[Physiological responses and tolerance to drought stress of different watermelon genotypes.] / ä¸åŒè¥¿ç“œåŸºå› åž‹å¯¹å¹²æ—±èƒè¿«çš„ç”Ÿç†å“åº”åŠå ¶æŠ—æ—±æ€§è¯„ä»·.

With the continuous drought stress treatment to 12 pot-grown watermelon genotypes originated from different regions, the influence of drought stress on plant height, root length, fresh mass and dry mass was studied, and the physiological responses of these genotypes to drought stress were compared. Drought resistance of these watermelon genotypes was preliminarily determined according to the drought injury, and then confirmed by membership function evaluation method. We found that the watermelon genotypes exhibited great difference in drought tolerance based on the occurrence of drought injury and the degree of injury severity. Drought stress reduced plant height, shoot- and root- fresh mass as well as shoot- and root- dry mass, while increased the root/shoot ratio for most genotypes; but for root length and root dry mass, it had both positive and negative effects depending on the tested genotype. Compared with the control, all drought-treated watermelon genotypes exhibited a decline in leaf relative water content and chlorophyll content, as well as increases in MDA, H2O2, O2-· and proline contents. Different watermelon genotypes displayed diversity in soluble protein content and antioxidant enzyme activity. Our results showed that three wild watermelon genotypes including M20, Y-2, and KY-3 were drought tolerant while Y34, 04-1-2 and Golden Girl were drought sensitive, and the rest genotypes were among the medium.

Gastroenteritis outbreaks caused by Norovirus genotype II.7 in a college in China (Zhuhai, Guangdong) in 2011.

BACKGROUND: Noroviruses are the most common cause of epidemic gastroenteritis worldwide. Noroviruses are comprised of at least five genogroups (GI-GV) and >35 genotypes. GII.7 is a nonpredominant genotype associated with Norovirus outbreaks. On November 17, 2011, Zhuhai Center for Disease Control monitored an increasing number of gastroenteritis cases at a local college. To determine the causes and control the outbreak effectively, we carried out an epidemiologic investigation. METHODS: Suspected cases were defined as those with one of the following symptoms: nausea, vomiting, abdominal pain, or diarrhea presenting on or after November 15 among the people who lived at the college. Probable cases were defined as cases with vomiting or diarrhea over three times per day on or after November 15. Confirmed cases were suspected or probable cases positive for Norovirus (nucleic acid). We conducted a case-control study to identify risk factors of the outbreak. Norovirus was tested by real-time reverse transcription-polymerase chain reaction, and Norovirus polymerase chain reaction products were further sequenced. RESULTS: In total, 63 cases were identified, which were scattered in all 14 departments of the college. The outbreak lasted for 84 h. Time distribution mode indicated a point-source outbreak. Fifty-one cases and 94 controls were contacted. Seventy-five percent of the cases compared to 19% of the controls were exposed to delicatessens (various salad and meat products) from the "Y" convenience store (odds ratio=12, 95% confidence interval 5.4-28). Laboratory tests showed 14 of the 15 cases and two asymptomatic food handlers were positive for Norovirus nucleic acid. There was 100% similarity between the cases and the food handlers when we compared the nucleotide sequences of Norovirus, which clustered with GII.7 genotype. CONCLUSIONS: Delicatessens from the "Y" convenience store were associated with the GII.7 Norovirus outbreak. We strongly recommend food supervision and quality control in convenience stores to decrease the risk of future Norovirus outbreaks.

[Epidemiological and etiological characteristics of diarrheal disease among children under 5 years of age in Guangdong province, in 2012].

OBJECTIVE: To analyze the epidemiological and etiological characteristics of diarrheal disease among children under 5 years of age in Guangdong province, in 2012. METHODS: 64 hospitals in 21 cities were chosen as the diarrheal syndromic surveillance sites, of which 14 hospitals were selected to carry out etiological surveillance among children under 5 years of age, including isolation and culture of both Vibrio cholera and Shigella as well as nucleic acid detection of rotavirus and norovirus by PCR. Descriptive method was used to analyze data from syndromic and etiological surveillance programs on diarrheal, from 1932 parents of the children. RESULTS: In 2012, the outpatient attendance rate on diarrheal among children under 5 years was 0.8%. The proportion of diarrheal in children under 5-year-olds was 63.5%, among the total number of diarrheal outpatients at the outpatient clinics under surveillance program. The morbidity of infectious diarrhea was 1454.5/10 million in children under 5 years of age. A total number of 1932 specimens were collected from children under 5 years of age, in the outpatient department. Among these specimens,Vibrio cholera appeared all negative but one was Shigella positive and proved to be Sh. sonnei. The positive rates of rotavirus and norovirus were 14.1% (273/1932)and 16.9% (326/1932). Both rotavirus and norovirus were found in 24 specimens, with a positive rate as 1.2% . 112 specimens were successfully gene sequenced for rotavirus, of which 33.9% as G1[P8] genotype, 25.9% as G9[P8], 12.5% as G2[P4] and 9.8% as G3[P8] respectively. 90 specimens were successfully gene-sequenced for norovirus, of which 76.7% as G II.4 genotype. Genetic subtypes of G II. 4/2006b, accounted for 50.0% and could be detected around the year except for June and December. New G II. 4/Sydney Strain_2012 was first detected in August and became the predominant in December. In addition, 5 specimens belonged to G I genotype with other 16 subtypes of G II. CONCLUSION: Results from our study proved that children under 5 years of age belonged to high-risk group for diarrheal disease in Guangdong province. Rotavirus and norovirus were both diverse in terms of genome.

[Etiology survey on virus of acute respiratory infection in Guangzhou from 2006 to 2009].

OBJECTIVE: To investigate the pathogens of acute respiratory infection (ARI) in Guangzhou from 2006 to 2009. METHODS: A total of 1554 cases of ARI patients in Second Affiliated Hospital of Guangzhou Medical College from September 2006 to September 2009, were recruited in the survey. The sample of throat and pharyngeal swab were collected from each patient.11 types of virus including influenza A (FluA), influenza B (FluB), adenovirus (ADV), human rhinovirus (HRV), respiratory syncytial virus (RSV), parainfluenza virus type 1, type 2, type 3 (HPIV1, HPIV2, HPIV3), human metapneumovirus (MPV) and human coronavirus (HCoV) type 229E, type OC43 were detected by Fluorescence Quota PCR method. The epidemic feature and clinical characteristic of each virus were then analyzed. RESULTS: Virus were found in 1024 samples in total, accounting for 65.9% (1024/1554). RSV was the most common virus, which was found in 261 samples (16.8%); and followed by HRV as 13.9% (216/1554), FluA as 11.6% (181/1554), MPV as 6.5% (101/1554), FluB as 6.4% (99/1554), HPIV as 4.9% (76/1554), ADV as 3.5% (55/1554) and HCoV as 2.3% (35/1554). HPIV and HCoV shared a similar infection ratio among different age groups. The infection ratio of FluA and FluB was highest among 15-24 years old group, accounting for 16.5% (29/176) and 7.4% (13/176) respectively. MPV, RSV and HRV were the main pathogens caused infection among children under 4 years old, accounting for 9.7% (49/503), 21.7% (109/503) and 18.9% (95/503). The infection ratio of ADV was 6.0% (19/318), which was the most common pathogen among 5-14 years old patients. The incidence rate of HPIV and HRV showed no obvious seasonal features; while the prevalence of FluA, FluB, RSV, ADV, MPV and HCoV changed significantly in different seasons.22.2% (227/1024) ARI patients co-infected other respiratory virus.90.1% (163/181) FluA patients, 88.9% (88/99) FluB patients and 92.7% (51/55) ADV patients had high fever symptoms. CONCLUSION: RSV was the main pathogen of ARI, and the new-found virus MPV was also another crucial pathogen. Some pathogens' incidence rate were related to the season and patient's age. Co-infections of other respiratory virus were also detected in parts of ARI patients.

[Molecular epidemiological characteristics of norovirus gastroenteritis outbreaks in Guangdong from 2005 to 2008].

To study the molecular epidemiological characteristics of norovirus gastroenteritis outbreaks in Guangdong, we collected fecal and anal swabs specimens from 24 outbreaks of acute gastroenteritis from 2005 to 2008 to detect norovirus. Specimens were detected by RT-PCR and then sequenced. The descriptive data were also collected. According to our research, 19 of 24 outbreaks of gastroenteritis were positive for norovirus. The occurrence time was from October to next February mainly. The strains in 2005 belonged to G II-3 genotype and all outbreaks occurred in kindergarten and school. But from autumn of 2006, the outbreaks were all caused by G II-4/2006b variant and occurred in universities and community. The number of outbreaks in 2007 increased greatly and covered all over province. The nucleotide sequences of Guangdong strains in some sites showed high regional identity. Our results showed that with the shift of genotype from G II-3 to G II-4, occurrence of norovirus outbreaks increased greatly. The outbreaks of norovirus caused by G II-4/2006b variant spreaded widely and the involved population covered children and adult, indicating the strong invasiveness of this variant.

[Investigation of human metapneumovirus in children with acute respiratory tract infections in Guangzhou areas].

OBJECTIVE: To find out the status of human metapneumovirus (hMPV) infection in children under 14 years old with acute respiratory tract infections (ARI) in Guangzhou, analyze the epidemiology and clinical characteristics among the hMPV-infected children, and provide some basis for research of hMPV. METHODS: All 521 throat and pharyngeal swabs were collected among the children with acute respiratory tract infections in outpatient departments and those admitted to the wards from September 2006 to August 2008. Then total nucleic acid was extracted from respiratory specimens. The 213 nucleosides of nucleoprotein gene were detected by RT-PCR and 16 strong positive samples were picked to compare with the sequence of hMPV in GenBank after the sequence of the amplification products were determined. Then applied statistical analysis to the data of the collected patients. RESULTS: All 521 samples were detected by RT-PCR, and confirmed that N gene was positive in 39 samples with a detection rate of 7.49%, and the peak time was in October and April. The 16 amplification products were compared by using the analysis of gene sequence. The nucleocapsid protein (N) gene similarity to BJ1897 of Beijing was up to 99%, and to AY550156 of Thailand was up to 97%, genotype B was the most common genotype. CONCLUSION: There existed hMPV infection in children acute respiratory system diseases in Guangzhou areas, in which the children under the age of 6 years were accounted for the main group, however there was no difference in gender. The main symptoms of the patients with hMPV infection were high fever and cough symptom of catarrh. Co-infections other than respiratory virus with hMPV were detected as 41.03% of positive samples.

Multiple outbreaks of acute hemorrhagic conjunctivitis due to a variant of coxsackievirus A24: Guangdong, China, 2007.

Acute hemorrhagic conjunctivitis (AHC) is usually caused by enterovirus 70, coxsackievirus A24(CA24v) and adenoviruses. Several outbreaks of AHC caused by a CA24v have occurred since it was imported into China in 1971. Multiple outbreaks of AHC reappeared in 10 cities of Guangdong during June to November in 2007. The epidemic began in the June, and spread extensively, with a peak in the September. A total of 31,659 cases were reported to center for disease control and prevention of Guangdong, it was estimated that the number of actual AHC was >200 thousands. Forty conjunctival swab specimens were collected from the cases diagnosed clinically with AHC. (RT)-PCR testing on these conjunctival specimens revealed the presence of an enterovirus, and this was confirmed by 16 isolates. We demonstrated the most likely etiological agent for the multiple outbreaks was a variant of coxsackievirus A24 by molecular typing using a partial VP1 sequence. Sequence comparison and phylogenetic analyses of the VP1 and 3Cpro gene regions were performed by Neighbor-joining method, the strains from different outbreaks and different geographical areas within Guangdong had no sequence divergence in 2007. The representative isolates from mainland of China including Hangzhou, Ningbo, Beijing, Yunnan, Liaoning, and Henan were analyzed in this study. Phylogenetic analysis revealed theses isolates were located in different clusters, a close phylogenetic and chronological relationship with Singaporean, South Korean and Thailand isolates had been observed. This confirms CA24v circulated in China's mainland has not evolved independently, but co-evolved with the isolates of Southeast Asia.