本研究根据赤羽病毒（AKAV）的S基因序列设计合成了引物, RT-PCR扩增得到目的基因片段并克隆到PGM-T载体得到质粒标准品。通过对荧光定量PCR反应条件的优化,建立了SYBR Green I荧光定量PCR检测AKAV的方法。该方法的检测敏感性达到926拷贝/25μL,并具有较好的重复性和特异性。本试验方法的建立对于加强进出口牛AKAV的检验检疫具有十分重要的意义。 相似文献
Seven new polyoxygenated steroids (1–7) were isolated together with seven known analogues (8–14) from the South China Sea soft coral, Sarcophyton sp. The structures of the new compounds were identified on the basis of extensive spectroscopic analysis and comparison with reported data. All the steroids are characterized with 3β,5α,6β-hydroxy moiety, displaying carbon skeletons of cholestane, ergostane, gorgostane and 23,24-dimethyl cholestane. In the in vitro bioassay, metabolites exhibited different levels of antimicrobial activity against bacterial species Escherichia coli and Bacillus megaterium, and fungal species Microbotryum violaceum and Septoria tritici. No inhibition was detected towards microalga Chlorella fusca. Preliminary structure-activity analysis suggests that the 11α-acetoxy group may increase both antibacterial and antifungal activities. The terminal-double bond and the cyclopropane moiety at the side chain may also contribute to the bioactivity. 相似文献
Mangrove-derived actinomycetes are promising sources of bioactive natural products. In this study, using homologous screening of the biosynthetic genes and anti-microorganism/tumor assaying, 163 strains of actinomycetes isolated from mangrove sediments were investigated for their potential to produce halogenated metabolites. The FADH2-dependent halogenase genes, identified in PCR-screening, were clustered in distinct clades in the phylogenetic analysis. The coexistence of either polyketide synthase (PKS) or nonribosomal peptide synthetase (NRPS) as the backbone synthetases in the strains harboring the halogenase indicated that these strains had the potential to produce structurally diversified antibiotics. As a validation, a new enduracidin producer, Streptomyces atrovirens MGR140, was identified and confirmed by gene disruption and HPLC analysis. Moreover, a putative ansamycin biosynthesis gene cluster was detected in Streptomyces albogriseolus MGR072. Our results highlight that combined genome mining is an efficient technique to tap promising sources of halogenated natural products synthesized by mangrove-derived actinomycetes. 相似文献
1. The objective of this study was to evaluate the effects of dietary supplementation with phytase transgenic corn (maize) (PTC) which has a phytase activity of 21 000 units (U) phytase per kg of maize on productive performance, egg quality, tibia bone quality and phosphorus (P) excretion in laying hens.
2. In the experiment, 1800 44-week-old Hy-line brown laying hens were divided into 5 groups with 6 replicates per group and 60 hens per replicate. The experiment lasted for 12 weeks. The layers in the control group (control) were given a basal diet with 0.36% non-phytate P (NPP), while the treatment groups received diets containing 360 U of exogenous phytase/kg with 0.26% NPP (EP) or 360 phytase U of PTC/kg diet with 0.26% (PTC1), 0.21% (PTC2) or 0.16% (PTC3) NPP.
3. The results showed that there was no significant difference in egg production, average daily feed intake, feed efficiency, rate of broken or soft-shell egg production or egg mass among the treatments. There was no significant difference in eggshell thickness or eggshell strength. On the other hand, no differences in any of the bone variables were found between treatments. The faecal P percentage content in EP, PTC1, PTC2 and PTC3 groups was significantly lower than the control group.
4. In summary, the PTC could be used in the feed of laying hens instead of EP to reduce P excretion without effecting production and bone mineralisation. 相似文献
