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101.
102.
Plant Systematics and Evolution - 相似文献
103.
Estênio Guimar?es Paiva Chandra Salgado-Kent Marthe Monique Gagnon Iain Parnum Robert McCauley 《PloS one》2015,10(5)
Research involving marine mammals often requires costly field programs. This paper assessed whether the benefits of using cameras outweighs the implications of having personnel performing marine mammal detection in the field. The efficacy of video and still cameras to detect Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Harbour (Western Australia) was evaluated, with consideration on how environmental conditions affect detectability. The cameras were set on a tower in the Fremantle Port channel and videos were perused at 1.75 times the normal speed. Images from the cameras were used to estimate position of dolphins at the water’s surface. Dolphin detections ranged from 5.6 m to 463.3 m for the video camera, and from 10.8 m to 347.8 m for the still camera. Detection range showed to be satisfactory when compared to distances at which dolphins would be detected by field observers. The relative effect of environmental conditions on detectability was considered by fitting a Generalised Estimation Equations (GEEs) model with Beaufort, level of glare and their interactions as predictors and a temporal auto-correlation structure. The best fit model indicated level of glare had an effect, with more intense periods of glare corresponding to lower occurrences of observed dolphins. However this effect was not large (-0.264) and the parameter estimate was associated with a large standard error (0.113). The limited field of view was the main restraint in that cameras can be only applied to detections of animals observed rather than counts of individuals. However, the use of cameras was effective for long term monitoring of occurrence of dolphins, outweighing the costs and reducing the health and safety risks to field personal. This study showed that cameras could be effectively implemented onshore for research such as studying changes in habitat use in response to development and construction activities. 相似文献
104.
Marthe Rizk-Rabin Rougui Zineb Bouizar Zhor Garabedian Michele Pavlovitch Jana 《Journal of cellular physiology》1994,159(1):131-141
The epidermis is both a target tissue for and a source of 1,25 dihydroxycholecal-ciferol. The present study determines which of the epidermal cell populations synthesizes 1,25 dihydroxycholecalciferol and which responds to this hormone. Epidermal keratinocytes from new born rat epidermis were separated by unit gravity sedimentation into poorly differentiated cells, slow-cycling more differentiated cells, actively proliferating cells, and terminally differentiating subpopulations. The keratinocyte populations were characterized by cell size analysis, cell morphology, and DNA and RNA contents (acridine orange flow cytometry). 1,25(OH)2D3 synthesis was studied by measuring the conversion of [3H] 25(OH)D3 to [3H] 1,25(OH)2D3. The purified product was tested for its ability to compete with synthetic [3H] 1,25(OH)2D3 for binding to chick intestinal cytosol. The responses of the keratinocyte subpopulations to exogeneous 1,25(OH)2D3 were evaluated by the increase in 25(OH)D3-24 hydroxylase activity. Furthermore the expression of 1,25(OH)2D3 receptors (VDR) was examined in these cell populations. The results show that only the least differentiated cells produced 1,25(OH)2D3. In contrast, immunocytochemical detection of VDR, the VDR mRNA, and a 25(OH)D3-24 hydroxylase response to 1,25(OH)2D3 were mainly found in the more differentiated cells. Thus, the ability of epidermis to synthesize 1,25(OH)2D3 and be simultaneously sensitive to it depends on the state of cell differentiation. This suggests that the mammalian epidermis contains a paracrine system in which the more differentiated keratinocytes are sensitive to the 1,25(OH)2D3 produced locally by neighboring immature ones. © 1994 wiley-Liss, Inc. 相似文献
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The hormonal form of vitamin D appears to be a physiological regulator of the epidermogenesis. While its differentiation-promoting effect is well accepted, there are conflicting reports of its action on keratinocyte proliferation. This study evaluates the specific changes induced by vitamin D treatment in the epidermis of rats nutritionally deprived of vitamin D by cell size analysis, acridine orange flowcytometry, and the immunohistochemical detection of proteins related to the different stages of differentiation (epidermal calcium binding protein and suprabasal keratins recognized by KL1 antibody) The total keratinocyte and isolated keratinocyte subpopulations were studied. Vitamin D deficiency was associated in the total population with a lower percentage of actively proliferating cells and with a lack of differentiation markers. Study of the isolated cell populations demonstrated, however, that small cells were actively proliferating, whereas they were mainly in the resting stage in the normal epidermis. Treatment with vitamin D dramatically increased cell proliferation and stimulated the appearance of differentiation markers. Some of the observed effects, such as an increase in proliferation and the appearance of epidermal calcium binding protein, were due to the normalisation of the vitamin D deficiency-induced hypocalcemia, whereas the expression of suprabasal keratins was directly dependent on vitamin D. We conclude that the action of vitamin D on the epidermis is associated with increases in both proliferation and differentiation of keratinocytes. Vitamin D itself and its resulting action on calcium homeostasis appear to contribute to the observed effects. © 1996 Wiley-Liss, Inc. 相似文献
107.
Elevated major ions (or salinity) are recognised as being a key contributor to the toxicity of many mine waste waters but the complex interactions between the major ions and large inter-species variability in response to salinity, make it difficult to relate toxicity to causal factors. This study aimed to determine if the toxicity of a typical saline seepage water was solely due to its major ion constituents; and determine which major ions were the leading contributors to the toxicity. Standardised toxicity tests using two tropical freshwater species Chlorella sp. (alga) and Moinodaphnia macleayi (cladoceran) were used to compare the toxicity of 1) mine and synthetic seepage water; 2) key major ions (e.g. Na, Cl, SO4 and HCO3); 3) synthetic seepage water that were modified by excluding key major ions. For Chlorella sp., the toxicity of the seepage water was not solely due to its major ion concentrations because there were differences in effects caused by the mine seepage and synthetic seepage. However, for M. macleayi this hypothesis was supported because similar effects caused by mine seepage and synthetic seepage. Sulfate was identified as a major ion that could predict the toxicity of the synthetic waters, which might be expected as it was the dominant major ion in the seepage water. However, sulfate was not the primary cause of toxicity in the seepage water and electrical conductivity was a better predictor of effects. Ultimately, the results show that specific major ions do not clearly drive the toxicity of saline seepage waters and the effects are probably due to the electrical conductivity of the mine waste waters. 相似文献
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de Muizon Capucine Jourdain Iandolo Donata Nguyen Dung Kim Al-Mourabit Ali Rousseau Marthe 《Marine biotechnology (New York, N.Y.)》2022,24(5):831-842
Marine Biotechnology - Nacre, also called mother-of-pearl, is a naturally occurring biomineral, largely studied by chemists, structural biologists, and physicists to understand its outstanding and... 相似文献
110.
Jessica D. Arden Kari I. Lavik Kaitlin A. Rubinic Nicolas Chiaia Sadik A. Khuder Marthe J. Howard Andrea L. Nestor-Kalinoski Arthur S. Alberts Kathryn M. Eisenmann 《Molecular biology of the cell》2015,26(21):3704-3718
The extensive invasive capacity of glioblastoma (GBM) makes it resistant to surgery, radiotherapy, and chemotherapy and thus makes it lethal. In vivo, GBM invasion is mediated by Rho GTPases through unidentified downstream effectors. Mammalian Diaphanous (mDia) family formins are Rho-directed effectors that regulate the F-actin cytoskeleton to support tumor cell motility. Historically, anti-invasion strategies focused upon mDia inhibition, whereas activation remained unexplored. The recent development of small molecules directly inhibiting or activating mDia-driven F-actin assembly that supports motility allows for exploration of their role in GBM. We used the formin inhibitor SMIFH2 and mDia agonists IMM-01/-02 and mDia2-DAD peptides, which disrupt autoinhibition, to examine the roles of mDia inactivation versus activation in GBM cell migration and invasion in vitro and in an ex vivo brain slice invasion model. Inhibiting mDia suppressed directional migration and spheroid invasion while preserving intrinsic random migration. mDia agonism abrogated both random intrinsic and directional migration and halted U87 spheroid invasion in ex vivo brain slices. Thus mDia agonism is a superior GBM anti-invasion strategy. We conclude that formin agonism impedes the most dangerous GBM component—tumor spread into surrounding healthy tissue. Formin activation impairs novel aspects of transformed cells and informs the development of anti-GBM invasion strategies. 相似文献