of this study contribute to a scientific foundation to describe the geochemical behavior of heavy metals in soil subject to AMD flooding.

A highly sensitive and selective fluorescence biosensor for hepatitis C virus DNA detection based on δ-FeOOH and exonuclease III-assisted signal amplification.

Developing the high selectivity and sensitivity strategy for nucleic acid detection is crucial for early diagnosis and therapy of diseases. In this work, a novel low back-ground fluorescent sensor platform for the detection of nucleic acid has been developed based on δ-FeOOH nanosheets integrating with exonuclease III-assisted target-recycling signal amplification. Because of the strong binding ability between the single-strand DNA (ssDNA) and the δ-FeOOH nanosheets, the dye-labeled ssDNA probe would be quenched by δ-FeOOH nanosheets through fluorescence resonance energy transfer (FRET). By using magnetic separate properties of δ-FeOOH, the background signal was separated from the sensor system, and the low background sensor system was obtained. After adding the target DNA, a double-strand DNA complex (dsDNA) would be formed between the target DNA and dye-labeled ssDNA probe. Then, the dye-labeled ssDNA probe in the dsDNA complex would be stepwise hydrolyzed into short fragments from 3'-terminus by Exonuclease III, and the fluorescence signal was recovered due to the weak bind affinity between the short fragments and δ-FeOOH nanosheets. By using the fluorescence quenching ability of δ-FeOOH nanosheets and enzyme-assisted target-recycling signal amplification, this strategy could show an excellent selectivity toward hepatitis C virus DNA with a low detection limit of 10 pM. By simply changing the dye-labeled ssDNA probe sequence, this sensing platform can be developed as a universal approach for the simple, sensitive, and selective detection of different target DNA.

A high sensitivity background eliminated fluorescence sensing platform for hyaluronidase activity detection based on Si QDs/HA-δ-FeOOH nanoassembly.

Using fluorescent sensors for highly sensitive and selective detection of biomolecules is a very important strategy in clinical diagnoses as well as biomedical applications. But fluorescent sensors usually suffer from high background signal, which greatly hinders their detection sensitivity. In this work, a novel background-eliminated fluorescence assay for sensitive and selective detection of biomolecule has been developed by coupling feroxyhyte nanosheets (δ-FeOOH) with amino-functionalized silicon quantum dot (Si QDs). We select hyaluronidase (HAase) as the modal target to verify the concept. Si QDs/HA-δ-FeOOH nanoassembly was fabricated by self-assembly of positive Si QDs together with negative HA-δ-FeOOH through electrostatic adsorption. By the introduction of hyaluronidase, the nanoassembly exhibits obviously fluorescence signal recovered. Research suggests that under optimized conditions, this strategy exhibits a good linear response to the concentration of HAase in the range of 0.1 to 12 ng/mL. The detection limit for HAase was 0.02 ng/mL (based on 3σ/S), which was three-order lower than most of the reported fluorescence biosensors for the detection of HAase. Furthermore, this new biosensor has already been applied in the study of urine samples, and the detection results were consistent with those obtained by the clinical tests.