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排序方式: 共有134条查询结果,搜索用时 187 毫秒
91.
MC Chiale D Montalti MA Flamini P Fernández E Gimeno CG Barbeito 《Biotechnic & histochemistry》2016,91(1):30-37
The uropygial glands of birds are sebaceous organs that contribute to the water-repellent properties of the feather coat. We studied the histological and histochemical characteristics of the uropygial gland of chimango caracara using hematoxylin and eosin (H & E), Gomori´s trichrome, orcein, Gomori´s reticulin, periodic acid-Schiff (PAS), Alcian blue (AB) and a variety of lectins. The gland is composed of two lobes and a papilla with 20 downy feathers. It is surrounded by a capsule of dense connective tissue that contains elastic, reticular and smooth muscle fibers. The papilla is delicate and has two excretory ducts. The gland mass relative to body mass was 0.143%. Both adenomer cells and their secretions were stained with Sudan IV, PAS and AB, and were positive for numerous lectins that indicated the presence of lipids and carbohydrates. Immunohistochemical techniques to detect PCNA confirmed cell proliferation in the basal stratum of the adenomer cells. The lipids and glycoconjugates secreted by the uropygial gland serve numerous functions including protection against microorganisms. 相似文献
92.
Effect of Endosulfan on Azospirillum lipoferum Growth, Morphology, Nitrogenase Activity, and Protein Binding
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The organochlorine Thiodan CE inhibited growth and nitrogenase activity of Azospirillum lipoferum. The active ingredient, Endosulfan, was nonspecifically bound to proteins and mainly adsorbed to the cell envelope with small amounts transported into cytosol. The involvement of the external membrane and cyst formation in protection against hazardous substances is discussed. 相似文献
93.
Identification and characterization of a prevacuolar compartment in stigmas of nicotiana alata 总被引:3,自引:1,他引:2
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The stigmas of the ornamental tobacco plant Nicotiana alata accumulate large quantities of a series of 6-kD proteinase inhibitors (PIs) in the central vacuole that are derived from a 40-kD precursor protein, Na-PI. The sorting information that directs Na-PI to the vacuole is likely to reside in a C-terminal propeptide domain of 25 amino acids that forms an amphipathic alpha helix. Using cell fractionation techniques, we have examined transit of Na-PI through the endomembrane system and have identified a prevacuolar compartment that contains Na-PI with an intact targeting signal. In contrast, the targeting signal is not present on the predominant form of Na-PI in the vacuole. The prevacuolar compartment is marked by the presence of homologs of both the t-SNARE, PEP12p, and the putative vacuolar sorting receptor BP-80. Cross-linking and affinity precipitation studies revealed that Na-PI associates with BP-80 within this compartment, providing in vivo evidence for the function of BP-80 as a sorting receptor for a protein with a C-terminal vacuolar targeting signal. 相似文献
94.
Marlies Cortés María J Fernández‐Aceñero MC Martínez‐Campanario Anna Esteve‐Codina Douglas S Darling Balázs Győrffy Toby Lawrence Douglas C Dean Antonio Postigo 《The EMBO journal》2017,36(22):3336-3355
Accumulation of tumor‐associated macrophages (TAMs) associates with malignant progression in cancer. However, the mechanisms that drive the pro‐tumor functions of TAMs are not fully understood. ZEB1 is best known for driving an epithelial‐to‐mesenchymal transition (EMT) in cancer cells to promote tumor progression. However, a role for ZEB1 in macrophages and TAMs has not been studied. Here we describe that TAMs require ZEB1 for their tumor‐promoting and chemotherapy resistance functions in a mouse model of ovarian cancer. Only TAMs that expressed full levels of Zeb1 accelerated tumor growth. Mechanistically, ZEB1 expression in TAMs induced their polarization toward an F4/80low pro‐tumor phenotype, including direct activation of Ccr2. In turn, expression of ZEB1 by TAMs induced Ccl2, Cd74, and a mesenchymal/stem‐like phenotype in cancer cells. In human ovarian carcinomas, TAM infiltration and CCR2 expression correlated with ZEB1 in tumor cells, where along with CCL2 and CD74 determined poorer prognosis. Importantly, ZEB1 in TAMs was a factor of poorer survival in human ovarian carcinomas. These data establish ZEB1 as a key factor in the tumor microenvironment and for maintaining TAMs’ tumor‐promoting functions. 相似文献
95.
Zusammenfassung Die p-Aminobenzoesäure-Mangelmutante pab 1 von Chlamydomonas reinhardii ist in der Lage, Chloramphenicol anstelle von p-Aminobenzoesäure als Supplementstoff zu verwenden. Es konnte jedoch gezeigt werden, daß die Algen selbst nicht imstande sind, Chloramphenicol zu p-Aminobenzoesäure abzubauen. Der Abbau erfolgt vielmehr spontan ohne Mitwirkung der Organismen, allerdings nur in belichteten Versuchsansätzen und nicht in Dunkelheit.Die Entstehung der p-Aminobenzoesäure geht über p-Nitrobenzaldehyd. Sie erfolgt rasch und reichlich, so daß für die Mutante ein Wachstum ermöglicht wird, das dem Wildtyp-Wachstum in Minimalmedium entspricht.
Investigations on a p-Aminobenzoic auxotrophic mutant of Chlamydomonas reinhardii: Chloramphenicol as a substitute for p-aminobenzoic-acid
Summary The p-aminobenzoic-acid mutant pab 1 of Chlamydomonas reinhardii is able to use chloramphenicol as a supplement instead of p-aminobenzoic-acid. Nevertheless, it could be shown, that the algae are not in the position to reduce chloramphenicol to p-aminobenzoic-acid. On the contrary, the decomposition occurs spontaneously without the participation of the organisms, but only in experimental arrangements, exposed to light.The formation of the p-aminobenzoic-acid works rapidly and a high yield via p-nitrobenzaldehyde. Therefore the growth of the mutant is possible, corresponding to the growth of the wildtype cells in minimal-medium.相似文献
96.
97.
Besides their important contribution to global biodiversity, mangroves provide many services. Nevertheless, due to an increase of human activities and to climate change, in less than 20 years these ecosystems have lost one fifth of their global surface area. In response to this decrease, mangrove reforestation incentives have spread throughout the world. The scientific and societal legitimacy of reforestation actions still remain in question. Focusing on two case studies, the Saloum Delta and Lower Casamance, Senegal, our methodology was mainly based on the analysis of environmental narratives and discourses between 2009 and 2013, and on reforestation campaigns conducted by NGOs. We highlight the complexity of the system of values associated with the mangroves, as well as the positive and negative interactions between the services. Even although the reforestation campaigns were generally successful in terms of reforested surfaces and international visibility, they were poor in terms of biological and cultural diversities and led to spatial injustice. Moreover, the extensive reforestation with a unique mangrove species, Rhizophora mangle, was perceived as means of ‘green grabbing’, and the simultaneous buying of carbon tax by industrial conglomerates induced disempowerment of the local communities. More integrated research programmes must be developed towards the extensive knowledge of the mangroves. 相似文献
98.
Barry A Pepers Menno H Schut Rolf HAM Vossen Gert-Jan B van Ommen Johan T den Dunnen Willeke MC van Roon-Mom 《BMC biotechnology》2009,9(1):50-6
Background
Methodologies like phage display selection, in vitro mutagenesis and the determination of allelic expression differences include steps where large numbers of clones need to be compared and characterised. In the current study we show that high-resolution melt curve analysis (HRMA) is a simple, cost-saving tool to quickly study clonal variation without prior nucleotide sequence knowledge. 相似文献99.
Victoria Cavaliere Daniela L Papademetrio Mario Lorenzetti Pamela Valva María Victoria Preciado Patricia Gargallo Irene Larripa Mariela B Monreal María Laura Pardo Silvia E Hajos Guillermo AC Blanco élida MC álvarez 《Translational oncology》2009,2(1):46-58
Chemotherapy aims to limit proliferation and induce apoptotic cell death in tumor cells. Owing to blockade of signaling pathways involved in cell survival and proliferation, nuclear factor κB (NF-κB) inhibitors can induce apoptosis in a number of hematological malignancies. The efficacy of conventional chemotherapeutic drugs, such as vincristine (VCR) and doxorubicine (DOX), may be enhanced with combined therapy based on NF-κB modulation. In this study, we evaluated the effect of caffeic acid phenylethyl ester (CAPE) and MG-132, two nonspecific NF-κB inhibitors, and conventional chemotherapeutics drugs DOX and VCR on cell proliferation and apoptosis induction on a lymphoblastoid B-cell line, PL104, established and characterized in our laboratory. CAPE and MG-132 treatment showed a strong antiproliferative effect accompanied by clear cell cycle deregulation and apoptosis induction. Doxorubicine and VCR showed antiproliferative effects similar to those of CAPE and MG-132, although the latter drugs showed an apoptotic rate two-fold higher than DOX and VCR. None of the four compounds showed cytotoxic effect on peripheral mononuclear cells from healthy volunteers. CAPE- and MG-132-treated bone marrow cells from patients with myeloid and lymphoid leukemias showed 69% (P < .001) and 25% decrease (P < .01) in cell proliferation and 42% and 34% (P < .01) apoptosis induction, respectively. Overall, our results indicate that CAPE and MG-132 had a strong and selective apoptotic effect on tumor cells that may be useful in future treatment of hematological neoplasias. 相似文献
100.
Maximilian C. R. Buff Florian Sch?fer Bernhard Wulffen Jens Müller Bernd P?tzsch Alexander Heckel Günter Mayer 《Nucleic acids research》2010,38(6):2111-2118
Aptamers that can be regulated with light allow precise control of protein activity in space and time and hence of biological function in general. In a previous study, we showed that the activity of the thrombin-binding aptamer HD1 can be turned off by irradiation using a light activatable ‘caged’ intramolecular antisense-domain. However, the activity of the presented aptamer in its ON state was only mediocre. Here we studied the nature of this loss in activity in detail and found that switching from 5′- to 3′-extensions affords aptamers that are even more potent than the unmodified HD1. In particular we arrived at derivatives that are now more active than the aptamer NU172 that is currently in phase 2 clinical trials as an anticoagulant. As a result, we present light-regulatable aptamers with a superior activity in their ON state and an almost digital ON/OFF behavior upon irradiation. 相似文献