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1.
Symbiont-induced male-killing phenotypes have been found in a variety of insects. Conventionally, these phenotypes have been
divided into two categories according to the timing of action: early male killing at embryonic stages and late male killing
at late larval stages. In Drosophila species, endosymbiotic bacteria of the genus Spiroplasma have been known to cause early male killing. Here, we report that a spiroplasma strain normally causing early male killing
also induces late male killing depending on the maternal host age: male-specific mortality of larvae and pupae was more frequently
observed in the offspring of young females. As the lowest spiroplasma density and occasional male production were also associated
with newly emerged females, we proposed the density-dependent hypothesis for the expression of early and late male-killing
phenotypes. Our finding suggested that (1) early and late male-killing phenotypes can be caused by the same symbiont and probably
by the same mechanism; (2) late male killing may occur as an attenuated expression of early male killing; (3) expression of
early and late male-killing phenotypes may be dependent on the symbiont density, and thus, could potentially be affected by
the host immunity and regulation; and (4) early male killing and late male killing could be alternative strategies adopted
by microbial reproductive manipulators. 相似文献
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3.
Yuuki Miyata Kensuke Miyazaki Masahiro Miura Yasutaka Shimotori Masakazu Aoyama Hisayuki Nakatani 《Journal of Polymers and the Environment》2013,21(1):115-121
A novel solventless delignification of a defatted Picea glehnii wood flour sample was performed using a TiO2/polyethylene oxide (PEO) photocatalyst system. A cell wall structure of the wood flour was directly observed, showing that its lignin fraction was removed by the photodegradation. The total lignin amount was slightly decreased as compared with that of the pristine sample, and the vanillin formation was confirmed by the 1H-NMR measurement. The TiO2 worked as a radical initiator, and simultaneously acid and aldehyde compounds produced by the PEO photolysis did as an accelerator for the solventless delignification. Although the photocatalyst system showed high delignification activity even for a low molecular lignin model, the delignification of the wood flour sample was confined to the surface. It was found that the suppressed delignification behavior was due to crosslinked structure of lignin. 相似文献
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To determine whether the appearance of a reproductively parasitic tactic varies, and how this variation affects territorial
males of the Lake Tanganyika cichlid fish Telmatochromis vittatus, we examined the reproductive ecology of territorial males in Mtondwe and compared it with that of a neighboring Wonzye population,
where nest density differs from that at Mtondwe. In Wonzye, with high nest density, male tactics change with their body size
from a territorial to a non-territorial parasitic tactic called piracy in which they conquer several nests defended by territorial
males and take over the nests while females are spawning. These “pirate” males could decrease the costs incurred by travelling
among nests by exclusively targeting aggregations of nests in close proximity while avoiding separate nests. Territorial males
in Wonzye sacrifice the potential higher attractiveness offered by large nests and instead compete for nests farther from
neighbors on which pirates less frequently intrude. In contrast, the Mtondwe population had lower nest density and piracy
was absent. Given that the success of piracy depends on the close proximity of nests, nest density is likely responsible for
the observed variation in the occurrence of piracy between the two populations. Furthermore, in Mtondwe, territorial males
competed for larger nests and were smaller than the territorial males in Wonzye. Thus, this lower nest density may free territorial
males from the selection pressures for increased size caused by both defense against nest piracy and the need to develop into
pirates as they grow. 相似文献
6.
A sample of commercial BADGE was fractioned by HPLC and eight impurities including novel propyl derivatives (2), (5) and (6) were identified by NMR spectrometry, FAB-MS and GC-MS. The estrogenicity, both agonist and antagonist, of fractions containing these impurities was measured with a yeast two-hybrid assay incorporating the human (hER alpha) and a competitive binding assay for hER alpha (ELISA). In the yeast two-hybrid assay, estrogenic antagonist activity was found in two fractions, while estrogenic agonist activity was not found in any. In the ELISA method, the binding affinity to hER alpha was found in three fractions. It is probable that a comprehensive assessment of the estrogenic properties of commercial BADGE, and their implications for human health, will require examination of all its components as described here. 相似文献
7.
The theoretical basis for matrix diffusion in fractured rocks and the methodology for the determination of diffusion coefficients in the laboratory are well established. One significant problem, however, remains in that it is difficult to quantify the degree of sample disturbance affecting the geometrical, geophysical and hydraulic properties of the rock matrix. A new technique, with in situ rock impregnation with resin, for examining the diffusion-accessible rock matrix has been developed and successfully adopted to the rock matrix behind a water-conducting fracture in host crystalline rocks at Nagra's Grimsel Test Site in Switzerland and JNC's Kamaishi In Situ Test Site in Japan. In line with the results of a large number of natural analogue and laboratory studies, the existence of an in situ interconnected pore network was substantiated. Matrix porosities determined on the laboratory samples from both the sites are 1.5-3 times higher than in situ values, irrespective of the technique applied. On the Grimsel granodiorite matrix, matrix porosity existing in situ and artefacts of stress release and physical disturbance, induced by sampling and sample preparation, were clearly distinguished, allowing in situ porosity to be quantified. Laboratory work with conventional techniques tends to overestimate the porosity of the rock matrix, hence leading to an overestimation of in situ matrix diffusion. The implications of these differences to a repository performance assessment are assessed with a couple of examples from existing assessments, and recommendations for future approaches to the examination of in situ matrix porosity are made. 相似文献
8.
Why are reproductively parasitic fish males so small?—influence of tactic-specific selection 总被引:1,自引:0,他引:1
Despite the wide prevalence of alternative reproductive tactics, little attention has been paid to why reproductively parasitic
males are so small. In this study, we tackled this issue in a shell-brooding fish Lamprologus callipterus. Sneaky ‘dwarf males’ of this fish remain much smaller than bourgeois conspecifics throughout their life and employ a unique
parasitic tactic, i.e. entering into a gastropod shell where a female is spawning, passing through the space between the female
and shell wall and staying behind her to ejaculate throughout the spawning event. Here, we tested the prediction that they
remain small to get past her through the shell spaces by interpopulation comparison. We showed, across populations, a negative
allometry for sexual size dimorphism, an exponential increase of female size with an increase in shell size and a negative
correlation between the magnitude of sexual size dimorphism and shell size. These results suggest that the inner spaces strongly
regulate dwarf male size. We conclude that the small bodies of dwarf males arise from adaptation to their unique reproductive
behaviour. 相似文献
9.
Samal Kaumbekova Mehdi Amouei Torkmahalleh Naoya Sakaguchi Masakazu Umezawa Dhawal Shah 《Frontiers of Environmental Science & Engineering》2023,17(2):15
10.
Behavior and prediction of photochemical degradation of chlorinated polycyclic aromatic hydrocarbons in cyclohexane 总被引:3,自引:0,他引:3
The photochemical degradation of 11 chlorinated polycyclic aromatic hydrocarbons (ClPAHs) and the corresponding 5 parent PAHs was examined to simulate the compound’s fate on aerosol surfaces. All the ClPAHs and PAHs decayed according to the first-order reaction rate kinetics. The photolysis rates of ClPAHs varied greatly according to the skeleton of PAHs; the rates of chlorophenanthrenes (ClPhes) and 1-chloropyrene were higher than those of corresponding parent PAHs, whereas chlorofluoranthenes, 7-chlorobenz[a]anthracene and 6-chlorobenzo[a]pyrene were more stable under irradiation compared to respective parent PAH. Considering the photoproducts of ClPhes detected, the oxidation could occur immediately at positions of the highest frontier electron density. Finally, the quantitative structure-property relationship models were developed for direct photolysis half-lives and average quantum yields of the ClPAHs and parent PAHs, in which the significant factors affecting photolysis were ELUMO+1, total energy and surface area, and ELUMO, ELUMO − EHOMO and total energy, respectively. 相似文献