Expression of a mutation affecting F incompatibility in the integrated but not the autonomous state of F.

Previously we have described a mutant Hfr strain in which incompatibility between the integrated F factor and an autonomous F-prime (F') factor was abolished. The mutation (inc) was located in the integrated F factor. F-prime factors isolated from the mutant Hfr strain have the same incompatibility behavior as those isolated from normal Hfr strains. Reintegration of these F' factors into the chromosome restores the Inc- phenotype characteristic of the mutant Hfr. The inc mutation thus affects incompatibility between integrated F and autonomous F(Fi-Fa incompatibility) but not incompatibility between two autonomous F factors (Fa-Fa incompatibility). The implications of this finding for the mechanism of plasmid incompatibility are discussed.     

Ant community composition and functional traits in new grassland strips within agricultural landscapes

1. Ongoing intensification and fragmentation of European agricultural landscapes dramatically reduce biodiversity and associated functions. Enhancing perennial noncrop areas holds great potential to support ecosystem services such as ant‐mediated pest control.
2. To study the potential of newly established grassland strips to enhance ant diversity and associated functions, we used hand collection data and predation experiments to investigate differences in (a) ant community composition and (b) biocontrol‐related functional traits, and (c) natural pest control across habitats in cereal fields, old grasslands, and new grassland transects of three years of age.
3. Ant species diversity was similar between new and old grasslands, but significantly higher in new grasslands than in surrounding cereal fields. Contrary, ant community composition of new grasslands was more similar to cereal fields and distinct from the species pool of old grasslands. The functional trait space covered by the ant communities showed the same distribution between old and new grasslands. Pest control did not differ significantly between habitat types and therefore could not be linked to the prevalence of functional ant traits related to biocontrol services in new grasslands.
4. Our findings not only show trends of convergence between old and new grasslands, but also indicate that enhancing ant diversity through new grasslands takes longer than three years to provide comparable biodiversity and functionality.
5. Synthesis and applications: Newly established grasslands can increase ant species richness and abundance and provide a consistent amount of biocontrol services in agroecosystems. However, three years after their establishment, new grasslands were still dominated by common agrobiont ant species and lacked habitat specialists present in old grasslands, which require a constant supply of food resources and long colony establishment times. New grasslands represent a promising measure for enhancing agricultural landscapes but must be preserved in the longer term to promote biodiversity and resilience of associated ecosystem services.

     

Food availability affects the strength of mutualistic host–microbiota interactions in Daphnia magna

The symbiotic gut microbial community is generally known to have a strong impact on the fitness of its host. Nevertheless, it is less clear how the impact of symbiotic interactions on the hosts'' fitness varies according to environmental circumstances such as changes in the diet. This study aims to get a better understanding of host–microbiota interactions under different levels of food availability. We conducted experiments with the invertebrate, experimental model organism Daphnia magna and compared growth, survival and reproduction of conventionalized symbiotic Daphnia with germ-free individuals given varying quantities of food. Our experiments revealed that the relative importance of the microbiota for the hosts'' fitness varied according to dietary conditions. The presence of the microbiota had strong positive effects on Daphnia when food was sufficient or abundant, but had weaker effects under food limitation. Our results indicate that the microbiota can be a potentially important factor in determining host responses to changes in dietary conditions. Characterization of the host-associated microbiota further showed that Aeromonas sp. was the most prevalent taxon in the digestive tract of Daphnia.     

Psychological and clinical characteristics of female patients with spontaneous coronary artery dissection

Aims

Spontaneous coronary artery dissection (SCAD) is increasingly recognised as a cause of myocardial infarction, but psychological characteristics of patients with SCAD have not yet been extensively investigated. We assessed the prevalence of a broad range of psychological and clinical factors, and their inter-relationships in patients with a history of SCAD. Furthermore, we investigated whether specific clusters of patients with SCAD can be identified.

Methods

Participants were recruited between March and May 2019 from a Dutch SCAD database and completed online questionnaires. Clinical information was verified by review of medical records. Participants were predominantly female (172/183; 94%). Analyses focused on the 172 female patients (mean age 52.0 ± 7.5 years, 37% postmenopausal).

Results

The most common comorbidities of SCAD were migraine (52%), fibromuscular dysplasia (FMD; 29%), chronic pain (29%), and tinnitus (28%). Six women (3%) had pregnancy-associated SCAD. Traditional cardiovascular risk factors were rare (<10%), except for hypertension (31%). Psychological assessment indicated high levels of perceived stress (PSS-10 ≥14; 50%), fatigue (FAS-10 ≥22; 56%), and a frequent history of burnout (25%). The prevalence of depression (9%) and anxiety (12%) was relatively low. Three clusters were identified: (A) FMD and chronic non-ischaemic conditions (tinnitus, chronic pain, and irritable bowel syndrome); (B) migraine; and (C) none of these conditions.

Conclusion

This study shows that perceived stress and fatigue are common in patients with SCAD, in addition to prevalent comorbid FMD, migraine, tinnitus, and non-ischaemic pain conditions. These factors may add to developing tailored rehabilitation programmes for patients with SCAD.

     

Different effects of carbohydrate binding modules on the viscoelasticity of nanocellulose gels

Many cellulose degrading and modifying enzymes have distinct parts called carbohydrate binding modules (CBMs). The CBMs have been shown to increase the concentration of enzymes on the insoluble substrate and thereby enhance catalytic activity. It has been suggested that CBMs also have a role in disrupting or dispersing the insoluble cellulose substrate, but dispute remains and explicit evidence of such a mechanism is lacking. We produced the isolated CBMs from two major cellulases (Cel6A and Cel7A) from Trichoderma reesei as recombinant proteins in Escherichia coli. We then studied the viscoelastic properties of native unmodified cellulose nanofibrils (CNF) in combination with the highly purified CBMs to detect possible functional effects of the CBMs on the CNF. The two CBMs showed clearly different effects on the viscoelastic properties of CNF. The difference in effects is noteworthy, yet it was not possible to conclude for example disruptive effects. We discuss here the alternative explanations for viscoelastic effects on CNF caused by CBMs, including the effect of ionic cosolutes.     

Richness and abundance of stream fish communities in a fragmented neotropical landscape

Environmental Biology of Fishes - Environmental conditions influence ecological processes that shape stream community diversity and abundance. Deforestation has the potential to limit available...     

mTORC1 activity is supported by spatial association with focal adhesions

The mammalian target of rapamycin complex 1 (mTORC1) integrates mitogenic and stress signals to control growth and metabolism. Activation of mTORC1 by amino acids and growth factors involves recruitment of the complex to the lysosomal membrane and is further supported by lysosome distribution to the cell periphery. Here, we show that translocation of lysosomes toward the cell periphery brings mTORC1 into proximity with focal adhesions (FAs). We demonstrate that FAs constitute discrete plasma membrane hubs mediating growth factor signaling and amino acid input into the cell. FAs, as well as the translocation of lysosome-bound mTORC1 to their vicinity, contribute to both peripheral and intracellular mTORC1 activity. Conversely, lysosomal distribution to the cell periphery is dispensable for the activation of mTORC1 constitutively targeted to FAs. This study advances our understanding of spatial mTORC1 regulation by demonstrating that the localization of mTORC1 to FAs is both necessary and sufficient for its activation by growth-promoting stimuli.