The α-proteobacterium Sinorhizobium meliloti establishes a chronic intracellular infection during the symbiosis with its legume hosts. Within specialized host cells, S. meliloti differentiates into ...highly polyploid, enlarged nitrogen-fixing bacteroids. This differentiation is driven by host cells through the production of defensin-like peptides called “nodule-specific cysteine-rich” (NCR) peptides. Recent research has shown that synthesized NCR peptides exhibit antimicrobial activity at high concentrations but cause bacterial endoreduplication at sublethal concentrations. We leveraged synchronized S. meliloti populations to determine how treatment with a sublethal NCR peptide affects the cell cycle and physiology of bacteria at the molecular level. We found that at sublethal levels a representative NCR peptide specifically blocks cell division and antagonizes Z-ring function. Gene-expression profiling revealed that the cell division block was produced, in part, through the substantial transcriptional response elicited by sublethal NCR treatment that affected ∼15% of the genome. Expression of critical cell-cycle regulators, including ctrA , and cell division genes, including genes required for Z-ring function, were greatly attenuated in NCR-treated cells. In addition, our experiments identified important symbiosis functions and stress responses that are induced by sublethal levels of NCR peptides and other antimicrobial peptides. Several of these stress-response pathways also are found in related α-proteobacterial pathogens and might be used by S. meliloti to sense host cues during infection. Our data suggest a model in which, in addition to provoking stress responses, NCR peptides target intracellular regulatory pathways to drive S. meliloti endoreduplication and differentiation during symbiosis.
Far from the world, the island is the world: The island ecotones of the Indian Ocean between creolisation and liquid borders. Due to their specific geography and plural histories, the island ...societies of the south-western Indian Ocean are characterised by a considerable anthropological and cultural complexity. Colonial regimes and migratory and diasporic phenomena have strongly marked these territories on the oceanic borders as well as their social construction and particular ethno-racial composition. Island-as-utopia, island-as-prison, island-as-refuge, island-as-stopover, island-as-relation, island-as-world … there is no shortage of notions to imagine and describe these heterogeneous places where the realities, potentialities, and limits of (post)colonial cultural plurality are negotiated. For behind the tropical dreams and the exaltations of harmonious cohabitation (vivre-ensemble) appear the precariousness of the island condition, the ambiguity of identity, and the difficulty of anchoring oneself in and expressing oneself from a place which continues to be significantly shaped by its relations with the outside (the old and new ‘metropolises’ and places of reference, other islands). To what extent can the specificities of the Indian Ocean islands – this other ‘archipelago’ less visible than its Caribbean counterpart – inform and nourish continental territories, France, the world? Are they models of ethical solidarity? Antidotes to identity-based blockages? Laboratories of democratic thought? Creative prefigurations of the future? It may well be. However, according to certain thinkers, writers and artists from these spaces, the islands and archipelagos – far from being the idealisations of a vitalist and blissful community (en-commun) – prove to be above all plural and conflicting contact zones. They emerge as complex ecotones that allow us to imagine and think about the challenges of our contemporary societies and cultures from the ‘margins’, the interstices, the unstable borders.
Abstract
Rhizobial soil bacteria can form a symbiosis with legumes in which the bacteria fix atmospheric nitrogen into ammonia that can be utilized by the host. The plant, in turn, supplies the ...rhizobia with a carbon source. After infecting the host cell, the bacteria differentiate into a distinct bacteroid form, which is able to fix nitrogen. The bacterial BacA protein is essential for bacteroid differentiation in legumes producing nodule-specific cysteine-rich peptides (NCRs), which induce the terminal differentiation of the bacteria into bacteroids. NCRs are antimicrobial peptides similar to mammalian defensins, which are important for the eukaryotic response to invading pathogens. The BacA protein is essential for rhizobia to survive the NCR peptide challenge. Similarities in the lifestyle of intracellular pathogenic bacteria suggest that host factors might also be important for inducing chronic infections associated with Brucella abortus and Mycobacterium tuberculosis. Moreover, rhizobial lipopolysaccharide is modified with an unusual fatty acid, which plays an important role in protecting the bacteria from environmental stresses. Mutants defective in the biosynthesis of this fatty acid display bacteroid development defects within the nodule. In this review, we will focus on these key components, which affect rhizobial bacteroid development and survival.
Rhizobia differentiate from free-living soil bacteria to nitrogen fixing endosymbionts of legume plants requiring specific adaptations for chronic maintenance.
Abstract Purpose Customised individually made (CIM) total knee arthroplasty (TKA) with personalised alignment is relatively new and evidence is limited. The aim of this study was to compare ...patient‐reported outcome measures between CIM and off‐the‐shelf (OTS) TKA patients in a matched‐pair analysis with a 2‐year follow‐up. Methods In this single‐centre, prospective cohort study, propensity score matching was performed on 51 CIM and 51 OTS TKA. Data were measured at baseline, at 4 months, 1 and 2 years and included the Forgotten Joint Score (FJS‐12), the High Activity Arthroplasty Score (HAAS), the Knee injury and Osteoarthritis Outcome Score (KOOS), the EQ‐5D‐3L, the EQ‐Visual Analogue Scale, satisfaction, overall knee improvement, willingness to undergo the surgery again and the Knee Society Score. Results At 2 years follow‐up, the FJS‐12 (77 vs. 67, p = .058), HAAS (13 vs. 11, p < .001), KOOS daily living (92 vs. 86, p = .029), KOOS sport (76 vs. 65, p = .019), KOOS quality of life (81 vs. 71, p = .028) and the EQ‐5D (.95 vs. .90, p = .030) were higher for CIM TKA compared to OTS TKA. Satisfaction rate was 92% for CIM TKA and 84% for OTS TKA ( p = .357). Most patients reported an improvement in the overall knee state (94% CIM and 90% OTS, p = .487) and almost all patients would undergo the surgery again (96% CIM and 98% OTS, p = .999). Conclusion The current study found that CIM TKA patients had better functional outcomes at 2 years. Patient satisfaction was high and not statistically significantly different from OTS TKA patients. Level of Evidence Level II prospective cohort study.
YbeY, a highly conserved protein, is an RNase in E. coli and plays key roles in both processing of the critical 3' end of 16 S rRNA and in 70 S ribosome quality control under stress. These central ...roles account for YbeY's inclusion in the postulated minimal bacterial genome. However, YbeY is not essential in E. coli although loss of ybeY severely sensitizes it to multiple physiological stresses. Here, we show that YbeY is an essential endoribonuclease in Vibrio cholerae and is crucial for virulence, stress regulation, RNA processing and ribosome quality control, and is part of a core set of RNases essential in most representative pathogens. To understand its function, we analyzed the rRNA and ribosome profiles of a V. cholerae strain partially depleted for YbeY and other RNase mutants associated with 16 S rRNA processing; our results demonstrate that YbeY is also crucial for 16 S rRNA 3' end maturation in V. cholerae and that its depletion impedes subunit assembly into 70 S ribosomes. YbeY's importance to V. cholerae pathogenesis was demonstrated by the complete loss of mice colonization and biofilm formation, reduced cholera toxin production, and altered expression levels of virulence-associated small RNAs of a V. cholerae strain partially depleted for YbeY. Notably, the ybeY genes of several distantly related pathogens can fully complement an E. coli ΔybeY strain under various stress conditions, demonstrating the high conservation of YbeY's activity in stress regulation. Taken together, this work provides the first comprehensive exploration of YbeY's physiological role in a human pathogen, showing its conserved function across species in essential cellular processes.
Purpose
Anterior cruciate ligament reconstruction (ACLR) aims to restore knee function and stability, allowing patients to return to the activities they enjoy and minimize further injury to the ...meniscus and cartilage and their ultimate progression to osteoarthritis. This study aims to present the evolution of graft choice over the last three decades according to members of the ACL Study Group (SG).
Methods
Prior to the January 2020 ACL SG biannual meeting, a survey was administered consisting of 87 questions and 16 categories, including ACLR graft choice. A similar questionnaire has been administered prior to each meeting and survey results from the past 14 meetings (1992 through 2020, excluding 1994) are included in this work. Survey responses are reported as frequencies in percentages to quantify changes in practice over the surgery period.
Results
In 1992, the most frequent graft choice for primary ACLR was bone-patellar tendon-bone (BTB) autograft, at nearly 90%. Hamstring tendon (HT) autografts have increased in popularity, currently over 50%, followed by just under 40% BTB autograft. Recently, quadriceps tendon (QT) autograft has increased in popularity since 2014.
Conclusion
Autograft (HT, BTB, QT) is an overwhelming favorite for primary ACLR over allograft. The preference for HT autograft increased over the study period relative to BTB autograft, with QT autograft gaining in popularity in recent years. Graft selection should be individualized for each patient and understanding the global trends in graft choice can help orthopaedic surgeons discuss graft options with their patients and determine the appropriate graft for each case.
Level of evidence
Level V, Expert Opinion.
enters into beneficial symbiotic interactions with
species of legumes. Bacterial exopolysaccharides play critical signaling roles in infection thread initiation and growth during the early stages of ...root nodule formation. After endocytosis of
by plant cells in the developing nodule, plant-derived nodule-specific cysteine-rich (NCR) peptides mediate terminal differentiation of the bacteria into nitrogen-fixing bacteroids. Previous transcriptional studies showed that the intensively studied cationic peptide NCR247 induces expression of the
genes that encode the proteins required for succinoglycan biosynthesis. In addition, genetic studies have shown that some
mutants exhibit increased sensitivity to the antimicrobial action of NCR247. Therefore, we investigated whether the symbiotically active
exopolysaccharide succinoglycan can protect
against the antimicrobial activity of NCR247. We discovered that high-molecular-weight forms of succinoglycan have the ability to protect
from the antimicrobial action of the NCR247 peptide but low-molecular-weight forms of wild-type succinoglycan do not. The protective function of high-molecular-weight succinoglycan occurs via direct molecular interactions between anionic succinoglycan and the cationic NCR247 peptide, but this interaction is not chiral. Taken together, our observations suggest that
exopolysaccharides not only may be critical during early stages of nodule invasion but also are upregulated at a late stage of symbiosis to protect bacteria against the bactericidal action of cationic NCR peptides. Our findings represent an important step forward in fully understanding the complete set of exopolysaccharide functions during legume symbiosis.
Symbiotic interactions between rhizobia and legumes are economically important for global food production. The legume symbiosis also is a major part of the global nitrogen cycle and is an ideal model system to study host-microbe interactions. Signaling between legumes and rhizobia is essential to establish symbiosis, and understanding these signals is a major goal in the field. Exopolysaccharides are important in the symbiotic context because they are essential signaling molecules during early-stage symbiosis. In this study, we provide evidence suggesting that the
exopolysaccharide succinoglycan also protects the bacteria against the antimicrobial action of essential late-stage symbiosis plant peptides.
This study investigates, via two experiments, the effects of target transparency, which reflects employees' knowledge about each other's targets in an organization, on managers' target setting ...decisions. We also investigate whether this effect depends on the need for help among employees. We predict and find that target transparency and need for help interact to influence managers' target setting decisions. Target transparency increases target levels when the need for help is low, but not when it is high. Further, target transparency leads managers to differentiate less between individual employee targets. This reduction is greater when the need for help is high than when it is low. Additional analyses support our theory by revealing that managers strategically set targets in a way that is consistent with an intention to motivate both effort at the individual level and help among employees when such are needed. Our results help explain anecdotal evidence of why companies that value help among employees often make targets transparent throughout the entire organization.
In a world characterized by increasing pressure from financial and product markets, the question of how exogenous constraints affect internal coordination and control processes has become ...increasingly important. This experiment investigates how two exogenous constraints that superiors can face in budget negotiation settings, increased opportunity costs and financial pressure to meet unit targets, affect budget negotiations and subordinate effort. The results show that both constraints induce more cooperation, but in different ways. Financial pressure on the superior leads to more cooperative negotiation behavior by superiors and subordinates than increased opportunity costs. Specifically, subordinates do not take advantage of the superior's increased financial pressure to enforce lower budgets. After negotiation, both constraints strongly mitigate the negative effects of superior budget imposition on subordinate effort because exogenous constraints eliminate the effect of procedural fairness considerations on subordinate effort.
Purpose
A subset of patients is usually not satisfied after a total knee arthroplasty (TKA). Customised individually made (CIM) TKA are deemed to overcome drawbacks of classical off-the-shelf (OTS) ...TKA, but evidence is still sparse. The aim of this study was to compare satisfaction of patients with CIM and OTS TKA.
Methods
This prospective cohort study compared clinical and patient-reported outcome measures (PROM) between patients with CIM and OTS TKA. The primary outcome was patient satisfaction after 12 months. Secondary outcomes were the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), the Forgotten Joint Score (FJS-12) and the EQ-5D-3L after 4 and 12 months.
Results
Data were analysed from 74 CIM TKA and 169 OTS TKA between January 2017 and September 2020. Patients with CIM TKA were slightly younger, more often male, had a lower body mass index, a lower KSS and partially higher preoperative PROMs.
Patient satisfaction after 12 months was high and comparable (CIM 87%, OTS 89%). All PROMs improved for both groups (
p
< 0.001) and did not differ after 12 months (
p
> 0.063). The majority of patients improved above the minimal important difference (range 65 to 89%) and reported a clear overall improvement (CIM 86%, OTS 87%). The postoperative KSS, notably regarding knee stability, was higher for CIM TKA (
p
< 0.001).
Conclusion
No difference was found in patient satisfaction between CIM and OTS TKA after 12 months. In both groups, patient satisfaction was high and PROMs improved considerably.
Level of evidence
II, prospective cohort study.
PDF
