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排序方式: 共有792条查询结果,搜索用时 15 毫秒
781.
Shannon M. Sermons Benjamin G. Wherley Chenxi Zhang Daniel C. Bowman 《Journal of plant nutrition》2017,40(10):1404-1416
As bermudagrass (Cynodon dactylon (L.) Pers.) transitions from winter dormancy to active growth in spring, nitrogen is essential for new tissue growth. We examined the relative contributions of internally stored nitrogen and that taken up by preexisting and newly produced roots. Field-collected dormant bermudagrass was transferred to a nutrient solution culture system in a growth chamber. Cultures were provided either a non-nitrogen-containing solution or one amended with nitrate labeled with the 15N isotope of nitrogen, which allowed tracking of endogenous and exogenous N pools in all tissues as growth began. Nitrogen in stolon internodes was the largest N source for early growth. Though mass increased at the same rate in both N treatments over 3 weeks of growth, the unfertilized treatment showed early signs of nitrogen deficiency: low tissue N, slowed leaf elongation, and fewer but longer roots. Preexisting roots were active in absorption almost immediately; new roots were produced quickly and had even higher N uptake rates. 相似文献
782.
Chun-Ming Lin Benjamin Hause Deanna Gualtieri Nicholas Robinson 《Journal of veterinary diagnostic investigation》2021,33(6):1172
Eight of 9 juvenile raccoons at a rehabilitation center died without obvious prior clinical signs. Gross changes were unremarkable except for mildly distended intestines. Microscopically, crypt loss, distension, necrosis, and regeneration with intranuclear viral inclusions were observed in the small intestine, with marked lymphoid depletion and necrosis in Peyer patches and mesenteric lymph nodes. Immunohistochemistry with a canine parvovirus antibody showed intensive signals of parvoviral antigens in the crypts and lymphoid germinal centers. Metagenomic sequencing allowed assembly of a complete parvoviral genome with >99% identity to canine parvovirus 2a, as well as Salmonella enterica subsp. enterica. Also, S. enterica subsp. enterica serovar Thompson with multiple antimicrobial resistance was isolated from the intestinal contents. Concurrent infection with parvovirus and Salmonella should be included as a differential diagnosis in raccoons with sudden death. 相似文献
783.
Benjamin R. LaFrentz Julio C. García John P. Shelley 《Journal of fish diseases》2019,42(11):1531-1542
Recent research has identified four distinct genetic groups among isolates of Flavobacterium columnare through multilocus phylogenetic analyses; however, there are no quick methods to determine the genotype of an isolate. The objective of this research was to develop a multiplex PCR to rapidly genotype F. columnare to genetic group. Comparative bacterial genomics was used to identify regions in the genomes unique to each genetic group, and primers were designed to specifically amplify different sized amplicons for each genetic group. The optimized assay was demonstrated to be specific for each genetic group and F. columnare, and no specific amplicons were generated using gDNA from a panel of other Flavobacterium spp. and bacterial fish pathogens. The analytical sensitivity of the assay ranged from 209 to 883 genome equivalents depending on the genetic group. The multiplex PCR was evaluated by genotyping a panel of 22 unknown F. columnare isolates and performing DNA sequencing of the dnaK gene in parallel. The results demonstrated 100% accordance between multiplex PCR results and assignment to genetic group via phylogenetic analysis. The multiplex PCR provides a useful tool for assigning an unknown isolate to genetic group and may be used to determine which genetic groups of F. columnare are circulating and most predominant in different aquaculture industries. 相似文献
784.
The soybean cyst nematode (SCN) Heterodera glycines and the oomycete Phytophthora sojae are among the most damaging pathogens of soybean worldwide. Resistant cultivars are commonly used to manage these diseases. As it is known that the presence of SCN can facilitate the development of other pathogens, it is important to verify if there is a synergistic activity between SCN and P. sojae. The purpose of this study was to evaluate a possible interaction on susceptible and resistant soybean lines. The plants were inoculated with one or both organisms at different stages (5 or 10 days old). Two levels of SCN inoculum (2,000 and 10,000 eggs/plant) and different timing between SCN and P. sojae inoculation (2, 5, or 8 days) were compared. The results on 5-day-old plants showed that SCN did not influence P. sojae development. The resistant cultivar to P. sojae remained effective (0% mortality) and susceptible cultivars exhibited high mortality (100%) in the presence or absence of SCN. Experiments on 10-day-old plants showed that SCN resistance was not affected by the presence of P. sojae. SCN inoculum density and timing of P. sojae infection did not affect the virulence of these pathogens and the efficacy of resistance genes. However, the number of SCN cysts was decreased by more than 50% (p < .001) when P. sojae was coinfesting the susceptible cultivar. This suggests that P. sojae might indirectly influence SCN development by reducing the root mass. This study confirmed that resistant cultivars remain a valid option for the management of P. sojae and SCN. 相似文献
785.
786.
Benjamin T. Jakobek Rebecca C. McOnie Susan L. Fubini Galina Hayes 《The Canadian veterinary journal. La revue veterinaire canadienne》2021,62(12):1292
A 7-month-old Hampshire ram, with no history of trauma or breeding, was referred for treatment of acute, unilateral scrotal swelling. Physical examination revealed a moderately sized, soft, left-sided, non-reducible swelling of the proximal scrotum and mild swelling of the scrotal neck. Ultrasound evaluation of the scrotum revealed morphologically normal testicles and a mild accumulation of free fluid in the left vaginal tunic. Unilateral, laparoscopic inguinal herniorrhaphy under general anesthesia was performed. The herniated omentum was reduced and barbed suture was used to imbricate the internal inguinal ring and the vaginal ring. No recurrence of herniation was reported 5 months after surgery.Key clinical message:Laparoscopic inguinal herniorrhaphy with barbed suture can be a safe and effective means of scrotal hernia resolution in a ram. When performed by a competent surgeon experienced in laparoscopy, this treatment for inguinal and scrotal herniation may minimize post-operative pain, provide a rapid return to function, and preserve normal testicular and scrotal anatomy. 相似文献
787.
Pheng Sengxua Benjamin K. Samson Chay Bounphanousay Sisavanh Xayavong Khamsouk Douangboupha Dome Harnpichitvitaya 《Plant Production Science》2017,20(4):477-484
Genotype by environment (G×E) interactions for grain yield were investigated in 14 rice genotypes across eight rainfed lowland field environments in Lao PDR, in order to identify stable adapted cultivars for improved farmer livelihood and food security. G×E accounted for 20.3% of the total variance, with three vectors from ordination analysis accounting for 75.1% of the G×E-SS, in 6 genotype?×?6 environment groups. PCA1 indicated water-limited yield potential, PCA2 pre-flowering stress and PCA3 post-flowering stress. Genotype groups (G1–G6) differed in adaptation to these environments. G5 (VT450-2 and TSN9) were widely adapted and high-yielding. G6 (TDK11 and TDK37) were also high-yielding, topping the rankings in three environment groups, but yielded less in Phalanxay 2012 and Phalanxay 2011, where their phenology was unstable under stress. Other genotype groups showed specific adaptations, but failed to exceed yields of G5 and G6. Hence, VT450-2 and TSN9 (G5) were the preferred genotypes for rainfed lowland in southern Lao PDR, due to their high and stable grain yields. Stability in flowering time and high yield in rainfall deficit were desirable traits for improved farmer livelihood and food security. 相似文献
788.
Retrospective evaluation of hypersensitivity reactions and anaphylaxis in dogs (2003–2014): 86 cases
789.
Eric S. Torvinen Jeffrey A. Falke Christopher D. Arp Benjamin M. Jones Matthew S. Whitman Christian E. Zimmerman 《Ecology of Freshwater Fish》2023,32(1):166-180
Climate change is occurring rapidly in the Arctic, and an improved understanding of the response of aquatic biota and ecosystems will be important for this data-limited region. Here, we applied biochronology techniques and mixed-effects modelling to assess relationships among growth increments found on lake trout (Salvelinus namaycush) otoliths (N = 49) captured from 13 lakes on the Arctic Coastal Plain of northern Alaska, observed and modelled climate patterns, and individual-level fish and lake characteristics. We found that annual growth varied by year, fish growth slowed significantly as individuals aged, and females grew faster than males. Lake trout had higher growth in flow-through lakes relative to lakes that were perennially or seasonally connected. Annual growth was positively correlated with observed air temperature measurements from a local weather station for the period 1998–2014, but no clear warming trend was evident for this period. Modelled August air temperatures from 1978–2014 predicted lake trout annual growth (root mean squared error = 0.045 mm) and indicated increasing temperatures and annual lake trout growth over the period 1950–2014. This study demonstrated that biochronology techniques can reconstruct recent climate patterns and provide a better understanding of trends in Arctic lake ecosystems under a changing climate. 相似文献
790.
Rachel N. Hofer Allen Lin Benjamin C. House Christopher N. Purvis Bradley J. Harris Steven J. K. Symes David K. Giles 《Journal of fish diseases》2023,46(1):31-45
Aeromonas salmonicida is a Gram-negative bacterium that can infect a wide host range of fish populations, including salmonids and non-salmonids as well as freshwater and marine life. Some strains of A. salmonicida cause the disease furunculosis, which can cause lethargy, intestinal inflammation, ulcers, haemorrhaging and death. The infection is spread through fish-to-fish contact, and the presence of infection can have devastating effects on cultivated fish populations. The purpose of this study was to explore the ability of non-A-layer and A-layer A. salmonicida strains to incorporate polyunsaturated fatty acids (PUFAs) into their lipid profile and test the phenotypic effects thereof. Lipids were extracted from PUFA-exposed cultures and analysed for lipid modification by thin-layer chromatography and ultraperformance liquid chromatography-mass spectrometry, showing A. salmonicida, regardless of A-layer, capable of incorporating all seven of the PUFAs studied. Phenotypic effects were determined through the use of assays that tested for biofilm formation, membrane permeability and cyclic peptide susceptibility. Temperature-dependent effects on biofilm formation were observed, and PUFA exposure showed significant (p < .001) increases in membrane permeability as tested by the uptake of the hydrophobic compounds crystal violet and ethidium bromide. Additionally, some PUFAs elicited modest protection and vulnerability against the membrane-targeting cyclic peptides polymyxin B (PMB) and colistin. The diverse, strain-specific responses to exogenous PUFAs may allude to evolved adaptive strategies that enhance survival, persistence and virulence of non-pathogenic and pathogenic members of bacteria that oscillate between environmental and fish host niches. 相似文献