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31.
Kurt Boonen John W. Creemers Liliane Schoofs 《BioEssays : news and reviews in molecular, cellular and developmental biology》2009,31(3):300-314
Bioactive peptides are a group of diverse intercellular signalling molecules. Almost half a century of research on this topic has resulted in an enormous amount of data. In this essay, a general perspective to interpret all these data will be given. In classical endocrinology, neuropeptides were thought of as simple signalling molecules that each elicit one response. However, the fact that the total bioactive peptide signal is far from simple puts this view under pressure. Cells and tissues express many different bioactive peptides and they are also able to respond to many different bioactive peptides, indicating that multiple receptors and signal transduction pathways are present in a single cell. Therefore, the authors suggest that the bioactive peptide signalling system should be regarded in the context of network and systems biology. Bioactive peptides can best be viewed as an extension of the protein interaction network that allows regulating and fine‐tuning the metabolism of the different cells and tissues in the body. The cell thus responds to the ‘peptidome’ instead of to a single peptide. The intracellular part of this signalling network consists of the various signalling transduction cascades. Recently, new systems biology approaches have emerged for the modelling of cell signalling. The network and systems biology approach is also able to shed new light on the evolution of intercellular signalling. 相似文献
32.
Steve Swinnen Annelies Goovaerts Kristien Schaerlaekens Fran?oise Dumortier Pieter Verdyck Kris Souvereyns Griet Van Zeebroeck María R. Foulquié-Moreno Johan M. Thevelein 《Eukaryotic cell》2015,14(9):884-897
Very high ethanol tolerance is a distinctive trait of the yeast Saccharomyces cerevisiae with notable ecological and industrial importance. Although many genes have been shown to be required for moderate ethanol tolerance (i.e., 6 to 12%) in laboratory strains, little is known of the much higher ethanol tolerance (i.e., 16 to 20%) in natural and industrial strains. We have analyzed the genetic basis of very high ethanol tolerance in a Brazilian bioethanol production strain by genetic mapping with laboratory strains containing artificially inserted oligonucleotide markers. The first locus contained the ura3Δ0 mutation of the laboratory strain as the causative mutation. Analysis of other auxotrophies also revealed significant linkage for LYS2, LEU2, HIS3, and MET15. Tolerance to only very high ethanol concentrations was reduced by auxotrophies, while the effect was reversed at lower concentrations. Evaluation of other stress conditions showed that the link with auxotrophy is dependent on the type of stress and the type of auxotrophy. When the concentration of the auxotrophic nutrient is close to that limiting growth, more stress factors can inhibit growth of an auxotrophic strain. We show that very high ethanol concentrations inhibit the uptake of leucine more than that of uracil, but the 500-fold-lower uracil uptake activity may explain the strong linkage between uracil auxotrophy and ethanol sensitivity compared to leucine auxotrophy. Since very high concentrations of ethanol inhibit the uptake of auxotrophic nutrients, the active uptake of scarce nutrients may be a major limiting factor for growth under conditions of ethanol stress. 相似文献
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35.
Annelies Mortier Eduardo V. Soares 《World journal of microbiology & biotechnology》2007,23(10):1401-1407
Separation of yeast cells using a co-flocculation process was investigated. Co-flocculation is a fast process (within few
minutes), occurs in a broad pH range (3.0–8.0) and requires a small amount of calcium (0.1 mM). Agitation affects yeast aggregation;
however, an agitation between 60 rev/min and 160 rev/min has only a little influence on the co-flocculation process. The ratio
flocculent/non-flocculent cells that induced the settling of 50 and 90% of the cells of S. cerevisiae was 1:7 and 1:1, respectively. Separation of non-flocculent cells can be carried out at any time of the growth cycle. No
difference in the efficiency of co-flocculation carried out in buffer (pH 4.0 with 10 mM calcium) or in 48 h-fermented broth
was observed. Flocculent cells of Saccharomyces cerevisiae had the ability to sediment non-flocculent cells of S. cerevisiae and
Kluyveromyces marxianus, which shows the suitability of the co-flocculation process for separation of different kinds of non-flocculent cells. 相似文献
36.
van der Heijde D Landewé R Boonen A Einstein S Herborn G Rau R Wassenberg S Weissman BN Winalski CS Sharp JT 《Arthritis research & therapy》2007,9(4):R62
The objective of the present study was to test the hypothesis that experts recognize repair of erosions and, if so, to determine
which, if any, morphologic features permitted them to recognize the repair. We also tested whether scoring by a standard method
detected repair. Seven experienced readers of radiographs in rheumatoid arthritis were presented with 64 sets of single joints-of-interest
at two time points, randomized and blinded for the correct sequence. The readers assessed which joint was better, and recorded
whether any of six specific features were seen. Two independent readers, experienced in scoring by the van der Heijde-modified
Sharp method who were not on the expert panel, then scored the complete films that included the joint-of-interest. The panel
agreed very well on which of two joints was better, and, even though they did not know the true sequence, the panel accurately
assigned a sequence slightly better than chance alone (58%) but worse than their agreement on which image was 'better or worse'
(78%). The readers therefore indirectly assigned repair by choosing the second film as the best. Putative repair features
were seen in cases of both repair and progression, and were not discriminatory. Similar results were obtained when the experts
were presented with the entire hand or foot containing the joint-of-interest. In the third repair exercise, two independent
readers who scored whole hands and feet using a standard method found a mean negative score in 22/60 joints-of-interest. All
22 joints were also scored as repair by the panel. Repair was detected reliably by a majority of the panel on viewing paired
images based on a better/worse decision and assigning sequence in a set of images that were blinded for sequence by an independent
project manager. In this test set of images, repair was manifested by a reduction in the size of erosion in many cases. Size
was one feature that aided the experts to detect repair but cannot be the only one; the experts had to find other features
to determine whether a smaller erosion was the first in a sequence of radiographs in a patient with progressive damage or
was the second film in a patient exhibiting repair. The change in size of erosion was also picked up by independent readers
applying the van der Heijde-modified Sharp scoring method and was reflected in their scores. 相似文献
37.
Decru Eva Vranken Nathan Maetens Heleen Mertens De Vry Amber Kayenbergh Annelies Snoeks Jos Van Steenberge Maarten 《Hydrobiologia》2022,849(8):1743-1762
Hydrobiologia - We present an extensive DNA barcoding study of the fish species of the Lake Edward system, including information on intraspecific variation. The DNA barcode gene, cytochrome c... 相似文献
38.
The origin of plant parasitism within the phylum Nematoda is intriguing. The ability to parasitize plants has originated independently at least three times during nematode evolution and, as more molecular data has emerged, it has become clear that multiple instances of horizontal gene transfer (HGT) from bacteria and fungi have played a crucial role in the nematode's adaptation to this new lifestyle. The first reported HGT cases in plant-parasitic nematodes were genes encoding plant cell wall-degrading enzymes. Other putative examples of HGT were subsequently described, including genes that may be involved in the modulation of the plant's defense system, the establishment of a nematode feeding site, and the synthesis or processing of nutrients. Although, in many cases, it is difficult to pinpoint the donor organism, candidate donors are usually soil dwelling and are either plant-pathogenic or plant-associated microorganisms, hence occupying the same ecological niche as the nematodes. The exact mechanisms of transfer are unknown, although close contacts with donor microorganisms, such as symbiotic or trophic interactions, are a possibility. The widespread occurrence of horizontally transferred genes in evolutionarily independent plant-parasitic nematode lineages suggests that HGT may be a prerequisite for successful plant parasitism in nematodes. 相似文献
39.
Vikas SharmaJente Boonen Nagendra S. ChauhanMayank Thakur Bart De SpiegeleerV.K. Dixit 《Phytomedicine》2011,18(13):1161-1169
According to Indian Systems of Medicine, Spilanthes acmella (L.) Murr. (Family - Asteraceae), is considered effective in the treatment of sexual deficiencies especially due to ageing. In the present study, characterization of ethanolic extracts of the Spilanthes acmella flower and its effect on general mating pattern, penile erection and serum hormone levels of normal male Wistar albino rats were investigated and compared with sildenafil citrate. In vitro nitric oxide release was also investigated in human corpus cavernosum cell line. As N-alkylamides are a promising group, their profiling was performed using a gradient reversed phase high performance liquid chromatography/electrospray ionization ion trap mass spectrometry (HPLC/ESI-MS) method on an embedded polar column. MS1 and MS2 fragmentation data were used for identification purposes. For assessment of sexual behavior, animals were divided into five groups of eight male rats. The extracts (50, 100 and 150 mg/kg body weight/day) and sildenafil citrate (5 mg/kg body weight/day) (positive control) were administered orally for 28 days. The behavioral and sexual parameters were observed at days 0, 15, 28 and after a lapse of 7 and 14 days of discontinuance of drug treatment. Five N-isobutylamides, one 2-methylbutylamide and one 2-phenylethylamide were identified. The orally administered extract had a dose dependent positive effect on mounting frequency, intromission frequency and ejaculation frequency and the most significant effects (p < 0.05) were observed at 150 mg/kg treatment, even after a lapse of 7 and 14 days of discontinuance of drug treatment. A dose dependent effect was also observed on the FSH, LH and testosterone serum levels. With 150 mg/kg of ethanolic extract the values for FSH, LH and testosterone were 3.10 ± 0.25 mlU/ml, 6.87 ± 0.18 mlU/ml and 3.72 ± 0.12 ng/ml, respectively. In vitro nitric oxide release was 21.7 ± 2.9 μM, which was significantly higher compared to the control group (p < 0.01). Sildenafil citrate exhibited also a significant effect on NO release, but no effect on hormone levels of rats was observed. The aphrodisiac potential of an ethanolic Spilanthes acmella extract was demonstrated in vitro and in vivo. N-Alkylamides might attribute to the improved sexual potential. Study lends support to the traditional utilization of S. acmella as a sexual stimulating agent. 相似文献
40.
Edmonds A Yotebieng M Lusiama J Matumona Y Kitetele F Napravnik S Cole SR Van Rie A Behets F 《PLoS medicine》2011,8(6):e1001044