排序方式: 共有52条查询结果,搜索用时 15 毫秒
1.
Harold Gouzoules Sarah Gouzoules Kimran Miller 《International journal of primatology》1996,17(4):549-568
Signalers that misinform sufficiently open may become devalued as sources of information; however, “skepticism” and any comparison
involved in testing reliability entail a cost that involves delays and energy expenditure. Skepticism may be less costly though,
if, as a rule, animals are not equally skeptical of the signals of all conspecifics. Animals with the ability to recognize
individual conspecifics and to recall past encounters with them may have the capacity to restrict skepticism to subsets of
animals that are most likely to benefit from deception. We played tape-recorded alarm calls of high- and low-ranking rhesus
monkeys(Macaca mulatta) to their groups in a feeding context once daily over 8 consecutive days at the Yerkes Primate Center Field Station. Over
the sequence of playbacks, response was greater to the calls of high-ranking monkeys, adult response patterns were different
from those of juveniles, and for adults especially, decline in responsiveness was punctuated by partial resurgences of response.
These differences may be the consequence of the adults’ more extensive histories of interaction with group members that, though
generally reliable, vary with respect to the potential benefits of deceptive signaling. 相似文献
2.
3.
Calcium transients in the cell nucleus evoked by synaptic activity in hippocampal neurons function as a signaling end point in synapse-to-nucleus communication. As an important regulator of neuronal gene expression, nuclear calcium is involved in the conversion of synaptic stimuli into functional and structural changes of neurons. Here we identify two synaptic organizers, Lrrtm1 and Lrrtm2, as targets of nuclear calcium signaling. Expression of both Lrrtm1 and Lrrtm2 increased in a synaptic NMDA receptor- and nuclear calcium-dependent manner in hippocampal neurons within 2–4 h after the induction of action potential bursting. Induction of Lrrtm1 and Lrrtm2 occurred independently of the need for new protein synthesis and required calcium/calmodulin-dependent protein kinases and the nuclear calcium signaling target CREB-binding protein. Analysis of reporter gene constructs revealed a functional cAMP response element in the proximal promoter of Lrrtm2, indicating that at least Lrrtm2 is regulated by the classical nuclear Ca2+/calmodulin-dependent protein kinase IV-CREB/CREB-binding protein pathway. These results suggest that one mechanism by which nuclear calcium signaling controls neuronal network function is by regulating the expression of Lrrtm1 and Lrrtm2. 相似文献
4.
5.
Hayer S Tohidast-Akrad M Haralambous S Jahn-Schmid B Skriner K Trembleau S Dumortier H Pinol-Roma S Redlich K Schett G Muller S Kollias G Smolen J Steiner G 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(12):8327-8336
Human TNF-alpha transgenic (hTNFtg) mice develop erosive arthritis closely resembling rheumatoid arthritis (RA). To investigate mechanisms leading to pathological autoimmune reactions in RA, we examined hTNFtg animals for the presence of RA-associated autoantibodies including Abs to citrullinated epitopes (anti-cyclic citrullinated peptide), heterogeneous nuclear ribonucleoprotein (hnRNP)-A2 (anti-RA33), and heat shock proteins (hsp) (anti-hsp). Although IgM anti-hsp Abs were detected in 40% of hTNFtg and control mice, IgG anti-hsp Abs were rarely seen, and anti-cyclic citrullinated peptide Abs were not seen at all. In contrast, >50% of hTNFtg mice showed IgG anti-RA33 autoantibodies, which became detectable shortly after the onset of arthritis. These Abs were predominantly directed to a short epitope, which was identical with an epitope previously described in MRL/lpr mice. Incidence of anti-RA33 was significantly decreased in mice treated with the osteoclast inhibitor osteoprotegerin and also in c-fos-deficient mice lacking osteoclasts. Pronounced expression of hnRNP-A2 and a smaller splice variant was seen in joints of hTNFtg mice, whereas expression was low in control animals. Although the closely related hnRNP-A1 was also overexpressed, autoantibodies to this protein were infrequently detected. Because expression of hnRNP-A2 in thymus, spleen, brain, and lung was similar in hTNFtg and control mice, aberrant expression appeared to be restricted to the inflamed joint. Finally, immunization of hTNFtg mice with recombinant hnRNP-A2 or a peptide harboring the major B cell epitope aggravated arthritis. These findings suggest that overproduction of TNF-alpha leads to aberrant expression of hnRNP-A2 in the rheumatoid joint and subsequently to autoimmune reactions, which may enhance the inflammatory and destructive process. 相似文献
6.
Birgit G?rtz Silvia Hayer Birgit Tuerck Jochen Zwerina Josef S Smolen Georg Schett 《Arthritis research & therapy》2005,7(5):R1140
Tumour necrosis factor (TNF) is considered to be a major factor in chronic synovial inflammation and is an inducer of mitogen-activated
protein kinase (MAPK) signalling. In the present study we investigated the ability of TNF to activate MAPKs in the synovial
membrane in vivo. We studied human TNF transgenic mice – an in vivo model of TNF-induced arthritis – to examine phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun amino terminal
kinase (JNK) and p38MAPKα in the inflamed joints by means of immunoblot and immunohistochemistry. In addition, the effects
of systemic blockade of TNF, IL-1 and receptor activator of nuclear factor-κB (RANK) ligand on the activation of MAPKs were
assessed. In vivo, overexpression of TNF induced activation of p38MAPKα and ERK in the synovial membrane, whereas activation of JNK was less
pronounced and rarely observed on immunohistochemical analysis. Activated p38MAPKα was predominantly found in synovial macrophages,
whereas ERK activation was present in both synovial macrophages and fibroblasts. T and B lymphocytes did not exhibit major
activation of any of the three MAPKs. Systemic blockade of TNF reduced activation of p38MAPKα and ERK, whereas inhibition
of IL-1 only affected p38MAPKα and blockade of RANK ligand did not result in any decrease in MAPK activation in the synovial
membrane. These data indicate that TNF preferentially activates p38MAPKα and ERK in synovial membrane exposed to TNF. This
not only suggests that targeted inhibition of p38MAPKα and ERK is a feasible strategy for blocking TNF-mediated effects on
joints, but it also shows that even currently available methods to block TNF effectively reduce activation of these two MAPKs. 相似文献
7.
8.
Ember M. Morrissey Rebecca L. Mau Egbert Schwartz Benjamin J. Koch Michaela Hayer Bruce A. Hungate 《Environmental microbiology》2018,20(3):1112-1119
Nitrogen (N) is frequently a limiting nutrient in soil; its availability can govern ecosystem functions such as primary production and decomposition. Assimilation of N by microorganisms impacts the availability of N in soil. Despite its established ecological significance, the contributions of microbial taxa to N assimilation are unknown. Here we measure N uptake and use by microbial phylotypes and taxonomic groups within a diverse assemblage of soil microbes through quantitative stable isotope probing (qSIP) with 15N. Following incubation with 15 , distinct patterns of 15N assimilation among taxonomic groups were observed. For instance, glucose addition stimulated 15N assimilation in most members of Actinobacteria and Proteobacteria but generally decreased 15N use by Firmicutes and Bacteriodetes. While is considered a preferred and universal source of N to prokaryotes, the majority (> 80%) of N assimilation in our soils could be attributed to a handful of active orders. Characterizing N assimilation of taxonomic groups with 15N qSIP may provide a basis for understanding how microbial community composition influences N availability in the environment. 相似文献
9.
Angela M. Hirtreiter Giulia Calloni Francesca Forner Burghardt Scheibe Magda Puype Joel Vandekerckhove Matthias Mann F. Ulrich Hartl Manajit Hayer‐Hartl 《Molecular microbiology》2009,74(5):1152-1168
Chaperonins are macromolecular machines that assist in protein folding. The archaeon Methanosarcina mazei has acquired numerous bacterial genes by horizontal gene transfer. As a result, both the bacterial group I chaperonin, GroEL, and the archaeal group II chaperonin, thermosome, coexist. A proteome‐wide analysis of chaperonin interactors was performed to determine the differential substrate specificity of GroEL and thermosome. At least 13% of soluble M. mazei proteins interact with chaperonins, with the two systems having partially overlapping substrate sets. Remarkably, chaperonin selectivity is independent of phylogenetic origin and is determined by distinct structural and biochemical features of proteins. GroEL prefers well‐conserved proteins with complex α/β domains. In contrast, thermosome substrates comprise a group of faster‐evolving proteins and contain a much wider range of different domain folds, including small all‐α and all‐β modules, and a greater number of large multidomain proteins. Thus, the group II chaperonins may have facilitated the evolution of the highly complex proteomes characteristic of eukaryotic cells. 相似文献
10.