Signal transducer and activator of transcription 3 (STAT3) signaling is constantly activated in human melanoma, and promotes melanoma metastasis. The dietary flavonoid apigenin is a bioactive compound that possesses low toxicity and exerts anti-metastatic activity in melanoma. However, the anti-metastasis mechanism of apigenin has not been fully elucidated. In the present study, we showed that apigenin suppressed murine melanoma B16F10 cell lung metastasis in mice, and inhibited cell migration and invasion in human and murine melanoma cells. Further study indicated that apigenin effectively suppressed STAT3 phosphorylation, decreased STAT3 nuclear localization and inhibited STAT3 transcriptional activity. Apigenin also down-regulated STAT3 target genes MMP-2, MMP-9, VEGF and Twist1, which are involved in cell migration and invasion. More importantly, overexpression of STAT3 or Twist1 partially reversed apigenin-impaired cell migration and invasion. Our data not only reveal a novel anti-metastasis mechanism of apigenin but also support the notion that STAT3 is an attractive and promising target for melanoma treatment.
The toxicity of permethrin to different life stages of Culex quinquefasciatus (Say) was examined in three field insecticide resistant strains, HAmCq(G0), MAmCq(G0), and BAmCq(G0); two permethrin selected strains, HAmCq(G8) and MAmCq(G6); and a laboratory susceptible strain, S-Lab. The levels of tolerance to permethrin differed among the developmental stages of Culex mosquito larvae with an ascending order from first to fourth instar. A developmentally regulated pattern of permethrin resistance in Culex mosquito larvae was identified, once again increasing from first to fourth instar. Adult mosquitoes had relatively lower levels of resistance in general compared with their larval stages, suggesting that different mechanisms may be involved in the response to insecticide selection pressure between larvae and adults. Inheritance of resistance to permethrin was examined using reciprocal crosses between resistant HAmCq(G8) and susceptible S-Lab strains; the resulting logarithm concentration-probit response curves for reciprocal F1 lines were similar to those for the susceptible strain, with degree of dominance values of -0.2 to -0.3, suggesting that the inheritance of permethrin resistance in Cx. quinquefasciatus is incompletely recessive. No significant difference was found in the values of LC50 and the slope of the log concentration-probit lines between reciprocal F1 lines, indicating that the resistance to permethrin was inherited autosomally. Both chi2 goodness-of-fit test and log concentration-probit line analysis on responses of backcross and self-bred progeny to permethrin indicated that permethrin resistance in the HAmCq(G8) strain did not follow a monogenic gene inheritance model, revealing that permethrin resistance in Cx. quinquefasciatus is controlled by more than one gene.
The prevalence of coccidial infections in dairy cattle was examined in Shanghai from November 2010 to March 2011. In total, 626 fecal samples from 24 dairy farms were examined; oocysts were identified to the species level based on morphological features. All herds were infected with Eimeria species. The overall prevalence of coccidia was 47.1%, with the highest prevalence in <4-mo-old calves (51.8%) and the lowest in >12-mo-old cattle (27.0%). The number of oocysts per gram of feces was significantly higher in young calves than in weaners and adults. Ten species of Eimeria were identified, among which Eimeria ellipsoidalis, Eimeria bovis, Eimeria zuernii, and Eimeria alabamensis were the predominant species. Concurrent infection with 2-8 species was common.
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