Objective:To analyze the epidemiological characteristics of novel coronavirus positive cases including confirmed cases with clinical symptoms and asymptomatic infected cases in Guangzhou.Methods:Epidemiological data were collected on the nucleic acid positive cases of COVID-19 in Guangzhou from January to September 2020. The epidemiological characteristics, the distribution of time intervals between the confirmed/isolation date and the date of the first positive detection were analyzed, at last the influencing factors for the confirmed cases and asymptomatic infected persons were discussed.Results:From January 7 to September 4 in 2020, a total of 1 097 nucleic acid positive cases were identified, including 658 confirmed cases (59.98%) and 439 asymptomatic infected cases (40.02%). Among the 658 confirmed cases, the median age was 42 years old, the cases indicated two significant peaks. one of the peaks was related to the imported and associated cases from Hubei province, and the other peak was connected with individuals from overseas. In terms of 439 asymptomatic infected cases, the median age was 32 years old. There were two stages in these cases. The first stage followed the second peak of confirmed cases, and the second stage overlapped with the confirmed cases in Guangzhou when the epidemic was in a period of normal prevention and control, mainly related to imported cases from abroad. The asymptomatic infected persons accounted for 57.32% in all the imported infected cases. In both of asymptomatic and symptomatic cases, the positive rate of pharyngeal swabs was higher than that of nasopharyngeal swabs and anal swabs. There were statistically significant differences in age, source of infection and gender composition between confirmed cases and asymptomatic infected persons ( P<0.05). Older age groups were more likely to have clinical symptoms, with ≥40 years being the risk factor for confirmed cases (OR=2.334, P=0.001), and 20-39 years less likely to have clinical symptoms (OR=0.620, P=0.047), compared with the 0-19 years old group. Compared with those infected in China, those infected abroad were less likely to develop clinical symptoms and became confirmed cases (OR=0.723, P=0.013). Women were more likely to have clinical symptoms than men (OR=1.574, P=0.001). Conclusions:At present, asymptomatic infected persons and confirmed patients with clinical symptoms co-existed, and the number of asymptomatic infected patients was higher than that of confirmed cases in Guangzhou. High age, domestic infection and female may be risk factors for confirmed cases. It was of great value to further explore these underlying mechanisms for the prevention and treatment of the COVID-19.

Using RACE with a Fagopyrum dibotrys callus cDNA library, one clone, named FdMYBP1, encoding a putative R2R3 MYB protein was identified. FdMYBP1 appeared to be a full-length cDNA of 1159 bp encoding a protein of 265 amino acids. Through structure and property analysis of FdMYBPI with bioinformational methods, it was found that the amino acid sequence of FdMYBP1 showed great homology to other MYBP with the R2R3 repeat region in the N-terminus. Southern blot analysis indicated that FdMYBP1 belongs to a single copy gene in F. dibotrys genomes. The FdMYBP1 gene has the same classic characters with other MYBP and probably involved in the pathway of flavonoid metabolisms.
Cloning, Molecular ; Fagopyrum ; genetics ; metabolism ; Gene Expression Regulation, Plant ; Molecular Sequence Data ; Plant Proteins ; genetics ; metabolism ; Proto-Oncogene Proteins c-myb ; genetics ; metabolism

Objective:To analyze the contagiousness and secondary attack rate of 2019 novel coronavirus in cluster epidemics in Guangzhou and provide evidence for the prevention and control of COVID-19.Methods:All the individuals identified to be infected with 2019-nCoV in Guangzhou, including confirmed cases and asymptomatic cases, were included and classified as imported cases and local cases. The first case of each cluster epidemic was defined as index case, and the number of subsequent infections was calculated to evaluate the contagiousness and secondary attack rate of 2019 novel coronavirus in the shortest incubation period of 1-3 days.Results:As of 18 February, 2020, a total of 349 cases of 2019-nCoV infection, including 339 confirmed cases (97.13 %) and 10 asymptomatic cases (2.87 %) were reported in Guangzhou. There were 68 clusters involving 217 2019-nCoV infection cases (210 confirmed cases and 7 asymptomatic cases). The median number of subsequent infections caused by an index case in a cluster epidemic was 3, among which 2 were confirmed cases and 1 was asymptomatic cases, respectively. The average number of contagiousness was 2.18 in shorted incubation period of 1-3 days (The average number of infected cases were 2.18 cases by the index case in a cluster epidemic), the average infection number in family members was 1.86, and the infection ratio of family member transmission was 85.32 % (1.86/2.18). The secondary attack rate in close contacts with shortest incubation period of 1-3 days was 17.12 %-18.99 %, the secondary attack rate in family members was 46.11 %-49.56 %. Conclusions:The cluster epidemic of COVID-19 in Guangzhou mainly occurred in families, the contagiousness was high. It is necessary to strengthen the prevention and control to reduce the community transmission of COVID-19.

OBJECTIVETo establish a method for isolation of the total RNA from Fagopyrum cymosum callus.

METHODThe improved method combining that of CTAB extraction with the LiCl precipitation was used to isolate the total RNA from the four F. cymosum callus. The quality of the RNA was detected by UV spectrophotometric analysis, 0.8% non-denaturing agarose gel electrophoresis and RNA reverse transcription.

RESULTThe bands of 28S and 18S could be seen clearly by agarose gel electrophoresis, and the value of A260/A280 was between 1.9 and 2.0. The cDNA which was reverse-transcribed by the total RNA showed a wide length rage of 500 bp-5 kb.

CONCLUSIONThe RNA extracted by this method meets the requirement of reverse transcription-polymerase chain reaction (RT-PCR), construction of cDNA libraries, et al. This improved method can be used to isolate the total RNA from F. cymosum callus with the advantage of simpleness, efficiency and low cost.

Since the outbreak of COVID-19, it has spread rapidly throughout the country and even in the world. As a first tier city, Guangzhou is also the South Gate of China, with large population mobility and severe and complex prevention and control situation. Guangzhou CDC, together with Tencent and Alibaba Cloud, has made full use of its artificial intelligence technology to carry out a series of practices in case transmission chain analysis, close contact and other key personnel management, front-line staff prevention and control skills training and convenience services. Through the application of artificial intelligence in different scenarios, the difficulties and challenges in the prevention and control are solved, and the speed of epidemic prevention and control is increased.

Since the outbreak of COVID-19, it has spread rapidly throughout the country and even in the world. As a first tier city, Guangzhou is also the South Gate of China, with large population mobility and severe and complex prevention and control situation. Guangzhou CDC, together with Tencent and Alibaba Cloud, has made full use of its artificial intelligence technology to carry out a series of practices in case transmission chain analysis, close contact and other key personnel management, front-line staff prevention and control skills training and convenience services. Through the application of artificial intelligence in different scenarios, the difficulties and challenges in the prevention and control are solved, and the speed of epidemic prevention and control is increased.

Objective To investigate the effects of terahertz(THz)radiation on mouse testicular tissue and its potential molecular mechanisms.Methods A total of 125 male C57BL/6J mice(6～8 weeks old)were randomly divided into control group and low-,medium-and high-radiation power groups.The mice of the latter 3 groups were exposed to THz radiation at a frequency of 2.5 T,with an average power density of 38,115,or 318 mW/cm2,for 5 or 10 min.The detection time was immediately or 24 h after exposure.HE staining was used to observe pathological damage.ELISA was employed to detect the expression of inflammatory factors in testicular tissue.RNA-seq was utilized to detect the global changes of gene expression.The differentially expressed genes(DEGs)were screened and bioinformatics was used to cluster them.The screened genes were further analyzed with RT-qPCR to determine the time-dependent and dose-dependent relationships of the expression with THz exposure.Finally,sperm quality was evaluated morphologically using a microscope.Results Three doses of THz radiation exposure did not cause significant pathological damages to mouse testicular tissue.TNF-α expression was increased immediately after exposure at average power density of 115 mW/cm2(P＜0.01),and the expression of IL-1β and TNF-α were both increased when the dose reached 318 mW/cm2(P＜0.01).However,all the 3 factors returned to normal levels in 24 h after exposure.RNA-seq results showed that THz radiation exposure caused abnormal expression of 56 genes.Cluster analysis indicated that these DEGs were mainly enriched in immune and inflammatory responses,enzyme activity,sperm development and capacitation functions.Then for 5 selected key genes,Crisp1,Adam7,Ltf,Rnase9,and Bsph1,the expression of Crisp1 and Rnase9 was decreased immediately after exposure to 115 mW/cm2 THz radiation,the dose of 318 mW/cm2 resulted in obvious changes in the expression of the 5 genes(P＜0.05),and their expression returned to normal levels in 24 h after exposure.Morphological observation displayed that exposure to all the 3 doses of THz had no influence on sperm quality.Conclusion THz radiation exposure causes temporary inflammatory response in testicular tissue and abnormal expression of sperm functions-related genes.However,these changes return to normal 24 h after exposure,and additionally,do not impair sperm quality.