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61.
Natural regeneration measurements are the main silvicultural objective in overaged protective forests of the Bavarian Limestone
Alps. While manifold problems with these stands, especially the impact of browsing, are widely recognised, the regeneration
niches of Norway spruce (Picea abies [L.] Karst.) are insufficiently known. The purpose of this study was to determine favourable combinations of site factors
for the development of spruce in small, unfenced canopy gaps, located on Aposerido-Fagetum caricetosum albae forest sites. We recorded the occurrence of spruce saplings (as dependent variable) and of six site factors (as independent
variables) on 480 0.5 m2-subplots. In addition, we estimated the coverage of six acid adapted plant species to determine correlations with the humus
depth. A binary logistic regression analysis was used to predict the probability of the occurrence of a spruce sapling in
dependency of the different site factors. Supported by other studies, we assumed that the supply of solar radiation was adequate
for the sufficient regeneration of spruce within the canopy gaps. Other site factors significantly determined the regeneration
niches of spruce saplings. More spruce saplings were found near hindrances and on rough surfaces than would be expected from
a random occurrence of saplings. These microsite types may have characteristics, especially protection against snow gliding
that promotes spruce establishment. A calculated “hindrance index”, which accounted for the number, and the distance of surrounding
hindrances might be a good specific value to describe the influence of hindrances on steep slopes. The sapling establishment
decreased on thin humus layers. Our assumption for the sites was that thick organic layers might represent a good seedbed
for spruce. Decayed dead wood was scarce, but was exceedingly favoured by spruce saplings. Results obtained suggest that the
natural regeneration establishment of spruce on steep slopes can be successfully influenced by site factors which inhibit
the influence of snow gliding. According to a “positive microsite” concept, we recommend for artificial regeneration measurements
with spruce, microsites close to hindrances (e.g. stumps, downed trees) and Vaccinium myrtillus as a predictor for thick, acid humus layers. 相似文献
62.
Papassotiropoulos A Stephan DA Huentelman MJ Hoerndli FJ Craig DW Pearson JV Huynh KD Brunner F Corneveaux J Osborne D Wollmer MA Aerni A Coluccia D Hänggi J Mondadori CR Buchmann A Reiman EM Caselli RJ Henke K de Quervain DJ 《Science (New York, N.Y.)》2006,314(5798):475-478
Human memory is a polygenic trait. We performed a genome-wide screen to identify memory-related gene variants. A genomic locus encoding the brain protein KIBRA was significantly associated with memory performance in three independent, cognitively normal cohorts from Switzerland and the United States. Gene expression studies showed that KIBRA was expressed in memory-related brain structures. Functional magnetic resonance imaging detected KIBRA allele-dependent differences in hippocampal activations during memory retrieval. Evidence from these experiments suggests a role for KIBRA in human memory. 相似文献
63.
Duncker SC Lorentz A Schroeder B Breves G Bischoff SC 《Veterinary immunology and immunopathology》2006,111(3-4):239-250
Several beneficial effects of probiotics have been described in studies using rodent disease models and in human patients; however, the underlying mechanisms remained mostly unclear. Only a few studies focused on the effects of probiotics on the intestinal mucosal immune system. Here, we studied the effect of the probiotic strain E. coli Nissle 1917 (EcN) administered orally to young pigs at two concentrations (10(9) and 10(11)CFU/d for 21 days) on the gut-associated lymphatic tissue. This probiotic strain was shown recently to reduce recurrence of inflammation in ulcerative colitis patients. We quantified the number and distribution of intestinal immune cells (granulocytes, mast cells, CD4+, CD8+, CD25+, IgA+ lymphocytes) and the mucosal mRNA expression of cytokines (IFN-gamma, TNF-alpha, TGF-beta, IL-10) and antimicrobial peptides (PR-39, NK-lysin, prepro-defensin-beta 1, protegrins). The number and distribution of cells were highly different between small intestinal and colon segments in all groups, but were not influenced by EcN, except high dose EcN fed pigs (10(11) CFU/d) showing an increase in mucosal CD8+ cells in the ascending colon. The mRNA analysis revealed no changes associated with EcN feeding. In conclusion, according to our analyses EcN has only minor effects on the distribution of mucosal immune cells in the gut of healthy individuals. The well-established preventive effects of EcN might therefore be relate to other mechanisms than simple modulation of immune cell distribution. 相似文献
64.
Comparison of new foliar nutrient thresholds derived from van den Burg’s literature compilation with established central European references 总被引:1,自引:1,他引:0
In this paper, we suggest new nutrient threshold values and ratios for the major nutrients (N, P, K, Ca, Mg) for four main trees species Pinus sylvestris, Picea abies, Fagus sylvatica and Quercus (Q. robur and Q. petraea) statistically derived from the data collection of van den Burg’s literature compilation (1985, 1990), and compare them with widely used central European literature. The comparison is focused on the normal range of nutrition of major elements. We could show that the new critical foliar nutrient concentrations and ratios do not have the imponderabilities of the established reference systems, like restricted calibration range or data gaps for species in general or some major nutrients in particular. Ranges from the new critical foliar nutrient concentrations are generally smaller, except for broadleaves foliar Ca and Mg values, where another reference provides the narrowest ranges. The practicability of the different systems has been exemplary tested on a foliage data set of Norway spruce from the Bavarian soil survey. This application illustrates that an evaluation based on the new nutrient thresholds is in the majority of cases more cautious than the other reference systems. Moreover, evaluations based on the new concentrations and ratios are quite consistent. Comparisons with nutrient ratios related to the susceptibility to parasite attacks show that the thresholds are close to a general optimum range, indicating health and intact resistance mechanisms of these tree species. Uncertainties of the new threshold values as well as the need to further evaluate and develop reference systems for nutrient status of forest trees are discussed. 相似文献
65.
Löhr CV Polster U Kuhnert P Karger A Rurangirwa FR Teifke JP 《Veterinary pathology》2012,49(4):592-601
Actinobacillus suis-like organisms (ASLOs) have been isolated from the genital, respiratory, and digestive tracts of healthy adult horses, horses with respiratory disease, and septic foals. Two foals with congenital hypothyroidism-dysmaturity syndrome from separate farms developed ASLO infection. At necropsy, both had contracted carpal flexor tendons, thyroid hyperplasia, and thrombotic and necrotizing mesenteric lymphangitis and lymphadenitis; one foal also had mandibular prognathism. Numerous ASLOs were isolated from tissues from both foals, including intestine. Biochemical testing and mass spectrometric analysis of the two Actinobacillus isolates did not allow unequivocal identification. Comparative genetic analysis was done on these and similar isolates, including phylogeny based on 16S rRNA, rpoB and recN genes, as well as RTX (repeat in toxin) toxin typing of apxIA-apxIVA and aqxA genes. One isolate was identified as Actinobacillus suis sensu stricto, based on the presence of apxIA and apxIIA but not aqxA, whereas the other isolate had aqxA but neither apxIA nor apxIIA, consistent with A equuli ssp haemolyticus. Based on genotypic analysis of the isolates included for comparison, 3 of 3 equine ASLOs and 2 of 5 A equuli isolates were reclassified as A equuli subsp haemolyticus, emphasizing the importance of toxin genotyping in accurate classification of actinobacilli. 相似文献
66.
67.
Kloss S Wehrend A Failing K Bostedt H 《Berliner und Münchener tier?rztliche Wochenschrift》2002,115(7-8):247-251
The incidence of dystocia from ewes in nine lambing periods (1992-2000) was recorded at an obstetrical clinic. First we analysed parturition difficulties in normal pregnant sheep (group 1, n = 229). In the second group parturitions of ewes with vaginal prolapse ante partum were investigated (n = 129). In group 1 maternal causes of dystocia occurred more often than fetal ones (50% maternal, 45% fetal). In maternal parturition difficulties ringwomb was the dominating reason (64%), while abnormal presentations, position and/or posture of the lambs occurred most frequently in fetal dystocia (67%). But there was no statistical influence of age and number of parturitions in both groups. The average of the first notice of prolapsed vaginal tissue was 11 days before lambing. There was a predominance in the affection of sheep at first and second pregnancy (52%). Only 26% of the group 2 sheep had a spontaneous delivery. In 58% of the cases a dystocia was diagnosed. A preterm caesarean section had carried out in 12%, five ewes died before parturition because of septicemia (4%). Sheep suffering from vaginal prolapse ante partum showed maternal caused dystocia significant more frequently than members of group 1 (p < 0.001), with ringwomb as dominating reason (70%). The number of born lambs was significant higher in group 2 than in group 1 (p = 0.019). 相似文献
68.
Single-step purification and evaluation of recombinant BP26 protein for serological diagnosis of Brucella ovis infection in rams 总被引:1,自引:0,他引:1
Zygmunt MS Baucheron S Vizcaino N Bowden RA Cloeckaert A 《Veterinary microbiology》2002,87(3):213-220
To investigate the value of the BP26 protein in the serological diagnosis of ovine brucellosis caused by Brucella ovis, recombinant BP26 protein was produced in Echerichia coli and purified for use in an indirect enzyme-linked immunosorbent assay (I-ELISA). The majority of the recombinant protein was recovered from the supernatant of sonicated recombinant E. coli cells in a soluble form. This facilitated the purification of the recombinant BP26 protein which was achieved by using ion-exchange chromatography. After one step of purification, the purity of the recombinant BP26 protein was analyzed by using SDS-PAGE, Coomassie blue staining, and Western blot with a monoclonal antibody (MAb) directed against the BP26 protein. The degree of purity appeared satisfactory so that it could be directly used in I-ELISA. Although the recombinant BP26-ELISA appeared less useful than I-ELISA using the B. ovis hot saline (HS) extract as antigen, the high number of sera from B. ovis infected rams found positive (90%) in the recombinant BP26-I-ELISA indicated that the BP26 protein may be an additional suitable antigen for serological diagnosis of B. ovis infection in rams. 相似文献
69.
70.
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