Identification of a Dominant Gene in Medicago truncatula That Restricts Nodulation by Sinorhizobium meliloti Strain Rm41

BACKGROUND: Leguminous plants are able to form a root nodule symbiosis with nitrogen-fixing soil bacteria called rhizobia. This symbiotic association shows a high level of specificity. Beyond the specificity for the legume family, individual legume species/genotypes can only interact with certain restricted group of bacterial species or strains. Specificity in this system is regulated by complex signal exchange between the two symbiotic partners and thus multiple genetic mechanisms could be involved in the recognition process. Knowledge of the molecular mechanisms controlling symbiotic specificity could enable genetic improvement of legume nitrogen fixation, and may also reveal the possible mechanisms that restrict root nodule symbiosis in non-legumes. RESULTS: We screened a core collection of Medicago truncatula genotypes with several strains of Sinorhizobium meliloti and identified a naturally occurring dominant gene that restricts nodulation by S. meliloti Rm41. We named this gene as Mt-NS1 (for M.truncatulanodulation specificity 1). We have mapped the Mt-NS1 locus within a small genomic region on M. truncatula chromosome 8. The data reported here will facilitate positional cloning of the Mt-NS1 gene. CONCLUSIONS: Evolution of symbiosis specificity involves both rhizobial and host genes. From the bacterial side, specificity determinants include Nod factors, surface polysaccharides, and secreted proteins. However, we know relatively less from the host side. We recently demonstrated that a component of this specificity in soybeans is defined by plant NBS-LRR resistance (R) genes that recognize effector proteins delivered by the type III secretion system (T3SS) of the rhizobial symbionts. However, the lack of a T3SS in many sequenced S. meliloti strains raises the question of how the specificity is regulated in the Medicago-Sinorhizobium system beyond Nod-factor perception. Thus, cloning and characterization of Mt-NS1 will add a new dimension to our knowledge about the genetic control of nodulation specificity in the legume-rhizobial symbiosis

Efectos del cobre disuelto sobre la supervivencia, estado antioxidante, expresión de la metalotionina-I mRNA y la respuesta fisiológica de las larvas del cangrejo de Shangai, Eriocheir sinensis (Decapoda: Brachyura)

The lethal concentration of water-borne copper in Chinese mitten crab Eriocheir sinensis larvae was tested by exposing the animals to 0, 0.1, 0.2, 0.3, 0.5 and 0.8 mg Cu L-1 at 20°C for 96 h. The 96-h median lethal concentration (LC50) and its corresponding 95% confident interval was estimated on zoea 1 larvae and megalopa larvae, respectively. Acute dissolved copper toxicity was higher for zoea 1 larvae (0.16 mg L-1) than for megalopa larvae (0.21 mg L-1). The antioxidant status, metallothionein-I mRNA expression and physiological response of the crab to copper toxicity was further investigated by exposing the megalopa larvae to 0, 0.08 and 0.16 mg Cu L-1 for 96 h. The superoxide dismutase activity, catalase activity, glutathione S-transferase (GST) activity and lipid peroxidation content of megalopa larvae increased concomitantly with the exposure time and copper concentration. MT-I mRNA expression levels were positively correlated with both the concentration and duration of copper exposure. The oxygen consumption and respiratory quotient of megalopa larvae in response to 0.16 mg L-1 copper were significantly higher than those in the control group after 96 h of exposure (P < 0.05). The results of this study highlight the potential effects of copper as a common stressor in E. sinensis larvae. MT-I and GST appear to be suitable biomarkers of environmental copper exposure stress in E. sinensis larvaeLa concentración letal de cobre disuelto se determina mediante la exposición de larvas del cangrejo de Shangai (Eriocheir sinensis) a dosis de 0, 0.1, 0.2, 0.3, 0.5 y 0.8 mg Cu L–1, a 20°C durante 96 h. La concentración letal media (LC50) y su correspondiente intervalo de confianza del 95% fueron estimados en los estadios larvales zoea I y megalopa. La toxicidad aguda del cobre disuelto fue mayor sobre larvas de zoea I (0.16 mg L–1) que sobre las de megalopa (0.21 mg L–1). El estado antioxidante, la expresión del mRNA de la metalotionina–I y la respuesta fisiológica del cangrejo a la toxicidad del cobre fueron posteriormente investigados exponiendo las larvas de megalopa a dosis de 0, 0.08 y 0.16 mg Cu L–1 durante 96 h. La actividad de la superóxido dismutasa (SOD), de la catalasa (CAT), de la glutatión-S-transferasa (GST) y la peroxidación lipídica de las larvas de megalopa se incrementó en relación con el tiempo de exposición y la concentración de cobre. Los niveles de expresión de MT-1 mRNA se correlacionaron positivamente con la concentración de cobre y el tiempo de exposición. El consumo de oxígeno y la tasa respiratoria de las larvas de megalopa fueron significativamente más elevadas que las del grupo control (P < 0.05) en respuesta a dosis de 0.16 mg Cu L–1, durante 96 h de exposición. Los resultados presentados en este estudio ponen de manifiesto los efectos potenciales del cobre como factor de estrés sobre las larvas de E. sinensis. MT-I y GST parecen ser adecuados biomarcadores de estrés a la exposición de Cu ambiental en larvas de E. sinensis

The Soybean \u3cem\u3eRfg1\u3c/em\u3e Gene Restricts Nodulation by \u3cem\u3eSinorhizobium fredii\u3c/em\u3e USDA193

Sinorhizobium fredii is a fast-growing rhizobial species that can establish a nitrogen-fixing symbiosis with a wide range of legume species including soybeans (Glycine max). In soybeans, this interaction shows a high level of specificity such that particular S. fredii strains nodulate only a limited set of plant genotypes. Here we report the identification of a dominant gene in soybeans that restricts nodulation with S. fredii USDA193. Genetic mapping in an F2 population revealed co-segregation of the underlying locus with the previously cloned Rfg1 gene. The Rfg1 allele encodes a member of the Toll-interleukin receptor/nucleotide-binding site/leucine-rich repeat class of plant resistance proteins that restricts nodulation by S. fredii strains USDA257 and USDA205, and an allelic variant of this gene also restricts nodulation by Bradyrhizobium japonicum USDA122. By means of complementation tests and CRISPR/Cas9-mediated gene knockouts, we demonstrate that the Rfg1 allele also is responsible for resistance to nodulation by S. fredii USDA193. Therefore, the Rfg1 allele likely provides broad-spectrum resistance to nodulation by many S. fredii and B. japonicum strains in soybeans

DCPT: Darkness Clue-Prompted Tracking in Nighttime UAVs

Existing nighttime unmanned aerial vehicle (UAV) trackers follow an "Enhance-then-Track" architecture - first using a light enhancer to brighten the nighttime video, then employing a daytime tracker to locate the object. This separate enhancement and tracking fails to build an end-to-end trainable vision system. To address this, we propose a novel architecture called Darkness Clue-Prompted Tracking (DCPT) that achieves robust UAV tracking at night by efficiently learning to generate darkness clue prompts. Without a separate enhancer, DCPT directly encodes anti-dark capabilities into prompts using a darkness clue prompter (DCP). Specifically, DCP iteratively learns emphasizing and undermining projections for darkness clues. It then injects these learned visual prompts into a daytime tracker with fixed parameters across transformer layers. Moreover, a gated feature aggregation mechanism enables adaptive fusion between prompts and between prompts and the base model. Extensive experiments show state-of-the-art performance for DCPT on multiple dark scenario benchmarks. The unified end-to-end learning of enhancement and tracking in DCPT enables a more trainable system. The darkness clue prompting efficiently injects anti-dark knowledge without extra modules. Code and models will be released.Comment: Under revie

A STUDY ON THE INHIBITORY EFFECT OF MATRINE ON GASTRIC CANCER SGC-7901 CELLS

The objective of this paper was to investigate the antitumour mechanism of action of matrine by studying its inhibitory effect on gastric cancer SGC-7901 cells. SGC-7901 cells were chosen, and cell-killing capacity of matrine on gastric cancer SGC-7901 cells was determined using MTT assay and single PI staining assay. The results showed that matrine had an inhibitory effect on gastric cancer SGC-7901 cells, which was somewhat dose-dependent. The study concluded that matrine has a significant in-vitro inhibitory effect on SGC-7901 tumour cells, influences cell cycle of SGC-7901 cells, and induces their apoptosis

Adenoid lymphocyte heterogeneity in pediatric adenoid hypertrophy and obstructive sleep apnea

IntroductionAdenoid hypertrophy is the main cause of obstructive sleep apnea in children. Previous studies have suggested that pathogenic infections and local immune system disorders in the adenoids are associated with adenoid hypertrophy. The abnormalities in the number and function of various lymphocyte subsets in the adenoids may play a role in this association. However, changes in the proportion of lymphocyte subsets in hypertrophic adenoids remain unclear.MethodsTo identify patterns of lymphocyte subsets in hypertrophic adenoids, we used multicolor flow cytometry to analyze the lymphocyte subset composition in two groups of children: the mild to moderate hypertrophy group (n = 10) and the severe hypertrophy group (n = 5).ResultsA significant increase in naïve lymphocytes and a decrease in effector lymphocytes were found in severe hypertrophic adenoids.DiscussionThis finding suggests that abnormal lymphocyte differentiation or migration may contribute to the development of adenoid hypertrophy. Our study provides valuable insights and clues into the immunological mechanism underlying adenoid hypertrophy

Problematic Stabilizing Films in Petroleum Emulsions: Shear Rheological Response of Viscoelastic Asphaltene Films and the Effect on Drop Coalescence

Adsorption of asphaltenes at the water-oil interface contributes to the stability of petroleum emulsions by forming a networked film that can hinder drop-drop coalescence. The interfacial microstructure can either be liquid-like or solid-like, depending on (i) initial bulk concentration of asphaltenes, (ii) interfacial aging time, and (iii) solvent aromaticity. Two techniques--interfacial shear rheology and integrated thin film drainage apparatus--provided equivalent interface aging conditions, enabling direct correlation of the interfacial rheology and droplet stability. The shear rheological properties of the asphaltene film were found to be critical to the stability of contacting drops. With a viscous dominant interfacial microstructure, the coalescence time for two drops in intimate contact was rapid, on the order of seconds. However, as the elastic contribution develops and the film microstructure begins to be dominated by elasticity, the two drops in contact do not coalescence. Such step-change transition in coalescence is thought to be related to the high shear yield stress (~10(4) Pa), which is a function of the film shear yield point and the film thickness (as measured by quartz crystal microbalance), and the increased elastic stiffness of the film that prevents mobility and rupture of the asphaltene film, which when in a solid-like state provides an energy barrier against drop coalescence

Coupling and Cyclization of <i>o</i>‑Iodoanilines and Propargylic Bromides via Allenes: An Efficient Entry to Indomethacin

A sequential allene synthesis and cyclization has been realized in a one-pot manner. A Pd(0)-catalyzed one-pot reaction of <i>N</i>-Ts or -Ms 2-iodoanilines and propargylic bromides afforded indoles with pharmaceutical importance highly efficiently with diversity via sequential carbon–carbon bond coupling forming allenes and azapalladation. With this newly established methodology, an efficient approach to indomethacin, an anti-inflammatory drug (NSAID), has been accomplished

Efficient Carbazole Synthesis via Pd/Cu-Cocatalyzed Cross-Coupling/Isomerization of 2‑Allyl-3-iodoindoles and Terminal Alkynes

The Pd/Cu-cocatalyzed one-pot reaction of 2-allyl-3-iodo-1-tosyl-1<i>H</i>-indoles and terminal alkynes afforded carbazoles highly efficiently via sequential carbon–carbon coupling, isomerization, cyclization, and aromatization forming a benzene ring. Both Pd and Cu are responsible for the coupling step, while K₂CO₃ was observed to be critical for the subsequent cyclization