Seeing more clearly: recent advances in understanding retinal circuitry     

He S  Dong W  Deng Q  Weng S  Sun W 《Science (New York, N.Y.)》2003,302(5644):408-411

Among 10 breakthroughs that Science announced at the end of 2002 was the discovery of a photosensing (melanopsin-containing) retinal ganglion cell (RGC) and its role in entraining the circadian clock. This breakthrough exemplifies the ultimate goal of neuroscience: to understand the nervous system from molecules to behavior. Light-sensing RGCs constitute one of a dozen discrete RGC populations coding various aspects of visual scenes by virtue of their unique morphology, physiology, and coverage of the retina. Interestingly, the function of the melanopsin-containing RGCs in entraining the circadian clock need not involve much retinal processing, making it the simplest form of processing in the retina. This review focuses on recent advances in our understanding of retinal circuitry, visual processing, and retinal development demonstrated by innovative experimental techniques. It also discusses the advantages of using the retina as a model system to address some of the key questions in neuroscience.  相似文献   

Molecular mechanisms underlying pig oocyte maturation and fertilization   总被引：2，自引：0，他引：2  

Sun QY  Nagai T 《The Journal of reproduction and development》2003,49(5):347-359

Since the pig is not only an important farm animal, but also a model animal for biomedical applications, the development of reproductive technologies in this species has been very important. In vitro oocyte maturation and fertilization (IVM-IVF) are basic techniques for a number of oocyte- or embryo-related technologies. The practical aspects for pig oocyte IVM-IVF have been reviewed, while the molecular mechanisms underlying oocyte meiotic maturation and fertilization have not been well summarized, although accumulating data have been obtained in recent one decade. This review will focus on what is known about the molecular mechanisms of porcine oocyte maturation and fertilization such as first meiosis resumption, meiotic spindle assembly, second meiosis metaphase (MII) arrest during oocyte maturation, sperm-egg recognition and fusion, sperm acrosome reaction, second meiosis resumption, sperm chromatin decondensation, and pronucleus formation during fertilization, as well as the establishment of polyspermy block.  相似文献   

Sequence and analysis of genomic segment A and B of very virulent infectious bursal disease virus isolated from China     

Sun JH  Lu P  Yan YX  Hua XG  Jiang J  Zhao Y 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2003,50(3):148-154

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以胞质雄性不育系配制的早熟秋甘蓝新品种‘中甘22''   总被引：2，自引：1，他引：1  

方智远  刘玉梅  杨丽梅  王晓武  庄木  张扬勇  孙培田 《园艺学报》2003,30(6):761-761,T002

‘中甘22’甘蓝以胞质雄性不育系CMS8180为母本,自交系7014为父本配制而成。该一代杂种秋季种植早熟性好,定植到收获约60d;叶球单球质量1．75kg,抗病毒病和黑腐病,不易裂球,品质优,适于华北、东北、西北地区早秋种植。  相似文献   

Efficacy of live virus vaccines against infectious laryngotracheitis assessed by polymerase chain reaction-restriction fragment length polymorphism     

Han MG  Kim SJ 《Avian diseases》2003,47(2):261-271

The efficacy of four different commercial live vaccines (vaccines A, B, C, and D) against the infectious laryngotracheitis virus (ILTV) was assessed in specific-pathogen-free (SPF) chickens. SPF chickens were vaccinated intraocularly at 6 wk old with ILTV live vaccines and were challenged intratracheally with the N91B01 strain of virulent Korean ILTV 2 wk after vaccination. The immunity against ILTV live vaccines was assessed by the incidence of latent infection by the challenge virus in the chickens' tracheas and trigeminal ganglia, the reisolation rate of the challenge virus, and the clinical signs in the chickens challenged with the N91B01 strain of ILTV. The latent infection in chickens was assessed by nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Our data showed that the clinical signs and challenge virus isolation were negative in all chickens receiving four difference commercial ILTV live vaccines. The viral DNA of the vaccine strain, but not that of the challenge virus, was detected in chickens vaccinated with vaccine A by nested PCR-RFLP. The viral DNAs of both the vaccine and challenge strains were detected from chickens vaccinated with vaccines B, C, and D. This study showed that only vaccine A can protect chickens from latent infection with the field virulent ILTV. We speculate that the efficacy of infectious laryngotracheitis live vaccines to protect chickens from latent infection with virulent ILTVs can be assessed by nested PCR-RFLP analysis.  相似文献   

黑杨派新无性系造林试验     

孙丰金  曹帮华  李长华  李爱民  刘秀丽  艾庆杭 《山东林业科技》2002,(2):10-11

用9个黑杨派新无性系在泰安市进行造林试验,其中I107,中林46,W1－13,I108等4个无性系的生长量较大,造林成活率较高。  相似文献   

Effect of L-NAME on pulmonary arterial pressure,plasma nitric oxide and pulmonary hypertension syndrome morbidity in broilers   总被引：4，自引：0，他引：4  

Wang J  Wang X  Xiang R  Sun W 《British poultry science》2002,43(4):615-620

1. Experiments were conducted to evaluate the effect of a synthetic inhibitor of nitric oxide (NO) synthase (L-NAME) on pulmonary arterial pressure (PAP) and pulmonary hypertension syndrome (PHS) morbidity in broilers. 2. In Experiment 1, broilers were infused intravenously with L-NAME, and the mean pulmonary arterial pressure (mean PAP) and plasma NO were measured at 0, 1, 2 and 4 h after the start of infusion. The mean PAP increased and plasma NO was reduced at 1 to 2 h in broilers treated with L-NAME. 3. In Experiment 2, 180 Arbor Acres broilers were evenly divided into three groups: a control group (group C), and two groups exposed to low environmental temperatures and fed a 3, 3, 5-triiodothyronine (T3) supplemented diet alone (group A) or also including 100 ppm L-NAME (group B). 4. The PHS morbidity of group A was higher than for group C but lower than for group B. Plasma endothelin-1 was higher in broilers in groups A and B than in group C. Plasma NO was not significantly lower in broilers of group B when compared with those in group A. 5. The right/total ventricular weight ratio (RV/TV) and mean PAP were higher in groups A and B than in group C, and the RV/TV ratio increased one week earlier in group B than in group A. 6. These results suggest that L-NAME increases broiler PAP by inhibiting the endogenous synthesis of NO, leading to pulmonary hypertension, right ventricular hypertrophy and the increased morbidity of PHS in broilers.  相似文献   

Rapid communication: physical mapping of two bovine microsatellite loci     

Sun HS  Whallon S  Ponce de León FA  Kirkpatrick BW 《Journal of animal science》2002,80(3):868-869

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Switch recombination in fetal porcine thymus is uncoupled from somatic mutation     

Butler JE  Sun J  Weber P  Ford SP  Rehakova Z  Sinkora J  Francis D  Lager K 《Veterinary immunology and immunopathology》2002,87(3-4):307-319

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Geo-referenced spatiotemporal analysis of the urban citrus canker epidemic in Florida     

Gottwald TR  Sun X  Riley T  Graham JH  Ferrandino F  Taylor EL 《Phytopathology》2002,92(4):361-377

ABSTRACT Five areas in urban Miami were identified to study the spread of Xanthomonas axonopodis pv. citri to determine if the practice of removing exposed citrus trees within 38.1 m of trees affected by citrus canker was adequate to curtail further bacterial spread. To accomplish this, 18,769 trees in dooryards were surveyed, geo-referenced by differential global positioning systems (GPS), and assayed for disease severity, age of infection, citrus cultivar, location of infection in tree, and canopy size. For each tree, the date the tree became infected was estimated and used to separate trees into contiguous 30-day categories. For each area studied, distance measurements between focal trees and newly infected trees were calculated for various temporal periods of 30, 60, 90, and 120 days in duration, corresponding to intervals of inspection survey. A visual basic application was used to calculate the distances between each newly diseased tree and all prior focal trees. The nearest distance was used because it was considered the most conservative estimate possible. It is therefore likely to be an underestimate of spread but is a good estimate of the minimum possible distances of spread. For the first four 30-day periods among the five study areas, calculated maximum distances of spread ranged from 12 to 3,474 m, indicating a broad continuum of distance for bacterial spread was possible. Disease increased during the first two-thirds of the time studied and reached an asymptote due to dry conditions in the final one-third of the duration of the study. Cross correlation analysis indicated that disease was best visualized 107 days following rainstorms with wind. Analysis of regional spatial point patterns was performed temporally for each 30-day period via a modified Ripley's K-function. Spatiotemporal analyses between periods over areas larger than previously examined were accomplished via spatiotemporal semivariogram analysis. These methods in combination demonstrated rapid increases in range of spatial dependency and range of spatiotemporal dependency for all study sites. This corresponded to rapid spread of disease across the regions studied in response to rainstorms with wind followed by a "filling in" of disease on remaining noninfected susceptible trees through time by less intense rain events. A stochastic quadratization technique demonstrated that disease incidence and disease severity were not greatly affected by urban host density but were positively correlated to host susceptibility within local 0.25-km(2) quadrats.  相似文献