We compared membrane thickness of fully developed eggs with those of non-developed eggs in different endangered falcon taxa.
To our knowledge, membrane thickness variation during development has never been examined before in falcons or any other wild
bird. Yet, the egg membrane constitutes an important protective barrier for the developing embryo. Because eggshell thinning
is a general process that occurs during bird development, caused by calcium uptake by the embryo, eggs are expected to be
less protected and vulnerable to breakage near the end of development. Thus, egg membranes could play an important protective
role in the later stages of development by getting relatively thicker. We used linear mixed models to explore the variation
in membrane thickness (n = 378 eggs) in relation to developmental stage, taxon, female age, mass and identity (73 females), egg-laying sequence (105
clutches) and the study zone. Our results are consistent with the prediction that egg membranes are thicker in fully developed
eggs than in non-developed eggs, suggesting that the increase in membrane thickness during development may compensate for
eggshell thinning. In addition, our data shown that thicker membranes are associated with larger, heavier and relatively wider
eggs, as well as with eggs that had thinner eggshells. Egg-laying sequence, female age and the study zone did not explain
the observed variation of membrane thickness in the falcon taxa studied. As we provide quantitative data on membrane thickness
variation during development in falcons not subjected to contamination or food limitation (i.e. bred under captive conditions),
our data may be used as a reference for studies on eggs from natural populations. Considering the large variation in membrane
thickness and the multiple factors affecting on it and its importance in the protection of the embryo, we encourage other
researchers to include measurements on membranes in studies exploring eggshell thickness variation. 相似文献
The vine mealybug (VM) females collected in Israel produce two sex pheromone compounds: lavandulyl senecioate (LS) and (S)-lavandulyl isovalerate (LI). The males display ambiguous behavior to LI: repulsion in the vineyard and attraction of laboratory-reared
males. We addressed the question of individual male behavior, i.e., do males respond to both LS and LI, or might they display
a distinct response to each of the two pheromone compounds. We compared male pherotype frequencies between wild-caught and
laboratory-reared populations. Then, we examined the relationship between pherotype composition and male capture rates in
pheromone traps. Finally, we addressed the heredity of the pherotypes. The Israeli VM populations contain nine different male
pherotypes, as defined according to the male behavior to pheromone compounds. The studied Portuguese populations included
five of the nine pherotypes; none of the Portuguese males were attracted to LI. It seems that the high frequency of males
that were attracted to LI is related to dense VM populations. It is hypothesized that selection for the male pherotypes, I
males, those that respond to LI, occur under high-density rearing conditions. This may result from shorter development times
of males and females that produce more I male pherotypes. The lower relative frequency of trapping of males in LI-baited traps
than expected from the percentage determined in a Petri dish arena suggests that males that respond solely to LS (S males)
are better fliers. The results also suggest that the pherotype trait is inherited by both sexes of the VM. 相似文献
Quantitative meta-analyses of randomized clinical trials investigating the specific therapeutic efficacy of homeopathic remedies
yielded statistically significant differences compared to placebo. Since the remedies used contained mostly only very low
concentrations of pharmacologically active compounds, these effects cannot be accounted for within the framework of current
pharmacology. Theories to explain clinical effects of homeopathic remedies are partially based upon changes in diluent structure.
To investigate the latter, we measured for the first time high-field (600/500 MHz) 1H T1 and T2 nuclear magnetic resonance relaxation times of H2O in homeopathic preparations with concurrent contamination control by inductively coupled plasma mass spectrometry (ICP-MS).
Homeopathic preparations of quartz (10c–30c, n = 21, corresponding to iterative dilutions of 100−10–100−30), sulfur (13x–30x, n = 18, 10−13–10−30), and copper sulfate (11c–30c, n = 20, 100−11–100−30) were compared to n = 10 independent controls each (analogously agitated dilution medium) in randomized and blinded experiments. In none of the
samples, the concentration of any element analyzed by ICP-MS exceeded 10 ppb. In the first measurement series (600 MHz), there
was a significant increase in T1 for all samples as a function of time, and there were no significant differences between homeopathic potencies and controls.
In the second measurement series (500 MHz) 1 year after preparation, we observed statistically significant increased T1 relaxation times for homeopathic sulfur preparations compared to controls. Fifteen out of 18 correlations between sample
triplicates were higher for controls than for homeopathic preparations. No conclusive explanation for these phenomena can
be given at present. Possible hypotheses involve differential leaching from the measurement vessel walls or a change in water
molecule dynamics, i.e., in rotational correlation time and/or diffusion. Homeopathic preparations thus may exhibit specific
physicochemical properties that need to be determined in detail in future investigations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
Several species of Tenebrionidae are stored-grain pests. Since they belong to a specious family, the systematics of these beetles is still in doubt. In insects, spermatogenesis and the spermatozoa exhibit great diversity, and are therefore commonly used in phylogenetic and taxonomic analyses. During the spermatogenetic process in these organisms, the cells originating from a single spermatogonium develop synchronically in groups referred to as cysts. At the end of this process, there is usually only one sperm bundle per cyst, with all the cells in the same orientation. This paper details the spermiogenesis of the tenebrionid beetles Tenebrio molitor, Zophobas confusa, Tribolium castaneum and Palembus dermestoides using whole mount and histological sections of the cysts. In these species, spermatogenesis is similar to that which occurs in most insects. However, during spermiogenesis, the nuclei of the spermatids migrate to two opposite regions at the periphery of the cyst, leading to the uncommon formation of two bundles of spermatozoa per cyst. This feature is possibly an apomorphy for Tenebrionidae. 相似文献
Environmental and ecological degradation can be monitored by biological indicators such as plants, yet little research has been done using subterranean organisms such as collembola, especially in cities. Collembola, a soil fauna group, can be used to assess soil quality and to decipher assembly rules of soil organisms in cities. Here, we review 75 articles on soil collembola in an urban context. We found that soil properties and landscape characteristics influenced soil communities. There is a need for more connectivity between green urban spaces to allow the dispersion of collembola. Little information is available on the assembly of collembola communities, on biotic interactions and on dynamics of colonisation.
Environmental Science and Pollution Research - In this work, a cylindrical flow-through electro-Fenton reactor containing graphite felt electrodes and an Fe(II) loaded resin was evaluated for the... 相似文献
Environmental Science and Pollution Research - Pesticides have been used to kill pests such as insects, fungi, rodents, and unwanted plants. Since these compounds are potentially toxic to the... 相似文献
Environmental Science and Pollution Research - The time of concentration (Tc) is the main hydrological parameter used to characterize the response of a given Hydrological Response Unit (HRU) to a... 相似文献