The intermesenteric plexus in the pigeon (Columba livia GM)     

Kuder T  Nowak E  Szczurkowski A 《Anatomia, histologia, embryologia》2001,30(2):85-88

Using the thiocholine method and histological techniques the intermesenteric plexus of the pigeon was studied. The intermesenteric plexus of this species is a plexo-ganglionic structure with several (five to seven) ganglia and nerve fibres. The ganglia have an oval-, spindle- or star-like shape. Single nerve cells along the nerve fibres were observed. The intermesenteric plexus of the pigeon is situated on the ventrolateral surface of the aorta, between the cranial mesenteric artery and caudal mesenteric artery. The connections between the intermesenteric and other vegetative plexuses (coeliac plexus, mesenteric inferior plexus) and the pelvic nerve were observed.  相似文献   

合肥城市森林减少大气污染的效果   总被引：19，自引：6，他引：13  

吴泽民  JoeR.McBride  David J.Nowak  杨军  Sheauchi Cheng 《中国城市林业》2003,1(1):39-43

树木主要通过气孔吸收气态污染物,同时通过滞留空气中的微粒而减轻污染,树木较高的覆盖率可能会减少挥发性有机物的释放量,定量研究表明,合肥市1998年吸收空气污染物约为151.5t,树木7月份(着叶季节)吸收污染量高达20t,具有相对较低臭氧生成潜力的植物有香樟属、女贞属、紫薇属、罗汉松属和李属。合肥城市森林总体的臭氧指标得分值为92.4。    相似文献   

Fairness versus reason in the ultimatum game     

Nowak MA  Page KM  Sigmund K 《Science (New York, N.Y.)》2000,289(5485):1773-1775

In the Ultimatum Game, two players are offered a chance to win a certain sum of money. All they must do is divide it. The proposer suggests how to split the sum. The responder can accept or reject the deal. If the deal is rejected, neither player gets anything. The rational solution, suggested by game theory, is for the proposer to offer the smallest possible share and for the responder to accept it. If humans play the game, however, the most frequent outcome is a fair share. In this paper, we develop an evolutionary approach to the Ultimatum Game. We show that fairness will evolve if the proposer can obtain some information on what deals the responder has accepted in the past. Hence, the evolution of fairness, similarly to the evolution of cooperation, is linked to reputation.  相似文献   

Biodiversity of endophytic bacteria which colonize red clover nodules, roots, stems and foliage and their influence on host growth   总被引：6，自引：0，他引：6  

A. V. Sturz  B. R. Christie  B. G. Matheson  J. Nowak 《Biology and Fertility of Soils》1997,25(1):13-19

The aim of this study was to identifiy the endophytic bacteria recovered from the foliage, tap roots and nodules of red clover plants (Trifolium pratense L.); and to assess the effects of the nodule bacteria, alone and in combination with Rhizobium spp., on the growth and development of red clover seedlings. Thirty-one bacteria species from 14 different genera were recovered from within the foliage, roots and nodules of red clover plants cv. AC Charlie. Genera diversity and species number were greatest in foliage tissues. Pantoea agglomerans (59.6%) was the most frequent species recovered in foliage tissues, Agrobacterium rhizogenes A in the tap root (49.2%) and Rhizobium leguminosarum BV phaseoli and R. loti B in the nodules (27.2% each). Recovery of Rhizobium species was not restricted to the nodules, and species of this genus were systemic throughout the plant. Clover root nodules were host to 12 bacteria species other than rhizobia, of which 8 were specific to this tissue. Using non-selective media, R. leguminosarum BV trifolii constituted only 8.8% of all the root nodule bacteria recovered. In root bacterization experiments, species of nodule bacteria promoted growth of red clover more often when applied in combination with R. leguminosarum BV trifolii than when applied singly. However, Bacillus megaterium, Bordetella avium and Curtobacterium luteum consistently promoted growth either individually or in combination with R. leguminosarum BV trifolii. Nodulation was promoted when R. leguminosarum BV trifolii was coinoculated with Bacillus insolitus, B. brevis or A. rhizogenes A. Single isolate applications of Rhizobium species to roots always led to the depression of clover growth, but mixtures of R. leguminosarum BV trifolii and R. leguminosarum BV phaseoli resulted in growth promotion. The latter is considered further evidence of the beneficial allelopathic side effect of strain competition for the same ecological niche. Received: 27 June 1996  相似文献   

Regenerative trait and cold hardiness in highly productive cultivars of alfalfa and red clover     

Jerzy Nowak  Sherry L. Matheson  Nancy L. McLean  Peter Havard 《Euphytica》1992,59(2-3):189-196

Summary In earlier work on improvement of persistance in forage legumes, we selected genotypes from highly productive cultivars of alfalfa, Algonquin and Apica (Euphytica 45: 105–112, 1990) and cv. Florex red clover (Plant Cell Reports 8: 395–398, 1989) capable of in vitro regeneration from callus and cell culture. The alfalfa germplasm and its F₁ progeny as well as an F₂ red clover population were tested for cold stress tolerance. Plantlets were hardened in culture tubes at 2 or 5°C, 8h photoperiod, for at least four weeks and then subjected to freezing temperatures, –16 or –10°C for alfalfa and red clover, respectively. Survival of regenerative genotypes was significantly higher than of the non-regenerative ones in both species. A strong oositive correlation (r=0.78) between the regenerative trait and plant survival was found in alfalfa. The experiments indicate that in vitro selection for regenerative trait may improve cold stress tolerance of alfalfa and red clover.  相似文献   

Survivability and developmental competences of domestic cat (Felis catus) oocytes after Cryotech method vitrification     

Agnieszka Nowak  Joanna Kochan  Ewa Świętek  Barbara Kij  Sylwia Prochowska  Wojciech Witarski  Monika Bugno-Poniewierska  Wojciech Niżański 《Reproduction in domestic animals》2020,55(8):992-997

The aim of this study was to evaluate the applicability of the Cryotech technique for the vitrification of domestic cat (Felis catus) oocytes, as a model for other feline species threatened with extinction. This technique, in which oocytes are stored in a minimal volume of medium, is already widely used in human assisted reproductive technology. In the first part of this study, a viability test (EtBr/FDA) was used to evaluate the toxicity of the vitrification media (solutions). After IVM, oocytes were placed in vitrification and warming solutions according to the manufacturer's procedure, with or without exposure to liquid nitrogen. The solutions and the vitrification procedure each caused a reduction in oocyte viability, with survival rates of 71.4% in oocytes exposed to the Cryotech media (without cooling in liquid nitrogen), and 62% in oocytes that were vitrified. In the second part of the experiment, parthenogenetic activation was used to evaluate the developmental potential of oocytes previously vitrified using the Cryotech method. After warming, the oocytes were activated using a combination of 0.7 µM ionomycin in TCM 199 medium (5 min) followed by 2 mM 6-DMAP in TCM 199 supplemented with 10% FBS (3 hr), then cultured and evaluated every 24 hr for parthenogenetic cleavage. In the experimental group, 23/50 (46%) cleaved embryos were obtained. Domestic cat oocytes, vitrified by the Cryotech method, are characterized by high survival rates. However, it is necessary to improve the technique to increase the developmental competence of embryos obtained from vitrified oocytes.  相似文献   

Sequential pathology after initial freshwater bath treatment for amoebic gill disease in cultured Atlantic salmon, Salmo salar L     

Adams MB  Nowak BF 《Journal of fish diseases》2004,27(3):163-173

Freshwater bathing is essential for control of amoebic gill disease (AGD) during the marine phase of the Tasmanian Atlantic salmon production cycle, a practice that is costly, production limiting and increasing in frequency. Although the pathogenesis of gill infection with Neoparamoeba sp. in naïve Atlantic salmon, Salmo salar, is now understood, the progression of re‐infection (post‐treatment) required elucidation. Here, we describe the weekly histopathological progression of AGD from first to second freshwater bath. Halocline cessation and increased water temperature appeared to drive the rapid onset of initial infection prior to bathing. Freshwater bathing cleared lesions of attached trophozoites and associated cellular debris. Subsequent gill re‐infection with Neoparamoeba sp. was evident at 2 weeks post‐bath and had significantly increased (P < 0.001), in severity by 4 weeks post‐bath. No significant difference in gross pathology was observed until 4 weeks post‐bath (P < 0.05). The re‐infective progression of AGD was characterized by localized host tissue responses juxtaposed to adhered trophozoites (epithelial oedema, hypertrophy and hyperplasia), non‐specific inflammatory cell infiltration (macrophages, neutrophils and eosinophilic granule cells) and finally advanced hyperplasia with epithelial fortification. During the post‐bath period, non‐AGD lesions including haemorrhage, necrosis and regenerative hyperplasia were occasionally observed, although no evidence of secondary colonization of these lesions by Neoparamoeba sp. was noted. We conclude that pathogenesis during the inter‐bath period was identical to initial infection although the source of re‐infection remains to be established.  相似文献   

Cardiac morphology in relation to amoebic gill disease history in Atlantic salmon, Salmo salar L.     

M D Powell  B F Nowak  & M B Adams 《Journal of fish diseases》2002,25(4):209-215

Fish from cages with histories of heavy and light amoebic gill disease (AGD) outbreaks were harvested and the morphology, histology and activities of lactate dehydrogenase determined. Although fish with a history of heavy AGD were smaller, their heart somatic indices were similar to those of fish with a history of light AGD. However, morphometrically the ratios of ventricle axis length and width and axis length and height were significantly higher, and there was an overall thickening of the muscularis compactum in the ventricle of fish with heavy AGD history. There was no difference in the lactate dehydrogenase activity of the ventricle muscle in the two fish groups. These results suggest that the change in ventricle shape associated with AGD was a possible compensation for an increased afterload where the lengthening of the ventricle was compensated for by an increase in muscle thickness, but without any overall ventricular hypertrophy or gain in ventricular mass. This suggests that AGD may be associated with cardiovascular compromise in affected fish.  相似文献   

The effect of environmental factors on the distribution of Neoparamoeba pemaquidensis in Tasmania     

Douglas-Helders M  Nowak B  Butler R 《Journal of fish diseases》2005,28(10):583-592

Aquaculture in Tasmania is mostly carried out in estuaries. These estuarine habitats show a great variety and form unique environments in which Neoparamoeba pemaquidensis, the amoebic gill disease (AGD)-causing protozoan, may or may not survive. Tasmania is divided into two zones, one where AGD is present and one where AGD is absent, but any ecological data to rationalize this distribution is lacking. In in vitro trials N. pemaquidensis strains were exposed to different concentrations of ammonium sulphate, copper sulphate, copper sulphate and tannin, and different Neoparamoeba densities, salinities and temperatures. A trial using field water samples investigated the survival of N. pemaquidensis in waters sourced from AGD-free and AGD-positive zones, and water analysis was performed to determine any differences. Significantly decreased protozoan survival was found with exposure to increasing copper sulphate concentrations from 10 to 100,000 microM (P < 0.001), salinity of 15 per thousand (P < 0.001), low Neoparamoeba densities of 625 and 1,250 cells mL(-1) (P = 0.0005), and water sourced from Macquarie Harbour (P < 0.001). The water chemistry of this AGD-free zone showed significantly lower dissolved calcium and magnesium concentrations which may contribute to this area being AGD-free. Understanding of the ecology of N. pemaquidensis will enable better control and prevention strategies for Tasmanian salmon growers.  相似文献   

Changes in the innate immune response of Atlantic salmon, Salmo salar L., exposed to experimental infection with Neoparamoeba sp     

Gross KA  Powell MD  Butler R  Morrison RN  Nowak BF 《Journal of fish diseases》2005,28(5):293-299

An experiment was conducted to determine the effect of Neoparamoeba sp. infection on the innate immune responses of Atlantic salmon. Atlantic salmon were experimentally infected with Neoparamoeba sp. and serially sampled 0, 1, 4, 6, 8 and 11 days post-exposure (dpe). Histological analysis of infected fish gill arches identified the presence of characteristic amoebic gill disease lesions as early as 1 dpe with a steady increase in the number of affected gill filaments over time. Immune parameters investigated were anterior kidney phagocyte function (respiratory burst, chemotaxis and phagocytosis) and total plasma protein and lysozyme. In comparison with non-exposed control fish basal respiratory burst responses were suppressed at 8 and 11 dpe, while phorbol myristate acetate-stimulated activity was significantly suppressed at 11 dpe. Variable differences in phagocytic activity and phagocytic rate following infection were identified. There was an increase in the chemotactic response of anterior kidney macrophages isolated from exposed fish relative to control fish at 8 dpe. Total protein and lysozyme levels were not affected by Neoparamoeba sp. exposure.  相似文献