Allosteric regulation of nitrate transporter NRT via the signaling protein PII.

Coordinated carbon and nitrogen metabolism is crucial for bacteria living in the fluctuating environments. Intracellular carbon and nitrogen homeostasis is maintained by a sophisticated network, in which the widespread signaling protein PII acts as a major regulatory hub. In cyanobacteria, PII was proposed to regulate the nitrate uptake by an ABC (ATP-binding cassette)-type nitrate transporter NrtABCD, in which the nucleotide-binding domain of NrtC is fused with a C-terminal regulatory domain (CRD). Here, we solved three cryoelectron microscopy structures of NrtBCD, bound to nitrate, ATP, and PII, respectively. Structural and biochemical analyses enable us to identify the key residues that form a hydrophobic and a hydrophilic cavity along the substrate translocation channel. The core structure of PII, but not the canonical T-loop, binds to NrtC and stabilizes the CRD, making it visible in the complex structure, narrows the substrate translocation channel in NrtB, and ultimately locks NrtBCD at an inhibited inward-facing conformation. Based on these results and previous reports, we propose a putative transport cycle driven by NrtABCD, which is allosterically inhibited by PII in response to the cellular level of 2-oxoglutarate. Our findings provide a distinct regulatory mechanism of ABC transporter via asymmetrically binding to a signaling protein.

A survey on anemia among children under 7 years of age from 15 minority ethnic groups in Yunnan / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the level and distribution characteristics of anemia of the minority ethnic group children in Yunnan.</p><p><b>METHOD</b>The cases with anemia were surveyed from 13 336 samples of 15 minority ethnic groups and Han children in Yunnan by Taking the method of random cluster sampling.</p><p><b>RESULT</b>The prevalence of anemia among the children under 7 years of age of 15 ethnic groups of minority in Yunnan was 13.6%. There are differences among the different ethnic groups (χ(2) = 716.33, P < 0.01), the highest was 26.6% in Jingpo, the lowest was 3.5% in Bai. There were differences among the different regions, the prevalence of anemia was high in the border regions City, the highest was 23.8% in Dehong; the prevalence of anemia was low in inland cities, the lowest was 2.7% in Fugong, and was higher in border areas. The prevalence of anemia was higher in boys (13.6%) than in girls (12.1%). There were differences among the different age in the different ethnic groups (6 months to 1 years old: χ(2) = 70.52, P < 0.01; 1 - 2 years old:χ(2) = 185.86, P < 0.01; 2 - 5 years old: χ(2) = 296.12, P < 0.01; 5 - 6 years old:χ(2) = 107.11, P < 0.01; 6 - 7 years old:χ(2) = 185.02, P < 0.01), the highest was 59.0% of Deang in 1 to 2 years old children. The trend of change was that the highest prevalence was seen in 6 months to 1 year old children, the prevalence gradually declined among older children, but rose again in children 6 years of age or older.</p><p><b>CONCLUSION</b>The prevalence of anemia was 13.6% among the children of 15 ethnic minority under 7 years of age in Yunnan. There were differences among different ethnic groups of minority in different prefectures. There were differences among different ethnic groups of different age groups, but it was highest in 6 months to 1 year old children, it declined among older children, and rose in children 6 years of age or older. The prevalence of anemia was related to the ethnic and geographic factors.</p>

G6PD deficiency among children under 7 years old from Yunnan with unique ethnic minority origin / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the epidemiological status of glucose-6-phosphate dehydrogenase (G6PD) deficiency among children from Yunnan with unique ethnic origins.</p><p><b>METHODS</b>DNA samples from 11759 children were tested with fluorescent spot test, G6PD/6PGD quantitative ratio assay and hemoglobin electrophoresis.</p><p><b>RESULTS</b>The detection rate of G6PD deficiency was 2.5%, for which boys were significantly greater than girls (3.5% vs. 1.4%, P<0.05). Significant differences were also detected among children from different ethnic groups and different regions. For ethnic Han Chinese, the detection rate was 0.7%, which was lower than the majority of ethnic minorities. By regression analysis, altitude of residence and family history both have significant influence on the calculated rate.</p><p><b>CONCLUSION</b>Occurrence of G6PD deficiency seems to be influenced by gender. It also varies substantially between different ethnic groups as well as regions, e.g., more common in south. It also showed a declining trend after years of diagnosis and intervention. This survey may provide a valuable basis for counseling of G6PD deficiency in Yunnan.</p>

Epidemiological study on thalassemia among the children of 0-7 years old among the six ethnic groups in Xishuangbanna and Dehong of Yunnan province / 中华流行病学杂志

Objective To investigate the prevalence rate of thalassemia among children of 0-7 years old,from six ethnic groups in Xishuangbanna and Dehong.Yunnan province.Methods 4973 blood samples from children under 7 years old were automatically undergone blood cell count,red cell osmotic fragility and hemoglobin electrophoresis testings.Results The incidence rates of thalassaemia,β-thalassemia was 37.4%,and α-thalassaemia were 22.6%and 14.7% respectively.The thalassaemia incidence rates were significantly different among age groups but not in gender. The incidence of α-thalassaemia was decreasing along with the increase of age.while the incidence of β-thalassaemia was increasing along with the increase of age.Xishuangbanna had the higher incidence than in Dehong and the differences were significant between counties.The incidence of thalassemia of Mengla ranked the first(52.2%)in Xishuangbanna,The difierences between different regions and different nationalities were significant,with β-thalassemia of Achang ranked the first(40.6%),The incidence of α-thalassemia among Han ranked the first as 45.5% while α-thalassaemia and β-thalassemia were different in regions.α-thalassaemia and β-thalassemia were significantly different between different ethnic people in the same regions.Multiple factor analysis showed that region seemed to be a risk factor and the mother's ethnicity was a protective factor and dependent variable on thalassaemia.Conclusion The incidence of thalassaemia in Yunnan Xishuangbanna and Dehong was high among children under the age of 7 and were related to ethnic and regional differences in the areas.Specific genes were proliferated along with the extension of time.Our data provided valuable information on prevention and genetic studies on thalassaemia in the minorities of Xishuangbanna and Dehong in Yunnan province.

Epidemiological study of thalasaemia among children in Xishuangbanna, Dehong and Nujiang of Yunnan province / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the carrier rate of thalasaemia among the children of 10 minority ethnic groups in 3 border states (Xishuangbanna, Dehong and Nujiang) of Yunnan Province.</p><p><b>METHODS</b>A total of 6562 samples of children under 10 years old were analyzed by blood cell automatic analysis and hemoglobin electrophoresis.</p><p><b>RESULTS</b>The overall carrier frequency of thalasaemia was highest (46.2%) in Dehong, and lowest (30.6%) in Nujiang. The carrier frequency of beta-thalasaemia was the highest (40.6%) in Achang, and lowest (2.5%) in Dulong. The carrier frequency of alpha-thalasaemia was the highest (22.1%) in Dai from Xishuangbanna, followed by Dulong (19.1%).</p><p><b>CONCLUSION</b>Thalasaemia carrier rates were high among the children of 10 minority ethnic groups in Yunnan. There were regional differences in their incidences. The results provide a valuable basis for thalasaemia prevention in Yunnan minorities in the three border states.</p>