Self S-RNase inhibits ABF-LRX signaling to arrest pollen tube growth to achieve self-incompatibility in pear.

Gametophytic self-incompatibility (GSI) has been widely studied in flowering plants, but studies of the mechanisms underlying pollen tube growth arrest by self S-RNase in GSI species are limited. In the present study, two leucine-rich repeat extensin genes in pear (Pyrus bretschneideri), PbLRXA2.1 and PbLRXA2.2, were identified based on transcriptome and quantitative real-time PCR analyses. The expression levels of these two LRX genes were significantly higher in the pollen grains and pollen tubes of the self-compatible cultivar 'Jinzhui' (harboring a spontaneous bud mutation) than in those of the self-incompatible cultivar 'Yali'. Both PbLRXA2.1 and PbLRXA2.2 stimulated pollen tube growth and attenuated the inhibitory effects of self S-RNase on pollen tube growth by stabilizing the actin cytoskeleton and enhancing cell wall integrity. These results indicate that abnormal expression of PbLRXA2.1 and PbLRXA2.2 is involved in the loss of self-incompatibility in 'Jinzhui'. The PbLRXA2.1 and PbLRXA2.2 promoters were directly bound by the ABRE-binding factor PbABF.D.2. Knockdown of PbABF.D.2 decreased PbLRXA2.1 and PbLRXA2.2 expression and inhibited pollen tube growth. Notably, the expression of PbLRXA2.1, PbLRXA2.2, and PbABF.D.2 was repressed by self S-RNase, suggesting that self S-RNase can arrest pollen tube growth by restricting the PbABF.D.2-PbLRXA2.1/PbLRXA2.2 signal cascade. These results provide novel insight into pollen tube growth arrest by self S-RNase.

Keguizhuia sedimenti gen. nov., sp. nov., isolated from river sediment represents a novel genus of the family Oxalobacteraceae.

A Gram-stain-negative bacterium, designated as R-40T, was isolated from sediment of the Mulong river in Mianyang city, Sichuan province, PR China. The cells of strain R-40T were aerobic non-motile and formed translucent white colonies on R2A agar. Growth occurred at 15-37 °C (optimum 30 °C), pH 5.0-9.0 (optimum 7.0) and salinities of 0-3.0 % (w/v, optimum 0 %). R-40T showed 95.2-96.6 % 16S rRNA gene sequence similarities with the type strains of species of the genera Oxalicibacterium, Herminiimonas, Lacisediminimonas, Paucimonas, Herbaspirillum and Noviherbaspirillum in the family Oxalobacteraceae. The results of phylogenetic analysis based on genome sequences indicated that the strain was clustered with type strains of species of the genera Oxalicibacterium and Herminiimonas in the family Oxalobacteraceae but formed a distinct lineage. The average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH) and average amino acid identity (AAI) values between R-40T and type strains of species of the genera Oxalicibacterium, Herminiimonas, Lacisediminimonas, Paucimonas, Herbaspirillum and Noviherbaspirillum ranged from 69.3 to 74.1 %, from 18.2 to 21.4 % and from 60.1 to 67.4 %, respectively. The major cellular fatty acids were C16 : 0, C17 : 0 cyclo and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The major quinone was ubiquinone-8 (Q-8). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phospholipid and small amounts of glycophospholipids. The genome size of R-40T was 5.1 Mbp with 54.0 % DNA G+C content. On the basis of the evidence presented in this study, strain R-40T represents a novel species of a novel genus in the family Oxalobacteraceae, for which the name Keguizhuia sedimenti gen. nov., sp. nov. (type strain R-40T=MCCC 1K08818T=KCTC 8137T) is proposed.

Yanghanlia caeni gen. nov., sp. nov., a novel taxon within the family Alcaligenaceae isolated from sludge of a pesticide-manufacturing factory.

A Gram-stain-negative bacterium, designated LG-2T, was isolated from sludge collected at a pesticide-manufacturing factory in Jiangsu Province, PR China. Cells of strain LG-2T were strictly aerobic, non-motile and spherical. Growth was observed at 15-42 °C (optimum, 30 °C), pH 6.0-9.0 (optimum, pH 7.0) and 0-3.0 % (w/v) NaCl (optimum, 1.0 %). LG-2T showed 95.5-96.9 % 16S rRNA sequence similarity to type strains in the genera Pusillimonas, Bordetella, Parapusillimonas, Candidimonas and Paracandidimonas of the family Alcaligenaceae. The phylogenomic tree indicated that strain LG-2T was clustered in the family Alcaligenaceae and formed a clade with Paracandidimonas soli IMT-305T, while the phylogenetic trees based on 16S rRNA gene sequences indicated that strain LG-2T formed a distinct clade within the family Alcaligenaceae. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values between LG-2T and its closely related type strains in the genera Pusillimonas, Bordetella, Parapusillimonas, Candidimonas and Paracandidimonas were 70.8-75.3, 18.9-23.7 and 59.6 %-69.3 %, respectively. The major cellular fatty acids were C16 : 0, C17 : 0 cyclo, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) and summed feature 2 (C12 : 0 aldehyde and/or unknown 10.928). The predominant menaquinone was Q-8. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, two aminophospholipids, three aminolipids and nine unknown polar lipids. The genome size of strain LG-2T was 3.2 Mb and the DNA G+C content was 63.4 mol%. On the basis of the phenotypic, phylogenetic and genomic results from this study, strain LG-2T represents a novel species of a new genus in the family Alcaligenaceae, for which the name Yanghanlia caeni gen. nov., sp. nov. is proposed, with strain LG-2T (=KCTC 8084T= CCTCC AB 2023123T) as the type strain.

Paenibacillus lacisoli sp. nov., a mesotrione-degrading strain isolated from lakeside soil.

A Gram-stain-positive, facultatively anaerobic, rod-shaped bacterium, designated JX-17T, was isolated from a soil sample collected in Jiangxi Province, PR China. Growth was observed at 15-48 °C (optimum 37 °C), at pH 5.0-9.0 (optimum pH 7.0) and with 0-6.0% (w/v) NaCl (optimum 1.0%). Strain JX-17T could degrade approximately 50% of 50 mg/L mesotrione within 2 days of incubation, but could not use mesotrione as sole carbon source for growth. Strain JX-17T showed less than 95.3% 16S rRNA gene sequence similarity with type strains of the genus Paenibacillus. In the phylogenetic tree based on 16S rRNA gene and genome sequences, strain JX-17T formed a distinct lineage within the genus Paenibacillus. The ANI values between JX-17T and the most closely related type strains P. lentus CMG1240T and P. farraposensis UY79T were 70.1% and 71.4%, respectively, and the dDDH values between them were 19.0% and 23.3%, respectively. The major cellular fatty acids were anteiso-C15:0, iso-C16:0, anteiso-C17:0 and C16:0, the predominant respiratory quinone was MK-7, the major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified glycolipid, an aminophospholipid and a phosphatidylinositol. The diagnostic diamino acid of the peptidoglycan was meso-diaminopimelic acid, and the DNA G + C content was 50.1 mol%. Based on the phylogenetic, phenotypic and chemotaxonomic characteristics, strain JX-17T represents a novel species within the genus Paenibacillus, for which the name Paenibacillus lacisoli sp. nov is proposed, with strain JX-17T (= GDMCC 1.3962T = KCTC 43568T) as the type strain.

Nocardioides imazamoxiresistens sp. nov. Isolated from the Activated Sludge.

A Gram-staining-positive actinomycete named YZH12T was isolated from the sediment of the Yangtze River in Nanjing, Jiangsu province, China. Cells were aerobic, non-spore forming, non-motile, short rod (0.4-0.6 × 0.5-1.0 µm) or coccus (0.4-0.6 µm in diameter). Colonies were circular, smooth, and beige to yellowish. Growth occurred at 15-42 °C (optimal 28 °C), pH 5.0-9.0 (optimal 7.0), and 0-10% (w/v) NaCl (optimal 2%). The strain could tolerate 1500 mg/L of imazamox. Strain YZH12T showed 98.7% 16S rRNA gene sequence similarity Nocardioides zeae JM-1068T and less than 97% similarities with other type strains in the genus Nocardioides. Phylogenetic analysis based on genome and 16S rRNA gene sequences indicated that strain YZH12T was phylogenetically affiliated to the genus Nocardioides and formed a subclade with N. zeae JM-1068T and N. alkalitolerans DSM 16699T. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between YZH12T and closely related type strain N. zeae JM-1068T were 79.9% and 35.2%, respectively. The major fatty acids (> 5%) were C18: 1ω9c, iso-C16: 0, C16: 0, C17: 1ω8cand C18: 0; the major respiratory quinone was MK-8(H4); and the polar lipids profiles were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), glycolipid (GL), two aminophospholipids (APL1, APL2), and an unknown polar lipid (L). The genomic DNA G + C content is 73.5%. Based on the phenotypic, chemotaxonomic, phylogenetic analyses, and genomic data, strain YZH12T represents a novel species of the genus Nocardioides, for which the name Nocardioides imazamoxiresistens YZH12T is proposed, with strain YZH12T (= KCTC 49964T = MCCC 1K0892T) as the type strain.

Flavobacterium sedimenticola sp. nov., isolated from sediment.

A novel yellow-pigmented bacterial strain, designated YZ-48T, was isolated from the sediment of the Yangtze River, PR China. Cells were Gram-stain-negative, non-motile, rod-shaped, strictly aerobic, catalase-positive and oxidase-positive. The strain grew optimally on R2A medium at 37 °C, pH 7.0 and with 1.0 % (w/v) NaCl. Strain YZ-48T showed the closest 16S rRNA gene sequence similarity to Flavobacterium solisilvae SE-s27T (96.4 %) and F. dankookense DSM 25687T (96.2 %). The phylogenetic trees based on 16S rRNA gene sequences showed that strain YZ-48T belonged to the genus Flavobacterium but formed a distinct phylogenetic lineage. The obtained average nucleotide identity and digital DNA-DNA hybridization values between YZ-48T and the two closest strains were 75.0 and 74.5 % and 19.6 and 19.0 %, respectively. The sole respiratory quinone was MK-6. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids and three unidentified polar lipids. The major cellular fatty acids were iso-C16 : 0, iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, iso-C15 : 0 3-OH and iso-C16 : 0 3-OH. The DNA G+C content was 40.2 mol%. Based on the phenotypic, chemotaxonomic, phylogenetic and genomic data, strain YZ-48T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium sedimenticola sp. nov. is proposed, with strain YZ-48T (=KCTC 82329T=CCTC AB 2023061T=MCCC 1K08804T) as the type strain.

Empedobacter sedimenti sp. nov., isolated from sediment of East Taihu Lake.

A Gram-reaction-negative, strictly aerobic, pale yellow, non-gliding, rod-shaped bacterium, designated DT-LB-19T, was isolated from the sediment of East Taihu Lake in Jiangsu Province, PR China. Strain DT-LB-19T showed the highest 16S rRNA gene sequence similarities to members of the genera Algoriella, Chishuiella and Empedobacter (94.84-95.77 %) in the family Weeksellaceae. In phylogenetic trees based on genomes, strain DT-LB-19T clustered within the genus Empedobacter but formed a separate subclade with a high bootstrap value. The average nucleotide identity and digital DNA-DNA hybridization values between DT-LB-19T and the closely related type strains were in the range of 82.5-86.9 % and 25.8-32.3 %, respectively. The major cellular fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 1 ω5c, C16 : 0, summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and iso-C15 : 03-OH. The predominant menaquinone was menaquinone-6. The polar lipid profile consisted of phosphatidylethanolamine, one glycolipid, two aminophospholipids and five unidentified lipids. The DNA G+C content was 31.8 mol%. Based on the phenotypic, chemotaxonomic, phylogenetic and genomic results, we propose that strain DT-LB-19T represents a novel species of the genus Empedobacter, for which the name Empedobacter sedimenti sp. nov. is proposed, with strain DT-LB-19T (=KCTC 82330T=CCTCC AB 2023026T= JSACC 11448T) as the type strain.

Exploring the role of nuclear energy in the energy transition: A comparative perspective of the effects of coal, oil, natural gas, renewable energy, and nuclear power on economic growth and carbon emissions.

Nuclear power has received renewed attention during the energy transition in recent years. This study is aimed to explore whether nuclear energy can promote economic growth without increasing carbon emissions. In order to have a more comprehensive understanding of the relationship between nuclear energy, economic growth, and carbon emissions, this study also discusses the impact of coal, oil, natural gas, and renewable energy on economic growth and carbon emissions. The second-generation panel unit root test, panel cointegration test, panel fully modified ordinary least squares, and Heterogeneous Dumitrescu and Hurlin causality test were used to estimate the long-term elasticity and causality among variables. Results based on panel data from 24 countries with nuclear energy from 2001 to 2020 show that both nuclear energy and renewable energy can curb carbon emissions. Especially in Canada, Finland, Russia, Slovenia, South Korea, and The United Kingdom, nuclear energy reduces carbon emissions more significantly than renewable energy. Meanwhile, there is a positive relationship between increased nuclear energy, increased renewable energy, and economic growth, which means that nuclear energy and renewable energy could increase economic growth as well. There is a positive relationship between increased oil, increased natural gas, and economic growth, while there is a negative relationship between the increase in coal and economic growth. Meanwhile, there is a positive relationship between increased oil, increased coal, and increased carbon emissions, while the positive relationship between increased natural gas and increased carbon emissions is not significant. Thus, in the 22 countries with nuclear power, increased coal consumption does not drive economic growth but increases carbon emissions. Increased oil consumption increases economic growth, but it increases carbon emissions. Increased natural gas consumption boosts economic growth but adds little to carbon emissions. In the authors' view, nuclear power and renewable energy are all options for these nuclear-power countries to pursue economic growth without increasing carbon emissions. Moreover, nuclear power has a better effect on curbing carbon emissions in some countries than renewable energy. Therefore, under the premise of safety, nuclear power should be seriously considered and re-developed.

Echo-ID: Smartphone Placement Region Identification for Context-Aware Computing.

Region-function combinations are essential for smartphones to be intelligent and context-aware. The prerequisite for providing intelligent services is that the device can recognize the contextual region in which it resides. The existing region recognition schemes are mainly based on indoor positioning, which require pre-installed infrastructures or tedious calibration efforts or memory burden of precise locations. In addition, location classification recognition methods are limited by either their recognition granularity being too large (room-level) or too small (centimeter-level, requiring training data collection at multiple positions within the region), which constrains the applications of providing contextual awareness services based on region function combinations. In this paper, we propose a novel mobile system, called Echo-ID, that enables a phone to identify the region in which it resides without requiring any additional sensors or pre-installed infrastructure. Echo-ID applies Frequency Modulated Continuous Wave (FMCW) acoustic signals as its sensing medium which is transmitted and received by the speaker and microphones already available in common smartphones. The spatial relationships among the surrounding objects and the smartphone are extracted with a signal processing procedure. We further design a deep learning model to achieve accurate region identification, which calculate finer features inside the spatial relations, robust to phone placement uncertainty and environmental variation. Echo-ID requires users only to put their phone at two orthogonal angles for 8.5 s each inside a target region before use. We implement Echo-ID on the Android platform and evaluate it with Xiaomi 12 Pro and Honor-10 smartphones. Our experiments demonstrate that Echo-ID achieves an average accuracy of 94.6% for identifying five typical regions, with an improvement of 35.5% compared to EchoTag. The results confirm Echo-ID's robustness and effectiveness for region identification.

The negative impact of the COVID-19 on renewable energy growth in developing countries: Underestimated.

According to the United Nations Environment Programme, the COVID-19 pandemic has created challenges for the economy and the energy sector, as well as uncertainty for the renewable energy industry. However, the impact on renewable energy during the pandemic has not been consistently determined. Instead of relying on data from year-to-year comparisons, this study redesigned the analytical framework for assessing the impact of a pandemic on renewable energy. First, this research designed an "initial prediction-parameter training-error correction-assignment combination" forecasting approach to simulate renewable energy consumption in a "no pandemic" scenario. Second, this study calculates the difference between the "pandemic" and "no pandemic" scenarios for renewable energy consumption. This difference represents the change in renewable energy due to the COVID-19 pandemic. Various techniques such as nonlinear grey, artificial neural network and IOWGA operator were incorporated. The MAPEs were controlled to within 5% in 80% of the country samples. The conclusions indicated that renewable energy in China and India declined by 8.57 mtoe and 3.19 mtoe during COVID-19 period. In contrast, the rise in renewable energy in the US is overestimated by 8.01 mtoe. Overall, previous statistics based on year-to-year comparisons have led to optimistic estimates of renewable energy development during the pandemic. This study sheds light on the need for proactive policy measures in the future to counter the global low tide of renewable energy amid COVID-19.

Discovery of aromatic amides with triazole-core as potent reversal agents against P-glycoprotein-mediated multidrug resistance.

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) is a major impediment for clinical cancer therapy. 19 novel aromatic amides with triazole-core as MDR reversal agents were designed and synthesized via click chemistry to reverse MDR. Among them, compound 42 was identified as the most promising candidate with high potency (EC50 = 78.1 ±â€¯5.4 nM), low cytotoxity (SI > 1282) and persistent duration in reversing doxorubicin (DOX) resistance in K562/A02 cells. 42 also enhanced the potency of other P-gp associated cytotoxic agents with different structures. In further study, remarkably increased intracellular accumulation of Rh123 and DOX in K562/A02 cells was achieved by compound 42, while CYP3A4 activity had no change by compound 42. These results indicate that compound 42 as a relatively safe modulator of P-gp-mediated MDR has good potential for further development.

Genomic characterization, phylogenetic comparison and differential expression of the cyclic nucleotide-gated channels gene family in pear (Pyrus bretchneideri Rehd.).

The cyclic nucleotide-gated channel (CNGC) family is involved in the uptake of various cations, such as Ca(2+), to regulate plant growth and respond to biotic and abiotic stresses. However, there is far less information about this family in woody plants such as pear. Here, we provided a genome-wide identification and analysis of the CNGC gene family in pear. Phylogenetic analysis showed that the 21 pear CNGC genes could be divided into five groups (I, II, III, IVA and IVB). The majority of gene duplications in pear appeared to have been caused by segmental duplication and occurred 32.94-39.14 million years ago. Evolutionary analysis showed that positive selection had driven the evolution of pear CNGCs. Motif analyses showed that Group I CNGCs generally contained 26 motifs, which was the greatest number of motifs in all CNGC groups. Among these, eight motifs were shared by each group, suggesting that these domains play a conservative role in CNGC activity. Tissue-specific expression analysis indicated that functional diversification of the duplicated CNGC genes was a major feature of long-term evolution. Our results also suggested that the P-S6 and PBC & hinge domains had co-evolved during the evolution. These results provide valuable information to increase our understanding of the function, evolution and expression analyses of the CNGC gene family in higher plants.

Long-chain base phosphates modulate pollen tube growth via channel-mediated influx of calcium.

Long-chain base phosphates (LCBPs) have been correlated with amounts of crucial biological processes ranging from cell proliferation to apoptosis in animals. However, their functions in plants remain largely unknown. Here, we report that LCBPs, sphingosine-1-phosphate (S1P) and phytosphingosine-1-phosphate (Phyto-S1P), modulate pollen tube growth in a concentration-dependent bi-phasic manner. The pollen tube growth in the stylar transmitting tissue was promoted by SPHK1 overexpression (SPHK1-OE) but dampened by SPHK1 knockdown (SPHK1-KD) compared with wild-type of Arabidopsis; however, there was no detectable effect on in vitro pollen tube growth caused by misexpression of SPHK1. Interestingly, exogenous S1P or Phyto-S1P applications could increase the pollen tube growth rate in SPHK1-OE, SPHK1-KD and wild-type of Arabidopsis. Calcium ion (Ca(2+) )-imaging analysis showed that S1P triggered a remarkable increase in cytosolic Ca(2+) concentration in pollen. Extracellular S1P induced hyperpolarization-activated Ca(2+) currents in the pollen plasma membrane, and the Ca(2+) current activation was mediated by heterotrimeric G proteins. Moreover, the S1P-induced increase of cytosolic free Ca(2+) inhibited the influx of potassium ions in pollen tubes. Our findings suggest that LCBPs functions in a signaling cascade that facilitates Ca(2+) influx and modulates pollen tube growth.

Mitochondrial dysfunction mediated by cytoplasmic acidification results in pollen tube growth cessation in Pyrus pyrifolia.

The length of pollen tubes grown in synthetic media is normally shorter than those grown in vivo. However, the mechanism(s) underlying the cessation of pollen tube growth under culture conditions remain(s) largely unknown. Here, we report a previously unknown correlation between vacuolar function and the cell's ability to sustain mitochondrial functions in pear pollen tubes. The pear pollen tubes in vitro grew slowly after 15 hours post-cultured (HPC) and nearly ceased growth at 18 HPC. There was increased malondialdehyde content and membrane ion leakage at 15 HPC compared with 12 HPC. Furthermore, cytoplasmic acidification mainly mediated by decreased vacuolar H(+)-ATPase [V-ATPase, Enzyme Commission (EC) 3.6.1.3] activity was observed in pollen tubes after 15 HPC, and this further resulted in mitochondrial dysfunction, including mitochondrial structure disruption, mitochondrial membrane potential collapse and decreases in both oxygen consumption and ATP production. Our findings suggest that vacuoles and mitochondria intimately linked in regulating pollen tube elongation.

Apoplastic calmodulin promotes self-incompatibility pollen tube growth by enhancing calcium influx and reactive oxygen species concentration in Pyrus pyrifolia.

Calmodulin (CaM) has been associated with various physiological and developmental processes in plants, including pollen tube growth. In this study, we showed that CaM regulated the pear pollen tube growth in a concentration-dependent bi-phasic response. Using a whole-cell patch-clamp configuration, we showed that apoplastic CaM induced a hyperpolarization-activated calcium ion (Ca²âº) current, and anti-CaM largely inhibited this type of Ca²âº current. Moreover, upon anti-CaM treatment, the reactive oxygen species (ROS) concentration decreased and actin filaments depolymerized in the pollen tube. Interestingly, CaM could partially rescue the inhibition of self-incompatible pear pollen tube growth. This phenotype could be mediated by CaM-enhanced pollen plasma membrane Ca²âº current, tip-localized ROS concentration and stabilized actin filaments. These data indicated that Ca²âº, ROS and actin filaments were involved with CaM in regulating pollen tube growth and provide a potential way for overcoming pear self-incompatibility.

Self S-RNase reduces the expression of two pollen-specific COBRA genes to inhibit pollen tube growth in pear.

Due to self-incompatibility (SI) prevents self-fertilization, natural or artificial cross-pollination has been conducted in many orchards to stabilize fruit yield. However, it is still puzzled which routes of self S-RNase arresting pollen tube growth. Herein, 17 COBRA genes were isolated from pear genome. Of these genes, the pollen-specifically expressed PbCOB.A.1 and PbCOB.A.2 positively mediates pollen tube growth. The promoters of PbCOB.A.1 and/or PbCOB.A.2 were bound and activated by PbABF.E.2 (an ABRE-binding factor) and PbC2H2.K16.2 (a C2H2-type zinc finger protein). Notably, the expressions of PbCOB.A.1, PbCOB.A.2, and PbC2H2.K16.2 were repressed by self S-RNase, suggesting that self S-RNase reduces the expression of PbCOB.A.1 and PbCOB.A.2 by decreasing the expression of their upstream factors, such as PbC2H2.K16.2, to arrest pollen tube growth. PbCOB.A.1 or PbCOB.A.2 accelerates the growth of pollen tubes treated by self S-RNase, but can hardly affect level of reactive oxygen species and deploymerization of actin cytoskeleton in pollen tubes and cannot physically interact with any reported proteins involved in SI. These results indicate that PbCOB.A.1 and PbCOB.A.2 may not relieve S-RNase toxicity in incompatible pollen tube. The information provides a new route to elucidate the arresting pollen tube growth during SI reaction.

Fast loading ester fluorescent Ca2+ and pH indicators into pollen of Pyrus pyrifolia.

Loading of Ca(2+)-sensitive fluorescent probes into plant cells is an essential step to measure activities of free Ca(2+) ions in cytoplasm with a fluorescent imaging technique. Fluo-3 is one of the most suitable Ca(2+) indicators for CLSM. We loaded pollen with fluo-3/AM at three different temperatures. Fluo-3/AM was successfully loaded into pollen at both low (4°C) and high (37°C) temperatures. However, high loading temperature was best suited for pollen, because germination rate of pollen and growth of pollen tubes were relatively little impaired and loading time was shortened. Moreover, Ca(2+) distribution increased in the three apertures of pollen after hydration and showed a Ca(2+) gradient, similar to the tip of growing pollen tubes. The same protocol can be used with the AM-forms of other fluorescent dyes for effective labeling. When loading BCECF-AM into pollen at high temperature, the pollen did not show a pH gradient after hydration. Ca(2+) activities and fluxes had the same periodicity as pollen germination, but pH did not show the same phase and mostly lagged behind. However, the clear zone was alkaline when pollen tube growth was slowed or stopped and turned acidic when growth recovered. It is likely that apical pH(i) regulated pollen tube growth.

Does marine environmental research meet the challenges of marine pollution induced by the COVID-19 pandemic? Comparison analysis before and during the pandemic based on bibliometrics.

The outbreak of the COVID-19 pandemic has brought enormous challenges to the global marine environment. Various responses to the COVID-19 pandemic have led to increased marine pollution. Has the COVID-19 pandemic affected marine pollution research? This work comprehensively reviewed marine pollution publications in the Web of Science database before and during the COVID-19 pandemic. Results show that the COVID-19 outbreak has influenced the marine pollution research by: (i) increasing the number of publications; (ii) reshaping different countries' roles in marine pollution research; (iii) altering the hotspots of marine pollution research. The ranking of countries with high productivity in the marine pollution research field changed, and developed economies are the dominant players both before and after the outbreak of the COVID-19 pandemic in this field. Other high-productivity countries, with the exception of China, have higher international cooperation rates in marine pollution research than those before the pandemic. Microplastic pollution has been the biggest challenge of marine pollution and has been aexplored in greater depth during the COVID-19 pandemic. Furthermore, the mining results of marine pollution publications show the mitigation of plastic pollution in the marine environment remains the main content requires future research. Finally, this paper puts forward corresponding suggestions for the reference of researchers and practitioners to improve the global ability to respond to the challenges posed by the pandemic to the marine environment.

Spermidine oxidase-derived H2O2 regulates pollen plasma membrane hyperpolarization-activated Ca(2+) -permeable channels and pollen tube growth.

Spermidine (Spd) has been correlated with various physiological and developmental processes in plants, including pollen tube growth. In this work, we show that Spd induces an increase in the cytosolic Ca(2+) concentration that accompanies pollen tube growth. Using the whole-cell patch clamp and outside-out single-channel patch clamp configurations, we show that exogenous Spd induces a hyperpolarization-activated Ca(2+) current: the addition of Spd cannot induce the channel open probability increase in excised outside-out patches, indicating that the effect of Spd in the induction of Ca(2+) currents is exerted via a second messenger. This messenger is hydrogen peroxide (H2O2), and is generated during Spd oxidation, a reaction mediated by polyamine oxidase (PAO). These reactive oxygen species trigger the opening of the hyperpolarization-activated Ca(2+) -permeable channels in pollen. To provide further evidence that PAO is in fact responsible for the effect of Spd on the Ca(2+) -permeable channels, two Arabidopsis mutants lacking expression of the peroxisomal-encoding AtPAO3 gene, were isolated and characterized. Pollen from these mutants was unable to induce the opening of the Ca(2+) -permeable channels in the presence of Spd, resulting in reduced pollen tube growth and seed number. However, a high Spd concentration triggers a Ca(2+) influx beyond the optimal, which has a deleterious effect. These findings strongly suggest that the Spd-derived H2O2 signals Ca(2+) influx, thereby regulating pollen tube growth.

Oxidized low density lipoproteins--do we know enough about them?

Since the discovery of oxidized low density lipoprotein (Ox-LDL), over 5,000 articles have appeared on the topic with over 400 articles appearing every year during the past decade. LDL contains esterified polyunsaturated fatty acid containing lipids, such as, phosphatidylcholine (PtdCho) and cholesterol esters (CE). Peroxidation of polyunsaturated fatty acid (PUFA) containing lipids has been known for a long time. Numerous studies have documented that peroxidized lipids as well as products derived from their decomposition, particularly aldehydes, have deleterious biological properties. This concept has been exemplified in the study of atherosclerosis. A plethora of in vitro and animal studies, as well as human epidemiological and correlatory studies, have supported the notion that oxidative processes and the formation of Ox-LDL might contribute to atherosclerosis. Yet the negative outcomes of human clinical trials with α-tocopherol and other antioxidants have convinced even staunch supporters of the hypothesis to take a step backwards and reconsider reasons of their failure and suggest alternative approaches. Ox-LDL is a complex mixture of numerous chemical entities, many of them are yet uncharacterized. Why and how it is formed or its nature in vivo is poorly understood. It is recognized by numerous cell surface receptors, which are ubiquitously expressed in many different cell types. These receptors might perform a variety of functions. In addition, components of Ox-LDL might also have favorable effects that are difficult to dissociate from its pathological effects. In this review, the nature of Ox-LDL and potential problems in inhibiting its formation are discussed.