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81.
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84.
Yonezo Suzuki 《Die Naturwissenschaften》1964,51(23):555-556
85.
86.
Potential synergistic interactions between polycyclic aromatic hydrocarbons in a household sewage sludge compost extract were investigated using the Dioxin-Responsive Chemical-Activated Luciferase gene eXpression (DR-CALUX) assay and reverse-phase high-performance liquid chromatography (RP-HPLC) fractionation. The biological activity of the crude extract was measured in vitro using the CALUX assay. The CALUX activity of the extract was as potent as 360-pg CALUX-TEQ (2,3,7,8-TCDD equivalent value) per g sample, this was 70 times above the WHO-TEQ value which was derived from chemical analyses of dioxins/furans and dioxin-like PCBs of the mixture. The CALUX activity pattern of the crude extract and the retention times of 26 polycyclic aromatic compounds (PACs), as determined by RP-HPLC on an octadecylsilica column, suggested that the dioxin-like compounds with the log K(OW) (n-octanol/water partition coefficient) values corresponding to 6.0-7.0 contributed highly to the whole activity. The CALUX activity of the crude extract was three times the sum of the CALUX activities of the RP-HPLC separated fractions. Mixture effects were assessed by co-exposure of each HPLC fraction and 2,3,7,8-TCDD to the cells. The four concentration levels of added 2,3,7,8-TCDD corresponded to the TEQ value in the original compost sample. The experimental CALUX activity was higher than the predicted CALUX activity for some fractions. It was demonstrated that some compounds in the compost sample interacted synergistically with 2,3,7,8-TCDD in terms of dioxin-like activity. This finding points out the necessity for detailed investigation of synergistic effects in environmental samples. 相似文献
87.
Photoperiodic time measurement is a well-documented adaptation of multicellular plants and animals to seasonal changes in the environment, but it is unclear whether unicellular organisms can exhibit bona fide photoperiodic responses. We demonstrate that the occurrence of zygospore germination of the unicellular alga Chlamydomonas is a genuine photoperiodic response. Germination efficiency is enhanced in long days as compared with short days. While the total amount of light exposure influences the efficiency of germination, the photoperiod is a significant cue for germination. The developmental stage that senses the photoperiod is just prior to mating and during the first days of zygospore development, so there may be a critical window of zygospore maturation that is regulated by photoperiod. Because zygospores are resistant to freezing injury, whereas vegetative cells are not, it is likely that the suppression of germination by short days is an adaptive response for overwintering of Chlamydomonas. Therefore, Chlamydomonas is a single-celled organism that is capable of photoperiodic responses. 相似文献
88.
18S rRNA phylogeny of sea spiders with emphasis on the position of Rhynchothoracidae 总被引:2,自引:1,他引:1
Koichiro?Nakamura Yasunori?KanoEmail author Nobuo?Suzuki Takashi?Namatame Akinori?Kosaku 《Marine Biology》2007,153(2):213-223
The phylogenetic relationships among all living families of sea spiders (Arthropoda: Pycnogonida) are investigated using nearly
complete 18S rRNA sequences from 57 ingroup species and five chelicerates under the Bayesian and maximum likelihood methods.
Monophyly of Colossendeidae, Pycnogonidae, Phoxichilidiidae, Endeidae and Pallenopsidae is consistently supported. However,
the genera formerly classified in the family Ammotheidae are split up into two distantly related groups. The genera Ascorhynchus and Eurycyde (here recognized as Ascorhynchidae) are possibly an early offshoot of sea spiders, whereas other ammotheids constitute a
robust terminal clade with Pallenopsidae, Phoxichilidiidae and Endeidae. This topology also opposes the prevalent assumption
of successive losses and simplification of three kinds of cephalic appendages like in a previous cladistic analysis. At least
three independent losses are suggested for palps by the inferred topology, and both chelifores and female ovigers may have
been lost twice. Our knowledge of early ontogeny and internal anatomy is more congruent with the present 18S rRNA data. The
families Callipallenidae and Nymphonidae with unique “attaching larvae” are grouped together in present molecular trees, suggesting
that extended paternal care of offspring evolved only once in Pycnogonida. Confident clustering of Pycnogonidae and Rhynchothoracidae
indicates that the number of female genital pores is an evolutionary conservative character. 相似文献
89.
Go You-How Lau Lin-Sea Ng Cheong-Fatt Yiew Thian-Hee 《Environmental science and pollution research international》2021,28(45):63968-63976
Environmental Science and Pollution Research - Obesity is a worldwide concern as it leads to adverse effects on human health. This study uses a panel of 165 countries and annual data from 2000 to... 相似文献
90.
Investigation of the possible sources of heavy metal contamination in lagoon and canal water in the tannery industrial area in Dhaka, Bangladesh 总被引:2,自引:0,他引:2