Ecophysiological responses of two closely related Magnoliaceae genera to seasonal changes in subtropical China

Plants use a variety of hydraulic strategies to adapt to seasonal drought that differ by species and environmental conditions. The early-diverging Magnoliaceae family includes two closely related genera with contrasting leaf habits, Yulania (deciduous) andMichelia (evergreen), which naturally inhabit temperate and tropical regions, respectively. Here, we evaluate the hydraulic strategy of species from both genera that have beenex situ conserved in a subtropical region to determine how they respond to the novel cool-dry season climatic pattern. We measured ecophysiological traits in fiveMichelia and fiveYulania species conserved in the South China Botanical Garden in both wet and dry season conditions and monitored the whole-year sap flow for four of these species. We found that Magnoliaceae species that have beenex situ conserved in a subtropical climate did not suffer from excessive water stress due to the mild drought conditions of the dry season and the ecophysiological adjustments the species made to avoid this stress, which differed by leaf habit. Specifically, deciduous species completely shed their leaves during the dry season, while evergreen species decreased their turgor loss points, dry mass based photosynthetic rates, stomatal conductance and specific leaf areas (SLAs) compared to wet season measurements. In comparing the two distinct leaf habits during the wet season, the leathery-leaved evergreen species had higher leaf hydraulic conductance and leaf to sapwood area ratios than the papery-leaved deciduous species, while the deciduous species had greater hydraulic conductivity calculated on both a stem and leaf area basis, dry mass based photosynthetic rates, leaf nutrients, SLAs and stomatal sizes than the evergreen species. Interestingly, species from both genera maintained similar sap flow in the wet season. Both photosynthetically active radiation and vapour pressure deficit affected the diurnal patterns of sap flow in the wet season, while only vapour pressure deficit played a dominant role in the dry season. This study reveals contrasting hydraulic strategies inYulania andMichelia species under subtropical seasonal conditions, and suggests that these ecophysiological adjustments might be affected more by leaf habit than seasonality, thus reflecting the divergent evolution of the two closely related genera. Furthermore, we show that Magnoliaceae species that areex situ conserved in a subtropical climate are hydraulically sound, a finding that will inform future conservation efforts of this ancient family under the threat of climatic change

THE EEMD-RA-KU METHOD ON DIAGNOSIS OF BEARING FAULT

Aiming at the impact feature in fault signals of the rolling bearings,The improved algorithm diagnosis method EEMD-RA-KU was proposed to capture the impact feature. Firstly,Fault signals were decomposed into a series of intrinsic mode functions（ IMFs） with ensemble empirical mode decomposition（ EEMD）. Secondly,The IMFs were selected to reconstruct signals based on relative analysis（ RA） and kurtosis（ KU）. Thirdly,The reconstructed signals were filtered by the filter that the parameters were determined with the spectral kurtosis. Finally,The fault can be diagnosed by comparing the frequency of the envelope spectrum with the fault characteristic frequency of the bearing. The result shows that the fault feature information of the signal can be extracted accurately when there was a lot of background noise

The Distribution Frequency of Interferon-Gamma Receptor 1 Gene Polymorphisms in Interferon-γ Release Assay-Positive Patients

Tuberculosis is caused by mycobacterium, a potentially fatal infectious bacterium. In recent years, TB cases increased in the whole world. WHO statistics data shows that the world’s annual tuberculosis incidence was 8~10 million with about 3 million deaths. Several studies have shown that susceptibility to tuberculosis may be associated with IFNGR1 gene polymorphisms. Here, we report the distribution frequency of IFNGR1 gene polymorphisms in 103 cases of IGA-negative patients and 100 cases of IGA-positive patients from China by sequencing the IFNGR1 proximal ~750 bp promoter region. We found a total of 5 types of site mutations: -611 (G/A), -56 (T/C), -255 (C/T), -359 (T/C), and -72 (C/T). The two main types of gene polymorphisms among the IGA-negative and IGA-positive groups were -611 (G/A), with mutation rates of 88.3% and 78.4%, respectively, and -56 (T/C), with mutation rates of 84.5% and 83.8%, respectively, which had no statistical significance, and there was no correlation with the incidence of tuberculosis

The 3/4- and 3/6-Subfamily Variants of α-Conotoxins GI and MI Exhibit Potent Inhibitory Activity against Muscular Nicotinic Acetylcholine Receptors

α-Conotoxins GI and MI belong to the 3/5 subfamily of α-conotoxins and potently inhibit muscular nicotinic acetylcholine receptors (nAChRs). To date, no 3/4- or 3/6-subfamily α-conotoxins have been reported to inhibit muscular nAChRs. In the present study, a series of new 3/4-, 3/6-, and 3/7-subfamily GI and MI variants were synthesized and functionally characterized by modifications of loop2. The results show that the 3/4-subfamily GI variant GI[∆8G]-II and the 3/6-subfamily variants GI[+13A], GI[+13R], and GI[+13K] displayed potent inhibition of muscular nAChRs expressed in Xenopus oocytes, with an IC50 of 45.4–73.4 nM, similar to or slightly lower than that of wild-type GI (42.0 nM). The toxicity of these GI variants in mice appeared to be about a half to a quarter of that of wild-type GI. At the same time, the 3/7-subfamily GI variants showed significantly lower in vitro potency and toxicity. On the other hand, similar to the 3/6-subfamily GI variants, the 3/6-subfamily MI variants MI[+14R] and MI[+14K] were also active after the addition of a basic amino acid, Arg or Lys, in loop2, but the activity was not maintained for the 3/4-subfamily MI variant MI[∆9G]. Interestingly, the disulfide bond connectivity “C1–C4, C2–C3” in the 3/4-subfamily variant GI[∆8G]-II was significantly more potent than the “C1–C3, C2–C4” connectivity found in wild-type GI and MI, suggesting that disulfide bond connectivity is easily affected in the rigid 3/4-subfamily α-conotoxins and that the disulfide bonds significantly impact the variants’ function. This work is the first to demonstrate that 3/4- and 3/6-subfamily α-conotoxins potently inhibit muscular nAChRs, expanding our knowledge of α-conotoxins and providing new motifs for their further modifications

Molecular Modeling of Ammonia Gas Adsorption onto the Kaolinite Surface with DFT Study

With high porosity and being one of the most abundant clay minerals, dried kaolinite may be an excellent adsorbent to remove ammonia gas (NH3). Here, the plane wave pseudopotential method based on density functional theory (DFT) was used to explore the mechanism of ammonia gas adsorption on the dried kaolinite, the Mulliken electric charge, and the partial density of states of atoms of the NH3/kaolinite (001) system. NH3 adsorption on kaolinite can happen in three different type adsorption positions: “top”, “bridge” and “hollow”. The “hollow” position is enclosed by two "upright" hydroxyl groups perpendicular to the (001) surface of kaolinite and a "lying" hydroxyl group parallel to the surface. At this position, the adsorption is the most stable and has the highest adsorption energy. The nitrogen atom of the NH3 molecule bonds with the hydrogen atom in the "upright" hydroxyl group on the (001) surface and its hydrogen atom forms HN…O hydrogen bond with oxygen atom in the "lying" hydroxyl group, which leads to the NH3 stably adsorbed on kaolinite (001) surface. A small part of electrons transfer between NH3 molecules and kaolinite creates weakly electrostatic adsorption between them

Exogenous Melatonin Positively Regulates Rice Root Growth through Promoting the Antioxidant System and Mediating the Auxin Signaling under Root-Zone Hypoxia Stress

Root growth and development is an important indicator of root-zone hypoxia tolerance in rice. Melatonin has been suggested to function as a crucial regulator in modulating root growth and improving plant abiotic stress resistance. To explore the role and potential mechanism of melatonin in regulating the root growth under root-zone hypoxia stress, rice seedlings were treated with hypoxia (oxygen level at 0.9–2.1 mg·L−1), combined with or without a 20 μmol·L−1 melatonin pretreatment under a hydroponic condition. The results showed that the exogenous application of melatonin significantly alleviated the inhibition of the rice root growth that was induced by the hypoxia stress. The morphological–phenotypic analyses showed that after the melatonin pretreatment, the primary root length, lateral root length, and lateral root density increased by 11.6%, 8.2%, and 36.8%, respectively, under hypoxia stress. The physiological–biochemical analyses showed that the exogenous melatonin significantly increased the root activity and O2 influx in the root meristem zone under hypoxia stress to 1.5 times that observed in the hypoxia stress group. The melatonin pretreatment significantly improved the activity of superoxide dismutase (SOD) and decreased the accumulation of superoxide anions (O2•−) in the seedling roots, whereas it increased the content of hydrogen peroxide (H2O2) under hypoxia stress. The exogenous melatonin pretreatment significantly increased the content of indole-3-acetic acid (IAA) by 51.5% in the rice roots compared to the plants without melatonin pretreatment under hypoxia stress. Quantitative real-time PCR (qRT-PCR) analyses revealed that the melatonin pretreatment induced the expression of OsPIN1a~1d, OsPIN8, OsPIN9, OsAUX1, OsARF19, and OsGH3-2 in the rice seedling roots under aerated conditions, whereas it only obviously upregulated the expression of OsPIN1b, OsPIN2, and OsGH3-2 under hypoxia stress. These results indicate that melatonin positively regulates root growth and development under hypoxia stress, through improving the antioxidant system and directly or indirectly activating the auxin signaling pathway. This study demonstrates the important role of melatonin to modulate root growth under hypoxia stress, providing a new strategy for improving hypoxia tolerance

Exogenous Melatonin Positively Regulates Rice Root Growth through Promoting the Antioxidant System and Mediating the Auxin Signaling under Root-Zone Hypoxia Stress

Root growth and development is an important indicator of root-zone hypoxia tolerance in rice. Melatonin has been suggested to function as a crucial regulator in modulating root growth and improving plant abiotic stress resistance. To explore the role and potential mechanism of melatonin in regulating the root growth under root-zone hypoxia stress, rice seedlings were treated with hypoxia (oxygen level at 0.9–2.1 mg·L−1), combined with or without a 20 μmol·L−1 melatonin pretreatment under a hydroponic condition. The results showed that the exogenous application of melatonin significantly alleviated the inhibition of the rice root growth that was induced by the hypoxia stress. The morphological–phenotypic analyses showed that after the melatonin pretreatment, the primary root length, lateral root length, and lateral root density increased by 11.6%, 8.2%, and 36.8%, respectively, under hypoxia stress. The physiological–biochemical analyses showed that the exogenous melatonin significantly increased the root activity and O2 influx in the root meristem zone under hypoxia stress to 1.5 times that observed in the hypoxia stress group. The melatonin pretreatment significantly improved the activity of superoxide dismutase (SOD) and decreased the accumulation of superoxide anions (O2•−) in the seedling roots, whereas it increased the content of hydrogen peroxide (H2O2) under hypoxia stress. The exogenous melatonin pretreatment significantly increased the content of indole-3-acetic acid (IAA) by 51.5% in the rice roots compared to the plants without melatonin pretreatment under hypoxia stress. Quantitative real-time PCR (qRT-PCR) analyses revealed that the melatonin pretreatment induced the expression of OsPIN1a~1d, OsPIN8, OsPIN9, OsAUX1, OsARF19, and OsGH3-2 in the rice seedling roots under aerated conditions, whereas it only obviously upregulated the expression of OsPIN1b, OsPIN2, and OsGH3-2 under hypoxia stress. These results indicate that melatonin positively regulates root growth and development under hypoxia stress, through improving the antioxidant system and directly or indirectly activating the auxin signaling pathway. This study demonstrates the important role of melatonin to modulate root growth under hypoxia stress, providing a new strategy for improving hypoxia tolerance