The establishment of the rhizobium-legume nitrogen-fixing symbiosis relies on the interchange of molecular signals between the two symbionts. We have previously studied by RNA-seq the effect of the ...symbiotic regulators NodD1, SyrM, and TtsI on the expression of the symbiotic genes (the
regulon) of
HH103 upon treatment with the isoflavone genistein. In this work we have further investigated this regulatory network by incorporating new RNA-seq data of HH103 mutants in two other regulatory genes,
and
. Both genes code for global regulators with a predominant repressor effect on the
regulon, although NodD2 acts as an activator of a small number of HH103 symbiotic genes.
By combining RNA-seq data, qPCR experiments, and b-galactosidase assays of HH103 mutants harbouring a
gene inserted into a regulatory gene, we have analysed the regulatory relations between the
,
,
,
, and
genes, confirming previous data and discovering previously unknown relations.
Previously we showed that HH103 mutants in the
,
,
, or
genes gain effective nodulation with
, a model legume, although with different symbiotic performances. Here we show that the combinations of mutations in these genes led, in most cases, to a decrease in symbiotic effectiveness, although all of them retained the ability to induce the formation of nitrogen-fixing nodules. In fact, the
,
, and
single and double mutants share a set of Nod factors, either overproduced by them or not generated by the wild-type strain, that might be responsible for gaining effective nodulation with
.
Rhizobial NodD proteins and appropriate flavonoids induce rhizobial nodulation gene expression. In this study, we show that the
gene of
HH103, but not the
gene, can restore the nodulation capacity of ...a double
/
mutant of
CIAT 899 in bean plants (
).
HH103 only induces pseudonodules in beans. We have also studied whether the mutation of different symbiotic regulatory genes may affect the symbiotic interaction of HH103 with beans:
(the positive regulator of the symbiotic type 3 protein secretion system), and
,
and
(all of them controlling the level of Nod factor production). Inactivation of either
,
or
, but not that of
, affected positively the symbiotic behavior of HH103 with beans, leading to the formation of colonized nodules. Acetylene reduction assays showed certain levels of nitrogenase activity that were higher in the case of the
and
mutants. Similar results have been previously obtained by our group with the model legume
. Hence, the results obtained in the present work confirm that repression of Nod factor production, provided by either NodD2, NolR or SyrM, prevents HH103 to effectively nodulate several putative host plants.
Simultaneous quantification of transcripts of the whole bacterial genome allows the analysis of the global transcriptional response under changing conditions. RNA-seq and microarrays are the most ...used techniques to measure these transcriptomic changes, and both complement each other in transcriptome profiling. In this review, we exhaustively compiled the symbiosis-related transcriptomic reports (microarrays and RNA sequencing) carried out hitherto in rhizobia. This review is specially focused on transcriptomic changes that takes place when five rhizobial species,
(=
) USDA 110,
biovar
3841,
CIAT 899,
(=
)
1021 and
HH103, recognize inducing flavonoids, plant-exuded phenolic compounds that activate the biosynthesis and export of Nod factors (NF) in all analysed rhizobia. Interestingly, our global transcriptomic comparison also indicates that each rhizobial species possesses its own arsenal of molecular weapons accompanying the set of NF in order to establish a successful interaction with host legumes.
Summary
Sinorhizobium fredii HH103 RifR, a broad‐host‐range rhizobial strain, forms ineffective nodules with Lotus japonicus but induces nitrogen‐fixing nodules in Lotus burttii roots that are ...infected by intercellular entry. Here we show that HH103 RifR nolR or nodD2 mutants gain the ability to induce infection thread formation and to form nitrogen‐fixing nodules in L. japonicus Gifu. Microscopy studies showed that the mode of infection of L. burttii roots by the nodD2 and nolR mutants switched from intercellular entry to infection threads (ITs). In the presence of the isoflavone genistein, both mutants overproduced Nod‐factors. Transcriptomic analyses showed that, in the presence of Lotus japonicus Gifu root exudates, genes related to Nod factors production were overexpressed in both mutants in comparison to HH103 RifR. Complementation of the nodD2 and nolR mutants provoked a decrease in Nod‐factor production, the incapacity to form nitrogen‐fixing nodules with L. japonicus Gifu and restored the intercellular way of infection in L. burttii. Thus, the capacity of S. fredii HH103 RifR nodD2 and nolR mutants to infect L. burttii and L. japonicus Gifu by ITs and fix nitrogen L. japonicus Gifu might be correlated with Nod‐factor overproduction, although other bacterial symbiotic signals could also be involved.
Escherichia coli (E. coli) may be harmful to humans. Hence, a rapid, low cost, and easy detection method is needed, and optical biosensors are an excellent option. Here a new platform based upon ...silicon carbide and titanium (SiC-Ti) was used to determine enteropathogenic E. coli by Fourier transform infrared (FTIR) spectroscopy. Self-assembly monolayer (SAM) approach was used to modify the platform. Antibody anti-E. coli flagella were obtained and utilized as the biological recognition element. Three concentrations of bacteria (10, 100, and 1000 CFU/mL) were determined. The detection region was from 1330 to 1480 cm
−1
, where characteristic bands associated with E. coli were determined. An increase in the absorption intensity was observed with the bacteria concentration, demonstrating suitability for quantitative analysis.
The whole-body iodine-131 scintigraphy is an imaging technique in monitoring patients with a history of thyroid cancer. Although the rate of false positives is negligible, it is not nonexistent. We ...report the case of an intervened and treated patient for thyroid cancer with good clinical and biochemical response. Scintigraphic findings were consistent with unsuspected bone metastasis. Fused SPECT/CT data allowed accurate diagnosis of giant diaphragmatic hernia associated with intrathoracic stomach, a very rare pathology that can lead to false positive results.
Salmonella is one of the main microorganisms that causes food-borne illnesses worldwide, although there are standard procedures to determine its presence or absence in food samples. However, these ...methodologies are time consuming and cumbersome, so the development of devices that rapidly and accurately determine bacteria is necessary. Various materials have been used to construct these devices. Hydrogenated amorphous silicon carbide (a-SiC:H) is one of the least studied. Therefore, in the present work, self-assembled monolayers were applied on a-SiC:H thin films to determine Salmonella Typhimurium ATCC 14028 by Fourier transform infrared spectroscopy. The detection of this microorganism was performed between 1060 and 960 cm
−1
corresponding to carbohydrate and phosphate groups of the bacteria. The lowest detected concentration was 10 CFU/mL. This work confirms the utility of a-SiC:H to reliably and rapidly determine Salmonella.
•The a-SiC:H platform as an alternative for development biosensors.•Antibodies immobilized by non-specific physical adsorption have better bioactivity than by covalent attachment.•Wrong orientation ...and the excess of the immobilized antibodies can impair the capture of the antigen in the development of immunosensors.
In this work, we evaluate the performance of two biofunctionalization processes on silicon and hydrogenated amorphous silicon carbide (a-SiC:H). The biofunctionalization processes were designed to immobilize antibodies via non-specific physical adsorption or covalent attachment. The impact of the two surface types (crystalline and amorphous) on the resulting immunosensing layer is discussed in terms of the possible orientation, stability, and bioactivity of the immobilized antibodies. To evaluate the formation of active groups on the surface before and after the immobilization process, we used Fourier-transform infrared (FTIR) spectroscopy. On the other hand, to visualize the topography changes on the different surfaces with immobilized antibodies, we used atomic force microscopy (AFM). ELISA assay was conducted to obtain a quantitative parameter associated with the density of immobilized antibodies on the platforms. The results showed that the antibodies were immobilized on both platforms by any of the two immobilization mechanisms. The antigen capture did not show a direct relationship with the antibody estimation made by ELISA. According to the results, the a-SiC:H platforms by covalent attachment achieved the highest density of immobilized antibodies compared to silicon. However, its performance in the antigen detection assay was lower compared to silicon platforms. We concluded that the performance of the silicon platform was better in terms of its biofunctionalization and antigen detection. The orientation and structural integrity of the antibodies on the platforms was crucial to its performance on antigen detection.
Endometriosis is linked to altered cell proliferation and stem cell markers c-kit/stem cell factor (SCF) in ectopic endometrium. Our aim was to investigate whether c-kit/SCF also plays a role in ...eutopic endometrium.
Eutopic endometrium obtained from 35 women with endometriosis and 25 fertile eumenorrheic women was analyzed for in situ expression of SCF/c-kit, Ki67, RAC-alpha serine/threonine-protein kinase (Akt), phosphorylated RAC-alpha serine/threonin-protein kinase (pAkt), Glycogen synthase kinase 3 beta (GSK3β), and phosphorylated glycogen synthase kinase 3 beta (pGSK3β), throughout the menstrual cycle.
Expression of Ki67 and SCF was higher in endometriosis than in control tissue (P < .05) and greater in secretory rather than proliferative (P < .01) endometrium in endometriosis. Expression of c-kit was also higher in endometriosis although similar in both phases. Expression of Akt and GSK3β was identical in all samples and cycle phases, whereas pAkt and pGSK3β, opposed to control tissue, remained overexpressed in the secretory phase in endometriosis.
Unceasing cell proliferation in the secretory phase of eutopic endometriosis is linked to deregulation of c-kit/SCF-associated signaling pathways.
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