Key message
We identified two poplar clones of the same species as highly comparable, yet clones of two further species of the same genus to be distinctly different regarding multiple morphological ...and ecophysiological traits.
Leaf morphology, wax composition, and residual (cuticular) transpiration of four poplar clones (two clones of the hybrid species
P.
×
canescens
,
P. trichocarpa
, and
P. euphratica
) were monitored from the beginning to end of the growing season 2020. A pronounced epicuticular wax coverage was found only with
P. euphratica
. As the most prominent substance classes of cuticular wax primary alcohols, alkanes and esters were identified with
P.
×
canescens
and
P. trichocarpa
, whereas esters and alkanes were completely lacking in
P. euphratica
. Wax amounts were slightly decreasing during the season and significantly lower wax amounts were found for newly formed leaves in summer compared to leaves of the same age formed in spring. Residual (cuticular) transpiration was about five to tenfold lower for
P.
×
canescens
compared with the two other poplar species. Interestingly, with three of the four investigated species, newly formed leaves in summer had lower wax coverages and lower rates of residual (cuticular) transpiration compared to leaves of exactly the same age formed in spring. Our findings were especially surprising with
P. euphratica
, representing the only one of the four investigated poplar species naturally growing in very dry and hot climates in Central Asia. Instead of developing very low rates of residual (cuticular) transpiration, it seems to be of major advantage for
P. euphratica
to develop a pronounced epicuticular wax bloom efficiently reflecting light.
Populus
is an important tree genus frequently cultivated for economical purposes. However, the high sensitivity of poplars towards water deficit, drought, and salt accumulation significantly affects ...plant productivity and limits biomass yield. Various cultivation and abiotic stress conditions have been described to significantly induce the formation of apoplastic barriers (Casparian bands and suberin lamellae) in roots of different monocotyledonous crop species. Thus, this study aimed to investigate to which degree the roots of the dicotyledonous gray poplar (
Populus
×
canescens
) react to a set of selected cultivation conditions (hydroponics, aeroponics, or soil) and abiotic stress treatments (abscisic acid, oxygen deficiency) because a differing stress response could potentially help in explaining the observed higher stress susceptibility. The apoplastic barriers of poplar roots cultivated in different environments were analyzed by means of histochemistry and gas chromatography and compared to the available literature on monocotyledonous crop species. Overall, dicotyledonous poplar roots showed only a remarkably low induction or enhancement of apoplastic barriers in response to the different cultivation conditions and abiotic stress treatments. The genetic optimization (e.g., overexpression of biosynthesis key genes) of the apoplastic barrier development in poplar roots might result in more stress-tolerant cultivars in the future.
The effect of contrasting environmental growth conditions (in vitro tissue culture, ex vitro acclimatisation, climate chamber, greenhouse and outdoor) on leaf development, cuticular wax composition, ...and foliar transpiration of detached leaves of the Populus × canescens clone 84 K were investigated. Our results show that total amounts of cuticular wax increased more than 10‐fold when cultivated in different growth conditions, whereas qualitative wax composition did not change. With exception of plants directly taken from tissue culture showing rapid dehydration, rates of water loss (residual foliar transpiration) of intact but detached leaves were constant and independent from growth conditions and thus independent from increasing wax amounts. Since cuticular transpiration measured with isolated astomatous P. × canescens cuticles was identical to residual foliar transpiration rates of detached leaves, our results confirm that cuticular transpiration of P. × canescens leaves can be predicted with high accuracy from residual transpiration of detached leaves after stomatal closure. Our results convincingly show that more than 10‐fold increased wax amounts in P. × canescens cuticles do not lead to decreased rates of residual (cuticular) transpiration.
This study focuses on the role of the qualitative leaf wax composition in modulating the cuticular water loss using a Populus × canescens cer6 mutant line, which accumulates C34–C46 wax ester dimers ...and is reduced in wax monomers >C24. The two literature‐based hypotheses to be tested were the importance of the amount of wax esters and the weighted mean carbon chain length in restricting cuticular water loss. The main results were acquired by chemical analysis of cuticular wax and gravimetric cuticular transpiration measurements. Besides additional physiological measurements, the leaf surface properties were characterised by scanning electron microscopy and spectrophotometric light reflectance quantification. Mutation of the CER6 gene resulted in striking changes in qualitative wax composition but not quantitative wax amount. Based on the strong accumulation of dimeric wax esters, the relative proportion of esters increased to >90%, and the weighted mean carbon chain length increased by >6 carbon atoms. These qualitative alterations were found to increase the cuticular transpiration of leaves by twofold. Our results do not support the hypotheses that enhanced amounts of wax esters or increased weighted mean carbon chain lengths of waxes lead to reduced cuticular transpiration.
Summary statement
Mutation of the CER6 gene in Populus × canescens significantly increased the proportion of wax esters and the weighted mean carbon chain length of the cuticular wax. However, in contrast to literature‐based expectations, these alterations increased the cuticular transpiration by twofold.
Structured doctoral education is increasingly preferred compared to the individual model. Several science policy organisations give recommendations on how to structure doctoral education. However, ...there is little research on to what extent these recommendations find their way into practice. In our study, we first compared European and German recommendations on doctoral education with, second, the institutional regulations of structured doctoral programmes (N = 98) in the life sciences at twelve different German universities. Additionally, we third asked doctoral graduates (N = 1796) of these structured doctoral programmes and graduates of individual doctoral studies about their experience in doctoral education. Fourth, we contrasted the regulations of structured doctoral programmes with the reported experiences of their graduates. We found significant deviations of the reported practices of graduates from the regulations of their organisations, regarding the student admission, supervision and curricular activities of doctoral candidates. The efficacy of structured versus traditional doctoral education should be examined based on reported practice rather than on the respective written regulations.
Oxidative stress is a key concept in basic, translational, and clinical research to understand the pathophysiology of various disorders, including cardiovascular and renal diseases. Although attempts ...to directly reduce oxidative stress with redox-active substances have until now largely failed to prove clinical benefit, indirect approaches to combat oxidative stress enzymatically have gained further attention as potential therapeutic strategies. The pantetheinase Vanin-1 is expressed on kidney proximal tubular cells, and its reaction product cysteamine is described to negatively affect redox homeostasis by inhibiting the replenishment of cellular antioxidative glutathione stores. Vanin-1-deficient mice were shown to be protected against oxidative stress damage. The aim of this study was to elucidate whether pharmacological inhibition of Vanin-1 protects mice from oxidative stress-related acute or chronic kidney injury as well. By studying renal ischemia-reperfusion injury in Col4α3
(Alport syndrome) mice and in vitro hypoxia-reoxygenation in human proximal tubular cells we found that treatment with a selective and potent Vanin-1 inhibitor resulted in ample inhibition of enzymatic activity in vitro and in vivo. However, surrogate parameters of metabolic and redox homeostasis were only partially and insufficiently affected. Consequently, apoptosis and reactive oxygen species level in tubular cells as well as overall kidney function and fibrotic processes were not improved by Vanin-1 inhibition. We thus conclude that Vanin-1 functionality in the context of cardiovascular diseases needs further investigation and the biological relevance of pharmacological Vanin-1 inhibition for the treatment of kidney diseases remains to be proven.
The role of the endothelium is not just limited to acting as an inert barrier for facilitating blood transport. Endothelial cells (ECs), through expression of a repertoire of angiocrine molecules, ...regulate metabolic demands in an organ‐specific manner. Insulin flux across the endothelium to muscle cells is a rate‐limiting process influencing insulin‐mediated lowering of blood glucose. Here, we demonstrate that Notch signaling in ECs regulates insulin transport to muscle. Notch signaling activity was higher in ECs isolated from obese mice compared to non‐obese. Sustained Notch signaling in ECs lowered insulin sensitivity and increased blood glucose levels. On the contrary, EC‐specific inhibition of Notch signaling increased insulin sensitivity and improved glucose tolerance and glucose uptake in muscle in a high‐fat diet‐induced insulin resistance model. This was associated with increased transcription of Cav1, Cav2, and Cavin1, higher number of caveolae in ECs, and insulin uptake rates, as well as increased microvessel density. These data imply that Notch signaling in the endothelium actively controls insulin sensitivity and glucose homeostasis and may therefore represent a therapeutic target for diabetes.
Synopsis
Insulin flux from blood plasma to muscle cells across the endothelium is a critical step in insulin‐mediated lowering of blood glucose levels. This study highlights the role of Notch signaling in regulating systemic glucose homeostasis.
Notch signaling activity was higher in endothelial cells (ECs) isolated from obese mice compared to non‐obese mice.
Sustained Notch signaling in ECs lowered insulin sensitivity and increased blood glucose levels in mice.
EC‐specific inhibition of canonical Notch signaling increased insulin sensitivity and improved glucose tolerance in a high‐fat diet‐induced insulin resistance model.
Glucose tolerance improvement was associated with increased transcription of genes involved in caveolae formation (Cav1 and Cavin1), higher number of caveolae in ECs and insulin uptake rates.
Insulin flux from blood plasma to muscle cells across the endothelium is a critical step in insulin‐mediated lowering of blood glucose levels. This study highlights the role of Notch signaling in regulating systemic glucose homeostasis.
Monitoring of measurable residual disease (MRD) provides prognostic information in patients with Nucleophosmin1-mutated (NPM1mut) acute myeloid leukemia (AML) and represents a powerful tool to ...evaluate treatment effects within clinical trials. We determined NPM1mut transcript levels (TLs) by quantitative reverse-transcription polymerase chain reaction and evaluated the prognostic impact of NPM1mut MRD and the effect of gemtuzumab ozogamicin (GO) on NPM1mut TLs and the cumulative incidence of relapse (CIR) in patients with NPM1mut AML enrolled in the randomized phase 3 AMLSG 09-09 trial. A total of 3733 bone marrow (BM) samples and 3793 peripheral blood (PB) samples from 469 patients were analyzed. NPM1mut TL log10 reduction ≥ 3 and achievement of MRD negativity in BM and PB were significantly associated with a lower CIR rate, after 2 treatment cycles and at end of treatment (EOT). In multivariate analyses, MRD positivity was consistently revealed to be a poor prognostic factor in BM and PB. With regard to treatment effect, the median NPM1mut TLs were significantly lower in the GO-Arm across all treatment cycles, resulting in a significantly greater proportion of patients achieving MRD negativity at EOT (56% vs 41%; P = .01). The better reduction in NPM1mut TLs after 2 treatment cycles in MRD positive patients by the addition of GO led to a significantly lower CIR rate (4-year CIR, 29.3% vs 45.7%, P = .009). In conclusion, the addition of GO to intensive chemotherapy in NPM1mut AML resulted in a significantly better reduction in NPM1mut TLs across all treatment cycles, leading to a significantly lower relapse rate.
Arthropod venoms consist primarily of peptide toxins that are injected into their prey with devastating consequences. Venom proteins are thought to be recruited from endogenous body proteins and ...mutated to yield neofunctionalized toxins with remarkable affinity for specific subtypes of ion channels and receptors. However, the evolutionary history of venom peptides remains poorly understood. Here we show that a neuropeptide hormone has been convergently recruited into the venom of spiders and centipedes and evolved into a highly stable toxin through divergent modification of the ancestral gene. High-resolution structures of representative hormone-derived toxins revealed they possess a unique structure and disulfide framework and that the key structural adaptation in weaponization of the ancestral hormone was loss of a C-terminal α helix, an adaptation that occurred independently in spiders and centipedes. Our results raise a new paradigm for toxin evolution and highlight the value of structural information in providing insight into protein evolution.
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•ITP/CHH hormones were convergently recruited into the venom of spiders and centipedes•Venom ITP/CHH peptides were weaponized via key structural adaptations to form toxins•ITP/CHH-derived toxins are defined by a helical fold that is unique for venom proteins•We report the first three-dimensional structure of any centipede protein
Undheim et al. introduce a new class of venom peptides and show that they are derived from an ancient family of hormones. These hormones were convergently recruited into spider and centipede venom and subsequently weaponized for life as a toxin via key structural adaptations.
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