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排序方式: 共有833条查询结果,搜索用时 578 毫秒
781.
782.
Goutham K. Ganjam Jonas Benzler Olaf Pinkenburg Alisa Boucsein Sigrid Stöhr Juliane Steger Carsten Culmsee Perry Barrett Alexander Tups 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2013,183(8):1101-1111
The profound seasonal cycle in body weight exhibited by the Djungarian hamster (Phodopus sungorus) is associated with the development of hypothalamic leptin resistance during long day photoperiod (LD, 16:8 h light dark cycle), when body weight is elevated relative to short day photoperiod (SD, 8:16 h light dark cycle). We previously have shown that this seasonal change in physiology is associated with higher levels of mRNA for the potent inhibitor of leptin signaling, suppressor of cytokine signaling-3 (SOCS3), in the arcuate nucleus (ARC) of LD hamsters relative to hamsters in SD. The alteration in SOCS3 gene expression preceded the body weight change suggesting that SOCS3 might be the molecular switch of seasonal body weight changes. To functionally characterize the role of SOCS3 in seasonal body weight regulation, we injected SOCS3 expressing recombinant adeno-associated virus type-2 (rAAV2-SOCS3) constructs into the ARC of leptin sensitive SD hamsters immediately after weaning. Hamsters that received rAAV2 expressing enhanced green fluorescent protein (rAAV2-EGFP) served as controls. ARC-directed SOCS3 overexpression led to a significant increase in body weight over a period of 12 weeks without fully restoring the LD phenotype. This increase was partially due to elevated brown and white adipose tissue mass. Gene expression of pro-opiomelanocortin was increased while thyroid hormone converting enzyme DIO3 mRNA levels were reduced in SD hamsters with SOCS3 overexpression. In conclusion, our data suggest that ARC-directed SOCS3 overexpression partially overcomes the profound seasonal body weight cycle exhibited by the hamster which is associated with altered pro-opiomelanocortin and DIO3 gene expression. 相似文献
783.
784.
Ana I. Gómez-Varela Ricardo Gaspar Adelaide Miranda Juliane L. Assis Rafael H.F. Valverde Marcelo Einicker-Lamas Bruno F. B. Silva Pieter A.A. De Beule 《Journal of biophotonics》2021,14(1):e202000200
The development of nonviral gene delivery vehicles for therapeutic applications requires methods capable of quantifying the association between the genes and their carrier counterparts. Here we investigate the potential of fluorescence cross-correlation spectroscopy (FCCS) to characterize and optimize the assembly of nonviral cationic liposome (CL)-DNA complexes based on a CL formulation consisting of the cationic lipid DOTAP and zwitterionic lipid DOPC. We use a DNA plasmid for lipoplex loading encoding the Oct4 gene, critically involved in reprogramming somatic cells into induced pluripotent stem cells. We demonstrate that FCCS is able to quantitatively determine the extent of the association between DNA and the liposomes and assess its loading capacity. We also establish that the cationic lipid fraction, being proportional to the liposome membrane charge density, as well as charge ratio between the CLs and anionic DNA play an important role in the degree of interaction between the liposomes and DNA. 相似文献
785.
Hollender Juliane Hopp Johannna Dott Wolfgang 《World journal of microbiology & biotechnology》2000,16(5):445-450
Alcaligenes xylosoxidans subspecies denitrificans JH1 was enriched with 2-chlorophenol from a mixed culture degrading different chloro- and methylphenols. The strain used all monochloro- and monomethylphenols apart from 2-methylphenol as sole source of energy and carbon with stoichiometric release of chloride. 4-Chlorophenol was mineralized up to a concentration of 1.3 mM. Degradation of mixtures of monochloro- and monomethylphenols occurred at least partially except for the mixture of 2-chlorophenol and 3-methylphenol. Depending upon the growth substrates used, enzymes of the ortho and/or meta cleavage pathway catalysed the degradation of the phenols. The transformation of chlorophenols was concluded to occur exclusively via the ortho cleavage pathway because no chlorocatechol 2,3-dioxygenase activity was found in chlorophenol-grown cells. Degradation of 4-methylphenol in strain JH1 occurred both by the ortho and meta cleavage pathway as indicated by the finding that the ortho- and meta-cleaving dioxygenases were expressed in 4-methylphenol-grown cells. Transformation of methylphenols by the ortho cleavage pathway led to the accumulation of methyllactones as dead-end products. Mixtures of methyl- and chlorophenols were metabolized mainly by the ortho cleavage pathway because chlorocatechols formed inactivated the constitutive catechol 2,3-dioxygenase which caused channelling of methylphenols into the ortho cleavage pathway. 相似文献
786.
A new method to affect cells by cell–surface interaction is introduced. Biocompatible magnetic nanobeads are deposited onto
a biocompatible magnetic thin layer. The particles are composed of small magnetite crystals embedded in a matrix which can
be functionalized by different molecules, proteins or growth factors. The magnetic interaction between surface and beads prevents
endocytosis if the setup is utilized for cell culturing. The force acting between particles and magnetic layer is calculated
by a magnetostatic approach. Biocompatibility is ensured by using garnet layers which turned out to be nontoxic and stable
under culturing conditions. The garnet thin films exhibit spatially and temporally variable magnetic domain configurations
in changing external magnetic fields and depending on their thermal pretreatment. Several patterns and bead deposition methods
as well as the cell–surface interactions were analyzed. In some cases the cells show directed growth. Theoretical considerations
explaining particular cell behavior on this magnetic material involve calculations of cell growth on elastic substrates and
bending of cell membranes. 相似文献
787.
788.
Gianluca L. Russo Giovanna Sonsalla Poornemaa Natarajan Christopher T. Breunig Giorgia Bulli Juliane Merl-Pham Sabine Schmitt Jessica Giehrl-Schwab Florian Giesert Martin Jastroch Hans Zischka Wolfgang Wurst Stefan H. Stricker Stefanie M. Hauck Giacomo Masserdotti Magdalena Götz 《Cell Stem Cell》2021,28(3):524-534.e7
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789.
Juliane Liese Ulrike Marzahn Karym El Sayed Axel Pruss Andreas Haisch Katharina Stoelzel 《Cell and tissue banking》2013,14(2):255-266
Tissue Engineering is an important method for generating cartilage tissue with isolated autologous cells and the support of biomaterials. In contrast to various gel-like biomaterials, human demineralized bone matrix (DBM) guarantees some biomechanical stability for an application in biomechanically loaded regions. The present study combined for the first time the method of seeding chondrocyte-macroaggregates in DBM for the purpose of cartilage tissue engineering. After isolating human nasal chondrocytes and creating a three-dimensional macroaggregate arrangement, the DBM was cultivated in vitro with the macroaggregates. The interaction of the cells within the DBM was analyzed with respect to cell differentiation and the inhibitory effects of chondrocyte proliferation. In contrast to chondrocyte-macroaggregates in the cell-DBM constructs, morphologically modified cells expressing type I collagen dominated. The redifferentiation of chondrocytes, characterized by the expression of type II collagen, was only found in low amounts in the cell-DBM constructs. Furthermore, caspase 3, a marker for apoptosis, was detected in the chondrocyte-DBM constructs. In another experimental setting, the vitality of chondrocytes as related to culture time and the amount of DBM was analyzed with the BrdU assay. Higher amounts of DBM tended to result in significantly higher proliferation rates of the cells within the first 48 h. After 96 h, the vitality decreased in a dose-dependent fashion. In conclusion, this study provides the proof of concept of chondrocyte-macroaggregates with DBM as an interesting method for the tissue engineering of cartilage. The as-yet insufficient redifferentiation of the chondrocytes and the sporadic initiation of apoptosis will require further investigations. 相似文献
790.
Juliane Hartke Philipp P. Sprenger Jacqueline Sahm Helena Winterberg Jrme Orivel Hannes Baur Till Beuerle Thomas Schmitt Barbara Feldmeyer Florian Menzel 《Ecology and evolution》2019,9(16):9160-9176
Upon advances in sequencing techniques, more and more morphologically identical organisms are identified as cryptic species. Often, mutualistic interactions are proposed as drivers of diversification. Species of the neotropical parabiotic ant association between Crematogaster levior and Camponotus femoratus are known for highly diverse cuticular hydrocarbon (CHC) profiles, which in insects serve as desiccation barrier but also as communication cues. In the present study, we investigated the association of the ants’ CHC profiles with genotypes and morphological traits, and discovered cryptic species pairs in both genera. To assess putative niche differentiation between the cryptic species, we conducted an environmental association study that included various climate variables, canopy cover, and mutualistic plant species. Although mostly sympatric, the two Camponotus species seem to prefer different climate niches. However in the two Crematogaster species, we could not detect any differences in niche preference. The strong differentiation in the CHC profiles may thus suggest a possible role during speciation itself either by inducing assortative mating or by reinforcing sexual selection after the speciation event. We did not detect any further niche differences in the environmental parameters tested. Thus, it remains open how the cryptic species avoid competitive exclusion, with scope for further investigations. 相似文献