In this work, we report the use of refractive index (RI) tomography for quantitative analysis of unstained DH82 cell line infected with Leishmania infantum. The cell RI is reconstructed by using a modality of optical diffraction tomography technique that employs partially coherent illumination, thus enabling inherent compatibility with conventional wide‐field microscopes. The experimental results demonstrate that the cell dry mass concentration (DMC) obtained from the RI allows for reliable detection and quantitative characterization of the infection and its temporal evolution. The RI provides important insight for studying morphological changes, particularly membrane blebbing linked to an apoptosis (cell death) process induced by the disease. Moreover, the results evidence that infected DH82 cells exhibit a higher DMC than healthy samples. These findings open up promising perspectives for clinical diagnosis of Leishmania. 相似文献
The Scutellaria is a Labiatae genus (subfamily Scutellarioideae) with a highly specialised floral structure. The genus is characterised by a peculiar two‐lobed calyx with a projecting appendage, named the scutellum. Here, we present a detailed analysis of floral development, using epi‐illumination light microscopy, to clarify open questions about its floral organisation. Floral whorls appeared in an acropetal sequence, with a marked temporal overlap of petal and stamen appearance. Organ appearance in each whorl proceeded unidirectionally from the abaxial to the adaxial side. Significant developmental features included the formation of the scutellum, reduction of sepal lobes and formation of a three‐lobed nectary disc. Our study revealed that both loss of organ initiation and fusion of primordia are responsible for the reduction in sepal members in Scutellaria. The nectary structure was markedly different from most other studied Lamiaceae. 相似文献
Sharing experiences and results among scientists and managers working on seagrass restoration was the main objective of the first European Seagrass Restoration Workshop that gathered researchers from around Europe. The meeting was the first forum in Europe that allowed for scientists, NGOs, and managers to interact and share their experiences relating to seagrass restoration and management. The results show that none of the seagrass restoration programs developed in Europe by the participants during the last 10 years was successful. Furthermore, an informal review of data published in seagrass restoration success, showed that the results reported were biased because they were mostly based on a very short monitoring period (i.e. < 1 year). Numerous decision trees, guidelines, and restoration models have been developed to aid seagrass restoration management, but the results of this workshop point toward a new paradigm in seagrass restoration were efforts should shift to give priority to natural restoration potential, with an emphasis on the fact that restoration should never be considered the first alternative when planning for the mitigation of coastal development projects or to justify mitigation as a compensation measure for economic activities. 相似文献
Major approaches of the Russian Federation in setting of exposure guidelines to electromagnetic fields (EMF) in occupational and public environments are discussed in this paper.
EMF exposure guidelines in Russia are based on the results of hygienic, clinical, physiological, epidemiological and experimental studies and are frequency-dependent. The concept of a threshold principle of occupational and environmental factors due to hazardous exposure effects has been used to set permissible exposure levels of different EMF frequency ranges. The data of experimental studies showed hazardous threshold levels of EMF effects. The main criteria of EMF hazardous exposure evaluated in the experimental study concerned both estimation of threshold levels of chronic (long-term) and acute exposure. Also, this paper contains some recent experimental study data on correlation of long-term radiofrequency and power-frequency EMF exposure effects with regard to time duration, the so-called time-dependence approach. It enables identification of the value of permissible EMF exposure levels depending on exposure duration. This approach is used in occupational exposure guideline setting and requires the introduction of “power exposition” (PE) and “maximal permissible level” (MPL). In general, EMF exposure guidelines are established with regard to possible duration of exposure per day. 相似文献
Different strains of Micrasterias (Chlorophyta, Conjugatophyceae); M. rotata (Grev.) Ralfs ex. Ralfs and M. denticulata Breb. ex. Ralfs var. angulosa (Hantzsch) W. & G. S. West from northern and southern Finland were treated with continuous illumination in order to study the cellular effects of the treatment and whether the tolerance to continuous light of the northern Finnish strains is related to the different daylenght conditions in northern and southern areas. During the growing season the Finnish strains normally live in long-day conditions or even in continuous light (between 60 and 70°N), and they also tolerated continuous illumination in the laboratory. Ultrastructural changes were found especially in the chloroplasts, where formation of calcium precipitates of different forms and sizes and also formation of plastoglobuli containing lipids appeared. However, even in 4-week treatments the ultrastructure of cells of these northern strains was not totally disrupted, contrary to what was found in southern M. torreyi , studied earlier. Southern and northern strains tolerated continuous illumination in different ways. They seem to differ from each other physiologically, and the differences are possibly located in their ionic metabolism and regulation. The injuries sustained during continuous illumination of Micrasterias may largely be caused by the accumulation of Ca2+ in cytoplasm and organelles, especially in the chloroplasts. 相似文献