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The orientation of an animal moving in a plane towards a point-like mark is investigated. The control exerted by the optomotor (tracking) response on the motion of the animal is interpreted as an external force acting on the animal itself, which is modeled as a dipole or as a single point.The optomotor response is assumed as a rather general function of distance and angle. Differential equations governing the motion are derived and analyzed qualitatively and numerically. The role of distance-dependence and of the width of the visual field is investigated in detail and related to some typical kinds of paths in the plane, such as hitting the mark, coming close to the mark within a short distance, circular or undulating motion around the mark.A first version of this paper has been read at the Oberwolfach Conference on Mathematical Biology, June 1978 相似文献
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Plant models for animal pathogenesis 总被引:3,自引:0,他引:3
Several bacteria that are pathogenic to animals also infect plants. Mechanistic studies have proven that some human/animal pathogenic bacteria employ a similar subset of virulence determinants to elicit disease in animals, invertebrates and plants. Therefore, the results of plant infection studies are relevant to animal pathogenesis. This discovery has resulted in the development of convenient, cost-effective, and reliable plant infection models to study the molecular basis of infection by animal pathogens. Plant infection models provide a number of advantages in the study of animal pathogenesis. Using a plant model, mutations in animal pathogenic bacteria can easily be screened for putative virulence factors, a process which if done using existing animal infection models would be time-consuming and tedious. High-throughput screening of plants also provides the potential for unravelling the mechanisms by which plants resist animal pathogenic bacteria, and provides a means to discover novel therapeutic agents such as antibiotics and anti-infective compounds. In this review, we describe the developing technique of using plants as a model system to study Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus pathogenesis, and discuss ways to use this new technology against disease warfare and other types of bioterrorism. 相似文献
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Livestock production is an important source of animal protein worldwide. In the developed world meat consumption will remain steady but demand is forecast to grow enormously in developing countries. The use of genomics will speed genetic improvement and increase levels of production quickly in the developed world but might face problems in the developing world, including scientific, economic and political challenges. Considerable increases in public and private research funding will be required to develop and utilize novel tools and collections of detailed trait information on appropriate animals. The development of policies protecting the environment and managing all genetic resources will also be needed. Advances in livestock genomics have major implications for increasing food output as well as improving human health. 相似文献
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Early scientific studies conducted at the turn of the twentieth century failed to support the inclusion of seaweeds into animal rations at high inclusion rates. At that time, based on proximate analysis and energy availability studies, dried seaweeds or kelp meal largely fell out of favor as a recommended animal feed source. Nevertheless, kelp meal was still regarded by some as having properties which improved animal health and productivity which were not conveniently explained by conventional feed analysis. In the 1970s, research leads to the discovery that chelated micromineral sources were more efficient for the delivery of microelements than conventional inorganic sources. This prompted renewed interest in seaweeds as rich sources of over 60+ microelements. However, it was only in the early 2000s, when detailed analysis of the complex structure of the polysaccharides associated with seaweeds was tied to their prebiotic actions, that a clear explanation for the basis of productivity and health enhancement was attained. Further analysis indicated that other constituents in various brown seaweeds such as phlorotannins and antioxidants also contributed to the observed bioactivities. Of all of the brown seaweeds cited in studies, the one most scientifically documented is Ascophyllum nodosum, and of all of these sources, Tasco®, a sundried, high-quality macroalgal product, produced by Acadian Seaplants has been the most studied. The latest studies of Tasco® suggest prebiotic potencies at least five times that of the reference prebiotic inulin with additional performance-enhancing benefits in animal rations that rival antibiotic inclusions. 相似文献
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A variety of plant species have been genetically modified to accumulate vaccine antigens for human and animal health and the
first vaccine candidates are approaching the market. The regulatory burden for animal vaccines is less than that for human
use and this has attracted the attention of researchers and companies, and investment in plant-made vaccines for animal infectious
disease control is increasing. The dosage cost of vaccines for animal infectious diseases must be kept to a minimum, especially
for non-lethal diseases that diminish animal welfare and growth, so efficient and economic production, storage and delivery
are critical for commercialization. It has become clear that transgenic plants are an economic and efficient alternative to
fermentation for large-scale production of vaccine antigens. The oral delivery of plant-made vaccines is particularly attractive
since the expensive purification step can be avoided further reducing the cost per dose. This review covers the current status
of plant-produced vaccines for the prevention of disease in animals and focuses on barriers to the development of such products
and methods to overcome them. 相似文献
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M L Lenhardt 《Laboratory animal science》1979,29(6):812-813
A hand activated pneumatic whistle produced a stable acoustic burst. The whistle was adjustable and the frequency could be selected over a range of 6-14 kilohertz. The whistle was useful in screening hearing in animals. 相似文献
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Metazoans emerged in a microbial world and play a unique role in the biosphere as the only complex multicellular eukaryotes capable of phagocytosis. While the bodyplan and feeding mode of the last common metazoan ancestor remain unresolved, the earliest multicellular stem‐metazoans likely subsisted on picoplankton (planktonic microbes 0.2–2 μm in diameter) and dissolved organic matter (DOM), similarly to modern sponges. Once multicellular stem‐metazoans emerged, they conceivably modulated both the local availability of picoplankton, which they preferentially removed from the water column for feeding, and detrital particles 2–100 μm in diameter, which they expelled and deposited into the benthos as waste products. By influencing the availability of these heterotrophic food sources, the earliest multicellular stem‐metazoans would have acted as ecosystem engineers, helping create the ecological conditions under which other metazoans, namely detritivores and non‐sponge suspension feeders incapable of subsisting on picoplankton and DOM, could emerge and diversify. This early style of metazoan feeding, specifically the phagocytosis of small eukaryotic prey, could have also encouraged the evolution of larger, even multicellular, eukaryotic forms less prone to metazoan consumption. Therefore, the first multicellular stem‐metazoans, through their feeding, arguably helped bridge the strictly microbial food webs of the Proterozoic Eon (2.5–0.541 billion years ago) to the more macroscopic, metazoan‐sustaining food webs of the Phanerozoic Eon (0.541–0 billion years ago). 相似文献
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转基因动物的研究目前尚处于实验室研究阶段,获得转基因动物难度大,检测转基因比较困难,从染色体和基因水平、转录、翻译、整体表型等不同角度介绍了转基因动物的不同检测手段和方法,并对各水平存在的问题及应用前景作了阐述。 相似文献
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The requirements for veterinary vaccines are different to those of human vaccines. Indeed, while more side effects can be tolerated in animals than in humans; there are stricter requirements in terms of cost, ease of delivery (including to wildlife), and a need to develop vaccines in species for which relatively little is known in terms of molecular immunology. By their nature particulate vaccine delivery systems are well suited to address these challenges. Here, we review particulate vaccine delivery systems, ranging from cm-sized long-distance ballistic devices to nano-bead technology for veterinary species and wildlife. 相似文献
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Emma Lynch Lisa Angeloni Kurt Fristrup Damon Joyce George Wittemyer 《Ecology and evolution》2013,3(7):2030-2037
Audio recordings made from free‐ranging animals can be used to investigate aspects of physiology, behavior, and ecology through acoustic signal processing. On‐animal acoustical monitoring applications allow continuous remote data collection, and can serve to address questions across temporal and spatial scales. We report on the design of an inexpensive collar‐mounted recording device and present data on the activity budget of wild mule deer (Odocoileus hemionus) derived from these devices applied for a 2‐week period. Over 3300 h of acoustical recordings were collected from 10 deer on their winter range in a natural gas extraction field in northwestern Colorado. Analysis of a subset of the data indicated deer spent approximately 33.5% of their time browsing, 20.8% of their time processing food through mastication, and nearly 38.3% of their time digesting through rumination, with marked differences in diel patterning of these activities. Systematic auditory vigilance was a salient activity when masticating, and these data offer options for quantifying wildlife responses to varying listening conditions and predation risk. These results (validated using direct observation) demonstrate that acoustical monitoring is a viable and accurate method for characterizing individual time budgets and behaviors of ungulates, and may provide new insight into the ways external forces affect wildlife behavior. 相似文献
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Surfactant-mediated gene transfer for animal cells 总被引:3,自引:0,他引:3
A commercially available cationic surfactant, dimethyl-dioctadecyl ammonium bromide (DDAB), was used for making lipid vesicles.
DDAB easily dissolved in water at 60 °C and formed lipid vesicles at room temperature. The lipid vesicles showed very low
cytotoxicity compared with other cationic surfactants. After the lipid vesicles were mixed with plasmid DNA solution, the
solution was added to mammalian cells. The addition of a nonionic surfactant (Tween 80) to the cationic lipid vesicles at
the weight ratio of 1:1 enhanced transfection efficiency. Adding more or less than the optimal amounts of DNA and lipid vesicles
resulted in decreased transfection efficiency. With the optimal amounts of DNA (pCMVβ) and lipid vesicles, about 90–95% of
CHO-K1 and BHK-21C13 cells transiently expressed β-galactosidase activity 24 h after transfection. By this procedure, stable
transformants around 105 cells corresponding to 10% efficiency could be obtained by one batch transfection.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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A versatile vector set for animal transgenesis 总被引:18,自引:0,他引:18
Genetic manipulation of a series of diverged arthropods is a highly desirable goal for a better understanding of developmental
and evolutionary processes. A major obstacle so far has been the difficulty in obtaining marker genes that allow easy and
reliable identification of transgenic animals. Here, we present a versatile vector set for germline transformation based on
the promiscuous transposons mariner, Hermes and piggyBac. Into these vectors, we introduced a potentially universal marker system that is comprised of an artificial promoter containing
three Pax-6 homodimer binding sites. This promoter drives strong expression of spectral variants of the enhanced green fluorescent
protein (EGFP) in larval, pupal, and adult photoreceptors. Using special filter sets, the yellow (EYFP) and cyan (ECFP) variant
are fully distinguishable and therefore represent a separable pair of markers. Furthermore, we adapted a simple plasmid-based
transposition assay system to enable quick functional tests of our vectors in different arthropod species before employing
them in more laborious germline transformation experiments. Using this system we demonstrate that our vectors transpose in
both Drosophila melanogaster and Drosophila virilis.
Received: 11 July 2000 / Accepted: 27 July 2000 相似文献
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Grundy MA Gorman N Sinclair PR Chorney MJ Gerhard GS 《Journal of biochemical and biophysical methods》2004,59(2):195-200
Iron has been widely studied in nearly every realm of biology. However, current methodologies, such as genetic mapping or mutation screening, have been difficult to apply due to the lack of robust high-throughput methods for quantifying iron levels from cells or tissues. The measurement of total iron levels in tissues, usually done with atomic absorption spectroscopy, is impractical for large numbers of samples and includes the contribution of heme iron from hemoglobin contained in red blood cells. The measurement of non-heme iron by reaction with a bathophenanthroline reagent, a commonly used assay reported more than 30 years ago, is also not feasible for large-scale analyses because it is cuvette-based. We therefore have modified this method to a microplate format that will facilitate large-scale analysis. The microplate assay is highly sensitive and specific, and is a simple and effective method for the measurement of non-heme iron for animal tissues that will enable the application of high-throughput of genetic methodologies. 相似文献
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Manufacturers of vaccines and other biologicals are under increasing pressure from regulatory agencies to develop production
methods that are completely animal-component-free. In order to comply with this demand, alternative cell culture substrates
to those now on the market, primarily collagen or gelatin, must be found. In this paper, we have tested a number of possible
substitutes including recombinant collagen, a 100-kDa recombinant gelatin fragment and a peptide derived from a cell-binding
region of type I collagen. The small 15-amino acid peptide did not support attachment of human fibroblasts in monolayer culture.
The 100-kDa gelatin fragment supported cell attachment in monolayer culture, but was significantly less active than intact
porcine gelatin. Recombinant type I collagen was as successful in promoting cell attachment as native collagen, and both were
more effective than porcine gelatin. Based on these data, dextran microspheres were treated with the same attachment proteins—porcine
gelatin, native collagen, or recombinant collagen. The same trends were observed as in monolayer culture. Concentrations of
the recombinant collagen (as well as native collagen) supported cell attachment on dextran microspheres at concentrations
as low as 0.01 μg/cm2. Treatment of the dextran with a low level of polyethylenimine, a cationic moiety, further enhanced attachment when used
in conjunction with the low concentration of recombinant collagen. Where there was increased cell attachment, increased proliferation
followed. We are confident, based on these findings, that a fully recombinant substitute could replace gelatin in current
microcarrier preparations without losing the cell growth benefits provided by the native protein. 相似文献
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Although working with human pathogens and zoonotic agents has always carried a certain degree of danger, current events have resulted in an increased focus on the subject, including new regulations. The authors discuss a number of risk assessment and management activities that animal research facilities should use to evaluate strengthen their current programs. 相似文献