浅议绿色奥运给承德种苗业带来的发展机遇

分析了承德种苗业面临的机遇,提出了承德种苗业存在的问题和发展对策。     

RS技术在土地详查中的应用研究

本文针对徐州市土地调查及城乡一体化地籍管理信息系统基础建设的现状,按照国土资源部第二次土地详查总体要求提出了徐州市土地二次详查总体方案,并结合3S技术的进展探讨了RS技术在徐州市二次土地详查中应用的技术路线及关键技术.     

2007年棉田主要病虫害发生发展规律及综防经验

本文介绍了新疆阿克苏地在2007年棉田主要病虫害发生和综合防治.     

Effect of diet with thiram on liver antioxidant capacity and tibial dyschondroplasia in broilers

1. An experiment was conducted to study the effect of thiram on liver antioxidant capacity and incidence of tibial dyschondroplasia in broilers. 2. One hundred and twenty Avian commercial broilers were allotted at random to three treatments: control group, low thiram group (50 mg/kg) and high thiram group (100 mg/kg). 3. Blood samples were collected to determine the activity of AST (aspartate aminotransferase). At the end of the trial, broilers were killed and liver samples were collected to determine the activity of SOD (superoxide dismutase), GSH-Px (glutathione peroxidase) and MDA (malondialdehyde) content, while the right proximal tibiotarsi were dissected in longitudinal section for assessment of tibial dyschondroplasia (TD) incidence and TD score. 4. The results showed that thiram increased the incidence of TD and TD scores, increased serum AST activity and MDA content of liver, and decreased the activity of SOD and GSH-Px in the liver. 5. They suggest that thiram causes TD in broilers by reducing liver antioxidation capability and damaging liver function; this may be one of the mechanisms by which thiram causes TD in broilers.     

Prevalence of virulence genes in Escherichia coli strains recently isolated from young pigs with diarrhea in the US

Enterotoxigenic Escherichia coli (ETEC)-associated post-weaning diarrhea (PWD) is economically one of the most important diseases for the swine industry. Porcine ETEC strains typically express K88 or F18 fimbria and heat-labile (LT) and/or heat-stable (STa, STb) enterotoxins. However, recent studies indicate that EAST1 toxin, adhesin involved in diffuse adherence (AIDA-I) and porcine attaching and effacing-associated factor (paa) may also be expressed by ETEC strains associated with diarrhea. To better understand the virulence factors of E. coli strains that cause PWD, we applied PCR to screen for K88, F18, F41, 987P and K99 fimbrial genes; LT, STa, STb, Stx2e and EAST1 toxic genes; and AIDA-I, paa and EAE adhesin genes in E. coli strains recently isolated from young pigs with PWD in the US. Of 304 E. coli isolates from diarrheic pigs submitted for testing, 175 (57.6%) strains possessed fimbrial genes: K88 (64.6%), F18 (34.3%), F41 (0.57%), K99 (0.57%), 987P (0); toxin genes: LT (57.7%), STb (72.6%), STa (27.4%), STx2e (17.4%), EAST1 (35%); and adhesin genes: AIDA-I (26.9%), paa (60%), EAE (1.1%). All toxin genes except the EAST1 toxin gene, were almost exclusively associated with K88+ or F18+ isolates, and most of these isolates carried multiple toxin genes. The non-fimbrial adhesin paa was found present in over half of the K88+ isolates. A total of 129 (42%) isolates carried no fimbrial genes, including 66 (21.7%) isolates that did not have any of the above virulence genes. These results suggest a broad array of virulence genes associated with PWD in pigs.     

Safety of an attenuated West Nile virus vaccine, live Flavivirus chimera in horses

REASON FOR PERFORMING STUDY: West Nile virus (WNV) infection is endemic and able to cause disease in naive hosts. It is necessary therefore to evaluate the safety of new vaccines. OBJECTIVES: To establish: 1) the safety of a modified live Flavivirus/West Nile virus (WN-FV) chimera by administration of an overdose and testing for shed of vaccine virus and spread to uninoculated sentinel horses; 2) that this vaccine did not become pathogenic once passaged in horses; and 3) vaccine safety under field conditions. METHODS: There were 3 protocols: 1) In the overdose/shed and spread study, horses were vaccinated with a 100x immunogenicity overdose of WN-FV chimera vaccine and housed with sentinel horses. 2) A reversion to virulence study, where horses were vaccinated with a 20x immunogenicity overdose of WN-FV chimera vaccine. Horses in both studies were evaluated for abnormal health conditions and samples obtained to detect virus, seroconversion and dissemination into tissues. 3) In a field safety test 919 healthy horses of various ages, breeds and sex were used. RESULTS: Vaccination did not result in site or systemic reactions in either experimental or field-injected horses. There was no shed of vaccine virus, no detection of vaccine virus into tissue and no reversion to virulence with passage. CONCLUSIONS: WN-FV chimera vaccine is safe to use in horses with no evidence of ill effects from very high doses of vaccine. There was no evidence of reversion to virulence. In addition, administration of this vaccine to several hundred horses that may have been previously exposed to WNV or WNV vaccine resulted in no untoward reactions. POTENTIAL RELEVANCE: These studies establish that this live attenuated Flavivirus chimera is safe to use for immunoprophylaxis against WNV disease in horses.     

Efficacy, duration, and onset of immunogenicity of a West Nile virus vaccine, live Flavivirus chimera, in horses with a clinical disease challenge model

REASON FOR PERFORMING STUDY: West Nile virus (WNF) is a Flavivirus responsible for a life-threatening neurological disease in man and horses. Development of improved vaccines against Flavivirus infections is therefore important. OBJECTIVES: To establish that a single immunogenicity dose of live Flavivirus chimera (WN-FV) vaccine protects horses from the disease and it induces a protective immune response, and to determine the duration of the protective immunity. METHODS: Clinical signs were compared between vaccinated (VACC) and control (CTRL) horses after an intrathecal WNV challenge given at 10 or 28 days, or 12 months post vaccination. RESULTS: Challenge of horses in the immunogenicity study at Day 28 post vaccination resulted in severe clinical signs of WNV infection in 10/10 control (CTRL) compared to 1/20 vaccinated (VACC) horses (P<0.01). None of the VACC horses developed viraemia and minimal histopathology was noted. Duration of immunity (DPI) was established at 12 months post vaccination. Eight of 10 CTRL exhibited severe clinical signs of infection compared to 1 of 9 VACC horses (P<0.05). There was a significant reduction in the occurrence of viraemia and histopathology lesion in VACC horses relative to CTRL horses. Horses challenged at Day 10 post vaccination experienced moderate or severe clinical signs of WNV infection in 3/3 CTRL compared to 5/6 VACC horses (P<0.05). CONCLUSIONS: This novel WN-FV chimera vaccine generates a protective immune response to WNV infection in horses that is demonstrated 10 days after a single vaccination and lasts for up to one year. POTENTIAL RELEVANCE: This is the first USDA licensed equine WNV vaccine to utilise a severe challenge model that produces the same WNV disease observed under field conditions to obtain a label claim for prevention of viraemia and aid in the prevention of WNV disease and encephalitis with a duration of immunity of 12 months.     

An 8bp indel in exon 1 of Ghrelin gene associated with chicken growth

Ghrelin, acts as the endogenous ligand for growth hormone secretagogues receptor (GHS-R), is a novel growth hormone (GH) releasing peptide with reported effects on food intake in chickens. In this study, an 8 bp indel polymorphism in exon 1 of the chicken Ghrelin (cGHRL) gene was genotyped in a F(2) designed full-sib population to analyze its associations with chicken growth and carcass traits. Later, mRNA level in the proventriculus was determined by real-time PCR to reveal the expression feature of cGHRL gene. Result showed that this 8 bp indel was significantly associated with body weight at the age of 28 days (BW28) and 56 days (BW56), eviscerated weight (EW) and leg muscle weight (LMW) (P<0.05), highly significantly associated with hatch weight (HW), BW14, 21, 35, 42, 49, 90 and body length (BL), dressed weight (DW), eviscerated weight with giblet (EWG), wing weight (WW), breast muscle weight (BMW) and head and neck weight (HNW) (P<0.01). Meanwhile, A allele (with 'CTAACCTG') was positive for chicken growth as individuals with AA genotype had the highest value of all traits. Analysis on cGhrelin mRNA level revealed that it differed significantly among individuals with three genotypes (P<0.05). Individuals with AB genotype had the highest mRNA level, whereas that of AA had the lowest one. It was concluded that this 8 bp indel of cGHRL gene was significantly associated with most body weight and body composition traits, and negative effect of endogenous Ghrelin on chicken growth were indicated by this study.     

Characterization,phylogenetic analyses and pathogenicity of Bipolaris setariae associated with brown stripe disease on sugarcane in Yunnan,China

Brown stripe disease is a severe foliar fungal disease of sugarcane worldwide and is widespread in all sugarcane planting areas in China. Brown stripe is a major disease that seriously affects the output and quality of the sugarcane industry in Yunnan Province, China's second-largest sugar base, while the pathogen of this disease remains not yet fully understood. To address this, we isolated and identified the fungi associated with 68 leaf samples showing typical symptoms of brown stripe from 22 sugarcane varieties in different areas of Yunnan Province. A total of 113 isolates were obtained, which were morphologically similar. Of these, 64 representative isolates were sequenced for the internal transcribed spacer region (ITS), GAPDH and EF-1α loci. All representative isolates grouped with the type strain of Bipolaris setariae in the phylogenetic trees inferred with individual and concatenated sequences of ITS, GAPDH and EF1-α. Pathogenicity test results showed that B. setariae strains were able to induce typical symptoms of brown stripe. The results obtained in this study clarify that only B. setariae is associated with sugarcane brown stripe in Yunnan, China. It is recorded here for the first time as a pathogen causing sugarcane brown stripe in Yunnan, and it is able to infect many major cultivars and new varieties, posing a new threat to the sugar industry in Yunnan Province. In addition, these results provide the scientific basis for the future breeding of disease-resistant varieties and effective prevention and control of sugarcane brown stripe disease.