THE COMPUTED TOMOGRAPHIC APPEARANCE OF ACUTE THORACOLUMBAR INTERVERTEBRAL DISC HERNIATIONS IN DOGS

The appearance of herniated intervertebral disc material in the thoracolumbar vertebral canal was evaluated in 23 dogs using computed tomography (CT). The images were then compared with the myelographic and surgical findings. The normal spinal cord, outlined by epidural fat over intervertebral disc spaces, was of intermediate attenuation on transverse CT images. Herniated disc material was identified in all animals as a heterogeneous hyperattenuating extradural mass. The attenuation of the disc material increased with the degree of mineralization. In seven dogs, the herniated material was only slightly more attenuating than the spinal cord. In these dogs, small fragments of mineralized disc material and significant hemorrhage were found in the epidural space at surgery. In dogs with a long standing history of disc herniations, disc material identified in the vertebral canal had a more hyperattenuating and homogeneous appearance than recently herniated disc material. We conclude that mineralized, herniated disc material and hemorrhage can be identified quickly and safely in dogs using CT.     

Koi herpesvirus and carp oedema virus: Infections and coinfections during mortality events of wild common carp in the United States

Koi herpesvirus (KHV; cyprinid herpesvirus‐3) and carp oedema virus (CEV) are important viruses of common and koi carp (Cyprinus carpio); however, the distribution of these viruses in wild common carp in North America is largely unknown. During the summers of 2017 and 2018, 27 mass mortalities of common carp were reported from four states in the USA (Minnesota, Iowa, Pennsylvania and Wisconsin), the majority of which were distributed across eight major watersheds in southern Minnesota. Samples from 22 of these mortality events and from five clinically healthy nearby carp populations were screened for KHV, CEV and SVCV using real‐time polymerase chain reaction (qPCR). KHV was confirmed in 13 mortality events, CEV in two mortality events and coinfections of KHV/CEV in four mortality events. Nucleotide sequence analysis revealed that the KHV and CEV detected here are closely related to European lineages of these viruses. While molecular detection alone cannot conclusively link either virus with disease, the cases described here expand the known range of two important viruses. This is also the first reported detection of KHV and CEV coinfections in wild carp populations.     

Occurrence,abundance and associations of Topeka shiners (Notropis topeka) in restored and unrestored oxbows in Iowa and Minnesota,USA

相似文献   

Using historical fisheries data to predict tuna distribution within the British Indian Ocean Territory Marine Protected Area,and implications for its management

相似文献   

Migrations and movements of Atlantic tarpon revealed by two decades of satellite tagging

Understanding large‐scale migratory behaviours, local movement patterns and population connectivity are critical to determining the natural processes and anthropogenic stressors that influence population dynamics and for developing effective conservation plans. Atlantic tarpon occur over a broad geographic range in the Atlantic Ocean where they support valuable subsistence, commercial and recreational fisheries. From 2001 through 2018, we deployed 292 satellite telemetry tags on Atlantic tarpon in coastal waters off three continents to document: (a) seasonal migrations and regional population connectivity; (b) freshwater and estuarine habitat utilization; (c) spawning locations; and (d) shark predation across the south‐eastern United States, Gulf of Mexico and northern Caribbean Sea. These results showed that some mature tarpon make long seasonal migrations over thousands of kilometres crossing state and national jurisdictional borders. Others showed more local movements and habitat use. The tag data also revealed potential spawning locations consistent with those inferred in other studies from observations of early life stage tarpon leptocephalus larvae. Our analyses indicated that shark predation mortality on released tarpon is higher than previously estimated, especially at ocean passes, river mouths and inlets to bays. To date, there has been no formal stock assessment of Atlantic tarpon, and regional fishery management plans do not exist. Our findings will provide critical input to these important efforts and assist the multinational community in the development of a stock‐wide management information system to support informed decision‐making for sustaining Atlantic tarpon fisheries.     

Parvoviral enteritis and salmonellosis in raccoons with sudden death

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.     

Living on the edge: Traits of freshwater fish species at risk in Canada

相似文献   

Exploring the interactions between flood defence maintenance works and river habitats: the use of River Habitat Survey data

• 1. More extensive physical management of rivers in response to increasing flood risk, and action to improve the ecological quality of rivers represent two major, and potentially conflicting, challenges.
• 2. Improved understanding of the interactions between flood defence works and habitat structure must be achieved in order to satisfy both of these demands in the context of flood risk management and habitat improvement.
• 3. This paper examines the ‘extensive’ and ‘intensive’ use of data derived from a standardized method of assessing habitat character to explore the effects of flood risk maintenance works on river habitat quality.
• 4. Analysis of the UK River Habitat Survey (RHS) data set reveals some broad trends towards reduced habitat heterogeneity associated with recent flood defence works such as dredging and weed‐cutting.
• 5. These observations correspond with published localized experimental work and suggest that the RHS database can be a useful resource for identifying relationships at relatively broad scales.
• 6. Applying the RHS methodology at finer spatial scales for sites experiencing continuing maintenance reveals contrasting results and highlights some key methodological issues; these include the availability and selection of high quality benchmark conditions, the legacy of past management, lag times associated with maintenance and recovery, and recording of marginal habitat features.
• 7. Small modifications to the RHS method could enable calculation of more detailed habitat indices while maintaining comparability with the national dataset.
• 8. If the issues identified in this paper can be addressed or accounted for, RHS could be an important tool for assessing the relationship between flood defence management and new statutory obligations for ecological improvement.

Copyright © 2009 John Wiley & Sons, Ltd.     

Comparative SAR Evaluations of Annonaceous Acetogenins for Pesticidal Activity

The activities of 44 Annonaceous acetogenins, which were originally isolated by monitoring plant fractionations with the brine shrimp lethality test (BST), were evaluated in the yellow fever mosquito larvae microtiter plate (YFM) assay. The results clearly demonstrate that most acetogenins have pesticidal properties. The structure–activity relationships indicate that the compounds bearing adjacent bis-THF (tetrahydrofuran) rings with three hydroxyl groups are the most potent. Bullatacin ( 1 ) and trilobin ( 7 ) gave the best activities against YFM with LC₅₀ values of 0·10 and 0·67 mg litre^-1, respectively. Compounds showing LC₅₀ values below 1·0 mg litre^-1 in this assay are usually considered significant as new lead candidates for pesticidal development. In the BST, the corresponding LC₅₀ values were 1·6×10^-3 ( 1 ) and 9·7×10^-3 ( 7 ) mg litre^-1. This is the first report of pesticidal structure–activity relationships for a series of Annonaceous acetogenins which are known to act, at least in part, as potent inhibitors of mitochondrial NADH: ubiquinone oxidoreductase. © of SCI.     

Revisiting a central prediction of the Gill Oxygen Limitation Theory: Gill area index and growth performance

The Gill Oxygen Limitation Theory (GOLT) posits that a mismatch in oxygen supply and demand stemming from geometric constraints on gill surface area limits metabolic rate and energy available for biological processes. This theory has been suggested to explain numerous phenomena observed with warming yet is based upon a relationship among maximum size, growth, and gill surface area established over 40 years ago. However, the metric used in this relationship to characterize gill surface area, gill area index, fails to capture the known variability in the scaling of gill surface area and is biased by the sizes at which gills were measured. Here, we revisit a central prediction of the GOLT, asking four key questions that examine limitations in the original relationship. We find that gill area index does indeed explain variation in growth performance across 132 species of fish and this relationship is strikingly similar to the original relationship across 42 species. Yet, we argue that gill area index is not an adequate measure of gill surface area because (1) gill surface area has a non-linear relationship with size and, thus, changes ontogenetically as an individual grows over time and (2) because it is based on mean estimates of both gill surface area and body mass. Indeed, we show that the value of gill area index for a given species is variable depending on how it is calculated. We therefore suggest a pathway forward for assessing whether gill surface area is an important factor in explaining variation in growth performance.