Suppression of innate immunity is essential for rhizobial infection and colonization in compatible interactions with leguminous plants. In Medicago nad1 mutant plants, innate immunity is excessively ...activated, resulting in necrotic cell death after rhizobia are released from infection threads into symbiotic cells, suggesting that innate immunity plays a critical role in regulating bacteroid persistence.
In this study, we identified three respiratory burst oxidase homologs (Rboh) and one calcium-dependent protein kinase (CDPK) as key factors for the activation of immunity in Medicago nodules using genetic and biochemical methods.
Knock-out of either MtRbohB or MtRbohD in nad1-1 mutant plants produced effective nodules with intact symbiotic cells, while knock-out of MtRbohC decreased brown pigment deposition, leading to less necrosis in nad1-1 mutant nodules. MtCDPK5 directly phosphorylated MtRbohB, MtRbohC and MtRbohD, which triggered immune responses in plants. Knock-out of MtCDPK5 in nad1-1 mutant plants partially restored nitrogen-fixing nodules.Overexpression of the constitutively activated variant MtCDPK5
VK under the control of the NAD1 promoter elicited strong immune responses, resulting in ineffective nodules in wild-type plants.
Our data provide direct evidence that host plants utilize innate immunity to regulate rhizobial colonization in symbiotic cells in Medicago truncatula.
Potent and selective inhibition of the structurally homologous proteases of coagulation poses challenges for drug development. Hematophagous organisms frequently accomplish this by fashioning peptide ...inhibitors combining exosite and active site binding motifs. Inspired by this biological strategy, we create several EXACT inhibitors targeting thrombin and factor Xa de novo by linking EXosite-binding aptamers with small molecule ACTive site inhibitors. The aptamer component within the EXACT inhibitor (1) synergizes with and enhances the potency of small-molecule active site inhibitors by many hundred-fold (2) can redirect an active site inhibitor's selectivity towards a different protease, and (3) enable efficient reversal of inhibition by an antidote that disrupts bivalent binding. One EXACT inhibitor, HD22-7A-DAB, demonstrates extraordinary anticoagulation activity, exhibiting great potential as a potent, rapid onset anticoagulant to support cardiovascular surgeries. Using this generalizable molecular engineering strategy, selective, potent, and rapidly reversible EXACT inhibitors can be created against many enzymes through simple oligonucleotide conjugation for numerous research and therapeutic applications.
Biomineralization occurs in natural organisms, such as bones, teeth, shells and tendons. The formation mechanism and mechanical properties have been extensively studied for mineralized hard tissues, ...especially for bone and teeth. However, the research on the evolution of mechanical properties for mineralized soft tissues remains challenging due to the long period of mineralization. Here we use polymer-induced liquid-precursor (PILP) method to achieve accelerated in vitro mineralization of bovine pericardium with SrCO3. The modulus, tensile strength, toughness, and suture retention force of mineralized tissues have been characterized. After 30 days of mineralization, both the tensile strength and toughness decrease by two orders of magnitude. We carry out cyclic suture retention test to characterize the fatigue properties of mineralized tissues, and find that the cycle to failure of mineralized tissues is 10-100 times lower than that of unmineralized tissues. The degradation of mechanical properties results from the microstructure change of mineralized tissues, where collagen fibers change from curled to straight configuration. After mineralization, the interfibrous slippage is limited, and the fracture mode changes from fiber pullout to fiber break. Finite element analysis has been carried out to simulate the fracture and suture retention properties, and the simulation can well reproduce experimental results. The study may provide insights for tissue replacement and repairing.
Display omitted
Resistance genes (R genes) are a class of genes that are immune to a wide range of diseases and pests. In planta, NLR genes are essential components of the innate immune system. Currently, genes ...belonging to NLR family have been found in a number of plant species, but little is known in peach. Here, 286 NLR genes were identified on peach genome by using their homologous genes in Arabidopsis thaliana as queries. These 286 NLR genes contained at least one NBS domain and LRR domain. Phylogenetic and N-terminal domain analysis showed that these NLRs could be separated into four subfamilies (I-IV) and their promoters contained many cis-elements in response to defense and phytohormones. In addition, transcriptome analysis showed that 22 NLR genes were up-regulated after infected by Green Peach Aphid (GPA), and showed different expression patterns. This study clarified the NLR gene family and their potential functions in aphid resistance process. The candidate NLR genes might be useful in illustrating the mechanism of aphid resistance in peach.
Suppression of host innate immunity appears to be required for the establishment of symbiosis between rhizobia and host plants. In this study, we established a system that included a host plant, a ...bacterial pathogen and a symbiotic rhizobium to study the role of innate immunity during symbiotic interactions. A pathogenic bacterium,
pv.
strain DC3000 (
DC3000), was shown to cause chlorosis in
A17.
strain Sm2011 (Sm2011) and
DC3000 strain alone induced similar defense responses in
However, when co-inoculated, Sm2011 specifically suppressed the defense responses induced by
DC3000, such as MAPK activation and ROS production. Inoculation with Sm2011 suppressed the transcription of defense-related genes triggered by
DC3000 infection, including the receptor of bacterial flagellin (
), pathogenesis-related protein 10 (
), and the transcription factor
. Interestingly, inoculation with
DC3000 specifically inhibited the expression of the symbiosis marker genes
and
and reduced the numbers of infection threads and nodules on
A17 roots, indicating that
DC3000 inhibits the establishment of symbiosis in
In addition, defense-related genes, such as
,
, exhibited a transient increase in their expression in the early stage of symbiosis with Sm2011, but the expression dropped down to normal levels at later symbiotic stages. Our results suggest that plant innate immunity plays an antagonistic role in symbiosis by directly reducing the numbers of infection threads and nodules.
Vascular smooth muscle cell (VSMC) apoptosis occurs at low levels in atherosclerotic plaques and in vessel remodeling; however, the consequences and mediators of these levels are not known. Akt1 ...protects against VSMC apoptosis largely through inactivating target proteins such as forkhead class O transcription factor 3a (FoxO3a), but Akt1 signaling is reduced and FoxO3a activity is increased in human atherosclerosis. We therefore sought to determine whether inhibition of VSMC apoptosis via Akt1 activation regulates vessel remodeling and atherogenesis and to identify FoxO3a target proteins that mediate VSMC apoptosis.
We generated mice that express an Akt1 protein that can be activated specifically in arterial VSMCs. Akt1 activation did not affect normal arteries, but inhibited VSMC apoptosis and negative remodeling after carotid ligation, indicating that VSMC apoptosis is a major determinant of vessel caliber after changes in flow. Akt1 activation inhibited VSMC apoptosis during atherogenesis and increased relative fibrous cap area in plaques. Microarray studies identified multiple FoxO3a-regulated genes involved in VSMC apoptosis, including apoptotic protease activating factor 1 as a novel target. Apoptotic protease activating factor 1 mediated the proapoptotic activity of FoxO3a, was increased in human atherosclerosis, but reduced by Akt1 activity in vivo.
Akt1 is a major regulator of VSMC survival in vivo during vessel remodeling and atherogenesis, mediated in large part through inhibition of FoxO3a and its downstream genes, including apoptotic protease activating factor 1. Our data suggest that even the low-level VSMC apoptosis seen during changes in flow determines vessel wall structure and promotes fibrous cap thinning during atherogenesis.
• Expression of Nodule Inception (NIN) is essential for initiation of legume–rhizobial symbiosis. An existing model regarding the regulation of NIN expression involves two GRAS transcription factors ...– NSP1 (Nodulation Signaling Pathway 1) and NSP2. NSP2 forms a complex with NSP1 to directly bind to NIN promoter. However, rhizobial treatment-induced NIN expression could still be detected in the nsp1 mutant plants, suggesting that other proteins must be involved in the regulation of NIN expression.
• A combination of molecular, biochemical and genetic analyses was used to investigate the molecular basis of IPN2 in regulating root development and NIN expression in Lotus japonicus.
• In this study, we identified that IPN2 is a close homolog of Arabidopsis APL (ALTERED PHLOEM DEVELOPMENT) with essential function in root development. However, Lotus IPN2 has a different expression pattern compared with the Arabidopsis APL gene. IPN2 binds to the IPN2-responsive cis element (IPN2-RE) of NIN promoter and activates NIN expression. IPN2, NSP1 and NSP2 form a protein complex to directly target NIN promoter and activate NIN expression in the legume–rhizobial symbiosis.
• Our data refine the regulatory model of NIN expression that NSP2 works together with NSP1 and IPN2 to activate the NIN gene allowing nodulation in L. japonicus.
The bio-resource utilization of sewage sludge is presented by preparation of novel waste sludge–doped graphite carbon nitride (
g
-C
3
N
4
) photocatalyst. The sludge flocs which constitute bacteria ...and organic substances served as a pore-forming framework in the catalyst, while the inorganic fractions including those transition metals and crustal metals can function as dopants for sludge-based
g-
C
3
N
4
composite. The physicochemical properties of as-prepared catalyst were well analyzed by multiple characterizations. The composite catalyst showed higher surface area (50 m
2
/g) and more mesoporous structures (8.9 × 10
−2
cm
3
/g) as compared with pristine g-C
3
N
4
(8.4 m
2
/g and 6.6 × 10
−2
cm
3
/g, respectively). The photoelectrochemical results showed that introduced sewage sludge impurities lowered down the photocarriers recombination efficiency and enhanced more efficient electron-hole separation by about 100 times. The photocatalytic activity was tested by degradation of typical dye Eriochrome Black T (EBT). The optimal sample improved removal of EBT by 56% in 90 min under ultraviolet irradiation (
λ
= 254 nm). According to the results of main metal ion leaching concentration and reuse tests, the composite catalyst exhibited excellent stability and repeatability.
Phytosulfokine (PSK) is a tyrosine-sulfated peptide that is widely distributed in plants, participating in cell proliferation, differentiation, and innate immunity. The potential role of PSK in ...nodulation in legumes has not been reported. In this work, five PSK precursor genes were identified in Lotus japonicas, designated as LjPSK1 to LjPSK5. Three of them (LjPSK1, LjPSK4, and LjPSK5) were found to be expressed in nitrogen-fixing root nodules. LjPSK1 and LjPSK4 were not induced at the early stage of nodulation. Interestingly, while the expression of LjPSK4 was also found in spontaneous nodules without rhizobial colonization, LjPSK1 was not induced in these pseudo nodules. Promoter-β-glucuronidase analysis revealed that LjPSK1 was highly expressed in enlarged symbiotic cells of nodules. Exogenous addition of 1 1M synthetic PSK peptide resulted in increased nodule numbers per plant. Consistently, the number of mature nodules but not the events of rhizobial infection and nodule initiation was increased by overexpressing LjPSK1 in transgenic hairy roots, in which the expression of jasmonate-responsive genes was found to be repressed. These results suggest that PSK is a new peptide signal that regulates nodulation in legumes, probably through cross-talking with other phytohormones.
This study specifically focused on Litopenaeus vannamei and examined the distribution of residual antibiotics in various components of shrimp ponds throughout an aquaculture cycle. The findings ...revealed that aquaculture feed served as the primary source of antibiotics, continuously introducing them into the ponds throughout the entire production cycle. A multimedia distribution model for antibiotics in the ponds was established based on the principle of mass balance. The distribution characteristics of six antibiotics with higher levels in the feed, namely, sulfamethoxazole (SMX), norfloxacin (NOF), levofloxacin (LEOF), tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC), were investigated in the pond water, sediment, and shrimp. At the end of the cultivation period, the total antibiotic residues accounted for 65~80% in various media, with the sediment containing 50~60% of the distribution proportion (p < 0.01), which was identified as the primary reservoir for most antibiotics, with LEOF and NOF accounting for the highest proportions (45.78% and 50.29%, respectively). Based on the model’s findings and the allowable daily dosage of antibiotics, recommendations were made for the effective control of antibiotic residues in shrimp farming management. To address the significant net loss of sulfonamides (SAs) and tetracyclines (TCs) in aquaculture production, it is crucial to carefully regulate their dosages and administration methods. Implementing eco-friendly additives and regularly cleaning surface sediments can aid in reducing antibiotic residue levels in various environmental media, thereby mitigating the environmental impact on aquaculture production activities.
PDF
