Characterization of MtfA, a novel regulatory output signal protein of the glucose-phosphotransferase system in Escherichia coli K-12

The glucose-phosphotransferase system (PTS) in Escherichia coli K-12 is a complex sensory and regulatory system. In addition to its central role in glucose uptake, it informs other global regulatory networks about carbohydrate availability and the physiological status of the cell. The expression of the ptsG gene encoding the glucose-PTS transporter EIICB(Glc) is primarily regulated via the repressor Mlc, whose inactivation is glucose dependent. During transport of glucose and dephosphorylation of EIICB(Glc), Mlc binds to the B domain of the transporter, resulting in derepression of several Mlc-regulated genes. In addition, Mlc can also be inactivated by the cytoplasmic protein MtfA in a direct protein-protein interaction. In this study, we identified the binding site for Mlc in the carboxy-terminal region of MtfA by measuring the effect of mutated MtfAs on ptsG expression. In addition, we demonstrated the ability of MtfA to inactivate an Mlc super-repressor, which cannot be inactivated by EIICB(Glc), by using in vivo titration and gel shift assays. Finally, we characterized the proteolytic activity of purified MtfA by monitoring cleavage of amino 4-nitroanilide substrates and show Mlc's ability to enhance this activity. Based on our findings, we propose a model of MtfA as a glucose-regulated peptidase activated by cytoplasmic Mlc. Its activity may be necessary during the growth of cultures as they enter the stationary phase. This proteolytic activity of MtfA modulated by Mlc constitutes a newly identified PTS output signal that responds to changes in environmental conditions.     

DendroCT – Dendrochronology without damage

The paper describes an evaluation of the applicability of computer tomography in archaeological dendrochronology. Two different computer tomographs were tested, a Siemens Somatom Emotion single slice scanner developed for medical use, and a Nikon Metrology model XT H 225 LC, which is an industrial type scanner. Both scanners were tested against air-dried, archaeological oak wood, and more limited experiments were made with waterlogged archaeological oak wood and archaeological oak wood which had been treated with high-molecular polyethyleneglycol as a conservation treatment. After scanning the resulting imagery were measured and analysed for dendrochronology using off-the-shelf software for handling and measuring on the images and the specialist programme DENDRO for the dendrochronological analyses.The results showed that only the industrial scanner produced sufficiently clear imagery to allow for dendrochronological analyses. In the scans it was possible to separate tree-rings down to 0.2 mm width, and it was possible to identify the sapwood–heartwood border when sufficient sapwood rings were present. It was found, however, that a visual inspection of the object was required to distinguish between sapwood and decayed wood. Comparisons between direct measurements of tree-rings and measurements based on CT-imagery revealed no significant differences. The scanning and subsequent dating of more than 90 objects showed that dendrochronological dating based on CT-scanning has a success rate equal to conventional dating, albeit more time consuming.The attempts to scan waterlogged and PEG-impregnated archaeological oak wood were unsuccessful, due to a low degree of contrast between the water/PEG and the preserved wood. The experiments were too limited to exclude, however, that a successful protocol can be developed also for these types of materials.     

Effect of a High-Intensity Exercise Program on Physical Function and Mental Health in Nursing Home Residents with Dementia: An Assessor Blinded Randomized Controlled Trial

Background

Dementia is among the leading causes of functional loss and disability in older adults. Research has demonstrated that nursing home patients without dementia can improve their function in activities of daily living, strength, balance and mental well being by physical exercise. The evidence on effect of physical exercise among nursing home patients with dementia is scarce and ambiguous. Thus, the primary objective of this study was to investigate the effect of a high intensity functional exercise program on the performance of balance in nursing home residents with dementia. The secondary objective was to examine the effect of this exercise on muscle strength, mobility, activities of daily living, quality of life and neuropsychiatric symptoms.

Design and Methods

This single blinded randomized controlled trial was conducted among 170 persons with dementia living in nursing homes. Mean age was 86.7 years (SD = 7.4) and 74% were women. The participants were randomly allocated to an intervention (n = 87) or a control group (n = 83). The intervention consisted of intensive strengthening and balance exercises in small groups twice a week for 12 weeks. The control condition was leisure activities.

Results

The intervention group improved the score on Bergs Balance Scale by 2.9 points, which was significantly more than the control group who improved by 1.2 points (p = 0.02). Having exercised 12 times or more was significantly associated with improved strength after intervention (p<0.05). The level of apathy was lower in the exercise group after the intervention, compared to the control group (p = 0.048).

Conclusion

The results from our study indicate that a high intensity functional exercise program improved balance and muscle strength as well as reduced apathy in nursing home patients with dementia.

Trial Registration

ClinicalTrials.gov NCT02262104     

Quantitative trait loci affecting clinical mastitis and somatic cell count in dairy cattle

Norway has a field recording system for dairy cattle that includes recording of all veterinary treatments on an individual animal basis from 1978 onwards. Application of these data in a genome search for quantitative trait loci (QTL) verified genome-wise significant QTL affecting clinical mastitis on Chromosome (Chr) 6. Additional putative QTL for clinical mastitis were localized to Chrs. 3, 4, 14, and 27. The comprehensive field recording system includes information on somatic cell count as well. This trait is often used in selection against mastitis when direct information on clinical mastitis is not available. The absence of common QTL positions for the two traits in our study indicates that the use of somatic cell count data in QTL studies aimed for reducing the incidence of mastitis should be carefully evaluated. Received: 9 May 2001 / Accepted: 6 July 2001     

Unveiling an abundant core microbiota in the human adult colon by a phylogroup-independent searching approach

The potential presence of widespread and stable bacterial core phylogroups in the human colon has promoted considerable attention. Despite major efforts, no such phylogroups have yet been identified. Therefore, using a novel phylogroup- and tree-independent approach, we present a reanalysis of 1 114 722 V2 region and 71 550 near full-length 16S rRNA sequences from a total of 210 human beings, with widespread geographic origin, ethnic background and diet, in addition to a wide range of other mammals. We found two highly prevalent core phylogroups (cores 1 and 2), belonging to the clostridial family Lachnospiraceae. These core phylogroups showed a log-normal distribution among human individuals, while non-core phylogroups showed more skewed distributions towards individuals with low levels compared with the log-normal distribution. Molecular clock analyses suggest that core 2 co-evolved with the radiation of vertebrates, while core 1 co-evolved with the mammals. Taken together, the stability, prevalence and potential functionality support the fact that the identified core phylogroups are pivotal in maintaining gut homeostasis and health.     

Direct Haplotype‐Specific DNA Sequencing

Abstract

Determining haplotype‐specific DNA sequence information is very important in a wide range of research fields. However, no simple and robust approaches are currently available for determining haplotype‐specific sequence information. We have addressed this problem by developing a very simple and robust haplotype‐specific sequencing approach. We utilise the fact that DNA sequencing polymerases are sensitive to 3′end mismatches in the sequencing primer. By using two sequencing primers with 3′end corresponding to the two alleles in a given SNP locus, we are able to obtain allele‐specific DNA sequences from both alleles.

We evaluated this direct haplotype‐specific approach by determining haplotypes within the intron 2 sequence of the fructan‐6‐fructosyltransferase (6‐ft) gene in Lolium perenne L. We obtained reliable haplotype‐specific sequences for all primers and genotypes evaluated. We conclude that the haplotype‐specific sequencing is robust, and that the approach has a potentially very wide application range for any diploid organism.     

Secondary lymphoid tissue chemokine (CCL21) activates CXCR3 to trigger a Cl- current and chemotaxis in murine microglia

Microglial cells represent the major immunocompetent element of the CNS and are activated by any type of brain injury or disease. A candidate for signaling neuronal injury to microglial cells is the CC chemokine ligand CCL21, given that damaged neurons express CCL21. Investigating microglia in acute slices and in culture, we demonstrate that a local application of CCL21 for 30 s triggered a Cl(-) conductance with lasted for tens of minutes. This response was sensitive to the Cl(-) channel blockers 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid and 4-acetamide-4'-isothiocyanatostilbene, 2,2'-disulfonic acid. Moreover, CCL21 triggered a chemotaxis response, which was sensitive to Cl(-) channel blockers. In microglial cells cultured from CCR7 knockout mice, CCL21 produced the same type of Cl(-) current as well as a chemotaxis response. In contrast, in microglial cells from CXCR3 knockout mice, CCL21 triggered neither a Cl(-) conductance nor a chemotaxis response after CCL21 application. We conclude that the CCL21-induced Cl(-) current is a prerequisite for the chemotaxis response mediated by the activation of CXCR3 but not CCR7 receptors, indicating that in brain CCL21 acts via a different receptor system than in lymphoid organs.     

Root growth plasticity to drought in seedlings of perennial grasses

Plant and Soil - Root growth strategies may be critical for seeding survival and establishment under dry conditions, but these strategies and their plasticity are little known. We aim to document...     

Multiple paternity in Ixodes ricinus (Acari: Ixodidae), assessed by microsatellite markers

This investigation examines multiple paternity in Ixodes ricinus (Acari: Ixodidae). Previous studies have shown that multiple mating occurs in this tick, but this is the first evaluation of multiple paternity. Three family groups were examined by a panel of polymorphic microsatellite loci; all ticks were bred from wild-collected engorged females with a copulating male attached. For most larvae, the attached males could be excluded as possible sire, and in the 3 tested families, at least 2 of 3 females mated successfully with more than 1 male. This finding suggests that multiple paternity is a common reproductive strategy in I. ricinus, which may have consequences for the ticks' dispersal success by increasing the genetic diversity in broods from single females colonizing new sites.