Effector enrichment by Candidatus Liberibacter promotes Diaphorina citri feeding via Jasmonic acid pathway suppression.

BACKGROUND: Citrus huanglongbing (HLB) is a devastating disease caused by Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry. In nature, CLas relies primarily on Diaphorina citri Kuwayama as its vector for dissemination. After D. citri ingests CLas-infected citrus, the pathogen infiltrates the insect's body, where it thrives, reproduces, and exerts regulatory control over the growth and metabolism of D. citri. Previous studies have shown that CLas alters the composition of proteins in the saliva of D. citri, but the functions of these proteins remain largely unknown. RESULTS: In this study, we detected two proteins (DcitSGP1 and DcitSGP3) with high expression levels in CLas-infected D. citri. Quantitative PCR and Western blotting analysis showed that the two proteins were highly expressed in the salivary glands and delivered into the host plant during feeding. Silencing the two genes significantly decreased the survival rate for D. citri, reduced phloem nutrition sucking and promoted jasmonic acid (JA) defenses in citrus. By contrast, after overexpressing the two genes in citrus, the expression levels of JA pathway-associated genes decreased. CONCLUSION: Our results suggest that CLas can indirectly suppress the defenses of citrus and support feeding by D. citri via increasing the levels of effectors in the insect's saliva. This discovery facilitates further research into the interaction between insect vectors and pathogens. © 2024 Society of Chemical Industry.

The A391E mutation enhances FGFR3 activation in the absence of ligand.

The A391E mutation in the transmembrane domain of fibroblast growth factor receptor 3 leads to aberrant development of the cranium. It has been hypothesized that the mutant glutamic acid stabilizes the dimeric receptor due to hydrogen bonding and enhances its ligand-independent activation. We previously tested this hypothesis in lipid bilayers and showed that the mutation stabilizes the isolated transmembrane domain dimer by -1.3°kcal/mol. Here we further test the hypothesis, by investigating the effect of the A391E mutation on the activation of full-length fibroblast growth factor receptor 3 in human embryonic kidney 293T cells in the absence of ligand. We find that the mutation enhances the ligand-independent activation propensity of the receptor by -1.7°kcal/mol. This value is consistent with the observed strength of hydrogen bonds in membranes, and supports the above hypothesis.

First Record of Aspergillus fijiensis as an Entomopathogenic Fungus against Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae).

The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is the most widespread and devastating pest species in citrus orchards and is the natural vector of the phloem-limited bacterium that causes Huanglongbing (HLB) disease. Thus, reducing the population of D. citri is an important means to prevent the spread of HLB disease. Due to the long-term use of chemical control, biological control has become the most promising strategy. In this study, a novel highly pathogenic fungal strain was isolated from naturally infected cadavers of adult D. citri. The species was identified as Aspergillus fijiensis using morphological identification and phylogenetic analysis and assigned the strain name GDIZM-1. Tests to detect aflatoxin B1 demonstrated that A. fijiensis GDIZM-1 is a non-aflatoxin B1 producer. The pathogenicity of the strain against D. citri was determined under laboratory and greenhouse conditions. The results of the laboratory study indicated that nymphs from the 1st to 5th instar and adults of D. citri were infected by A. fijiensis GDIZM-1. The mortality of nymphs and adults of D. citri caused by infection with A. fijiensis increased with the concentration of the conidial suspension and exposure time, and the median lethal concentration (LC50) and median lethal time (LT50) values gradually decreased. The mortality of D. citri for all instars was higher than 70%, with high pathogenicity at the 7th day post treatment with 1 × 108 conidia/mL. The results of the greenhouse pathogenicity tests showed that the survival of D. citri adults was 3.33% on the 14th day post-treatment with 1 × 108 conidia/mL, which was significantly lower than that after treatment with the Metarhizium anisopliae GDIZMMa-3 strain and sterile water. The results of the present study revealed that the isolate of A. fijiensis GDIZM-1 was effective against D. citri and it provides a basis for the development of a new microbial pesticide against D. citri after validation of these results in the field.

The physical basis of FGFR3 response to fgf1 and fgf2.

Fibroblast growth factors (fgfs) play important roles in embryonic development and in adult life by controlling cell proliferation, differentiation, and migration. There are 18 known fgfs which activate four fibroblast growth factor receptors (FGFRs), with different isoforms due to alternative splicing. The physical basis behind the specificity of the biological responses mediated by different fgf-FGFR pairs is currently unknown. To gain insight into the specificity of FGFR3c, a membrane receptor which is critical for bone development, we studied, analyzed, and compared the activation of FGFR3c over a wide range of fgf1 and fgf2 concentrations. We found that while the strength of fgf2 binding to FGFR3c is lower than the strength of fgf1 binding, the fgf2-bound dimers exhibit higher phosphorylation of the critical tyrosines in the activation loop. As a result, fgf1 and fgf2 elicit a similar FGFR3c response at low, but not at high, concentrations. The results demonstrate the versatility of FGFR3c response to fgf1 and fgf2 and highlight the complexity in fgf signaling.

Biological characterization and pluripotent identification of ovine amniotic fluid stem cells.

Mesenchymal stem cells derived from amniotic fluid have become one of the most potential stem cell source for cell-based therapy for the reason they can be harvested at low cost and without ethical problems. Here, we obtained amniotic fluid stem cells (AFSCs) from ovine amniotic fluid and studied the expansion capacity, cell markers expression, karyotype, and multilineage differentiation ability. In our work, AFSCs were subcultured to passage 62. The cell markers, CD29, CD44, CD73 and OCT4 which analyzed by RT-PCR were positive; CD44, CD73, CD90, CD105, NANOG, OCT4 analyzed by immunofluorescence and flow cytometry were also positive. The growth curves of different passages were all typically sigmoidal. The different passages cells took on a normal karyotype. In addition, AFSCs were successfully induced to differentiate into adipocytes, osteoblasts and chondrocytes. The results suggested that the AFSCs isolated from ovine maintained normal biological characteristics and their multilineage differentiation potential provides many potential applications in cell-based therapies and tissue engineering.

The biological characteristics of sheep umbilical cord mesenchymal stem cells.

Although mesenchymal stem cells (MSCs) are now regarded as a promising cell resource for tissue repair and regeneration, the optimal source of MSCs has not yet been determined. The objective of this study was to provide a theoretical basis for the clinical application of umbilical cord mesenchymal stem cells (UCMSCs) in the future. Umbilical cord is an easily obtainable tissue resource, which is one reason that it has become a candidate resource for mesenchymal stem cells. In this study, we analyzed the biological characteristics of UCMSCs, such as their multiple differentiation and clone-forming ability, through morphological observation, reverse transcription polymerase chain reaction (RT-PCR), growth curve, positive rate test, and immunophenotype. Umbilical cord MSCs were successfully isolated and passaged to 29 generations. The results from RT-PCR showed that UCMSCs were positive for CD29, CD44, CD73, but negative for CD34. The expression of the stem cell marker nucleostemin and tenocyte-related markers showed similar positive results with CD44, CD73, and CD90. In addition, UCMSCs can be induced to differentiate into osteoblasts, adipocytes, or chondrocytes. Our study showed that UCMSCs not only have the ability to self-renew, but also have the potential to differentiate into multiple lineages. In general, we concluded that UCMSCs are a reliable source for use in cell therapy.

Bien que les cellules souches mésenchymateuses (CSMs) soient maintenant considérées comme une ressource prometteuse de cellules pour la réparation tissulaire et la régénération, la source optimale de CSMs n'a pas encore été déterminée. L'objectif de la présente étude était de fournir une base théorique pour l'application clinique de cellules souches mésenchymateuses de cordon ombilical (CSMCO) dans le futur. Le cordon ombilical est une ressource tissulaire pouvant être obtenue facilement, une des raisons pour laquelle il est devenu un candidat pour les CSMs. Dans cette étude nous avons analysé les caractéristiques biologiques des CSMCO, telles que leur différenciation multiple et la capacité à former des clones, par des observations morphologiques, par réaction d'amplification en chaîne par la polymérase avec la transcriptase réverse (ACP-TR), courbe de croissance, test de ratio positif, et immunophénotype. Les CSMCO ont été isolées avec succès et des passages obtenus jusqu'à la 29e génération. Les résultats d'ACP-TR ont montré que les CSMCO étaient positives pour CD29, CD44, CD73, mais négative pour CD34. L'expression de nucléostémine, un marqueur de cellule souche, et de marqueurs apparentés aux ténocytes ont montré des résultats positifs similaires à ceux de CD44, CD73, et CD90. De plus, les CSMCO peuvent être induites à se différencier en ostéoblastes, adipocytes, ou chondrocytes. Notre étude a démontré que les CSMCO ont non seulement la capacité de s'auto-renouveler, mais ont également le potentiel de se différencier en des lignées multiples. En général, nous avons conclu que les CSMCO sont une source fiable pour utilisation en thérapie cellulaire.(Traduit par Docteur Serge Messier).

In vitro culture and biological properties of broiler adipose-derived stem cells.

In the past 10 years, adipose-derived stem cells (ADSCs) have been applied due to their pluripotency. Experimental tissues have been frequently obtained from mammals, including rabbits, mice and humans, but rarely from broilers, Gallus gallus domesticus. In the present study, ADSCs were obtained from 20-day-old broiler embryos. Primary ADSCs were sub-cultured to passage 37 in vitro. The surface markers of ADSCs, namely CD29, CD31, CD44, CD71 and CD73, were detected by reverse transcription polymerase chain reaction and immunofluorescence assays. The result indicated that CD29, CD44, CD71 and CD73 were expressed on the surface of cells at various passages, but not CD31. The growth curve of cells at the different passages had a typical sigmoidal shape. Furthermore, ADSCs were successfully induced to differentiate into osteoblasts, adipocytes and hepatocyte-like cells. The results denote that the ADSCs isolated from broilers have similar biological properties to those of ADSCs obtained from other animals. The present study provided a theoretical and experimental foundation for the use of poultry as a source of stem cells, and laid a foundation for adipose tissue engineering and strategies in regenerative medicine.

Multiple consequences of a single amino acid pathogenic RTK mutation: the A391E mutation in FGFR3.

The A391E mutation in fibroblast growth factor receptor 3 (FGFR3) is the genetic cause for Crouzon syndrome with Acanthosis Nigricans. Here we investigate the effect of this mutation on FGFR3 activation in HEK 293 T cells over a wide range of fibroblast growth factor 1 concentrations using a physical-chemical approach that deconvolutes the effects of the mutation on dimerization, ligand binding, and efficiency of phosphorylation. It is believed that the mutation increases FGFR3 dimerization, and our results verify this. However, our results also demonstrate that the increase in dimerization is not the sole effect of the mutation, as the mutation also facilitates the phosphorylation of critical tyrosines in the activation loop of FGFR3. The activation of mutant FGFR3 is substantially increased due to a combination of these two effects. The low expression of the mutant, however, attenuates its signaling and may explain the mild phenotype in Crouzon syndrome with Acanthosis Nigricans. The results presented here provide new knowledge about the physical basis behind growth disorders and highlight the fact that a single RTK mutation may affect multiple steps in RTK activation.