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1.
Bruce R. Johnson Carl L. Merrill Roy C. Ogle Jelle Atema 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1988,162(2):201-211
1. | A prominent population of olfactory receptor cells from the lobsterHomarus americanus is narrowly tuned to trans-4-hydroxyl-L-proline (Hyp, Fig. 1) suggesting that Hyp may be an important chemical signal for this animal (Johnson and Atema 1983). However, Hyp is usually bound in connective tissue proteins of lobster prey and thus may be unavailable in sufficient quantities as a free amino acid to stimulate chemoreceptors. To determine other possible adequate stimuli for Hyp sensitive cells we further examined their tuning using a variety of substances including other amino acids also found in collagens, Hyp isomers (Fig. 1), synaptic receptor agonists, ecdysones, purified natural collagens and their gelatins (Fig. 2), and different molecular weight fractions of a commercial gelatin solution (Table 1). |
2. | Of a first group of Hyp sensitive cells (N=29) tested with the compounds in Table 1 A, 21 responded best to Hyp. Only a commercial gelatin solution (SG1) and its one-tenth dilution consistently elicited responses from these cells (Fig. 3). The remaining 8 cells responded best to the SG1 solutions (5 cells) or to one of the other test substances (Table 2). |
3. | Of a second group of Hyp sensitive cells (N=27) tested with the collagen and gelatin solutions (Table 1b), 19 responded best to Hyp. Again, the Hyp best cells rarely responded to any test substance other than Hyp and a commercial gelatin solution, SG2, and its greater than 12 kD fraction, SG2-12 (Fig. 4). SG2 and SG2-12 were equally effective for the Hyp best cells. The remaining 8 cells responded best to either SG2 (2 cells), SG2-12 (2 cells) or one of the purified gelatin or collagen solutions (Table 3). |
4. | A third group of Hyp sensitive cells (N=21) was tested with SG2, SG2-12, and a greater than 1 kD fraction of SG2 (SG2-1; Table 1c). Based on the mean response, the most effective stimulus for these cells was SG2-12, followed by SG2-1, SG2 and Hyp. The high mean response for the SG2 solutions was mainly due to a few cells giving large responses to these stimuli (Fig. 6). Ten of these 21 cells responded best to Hyp; all but 2 responded to one or more of the SG2 solutions; the other 11 cells responded best to either SG2, SG2-12 or SG2-1, which were all best stimuli for different cells (Fig. 5). |
5. | Overall, the 77 Hyp sensitive cells tested here can be divided into two main types; 65% Hyp best cells and 31% gelatin best cells. The Hyp best cells seem to be a distinct population of receptors: they have no spontaneous activity and give low responses (15 spikes in 5 s) even to their best stimulus, Hyp. In contrast, the gelatin best cells are not infrequently spontaneously active and can give high responses to their best stimulus (up to 150 spikes in 5 s). In addition, when tested specifically in the third group, the Hyp cells appear to have a tuning spectrum distinct from the gelatin best cells (Fig. 7). |
6. | Stimulation of Hyp cells by gelatin solutions may be due to Hyp-containing peptides derived from the gelatin. Enzymatic tissue breakdown from the lobster's prey could produce chemical mixtures that stimulate prominent receptor populations which respond to both high (gelatin best cells) and low (Hyp best cells) molecular weight substances. This could create a central representation of food based on parallel receptor lines of somewhat overlapping sensitivity. Together, Hyp best and gelatin best receptor cell populations may give important information on the presence and state of decay of the lobster's food. |
2.
Sonja Fuchs Karin Resch Cora Thiel Michael Ulbrich Matthias Platzer Harald Jockusch Thomas Schmitt-John 《BMC genetics》2002,3(1):40
Background
To support the positional cloning of the mouse mutation wobbler (wr ) the corresponding regions on human Chr2p13-14 and mouse Chr11 were analyzed in detail and compared with respect to gene content, order, and orientation. 相似文献3.
Monica Benincasa Chiara Pelillo Sonia Zorzet Chiara Garrovo Stefania Biffi Renato Gennaro Marco Scocchi 《BMC microbiology》2010,10(1):178
Background
Bac7 is a proline-rich peptide with a potent in vitro antimicrobial activity against Gram-negative bacteria. Here we investigated its activity in biological fluids and in vivo using a mouse model of S. typhimurium infection. 相似文献4.
Xiulai Chen Juyang Yi Wei Song Jia Liu Qiuling Luo Liming Liu 《Microbial biotechnology》2021,14(2):392-402
Microbial production of trans-4-hydroxy-l -proline (Hyp) offers significant advantages over conventional chemical extraction. However, it is still challenging for industrial production of Hyp due to its low production efficiency. Here, chassis engineering was used for tailoring Escherichia coli cellular metabolism to enhance enzymatic production of Hyp. Specifically, four proline 4-hydroxylases (P4H) were selected to convert l -proline to Hyp, and the recombinant strain overexpressing DsP4H produced 32.5 g l−1 Hyp with α-ketoglutarate addition. To produce Hyp without α-ketoglutarate addition, α-ketoglutarate supply was enhanced by rewiring the TCA cycle and l -proline degradation pathway, and oxygen transfer was improved by fine-tuning heterologous haemoglobin expression. In a 5-l fermenter, the engineered strain E. coliΔsucCDΔputA-VHb(L)-DsP4H showed a significant increase in Hyp titre, conversion rate and productivity up to 49.8 g l−1, 87.4% and 1.38 g l−1 h−1 respectively. This strategy described here provides an efficient method for production of Hyp, and it has a great potential in industrial application. 相似文献
5.
Peter JI Ellis Lydia Ferguson Emily J Clemente Nabeel A Affara 《BMC evolutionary biology》2007,7(1):171
Background
The male-specific region of the mouse Y chromosome long arm (MSYq) contains three known highly multi-copy X-Y homologous gene families, Ssty1/2, Sly and Asty. Deletions on MSYq lead to teratozoospermia and subfertility or infertility, with a sex ratio skew in the offspring of subfertile MSYqdel males 相似文献6.
Ali Manafi Jamshid Kohanteb Davood Mehrabani Aziz Japoni Masoud Amini Mohsen Naghmachi Ahmad Hosseinzadeh Zaghi Nazanin Khalili 《BMC microbiology》2009,9(1):23-5
Background
Pseudomonas aeruginosa is an important cause of nosocomial infection and may lead to septicemia and death. We evaluated the immunogenicity of semi-purified exotoxin A from the bacterium in a mouse burn model. 相似文献7.
Conditional gene expression in the mouse using a Sleeping Beauty gene-trap transposon 总被引:1,自引:0,他引:1
Aron M Geurts Andrew Wilber Corey M Carlson Paul D Lobitz Karl J Clark Perry B Hackett R Scott McIvor David A Largaespada 《BMC biotechnology》2006,6(1):30-15
Background
Insertional mutagenesis techniques with transposable elements have been popular among geneticists studying model organisms from E. coli to Drosophila and, more recently, the mouse. One such element is the Sleeping Beauty (SB) transposon that has been shown in several studies to be an effective insertional mutagen in the mouse germline. SB transposon vector studies have employed different functional elements and reporter molecules to disrupt and report the expression of endogenous mouse genes. We sought to generate a transposon system that would be capable of reporting the expression pattern of a mouse gene while allowing for conditional expression of a gene of interest in a tissue- or temporal-specific pattern. 相似文献8.
Background
In 2004, Bejerano et al. announced the startling discovery of hundreds of "ultraconserved elements", long genomic sequences perfectly conserved across human, mouse, and rat. Their announcement stimulated a flurry of subsequent research. 相似文献9.
Superoxide dismutase from Helicobacter pylori suppresses the production of pro‐inflammatory cytokines during in vivo infection 下载免费PDF全文
Background
Helicobacter pylori has undergone considerable adaptation to allow chronic persistence within the gastric environment. While H. pylori‐associated diseases are driven by an excessive inflammation, severe gastritis is detrimental to colonization by this pathogen. Hence, H. pylori has developed strategies to minimize the severity of gastritis it triggers in its host. Superoxide dismutase (SOD) is well known for its role in protecting against oxidative attack; less recognized is its ability to inhibit immunity, shown for SOD from mammalian sources and those of some bacterial species. This study examined whether H. pylori SOD (HpSOD) has the ability to inhibit the host immune response to these bacteria.Materials and Methods
The ability of recombinant HpSOD to modify the response to LPS was measured using mouse macrophages. A monoclonal antibody against HpSOD was generated and injected into H. pylori‐infected mice.Results
Addition of HpSOD to cultures of mouse macrophages significantly inhibited the pro‐inflammatory cytokine response to LPS stimulation. A monoclonal antibody was generated that was specific for SOD from H. pylori. When injected into mice infected with H. pylori for 3 months, this antibody was readily detected in both sera and gastric tissues 5 days later. While treatment with anti‐HpSOD had no effect on H. pylori colonization at this time point, it significantly increased the levels of a range of pro‐inflammatory cytokines in the gastric tissues. This did not occur with antibodies against other antioxidant enzymes.Conclusions
SOD from H. pylori can inhibit the production of pro‐inflammatory cytokine during in vivo infection. 相似文献10.
Jiu-Cun Wang Syeling Lai Xinjian Guo Xuefeng Zhang Benoit de Crombrugghe Sonali Sonnylal Frank C Arnett Xiaodong Zhou 《Arthritis research & therapy》2010,12(2):R60
Introduction
SPARC is a matricellular protein, which, along with other extracellular matrix components including collagens, is commonly over-expressed in fibrotic diseases. The purpose of this study was to examine whether inhibition of SPARC can regulate collagen expression in vitro and in vivo, and subsequently attenuate fibrotic stimulation by bleomycin in mouse skin and lungs. 相似文献11.
Background
The mechanisms of abortion induced by bacterial infection are largely unknown. In the present study, we investigated abortion induced by Brucella abortus, a causative agent of brucellosis and facultative intracellular pathogen, in a mouse model. 相似文献12.
Parjam S Zolfaghari Samantha Packer Mervyn Singer Sean P Nair Jon Bennett Cale Street Michael Wilson 《BMC microbiology》2009,9(1):27-8
Background
The widespread problem of antibiotic resistance in pathogens such as Staphylococcus aureus has prompted the search for new antimicrobial approaches. In this study we report for the first time the use of a light-activated antimicrobial agent, methylene blue, to kill an epidemic methicillin-resistant Staphylococcus aureus (EMRSA-16) strain in two mouse wound models. 相似文献13.
Trans-4-hydroxy-l -proline (Hyp) is a useful chiral building block for production of many nutritional supplements and pharmaceuticals. However, it is still challenging for industrial production of Hyp due to heavy environmental pollution and low production efficiency. To establish a green and efficient process for Hyp production, the proline 4-hydroxylase (DsP4H) from Dactylosporangium sp. RH1 was overexpressed and functionally characterized in Escherichia coli BL21(DE3). The recombinant DsP4H with l -proline as a substrate exhibited Km, kcat and kcat/Km values up to 0.80 mM, 0.52 s−1 and 0.65 s−1·mM−1 respectively. Furthermore, DsP4H showed the highest activity at 35°C and pH 6.5 towards l -proline. The highest enzyme activity of 175.6 U mg−1 was achieved by optimizing culture parameters. Under the optimal transformation conditions in a 5-l fermenter, Hyp titre, conversion rate and productivity were up to 99.9 g l−1, 99.9% and 2.77 g l−1 h−1 respectively. This strategy described here provides an efficient method for production of Hyp and thus has a great potential in industrial application. 相似文献
14.
Background
The mammalian protein kinase TLK1 is a homologue of Tousled, a gene involved in flower development in Arabidopsis thaliana. The function of TLK1 is not well known, although knockout of the gene in Drosophila, or expression of a dominant negative mutant in mouse mammary cells causes loss of nuclear divisions and chromosome mis-segregation. TLK1B is a splice variant of TLK1 and it confers radioresistance in a normal mammary mouse cell line possibly due to increased chromatin remodeling capacity, but the mechanism of resistance remains to be fully elucidated. 相似文献15.
16.
Background
Cystic Fibrosis is a pleiotropic disease in humans with primary morbidity and mortality associated with a lung disease phenotype. However, knockout in the mouse of cftr, the gene whose mutant alleles are responsible for cystic fibrosis, has previously failed to produce a readily, quantifiable lung phenotype. 相似文献17.
Rainer Voigt Jelle Atema 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,171(5):673-683
1. | We determined the spectral tuning properties of 47 chemoreceptor cells of the antenna of Homarus americanus to amino acids and other compounds. Tests with 17 single compounds at 10-4 M showed 40 of 47 cells responded best to hydroxyproline, 4 cells to taurine and 3 cells to betaine. Mean tuning breadth (H-metric) doubled with 10 fold increase in concentration. |
2. | In hydroxyproline-best cells the mean threshold for hydroxyproline (Hyp) was found between 10-7 M and 10-8 M. An equimolar mixture of the 17 compounds generated a shallower stimulus-response function with thresholds similar to Hyp function (mixture suppression). Hyp-best cells were relatively narrowly tuned, often with arginine or leucine as second best stimuli. |
3. | Thus, physiologically the second antenna of H. americanus is a major chemoreceptor organ. It is more than any of the 5 chemoreceptor organs studied so far dominated by a single best-cell type (Hyp). Receptor cell composition of antennae resembles that of antennules more than legs or maxillipeds. Hyp-best cells in antennae and lateral antennules have similar tuning spectra. |
4. | Our cell tuning studies argue for independent receptors for all amino acids tested. We conclude that diversity of receptor cell tuning is created by cell-specific blends of receptors. At the organ level, differences in organ tuning result from different blends of receptor cells. |
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19.
Background
Autosomal dominant optic atrophy type 1 (DOA) is the most common form of hereditary optic atrophy in human. We have previously identified the OPA1 gene and shown that it was mutated in patients with DOA. OPA1 is a novel member of the dynamin GTPase family that play a role in the distribution of the mitochondrial network. The Bst (belly spot and tail) mutant mice show atrophy of the optic nerves and previous mapping data raise the possibility that Bst and OPA1 are orthologs. In order to analyse the Bst mouse as a model for DOA, we therefore characterized mouse Opa1 and evaluated it as a candidate for the Bst mutant mouse. 相似文献20.
Jorg Brunner Nina Scheres Nawal B El Idrissi Dong M Deng Marja L Laine Arie J van Winkelhoff Wim Crielaard 《BMC microbiology》2010,10(1):5