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1.
The acanthocephalan parasite Pomphorhynchus laevis (Müller, 1776) uses freshwater amphipods as its intermediate host. In order to complete the life cycle, the infected amphipod must be consumed by a fish, where the acanthocephalan will mature and reproduce. Parasite transmission, and therefore fitness, could be enhanced if infected amphipods fail to detect or avoid predatory fish. We compared the activity levels of infected and non-infected amphipods, Echinogammarus stammeri (Karaman, 1931), in both the presence and absence of odours from its natural, definitive host, the fish Leuciscus cephalus (L.). Throughout the experiment, infected amphipods were more active than were non-infected individuals. The non-infected amphipods reduced their activity after the addition of fish odours, but the infected amphipods failed to show a significant decrease. The failure of infected amphipods to reduce activity levels in the presence of fish odour may reflect a parasite strategy to increase its chances of transmission by making its amphipod host more vulnerable to predation by fish. 相似文献
2.
Glucose transport and milk secretion during manipulated plasma insulin and glucose concentrations and during LPS‐induced mastitis in dairy cows 
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下载免费PDF全文 J. J. Gross H. A. van Dorland O. Wellnitz R. M. Bruckmaier 《Journal of animal physiology and animal nutrition》2015,99(4):747-756
In dairy cows, glucose is essential as energy source and substrate for milk constituents. The objective of this study was to investigate effects of long‐term manipulated glucose and insulin concentrations in combination with a LPS‐induced mastitis on mRNA abundance of glucose transporters and factors involved in milk composition. Focusing on direct effects of insulin and glucose without influence of periparturient endocrine adaptations, 18 dairy cows (28 ± 6 weeks of lactation) were randomly assigned to one of three infusion treatments for 56 h (six animals each). Treatments included a hyperinsulinemic hypoglycaemic clamp (HypoG), a hyperinsulinemic euglycaemic clamp (EuG) and a control group (NaCl). After 48 h of infusions, an intramammary challenge with LPS from E. coli was performed and infusions continued for additional 8 h. Mammary gland biopsies were taken before, at 48 (before LPS challenge) and at 56 h (after LPS challenge) of infusion, and mRNA abundance of genes involved in mammary gland metabolism was measured by RT‐qPCR. During the 48 h of infusions, mRNA abundance of glucose transporters GLUT1, 3, 4, 8, 12, SGLT1, 2) was not affected in HypoG, while they were downregulated in EuG. The mRNA abundance of alpha‐lactalbumin, insulin‐induced gene 1, κ‐casein and acetyl‐CoA carboxylase was downregulated in HypoG, but not affected in EuG. Contrary during the intramammary LPS challenge, most of the glucose transporters were downregulated in NaCl and HypoG, but not in EuG. The mRNA abundance of glucose transporters in the mammary gland seems not to be affected by a shortage of glucose, while enzymes and milk constituents directly depending on glucose as a substrate are immediately downregulated. During LPS‐induced mastitis in combination with hypoglycaemia, mammary gland metabolism was more aligned to save glucose for the immune system compared to a situation without limited glucose availability during EuG. 相似文献
3.
A. Stark O. Wellnitz C. Dechow R. Bruckmaier C. Baumrucker 《Journal of animal physiology and animal nutrition》2015,99(2):356-366
Colostrum immunoglobulin G (IgG) is of major importance for the newborn calf because epitheliochorial placentae do not provide transport in utero. The formation of colostrum occurs in the later stages of pregnancy. Our objectives were to induce lactation in non‐pregnant dairy cows and (i) to determine the changes of IgG in serum and mammary secretions during the induction process and (ii) to establish α‐lactalbumin (αLA) and prolactin (Prl) alterations to monitor the changing mammary epithelial tight junction status and development pattern. Estradiol‐17β (E2) and progesterone (P4) injections in a 1–7 days series were combined with a 3‐day injection series (day 21–23) of dexamethasone (DEX). Blood and both front quarter secretion samples were collected daily. Milking started 24 days after the start of the experiment. Results show that the mammary secretory IgG1 was increased at >7 days after the start of steroid injections and depicted a bimodal pattern reaching a high of 16 mg/ml at 21 day compared with 3.2 mg/ml in the serum. There was a small increase in secretory IgG2 that did not correlate with tight junction status, but never reached the serum concentration. The injections of DEX resulted in constriction of tight junctions. Secretory αLA was immediately increased with steroid injections, dropped precipitously after 7 days and then began a steady increase until the start of milking. Changes in serum αLA are related to mammary tight junctions while serum Prl gradually increased from 30 to >60 ng/ml after the steroid injections stopped. These results provide insights into the mechanisms and timing of colostrogenesis during an induced lactation protocol. 相似文献
4.
Rupture of the suspensory ligament at the insertions on the proximal sesamoid bones, and of the superficial flexor tendon of the left fore limb, occurred in an adult Angus bull as a result of fighting. There was severe hyperextension of the metacarpophalangeal (MCP) joint with the dewclaws almost touching the ground. Radiographs revealed severe hyper-extension of the MCP joint with the sesamoid bones aligned directly distal to the metacarpus. Initially, a full length fiberglass cast was applied with the limb partially flexed within the cast and the heels elevated. The cast was replaced twice. The cast was removed after 136 days and the bull was bearing full weight on the limb. Prolonged immobilisation of the limb produced new bone in the area (a normal response in cattle) to cause ankylosis of the traumatized MCP joint and partial ankylosis of the carpus. The bull was being used for pasture breeding one year after the injury. 相似文献
5.
Mechanical comparison of materials used for extra-capsular stabilisation of the stifle joint in dogs
Objective The mechanical properties of three materials (No. 2 polypropylene, No. 5 polybutilate-coated multifilament polyester and 18, 27 and 36 kg test monofilament nylon leader material) commonly used for extra-capsular stabilisation of the stifle in dogs with cranial cruciate ligament insufficiency were determined. The ability of No. 5 polybutilate-coated multifilament polyester and 36 kg test monofilament nylon leader material, when placed as extra-capsular sutures, to mitigate cranial drawer was evaluated in hindlimbs of cadavers. Design An in vitro mechanical study. Animals Seven pairs of hindlimbs harvested from adult greyhound dogs recently euthanased for other reasons. Procedure Samples of each material, including samples of 27 kg test leader material that had been sterilised by one of three methods (ethylene oxide, one or five cycles in an autoclave), were loaded to determine tensile and stress relaxation properties. The effect of cyclic loading on a No. 5 polybutilate-coated multifilament polyester and 36 kg test leader material was also determined. Using the harvested hindlimbs, cranial drawer was measured before and after transection of the cranial cruciate ligament and on the first and twelfth cycle following extra-capsular stabilisation with either No. 5 polybu-tilate-coated multifilament suture or 36 kg test leader material. Results Leader material was found to have the most suitable mechanical characteristics for use as extracapsular stabilisation of the cranial cruciate ligament deficient stifle. Of the sterilisation methods, ethylene oxide was found to have the least detrimental effects on the handling and material characteristics of the leader material. Stifles stabilised with 36 kg test leader material had significantly less drawer than those stabilised with No. 5 polybutilate-coated multifilament polyester suture. Clinical implications Monofilament nylon leader material would appear to have suitable mechanical properties for extra-capsular stabilisation of the cranial cruciate ligament deficient stifle. If possible the material should be sterilised using ethylene oxide. 相似文献
6.
Sunshine JM A'Hearn MF Groussin O Li JY Belton MJ Delamere WA Kissel J Klaasen KP McFadden LA Meech KJ Melosh HJ Schultz PH Thomas PC Veverka J Yeomans DK Busko IC Desnoyer M Farnham TL Feaga LM Hampton DL Lindler DJ Lisse CM Wellnitz DD 《Science (New York, N.Y.)》2006,311(5766):1453-1455
We report the direct detection of solid water ice deposits exposed on the surface of comet 9P/Tempel 1, as observed by the Deep Impact mission. Three anomalously colored areas are shown to include water ice on the basis of their near-infrared spectra, which include diagnostic water ice absorptions at wavelengths of 1.5 and 2.0 micrometers. These absorptions are well modeled as a mixture of nearby non-ice regions and 3 to 6% water ice particles 10 to 50 micrometers in diameter. These particle sizes are larger than those ejected during the impact experiment, which suggests that the surface deposits are loose aggregates. The total area of exposed water ice is substantially less than that required to support the observed ambient outgassing from the comet, which likely has additional source regions below the surface. 相似文献
7.
Streptococcus uberis is the most common environmental mastitis pathogen causing udder inflammations of different severities in dairy cows. The aim of the study was to investigate if the different clinical outcome of mastitis induced by different strains of S. uberis can be reflected in the mammary immune response. Mammary epithelial cells and somatic milk cells were treated with heat inactivated and living S. uberis of strain A and strain B in vitro. Strain A was repeatedly isolated from a chronically infected quarter during 8 months, and persisted in the quarter despite antibiotic treatment. Strain B caused an acute clinical mastitis and was not further isolated after a single antibiotic treatment. Treatment with Strain B induced a more pronounced increase of mRNA-expression of various immune factors (interleukin-8, interleukin-1beta, RANTES, and lactoferrin) in mammary epithelial cells than strain A. In contrast to mammary epithelial cells the response of removed somatic milk cells showed no differences between the stimulation with two S. uberis strains. Tumor necrosis factor-alpha mRNA expression was not differently induced by the two strains. In conclusion, the characteristics of different severities of mastitis that are induced by different S. uberis strains in vivo can also be reflected at the level of the immune response of the mammary gland in vitro. 相似文献
8.
Intra-mammary (IM) bacterial infection in cattle can result in clinical outcomes that range from being acute and life-threatening to those that are chronic and sub-clinical. The typical bacteria involved in IM bacterial infections activate the mammary immune system in different ways which can influence the severity of the outcome. A clear understanding of the mechanisms that activate and regulate this response is central to the development of effective preventative and treatment regimes. This review focuses on the different immune responses of the bovine mammary gland to common mastitis-causing pathogens. There is special emphasis on comparing the responses to Escherichia coli and Staphylococcus aureus infections, as these are typically associated, respectively, with acute/severe and chronic/sub-clinical forms of the disease. 相似文献
9.
PC Sereno AL Beck DB Dutheil B Gado HCE Larsson GH Lyon JD Marcot OWM Rauhut RW Sadleir CA Sidor DD Varricchio GP Wilson JA Wilson 《Science (New York, N.Y.)》1998,282(5392):1298-1302
Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous. 相似文献
10.
DM Magalhães DD Fernandes MBS Mororó CMG Silva GQ Rodrigues JB Bruno MHT Matos CC Campello JR Figueiredo 《Reproduction in domestic animals》2011,46(1):134-140
The aim of the present study was to evaluate the effects of different medium replacement intervals on the viability, antral cavity formation, growth and in vitro maturation (IVM) of oocytes from caprine and ovine pre‐antral follicles. Pre‐antral ovarian follicles (≥150 μm) were isolated from the ovarian cortex of goats and sheep and were individually cultured for 24 days using two different medium replacement intervals [2 days (T1) or 6 days (T2)]. Follicle development was evaluated on the basis of antral cavity formation, increases in follicular diameter and the presence of healthy cumulus oocyte complexes and fully grown oocytes. For caprine species, results showed a higher percentage (p < 0.05) of viable follicles in T1 than T2 from day 6 until the end of the culture. In addition, when comparing both treatments after the same culture duration, the rate of antrum formation was significantly higher in T1 than in T2 from day 12 onwards. Yet, in ovines, when both treatments were compared on day 24 of the culture, there were more viable follicles in T2 than in T1 (p < 0.05). In the caprine species, percentages of fully grown oocytes (≥110 μm) acceptable for IVM after 24 days of culture were significantly higher in normal follicles cultured in T1 (30.0%) than in T2 (6.7%; p < 0.05). On the other hand, in ovines, at the end of the culture, the percentage of oocytes destined for IVM was higher in T2 than in T1 (23.5% vs 2.9%; p < 0.05). In conclusion, under the same conditions, the frequency of medium replacement significantly affected the in vitro development of caprine and ovine pre‐antral follicles. To improve the efficiency of the culture system, the medium must be replaced every 2 and 6 days for goat and sheep pre‐antral follicles, respectively. 相似文献