Populus from high altitude has more efficient protective mechanisms under water stress than from low-altitude habitats: a study in greenhouse for cuttings

Cuttings of Populus przewalskii and P. cathayana, which originated from high and low altitudes in southwest China, were used to examine the effect of water stress on the morphological, physiological and biochemical traits of plants in a greenhouse for one growing season. The dry mass accumulation and allocation, gas exchanges, extent of peroxidation damage, osmotic adjustment and antioxidative defenses, and amounts of pigments were measured to characterize the differences in peroxidation damage and protective mechanisms of two poplar species that contrast in drought tolerance. Under water stress, poplars showed a series of biochemical adjustments and morphological changes as follows: a decrease in leaf relative water content, gas exchanges, plant growth and dry mass accumulation; an increase in relative allocation to roots; an increase in the osmolyte contents (e.g. total amino acids). Additionally, water deficit induced an increase in peroxidation damage [as indicated by an increase in electrolyte leakage, malondialdehyde (MDA), carbonyl (C = O ) and hydrogen peroxide (H₂O₂) content], enhanced activities or contents of antioxidants (e.g. ascorbate peroxidase, guaiacol peroxidase, glutathione redutase and ascorbic acid) and reduced amounts of leaf pigments (e.g. chlorophyll and carotenoid). Furthermore, there were significant differences in the extent of morphological and biochemical changes between the two poplar species. Compared with P. cathayana, P. przewalskii responded to water stress by allocating relatively more to root dry mass, possessing a higher net photosynthesis rate, and having more efficient protective mechanisms, such as more osmolyte accumulation, stronger antioxidant activities and lower chlorophyll/carotenoid ratio. Thus, P. przewalskii suffered less damage as deduced from lower levels of electrolyte leakage, MDA, C=O and H₂O₂ content. Therefore, P. przewalskii originating from high altitude could possess more efficient protective mechanisms than P. cathayana, which is from low‐altitude habitats.     

Global analysis of the rat and human platelet proteome – the molecular blueprint for illustrating multi‐functional platelets and cross‐species function evolution

Emerging evidences indicate that blood platelets function in multiple biological processes including immune response, bone metastasis and liver regeneration in addition to their known roles in hemostasis and thrombosis. Global elucidation of platelet proteome will provide the molecular base of these platelet functions. Here, we set up a high‐throughput platform for maximum exploration of the rat/human platelet proteome using integrated proteomic technologies, and then applied to identify the largest number of the proteins expressed in both rat and human platelets. After stringent statistical filtration, a total of 837 unique proteins matched with at least two unique peptides were precisely identified, making it the first comprehensive protein database so far for rat platelets. Meanwhile, quantitative analyses of the thrombin‐stimulated platelets offered great insights into the biological functions of platelet proteins and therefore confirmed our global profiling data. A comparative proteomic analysis between rat and human platelets was also conducted, which revealed not only a significant similarity, but also an across‐species evolutionary link that the orthologous proteins representing “core proteome”, and the “evolutionary proteome” is actually a relatively static proteome.     

Differences in some morphological, physiological, and biochemical responses to drought stress in two contrasting populations of Populus przewalskii

The cuttings of Populus przewalskii Maximowicz were exposed to three different watering regimes (100, 50, and 25% of the field capacity) in a greenhouse to characterize the morphological, physiological, and biochemical basis of drought tolerance in woody plants. Two contrasting populations of P. przewalskii were used in our study, which were from the wet and dry climate regions in western China, respectively. The results showed that there were significant differences in responses to three different watering regimes in both populations tested; drought not only significantly affected dry mass accumulation and partitioning but also significantly decreased chlorophyll pigment contents and accumulated free proline and total amino acids. On the other hand, drought also significantly increased the levels of abscisic acid, hydrogen peroxide, and superoxide radical as secondary messengers to induce the entire set of antioxidative systems including the increase of reduced ascorbic acid (ASA) content and the activities of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase, and glutathione reductase (GR). Moreover, there were different responses to drought stress between the two contrasting populations of P. przewalskii . Compared to the wet climate population, the dry climate population showed lower dry matter accumulation and partitioned more biomass to root systems, and accumulated more free proline and total amino acids for osmotic adjustment. The dry climate population also showed more efficient antioxidant systems with higher content of ASA and higher activities of ascorbate peroxidase and GR than the wet climate population.     

PLPPR4 haploinsufficiency causes neurodevelopmental disorders by disrupting synaptic plasticity via mTOR signalling

Phospholipid phosphatase related 4 (PLPPR4), a neuron-specific membrane protein located at the postsynaptic density of glutamatergic synapses, is a putative regulator of neuronal plasticity. However, PLPPR4 dysfunction has not been linked to genetic disorders. In this study, we report three unrelated patients with intellectual disability (ID) or autism spectrum disorder (ASD) who harbour a de novo heterozygous copy number loss of PLPPR4 in 1p21.2p21.3, a heterozygous nonsense mutation in PLPPR4 (NM_014839, c.4C > T, p.Gln2*) and a homozygous splice mutation in PLPPR4 (NM_014839: c.408 + 2 T > C), respectively. Bionano single-molecule optical mapping confirmed PLPPR4 deletion contains no additional pathogenic genes. Our results suggested that the loss of function of PLPPR4 is associated with neurodevelopmental disorders. To test the pathogenesis of PLPPR4, peripheral blood mononuclear cells obtained from the patient with heterozygous deletion of PLPPR4 were induced to specific iPSCs (CHWi001-A) and then differentiated into neurons. The neurons carrying the deletion of PLPPR4 displayed the reduced density of dendritic protrusions, shorter neurites and reduced axon length, suggesting the causal role of PLPPR4 in neurodevelopmental disorders. As the mTOR signalling pathway was essential for regulating the axon maturation and function, we found that mTOR signalling was inhibited with a higher level of p-AKT, p-mTOR and p-ERK1/2, decreased p-PI3K in PLPPR4-iPSCs neurons. Additionally, we found silencing PLPPR4 disturbed the mTOR signalling pathway. Our results suggested PLPPR4 modulates neurodevelopment by affecting the plasticity of neurons via the mTOR signalling pathway.     

Responses of root exudation and nutrient cycling to grazing intensities and recovery practices in an alpine meadow: An implication for pasture management

Plant and Soil - The rhizosphere priming effect is caused by root carbon (C) exudation into the rhizosphere; the role of this effect in nutrient cycling and ecosystem recovery of natural grasslands...     

Germplasm,chemical constituents,biological activities,utilization, and control of Chinese tallow (<Emphasis Type="Italic">Triadica sebifera</Emphasis> (L.) Small)

Chinese tallow (Triadica sebifera, also known as Sapium sebiferum) is an important oil seed crop in its native China but has become a noxious invasive species in USA. This review covers 601 publications since 1946. To date, grape (var. conferticarpa), chicken claw (var. laxiarpa), long claw, and mixed types are recognized within the species with 77 compounds isolated from various tissues. Some of the known 13 tetracyclic diterpenoids or phorbols showed pro-inflammatory and skin irritant activities or antibacterial and antiviral activities. In contrast, leaf extracts of T. sebifera showed analgesic and anti-inflammatory activities in animal models. Tallow leaves have been used to treated bacterial infections in birds and fish in China and also showed molluscicidal activities. Seed fats and oils have a long history of uses in China. The seed aril has been used to produce Chinese tallow cocoa butter equivalent since the late 1980s, but product quality and cost need improvement. The kernel oil showed promising potential for biodiesel production. In USA, the plantings were well developed before the mid-1900s since it introduced in 1772. The tree spread quickly in the southeastern USA due to its high fertility, fast growth and broad adaptability, lack of natural enemies, increasing habitat fragmentation, disturbance events like hurricanes, and selection and development of superior high-seed yield cultivars/clones. It is now considered as one of the worst invasive species in the area. Its conventional herbicide, biological, and mechanical control methods are costly, and either largely ineffective or not environmental friendly.     

Optimizing foliar allocation of limiting nutrients and fast‐slow economic strategies drive forest succession along a glacier retreating chronosequence in the eastern Tibetan Plateau

Plant and Soil - Nitrogen (N) and phosphorus (P) availabilities limit plant productivity, especially in primary succession; however, our understanding of species-specific strategies regarding their...     

Endotoxin tolerance impairs IL-1 receptor-associated kinase (IRAK) 4 and TGF-beta-activated kinase 1 activation, K63-linked polyubiquitination and assembly of IRAK1, TNF receptor-associated factor 6, and IkappaB kinase gamma and increases A20 expression

Endotoxin tolerance reprograms Toll-like receptor 4 responses by impairing LPS-elicited production of pro-inflammatory cytokines without inhibiting expression of anti-inflammatory or anti-microbial mediators. In septic patients, Toll-like receptor tolerance is thought to underlie decreased pro-inflammatory cytokine expression in response to LPS and increased incidence of microbial infections. The impact of endotoxin tolerance on recruitment, post-translational modifications and signalosome assembly of IL-1 receptor-associated kinase (IRAK) 4, IRAK1, TNF receptor-associated factor (TRAF) 6, TGF-β-activated kinase (TAK) 1, and IκB kinase (IKK) γ is largely unknown. We report that endotoxin tolerization of THP1 cells and human monocytes impairs LPS-mediated receptor recruitment and activation of IRAK4, ablates K63-linked polyubiquitination of IRAK1 and TRAF6, compromises assembly of IRAK1-TRAF6 and IRAK1-IKKγ platforms, and inhibits TAK1 activation. Deficiencies in these signaling events in LPS-tolerant cells coincided with increased expression of A20, an essential deubiquitination enzyme, and sustained A20-IRAK1 associations. Overexpression of A20 inhibited LPS-induced activation of NF-κB and ablated NF-κB reporter activation driven by ectopic expression of MyD88, IRAK1, IRAK2, TRAF6, and TAK1/TAB1, while not affecting the responses induced by IKKβ and p65. A20 shRNA knockdown abolished LPS tolerization of THP1 cells, mechanistically linking A20 and endotoxin tolerance. Thus, deficient LPS-induced activation of IRAK4 and TAK1, K63-linked polyubiquitination of IRAK1 and TRAF6, and disrupted IRAK1-TRAF6 and IRAK1-IKKγ assembly associated with increased A20 expression and A20-IRAK1 interactions are new determinants of endotoxin tolerance.     

Discovery of biomarker candidates for coronary artery disease from an APOE-knock out mouse model using iTRAQ-based multiplex quantitative proteomics

Due to the lack of precise markers indicative of its occurrence and progression, coronary artery disease (CAD), the most common type of heart diseases, is currently associated with high mortality in the United States. To systemically identify novel protein biomarkers associated with CAD progression for early diagnosis and possible therapeutic intervention, we employed an iTRAQ‐based quantitative proteomic approach to analyze the proteome changes in the plasma collected from a pair of wild‐type versus apolipoprotein E knockout (APOE^?/?) mice which were fed with a high fat diet. In a multiplex manner, iTRAQ serves as the quantitative ‘in‐spectra’ marker for ‘cross‐sample’ comparisons to determine the differentially expressed/secreted proteins caused by APOE knock‐out. To obtain the most comprehensive proteomic data sets from this CAD‐associated mouse model, we applied both MALDI and ESI‐based mass spectrometric (MS) platforms coupled with two different schemes of multidimensional liquid chromatography (2‐D LC) separation. We then comparatively analyzed a series of the plasma samples collected at 6 and 12 wk of age after the mice were fed with fat diets, where the 6‐ or 12‐wk time point represents the early or intermediate phase of the fat‐induced CAD, respectively. We then categorized those proteins showing abundance changes in accordance with APOE depletion. Several proteins such as the γ and β chains of fibrinogen, apolipoprotein B, apolipoprotein C‐I, and thrombospondin‐4 were among the previously known CAD markers identified by other methods. Our results suggested that these unbiased proteomic methods are both feasible and a practical means of discovering potential biomarkers associated with CAD progression.