In vitro synthesis and repression of argininosuccinase in Escherichia coli K12; partial purification of the arginine repressor

Summary 80dargECBH DNA has been used to direct cell-free synthesis of argininosuccinase, the argH gene product in Escherichia coli K12. In vitro enzyme synthesis is sensitive to repression by partially purified preparations from an argR ⁺ strain but not by corresponding preparations from an argR ^- strain. Using DNA-cellulose chromatography, approximately seventyfold purification of repressor has been obtained. The partially purified preparation represses argininosuccinase synthesis but has no effect on -galactosidase synthesis.     

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.

     

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.

     

Reexamination of the Species Assignment of Diacavolinia Pteropods Using DNA Barcoding

Thecosome pteropods (Mollusca, Gastropoda) are an ecologically important, diverse, and ubiquitous group of holoplanktonic animals that are the focus of intense research interest due to their external aragonite shell and vulnerability to ocean acidification. Characterizing the response of these animals to low pH and other environmental stressors has been hampered by continued uncertainty in their taxonomic identification. An example of this confusion in species assignment is found in the genus Diacavolinia. All members of this genus were originally indentified as a single species, Cavolinia longirostris, but over the past fifty years the taxonomy has been revisited multiple times; currently the genus comprises 22 different species. This study examines five species of Diacavolinia, including four sampled in the Northeast Atlantic (78 individuals) and one from the Eastern tropical North Pacific (15 individuals). Diacavolina were identified to species based on morphological characteristics according to the current taxonomy, photographed, and then used to determine the sequence of the “DNA barcoding” region of the cytochrome c oxidase subunit I (COI). Specimens from the Atlantic, despite distinct differences in shell morphology, showed polyphyly and a genetic divergence of <3% (K2P distance) whereas the Pacific and Atlantic samples were more distant (∼19%). Comparisons of Diacavolinia spp. with other Cavolinia spp. reveal larger distances (∼24%). These results indicate that specimens from the Atlantic comprise a single monophyletic species and suggest possible species-level divergence between Atlantic and Pacific populations. The findings support the maintenance of Diacavolinia as a separate genus, yet emphasize the inadequacy of our current taxonomic understanding of pteropods. They highlight the need for accurate species identifications to support estimates of biodiversity, range extent and natural exposure of these planktonic calcifiers to environmental variability; furthermore, the apparent variation of the pteropods shell may have implications for our understanding of the species’ sensitivity to ocean acidification.     

Long-term effects of timber harvesting on hemicellulolytic microbial populations in coniferous forest soils

Forest ecosystems need to be sustainably managed, as they are major reservoirs of biodiversity, provide important economic resources and modulate global climate. We have a poor knowledge of populations responsible for key biomass degradation processes in forest soils and the effects of forest harvesting on these populations. Here, we investigated the effects of three timber-harvesting methods, varying in the degree of organic matter removal, on putatively hemicellulolytic bacterial and fungal populations 10 or more years after harvesting and replanting. We used stable-isotope probing to identify populations that incorporated ¹³C from labeled hemicellulose, analyzing ¹³C-enriched phospholipid fatty acids, bacterial 16 S rRNA genes and fungal ITS regions. In soil microcosms, we identified 104 bacterial and 52 fungal hemicellulolytic operational taxonomic units (OTUs). Several of these OTUs are affiliated with taxa not previously reported to degrade hemicellulose, including the bacterial genera Methylibium, Pelomonas and Rhodoferax, and the fungal genera Cladosporium, Pseudeurotiaceae, Capronia, Xenopolyscytalum and Venturia. The effect of harvesting on hemicellulolytic populations was evaluated based on in situ bacterial and fungal OTUs. Harvesting treatments had significant but modest long-term effects on relative abundances of hemicellulolytic populations, which differed in strength between two ecozones and between soil layers. For soils incubated in microcosms, prior harvesting treatments did not affect the rate of incorporation of hemicellulose carbon into microbial biomass. In six ecozones across North America, distributions of the bacterial hemicellulolytic OTUs were similar, whereas distributions of fungal ones differed. Our work demonstrates that diverse taxa in soil are hemicellulolytic, many of which are differentially affected by the impact of harvesting on environmental conditions. However, the hemicellulolytic capacity of soil communities appears resilient.     

Diagnosis of takotsubo cardiomyopathy is increasing over time in patients presenting as ST-elevation myocardial infarction

Background

Takotsubo cardiomyopathy often presents with the clinical signs of ST-elevation myocardial infarction (STEMI). The increase in scientific publications addressing this relatively rare condition may result in higher awareness and diagnosis of takotsubo cardiomyopathy.

Aim

To assess the observed prevalence per year of takotsubo cardiomyopathy in a large registry of patients with STEMI, during a 12-year inclusion period.

Method

All patients presenting with STEMI at a large regional cardiology clinic were entered into a database (n = 8,413, mean age 63 ± 13 years). Takotsubo cardiomyopathy was diagnosed in 42 patients (0.5?%). Years of evaluation were defined as ‘early years’ (January 2002 to December 2007; n = 4350) and ‘later years’ (January 2008 to December 2013). Multivariable analyses were performed to adjust for differences in demographical and clinical variables.

Results

In later years, the age of STEMI patients was slightly higher (64 ± 13 vs. 63 ± 13 years, p < 0.001), with more patients with clinical symptoms of shock (10 vs. 7?%, p < 0.001) or a history of percutaneous coronary intervention or hypertension (10 vs. 8?%, p = 0.001 and 37 vs. 34?%, p < 0.001). Smoking and a positive family history were less often observed during later years (39 vs. 46?%, p < 0.001 and 37 vs. 42?% p < 0.001). Patients with takotsubo cardiomyopathy were more often female (81 vs. 27?%, p = 0.001). Takotsubo cardiomyopathy was more often diagnosed in the later period (0.7 vs. 0.3?%, OR 2.4, 95?% CI 1.2–4.6, p = 0.009). The higher prevalence of takotsubo cardiomyopathy in recent years remained significant after adjustment for differences in patient characteristics (OR 2.1, 95?% CI 1.1–4.3).

Conclusion

Takotsubo cardiomyopathy is currently more often diagnosed in patients with STEMI compared with in earlier years. This is probably due to the increased scientific and clinical awareness among doctors, but the prevalence is still low.

     

Archaic and contemporary topographic diversification of Upper Mississippi River forests

Topographic diversity is an important component of environmental heterogeneity. Topographic diversity within the Upper Mississippi River floodplain has been degraded because of modifications for navigation improvement. Efforts aimed at restoring topographic diversity in the Upper Mississippi River floodplain have been extensive but have not focused on reversing the effects of forest loss and degradation. We investigated habitat features associated with Cerulean Warbler (Setophaga cerulea) locations both within and outside of river floodplains and hypothesized this species would select topographically diverse habitats. Both topographic diversity and the distance to the upland forest/floodplain forest interface were useful predictors of Cerulean Warbler presence. We conclude that incorporation of topographic diversity into floodplain forest restoration planning would likely benefit Cerulean Warblers and the other species with similar habitat requirements. Incorporating topographic diversity into floodplain forest conservation planning will be challenging on major rivers that serve multiple purposes.