The present study investigated the effects of varying protein source combinations and feeding strategies on the growth,health and organoleptic quality of the large yellow croaker(Larimichthys crocea).Three iso-nitroge...The present study investigated the effects of varying protein source combinations and feeding strategies on the growth,health and organoleptic quality of the large yellow croaker(Larimichthys crocea).Three iso-nitrogenous and iso-lipidic diets were formulated.The control diet was made with 62%fish meal(FM).The other two experimental diets were formulated by replacing 45%FM with 22.5%mealworm(TM)and 22.5%cottonseed protein concentrate(CPC),or with 22.5%TM and 22.5%Clostridium autoethanogenum protein(CAP),respectively.The three kinds of diet were named as A1,A2 and A3,respectively.Five groups of large yellow croaker were fed with two different strategies:the first three groups were continuously fed with A1,A2 and A3 diets,respectively.The fourth group was alternately fed with A1 and A2 diet every 5 days.The fifth group was alternately fed with A1 and A3diet every 5 days.The five groups were named D1,D2,D3,D1-2 and D1-3,respectively.Results showed that D2 and D3 groups exhibited significantly lower weight gain rate(WGR)and higher feed conversion ratios(FCR)compared to the D1 group.The D1-2 and D1-3 groups exhibited improved WGR and significantly reduced FCR compared to the D2 and D3 groups.The A2 and A3 diets significantly suppressed digestive enzymes'activities compared to A1,whereas alternate-feeding groups significantly enhanced the enzyme activities.Compared to the D1 group,D2 and D3 groups significantly downregulated mRNA expression levels of intestinal antiinflammatory cytokines and upregulated the expression of pro-inflammatory mediators.The anti-inflammatory abilities in the D1-2and D1-3 groups were significantly higher than those in the D2 and D3 groups.Additionally,diets containing TM+CAP and TM+CPC protein sources enhanced ventral redness and yellowness indices.Considering the growth,digestion,immunity and organoleptic quality of large yellow croaker,it is recommended to replace up to 45%of FM with TM+CPC and use an alternate-feeding strategy.展开更多
Salmonella gallinarum has shown multiple drug resistance(MDR),especially high level fluoroquinolone(FQ)resistance in recent years.To determine whether the active efflux system was responsible for high-level FQ resista...Salmonella gallinarum has shown multiple drug resistance(MDR),especially high level fluoroquinolone(FQ)resistance in recent years.To determine whether the active efflux system was responsible for high-level FQ resistance,this research studied AcrAB efflux pump in Salmonella gallinarum on molecular level.The resistant strains were induced by standard strain C79-13 with ciprofloxacin in vitro.With carbonylcyanide-p-chlorophenyl hydrazone(CCCP)as an energy inhibitor,efflux inhibition test initially showed the potential impact of efflux pump on drug resistance.Sequence analysis of acrA gene indicated that gene mutation of AcrAB efflux pump was not definitely associated with MDR and drug resistance level of Salmonella gallinarum.Detected by competitive RT-PCR,the mRNA expression of acrA and acrB genes in the resistant strains significantly increased(p<0.01)compared with that of the control strain C79-13.The mRNA expression level of acrB gene(increased from 1.6-to 2.9-folds)was consistent with that of acrA gene(increased from 1.6-to 2.8-folds),which increased with the drug resistance level.However,gene mutation of acrA gene showed no correlation with its mRNA expression level,indicating that gene mutation did not affect the expression of AcrAB pump itself.The results suggested that the overexpression rather than the gene mutation of AcrAB efflux pump was an important factor causing the high level drug resistance of Salmonella gallinarum.展开更多
This study examined users' querying behaviors based on a sample of 30 Chinese college students from Peking University. The authors designed 5 search tasks and each participant conducted two randomly selected searc...This study examined users' querying behaviors based on a sample of 30 Chinese college students from Peking University. The authors designed 5 search tasks and each participant conducted two randomly selected search tasks during the experiment. The results show that when searching for pre-designed search tasks, users often have relatively clear goals and strategies before searching. When formulating their queries, users often select words from tasks, use concrete concepts directly, or extract 'central words' or keywords. When reformulating queries, seven query reformulation types were identified from users' behaviors, i.e. broadening, narrowing, issuing new query, paralleling, changing search tools, reformulating syntax terms, and clicking on suggested queries. The results reveal that the search results and/or the contexts can also influence users' querying behaviors.展开更多
[目的]研究橡胶林下不同生长年份砂仁果实代谢物及其与根际土壤理化性质和根际微生物的相关性,为橡胶林下不同生长年份砂仁的药效评价及砂仁代谢物资源的挖掘与利用提供理论依据。[方法]采用气相色谱仪结合飞行时间质谱仪(GC-TOF-MS)检...[目的]研究橡胶林下不同生长年份砂仁果实代谢物及其与根际土壤理化性质和根际微生物的相关性,为橡胶林下不同生长年份砂仁的药效评价及砂仁代谢物资源的挖掘与利用提供理论依据。[方法]采用气相色谱仪结合飞行时间质谱仪(GC-TOF-MS)检测不同生长年份(3、4、5和6年)砂仁果实样品(SR3、SR4、SR5和SR6)中的代谢物含量,分析橡胶林下不同生长年份砂仁果实样品两两比较和多组比较中的差异代谢物,筛选显著差异代谢物并进行KEGG代谢通路富集分析,筛选极显著富集的KEGG代谢通路。对极显著差异代谢物之间及根际土壤理化性质指标和根际微生物群落优势门与极显著差异代谢物之间进行相关分析。[结果]在不同生长年份的砂仁果实中共鉴定出261种代谢物。在SR4 vs SR3组、SR5 vs SR3组、SR6 vs SR3组、SR4 vs SR5组、SR4 vs SR6组和SR5 vs SR6组分别鉴定出13、54、49、54、40和5种显著差异代谢物。SR5 vs SR3组和SR4 vs SR5组的显著差异代谢物数量最多(54种)。SR4 vs SR5组中上调的显著差异代谢物最多(34种)。在62条代谢通路中最终筛选获得5条极显著富集的代谢通路(P<0.001),P最小的代谢通路为ABC转运蛋白通路,其次为类黄酮的生物合成代谢通路。相关分析结果显示,大部分极显著差异代谢物之间存在着较强的相关性,除速效钾含量与所有极显著差异代谢物均无显著相关(P>0.05,下同)外,其他砂仁根际土壤理化性质指标与17种极显著差异代谢物间相关性较强。5个优势细菌门中,变形菌门与棉子糖呈显著负相关(P<0.05,下同);放线菌门与丙酮醇呈显著正相关。在5个优势真菌门中,接合菌门与葡庚糖酸呈显著正相关,球囊菌门与绝大多数极显著差异代谢物之间相关性较强。[结论]在橡胶林下不同生长年份砂仁果实样品多组比较中共筛选出17种极显著差异代谢物,一些代谢物(如丙酮醇、棉子糖和L-赖氨酸等)的含量可能受砂仁根际土壤理化性质和根际土壤微生物群落的影响。展开更多
基金financially supported by the Key Research and Development Program of Shandong,China(No.2021SFGC0701)。
文摘The present study investigated the effects of varying protein source combinations and feeding strategies on the growth,health and organoleptic quality of the large yellow croaker(Larimichthys crocea).Three iso-nitrogenous and iso-lipidic diets were formulated.The control diet was made with 62%fish meal(FM).The other two experimental diets were formulated by replacing 45%FM with 22.5%mealworm(TM)and 22.5%cottonseed protein concentrate(CPC),or with 22.5%TM and 22.5%Clostridium autoethanogenum protein(CAP),respectively.The three kinds of diet were named as A1,A2 and A3,respectively.Five groups of large yellow croaker were fed with two different strategies:the first three groups were continuously fed with A1,A2 and A3 diets,respectively.The fourth group was alternately fed with A1 and A2 diet every 5 days.The fifth group was alternately fed with A1 and A3diet every 5 days.The five groups were named D1,D2,D3,D1-2 and D1-3,respectively.Results showed that D2 and D3 groups exhibited significantly lower weight gain rate(WGR)and higher feed conversion ratios(FCR)compared to the D1 group.The D1-2 and D1-3 groups exhibited improved WGR and significantly reduced FCR compared to the D2 and D3 groups.The A2 and A3 diets significantly suppressed digestive enzymes'activities compared to A1,whereas alternate-feeding groups significantly enhanced the enzyme activities.Compared to the D1 group,D2 and D3 groups significantly downregulated mRNA expression levels of intestinal antiinflammatory cytokines and upregulated the expression of pro-inflammatory mediators.The anti-inflammatory abilities in the D1-2and D1-3 groups were significantly higher than those in the D2 and D3 groups.Additionally,diets containing TM+CAP and TM+CPC protein sources enhanced ventral redness and yellowness indices.Considering the growth,digestion,immunity and organoleptic quality of large yellow croaker,it is recommended to replace up to 45%of FM with TM+CPC and use an alternate-feeding strategy.
基金Supported by the Application Technology Research and Development Project in Heilongjiang Province of China(PC13S03)the Foundation of Heilongjiang Province Educational Committee of China(11541030)。
文摘Salmonella gallinarum has shown multiple drug resistance(MDR),especially high level fluoroquinolone(FQ)resistance in recent years.To determine whether the active efflux system was responsible for high-level FQ resistance,this research studied AcrAB efflux pump in Salmonella gallinarum on molecular level.The resistant strains were induced by standard strain C79-13 with ciprofloxacin in vitro.With carbonylcyanide-p-chlorophenyl hydrazone(CCCP)as an energy inhibitor,efflux inhibition test initially showed the potential impact of efflux pump on drug resistance.Sequence analysis of acrA gene indicated that gene mutation of AcrAB efflux pump was not definitely associated with MDR and drug resistance level of Salmonella gallinarum.Detected by competitive RT-PCR,the mRNA expression of acrA and acrB genes in the resistant strains significantly increased(p<0.01)compared with that of the control strain C79-13.The mRNA expression level of acrB gene(increased from 1.6-to 2.9-folds)was consistent with that of acrA gene(increased from 1.6-to 2.8-folds),which increased with the drug resistance level.However,gene mutation of acrA gene showed no correlation with its mRNA expression level,indicating that gene mutation did not affect the expression of AcrAB pump itself.The results suggested that the overexpression rather than the gene mutation of AcrAB efflux pump was an important factor causing the high level drug resistance of Salmonella gallinarum.
基金partially supported by China Scholarship Council(Grant No.:2009601175)
文摘This study examined users' querying behaviors based on a sample of 30 Chinese college students from Peking University. The authors designed 5 search tasks and each participant conducted two randomly selected search tasks during the experiment. The results show that when searching for pre-designed search tasks, users often have relatively clear goals and strategies before searching. When formulating their queries, users often select words from tasks, use concrete concepts directly, or extract 'central words' or keywords. When reformulating queries, seven query reformulation types were identified from users' behaviors, i.e. broadening, narrowing, issuing new query, paralleling, changing search tools, reformulating syntax terms, and clicking on suggested queries. The results reveal that the search results and/or the contexts can also influence users' querying behaviors.
文摘[目的]研究橡胶林下不同生长年份砂仁果实代谢物及其与根际土壤理化性质和根际微生物的相关性,为橡胶林下不同生长年份砂仁的药效评价及砂仁代谢物资源的挖掘与利用提供理论依据。[方法]采用气相色谱仪结合飞行时间质谱仪(GC-TOF-MS)检测不同生长年份(3、4、5和6年)砂仁果实样品(SR3、SR4、SR5和SR6)中的代谢物含量,分析橡胶林下不同生长年份砂仁果实样品两两比较和多组比较中的差异代谢物,筛选显著差异代谢物并进行KEGG代谢通路富集分析,筛选极显著富集的KEGG代谢通路。对极显著差异代谢物之间及根际土壤理化性质指标和根际微生物群落优势门与极显著差异代谢物之间进行相关分析。[结果]在不同生长年份的砂仁果实中共鉴定出261种代谢物。在SR4 vs SR3组、SR5 vs SR3组、SR6 vs SR3组、SR4 vs SR5组、SR4 vs SR6组和SR5 vs SR6组分别鉴定出13、54、49、54、40和5种显著差异代谢物。SR5 vs SR3组和SR4 vs SR5组的显著差异代谢物数量最多(54种)。SR4 vs SR5组中上调的显著差异代谢物最多(34种)。在62条代谢通路中最终筛选获得5条极显著富集的代谢通路(P<0.001),P最小的代谢通路为ABC转运蛋白通路,其次为类黄酮的生物合成代谢通路。相关分析结果显示,大部分极显著差异代谢物之间存在着较强的相关性,除速效钾含量与所有极显著差异代谢物均无显著相关(P>0.05,下同)外,其他砂仁根际土壤理化性质指标与17种极显著差异代谢物间相关性较强。5个优势细菌门中,变形菌门与棉子糖呈显著负相关(P<0.05,下同);放线菌门与丙酮醇呈显著正相关。在5个优势真菌门中,接合菌门与葡庚糖酸呈显著正相关,球囊菌门与绝大多数极显著差异代谢物之间相关性较强。[结论]在橡胶林下不同生长年份砂仁果实样品多组比较中共筛选出17种极显著差异代谢物,一些代谢物(如丙酮醇、棉子糖和L-赖氨酸等)的含量可能受砂仁根际土壤理化性质和根际土壤微生物群落的影响。
