Nodule Cells Research Articles

Single cell‐type transcriptome profiling reveals genes that promote nitrogen fixation in the infected and uninfected cells of legume nodules

Single cell‐type transcriptome profiling reveals genes that promote nitrogen fixation in the infected and uninfected cells of legume nodules

SHORT-ROOT paralogs mediate feedforward regulation of D-type cyclin to promote nodule formation in soybean

Nitrogen fixation in soybean takes place in root nodules that arise from de novo cell divisions in the root cortex. Although several early nodulin genes have been identified, the mechanism behind the stimulation of cortical cell division during nodulation has not been fully resolved. Here we provide evidence that two paralogs of soybean SHORT-ROOT (GmSHR) play vital roles in soybean nodulation. Expression of GmSHR4 and GmSHR5 (GmSHR4/5) is induced in cortical cells at the beginning of nodulation, when the first cell divisions occur. The expression level of GmSHR4/5 is positively associated with cortical cell division and nodulation. Knockdown of GmSHR5 inhibits cell division in outer cortical layers during nodulation. Knockdown of both paralogs disrupts the cell division throughout the cortex, resulting in poorly organized nodule primordia with delayed vascular tissue formation. GmSHR4/5 function by enhancing cytokinin signaling and activating early nodulin genes. Interestingly, D-type cyclins act downstream of GmSHR4/5, and GmSHR4/5 form a feedforward loop regulating D-type cyclins. Overexpression of D-type cyclins in soybean roots also enhanced nodulation. Collectively, we conclude that the GmSHR4/5-mediated pathway represents a vital module that triggers cytokinin signaling and activates D-type cyclins during nodulation in soybean.

Pediatric Gastrointestinal Histopathology in Patients With Tetratricopeptide Repeat Domain 7A (TTC7A) Germline Mutations: A Rare Condition Leading to Multiple Intestinal Atresias, Severe Combined Immunodeficiency, and Congenital Enteropathy.

Mutations in the tetratricopeptide repeat domain 7A (TTC7A) gene are a rare cause of congenital enteropathy that can result in significant morbidity. TTC7A deficiency leads to disruption of the intestinal epithelium. The histopathology of this condition has been partly described in case reports and clinical studies. This manuscript describes an in-depth investigation of the pediatric gastrointestinal pathology of the largest histologically examined cohort with confirmed TTC7A mutations reported to date and, for the first time, compared the findings to age-matched and sex-matched control patients with intestinal atresia not thought to be associated with TTC7A mutations. Hematoxylin and eosin-stained slides of endoscopically obtained mucosal biopsies and surgical resection specimens from 7 patients with known TTC7A mutations were examined retrospectively. The microscopic findings were found to be on a spectrum from atresia-predominant to those with predominantly epithelial abnormalities. Several unique histopathologic characteristics were observed when compared with controls. These included neutrophilic colitis and prominent lamina propria eosinophilia throughout the gastrointestinal tract. Striking architectural abnormalities of the epithelium were observed in 4 of the 7 patients. The 5 patients with intestinal atresia demonstrated hypertrophy and disorganization of the colonic muscularis mucosae accompanied by bland spindle cell nodules within the intestinal wall. The components of the latter were further elucidated using immunohistochemistry, and we subsequently hypothesize that they represent obliterated mucosa with remnants of the muscularis mucosae. Finally, atrophic gastritis was noted in 4 patients. In conclusion, the unique histopathologic characteristics of TTC7A mutation-associated enteropathy described herein more fully describe this novel disease entity in infants who present with congenital enteropathy or enterocolitis.

18F]FDG-PET/CT to prevent futile surgery in indeterminate thyroid nodules: a blinded, randomised controlled multicentre trial

PurposeTo assess the impact of an [18F]FDG-PET/CT-driven diagnostic workup to rule out malignancy, avoid futile diagnostic surgeries, and improve patient outcomes in thyroid nodules with indeterminate cytology.MethodsIn this double-blinded, randomised controlled multicentre trial, 132 adult euthyroid patients with scheduled diagnostic surgery for a Bethesda III or IV thyroid nodule underwent [18F]FDG-PET/CT and were randomised to an [18F]FDG-PET/CT-driven or diagnostic surgery group. In the [18F]FDG-PET/CT-driven group, management was based on the [18F]FDG-PET/CT result: when the index nodule was visually [18F]FDG-positive, diagnostic surgery was advised; when [18F]FDG-negative, active surveillance was recommended. The nodule was presumed benign when it remained unchanged on ultrasound surveillance. In the diagnostic surgery group, all patients were advised to proceed to the scheduled surgery, according to current guidelines. The primary outcome was the fraction of unbeneficial patient management in one year, i.e., diagnostic surgery for benign nodules and active surveillance for malignant/borderline nodules. Intention-to-treat analysis was performed. Subgroup analyses were performed for non-Hürthle cell and Hürthle cell nodules.ResultsPatient management was unbeneficial in 42% (38/91 [95% confidence interval [CI], 32–53%]) of patients in the [18F]FDG-PET/CT-driven group, as compared to 83% (34/41 [95% CI, 68–93%]) in the diagnostic surgery group (p < 0.001). [18F]FDG-PET/CT-driven management avoided 40% (25/63 [95% CI, 28–53%]) diagnostic surgeries for benign nodules: 48% (23/48 [95% CI, 33–63%]) in non-Hürthle cell and 13% (2/15 [95% CI, 2–40%]) in Hürthle cell nodules (p = 0.02). No malignant or borderline tumours were observed in patients under surveillance. Sensitivity, specificity, negative and positive predictive value, and benign call rate (95% CI) of [18F]FDG-PET/CT were 94.1% (80.3–99.3%), 39.8% (30.0–50.2%), 95.1% (83.5–99.4%), 35.2% (25.4–45.9%), and 31.1% (23.3–39.7%), respectively.ConclusionAn [18F]FDG-PET/CT-driven diagnostic workup of indeterminate thyroid nodules leads to practice changing management, accurately and oncologically safely reducing futile surgeries by 40%. For optimal therapeutic yield, application should be limited to non-Hürthle cell nodules.Trial registration numberThis trial is registered with ClinicalTrials.gov: NCT02208544 (5 August 2014), https://clinicaltrials.gov/ct2/show/NCT02208544.

Antitumor Immunity from Abdominal Flap-Embedded Therapeutic Cancer Vaccine.

BackgroundAbdominal flaps are routinely performed in clinic after primary mastectomy of breast cancer. However, cancer patients can still develop cancer recurrence and metastasis after surgery. In this study, we evaluated the feasibility of concurrent abdominal flap reconstruction and vaccine inoculation in the tissue for prevention and treatment of HER2-positive breast cancer.MethodsA murine model of metastatic HER2-positive breast cancer was generated by inoculating HER2-expressing TUBO tumor cells into both the mammary gland fat pad and left ventricle. Mammary gland fat pad with primary tumor was resected by mastectomy, and superficial inferior epigastric (SIE) vessel-based abdominal flap was performed for abdominal reconstruction. During the surgery, mice also received a single intra-flap treatment of a microparticulate-based cancer vaccine. Popliteal (Pop) and inguinal (Ing) lymph nodes (LN) were collected at different time points after vaccination, and activation of dendritic cells and T lymphocytes was evaluated with flow cytometry. ELISpot was also performed to measure HER2-specific T cells in splenocytes. In addition, infiltration of CD3+ T cells in brain metastatic nodules was analyzed with immunohistochemistry.ResultsFlow cytometry detected increased number of activated dendritic cells in lymph nodes in mice treated with cancer vaccine. ELISpot revealed abundant IFN-γ-expressing T cells in the spleen. Mice treated with abdominal flap-embedded cancer vaccine extended median survival by 9 days over the control group (p<0.05).ConclusionAbdominal flap-embedded cancer vaccine effectively stimulated systemic immune response and inhibited tumor progression in a murine model of HER2-positive breast cancer.

Invasive papillary carcinoma of the breast – A rare case report

Invasive papillary carcinoma (IPC) of the breast is a rare entity, comprising approximately <1%–2% of all breast cancers. It is most commonly seen in postmenopausal females and rarely seen in males. IPC is arising from the dilated duct or large duct. They are low-grade tumors microscopically consisting of well-circumscribed solid nodules of the neoplastic cells separated by fibrovascular cores. It has excellent prognosis, so exact diagnosis is necessary. We report a case of a 68-year-old postmenopausal female, who came with complaints of a lump in the left breast for the past 2 months, modified radical mastectomy was done, and the specimen was sent for histopathological examination. Immunohistochemistry was done estrogen receptor and progesterone receptor positive with human epidermal growth factor receptor 2 negative. The case is presented due to its rarity.

A bioactive poly(ether-ether-ketone) nanocomposite scaffold regulates osteoblast/osteoclast activity for the regeneration of osteoporotic bone.

Due to the lower regeneration capacity of the osteoporotic bone, the treatment of osteoporotic defects is extremely challenging in clinics. In this study, strontium-doped bioactive glass nanoparticles loaded with sodium alendronate (ALN), namely A-SrBG, were incorporated into the poly(ether-ether-ketone) matrix to fabricate a bioactive composite scaffold (ASP), which was expected to both inhibit bone resorption and promote bone regeneration. The results showed that such a composite scaffold with interconnected macropores (200-400 μm) could release Ca2+, Sr2+, and ALN in vitro. The proliferation, alkaline phosphatase (ALP) activity, expression of osteogenesis-related genes, and formation of calcified nodules of rat bone marrow stromal cells (rBMSCs) were clearly evidenced, and the reduction in the proliferation, tartrate-resistant acid phosphatase (TRAP) activity, cell fusion, and expression of osteoclastogenesis-related genes of osteoclasts was observed as well. In the presence of the ASP scaffold, enhanced osteogenesis along with inhibiting osteoclastogenesis was observed by modulating the osteoprotegerin (OPG)/receptor activator for nuclear factor κB ligand (RANKL) ratio. The efficacy of the composite scaffold in the regeneration of osteoporotic critical-sized cranial defect in a rat model was evaluated. Therefore, the bioactive composite scaffold with excellent biocompatibility and osteogenic potential could be a promising material for the repair of osteoporotic bone defects.

Sertoli Cell Nodule with Histomorphological and Immunohistochemical Features and its Differential Diagnosis: A Case Report

Sertoli Cell Nodule with Histomorphological and Immunohistochemical Features and its Differential Diagnosis: A Case Report

Amino Acid Polymorphisms in the VHIID Conserved Motif of Nodulation Signaling Pathways 2 Distinctly Modulate Symbiotic Signaling and Nodule Morphogenesis in Medicago truncatula.

Legumes establish an endosymbiotic association with nitrogen-fixing soil bacteria. Following the mutual recognition of the symbiotic partner, the infection process is controlled by the induction of the signaling pathway and subsequent activation of symbiosis-related host genes. One of the protein complexes regulating nitrogen-fixing root nodule symbiosis is formed by GRAS domain regulatory proteins Nodulation Signaling Pathways 1 and 2 (NSP1 and NSP2) that control the expression of several early nodulation genes. Here, we report on a novel point mutant allele (nsp2-6) affecting the function of the NSP2 gene and compared the mutant with the formerly identified nsp2-3 mutant. Both mutants carry a single amino acid substitution in the VHIID motif of the NSP2 protein. We found that the two mutant alleles show dissimilar root hair response to bacterial infection. Although the nsp2-3 mutant developed aberrant infection threads, rhizobia were able to colonize nodule cells in this mutant. The encoded NSP2 proteins of the nsp2-3 and the novel nsp2 mutants interact with NSP1 diversely and, as a consequence, the activation of early nodulin genes and nodule organogenesis are arrested in the new nsp2 allele. The novel mutant with amino acid substitution D244H in NSP2 shows similar defects in symbiotic responses as a formerly identified nsp2-2 mutant carrying a deletion in the NSP2 gene. Additionally, we found that rhizobial strains induce delayed nodule formation on the roots of the ns2-3 weak allele. Our study highlights the importance of a conserved Asp residue in the VHIID motif of NSP2 that is required for the formation of a functional NSP1-NSP2 signaling module. Furthermore, our results imply the involvement of NSP2 during differentiation of symbiotic nodule cells.

Exploring apoplast reorganization in the nodules of Lotus corniculatus L. growing on old Zn–Pb calamine wastes

Nodulation and symbiotic nitrogen fixation are important factors that determine legume growth. A pot experiment was carried out to determine the effects of Zn–Pb contamination on nodule apoplast (cell walls and intercellular spaces) of bird's foot trefoil (Lotus corniculatus L.) that spontaneously colonized old calamine wastes. The plants were grown in pots filled with sterile calamine substrate (M, metal treated) or expanded clay (NM, untreated) and inoculated with calamine-derived Lotus-nodulating Bradyrhizobium liaoningense. Apoplast reorganization in the nodules was examined using specific dyes for cellulose, pectin and lignin detection, and immuno-histochemical techniques based on monoclonal antibodies against xyloglucan (Lm25), pectins (Jim5 and Jim7), and structural proteins (arabinogalactan protein - Lm14 and extensin - Jim12). Microscopic analysis of metal-treated nodules revealed changes in the apoplast structure and composition of nodule cortex tissues and infected cells. Wall thickening was accompanied by intensified deposition of cellulose, xyloglucan, esterified pectin, arabinogalactan protein and extensin. The metal presence redirected also lignin and suberin deposition in the walls of the nodule cortex tissues.Our results showed reorganization of the apoplast of cortex tissues and infected cells of Lotus nodules under Zn–Pb presence. These changes in the apoplast structure and composition may have created actual barriers for the toxic ions. For this reason, they can be regarded as an element of legume defense strategy against metal stress that enables effective functioning of L. corniculatus-rhizobia symbiosis on Zn–Pb polluted calamine tailings.

Malate Transport and Metabolism in Nitrogen-Fixing Legume Nodules.

Legumes form a symbiosis with rhizobia, a soil bacterium that allows them to access atmospheric nitrogen and deliver it to the plant for growth. Biological nitrogen fixation occurs in specialized organs, termed nodules, that develop on the legume root system and house nitrogen-fixing rhizobial bacteroids in organelle-like structures termed symbiosomes. The process is highly energetic and there is a large demand for carbon by the bacteroids. This carbon is supplied to the nodule as sucrose, which is broken down in nodule cells to organic acids, principally malate, that can then be assimilated by bacteroids. Sucrose may move through apoplastic and/or symplastic routes to the uninfected cells of the nodule or be directly metabolised at the site of import within the vascular parenchyma cells. Malate must be transported to the infected cells and then across the symbiosome membrane, where it is taken up by bacteroids through a well-characterized dct system. The dicarboxylate transporters on the infected cell and symbiosome membranes have been functionally characterized but remain unidentified. Proteomic and transcriptomic studies have revealed numerous candidates, but more work is required to characterize their function and localise the proteins in planta. GABA, which is present at high concentrations in nodules, may play a regulatory role, but this remains to be explored.

Malignancy risk in indeterminate thyroid nodules with Hürthle cells: role of autoimmune thyroiditis.

Hürthle cells are modified follicular thyroid cells, whose development and proliferation have been related to different stimuli inducing cellular stress. Most thyroid aspirates containing Hürthle cells are classified as indeterminate, although the specific risk of malignancy for this subtype of atypia remains unclear. The aim of our study was to assess if the presence of Hürthle cells in indeterminate thyroid nodules correlates with the risk of malignancy. We further evaluated if this risk can be modified by the presence of an underlying Hashimoto's thyroiditis. We retrospectively analyzed all indeterminate thyroid nodules that were surgically treated at our institution between January 2010 and March 2019. For each nodule, we inferred the presence of Hürthle cells in the cytological report. Cytological findings were then correlated with histological reports. 354 indeterminate thyroid nodules were included in the study. The rate of malignancy resulted significantly lower in nodules exhibiting Hürthle cells compared to those negative for this cellular pattern (11.4% vs 22.5%, p = 0.01). Although there was no difference in the rate of malignancy in the whole population according to the presence or absence of Hashimoto's thyroiditis (21.5 vs 18.5%, p = 0.63), the significantly lower prevalence of malignant lesions in nodules with Hürthle cells was confirmed only in the presence of a histologically documented Hashimoto's thyroiditis (6.2% vs 32%, p = 0.005). The finding of Hürthle cells in indeterminate thyroid nodules is associated with a low risk of malignancy in patients with an underlying Hashimoto's thyroiditis. The clinical management of these lesions may therefore be more conservative.

Artificial Intelligence-Assisted Mapping of Proliferation Centers in Chronic Lymphocytic Leukemia/ Small Lymphocytic Lymphoma Identifies Patterns That Reliably Distinguish Accelerated Phase and Large Cell Transformation

BackgroundChronic lymphocytic leukemia (CLL) involving tissues is characterized by sheets of small lymphocytes and vague nodules of larger cells, known as proliferation centers (PCs). CLL can undergo progression to accelerated CLL (aCLL) or further progress to diffuse large B-cell lymphoma, also known as Richter transformation (RT). Distinguishing CLL with many PCs from aCLL or RT can be challenging, particularly in small needle-biopsy specimens. In this study, we sought to design an artificial intelligence (AI)-based tool to automate and enhance the delineation of PCs and provide an objective approach to CLL/SLL acceleration/transformation.Material & MethodsWe manually annotated 25, 28 and 21 regions of interest (ROIs) encompassing small round PCs and confluent/ expanded PCs of 10 CLL, 12 aCLL, and 8 RT digitized hematoxylin & eosin stained slides, respectively (Figure A1). We analyzed the ROIs with both length and width larger than 2,000 pixels and set the tile length and stride as 1,000 and 100 pixels, respectively (Figure A1), and were able to extract sufficient tiles from each ROI (Figure A2). To recreate PCs, after performing nuclear segmentation via convolutional neural network and quality control, we quantified the nuclear size/intensity of cells occupying each tile (Figure A3). Nuclear size varied from 8 to 108 square micrometers, and nuclear mean intensity varied from 0 to 255. We normalized both the values of nuclear size and mean intensity to 0.0 and 1.0, by subtracting the minimum value and dividing it by the value range length. Nuclear size and mean intensity were represented as S(celli) and Imean(celli), respectively. We estimated the heat value of one tile integrating nuclear and mean intensity using the equationin Figure A2.ResultsWe generated heatmaps based on the heat values per tile inside each ROI from the 3 disease entities (CLL, aCLL and RT), as illustrated in Figures B1-4. Areas with high heat values (in the yellow spectrum) correspond to tiles harboring cells with increased nuclear size and mean intensity (PCs in CLL cases and expanded/ confluent PCs in aCLL and RT cases). In contrast, areas with low heat values (in the blue spectrum) correspond to tiles with decreased nuclear size and mean intensity (small neoplastic lymphocytes surrounding PCs) (Figure B4). We then generated a heat value histogram per tile for each ROI (Figure B5). Based on these results, the two optimal thresholds isolated to obtain the highest separation value among the three disease entities based on the optimal F-score were: 0.228, below which the case was most likely to be CLL, and 0.288, above which the case was most likely to be RT. Cases with heat values ranging between 0.228 and 0.288 were most likely aCLL cases. We then plotted the mean heat value frequencies of the 3 entities: There was a significant difference in the ranges of mean heat value frequencies for CLL, aCLL, and RT, which were 0.168 to 0.233, 0.212 to 0.307, and 0.261 to 0.353, respectively (Figure C). The accuracy and area under the curve diagnostic predictive values using data from nuclear size alone were 0.658 (+/-0.115) and 0.771 (+/-0.096), respectively; and using mean nuclear intensity, 0.679 (+/-0.094) and 0.841 (+/-0.052), respectively; with a noticeable increase using heat value frequencies (integrating the nuclear size and mean nuclear intensity) reaching 0.813 (+/-0.0630) and 0.885 (+/-0.109), respectively.ConclusionWe describe a novel AI-based heatmap technique to objectively assess the extent of PCs in CLL, based on the integrative analysis of cell nuclear size and mean nuclear intensity. We suggest that an ROI mean heat value less than 0.228 is predictive of CLL, and more than 0.288 is predictive of RT. aCLL cases demonstrate a mean heat value ranging from 0.228 to 0.288. Using the mean heat value of all cases, we were able to reliably separate the three entities in question with robust diagnostic predictive values. [Display omitted] DisclosuresKhoury: Stemline Therapeutics: Research Funding; Kiromic: Research Funding; Angle: Research Funding.

S2611 When FNH Is Not FNH: The Value of the Multidisciplinary Conference for Management of Hepatic Masses

Introduction: While hepatocellular carcinoma (HCC) can arise spontaneously, the majority of cases are observed in patients with cirrhosis or chronic hepatitis infection. Hepatocellular adenoma is also an important cause of liver mass, but is often found in women and associated with exposure to estrogens. Adenomas can be seen in males, especially those with history of anabolic androgen use. Focal nodular hyperplasia (FNH) is another benign cause of liver mass usually seen in females. We report a case of an undifferentiated liver mass in a healthy male patient that was originally thought to be FNH but turned out to be a more serious condition. Case Description/Methods: An asymptomatic 36-year-old man with unremarkable medical history presented with a liver mass after routine blood work revealed an elevated alkaline phosphatase. Risk factors for liver disease included obesity and hyperlipidemia. Imaging demonstrated a mass in the right hepatic lobe (8.1 x 7.1 x 9.0 cm), with arterial hyperenhancement, followed by isointensity to the liver after the arterial phase. The surrounding parenchyma appeared normal. He had no exposure to hepatitis B or C and his chronic liver disease evaluation was negative. Alpha fetoprotein was normal. Given these findings, the lesion was initially deemed most consistent with FNH. Multidisciplinary review instead favored adenoma or HCC, due to male gender, lesion size, T2 hyperintensity relative to liver, and central areas of high signal intensity that did not fill like a classic central scar. The patient subsequently underwent right hepatectomy. Surgical pathology revealed a well-differentiated hepatocellular neoplasm without invasion of the surrounding vasculature. The lesion had a prominent capsule and consisted of sheets and nodules of well-differentiated hepatic cells. The remainder of the liver parenchyma showed mild steatosis without inflammation or fibrosis. Pathology was reviewed at multiple institutions, with results favoring a well-differentiated HCC or atypical adenoma. Unfortunately, it was difficult to determine whether this mass was benign or malignant. Discussion: In this case, presentation at a multidisciplinary conference was lifesaving. Given that adenomas of this size carry high risk for malignant transformation or rupture, and large HCC often metastasize and can be terminal, surgery was indicated regardless of diagnosis. However, FNH can typically be observed. The patient now follows with Oncology and Hepatology for surveillance imaging and labs every 3 months.Figure 1.: A. Contrast-enhanced MRI demonstrates a large (8.1 x 7.1 x 9.0 cm) right hepatic lobe mass with heterogeneous hyperenhancement in the arterial phase. B. Gross pathology of 9.7cm tumor in right hepatic lobe. C. High magnification of the tumor (H&E) showing unpaired arteries without abnormal thickening of hepatocellular plates.

High-frequency and activation of CD4+CD25+ T cells maintain persistent immunotolerance induced by congenital ALV-J infection

Congenital avian leukosis virus subgroup J (ALV-J) infection can induce persistent immunotolerance in chicken, however, the underlying mechanism remains unclear. Here, we demonstrate that congenital ALV-J infection induces the production of high-frequency and activated CD4+CD25+ Tregs that maintain persistent immunotolerance. A model of congenital infection by ALV-J was established in fertilized eggs, and hatched chicks showed persistent immunotolerance characterized by persistent viremia, immune organ dysplasia, severe imbalance of the ratio of CD4+/CD8+ T cells in blood and immune organs, and significant decrease in CD3+ T cells and Bu-1+ B cells in the spleen. Concurrently, the mRNA levels of IL-2, IL-10, and IFN-γ showed significant fluctuations in immune organs. Moreover, the frequency of CD4+CD25+ Tregs in blood and immune organs significantly increased, and the frequency of CD4+CD25+ Tregs was positively correlated with changes in ALV-J load in immune organs. Interestingly, CD4+CD25+ Tregs increased in the marginal zone of splenic nodules in ALV-J-infected chickens and dispersed to the germinal center. In addition, the proliferation and activation of B cells in splenic nodules was inhibited, and the number of IgM+ and IgG+ cells in the marginal zone significantly decreased. We further found that the mRNA levels of TGF- β and CTLA-4 in CD4+CD25+ Tregs of ALV-J-infected chickens significantly increased. Together, high-frequency and activated CD4+CD25+ Tregs inhibited B cells functions by expressing the inhibitory cytokine TGF-β and inhibitory surface receptor CTLA-4, thereby maintaining persistent immunotolerance in congenital ALV-J-infected chickens.

The Mesorhizobium huakuii transcriptional regulator AbiEi plays a critical role in nodulation and is important for bacterial stress response

BackgroundBacterial abortive infection (Abi) systems are type IV toxin–antitoxin (TA) system, which could elicit programmed cell death and constitute a native survival strategy of pathogenic bacteria under various stress conditions. However, no rhizobial AbiE family TA system has been reported so far. Here, a M. huakuii AbiE TA system was identified and characterized.ResultsA mutation in M. huakuii abiEi gene, encoding an adjacent GntR-type transcriptional regulator, was generated by homologous recombination. The abiEi mutant strain grew less well in rich TY medium, and displayed increased antioxidative capacity and enhanced gentamicin resistance, indicating the abiEi operon was negatively regulated by the antitoxin AbiEi in response to the oxidative stress and a particular antibiotic. The mRNA expression of abiEi gene was significantly up-regulated during Astragalus sinicus nodule development. The abiEi mutant was severely impaired in its competitive ability in rhizosphere colonization, and was defective in nodulation with 97% reduction in nitrogen-fixing capacity. The mutant infected nodule cells contained vacuolation and a small number of abnormal bacteroids with senescence character. RNA-seq experiment revealed it had 5 up-regulated and 111 down-regulated genes relative to wild type. Of these down-regulated genes, 21 are related to symbiosis nitrogen fixation and nitrogen mechanism, 16 are involved in the electron transport chain and antioxidant responses, and 12 belong to type VI secretion system (T6SS).ConclusionsM. huakuii AbiEi behaves as a key transcriptional regulator mediating root nodule symbiosis.

Soil moisture, N, P, and forest cover effects on N fixation in alders in the southern boreal forest

AbstractOutside of tropical and arid regions, plant productivity is limited by the availability of soil N. Ironically, these are the regions where N‐fixing plants are restricted to early successional habitats. The energy cost of N fixation has been used to explain the paucity of N‐fixing plants in late‐successional ecosystems, and models predict reduced light and increased soil N availability will reduce N‐fixing plant success. The lack of success of N‐fixing plants has also been explained by their greater need for some elements, especially phosphorus. We examined the effect of N and P fertilizer over four years on N fixation in Alnus alnobetula spp. crispa in a mature Pinus banksiana forest in the southern boreal forest, and an adjacent site where wildfire had removed the tree canopy. We also monitored N fixation throughout two growing seasons examined the effect of artificial shading on photosynthesis. The addition of N or P fertilizer resulted in a 60% decrease in plant nodule nitrogenase activity. N fertilizer also reduced the proportion of cells in the root nodules containing N‐fixing vesicles in the forest site. Shrubs in the forest had the highest photosynthetic rate when measured on a leaf mass basis, indicating an increased carbon capture efficiency compared with shrubs in the open. Over the course of two growing seasons, soil temperature had a positive effect on specific nitrogenase activity, and soil in the open site was warmer than soil in the forest in the spring. However, as soil moisture decreased, temperature was a weaker predictor of nitrogenase activity. Although all shrubs consistently acquired most of their N from fixation, shrubs in the forest derived more than shrubs in the open, which were more water limited. Overall, these results show that N‐fixing plants may benefit from being in the understory for improved water balance in this region of the boreal forest. As such, light availability may not be the primary factor limiting the abundance of N‐fixing shrubs.

26508 Blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic neoplasm that arises from precursors of plasmacytoid dendritic cells. Clinical findings of BPDCN may be nondescript, making histologic evaluation, with the aid of immunohistochemical stains, essential. We present a case of a 76-year-old male with no known medical history who presented with chief complaint of a lesion on his chest. He previously thought the lesion was a bruise; however, when it failed to resolve, he sought medical evaluation. The patient denied personal or family history of hematologic malignancy. Thorough review of systems was negative with the exception of recent onset fatigue. Physical examination revealed a solitary, well-defined erythematous-to-violaceous plaque with a central nodular component on the patient’s chest. A 4-mm punch biopsy was obtained from the nodular component. Hematoxylin–eosin evaluation demonstrated dermal nodules of tumor cells extending into the fat with sparing of the overlying epidermis. Individual cells were oval in shape with dispersed nuclear chromatin and eccentric pink plasmacytoid-like cytoplasm. Immunohistochemistry staining was positive for CD123, CD56, and CD4, but negative for CD3, supporting a diagnosis of BPDCN. Subsequently, the patient was referred to hematology and oncology for systemic evaluation and treatment. Our case highlights a rare entity as well as underscores the importance of immunohistochemical stains in accurately diagnosing hematologic neoplasms with cutaneous manifestations. While rare, BPDCN represents an important diagnostic consideration for dermatologists as it most commonly presents in the integumentary system and early identification may impact treatment course and outcome.

Immunoinformatic approach employing modeling and simulation to design a novel vaccine construct targeting MDR efflux pumps to confer wide protection against typhoidal Salmonella serovars

Overcoming multi drug resistance is one of the crucial challenges to control enteric typhoid fever caused by Salmonella typhi and Salmonella paratyphi. Overexpression of efflux pumps predominantly causes drug resistance in microorganisms. Therefore, immunotherapy targeting the various efflux pumps antigens could be a promising strategy to increase the success of vaccines. An immunoinformatic approach was employed to design a Salmonellosis multi-epitope subunit vaccine peptide consisting of linear B-cell and T-cell epitopes of multidrug resistance protein families including ATP Binding Cassette (ABC), major facilitator superfamily (MFS), resistance nodulation cell division (RND), small multidrug resistance (SMR), and multidrug and toxin extrusion (MATE). The selected epitopes exhibited conservation in both S. typhi and S. paratyphi and thus could be helpful for cross-protection. Further, the final vaccine construct encompassing the peptides, adjuvants and specific linker sequences showed high immunogenicity, solubility, non-allergenic, nontoxic, and wide population coverage due to strong binding affinity to maximum HLA alleles. The three-dimensional structure was predicted, and validated using various structure validation tools. Additionally, protein-protein docking of the chimeric vaccine construct with the TLR-2 protein and molecular dynamics demonstrated stable and efficient binding. Conclusively, the immunoinformatic study showed that the novel multi epitopic vaccine construct can simulate the both T-cell and B-cell immune responses in typhoidal Salmonella serovars and could potentially be used for prophylactic or therapeutic applications. Communicated by Ramaswamy H. Sarma

Molecular Characterization of Carbonic Anhydrase Genes in Lotus japonicus and Their Potential Roles in Symbiotic Nitrogen Fixation.

Carbonic anhydrase (CA) plays a vital role in photosynthetic tissues of higher plants, whereas its non-photosynthetic role in the symbiotic root nodule was rarely characterized. In this study, 13 CA genes were identified in the model legume Lotus japonicus by comparison with Arabidopsis CA genes. Using qPCR and promoter-reporter fusion methods, three previously identified nodule-enhanced CA genes (LjαCA2, LjαCA6, and LjβCA1) have been further characterized, which exhibit different spatiotemporal expression patterns during nodule development. LjαCA2 was expressed in the central infection zone of the mature nodule, including both infected and uninfected cells. LjαCA6 was restricted to the vascular bundle of the root and nodule. As for LjβCA1, it was expressed in most cell types of nodule primordia but only in peripheral cortical cells and uninfected cells of the mature nodule. Using CRISPR/Cas9 technology, the knockout of LjβCA1 or both LjαCA2 and its homolog, LjαCA1, did not result in abnormal symbiotic phenotype compared with the wild-type plants, suggesting that LjβCA1 or LjαCA1/2 are not essential for the nitrogen fixation under normal symbiotic conditions. Nevertheless, the nodule-enhanced expression patterns and the diverse distributions in different types of cells imply their potential functions during root nodule symbiosis, such as CO2 fixation, N assimilation, and pH regulation, which await further investigations.