Trends in Chinook salmon spawner abundance and total run size highlight linkages between life history,geography and decline     

William I. Atlas  Matthew R. Sloat  William H. Satterthwaite  Thomas W. Buehrens  Charles K. Parken  Jonathan W. Moore  Nathan J. Mantua  Jon Hart  Anna Potapova 《Fish and Fisheries》2023,24(4):595-617

Chinook salmon (Oncorhynchus tshawytscha, Salmonidae) are foundational to social-ecological systems of the Northeast Pacific Rim and exhibit a rich diversity of life histories including in their adult migration timing, age at critical life-history transitions and marine feeding distributions. In recent decades Chinook have experienced declines across much of their native range; however, changes in productivity and abundance have rarely been evaluated in relation to life-history variation. To understand trends in Chinook salmon production, and how they are related to life history, we compiled time series data from the Fraser River to the Sacramento River on total run size (pre-fishery abundance) and escapement (post-fishery spawner abundance) and fit time series models to estimate trends across this bioregion. Our analysis revealed that most Chinook populations are declining, with negative trends in escapement (57 of 79) and total run (16 of 23) size. Trends were most acutely negative for interior spring Chinook in the Fraser, Columbia and Snake Rivers and most populations in California. Summer and fall Chinook had mixed trends, with several summer and fall upriver bright populations in the interior Columbia and Fraser exhibiting increases in abundance from the 1990s to 2019. Our research reveals widespread declines of this important species, but local complexity in trends that are mediated by population-level life history, migratory behaviours and watershed-scale restoration actions. Understanding linkages between life histories and resilience should inform rebuilding efforts for Chinook salmon and highlight the need to conserve intraspecific biodiversity.  相似文献   

An evaluation of immunofluorescence and PCR methods for detection of rabies in archival Carnoy-fixed, paraffin-embedded brain tissue.     

K Kulonen  M Fekadu  S Whitfield  C K Warner 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1999,46(3):151-155

Direct immunofluorescence and PCR detection methods were compared for sensitivity in evaluating the rabies status of archival specimens of Carnoy-fixed, paraffin-embedded brain tissue. The material consisted of 23 samples obtained during a rabies outbreak in Finland in 1988, and one sample isolated from a bat researcher who died of rabies in Finland in 1985. These results were compared with the original diagnoses performed on the fresh tissues. The immunofluorescence assay detected 100% (12/12) of the rabies-positive archival cases. A PCR assay designed to detect a 139-bp target near the 5' end of the rabies nucleoprotein gene also detected 100% (12/12) of the samples identified as positive in the fresh tissue specimens. A PCR assay designed to detect a 304-bp target spanning the 139-bp target of the first assay detected only 67% (8/12) of the original cases. No false positives were recorded. Both immunofluorescence detection of antigen and PCR detection of a short region of the nucleoprotein gene are useful in determining the rabies status of fixed, paraffin embedded (archival) material.  相似文献   

Familial Ventricular Arrhythmias in Boxers   总被引：7，自引：0，他引：7  

Kathryn M. Meurs  Alan W. Spier  Matthew W. Miller  Linda Lehmkuhl  Jeffrey A. Towbin 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1999,13(5):437-439

The purposes of this study were to evaluate families of Boxers with ventricular arrhythmias to determine whether this disorder is a familial trait and, if so, to determine the mode of inheritance. Eighty-two Boxers were evaluated by physical examination, electrocardiogram, echocardiogram, and 24-hour ambulatory electrocardiogram. Dogs were considered affected if at least 50 premature ventricular complexes (PVCs) were observed during a 24-hour period. All dogs were at least 6 years of age at evaluation. Complete cardiovascular examinations were performed on dogs from 6 extended families. The 2 most complete pedigrees were used to determine the pattern of inheritance. The number of PVCs observed during a 24-hour period in affected dogs ranged from 112 to 4,894 (mean +/- SD, median; 1,309 +/- 2,609, 1,017). The number of PVCs observed during a 24-hour period in the unaffected dogs ranged from 0 to 16 (7 +/- 10, 12). Pedigree evaluation was performed to determine pattern of inheritance. An autosomal dominant pattern was determined to be most likely because a sex predisposition was not observed, affected individuals were observed in every generation, and 2 affected individuals produced unaffected offspring. We conclude that familial ventricular arrhythmias is inherited as an autosomal dominant trait in some Boxers.  相似文献   

The influence of defoliation height on dry-matter partitioning and CO₂ exchange of perennial ryegrass miniature swards     

A. Hernández Garay  C. Matthew  & J. Hodgson 《Grass and Forage Science》2000,55(4):372-376

This study investigated the effects of defoliation intensity on the above- and below-ground plant mass, rates of CO₂ exchange and leaf appearance rate of ryegrass miniature swards maintained at constant cutting height ranging from 20 mm to 160 mm for 5 months. Total plant mass, above-ground herbage mass and root mass increased as cutting height increased from 20 to 120 mm. Further increase in cutting height did not increase total plant mass or its components. Leaf appearance rate and photosynthesis per unit of leaf dry matter (DM) decreased as defoliation height increased from 20 to 160 mm. Gross and net CO₂ uptake per unit soil surface area increased with cutting height to 120 mm. Further increase in cutting height to 160 mm decreased gross and net CO₂ uptake and herbage harvested. A multivariate canonical discriminant analysis indicated different responses of root and shoot mass to cutting height and a reduction in CO₂ uptake rate at the 160 mm cutting height. The implications of those responses to defoliation management of forage plants are discussed.  相似文献   

Gas chromatographic detection of the mycotoxin zearalenone in blood serum     

H L Trenholm  R Warner  E R Farnworth 《Journal of the Association of Official Analytical Chemists》1980,63(3):604-611

A sensitive gas chromatographic method for the quantitative analysis of zearalenone in blood serum is described. Zearalenone is eluted from blood serum by column chromatography followed by base-acid extraction with dichloromethane as the organic phase. After epicoprostanol (internal standard) is added, the sample is evaporated to dryness, derivatized, and injected onto the gas chromatographic column. A number of silylating agents and reaction conditions were investigated. Derivatizing zearalenone with N-methyl-N-trimethylsilyltrifluoroacetamide in the presence of acetone at room temperature for at least 2 hr gave best results. Sensitivity limit is < 0.5 ng injected, equivalent to 100 ng zearalenone/mL blood serum. A linear standard curve is observed when 0.5-30 ng zearalenone derivative is injected onto the Perkin-Elmer gas chromatograph. For quantitation, a standard curve is prepared by plotting amounts of zearalenone (ng) injected vs. ratios for peak areas of zearalenone and epicoprostanol derivatives. The internal standard procedure improves the precision by minimizing variations in sample injections and detector response. Percent recovery from blood serum is 68-75 in the range of 1.6-8.0 micrograms zearalenone/mL blood.  相似文献   

Rapid method for the quantitative measurement of numerous pharmaceutically important amines     

W R Matthew  H C Browne  J B Weber 《Journal of the Association of Official Analytical Chemists》1972,55(4):789-793

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Evaluation of partial replacement of live and fresh feeds with a formulated diet and the influence of weaning <Emphasis Type="Italic">Panulirus ornatus</Emphasis> phyllosomata onto a formulated diet during early ontogeny     

Matthew D. Johnston  Danielle J. Johnston  Clive M. Jones 《Aquaculture International》2008,16(1):33-47

We have evaluated the potential of a formulated diet as a replacement for live and fresh feeds for 7-day post-hatch Panulirus ornatus phyllosomata and also investigated the effect of conditioning phyllosomata for 14–21 days on live feeds prior to weaning onto a 100% formulated diet. In the first trial, the highest survival (>55%) was consistently shown by phyllosomata fed a diet consisting of a 50% combination of Artemia nauplii and 50% Greenshell mussel, followed by phyllosomata fed 50% Artemia nauplii and 50% formulated diet and, thirdly, by those receiving 100% Artemia nauplii. The second trial assessed the replacement of on-grown Artemia with proportions of formulated diet and Greenshell mussel that differed from those used in trial 1. Phyllosomata fed a 75% combination of formulated diet and 25% on-grown Artemia and 50% on-grown Artemia and 50% Greenshell mussel consistently showed the highest survival (>75%). Combinations of Greenshell mussel and formulated diet resulted in significantly (P < 0.05) reduced survival. In trial 3, phyllosomata were conditioned for 14, 18 or 21 days on Artemia nauplii prior to weaning onto a 100% formulated diet, which resulted in survival rates that were negatively related to the duration of feeding Artemia nauplii. In the final trial, phyllosomata were conditioned for 14 days on live on-grown Artemia prior to weaning onto one of three formulated diets (one diet with 44% CP and two diets with 50%). Phyllosomata fed a 44% CP diet consistently showed the highest survival (>35%) among all treatments, while those fed a 50%-squid CP diet showed a significant (P < 0.05) increase in mortality at day 24. The results of these trials demonstrate that hatcheries can potentially replace 75% of live on-grown Artemia with a formulated diet 7 days after hatch. The poor performance associated with feeding combinations of Greenshell mussel and formulated diet, and 100% formulated diet as well as conditioning phyllosomata for 14–21 days on live feeds prior to weaning onto a formulated diet highlights the importance of providing Artemia to stimulate feeding.  相似文献   

Marking live feeds with inert metal oxides for fish larvae feeding and nutrition studies     

Matthew A Cook  Ronald B Johnson  Pete Nicklason  Harold Barnett  & Michael B Rust 《Aquaculture Research》2008,39(4):347-353

Yttrium oxide (Y₂O₃), ytterbium oxide (Yb₂O₃), lanthanum oxide (La₂O₃) and dysprosium oxide (Dy₂O₃) were evaluated as potential live feed markers for feeding and nutrition studies with fish larvae, by determining the uptake and depletion of markers over time in two trials, and quantifying ingestion of Y₂O₃‐marked rotifers (Branchionus plicatilis) by Atlantic cod (Gadus morhua) in a third trial. In the first two trials, Artemia nauplii and rotifers quickly took up markers within 10 min to concentrations useful for nutrition studies (>2% dry weight). There was no significant difference (P>0.05) among temperatures in depletion of markers (10, 15, 20 °C) with Artemia or rotifers. Depletion from rotifers was not significantly different (P>0.05) between 5 and 20 min nor between 5 and 30 min for Artemia when marked at a concentration of 50 mg of marker per litre of seawater. In the second trial, rotifers and Artemia were marked with a higher concentration (250 mg L^?1) and allowed to deplete for a longer time (90 min). In the third trial, visual estimates of Artemia consumed by Atlantic cod larvae were similar to consumption estimates determined by analysis of Y₂O₃‐marked Artemia using inductively coupled plasma optical emission spectroscopy (r²=0.77).  相似文献   

Phosphorus speciation in cultivated organic soils revealed by P K‐edge XANES spectroscopy     

Frank Schmieder  Jon Petter Gustafsson  Wantana Klysubun  Franz Zehetner  Matthew Riddle  Holger Kirchmann  Lars Bergstrm 《植物养料与土壤学杂志》2020,183(3):367-381

Cultivated organic soils make a significant contribution to phosphorus (P) leaching losses from agricultural land, despite occupying a small proportion of cultivated area. However, less is known about P mobilisation processes and the P forms present in peat soils compared with mineral soils. In this study, P forms and their distribution with depth were investigated in two cultivated Histosol profiles, using a combination of wet chemical extraction and P K‐edge X‐ray absorption near‐edge structure (XANES) spectroscopy. Both profiles had elevated P content in the topsoil, amounting to around 40 mmol kg^?1, and P speciation in both profiles was strongly dominated by organic P. Topsoils were particularly rich in organic P (P‐org), with relative proportions of up to 80%. Inorganic P in the profiles was almost exclusively adsorbed to surface reactive aluminium (Al) and iron (Fe) minerals. In one of the pro‐files, small contributions of Ca‐phosphates were detected. A commonly used P saturation index (PSI) based on ammonium‐oxalate extraction indicated a low to moderate risk of P leaching from both profiles. However, the capacity of soil Al and Fe to retain P in organic soils could be reduced by high competition from organic compounds for sorption sites. This is not directly accounted for in PSI and similar indices. Accumulation of P‐org in the topsoil may be attributable by microbial peat decomposition and transformation of mineral fertiliser P by both microbiota and crops. Moreover, high carbon–phosphorus ratio in the surface peat material in both profiles suggests reduced net mineralisation of P‐org in the two soils. However, advancing microbial peat decomposition will eventually lead to complete loss of peat horizons and to mineralisation of P‐org. Hence, P‐org in both profiles represents a huge potentially mobilised P pool.  相似文献   

Hysteretic adsorption and desorption of hydrogen by nanoporous metal-organic frameworks     

Zhao X  Xiao B  Fletcher AJ  Thomas KM  Bradshaw D  Rosseinsky MJ 《Science (New York, N.Y.)》2004,306(5698):1012-1015

Adsorption and desorption of hydrogen from nanoporous materials, such as activated carbon, is usually fully reversible. We have prepared nanoporous metal-organic framework materials with flexible linkers in which the pore openings, as characterized in the static structures, appear to be too small to allow H2 to pass. We observe hysteresis in their adsorption and desorption kinetics above the supercritical temperature of H2 that reflects the dynamical opening of the "windows" between pores. This behavior would allow H2 to be adsorbed at high pressures but stored at lower pressures.  相似文献