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1.
Milk vetch dwarf virus (MDV) is an important member of the genus Nanovirus and is transmitted by the aphid Aphis craccivora. MDV has multiple single-stranded DNA genome components, each approximately 1 kb, and two or three alpha-satellite molecules. It mainly infects plants of the legume family Fabaceae. Recently, papaya (Carica papaya) collected in Yesan, South Korea, displaying symptoms of leaf yellowing and dwarfism, was identified as a new host for MDV. To examine the geographical distribution of MDV, papaya samples with symptoms were harvested in South Korea, Vietnam, and Taiwan in August 2018, along with tomato and pepper samples grown in adjacent fields in Vietnam. The results revealed the presence of MDV not only in papaya but also in pepper and tomato. This MDV infection in members of the Solanaceae family was confirmed by Southern blot hybridization performed using a PCR product of segment S as a probe. Based on sequence analysis of three MDV components (M, S, and C3), we verified the presence of three different isolates of MDV in these three countries and homology between sequences of isolates from papaya and from members of the Solanaceae from Vietnam. Taken together, our results clearly demonstrate MDV infection in Vietnam and Taiwan for the first time and confirm that MDV can infect economically important pepper and tomato.  相似文献   
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Sixty-nine intestinal spirochetes isolated from pigs and poultry in eastern Australia were selected to evaluate the effectiveness of a species-specific PCR-based restriction fragment length polymorphism (RFLP) analysis of the Brachyspira nox gene. For comparative purposes, all isolates were subjected to species-specific PCRs for the pathogenic species Brachyspira hyodysenteriae and Brachyspira pilosicoli, and selected isolates were examined further by sequence analysis of the nox and 16S ribosomal RNA genes. Modifications to the original nox-RFLP method included direct inoculation of bacterial cells into the amplification mixture and purification of the PCR product, which further optimized the nox-RFLP for use in a veterinary diagnostic laboratory, producing sufficient product for both species identification and future comparisons. Although some novel profiles that prevented definitive identification were observed, the nox-RFLP method successfully classified 45 of 51 (88%) porcine and 15 of 18 (83%) avian isolates into 5 of the 6 recognized species of Brachyspira. This protocol represents a significant improvement over conventional methods currently used in veterinary diagnostic laboratories for rapid specific identification of Brachyspira spp. isolated from both pigs and poultry.  相似文献   
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OBJECTIVE: To characterize generation of reactive oxygen species (ROS) by equine spermatozoa. SAMPLE POPULATION: Multiple semen samples collected from 9 stallions. PROCEDURE: Equine spermatozoa were separated from seminal plasma on a discontinuous polyvinylpyrrolidone (PVP)-coated silica gradient and resuspended in a modified Tyrode albumin-lactate-pyruvate medium. Amount of hydrogen peroxide (H2O2) generated was assayed by use of a 1-step fluorometric assay, using 10-acetyl-3,7-dihydroxyphenoxazine as a probe for detection of H2O2 in a microplate assay format. Concentration of H2O2 was determined by use of a fluorescence microplate reader. RESULTS: Amount of H2O2 generated increased significantly with time and spermatozoa concentration for live and flash-frozen spermatozoa, and amount of H2O2 generated was significantly greater for flash-frozen than for live spermatozoa. Addition of the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) significantly increased generation of H2O2 by live and flash-frozen spermatozoa. Addition of a calcium ionophore also significantly increased the amount of H2O2 generated by live spermatozoa but did not have an effect on amount of H2O2 generated by flash-frozen spermatozoa. Abnormal equine spermatozoa generated significantly greater amounts of H2O2 than did normal spermatozoa. CONCLUSIONS AND CLINICAL RELEVANCE: Equine spermatozoa generate ROS in vitro, possibly via a NADPH-oxidase reaction. Spermatozoa damaged during flash-freezing or morphologically abnormal spermatozoa generated significantly greater amounts of ROS than did live or morphologically normal spermatozoa. Damaged and abnormal spermatozoa generate greater amounts of ROS that may contribute to reduced fertility or problems related to semen preservation.  相似文献   
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山东省烟草黑胫病菌生理小种初步鉴定   总被引:8,自引:0,他引:8       下载免费PDF全文
1980~1983年在山东6个地(市)16个县共采集分离黑胫病病原菌31个分离物。首先试验证明,游动孢子悬浮液浸根接种方法较好。据此,把山东的黑胫病菌的分离物接种在国外常用的5个鉴别寄主上进行了鉴定试验。通过鉴定,采自山东的31个分离物均属生理小种Ⅰ号。  相似文献   
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We have constructed a physical map of the human genome by using a panel of 90 whole-genome radiation hybrids (the TNG panel) in conjunction with 40,322 sequence-tagged sites (STSs) derived from random genomic sequences as well as expressed sequences. Of 36,678 STSs on the TNG radiation hybrid map, only 3604 (9.8%) were absent from the unassembled draft sequence of the human genome. Of 20,030 STSs ordered on the TNG map as well as the assembled human genome draft sequence and the Celera assembled human genome sequence, 36% of the STSs had a discrepant order between the working draft sequence and the Celera sequence. The TNG map order was identical to one of the two sequence orders in 60% of these discrepant cases.  相似文献   
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宝交早生草莓在0℃下自然降氧贮藏10 d,好果率84%,商品率达98%。用10%CO_2处理可将草莓在0℃的贮藏时间延长到20 d,好果率和商品率均为94%,CO_2浓度超过20%会使草莓产生酒精味。SO_2慢性释放剂处理也有较好的防腐效果。  相似文献   
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The orb web is a spectacular evolutionary innovation that enables spiders to catch flying prey. This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties. We used silk gland expression libraries to address a long-standing controversy concerning the evolution of the orb-web architecture. Contrary to the view that the orb-web design evolved multiple times, we found that the distribution and phylogeny of silk proteins support a single, ancient origin of the orb web at least 136 million years ago. Furthermore, we substantially expanded the repository of silk sequences that can be used for the synthesis of high-performance biomaterials.  相似文献   
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