Transcervical cell (TCC) samples have been shown to contain fetal cells amenable to molecular analysis. However, the presence of ‘contaminating’ maternal cells limits their use for prenatal diagnoses. In this report we show that clumps of fetal cells can be isolated from transcervical samples by micromanipulation and tested by fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR). Out of 129 clumps, isolated from mucus aspirates and transcervical lavages from 29 patients, 29 clumps from 11 patients were found to be exclusively of fetal origin as judged by the detection of chromosome 21-specific polymorphic DNA markers and Y-derived DNA sequences by PCR and FISH. One case of a male triploid fetus, diagnosed by the analysis of TCC samples obtained by mucus aspiration and lavage, was confirmed by testing clumps of cells isolated by micromanipulation. 相似文献
Green roofs contribute to both climate change adaptation and mitigation. Promoting green roofs is thus a key element in urban strategies to address climate change. How to actually promote green roofs, however, has so far proven elusive: attempts to link specific policy instruments to a more or less successful diffusion of green roofs have been few and far between. The present paper relies on institutional economics to advance the present understanding of the link between policy instruments and green roofs. It argues that different green roofs are confronted with different social dilemmas, and thus require different policy instruments. Specifically, small green roofs face a free-rider problem, which is best addressed through regulations and incentives. Large green roofs face instead a collective action problem, which is best addressed through communications and network-building. This perspective is tested empirically through a comparative analysis of 18 global cities on the forefront in the promotion of green roofs. The policy instruments observed in these cities match with the theoretical expectations laid down in the paper. Implications emerge for both policy and research.
Conservation and enhancement of ecosystem services have become a priority of rural policies. Feedback loops from rural policies on ecosystem service supply have often been highlighted in the literature, but only vaguely investigated. In this paper, we model feedback loops from rural policies through an agent-based model, and we analyse whether feedback loops can indirectly create a system in which voluntarily landscape enhancement emerges from the interactions between farmers and rural tourists. The results suggest that, in certain conditions, feedback loops from policies can be a relevant element to take into account, but that greater attention to the ecosystem service demand is required. 相似文献
The role that genetic and environmental factors play in triggering neural tube defects in the mouse mutant curly-tail (ct) were investigated by transplanting curly-tail blastocysts into the uterus of either curly-tail females or females of an unrelated A strain with a low natural incidence of abnormalities of the neural tube. The percentages of fetuses with neural tube defects were found to be similar in both groups. These results show that in curly-tail mice exencephaly and spina bifida are manifested independently of the maternal environment. 相似文献
Female ornamentation may be directly sexually selected, by male choice or female competition, or occurs as the result of a
genetic correlation, arising from sexual selection on males. However, increasing evidence supports the former hypothesis,
suggesting that males actively choose their partner preferring traits indicative of female quality. In the lagoon goby, Knipowitschia panizzae, a polygynous species whose males perform parental care to eggs, body length and the size of a sex-specific yellow patch
on the belly are known to be reliable indicators of female fecundity. In this paper, we tested, using dummies, the male’s
mating preferences for female body and yellow belly patch sizes. The two experimental trials in which a single female trait
was variable showed that males prefer a larger belly patch and a larger body size, indicating that both these characters are
selected by male mate choice. However, when faced with dummies exhibiting an inverse combination of body and belly patch sizes
(experiment 3), males significantly preferred the smaller ones with larger yellow belly patches. A calculation of dummy theoretical
fecundity reveals that in the first two experiments, males would have received an immediate benefit from their choice in terms
of egg number, whereas in the third one, males chose partners that would have provided them with fewer eggs. The male lagoon
goby preference for females with larger belly patches, regardless of their size, suggests that this trait, in addition to
indicating fecundity, conveys information about other aspects of female and/or egg quality. 相似文献
Environmental Economics and Policy Studies - We evaluate the effectiveness of attaching microchips to bags for curbside collection in reducing unsorted urban solid waste and increasing the fraction... 相似文献