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141.
Martha L. Bohórquez Alonso Jorge Martínez Cotrina David Aguilar Pardo Enrique Font Miguel Molina-Borja 《Journal of Ethology》2010,28(2):305-311
Many vertebrate species show display behaviors when predators are in their vicinity. Some of these displays may inform the
predator of the improbability of capturing the prey (i.e., pursuit-deterrent displays) and are potentially advantageous to
both predator and prey. Here we present data on a tail display performed by Gonatodes albogularis, a diurnal tropical gecko. We performed transect surveys in three habitats near Bogotá in Colombia. Geckos detected during
transects were approached by the observer in a standardized way, and details of their tail-waving displays were recorded.
In control recordings animals were watched from a distant site without approaching them. Results showed sexual differences
in tail-waving display: when approached by the observer, males performed this behavior more frequently than females. We found
no significant differences between males and females in flight-initiation distances and height above the substratum when they
were initially located. Results also showed that males displayed more frequently when approached than when the simulated predator
remained stationary. We interpret these results as evidence that the display functions as a pursuit-deterrent signal to potential
predators. However, as some tail displays were performed in the presence of conspecifics, the display may also have a social
function. 相似文献
142.
The recovery of Lactobacillus bulgaricus was studied in correlation to the kinetics of cell drying. When bacteria were dehydrated at 30 °C, either in the presence
or the absence of sucrose, the drying kinetics corresponds to a Fickean diffusion in correspondence with a short lag time.
In contrast, when the bacteria were dehydrated at 70 °C in the absence of sugar, the kinetics corresponds to an anomalous
diffusion, and the lag time is four to five times higher than that at 30 °C. However, when drying at 70 °C was carried out
in the presence of sucrose, drying kinetics turned into a Fickean process parallel to a substantial decrease in the lag time.
The pattern of water desorption was correlated with the critical water activity. When the drying kinetics corresponds to a
Fickean diffusion, the lag time started to increase at 0.7 water activity, but when the cells were dried at 70 °C, the damage
started at 0.5 water activity. This observation indicates that the drying rate affects the pattern of water desorption, and
it can change the value of critical water activity. These results put into relevance that the cell recovery is due to the
drying history and that the recovery increase produced by sucrose can be related to the maintenance of kinetic barriers for
water desorption. 相似文献
143.
144.
1. Within the range of the given conditions of measuring static and dynamic properties of the rabbit gastrocnemius muscle the following results were obtained: a) the dependence of the maxima of isotonic shortening upon the relative length of the muscle at constant load is linear; b) the parameters of the non-linear dependence of the passive elastic force of the muscle upon its relative length (measured in series) were identified using asymptotic regression; c) the time course of isotonic contractions (at an interval from 0 to 0.3 s after the beginning of stimulation) could be satisfactorily approximated by responses of a linear system to a step-function; d) the time course of isometric contractions (at an interval from 0 to 0.3 s after the beginning of stimulation) could be closely approximated by responses of a linear system to a step-function. 2. The time constants of isotonic and isometric contractions were determined as the parameters of the corresponding linear systems. 3. The maximum rates of the isometric and isotonic contractions were determined as maxima of the first derivatives of the responses of the corresponding models. 4. The experimental set-up made it possible to compare the values of the parameters concomitantly followed at various muscle lengths and at various loads. 相似文献
145.
Eduardo León-Ruiz Purificación Alcázar Eugenio Domínguez-Vilches Carmen Galán 《Aerobiologia》2011,27(1):37-50
The present study sought to determine which of the common Poaceae species in the study area contribute most to the Poaceae
pollen season curve, and to determine the phenological behaviour of the species studied. The different floral phenophases
in thirty-three Poaceae species common in and around the city of Córdoba (SW Iberian Peninsula) were checked periodically
over the period 2004–2006. Results showed that longer phenological ranges were recorded in the coolest and wettest year, and
shorter ranges in the warmest and driest year. Moreover, ranges varied as a function of altitude: populations in lower-lying
areas flowered earlier than those at higher altitudes. The results, taken in conjunction with the findings of preliminary
research into potential pollen production, showed that probably only four of the Poaceae species studied—Dactylis glomerata, Lolium rigidum, Trisetaria panicea and Vulpia geniculata—were major contributors to the Poaceae airborne pollen curve. 相似文献
146.
J Ignacio Andrés Jesús Alcázar José M Alonso Adolfo Díaz Javier Fernández Pilar Gil Laura Iturrino Encarna Matesanz Theo F Meert Anton Megens Victor K Sipido 《Bioorganic & medicinal chemistry letters》2002,12(2):249-253
Following the programme started at Janssen Research Foundation searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of a series of substituted 2-(Dimethylaminomethyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives. The 5-HT(2A), 5-HT(2C) and H(1) receptor affinities as well as the mCPP antagonistic activity of the compounds synthesised is described. 相似文献
147.
148.
Effect of auto-oxidized phospholipids on oxidative enzyme assays based on tetrazolium salt reduction
The influence of auto-oxidized phospholipids on the reduction of the tetrazolium salt MTT coupled to the NAD+-dependent lactate dehydrogenase reaction was studied. The following results were obtained: (1) peroxidized phosphatidylcholine interfered in the time-course of the lactate dehydrogenase-mediated MTT reduction; (2) there was a time-dependent decrease in the hydroperoxide content of phosphatidylcholine vesicles during the incubation; (3) the diminution of phosphatidylcholine hydroperoxides required the presence of all the components of the system except MTT; (4) hydroperoxide diminution and MTT reduction were mediated by the superoxide radical O2-, since both processes were inhibited by superoxide dismutase; (5) EDTA inhibited the hydroperoxide decrease and abolished the interference of peroxidized phosphatidylcholine with MTT reduction. It was concluded that hydroperoxides compete with MTT for the electrons coming from substrate oxidation. The superoxide radical O2- and traces of some contaminating metal ion are involved in the process. This is a potential complication in the study of the effect of lipids on enzymatic activities assayed by the tetrazolium salt method. 相似文献
149.
MariáL. Tomaro Rosalìa B. Frydman Abraham Gutnisky Adriana Sburlati 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,676(1):31-42
Porphobilinogen is the substrate of two enzymes: porphobilinogen deaminase and porphobilinogen-oxygenase. The first one transforms it into the metabolic precursors of heme and the second diverts it from this metabolic pathway by oxidizing porphobilinogen to 5-oxopyrrolinones. Rat blood is devoid of porphobilinogen-oxygenase under normal conditions while it carries porphobilinogen-deaminase activity. When the rats were submitted to hypoxia (pO2 = 0.42 atm) for 18 days, the activity of porphobilinogen-oxygenase appeared at the tenth day of hypoxia and reached the maximum at the 14–16th day. It decreased to a half after 2 days (half-life of the enzyme) and disappeared after 4 days of return to normal oxygen pressure. Porphobilinogen-deaminase activity increased after the first day of hypoxia, reached a maximum at the 14–16th day and did not decrease to normal values until the 15th day after return to normal oxygen pressure. The activities of both prophobilinogen-oxygenase and porphobilinogen-deaminase were induced by administration of erythropoietin. When rats were made anaemic with phenylhydrazine, porphobilinogen-oxygenase activity also appeared in the blood cells. Although the reticulocyte concentration was higher when compared to that obtained under hypoxia, the activities of the oxygenase obtained under both conditions were comparable. Porphobilinogen-deaminase activity was always closely related to the reticulocyte content. The appearance of porphobilinogen-oxygenase under the described erythropoietic conditions was due to a de novo induction of the enzyme, as shown by its inhibition with actinomycin D and cycloheximide. Porphobilinogen-oxygenase as well as porphobilinogen-deaminase were present in the rat bone marrow under normal conditions. Their activities increased in phenylhydrazine treated rats. The properties and kinetics of porphobilinogen-oxygenase from the rat blood and bone marrow were determined and found to differ in several aspects. 相似文献
150.