Reproductive ecology of the threatened and endemic freshwater mussel Lampsilis bracteata     

L. Ashley Seagroves  M. Christopher Barnhart  Thom Hardy  Astrid N. Schwalb 《水产资源保护:海洋与淡水生态系统》2019,29(8):1216-1226

The Chlamydomonas genome reveals the evolution of key animal and plant functions   总被引：1，自引：0，他引：1  

Merchant SS  Prochnik SE  Vallon O  Harris EH  Karpowicz SJ  Witman GB  Terry A  Salamov A  Fritz-Laylin LK  Maréchal-Drouard L  Marshall WF  Qu LH  Nelson DR  Sanderfoot AA  Spalding MH  Kapitonov VV  Ren Q  Ferris P  Lindquist E  Shapiro H  Lucas SM  Grimwood J  Schmutz J  Cardol P  Cerutti H  Chanfreau G  Chen CL  Cognat V  Croft MT  Dent R  Dutcher S  Fernández E  Fukuzawa H  González-Ballester D  González-Halphen D  Hallmann A  Hanikenne M  Hippler M  Inwood W  Jabbari K  Kalanon M  Kuras R  Lefebvre PA  Lemaire SD  Lobanov AV 《Science (New York, N.Y.)》2007,318(5848):245-250

Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the approximately 120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella.  相似文献   

Effects of C and N availability and soil-water potential interactions on N₂O evolution and PLFA composition     

Astrid J. Andersen  Søren O. Petersen 《Soil biology & biochemistry》2009,41(8):1726-23

Mitigation of agricultural N₂O emissions via management requires quantitative information about the regulation of the underlying processes. In this laboratory study, short-term evolution of N₂O from repacked soil was determined using an arable sandy loam soil adjusted to three water potentials (−15, −30 or −100 hPa) that were reached by adjustment of partly air-dried soil with nutrient solutions or water; a water retention curve of repacked soil had been determined prior to the incubation experiment. The amendments included a control treatment receiving water (CTL), and aqueous solutions of carbon in the form of glucose (C), ammonium sulfate (N), or both (CN). Rates of CO₂ and N₂O evolution were followed during 14 days. Soil inorganic N and phospholipid fatty acid (PLFA) composition were analyzed by the end of incubation. Across all nutrient treatments, the soil at the lower moisture content (−100 hPa) showed little or no N₂O evolution irrespective of nutrient treatment. Adding glucose alone reduced N₂O evolution relative to CTL. The addition of N alone had no effect on soil respiration, but significantly increased nitrate accumulation and N₂O evolution. The CN treatment resulted in higher respiration than with C amendment alone, but less N₂O evolution than with N alone, at least at −15 and −30 hPa. Whole-soil PLFA fingerprints at the end of incubation reflected the complex response of gaseous emissions. At −15 hPa growth of Gram negative bacteria, probably including denitrifiers, in the CN treatment was indicated by low cyclopropane-to-precursor ratios. At −100 hPa differentiation of branched-chain fatty acids was taken as evidence for an effect of C amendment on Gram positive bacteria. The highest potential for N₂O evolution was observed at the intermediate soil wetness level; the corresponding gas diffusivities indicated that this parameter may be a better predictor of N₂O emissions than water-filled pore space.  相似文献   

Metabolic effects in rapeseed (Brassica napus L.) seedlings after root exposure to glyphosate     

Iben Lykke Petersen  Hans Christian Bruun Hansen  Jens Christian Sørensen 《Pesticide biochemistry and physiology》2007,89(3):220-229

Metabolic effects in rapeseed (Brassica napus L.) seedlings after root exposure to sublethal concentrations of glyphosate were examined in order to evaluate the possibilities of using a response pattern in plants as a measure of exposure to glyphosate through the growth media, more sensitive than the well-known biomarker shikimate. Rapeseed seedlings were grown in hydroponic nutrient solutions containing varying sublethal concentrations of glyphosate (1-50 μM). After 9 days of glyphosate exposure, the shoots of the seedlings were analysed with respect to the effects on selected metabolites downstream from the primary affected metabolite shikimate, which accumulated linearly in response to glyphosate exposure (from 0 to ∼126 μmol/g DW). The selected metabolites analysed, comprising the free amino acids, and the glucosinolates derived therefrom, showed complex patterns in response to glyphosate exposure. Most noteworthy was though that they responded at the lowest concentrations of exposure to glyphosate (1 μM), where no visual effects, decrease in shoot DW or shikimate could be detected, indicating that a biomarker response more sensitive than that of shikimate can be established for plants exposed to glyphosate.  相似文献   

Immunologic phenomena in the effusive form of feline infectious peritonitis   总被引：15，自引：0，他引：15  

N C Petersen  J F Boyle 《American journal of veterinary research》1980,41(6):868-876

The effusive form of feline infectious peritonitis (FIP) was reproduced by injecting 12- to 16-week-old kittens intraperitoneally with a cell-free inoculum derived from the tissues of infected cats. The kittens used for the study were either positive for FIP virus-reacting antibodies before inoculation or they were seronegative. Seropositive kittens were obtained from a cattery where the natural infection was enzootic, and seronegative kittens were obtained from a specific-pathogen-free cattery. Only about half the kittens that were seronegative before inoculation developed disease or serum antibodies to the tissue-derived virus. Seronegative kittens that developed disease showed no signs of illness until 8 to 10 days after inoculation, and they lived for 7 to 14 days after clinical signs appeared. The onset of clinical disease coincided with the appearance of serum antibodies. In contrast, all of the seropositive kittens became ill within 36 to 48 hours after inoculation, and died within 5 to 7 days. If seronegative kittens were treated with immune serum or immunoglobulin (Ig)G, they developed disease with the same frequency, acuteness, and severity as seropositive kittens. Foci of hepatitis and serositis in seropositive kittens contained viral antigen, IgG bound to antigen, and complement. Serum complement activity also decreased several days before death in seropositive kittens inoculated with tissue-derived FIP virus. The temporal relationship of clinical disease and the appearance of serum antibodies, the more acute and severe nature of the disease produced in seropositive kittens, and the presence of antibody and complement in the lesions indicated that effusive FIP is immunologically mediated.  相似文献   

Induced hydrogen ion transport in lipid membranes as origin of toxic effect of pentachlorophenol in an alga     

Ranjith Jayaweera  Richard Petersen  Pavel Smejtek 《Pesticide biochemistry and physiology》1982,18(2):197-204

Pentachlorophenol (PCP) decreases the rate of carbon assimilation in the alga Selenastrum capricornutum. In parallel with the reduction of carbon assimilation in this alga there is a decrease of electrical resistance of lipid membranes and development of negative membrane surface charge. The experimental results suggest that PCP toxicity to algae is due to adsorption of negatively charged PCP ions at the membrane surface that act as carriers of hydrogen ion across the membrane. This protonophoretic action of PCP causes the decrease of membrane electrical resistance and the dissipation of hydrogen ion electrochemical potential gradients across cellular and subcellular membranes, which reduces the ability of algae to assimilate carbon.  相似文献   

Observations on the Presence and Concentration of Natural Antibodies in Colostrum          下载免费PDF全文

M. Sarwar  B. Campbell    W. E. Petersen 《Canadian journal of veterinary research》1964,28(7):157-160

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Rapid brain cooling in intubated pigs through nasal flushing with oxygen: prevention of brain hyperthermia     

Einer-Jensen N  Khorooshi MH  Petersen MB  Svendsen P 《Acta veterinaria Scandinavica》2001,42(4):459-464

Local cooling of the brain by the respiratory air is found in many animal species. The mechanism is based on cooling of the nasal vein blood and heat transfer in the cavernous sinus/carotid artery complex and is therefore not active in anaesthetised, intubated animals. The present experiment was made to investigate the effects of oxygen flushing of the nasal cavities in such animals. Nine anaesthetised, intubated male pigs were used. The temperatures in the third ventricle and rectum were measured continuously. Oxygen was infused into the nasal cavities during 10 min periods interrupted by 10 min without flow. The nasal oxygen flow constantly induced a rapid, reversible and flow dependant decrease in brain temperature: 0.25 degree C +/- 0.04, (n = 2) (mean +/- SD, n) at < 4 l/min; 1.35 degrees C +/- 0.78, (n = 20) at 4-6 l/min; and 1.44 degrees C +/- 0.62, (n = 6) at > 6 l/min. The ventricle temperature decreased 0.59 degree C +/- 0.23, (n = 8) when the animals were transferred to spontaneous respiration and the tracheal tube removed. It may be possible to protect the brain in intubated animals and humans from heat-induced damages by establishment of nasal flushing.  相似文献   

Application of acute phase protein measurements in veterinary clinical chemistry   总被引：1，自引：0，他引：1  

Petersen HH  Nielsen JP  Heegaard PM 《Veterinary research》2004,35(2):163-187

The body's early defence in response to trauma, inflammation or infection, the acute phase response, is a complex set of systemic reactions seen shortly after exposure to a triggering event. One of the many components is an acute phase protein response in which increased hepatic synthesis leads to increased serum concentration of positive acute phase proteins. The serum concentration of these acute phase proteins returns to base levels when the triggering factor is no longer present. This paper provides a review of the acute phase proteins haptoglobin, C-reactive protein and serum amyloid A and their possible use as non-specific indicators of health in large animal veterinary medicine such as in the health status surveillance of pigs at the herd level, for the detection of mastitis in dairy cattle and for the prognosis of respiratory diseases in horses.  相似文献   

Parasite population dynamics in pigs infected with Trichuris suis and Oesophagostomum dentatum     

Heidi Huus Petersen  Annette Andreasen  Helene Kringel  Allan Roepstorff  Stig M. Thamsborg 《Veterinary parasitology》2014,199(1-2):73-80

The aim of the present study was to investigate the population dynamics and potential interactions between Trichuris suis and Oesophagostomum dentatum in experimentally co-infected pigs, by quantification of parasite parameters such as egg excretion, worm recovery and worm location. Forty-eight helminth naïve pigs were allocated into four groups. Group O was inoculated with 20 O. dentatum L₃/kg/day and Group T with 10 T. suis eggs/kg/day. Group OT was inoculated with both 20 O. dentatum L₃/kg/day and 10 T. suis eggs/kg/day, while Group C was kept as an uninfected control group. All inoculations were trickle infections administered twice weekly and were continued until slaughter. Faecal samples were collected from the rectum of all pigs at day 0, and twice weekly from 2 to 9 weeks post first infection (wpi). Six pigs from each group were necropsied 5 wpi and the remaining 6 pigs from each group were necropsied 10 wpi. The faecal egg counts (FEC) and total worm burdens of O. dentatum were dramatically influenced by the presence of T. suis, with significantly lower mean FECs and worm burdens at 5 and 10 wpi compared to single infected pigs. Furthermore, in the presence of T. suis we found that O. dentatum was located more posteriorly in the gut. The changes in the Trichuris population were less prominent, but faecal egg counts, worm counts 5 wpi (57% recovered vs. 39%) and the proportion of infected animals at 10 wpi were higher in Group OT compared to Group T. The location of T. suis was unaffected by the presence of O. dentatum. These results indicate an antagonistic interaction between T. suis and O. dentatum which is dominated by T. suis.  相似文献