Rhizosheath drought responsiveness is variety-specific and a key component of belowground plant adaptation

Biophysicochemical rhizosheath properties play a vital role in plant drought adaptation. However, their integration into the framework of plant drought response is hampered by incomplete mechanistic understanding of their drought responsiveness and unknown linkage to intraspecific plant-soil drought reactions. Thirty-eight Zea mays varieties were grown under well-watered and drought conditions to assess the drought responsiveness of rhizosheath properties, such as soil aggregation, rhizosheath mass, net-rhizodeposition, and soil organic carbon distribution. Additionally, explanatory traits, including functional plant trait adaptations and changes in soil enzyme activities, were measured. Drought restricted soil structure formation in the rhizosheath and shifted plant-carbon from litter-derived organic matter in macroaggregates to microbially processed compounds in microaggregates. Variety-specific functional trait modifications determined variations in rhizosheath drought responsiveness. Drought responses of the plant-soil system ranged among varieties from maintaining plant-microbial interactions in the rhizosheath through accumulation of rhizodeposits, to preserving rhizosheath soil structure while increasing soil exploration through enhanced root elongation. Drought-induced alterations at the root-soil interface may hold crucial implications for ecosystem resilience in a changing climate. Our findings highlight that rhizosheath soil properties are an intrinsic component of plant drought response, emphasizing the need for a holistic concept of plant-soil systems in future research on plant drought adaptation.

Unraveling root and rhizosphere traits in temperate maize landraces and modern cultivars: Implications for soil resource acquisition and drought adaptation

A holistic understanding of plant strategies to acquire soil resources is pivotal in achieving sustainable food security. However, we lack knowledge about variety-specific root and rhizosphere traits for resource acquisition, their plasticity and adaptation to drought. We conducted a greenhouse experiment to phenotype root and rhizosphere traits (mean root diameter [Root D], specific root length [SRL], root tissue density, root nitrogen content, specific rhizosheath mass [SRM], arbuscular mycorrhizal fungi [AMF] colonization) of 16 landraces and 22 modern cultivars of temperate maize (Zea mays L.). Our results demonstrate that landraces and modern cultivars diverge in their root and rhizosphere traits. Although landraces follow a 'do-it-yourself' strategy with high SRLs, modern cultivars exhibit an 'outsourcing' strategy with increased mean Root Ds and a tendency towards increased root colonization by AMF. We further identified that SRM indicates an 'outsourcing' strategy. Additionally, landraces were more drought-responsive compared to modern cultivars based on multitrait response indices. We suggest that breeding leads to distinct resource acquisition strategies between temperate maize varieties. Future breeding efforts should increasingly target root and rhizosphere economics, with SRM serving as a valuable proxy for identifying varieties employing an outsourcing resource acquisition strategy.

Transpiration response to soil drying versus increasing vapor pressure deficit in crops: physical and physiological mechanisms and key plant traits

The water deficit experienced by crops is a function of atmospheric water demand (vapor pressure deficit) and soil water supply over the whole crop cycle. We summarize typical transpiration response patterns to soil and atmospheric drying and the sensitivity to plant hydraulic traits. We explain the transpiration response patterns using a soil-plant hydraulic framework. In both cases of drying, stomatal closure is triggered by limitations in soil-plant hydraulic conductance. However, traits impacting the transpiration response differ between the two drying processes and act at different time scales. A low plant hydraulic conductance triggers an earlier restriction in transpiration during increasing vapor pressure deficit. During soil drying, the impact of the plant hydraulic conductance is less obvious. It is rather a decrease in the belowground hydraulic conductance (related to soil hydraulic properties and root length density) that is involved in transpiration down-regulation. The transpiration response to increasing vapor pressure deficit has a daily time scale. In the case of soil drying, it acts on a seasonal scale. Varieties that are conservative in water use on a daily scale may not be conservative over longer time scales (e.g. during soil drying). This potential independence of strategies needs to be considered in environment-specific breeding for yield-based drought tolerance.

Above and belowground traits impacting transpiration decline during soil drying in 48 maize (Zea mays) genotypes

BACKGROUND AND AIMS

Stomatal regulation allows plants to promptly respond to water stress. However, our understanding of the impact of above and belowground hydraulic traits on stomatal regulation remains incomplete. The objective of this study was to investigate how key plant hydraulic traits impact transpiration of maize during soil drying. We hypothesize that the stomatal response to soil drying is related to a loss in soil hydraulic conductivity at the root-soil interface, which in turn depends on plant hydraulic traits.

METHODS

We investigate the response of 48 contrasting maize (Zea mays) genotypes to soil drying, utilizing a novel phenotyping facility. In this context, we measure the relationship between leaf water potential, soil water potential, soil water content and transpiration, as well as root, rhizosphere and aboveground plant traits.

KEY RESULTS

Genotypes differed in their responsiveness to soil drying. The critical soil water potential at which plants started decreasing transpiration was related to a combination of above and belowground traits: genotypes with a higher maximum transpiration and plant hydraulic conductance as well as a smaller root and rhizosphere system closed stomata at less negative soil water potentials.

CONCLUSIONS

Our results demonstrate the importance of belowground hydraulics for stomatal regulation and hence drought responsiveness during soil drying. Furthermore, this finding supports the hypothesis that stomata start to close when soil hydraulic conductivity drops at the root-soil interface.

Bilateral filtering using the full noise covariance matrix applied to x-ray phase-contrast computed tomography

The purpose of this work is to develop an image-based de-noising algorithm that exploits complementary information and noise statistics from multi-modal images, as they emerge in x-ray tomography techniques, for instance grating-based phase-contrast CT and spectral CT. Among the noise reduction methods, image-based de-noising is one popular approach and the so-called bilateral filter is a well known algorithm for edge-preserving filtering. We developed a generalization of the bilateral filter for the case where the imaging system provides two or more perfectly aligned images. The proposed generalization is statistically motivated and takes the full second order noise statistics of these images into account. In particular, it includes a noise correlation between the images and spatial noise correlation within the same image. The novel generalized three-dimensional bilateral filter is applied to the attenuation and phase images created with filtered backprojection reconstructions from grating-based phase-contrast tomography. In comparison to established bilateral filters, we obtain improved noise reduction and at the same time a better preservation of edges in the images on the examples of a simulated soft-tissue phantom, a human cerebellum and a human artery sample. The applied full noise covariance is determined via cross-correlation of the image noise. The filter results yield an improved feature recovery based on enhanced noise suppression and edge preservation as shown here on the example of attenuation and phase images captured with grating-based phase-contrast computed tomography. This is supported by quantitative image analysis. Without being bound to phase-contrast imaging, this generalized filter is applicable to any kind of noise-afflicted image data with or without noise correlation. Therefore, it can be utilized in various imaging applications and fields.

Procalcitonin (PCT)-guided algorithm reduces length of antibiotic treatment in surgical intensive care patients with severe sepsis: results of a prospective randomized study

BACKGROUND

Adequate indication and duration of administration are central issues of modern antibiotic treatment in intensive care medicine. The biochemical variable procalcitonin (PCT) is known to indicate systemically relevant bacterial infections with high accuracy. In the present study, we aimed to investigate the clinical usefulness of PCT for guiding antibiotic treatment in surgical intensive care patients with severe sepsis.

PATIENTS AND METHODS

Patients were randomly assigned to a PCT-guided or a control group requiring antibiotic treatment. All patients received a calculated antibiotic regimen according to the presumed microbiological spectrum. In the PCT-guided group, antibiotic treatment was discontinued if clinical signs of infection improved and the PCT value was either <1 ng/ml or decreased to <35% of the initial concentration within three consecutive days. In the control group, antibiotic treatment was directed by empirical rules.

RESULTS

The PCT-guided group (n = 14 patients) and the control group (n = 13 patients) did not differ in terms of biological variables, underlying diseases, and overall disease severity. PCT guidance led to a significant reduction of antibiotic treatment from 6.6 +/- 1.1 days (mean +/- SD) compared with 8.3 +/- 0.7 days in control patients (p < 0.001) along with a reduction of antibiotic treatment costs of 17.8% (p < 0.01) without any adverse effects on outcome.

CONCLUSIONS

Monitoring of PCT is a helpful tool for guiding antibiotic treatment in surgical intensive care patients with severe sepsis. This may contribute to an optimized antibiotic regimen with beneficial effects on microbial resistances and costs in intensive care medicine.

Motion-compensated iterative cone-beam CT image reconstruction with adapted blobs as basis functions

This paper presents a three-dimensional method to reconstruct moving objects from cone-beam X-ray projections using an iterative reconstruction algorithm and a given motion vector field. For the image representation, adapted blobs are used, which can be implemented efficiently as basis functions. Iterative reconstruction requires the calculation of line integrals (forward projections) through the image volume, which are compared with the actual measurements to update the image volume. In the existence of a divergent motion vector field, a change in the volumes of the blobs has to be taken into account in the forward and backprojections. An efficient method to calculate the line integral through the adapted blobs is proposed. It solves the problem, how to compensate for the divergence in the motion vector field on a grid of basis functions. The method is evaluated on two phantoms, which are subject to three different known motions. Moreover, a motion-compensated filtered back-projection reconstruction method is used, and the reconstructed images are compared. Using the correct motion vector field with the iterative motion-compensated reconstruction, sharp images are obtained, with a quality that is significantly better than gated reconstructions.

Alcohol dehydrogenase 1B (ADH1B) genotype, alcohol consumption and breast cancer risk by age 50 years in a German case-control study

In a population-based study of 613 cases and 1082 controls, alcohol dehydrogenase 1B (ADH1B) genotype was not an independent risk factor for breast cancer, athough the possibility was raised that it modifies risk associated with high levels of alcohol consumption (OR 1.1, 95% confidence interval (CI) 0.8–1.6 for ADH1B*1/*1 genotype vs 0.2, 95% CI 0.1–1.0 for ADH1B*2 carriers).

mdm2 mRNA level is a prognostic factor in soft tissue sarcoma

BACKGROUND

The oncogenic properties of murine double minute-2 (mdm2) protein over-expression, which mostly results from the interaction with the tumor suppressor p53, are well described and their negative impacts on the prognosis of affected patients is well characterized. However, clinical relevance of mdm2 mRNA expression is poorly investigated.

MATERIALS AND METHODS

In this study, 65 soft tissue sarcoma (STS) samples were analyzed for mdm2 mRNA expression by a quantitative reverse transcription polymerase chain reaction (RT-PCR) approach using available validated ready-to-use assays based on the TaqMan technology (PE Applied Biosystems, Weiterstadt, Germany). Mdm2 data were correlated to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression calculated from the same sample.

RESULTS

For patients with a mdm2/GAPDH mRNA ratio below 50 zmol/amol the survival was strikingly reduced in comparison to patients with a ratio of > or =50 (p = 0.0241). Multivariate Cox analysis showed that the difference in prognosis for patients with tumor stage 2 and 3 became even more pronounced between patients with a ratio of <50 zmol/amol and patients with a ratio of > or =50 (p = 0.0041; RR = 5.6). To test if the group with an mdm2 mRNA expression > or =50 is homogenous concerning the prognosis, the group was divided into three subgroups with values of 50 to <100, 100 to <500 and > or =500. The subgroup with values of 100 to <500 showed the best prognosis (p = 0.0164); whereas, the one with values of 50 to <100 showed the worst prognosis in this group and, in between, was the one with values of > or =500. After omitting patients of stage 1 and 4, the subgroup with values of 100 to <500 showed an even more striking best prognosis (p = 0.0015); the other subgroups remained in the same sequence. The risk of tumor-related death over 5 years was most conspicuous in patients with mdm2 mRNA expression <50 than in those with ratios of 100 to <500 displaying a 13.3-fold higher risk. In a comparison between mdm2 mRNA levels and P53 protein expression or p53 mutational status, no relationship was found.

CONCLUSIONS

In our study, the mdm2 mRNA level appears to be an independent prognostic factor for STS patients, marking its role in STS genesis and as a potential factor for gene therapeutical approaches.

Sequence, assembly and analysis of pX01 and pX02

Bacillus anthracis plasmids pX01 and pX02, harboured by the Sterne and Pasteur strains, respectively, have been sequenced by random 'shotgun' cloning and high throughout sequence analysis. These sequences have been assembled (Sequencher) to generate a circulate pX01 plasmid containing 181 656 bp and a single linear (gapped) pX02 contig containing at least 93.479 bp. Initial annotation suggests that the two plasmids combined contain at least 200 potential open reading frames (ORFs) with < 40% having significant similarity to sequences registered in open databases. Collectively, only 118 566 bp of the pX01 DNA (65%) represent predicted coding regions. This value is similar to published gene densities for other plasmids and is indicative of the larger intergenic spaces in plasmids vs those found in the chromosomes of the parental microbes (85-93% gene density). A 70 kbp region including the toxin genes (cya, lef and pag) is distinct from the remainder of the pX01 sequence: (1) it has a lower gene density (58 vs 70%) than the remaining 111 kbp; (2) it contains all but one of the co-regulated transcriptional fusions identified by transposon mutagenesis (Hoffmaster & Koehler 1997) and (3) it contains a significantly higher proportion of positive BLAST scores (62 vs 20%) for putative ORFs. These data suggest different origins for the two regions of pX01.

Psychophysiological reactions of patients with atopic dermatitis

In a laboratory experiment, 20 female patients with atopic dermatitis (AD) and 20 female controls were exposed to two stress situations (watching a film about scarifications and tatooing, mental arithmetic). Recordings were made of systolic blood pressure, diastolic blood pressure, heart rate, skin conductance level (SCL), number of spontaneous (non-specific) electrodermal fluctuations (SF) and the PSI, the number of active palmar sweat glands in an area of the finger pad. Neither in the cardiovascular variables nor the PSI were any significant group differences found, neither for baseline nor stress values, nor for the response reactions. Atopic dermatitis persons had significantly lower values for SCL and SF throughout the whole experiment, although response reactions did not differ between groups. This study lends no support to the assumption of a general psychophysiological overreactivity or individual specific reactions of the skin system in patients with AD.

Frequency of migraine among an unselected group of employees and variation of prevalence according to different diagnostic criteria

A survey was carried out among 940 employees in a mail administration building in Hamburg, Germany to determine the prevalence rates of headache and of migraine, based on several definitions. Headache symptoms were assessed by means of questionnaires, which were returned by 92% of the addressed persons and properly evaluable in 87.8%. When 3 out of the following 4 criteria a) occurrence of headaches in attacks b) unilaterality of pain c) preceding visual disturbances d) pulsating character were required to diagnose migraine, prevalence rate was low (5.3%). It rose dramatically when only 2 of these requirements had to be met (18.0%); based on the definition that 2 of a), b) or c) had to be fulfilled, the prevalence rates were 13.1% for females, 5.6% for males. There was no difference in frequency of migraine between the two large income classes of mail employees. In accordance with other studies we found that only 57.5% of migraine patients had ever consulted a doctor for their headache; only 13.7% had done so within the last half year.

Headache syndromes as detected by configural frequency analysis

Data on headache symptoms obtained in two samples (N = 422 and 304) by means of questionnaires were subjected to configural frequency analysis (CFA). This not widely-known method tests whether certain symptom combinations appear more often or less often than expected by chance. In both samples symptom combinations corresponding to the syndromes of migraine with aura, migraine without aura and tension headache did indeed occur with significant frequency. The same clear-cut symptom patterns appeared when patients with preceding visual disturbances were excluded from analysis. These results seem to lend strong support to a categorical model of headache, rather than to the concept of headache as a spectrum.

Interpreting palmar sweat prints

The plastic impression method to assess the number of active palmar sweat glands (PSI) was used to study changes of sweat gland activity during several phases of dental treatment. Subjects were 64 female and 38 male patients at a dental surgery. At the beginning they scaled five typical dental situations in terms of perceived threat: waiting-room before treatment: sitting down in the dental chair; dentist enters and starts treatment; after treatment in the dental chair; and back in waiting-room after treatment. Four prints were taken in the waiting-room before treatment and one in each other situation described above. The average of prints 3 and 4 was used for phase comparisons. Palmar sweat index values were generally in accordance with the threat of the situations. In particular there was a rise from waiting-room to sitting down in the dental chair and a further increase at the dentist's entry, whereafter values dropped considerably. A significant decrease from the first two waiting-room values to the following two suggests that the PSI reacts sensitively to the novelty of the assessment procedure itself and that the very first recordings should hence not be taken into evaluation.

Stress and rheumatoid arthritis: a survey of empirical evidence in human and animal studies

Literature concerning rheumatoid arthritis (RA) was reviewed with regard to the empirical evidence for the widely held view that the onset and course of the disease are influenced by stress variables. Human studies yielded contradictory results; there are at least two large well-controlled investigations that were not able to find a preponderance of life stress variables prior to the onset of the disease in RA patients compared to other patients or healthy subjects. Findings of animal studies are inconsistent, too: Some kinds of stress seem to abrogate, whereas others may rather enhance the development of rheumatic symptoms. Possible pathogenetic models are discussed to explain the influence of stress on the disease. For further research, the use of more sophisticated methods to assess life events, and prospective longitudinal studies in RA patients are suggested to find out whether stressful events antedate relapses. Such correlations should be examined for patients with seronegative and seropositive RA separately.