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61.
Anders Pape Mller 《Ethology : formerly Zeitschrift fur Tierpsychologie》1988,78(4):321-331
The temporal and spatial distribution of song was studied in a population of yellowhammers Emberiza citrinella. Song was most frequent during the breeding season, and within the breeding season during the fertile period of both first, second, and replacement clutches. Song activity peaked at sunrise and sunset. During the fertile period most singing took place in the central parts of the territory. Song post heights peaked during the fertile period, and more song posts lacked foliage at that time. Intrusions by male conspecifics peaked in the fertile period and in territories where males sang relatively little. Song activity and mate guarding were strongly positively correlated. Song volume was loud and song was thus apparently used in long-distance communication. These observations are in accordance with a male deterrence hypothesis, suggesting that males sing to deter neighbouring males from trespassing during the fertile period of their mate. A female attraction hypothesis, suggesting that males sing to attract neighbouring females and thereby obtain extra-pair copulations, and a female reproduction hypothesis, suggesting that males sing to start the female reproductive cycle, were partly supported by observations. 相似文献
62.
Behavioral responses of a sex-role reversed pipefish to a gradient of perceived predation risk 总被引:5,自引:4,他引:1
Conspicuous behaviors such as courtship and mating often makeanimals susceptible to predation. When perceiving themselvesat an elevated level of risk, animals frequently reduce conspicuousbehaviors in tradeoff for a decrease in probability of beingpreyed upon. In the present study, we used two experiments toexamine the effect of perceived predation risk from cod (Gadusmorhud) on nonreproductive and reproductive behaviors in thesex-role reversed pipefish (Syngnathus typhle). In the firstexperiment, no differences due to predation risk were detectedin the nonreproductive behaviors of either males or females.In the second experiment, predation risk had significant effectson reproductive behaviors. Pipefish were allowed to court andcopulate at four different predation levels. We created predationlevels differing in perceived predation risk by controllingthe number of sensory modes through which pipefish could detectthe presence of a cod. As predation risk increased, pipefishcopulated and courted less frequently, swam alone (displayedand searched for conspecifics) less often, and waited longerbefore commencing courtship. These changes in behavior minimizedthe amount of time spent above the eelgrass and presumably reducedconspicuousness to visual predators. Pipefish also copulatedafter a smaller amount of courtship as predation risk increased,indicating that they may trade information concerning mate qualityfor a reduction in predation risk. No differences were foundin any response variable between males and females. The roleof operational sex ratios and intersexual competition in determiningwhich sex assumes greater costs in mate acquisition is questioned. 相似文献
63.
Allan Sirsj Kerstin rstrand Bertil K gedal G ran Nylander Anders Gidl f 《Free radical research》1996,25(5):385-391
Microdialysis probes were inserted into the tibialis anterior muscle and into the femoral vein of anaesthetised Sprague-Dawley rats for monitoring of reduced (GSH) and oxidized (GSSG) extracellular glutathione. The dialysates were analysed using HPLC. The levels of GSH and GSSG were high immediately after implantation in the skeletal muscle and declined to steady state levels after 90 minutes into the same range as that found in the venous dialysate. Total ischemia was induced two hours after implantation of the dialysis probe after steady state levels had been reached. The extracellular levels of GSH increased during total ischemia and had doubled at the end of the ischemic period compared to preischemic values. During the following initial 30 minutes of reperfusion the levels increased further to four-fold the preischemic levels. The levels of GSSG also increased (100%) during the initial 30 minutes of reperfusion. The extracellular GSH levels remained elevated for 1 hour of reperfusion, but the GSSG levels returned to preischemic levels. The results indicate that intermittent hypoxia or anoxia in muscle tissue through hypoperfusion or ischemia decreases intracellular GSH stores by leakage, reducing the intracellular antioxidative capacity and increasing the risk for oxidative reperfusion injury upon final normalization of tissue blood supply. 相似文献
64.
Katarina Jansson Gunnar Kratz Anders Haegerstrand 《In vitro cellular & developmental biology. Animal》1996,32(9):534-540
Summary Reepithelialization of artificial partial thickness wounds made in biopsies of human skin was determined after 3, 5, or 7
d of incubation, submerged or elevated to the air-liquid interface. The biopsies were reepithelialized within 5–7 d, with
a more complete epidermal healing in wounds exposed to air. Both types of wounds showed similar time-course in deposition
of basement membrane components, as detected by immunofluorescence labeling. Laminin and collagen type VII were deposited
underneath the migrating tips, whereas collagen type IV was detected after reepithelialization. Markers of terminal differentiation
showed a pattern close to normal in the air-liquid incubated wounds after reepithelialization. Involucrin was detected in
the suprabasal regions of the migrating epidermis and thereafter in the upper half of neo-epidermis in the air-liquid incubated
wound. Filaggrin could not be detected in the submerged wounds at any time during healing, whereas wounds exposed to air showed
a well-differentiated epidermis by Day 7. Tritiated thymidine-incorporation indicated proliferation of epidermal and dermal
cells during reepithelialization and a maintained viability, as shown by cultivation of endothelial- and fibroblast-like cells
obtained from the dermis 7 d after wounding.
Reepithelialization in this humanin vitro model is supported by a matrix close to normal with the possibility of extracellular influences and cell-cell interactions
and, in addition, the technique is simple and reproducible. Therefore, we suggest this model for studies of regeneration in
culture and as a complement toin vivo studies on epidermal healing. 相似文献
65.
Characterization of rapeseed myrosinase-binding protein 总被引:12,自引:0,他引:12
Myrosinase-binding proteins (MBPs) were purified from seeds of Brassica napus L. (oilseed rape). The proteins were characterized with respect to amino-acid composition, peptide sequence and isoelectric points. Gel electrophoresis and Western blotting of protein extracts from mature seeds showed the existence of at least ten proteins reacting with a monoclonal anti-MBP antibody and ranging in molecular size from 110 to 30 kDa. Proteins other than MBP reacting with the anti-MBP antibody were assigned as myrosinase-binding protein-related proteins (MBPRPs). Two MBPRPs were purified by immunoaffinity chromatography and characterized with respect to partial amino-acid sequence. Sequence identities were found between MBP and MBPRP. Western blot analysis of protein extracts from different tissues of B. napus showed that MBPRP is present in the whole plant, whereas MBP mostly occurs in the mature seed. A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was used to investigate the occurrence of MBP and MBPRP in developing seeds of some species in the Brassicaceae family.Abbreviations FPLC
fast protein liquid chromatography
- MBP
myrosinase-binding protein
- MBPRP
myrosinase-bindingprotein-telated protein
- PBS
phosphate-buffered saline 相似文献
66.
Abstract: Prostaglandin E2 (PGE2) delivered to the spinal cord produces an increased sensitivity to noxious (hyperalgesia) and innocuous (allodynia) stimuli. The mechanisms that underlie this effect remain unknown, but a PGE2-evoked enhancement of spinal neurotransmitter release may be involved. To address this hypothesis, we examined the effect of PGE2 on CSF concentrations of amino acids and also the modulatory effect of PGE2 on capsaicin-evoked changes of spinal amino acid concentrations using a microdialysis probe placed in the lumbar subarachnoid space. Amino acids were quantified using HPLC with fluorescence detection. Addition of 1 mM, but not 10 or 100 µM, PGE2 to the perfusate for a 10-min period (flow rate, 5 µl/min) evoked an immediate increase (80–100%) in glutamate (Glu), aspartate (Asp), taurine (Tau), glycine (Gly), and γ-aminobutyric acid (GABA) concentrations. Similarly, capsaicin infusion (0.1–10 µM) induced a dose-dependent increase in Glu, Asp, Tau, Gly, GABA, and ethanolamine levels. Significant increases in amino acid levels evoked by PGE2 or capsaicin were associated with a touch-evoked allodynia. The combination of PGE2 (10 µM) and capsaicin (0.1 or 1.0 µM) at concentrations that individually had no effect together evoked a significant increase (60–100%) in Glu, Asp, Tau, Gly, and GABA concentrations and produced tactile allodynia. These data demonstrate that spinally delivered PGE2 or capsaicin substantially elevates CSF concentrations of both excitatory and inhibitory amino acids. The capacity of PGE2 to enhance and prolong capsaicin-evoked amino acid concentrations may be one of the mechanisms by which spinal PGE2 produces hyperalgesia and allodynia. 相似文献
67.
68.
Anders Johansson Gran Widmalm Per-Erik Jansson Stephen G. Wilkinson 《Carbohydrate research》1995,270(2):191-199
The structure of the acidic polysaccharide from Serratia marcescens serogroup O1 has been investigated. NMR spectroscopy together with sugar and methylation analysis have been used as well as a uronic acid degradation. The polysaccharide consists of pentasaccharide repeating units having the following structure.
The polysaccharide also contains one equivalent of O-acetyl groups per repeating unit present on, inter alia, a hydroxymethyl group. 相似文献
69.
Gotfredsen Anders; Baksgaard Lene; Hilsted Jannik 《Journal of applied physiology》1997,82(4):1200-1209
Gotfredsen, Anders, Lene Bæksgaard, and Jannik Hilsted.Body composition analysis by DEXA by using dynamically changing samarium filtration. J. Appl. Physiol.82(4): 1200-1209, 1997.Dual-energy X-ray absorptiometry (DEXA)has a high accuracy for body composition analysis but is influenced bybeam hardening and other error sources in the extremes of measurement.To compensate for beam hardening, the Norland XR-36 introduces adynamically changing samarium filtration system, which depends on thecurrent-absorber thickness. With this system we found a good agreement(r = 0.99) between reference andmeasured amounts of tissue or fat percentages in a plastic phantom andin smaller (~0.5-4 kg) and larger (~5-20 kg) piles oftissue (ox muscle and lard). Scans of six healthy volunteers coveredwith combinations of beef and lard (~5-15 kg) showed a goodagreement (r = 0.99) between referenceand DEXA values of added soft tissue mass and fat percentage. Weconclude that the DEXA method (and, in particular, the Norland XR-36using dynamic filtration) has a high accuracy for body compositionanalysis. It has a potential for gaining status as a reference methodin the future and may presently be used as a supplement to thetraditional methods for body composition analysis. 相似文献
70.
Amanda C. J. Vincent Anders Berglund Ingrid Ahnesjö 《Environmental Biology of Fishes》1995,44(4):347-361
Synopsis Synopsis Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialised paternal care: only males aerate, osmoregulate and nourish the developing embryos. Two of the species (Entelurus aequoreus andNerophis ophidion) have simple ventral gluing of eggs on the trunk while three species (Syngnathus acus, S. rostellatus andS. typhle) have fully enclosed brood pouches on their tails. Males of the former species receive eggs from one female while males of the genusSyngnathus receive partial clutches from several females. Sex ratios of adults on the site differed from equal to male-biased to female-biased, according to species.S. typhle were most numerous and were resighted most often. They were present throughout the breeding season whereas there were temporal shifts in the presence of the other species on the meadow and in some sex ratios. Most species occurred in the deeper, denser part of the meadow but there was some habitat separation by species and sex. All species tended to stay low in the eelgrass, primarily coming up above the eelgrass to display and mate. No species showed site fidelity either to a home range or to the meadow, withE. aequoreus adults spending least time on the meadow. Sexual size dimorphism differed: males were larger inS. rostellatus, the same size inS acus and smaller in the other species. Although the species overlap in habitat requirements and breeding season, the only observed interspecific interactions were abortive courtships betweenSyngnathus species. 相似文献