| 2 | Experimental proof for the regulation of Salmonella typhimurium purB by purR显示文摘Salmonella typhimurium purB encodes adeny-losuccinate lyase (ASL), the enzyme that catalyzes step 8 in the pathway for de novo synthesis of inosine 5’-monophos-phate (IMP) and also the final reaction in the two-step sequence from IMP to adenosine monophosphate (AMP). The nucleotide sequence ofpurB was obtained by the genetic map and sequence homologous analysis. The conserved pur operator in purB was identified to be located 185 bp downstream of the initiation codon and overlaps codons 62 - 67 in the protein-coding region. The binding of PurR to this operator was demonstrated by gel retardation experiment and site-directed mutagenesis, indicating that the purB is under the control of purR. We also answered why previous study had conflicting report concerning the regulation of purB by purR by identifying the junction site of purB to lacZ in a purB-MudJ (lacZ, Kan’) fusion strain. This result strongly supports that the purB is the second gene in the ycfC-purB operon. | ZHANG Haining HUANG Yi QIN Junchuan WANG Aoquan | 2001 | Chinese Science Bulletin2001，46，14： | 0 |
| 3 | Red list assessments of Chinese higher plants显示文摘Based on the two most recent assessments of Chinese higher plants in 2013 and 2020,of 34,450 and 39,330 species,respectively,we analysed the threatened status of Chinese higher plants.In 2020,around 4,088(10.39%)of the assessed species in China are threatened,2,875(7.31%)Near Threatened,27,593(70.16%)not currently threatened and categorised as Least Concern and 4,752(12.08%)categorised as Data Deficient.While in 2013,3,767(10.93%)of the assessed higher plants in China are threatened,2,723(7.90%)Near Threatened,24,296(70.53%)Least Concern and 3,612(10.48%)Data Deficient.Estimates of the Red List Index in the two years show different patterns when using different weighting methods with the equal steps weighting method showing a slight decrease(0.91675-0.91495)and the extinction risk weighting method showing a slight increase(0.98792-0.98797).We inferred that China's threatened plant species were likely/relatively effectively protected.However,attention should also be given to the non-threatened species in the future as an additional strategy for their conservation,to maintain their non-threatened status. | Liping Li Haining Qin Eimear Nic Lughadha Yaomin Zheng Huawei Wan Jack Plummer Melanie-Jayne R.Howes Huiyuan Liu Yangming Jiang Tuo Wang Huihui Zhao Zhanfeng Shen Huiping Huang | 2023 | International Journal of Digital Earth2023，16，1： | 0 |
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