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1.
Effect of neuropeptides on production of inflammatory cytokines by human monocytes 总被引：60，自引：0，他引：60
Two groups of mediators, the neuropeptides substance P and K and the monocyte-derived cytokines, interact in the neural regulation of immunological and inflammatory responses. Substance P, substance K, and the carboxyl-terminal peptide SP(4-11) induce the release of interleukin-1, tumor necrosis factor-alpha, and interleukin-6 from human blood monocytes. The neuropeptide effects occur at low doses, are specific as shown by inhibition studies with a substance P antagonist, and require de novo protein synthesis. Since monocyte-derived cytokines regulate multiple cellular functions in inflammation and immunity and since neuropeptides can be released from peripheral nerve endings into surrounding tissues, these findings identify a potent mechanism for nervous system regulation of host defense responses. 相似文献
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A dense microbial community develops in the water column of intensive, minimal-exchange production systems and is responsible for nutrient cycling. A portion of the microbial community is associated with biofloc particles, and some control over the concentration of these particles has been shown to provide production benefits. To help refine the required degree of control, this study evaluated the effects of two levels of biofloc management on water quality and shrimp (Litopenaeus vannamei) production in commercial-scale culture systems. Eight, 50 m3 raceways were randomly assigned to one of two treatments: T-LS (treatment-low solids) and T-HS (treatment-high solids), each with four replicate raceways. Settling chambers adjacent to the T-LS raceways had a volume of 1700 L with a flow rate of 20 L min−1. The T-HS raceways had 760 L settling chambers with a flow rate of 10 L min−1. Raceways were stocked with 250 shrimp m−3, with a mean individual weight of 0.72 g, and shrimp were grown for thirteen weeks. Raceways in the T-LS treatment had significantly reduced total suspended solids, volatile suspended solids, and turbidity compared to the T-HS treatment (P ≤ 0.003). The T-LS raceways also had significantly lower nitrite and nitrate concentrations, and the T-HS raceways had significantly lower ammonia and phosphate concentrations (P ≤ 0.021). With the exception of nitrate, there were no significant differences between the change in concentration of water quality parameters entering and exiting the settling chambers in the T-LS versus the T-HS treatment. Nitrate never accumulated appreciably in the T-LS raceways, possibly due to denitrification in the settling chambers, bacterial substrate limitations in the raceways, or algal nitrate assimilation. However, in the T-HS raceways nitrate did accumulate. The T-HS settling chambers returned a significantly lower nitrate concentration and significantly greater alkalinity concentration than what entered them (P ≤ 0.005), indicating that denitrification may have occurred in those chambers. There were no significant differences in shrimp survival, feed conversion ratio, or final biomass between the two treatments. However, shrimp in the T-LS treatment grew at a significantly greater rate (1.7 g wk−1 vs. 1.3 g wk−1) and reached a significantly greater final weight (22.1 g vs. 17.8 g) than shrimp in the T-HS treatment (P ≤ 0.020). The results of this study demonstrate engineering and management decisions that can have important implications for both water quality and shrimp production in intensive, minimal-exchange culture systems. 相似文献
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Shrimp (Litopenaeus vannamei) production and stable isotope dynamics in clear‐water recirculating aquaculture systems versus biofloc systems 
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下载免费PDF全文 Closed recirculating aquaculture systems (RAS) offer advantages over traditional culture methods including enhanced biosecurity, the possibility of indoor, inland culture of marine species year‐round and potential marketing opportunities for fresh, never‐frozen seafood. Questions still remain regarding what type of aquaculture system may be best suited for the closed‐system culture of marine shrimp. In this study, shrimp (Litopenaeus vannamei) were grown in clear‐water RAS and in biofloc‐based systems. Comparisons were made between the system types with respect to water quality, shrimp production and stable isotope dynamics used to determine the biofloc contribution to shrimp nutrition. Ammonia and nitrite concentrations were higher, and shrimp survival was lower in the biofloc systems. Although stable isotope levels indicated that biofloc material may have contributed 28% of the carbon and 59% of the nitrogen in shrimp tissues, this did not correspond with improved shrimp production. Overall, the water column microbial communities in biofloc systems may be more difficult to manage than clear‐water RAS which have external filters to control water quality. Biofloc does seem to offer some nutritional contributions, but exactly how to take advantage of that and ensure improved production remains unclear. 相似文献
4.
Societal Costs of Late Blight in Potato and Prospects of Durable Resistance Through Cisgenic Modification 总被引：6，自引：4，他引：2
A. J. Haverkort P. M. Boonekamp R. Hutten E. Jacobsen L. A. P. Lotz G. J. T. Kessel R. G. F. Visser E. A. G. van der Vossen 《Potato Research》2008,51(1):47-57
In the European Union almost 6 Mha of potatoes are grown representing a value of close to €6,000,000,000. Late blight caused
by Phytophthora infestans causes annual losses (costs of control and damage) estimated at more than €1,000,000,000. Chemical control is under pressure
as late blight becomes increasingly aggressive and there is societal resistance against the use of environmentally unfriendly
chemicals. Breeding programmes have not been able to markedly increase the level of resistance of current potato varieties.
New scientific approaches may yield genetically modified marker-free potato varieties (either trans- and/or cisgenic, the
latter signifying the use of indigenous resistance genes) as improved variants of currently used varieties showing far greater
levels of resistance. There are strong scientific investments needed to develop such improved varieties but these varieties
will have great economic and environmental impact. Here we present an approach, based on (cisgenic) resistance genes that
will enhance the impact. It consists of five themes: the detection of R-genes in the wild potato gene pool and their function related to the various aspects in the infection route and reproduction
of the late blight causing pathogen; cloning of natural R-genes and transforming cassettes of single or multiple (cisgenic) R-genes into existing varieties with proven adaptation to improve their value for consumers; selection of true to the wild
type and resistant genotypes with similar qualities as the original variety; spatial and temporal resistance management research
of late blight of the cisgenic genetically modified (GM) varieties that contain different cassettes of R-genes to avoid breaking of resistance and reduce build-up of epidemics; communication and interaction with all relevant stakeholders
in society and transparency in what research is doing. One of the main challenges is to explain the different nature and possible
biological improvement and legislative repercussions of cisgenic GM-crops in comparison with transgenic GM-crops. It is important
to realize that the present EU Directive 2001/18/EC on GM crops does not make a difference between trans- and cisgenes. These
rules were developed when only transgenic GM plants were around. We present a case arguing for an updating and refinement
of these rules in order to place cisgenic GM-crops in another class of GM-plants as has been done in the past with (induced)
mutation breeding and the use of protoplast fusion between crossable species. 相似文献
5.
Ross Meentemeyer David Rizzo Walter Mark Elizabeth Lotz 《Forest Ecology and Management》2004,200(1-3):195-214
Sudden oak death, caused by the recently described pathogen Phytophthora ramorum, is an emerging forest disease that has reached epidemic levels in coastal forests of central California. We present a rule-based model of P. ramorum establishment and spread risk in California plant communities. The model, which is being used as a management tool to target threatened forests for early-detection monitoring and protection, incorporates the effects of spatial and temporal variability of multiple variables on pathogen persistence. Model predictions are based on current knowledge of host susceptibility, pathogen reproduction, and pathogen transmission with particular regard to host species distribution and climate suitability. Maps of host species distributions and monthly weather conditions were spatially analyzed in a GIS and parameterized to encode the magnitude and direction of each variable's effect on disease establishment and spread. Spread risk predictions were computed for each month of the pathogen's general reproductive season and averaged to generate a cumulative risk map (Fig. 6a and b). The model identifies an alarming number of uninfected forest ecosystems in California at considerable risk of infection by Phytophthora ramorum. This includes, in particular, a broad band of high risk north of Sonoma County to the Oregon border, a narrow band of high risk south of central Monterey County south to central San Luis Obispo County, and scattered areas of moderate and high risk in the Sierra Nevada foothills in Butte and Yuba counties. Model performance was evaluated by comparing spread risk predictions to field observations of disease presence and absence. Model predictions of spread risk were consistent with disease severity observed in the field, with modeled risk significantly higher at currently infested locations than at uninfested locations (P < 0.01, n = 323). Based on what is known about the ecology and epidemiology of sudden oak death, this model provides a simple and effective management tool for identifying emergent infections before they become established. 相似文献
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Barbara D. Brewer MA DVM Stephane F. Clement DVM W. Stephen Lotz BS Ronald Gronwall DVM PhD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1991,5(1):28-33
Urine (U) and serum (S) were obtained every 2 hours during a 12- or 24-hour period from eight healthy 96-hour-old pony or horse foals. Dams' milk samples were obtained concurrently. Urine volume was measured during this 12- or 24-hour period. The mean amount of urine produced was 148 +/- 20 ml/kg/day. Baseline urinalyses were evaluated on all foals at two days of age, before any manipulation. Urine generally was dilute (less than 1.008) but the specific gravity was as high as 1.027 in one normal foal. Continuous (12 or 24 hour) urinary catheterization resulted in bacteriuria but not white blood cells in the urine. Prolonged catheterization did not cause foals to become febrile or exhibit clinical signs of cystitis or other illness. Urinary electrolyte excretion, urinary electrolyte clearances, and fractional electrolyte excretions (FE) were measured. When compared with normal values reported in adult horses, excretion, clearance, and FE were similar for sodium (Na) but higher for potassium (K), phosphorus (P), and calcium (Ca). There were no significant differences between data collected during different time periods, and it was concluded that the use of single sample urine/serum estimates of fractional excretion in the neonatal foal was an appropriate indicator of the renal handling of electrolytes, and when viewed in conjunction with urinalysis and other serum parameters, a valuable aid to evaluating renal function. 相似文献
8.
K.F. Weitze D. Rath T. Willmen D. Waberski J. Lotz 《Reproduction in domestic animals》1990,25(2):61-67
Contents: The relationship between seminal plasma constitutents in the boar ejaculate and ovulation time was investigated in German landrace gilts in a total of 182 heat periods. The animals were inseminated in the first two trials (I = 34 gilts; II = 60 gilts) once at spontaneous heat with seminal plasma free liquid semen after a pretreatment with either 60 ml seminal plasma or dilution medium. In a third experiment (III) 22 gilts were treated in 4 subsequent heat intervals with 120 ml seminal plasma, oestrogen solution or physiological saline at the beginning of standing heat without any application of spermatozoa to investigate the possibility of induction of ovulation. In the inseminated gilts embryos were recovered surgically 3 to 5 days after AI. Fertilization rate and embryo quality were recorded. The time of ovum activation was calculated in a retrospective manner using the corresponding age values of Hunter (1974) for embryo development. Considering a six hour lapse after ovulation for complete activation of all eggs, the probable ovulation time was determined and used for calculation of the interval between insemination and ovulation. In two experimental groups ovulation was determined by trans cutaneous sonography of the ovaries in the standing gilt. This method revealed a seminal plasma dependent advancement of ovulation time ranging between 5 and 14.4 hours. A seminal plasma dependent prostaglandin release in the endometrium is believed to be the main factor in stimulation of the ovulation process . 相似文献
9.
Effects of some commercial preparations of polychlorinated biphenyls in growing piglets. 总被引：1，自引：1，他引：0 下载免费PDF全文
下载免费PDF全文 N S Platonow E B Meads R M Liptrap F Lotz 《Canadian journal of veterinary research》1976,40(4):421-428
Sixty-four piglets were given ad libitum commercial rations containing 250 ppm of polychlorinated biphenyls as Aroclor 1232, Aroclor 1242 and Aroclor 1254 for periods up to 12 weeks. The toxic effects of the polychlorinated biphenyls upon plasma testosterone levels, the blood coagulation system, the gross- and micropathological changes as well as the extent and differences in their distribution and accumulation were studied. Principals given Aroclor 1232, Aroclor 1242 and Aroclor 1254 for the 12 week period gained 30, 10 and 50% more in body weight respectively than did controls. In the context of the present experiment, Aroclors (especially Aroclor 1254) at 250 ppm level in the ration, appeared to act as growth promoting substances. The mode and site of action of this effect is not known. The gross and micropathological examinations of controls and principals gave no evidence of anomalies. Similarly, the data on various parameters of blood coagulation did not reveal any disturbances. However, testosterone levels in plasma were elevated in male piglets given Aroclors. Analyses of polychlorinated biphenyls showed that the highest concentrations were present in adipose tissues of all treated animals. A cumulative tendency was also evident. The levels were relatively high in brain, in some instances higher than in liver of the same group. Levels in hepatic and muscular tissue were, in many instances, of the same magnitude. 相似文献
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