Dali County Research Articles

The Prevalence and Causes of Visual Impairment in an Elderly Chinese Bai Ethnic Rural Population: The Yunnan Minority Eye Study

To assess the prevalence and causes of visual impairment in the elderly Bai ethnic group in rural China. Random cluster sampling was used to identify the Bai ethnic group 50 years and older living in the Dali county of Yunnan, China. Presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) were measured using the Early Treatment Diabetic Retinopathy Study visual chart. Blindness and low vision were defined according to World Health Organization criteria. The major cause of visual impairment was identified for all participants who were visually impaired. Of the 2742 eligible individuals, 2133 (77.8%) participated in the study, and 2115 (77.1%) had visual acuity data available. With the PVA, the prevalence of blindness and low vision was 3.59% and 15.22%, respectively. When the BCVA was used, these rates were reduced to 2.88% and 7.75%. Blindness and low vision were associated with older age and lack of education, but no sex difference was seen. Based on the BCVA, the predominant causes of blindness were cataract (70.5%), corneal opacity (8.2%), and glaucoma (6.6%). The majority of PVA-defined low vision cases were attributable to cataract (53.0%) and uncorrected refractive error (22.0%). A higher rate of visual impairment was seen in this Bai nationality sample than has been reported from the Han nationality population in rural China. Since potentially treatable eye disease, cataract, and uncorrected refractive error were the most important causes of visual impairment in this population, affordable provision of surgery and low-vision rehabilitation programs would help to address this problem.

Occurrence of Chilli veinal mottle virus in Nicotiana tabacum in Yunnan, China

Flue-cured tobacco (Nicotiana tabacum) is an important crop in Yunnan Province, China. During a survey in July 2010, tobacco plants (N. tabacum cv. Yunyan 85) in the fields near Dali County in the northwest Yunnan Province of China had symptoms of chlorosis along leaf veins and later showed symptoms of white or brown necrosis along the veins. In 10 surveyed fields in Baizhishu Village in the city of Weishan, a commercial tobacco field (10 ha) developed virus-like disease symptoms; the incidence of affected plants ranged from 0.5 to 3%, which caused obvious economic losses. An isolate (YN75) was collected at random from five symptomatic leaves sampled from five plants. Negative staining of crude extracts of the infected leaves and subsequent electron microscopy revealed flexuous rods of 12 to 13 × 750 nm. Pinwheel-like inclusion bodies were abundant in thin sections of infected leaves. The particle size suggested a species of Potyviridae. Thus, the isolate was assayed in double antibody sandwich-ELISA (Agdia, Elkhart, IN) for the presence of Potato virus Y, Tobacco etch virus, and Tobacco vein mottling virus. All antigens gave negative results. Total RNA was extracted from leaves and tested by reverse transcription (RT)-PCR. The primer M4-T (5'-GTT TTC CCA GTC ACG ACT TTT TTT TTT TTT TT-3') was employed for cDNA synthesis described by Chen et al (1). The primer set ChiVMV-F (5'-TAG TTG YGC ATA C (C/G) C AGG AGA GAG-3')/M4 (5'-GTT TTC CCA GTC ACG AC-3') is complimentary to the region of coat protein and 3'-untranslated region of Chilli veinal mottle virus (ChiVMV), respectively. The expected 1,189-bp fragments were amplified from RNA templates and the amplicon was cloned and sequenced (GenBank Accession No. HQ218936). Comparisons of amplicons with the amino acid sequence available in the NCBI database using BLAST showed 91.4% identity with ChiVMV from India (GenBank Accession No. EF213688) and 90.7% with ChiVMV from Taiwan (Accession No. DQ854950). The virus particle size, RT-PCR results, and sequence data revealed that these tobacco plants were infected by ChiVMV. To our knowledge, this is the first report of ChiVMV infecting N. tabacum in China. Reference: (1) J. Chen et al. Arch. Virol. 146:757, 2001.

An insight into the genetic variation of Schistosoma japonicum in mainland China using DNA microsatellite markers

This study presents the first microsatellite investigation into the level of genetic variation among Schistosoma japonicum from different geographical origins. S. japonicum isolates were obtained from seven endemic provinces across mainland China: Zhejiang (Jiashan County), Anhui (Guichi County), Jiangxi (Yongxiu County), Hubei (Wuhan County), Hunan (Yueyang area), Sichuan 1 (Maoshan County), Sichuan 2 (Tianquan County), Yunnan (Dali County), and also one province in the Philippines (Sorsogon). DNA from 20 individuals from each origin were screened against 11 recently isolated and characterized S. japonicum microsatellites, and a set of nine loci were selected based on their polymorphic information content. High levels of polymorphism were obtained between and within population samples, with Chinese and Philippine strains appearing to follow different lineages, and with distinct branching between provinces. Moreover, across mainland China, genotype clustering appeared to be related to habitat type and/or intermediate host morph. These results highlight the suitability of microsatellites for population genetic studies of S. japonicum and suggest that there may be different strains of S. japonicum circulating in mainland China.

Chronology of the stratum containing the skull of the Dali Man

The field investigations of geomorphology and Quaternary sediment sequences show that the sediment stratigraphic profile containing the skull of the Homo sapiens Daliensis (Dali Man) at Tianshuigou trench, Jiefang Village (109° 44′E, 34°52′N), Dali County, Shaanxi Province, is composed of the loess-paleosol sequence, 17.3 m thick, in the upper part, and the alluvial silts, fine sands and sandy gravels interbedded, 15.4 m thick, in the lower part. There are the well developed layers L1, S1, L2 and S2 in the loess-paleosol sequence of the profile, which are comparable; to those of the Luochuan loess section on the basis of magnetic succeptibility measurements and IRSL dating of the loess samples. An alluvial gravel layer, where the skull of the Dali Man was discovered, is in 13 m beneath the bottom of paleosol S2, implying that, the age of the Dali Man must be older than about 247 kaBP when the paleosol S2 began to be developed. The samples of mammal animal tooth and shell fossils from the gravel layer containing the skull of the Dali Man have been dated by uranium series and ESR methods respectively. Based on the multiple dating results and the stratigraphic chronology, the age of the Dali Man, therefore, would be estimated as older than 250 kaBP and younger than 350 kaBP, and reasonably estimated as 260–300 kaBP.

Mosses New to Mainland China

Mosses New to Mainland China