940 resultados para Animals, Fossil
Resumo:
The requirement for growth hormone (GH) secretion by the anterior pituitary gland in beef calves is demonstrated by a complete lack of long bone-growth and muscle accretion after hypophysectomy (surgical removal of the pituitary gland). When the connecting link (hypophyseal stalk) to the basal region (hypothalamus) of the brain is surgically severed, long bone growth and body weight gain are greatly limited compared with sham-operated controls. This limited growth results from obliteration of episodic GH secretion and reduced basal blood concentration of the hormone compared with sham-operated controls. Thus, the hypophyseal stalk-transected (HST) calf provides an appropriate model to determine mechanisms by which hypothalamic neuropeptides from the brain regulate GH secretion, and thereby growth in the young calf. Neuropeptides have been isolated and characterized in bovine hypothalamus that stimulate GH secretion (GH-releasing hormone [GHRH]) or factor [GHRF] and inhibit GH secretion (GH release-inhibiting hormone [GHRIH] or somatostatin [SRIH]). A dose of .067 micrograms of GHRF per kilogram of body weight injected intravenously in HST calves abruptly increased plasma GH concentration to 55 nanograms per milliliter from the control period mean of 5 nanograms per milliliter. HST calves then were infused intravenously with .033 and .067 microgram somatostatin per kilogram of body weight, during which a pulse injection of .067 microgram of GHRF was administered. GH increase was limited to 9 and 5 micrograms per kilogram body weight during the .033- and .067 microgram SRIH infusions after GHRF; no GH rebound was observed after the SRIH was discontinued. GHRF from humans contains 40 to 44 amino acids. Rat hypothalamic GHRF analogs containing 29 to 32 amino acids elicited dose-dependent GH peak release in these HST calves. In 1977, Bowers and Monomy isolated novel GH releasing peptides consisting of only six amino acids; they caused GH release by isolated pituitary cells in culture and acute GH release when administered intravenously. We recently have utilized a novel nonpeptidyl GH secretagogue of low molecular weight in the pig to determine its mechanisms of action within the central nervous system.
Resumo:
Many Member States of the European Union (EU) currently monitor antimicrobial resistance in zoonotic agents, including Salmonella and Campylobacter. According to Directive 2003/99/EC, Member States shall ensure that the monitoring provides comparable data on the occurrence of antimicrobial resistance. The European Commission asked the European Food Safety Authority to prepare detailed specifications for harmonised schemes for monitoring antimicrobial resistance. The objective of these specifications is to lay down provisions for a monitoring and reporting scheme for Salmonella in fowl (Gallus gallus), turkeys and pigs, and for Campylobacter jejuni and Campylobacter coli in broiler chickens. The current specifications are considered to be a first step towards a gradual implementation of comprehensive antimicrobial resistance monitoring at the EU level. These specifications propose to test a common set of antimicrobial agents against available cut-off values and a specified concentration range to determine the susceptibility of Salmonella and Campylobacter. Using isolates collected through programmes in which the sampling frame covers all epidemiological units of the national production, the target number of Salmonella isolates to be included in the antimicrobial resistance monitoring per Member State per year is 170 for each study population (i.e., laying hens, broilers, turkeys and slaughter pigs). The target number of Campylobacter isolates to be included in the antimicrobial resistance monitoring per Member State per year is 170 for each study population (i.e., broilers). The results of the antimicrobial resistance monitoring are assessed and reported in the yearly national report on trends and sources of zoonoses, zoonotic agents and antimicrobial resistance.
Resumo:
The blaESBL and blaAmpC genes in Enterobacteriaceae are spread by plasmid-mediated integrons, insertion sequences, and transposons, some of which are homologous in bacteria from food animals, foods, and humans. These genes have been frequently identified in Escherichia coli and Salmonella from food animals, the most common being blaCTX-M-1, blaCTX-M-14, and blaCMY-2. Identification of risk factors for their occurrence in food animals is complex. In addition to generic antimicrobial use, cephalosporin usage is an important risk factor for selection and spread of these genes. Extensive international trade of animals is a further risk factor. There are no data on the effectiveness of individual control options in reducing public health risks. A highly effective option would be to stop or restrict cephalosporin usage in food animals. Decreasing total antimicrobial use is also of high priority. Implementation of measures to limit strain dissemination (increasing farm biosecurity, controls in animal trade, and other general postharvest controls) are also important.
Resumo:
Fossil pollen data from stratigraphic cores are irregularly spaced in time due to non-linear age-depth relations. Moreover, their marginal distributions may vary over time. We address these features in a nonparametric regression model with errors that are monotone transformations of a latent continuous-time Gaussian process Z(T). Although Z(T) is unobserved, due to monotonicity, under suitable regularity conditions, it can be recovered facilitating further computations such as estimation of the long-memory parameter and the Hermite coefficients. The estimation of Z(T) itself involves estimation of the marginal distribution function of the regression errors. These issues are considered in proposing a plug-in algorithm for optimal bandwidth selection and construction of confidence bands for the trend function. Some high-resolution time series of pollen records from Lago di Origlio in Switzerland, which go back ca. 20,000 years are used to illustrate the methods.
Resumo:
Altitudinal gradients offer valuable study systems to investigate how adap- tive genetic diversity is distributed within and between natural populations and which factors promote or prevent adaptive differentiation. The environ- mental clines along altitudinal gradients tend to be steep relative to the dispersal distance of many organisms, providing an opportunity to study the joint effects of divergent natural selection and gene flow. Temperature is one variable showing consistent altitudinal changes, and altitudinal gradi- ents can therefore provide spatial surrogates for some of the changes antici- pated under climate change. Here, we investigate the extent and patterns of adaptive divergence in animal populations along altitudinal gradients by sur- veying the literature for (i) studies on phenotypic variation assessed under common garden or reciprocal transplant designs and (ii) studies looking for signatures of divergent selection at the molecular level. Phenotypic data show that significant between-population differences are common and taxo- nomically widespread, involving traits such as mass, wing size, tolerance to thermal extremes and melanization. Several lines of evidence suggest that some of the observed differences are adaptively relevant, but rigorous tests of local adaptation or the link between specific phenotypes and fitness are sorely lacking. Evidence for a role of altitudinal adaptation also exists for a number of candidate genes, most prominently haemoglobin, and for anony- mous molecular markers. Novel genomic approaches may provide valuable tools for studying adaptive diversity, also in species that are not amenable to experimentation.
Resumo:
Alternative fuels are increasingly combusted in diesel- and gasoline engines and the contribution of such exhausts to the overall air pollution is on the rise. Recent findings on the possible adverse effects of biodiesel exhaust are contradictive, at least partly resulting from the various fuel qualities, engine types and different operation conditions that were tested. However, most of the studies are biased by undesired interactions between the exhaust samples and biological culture media. We here report how complete, freshly produced exhausts from fossil diesel (B0), from a blend of 20% rapeseed-methyl ester (RME) and 80% fossil diesel (B20) and from pure rapeseed methyl ester (B100) affect a complex 3D cellular model of the human airway epithelium in vitro by exposing the cells at the air–liquid interface. The induction of pro-apoptotic and necrotic cell death, cellular morphology, oxidative stress, and pro-inflammatory responses were assessed. Compared to B0 exhaust, B20 exhaust decreased oxidative stress and pro-inflammatory responses, whereas B100 exhaust, depending on exposure duration, decreased oxidative stress but increased pro-inflammatory responses. The effects are only very weak and given the compared to fossil diesel higher ecological sustainability of biodiesel, it appears that – at least RME – can be considered a valuable alternative to pure fossil diesel.
Resumo:
Radiocarbon offers a unique possibility for unambiguous source apportionment of carbonaceous particles due to a direct distinction of non-fossil and fossil carbon. In this work, particulate matter of different size fractions was collected at 4 sites in Switzerland to examine whether fine and coarse carbonaceous particles exhibit different fossil and contemporary sources. Elemental carbon (EC) and organic carbon (OC) as well as water-soluble OC (WSOC) and water-insoluble OC (WINSOC) were separated and determined for subsequent 14C measurement. In general, both fossil and non-fossil fractions in OC and EC were found more abundant in the fine than in the coarse mode. However, a substantial fraction (~20 ± 5%) of fossil EC was found in coarse particles, which could be attributed to traffic-induced non-exhaust emissions. The contribution of biomass burning to coarse-mode EC in winter was relatively high, which is likely associated to the coating of EC with organic and/or inorganic substances emitted from intensive wood burning. Further, fossil OC (i.e. from vehicle emissions) was found to be smaller than non-fossil OC due to the presence of primary biogenic OC and/or growing in size of wood-burning OC particles during aging processes. 14C content in WSOC indicated that the second organic carbon rather stems from non-fossil precursors for all samples. Interestingly, both fossil and non-fossil WINSOC concentrations were found to be higher in fine particles than in coarse particles in winter, which is likely due to primary wood burning emissions and/or secondary formation of WINSOC.
Resumo:
Recently, the French National Institute for Agricultural Research appointed an expert committee to review the issue of pain in food-producing farm animals. To minimise pain, the authors developed a '3S' approach accounting for 'Suppress, Substitute and Soothe' by analogy with the '3Rs' approach of 'Reduction, Refinement and Replacement' applied in the context of animal experimentation. Thus, when addressing the matter of pain, the following steps and solutions could be assessed, in the light of their feasibility (technical constraints, logistics and regulations), acceptability (societal and financial aspects) and availability. The first solution is to suppress any source of pain that brings no obvious advantage to the animals or the producers, as well as sources of pain for which potential benefits are largely exceeded by the negative effects. For instance, tail docking of cattle has recently been eliminated. Genetic selection on the basis of resistance criteria (as e.g. for lameness in cattle and poultry) or reduction of undesirable traits (e.g. boar taint in pigs) may also reduce painful conditions or procedures. The second solution is to substitute a technique causing pain by another less-painful method. For example, if dehorning cattle is unavoidable, it is preferable to perform it at a very young age, cauterising the horn bud. Animal management and constraint systems should be designed to reduce the risk for injury and bruising. Lastly, in situations where pain is known to be present, because of animal management procedures such as dehorning or castration, or because of pathology, for example lameness, systemic or local pharmacological treatments should be used to soothe pain. These treatments should take into account the duration of pain, which, in the case of some management procedures or diseases, may persist for longer periods. The administration of pain medication may require the intervention of veterinarians, but exemptions exist where breeders are allowed to use local anaesthesia (e.g. castration and dehorning in Switzerland). Extension of such exemptions, national or European legislation on pain management, or the introduction of animal welfare codes by retailers into their meat products may help further developments. In addition, veterinarians and farmers should be given the necessary tools and information to take into account animal pain in their management decisions.
Resumo:
When comparing the transporters of three completely sequenced eukaryotic genomes - Saccharomyces cerevisiae, Arabidopsis thaliana and Homo sapiens - transporter types can be distinguished according to phylogeny, substrate spectrum, transport mechanism and cell specificity. The known amino acid transporters belong to five different superfamilies. Two preferentially Na+-coupled transporter superfamilies are not represented in them yeast and Arabidopsis genomes, whereas the other three groups, which often function as H+-coupled systems, have members in all investigated genomes. Additional superfamilies exist for organellar transport, including mitochondrial and plastidic carriers. When used in combination with phylogenetic analyses, functional comparison might aid our prediction of physiological functions for related but uncharacterized open reading frames.
Climate refugia: joint inference from fossil records, species distribution models and phylogeography
Resumo:
Climate refugia, locations where taxa survive periods of regionally adverse climate, are thought to be critical for maintaining biodiversity through the glacial–interglacial climate changes of the Quaternary. A critical research need is to better integrate and reconcile the three major lines of evidence used to infer the existence of past refugia – fossil records, species distribution models and phylogeographic surveys – in order to characterize the complex spatiotemporal trajectories of species and populations in and out of refugia. Here we review the complementary strengths, limitations and new advances for these three approaches. We provide case studies to illustrate their combined application, and point the way towards new opportunities for synthesizing these disparate lines of evidence. Case studies with European beech, Qinghai spruce and Douglas-fir illustrate how the combination of these three approaches successfully resolves complex species histories not attainable from any one approach. Promising new statistical techniques can capitalize on the strengths of each method and provide a robust quantitative reconstruction of species history. Studying past refugia can help identify contemporary refugia and clarify their conservation significance, in particular by elucidating the fine-scale processes and the particular geographic locations that buffer species against rapidly changing climate.
Resumo:
Avulsion of nerve roots of the brachial plexus can be diagnosed clinically, neurologically, radiographically and by electromyography. But like the myelography these techniques are inprecise for determination of the severity (partial or complete disruption) and the localization of the lesion. In human medicine the combination of computerized tomography with myelography shows high accuracy. Veterinary reports of experience in this field are not yet known. The aim of the present study was to demonstrate nerve root avulsions using myelography and computerized tomography. Three dogs and one cat with traumatic lesions of the brachial plexus were examined. The lesion could be seen in all patients. Thus CT-myelography results in an improved prognostic assessment of brachial plexus paralysis. Moreover, this technique could become one of the most important diagnostic methods for brachial plexus lesions involving nerve root reinsertion--neurotizations in veterinary medicine.
Resumo:
The acquisition of accurate information on the size of traits in animals is fundamental for the study of animal ecology and evolution and their management. We demonstrate how morphological traits of free-ranging animals can reliably be estimated on very large observation distances of several hundred meters by the use of ordinary digital photographic equipment and simple photogrammetric software. In our study, we estimated the length of horn annuli in free-ranging male Alpine ibex (Capra ibex) by taking already measured horn annuli of conspecifics on the same photographs as scaling units. Comparisons with hand-measured horn annuli lengths and repeatability analyses revealed a high accuracy of the photogrammetric estimates. If length estimations of specific horn annuli are based on multiple photographs measurement errors of <5.5 mm can be expected. In the current study the application of the described photogrammetric procedure increased the sample size of animals with known horn annuli length by an additional 104%. The presented photogrammetric procedure is of broad applicability and represents an easy, robust and cost-efficient method for the measuring of individuals in populations where animals are hard to capture or to approach.