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The Journal of Clinical Endocrinology... Jun 2022Predictive models of thyroid nodule cancer risk are presently based upon nodule composition, echogenicity, margins, and the presence of microcalcifications. Nodule shape...
CONTEXT
Predictive models of thyroid nodule cancer risk are presently based upon nodule composition, echogenicity, margins, and the presence of microcalcifications. Nodule shape has shown promise to be an additive factor helping determine the need for nodule biopsy.
OBJECTIVE
We sought to determine if calculation of a nodule's spherical shape independently associates with cancer risk.
METHODS
This prospective cohort study, conducted at a single large academic healthcare system in the United States, included patients with 1 or 2 clinically relevant thyroid nodules (predominantly solid and over 1 cm) presenting for diagnostic evaluation. Thyroid ultrasound, cytological evaluation with fine-needle biopsy, and/or histopathological examination on occasion of thyroid surgery were performed. We calculated the nodule's long to short ratio (spherical shape), and its association with tissue proven benign or malignant endpoints.
RESULTS
The long to short nodule ratio was significantly lower in malignant compared to benign nodules indicating greater risk of malignancy in more spherical nodules (1.63 ± 0.38 for malignant nodules vs 1.74 ± 0.47 for benign, P < 0.0001). The risk of malignancy continually increased as the long to short ratio approached a purely spherical ratio of 1.0 (ratio > 2.00, 14.6% cancer; ratio 1.51-2.00, 19.7%; ratio 1.00-1.50, 25.5%, P < 0.0001). In multiple regression analysis, younger age, male sex, and nodule's spherical shape were each independently associated with cancer risk.
CONCLUSION
The more a thyroid nodule is spherically shaped, as indicated by a long to short ratio approaching 1.0, the greater its risk of malignancy. This was independent of age, sex, and nodule size. Incorporating a nodule's sphericity in the risk stratification systems may improve individualized clinical decision making.
Topics: Biopsy, Fine-Needle; Humans; Male; Prospective Studies; Retrospective Studies; Thyroid Neoplasms; Thyroid Nodule; Ultrasonography
PubMed: 35439309
DOI: 10.1210/clinem/dgac246 -
The New Phytologist Apr 2022The plant hormone gibberellin (GA) is required at different stages of legume nodule development, with its spatiotemporal distribution tightly regulated. Transcriptomic...
The plant hormone gibberellin (GA) is required at different stages of legume nodule development, with its spatiotemporal distribution tightly regulated. Transcriptomic and bioinformatic analyses established that several key GA biosynthesis and catabolism enzyme encoding genes are critical to soybean (Glycine max) nodule formation. We examined the expression of several GA oxidase genes and used a Förster resonance energy transfer-based GA biosensor to determine the bioactive GA content of roots inoculated with DsRed-labelled Bradyrhizobium diazoefficiens. We manipulated the level of GA by genetically disrupting the expression of GA oxidase genes. Moreover, exogenous treatment of soybean roots with GA induced the expression of key nodulation genes and altered infection thread and nodule phenotypes. GmGA20ox1a, GmGA3ox1a, and GmGA2ox1a are upregulated in soybean roots inoculated with compatible B. diazoefficiens. GmGA20ox1a expression is predominately localized to the transient meristem of soybean nodules and coincides with the spatiotemporal distribution of bioactive GA occurring throughout nodule organogenesis. GmGA2ox1a exhibits a nodule vasculature-specific expression pattern, whereas GmGA3ox1a can be detected throughout the nodule and root. Disruptions in the level of GA resulted in aberrant rhizobia infection and reduced nodule numbers. Collectively, our results establish a central role for GAs in root hair infection by symbiotic rhizobia and in nodule organogenesis.
Topics: Bradyrhizobium; Fabaceae; Gene Expression Regulation, Plant; Gibberellins; Plant Proteins; Plant Root Nodulation; Plant Roots; Root Nodules, Plant; Glycine max; Symbiosis
PubMed: 34870861
DOI: 10.1111/nph.17902 -
Annals of Botany Jun 2020Efficient biological nitrogen fixation (BNF) requires leghaemoglobin (Lb) to modulate oxygen pressure in nodules. Excess N supply severely inhibits BNF through effects...
BACKGROUND AND AIMS
Efficient biological nitrogen fixation (BNF) requires leghaemoglobin (Lb) to modulate oxygen pressure in nodules. Excess N supply severely inhibits BNF through effects on Lb during nodulation. As yet, a systematic identification and characterization of Lb-encoding genes in soybean has not been reported.
METHODS
The effects of N on BNF were studied in soybean plants inoculated with rhizobia and exposed to excess or low N availability in hydroponic cultures. To identify soybean Lb proteins, BLAST searches were performed on the Phytozome website. Bioinformatic analysis of identified GmLbs was then carried out to investigate gene structure, protein homology and phylogenetic relationships. Finally, quantitative real-time PCR was employed to analyse the expression patterns of soybean Lb genes in various tissues and in response to high N availability.
KEY RESULTS
Excess N significantly accelerated nodule senescence and the production of green Lb in nodules. In total, seven haemoglobin (Hb) genes were identified from the soybean genome, with these Hb genes readily split into two distinct clades containing predominantly symbiosis-associated or non-symbiotic Hb members. Expression analysis revealed that all of the symbiosis-associated Lbs except GmLb5 were specifically expressed in nodules, while the non-symbiotic GmHbs, GmHb1 and GmHb2, were predominantly expressed in leaves and roots, respectively. Among identified GmLbs, GmLb1-4 are the major Lb genes acting in soybean nodulation, and each one is also significantly suppressed by exposure to excess N.
CONCLUSIONS
Taken together, the results show that excess N inhibits BNF by reducing nodule formation, Lb concentration and nitrogenase activity. The characteristics of the entire Hb family were analysed, and we found that GmLb1-4 are closely associated with nodule development and N2 fixation. This works forms the basis for further investigations of the role of Lbs in soybean nodulation.
Topics: Gene Expression Regulation, Plant; Leghemoglobin; Nitrogen Fixation; Phylogeny; Plant Proteins; Plant Root Nodulation; Root Nodules, Plant; Glycine max; Symbiosis
PubMed: 32297921
DOI: 10.1093/aob/mcaa002 -
Biotechnology Advances Dec 2023Legumes enter into symbiotic associations with soil nitrogen-fixing rhizobia, culminating in the creation of new organs, root nodules. This complex process relies on... (Review)
Review
Legumes enter into symbiotic associations with soil nitrogen-fixing rhizobia, culminating in the creation of new organs, root nodules. This complex process relies on chemical and physical interaction between legumes and rhizobia, including early signalling events informing the host legume plant of a potentially beneficial microbe and triggering the nodulation program. The great significance of this plant-microbe interaction rests upon conversion of atmospheric dinitrogen not accessible to plants into a biologically active form of ammonia available to plants. The plant cytoskeleton consists in a highly dynamic network and undergoes rapid remodelling upon sensing various developmental and environmental cues, including response to attachment, internalization, and accommodation of rhizobia in plant root and nodule cells. This dynamic nature is governed by cytoskeleton-associated proteins that modulate cytoskeletal behaviour depending on signal perception and transduction. Precisely localized cytoskeletal rearrangements are therefore essential for the uptake of rhizobia, their targeted delivery, and establishing beneficial root nodule symbiosis. This review summarizes current knowledge about rhizobia-dependent rearrangements and functions of the cytoskeleton in legume roots and nodules. General patterns and nodule type-, nodule stage-, and species-specific aspects of actin filaments and microtubules remodelling are discussed. Moreover, emerging evidence is provided about fine-tuning the root nodulation process through cytoskeleton-associated proteins. We also consider future perspectives on dynamic localization studies of the cytoskeleton during early symbiosis utilizing state of the art molecular and advanced microscopy approaches. Based on acquired detailed knowledge of the mutualistic interactions with microbes, these approaches could contribute to broader biotechnological crop improvement.
Topics: Fabaceae; Symbiosis; Rhizobium; Cytoskeleton; Microtubules
PubMed: 37775072
DOI: 10.1016/j.biotechadv.2023.108263 -
Frontiers in Plant Science 2018Sulfur is an essential nutrient in plants as a constituent element of some amino acids, metal cofactors, coenzymes, and secondary metabolites. Not surprisingly, sulfur... (Review)
Review
Sulfur is an essential nutrient in plants as a constituent element of some amino acids, metal cofactors, coenzymes, and secondary metabolites. Not surprisingly, sulfur deficiency decreases plant growth, photosynthesis, and seed yield in both legumes and non-legumes. In nodulated legumes, sulfur supply is positively linked to symbiotic nitrogen fixation (SNF) and sulfur starvation causes three additional major effects: decrease of nodulation, inhibition of SNF, and slowing down of nodule metabolism. These effects are due, at least in part, to the impairment of nitrogenase biosynthesis and activity, the accumulation of nitrogen-rich amino acids, and the decline in leghemoglobin, ferredoxin, ATP, and glucose in nodules. During the last decade, some major advances have been made about the uptake and metabolism of sulfur in nodules. These include the identification of the sulfate transporter SST1 in the symbiosomal membrane, the finding that glutathione produced in the bacteroids and host cells is essential for nodule activity, and the demonstration that sulfur assimilation in the whole plant is reprogrammed during symbiosis. However, many crucial questions still remain and some examples follow. In the first place, it is of paramount importance to elucidate the mechanism by which sulfur deficiency limits SNF. It is unknown why homoglutahione replaces glutathione as a major water-soluble antioxidant, redox buffer, and sulfur reservoir, among other relevant functions, only in certain legumes and also in different tissues of the same legume species. Much more work is required to identify oxidative post-translational modifications entailing cysteine and methionine residues and to determine how these modifications affect protein function and metabolism in nodules. Likewise, most interactions of antioxidant metabolites and enzymes bearing redox-active sulfur with transcription factors need to be defined. Solving these questions will pave the way to decipher sulfur-dependent mechanisms that regulate SNF, thereby gaining a deep insight into how nodulated legumes adapt to the fluctuating availability of nutrients in the soil.
PubMed: 30364181
DOI: 10.3389/fpls.2018.01434 -
International Journal of Molecular... Jun 2022The formation and development of legumes nodules requires a lot of energy. Legumes must strictly control the number and activity of nodules to ensure efficient energy... (Review)
Review
The formation and development of legumes nodules requires a lot of energy. Legumes must strictly control the number and activity of nodules to ensure efficient energy distribution. The AON system can limit the number of rhizobia infections and nodule numbers through the systemic signal pathway network that the aboveground and belowground parts participate in together. It can also promote the formation of nodules when plants are deficient in nitrogen. The currently known AON pathway includes four parts: soil NO signal and signal recognition and transmission, CLE-SUNN is the negative regulation pathway, CEP-CRA2 is the positive regulation pathway and the miR2111/TML module regulates nodule formation and development. In order to ensure the biological function of this important approach, plants use a variety of plant hormones, polypeptides, receptor kinases, transcription factors and miRNAs for signal transmission and transcriptional regulation. This review summarizes and discusses the research progress of the AON pathway in Legume nodule development.
Topics: Fabaceae; Gene Expression Regulation, Plant; Homeostasis; Plant Proteins; Plant Root Nodulation; Rhizobium; Root Nodules, Plant; Self-Control; Symbiosis
PubMed: 35743118
DOI: 10.3390/ijms23126676 -
Plant Signaling & Behavior Feb 2009The formation of a nitrogen-fixing nodule involves two diverse developmental processes in the legume root: infection thread initiation in epidermal cells and nodule... (Review)
Review
The formation of a nitrogen-fixing nodule involves two diverse developmental processes in the legume root: infection thread initiation in epidermal cells and nodule primordia formation in the cortex. Several plant hormones have been reported to positively or negatively regulate nodulation. These hormones function at different stages in the nodulation process and may facilitate the coordinated development of the epidermal and cortical developmental programs that are necessary to allow bacterial infection into the developing nodule. In this paper, we review and discuss how the tissue specific nature of hormonal action dictates where, when and how a nodule is formed.
Topics: Gene Expression Regulation, Plant; Nitrogen Fixation; Plant Epidermis; Plant Growth Regulators; Root Nodules, Plant; Symbiosis
PubMed: 19649179
DOI: 10.4161/psb.4.2.7693 -
The New Phytologist Jul 2017Contents 40 I. 40 II. 41 III. 44 IV. 48 V. 49 VI. 49 VII. 52 VIII. 53 53 References 53 SUMMARY: In the last decade, analyses of both molecular and morphological... (Review)
Review
Contents 40 I. 40 II. 41 III. 44 IV. 48 V. 49 VI. 49 VII. 52 VIII. 53 53 References 53 SUMMARY: In the last decade, analyses of both molecular and morphological characters, including nodulation, have led to major changes in our understanding of legume taxonomy. In parallel there has been an explosion in the number of genera and species of rhizobia known to nodulate legumes. No attempt has been made to link these two sets of data or to consider them in a biogeographical context. This review aims to do this by relating the data to the evolution of the two partners: it highlights both longitudinal and latitudinal trends and considers these in relation to the location of major land masses over geological time. Australia is identified as being a special case and latitudes north of the equator as being pivotal in the evolution of highly specialized systems in which the differentiated rhizobia effectively become ammonia factories. However, there are still many gaps to be filled before legume nodulation is sufficiently understood to be managed for the benefit of a world in which climate change is rife.
Topics: Biodiversity; Biological Evolution; Fabaceae; Nitrogen Fixation; Phylogeography; Root Nodules, Plant; Symbiosis
PubMed: 28211601
DOI: 10.1111/nph.14474 -
Plant Physiology Nov 2018Nodulation is crucial for biological nitrogen fixation (BNF) in legumes, but the molecular mechanisms underlying BNF have remained elusive. Here, we cloned a candidate...
Nodulation is crucial for biological nitrogen fixation (BNF) in legumes, but the molecular mechanisms underlying BNF have remained elusive. Here, we cloned a candidate gene underlying a major nodulation quantitative trait locus in soybean (), (). encodes a cell wall β-expansin and is expressed primarily in vascular bundles, along with cortical and parenchyma cells of nodules. Four single-nucleotide polymorphisms distinguishing the two parents were found in the promoter region. Among them, single-nucleotide polymorphism A/C has a significant effect on expression in the parental genotype P2, based on β-glucuronidase activity and promoter deletion analysis. The expression of and the P2 genotype promoter was strongly associated with nodule development, not only in the parents but also in 40 progeny lines and 40 genotypes selected from a soybean core collection. Overexpression of resulted in increases in the number, biomass, infection cell abundance, and nitrogenase activity of large nodules and subsequently changed the nitrogen content and biomass of soybean plants. suppression via RNA interference had the opposite effect. Double suppression of and dramatically inhibited soybean nodulation. Our results reveal that is a critical gene in nodule development and that and synergistically control nodulation in soybean. Our findings shed light on the genetic basis of soybean nodulation and provide a candidate gene for optimizing BNF capacity through molecular breeding in soybean.
Topics: Cell Wall; Genes, Reporter; Nitrogen; Nitrogen Fixation; Plant Proteins; Plant Root Nodulation; Promoter Regions, Genetic; RNA Interference; Rhizobium; Root Nodules, Plant; Sequence Deletion; Glycine max; Symbiosis
PubMed: 30266750
DOI: 10.1104/pp.18.01018 -
Plant, Cell & Environment May 2021Legumes control their nodule numbers through the autoregulation of nodulation (AON). Rhizobia infection stimulates the production of root-derived CLE peptide hormones...
Legumes control their nodule numbers through the autoregulation of nodulation (AON). Rhizobia infection stimulates the production of root-derived CLE peptide hormones that are translocated to the shoot where they regulate a new signal. We used soybean to demonstrate that this shoot-derived signal is miR2111, which is transported via phloem to the root where it targets transcripts of Too Much Love (TML), a negative regulator of nodulation. Shoot perception of rhizobia-induced CLE peptides suppresses miR2111 expression, resulting in TML accumulation in roots and subsequent inhibition of nodule organogenesis. Feeding synthetic mature miR2111 via the petiole increased nodule numbers per plant. Likewise, elevating miR2111 availability by over-expression promoted nodulation, while target mimicry of TML induced the opposite effect on nodule development in wild-type plants and alleviated the supernodulating and stunted root growth phenotypes of AON-defective mutants. Additionally, in non-nodulating wild-type plants, ectopic expression of miR2111 significantly enhanced lateral root emergence with a decrease in lateral root length and average root diameter. In contrast, hairy roots constitutively expressing the target mimic construct exhibited reduced lateral root density. Overall, these findings demonstrate that miR2111 is both the critical shoot-to-root factor that positively regulates root nodule development and also acts to shape root system architecture.
Topics: Amino Acid Sequence; Base Sequence; Gene Expression Regulation, Plant; MicroRNAs; Models, Biological; Multigene Family; Phenotype; Phloem; Plant Proteins; Plant Shoots; RNA, Messenger; Rhizobium; Root Nodules, Plant; Glycine max; Transcription, Genetic
PubMed: 33386621
DOI: 10.1111/pce.13992