Aiguo Huang

Toxicological effects of multi-walled carbon nanotubes on Saccharomyces cerevisiae: The uptake kinetics and mechanisms and the toxic responses.

Using Saccharomyces cerevisiae as an experimental model, the potential toxicological effects of oxidized multi-walled carbon nanotubes (MWCNTs) were investigated following exposure to 0-600mg/L for 24h. Results indicated that MWCNTs (>100mg/L) had adverse effects on the cell proliferation. MWCNTs were clearly visible in lysosome, vacuole, endosome, mitochondria, multivesicular body and localization in the perinuclear region. The uptake kinetics data demonstrated that the maximum MWCNTs content (209.61mg/g) was reached at 3h, and a steady state was reached after 18h. Based on the combined results of transmission electron microscope, endocytosis inhibition experiments and endocytosis-related genes (END3, END6, Sla2 and Rsp5) expression analysis, we elucidated MWCNTs uptake mechanism: (i) via a direct penetration of single MWCNTs; (ii) via endocytosis of single MWCNTs; and (iii) via endocytosis of MWCNTs aggregates. The percentage of apoptosis was significant increased at 600mg/L. The decrease of mitochondrial transmembrane potential and the leakage of cytochrome c shown dose-dependent manners. Interestingly, there was no significant increase of reactive oxygen species (ROS). The apoptosis-related genes (SOD1, SOD2, Yca1, Nma111 and Nuc1) were significant changed. These results obtained in our study demonstrated that oxidized MWCNTs induce Saccharomyces cerevisiae apoptosis via mitochondrial impairment pathway.

In vitro and in vivo assessment of the effect of antiprotozoal compounds isolated from Psoralea corylifolia against Ichthyophthirius multifiliis in fish.

Highlights • Two antiprotozoal compounds from P. corylifolia were isolated and identified.• In vitro antiprotozoal efficacies of isopsoralen and psoralidin were evaluated.• Psoralidin had a detrimental effect on I. multifiliis trophont in situ.• The action mechanism against I. multifiliis trophont in situ was investigated.

The oxidative stress response of myclobutanil and cyproconazole on Tetrahymena thermophila.

Using Tetrahymena thermophila as experimental models, the oxidative stress of triazole fungicides myclobutanil (MYC) and cyproconazole (CYP) was investigated. Results showed that 24-h EC50 values for MYC and CYP were 16.67 (13.37-19.65) and 20.44 (18.85-21.96) mg/L, respectively; 48-h EC50 values for MYC and CYP were 14.31 (13.13-15.42) and 18.76 (17.09-20.31) mg/L, respectively. Reactive oxygen species was significantly induced and cytotoxicity was caused by MYC and CYP by increasing propidium iodide (PI) fluorescence. Damage of regular wrinkles and appearing of small holes on the cell surface were observed by SEM. Furthermore, MYC and CYP also caused notable changes in enzyme activities and mRNA levels. Overall, the present study points out that MYC and CYP lead to oxidative stress on T. thermophila. The information presented in this study will provide insights into the mechanism of triazoles-induced oxidative stress on T. thermophila.

Morphometric and molecular characterization of Dactylogyrus vastator and D. intermedius in goldfish (Carassius auratus)

Goldfish is known to be parasitized by at least seven species of Dactylogyrus and considered as one of the most common hosts. Dactylogyrus vastator and Dactylogyrus intermedius are the dominant species living on the gills of goldfish. However, little information on morphometric characterization is available, which easily causes misidentification. The purpose of this study is to provide comprehensive morphometric and molecular characterization of D. vastator and D. intermedius collected form a fish farm in Henan, China. The characterization was presented based on the high-resolution images and standard molecular markers (18S ribosomal DNA subunit and the internal transcribed spacer region), as well as a total of 10 point-to-point morphometrics characters. In addition, a detailed comparison of morphometric and phylogenetic characterization in D. vastator versus D. intermedius was performed. The results demonstrated that all parameters measured differed significantly between these two species of Dactylogyrus, whereas molecular comparison showed subtle differences between them in nucleotide divergence and genetic distances. These findings suggested that these two species of Dactylogyrus can be distinguished more easily based on morphometric measurements than molecular data for 18S ribosomal DNA + internal transcribed spacer region (ITS-1).

The first report of Dactylogyrus formosus Kulwiec, 1927 (Monogenea: Dactylogyridae) from goldfish (Carassius auratus) in central China

Dactylogyrus formosus Kulwiec, 1927 (Monogenea: Dactylogyridae), widely distributed across Eurasia, is considered as one of the most frequently encountered ectoparasites of goldfish (Carassius auratus). In the present study, D. formosus on gills of cultured goldfish was reported in central China for the first time, using the methods of morphological characters and molecular markers. It was characterized by “Anchoratoid–Wegeneri” type anchor with elongate inner and unobvious outer root. The morphology of the opisthaptoral hard parts of D. formosus superficially resembles species of D. arcuatus Yamaguti, 1942 parasitized crucian carp, using light and scanning electron microscopy. However, the anchor total length of D. arcuatus (range 90–102) is almost double the size of D. formosus (range 43.7–57.1) which allows for their rapid discrimination from each other; on the other hand, the two species also can be easily separated by the shape of the male copulatory organ. The morphological description of D. formosus is supplemented with phylogenetic analysis of a reference DNA sequence spanning 18S rDNA and ITS1. What is more, this study also redescribes comprehensively D. formosus, providing for the first time a full ten point-to-point morphometric measurements of the hard parts, and importantly, a photographic record of the armature of the haptor and the male copulatory organ.

Enhanced protective immunity against spring viremia of carp virus infection can be induced by recombinant subunit vaccine conjugated to single-walled carbon nanotubes

As a successful prevention strategy for controlling the highly contagious and pathogenic disease of spring viremia of carp (SVC), DNA vaccines reported in recent years could trigger protective responses against SVC with the means of injection. However, there remains many concerns and uncertainties related to DNA vaccination as well as injection is labor intensive, costly and not suitable to vaccinate large numbers of fish. Therefore, more efficient and safe prophylactic measures should be urgently investigated. In this research, single-walled carbon nanotubes (SWCNTs) as the candidate SWCNTs-pET32a-G subunit vaccine carrier were administrated via bath (1, 5, 10, 20, 40 mg L-1) or injection (1, 4, 8, 12, 20 μg) in common carp juvenile, and the different immune treatments to induce immunoprotective effect were analyzed. The results showed that SWCNTs-pET32a-G could enter fish body after immersion for 10 h, furthermore, compared to control groups, antibody levels, the non-specific immune parameters (complement activity, superoxide dismutase activity and alkaline phosphatase activity), and immune-related genes (especially the TNF-α and IFNg2b) in vaccinated groups were significantly enhanced in fish immunized with SWCNTs-subunit vaccine. In addition, as a promising carrier, SWCNTs can increase the immune protective effect of naked subunit vaccine by ca. 16% in bath immunization group and by ca. 23% in injection group. This study suggests that SWCNTs-vaccine may represent a potentially efficient immersion vaccine against viral pathogens of fish in the future.

Magnolol protects Ctenopharyngodon idella kidney cells from apoptosis induced by grass carp reovirus

ABSTRACT Many natural products from medicinal plants are small molecular weight compounds with enormous structural diversity and show various biological activities. Magnolol is a biphenol compound rich in the stem bark of Magnolia officinalis Rehd et Wils., and is able to suppress viral replication in GCRV‐infected grass carp (Ctenopharyngodon idella) kidney (CIK) cells in the previous study. In this study, in vivo studies demonstrated that magnolol was efficient to restrain the replication of GCRV and repair the low level of superoxide dismutase and total antioxidant capacity in serum at the non‐toxic concentration in vivo. Furthermore, magnolol inhibited CIK cell apoptosis induced by GCRV and kept the normal cellular morphological structure, reflecting in the protection of CIK cells from cell swelling, the formation of apoptotic bodies, the disappearance of cellular morphology and nuclear fragmentation. Reverse transcript quantitative polymerase chain reaction (RT‐qPCR) showed that magnolol facilitated the expression of apoptosis‐inhibiting gene bcl‐2, while suppressed the expression of apoptosis‐promoting gene bax in GCRV‐infected cells. Besides, RT‐qPCR and enzyme activity assays proved that magnolol suppressed the expression of caspase 3, caspase 8 and caspase 9. Moreover, interactions between magnolol and proteins were predicted by using the STITCH program, which revealed that ten proteins including caspase 3, were involved in the apoptosis pathway, p53 signaling pathway, mitogen‐activated protein kinase (MAPK) signaling pathway and toll‐like receptor signaling pathway. Further assays were performed to test the effect of magnolol on apoptosis pathway, which showed that magnolol dramatically inhibited the activity of caspase 3 rather than those of caspase 8 and caspase 9. Collectively, the present study revealed that magnolol heightened the resistance of grass carp against GCRV infection and refrained GCRV‐induced apoptosis, which may be attributed to the direct interaction of magnolol with caspase 3. The present results make a contribution to understanding the mechanisms by which small‐molecule drugs possess antiviral activities, and lay a foundation for the development of broad‐spectrum antiviral compounds in aquaculture industry. HIGHLIGHTSMagnolol suppressed GCRV replication and enhanced antioxidant capacity in vivo.Magnolol inhibited GCRV‐induced apoptosis and kept the normal cellular morphological structure.The potential interaction of magnolol with caspase 3 hampered GCRV‐induced apoptosis.