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991.
Microbial community succession and bacterial diversity in soils during 77,000 years of ecosystem development 总被引:3,自引:0,他引:3
The origins of the biological complexity and the factors that regulate the development of community composition, diversity and richness in soil remain largely unknown. To gain a better understanding of how bacterial communities change during soil ecosystem development, their composition and diversity in soils that developed over c. 77 000 years of intermittent aeolian deposition were studied. 16S rRNA gene clone libraries and fatty acid methyl ester (FAME) analyses were used to assess the diversity and composition of the communities. The bacterial community composition changed with soil age, and the overall diversity, richness and evenness of the communities increased as the soil habitat matured. When analysed using a multivariate Bray-Curtis ordination technique, the distribution of ribotypes showed an orderly pattern of bacterial community development that was clearly associated with soil and ecosystem development. Similarly, changes in the composition of the FAMEs across the chronosequence were associated with biomarkers for fungi, actinomycetes and Gram-positive bacteria. The development of the soil ecosystem promoted the development of distinctive microbial communities that were reminiscent of successional processes often evoked to describe change during the development of plant communities in terrestrial ecosystems. 相似文献
992.
Structural organization and tooth development in a Homo aff. erectus juvenile mandible from the Early Pleistocene site of Garba IV at Melka Kunture,Ethiopian highlands 下载免费PDF全文
993.
994.
Souza Leandro Cattelan Jesse Cristiano R. de Gomes Marcelo Gomes del Fabbro Lucian Goes André Tiago Rossito Donato Franciele Boeira Silvana Peterini 《Neurochemical research》2017,42(10):2982-2995
Neurochemical Research - There is a lack of information concerning the molecular events underlying the depressive-like effect of an intracerebroventricular injection of streptozotocin (ICV-STZ) in... 相似文献
995.
Vanina A. Fernández Romina Pavé Silvana M. Peker Maria A. Pérez-Rueda 《Acta ethologica》2017,20(1):17-26
We studied the interactions between wild black and gold howler monkeys (Alouatta caraya) and other mammals at three sites with different human disturbance levels and forest structures in northeastern Argentina. The main goal was to evaluate the effects of the study site and type of interaction (agonistic or non-agonistic) on the rate of interaction. In addition, we also described the associations between interspecific interaction rate, species involved, howler monkeys’ activity, and seasonality. We present 50 group-years for 14 groups, collected between 2003 and 2012. We registered a total of 29 interactions (0.22 ± 0.26 interactions/100 h). Most interactions (56.7%) were agonistic (12% of high intensity and 88% of low intensity), 41.9% were neutral, and 1.5% were affiliative. We found that both factors, site and type of interaction, have an effect on the rate of interaction. Interspecific interactions were more frequent at the two sites without human settlement than in the rural site. Interspecific interactions occurred during resting (46.73%), traveling (27.40%), and feeding (25.87%). Interactions occurred throughout the year but were concentrated in August (late winter) and September (beginning of spring). Our results suggest that both site and type of interaction affected the rate of interaction between howler monkeys and other mammals in northeastern Argentina. Agonistic interactions were more frequent that non-agonistic ones, and monkeys reacted agonistically to several mammalian species, but these interactions were mainly of low intensity. 相似文献
996.
In Vitro and In Vivo Differentiation of Progenitor Stem Cells Obtained After Mechanical Digestion of Human Dental Pulp 下载免费PDF全文
997.
Stefano De Benedetti Giorgio Lucchini Cristian Del Bò Valeria Deon Alessandro Marocchi Silvana Penco Christian Lunetta Elisabetta Gianazza Francesco Bonomi Stefania Iametti 《Biometals》2017,30(3):355-365
Amyotrophic lateral sclerosis (ALS) is a fatal disorder with unknown etiology, in which genetic and environmental factors interplay to determine the onset and the course of the disease. Exposure to toxic metals has been proposed to be involved in the etiology of the disease either through a direct damage or by promoting oxidative stress. In this study we evaluated the concentration of a panel of metals in serum and whole blood of a small group of sporadic patients, all living in a defined geographical area, for which acid mine drainage has been reported. ALS prevalence in this area is higher than in the rest of Italy. Results were analyzed with software based on artificial neural networks. High concentrations of metals (in particular Se, Mn and Al) were associated with the disease group. Arsenic serum concentration resulted lower in ALS patients, but it positively correlated with disease duration. Comet assay was performed to evaluate endogenous DNA damage that resulted not different between patients and controls. Up to now only few studies considered geographically well-defined clusters of ALS patients. Common geographical origin among patients and controls gave us the chance to perform metallomic investigations under comparable conditions of environmental exposure. Elaboration of these data with software based on machine learning processes has the potential to be extremely useful to gain a comprehensive view of the complex interactions eventually leading to disease, even in a small number of subjects. 相似文献
998.
Turatti F Figini M Alberti P Willemsen RA Canevari S Mezzanzanica D 《The journal of gene medicine》2005,7(2):158-170
BACKGROUND: Novel antibody-based immunotherapeutic strategies exploit chimeric immune receptors (CIR), expressed on the surface of transduced human peripheral blood mononuclear cells (PBMC), to redirect potent non-MHC-dependent cytotoxicity to tumor cells expressing a tumor-associated antigen. However, clinical application of the strategy has been hampered by the potential side effects associated with immunogenicity and by low transduction efficiency. METHODS: A fully human CIR was constructed that triggers immune activation through the zeta chain of CD3 and contains a human single-chain antibody fragment specific for an extracellular epitope of HER2. PBMC were transduced with the CIR using gibbon-ape leukemia virus envelope pseudotyped retroviruses. In vitro cytotoxicity and inhibition assays were carried out using normal and tumor cell lines expressing different levels of HER2. RESULTS: Bulk populations of CIR-transduced PBMC could express high levels of the construct and subcloning ensured stable expression. CIR-mediated killing and growth inhibition of targets expressing high HER2 levels were very efficient at low effector-to-target ratios. Under the same experimental conditions, CIR-mediated activity against normal cells expressing low HER2 levels was marginal. The CIR-mediated recognition of target cells induced the release of soluble factors able to inhibit growth of both HER-positive and HER2-negative bystander tumor cells. CONCLUSIONS: Human CIR-transduced PBMC exert a potent and dose-dependent anti-tumor activity. Target antigen level appeared to be a critical determinant of specificity and delivery of signals leading to redirected effector functions. Soluble factors, released by redirected effectors at the site of antigen-driven activation, mediate potent bystander killing. 相似文献
999.
Correa SA Pacheco NA Costa-Neto CM Oliveira L Pesquero JB Han SW Paiva AC Shimuta SI 《Regulatory peptides》2005,131(1-3):18-22
To assess the importance of the leucine residues in positions 262 and 265 of the angiotensin AT(1) receptor for signaling pathways and receptor expression and regulation, we compared the properties of CHO cells transfected with the wild type or the L262D or L265D receptor point mutants. It was found that the two mutants significantly increased the basal intracellular cyclic AMP (cAMP) formation in an agonist-independent mode. The morphology transformation of CHO cells was correlated with the increased cAMP formation, since forskolin, a direct activator of adenylate cyclase mimicked this effect on WT-expressing CHO cells. DNA synthesis was found to be inhibited in these cell lines, indicating that cAMP may also have determined the inhibitory effect on cell growth, in addition to the cell transformation from a tumorigenic to a non-tumorigenic phenotype. However a role for an increased Ca2+ influx induced by the mutants in non-stimulated cells cannot be ruled out since this ion also was shown to cause transformed cells to regain the morphology and growth regulation. 相似文献
1000.
Termination of cAMP signals by Ca2+ and G(alpha)i via extracellular Ca2+ sensors: a link to intracellular Ca2+ oscillations 下载免费PDF全文
Gerbino A Ruder WC Curci S Pozzan T Zaccolo M Hofer AM 《The Journal of cell biology》2005,171(2):303-312
Termination of cyclic adenosine monophosphate (cAMP) signaling via the extracellular Ca(2+)-sensing receptor (CaR) was visualized in single CaR-expressing human embryonic kidney (HEK) 293 cells using ratiometric fluorescence resonance energy transfer-dependent cAMP sensors based on protein kinase A and Epac. Stimulation of CaR rapidly reversed or prevented agonist-stimulated elevation of cAMP through a dual mechanism involving pertussis toxin-sensitive Galpha(i) and the CaR-stimulated increase in intracellular [Ca2+]. In parallel measurements with fura-2, CaR activation elicited robust Ca2+ oscillations that increased in frequency in the presence of cAMP, eventually fusing into a sustained plateau. Considering the Ca2+ sensitivity of cAMP accumulation in these cells, lack of oscillations in [cAMP] during the initial phases of CaR stimulation was puzzling. Additional experiments showed that low-frequency, long-duration Ca2+ oscillations generated a dynamic staircase pattern in [cAMP], whereas higher frequency spiking had no effect. Our data suggest that the cAMP machinery in HEK cells acts as a low-pass filter disregarding the relatively rapid Ca2+ spiking stimulated by Ca(2+)-mobilizing agonists under physiological conditions. 相似文献