Physiological Variables Influenced by 'Candidatus Liberibacter asiaticus' Infection in Two Citrus Species

'Candidatus Liberibacter asiaticus' is the bacterium associated with the citrus disease known as huanglongbing (HLB). This study evaluated the influence of 'Ca. L. asiaticus' infection on a number of key plant physiological variables concerning photosynthesis, cell integrity, reactive oxygen species scavengers' activity, and osmoregulation of two different species of citrus-the pomelo Citrus maxima and the mandarin C. reticulata 'Tankan'-relative to their measured 'Ca. L. asiaticus' infection load. Results indicated that all measured physiological variables except soluble sugar were affected by increased 'Ca. L. asiaticus' infection titers, wherein the variety C. maxima proved overall more resistant than C. reticulata. 'Ca. L. asiaticus' infection was linked in both plants to decrease in chlorophyll concentration, cell membrane permeability, and malondialdehyde, as well as increased free proline and starch contents. Chlorophyll fluorescence measurements taken 9 months after grafting the mandarin C. reticulata with 'Ca. L. asiaticus' scions revealed a significant decrease in the photosynthesis variables maximum photochemical quantum yield of photosystem II (PSII), effective photochemical quantum yield of PSII, and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae, whereas nonphotochemical fluorescence quenching increased significantly; C. maxima plants, on the other hand, did not show significant differences until the 12th month from infection exposure. The variables superoxide dismutase, catalase, peroxidase, and soluble protein initially increased and later decreased. In addition, progression of 'Ca. L. asiaticus' replication in both citrus species was accompanied by rapid changes in three reactive oxygen species scavenging enzymes in C. maxima, while the pattern was different in C. reticulata. We hypothesize that the observed interspecific differences in physiological change are related to their relative resistance against 'Ca. L. asiaticus' infection. These results provide a scaffold for better describing the pathogenesis, selecting the most resistant breeds, or even validating pertaining omics research; ultimately, these detailed observations can facilitate the diagnosis of 'Ca. L. asiaticus' infection.

Effect of Monocerin, a Fungal Secondary Metabolite, on Endothelial Cells

This study reports the isolation and identification of the endophytic fungus Exserohilum rostratum through molecular and morphological analysis using optical and transmission electron microscopy (TEM), as well as the procurement of its secondary metabolite monocerin, an isocoumarin derivative. Considering the previously observed biological activities of monocerin, this study was performed on human umbilical vein endothelial cells (HUVECs) that are widely used as an in vitro model for several different purposes. Important parameters, such as cell viability, senescence-associated β-galactosidase, cellular proliferation by using 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE), apoptosis analysis with annexin, cellular morphology through scanning electron microscopy (SEM), and laser confocal analysis were evaluated after exposing the cells to monocerin. After 24 h of exposure to monocerin at 1.25 mM, there was more than 80% of cell viability and a low percentage of cells in the early and late apoptosis and necrosis. Monocerin increased cell proliferation and did not induce cell senescence. Morphological analysis showed cellular integrity. The study demonstrates aspects of the mechanism of action of monocerin on endothelial cell proliferation, suggesting the possibility of its pharmaceutical application, such as in regenerative medicine.

Effect of different priming fluids on extravascular lung water, cell integrity and oxidative stress in cardiopulmonary bypass surgery

BACKGROUND

Discussions continue on the ideal priming fluid in adult cardiac surgery. The purpose of this prospective study was to evaluate the effects of different types of priming fluids on extravascular lung water, cell integrity and oxidative stress status.

METHODS

Thirty elective coronary artery bypass surgery patients were randomised prospectively into two groups. The first group received colloid priming fluid, while the second group received crystalloid priming fluid. Extravascular lung water index, advanced oxidative protein products, total thiol, free haemoglobin, ischaemic modified albumin and sialic acid levels were measured. Moreover, intra-operative and postoperative outcomes were reviewed.

RESULTS

There were no significant differences between the groups with regard to extravascular lung water index, oxidative stress parameters or cell integrity (p > 0.05). Similarly, no significant differences were observed between the patients with regard to intra-operative and postoperative outcomes (p > 0.05).

CONCLUSIONS

The presumed superiority of colloidal priming for cardiopulmonary bypass could not be confirmed in our study.

Echinocandin Drugs Induce Differential Effects in Cytokinesis Progression and Cell Integrity

Fission yeast contains three essential β(1,3)-D-glucan synthases (GSs), Bgs1, Bgs3, and Bgs4, with non-overlapping roles in cell integrity and morphogenesis. Only the bgs4⁺ mutants pbr1-8 and pbr1-6 exhibit resistance to GS inhibitors, even in the presence of the wild-type (WT) sequences of bgs1⁺ and bgs3⁺. Thus, Bgs1 and Bgs3 functions seem to be unaffected by those GS inhibitors. To learn more about echinocandins' mechanism of action and resistance, cytokinesis progression and cell death were examined by time-lapse fluorescence microscopy in WT and pbr1-8 cells at the start of treatment with sublethal and lethal concentrations of anidulafungin, caspofungin, and micafungin. In WT, sublethal concentrations of the three drugs caused abundant cell death that was either suppressed (anidulafungin and micafungin) or greatly reduced (caspofungin) in pbr1-8 cells. Interestingly, the lethal concentrations induced differential phenotypes depending on the echinocandin used. Anidulafungin and caspofungin were mostly fungistatic, heavily impairing cytokinesis progression in both WT and pbr1-8. As with sublethal concentrations, lethal concentrations of micafungin were primarily fungicidal in WT cells, causing cell lysis without impairing cytokinesis. The lytic phenotype was suppressed again in pbr1-8 cells. Our results suggest that micafungin always exerts its fungicidal effect by solely inhibiting Bgs4. In contrast, lethal concentrations of anidulafungin and caspofungin cause an early cytokinesis arrest, probably by the combined inhibition of several GSs.

The Role of the Cell Integrity Pathway in Septum Assembly in Yeast

Cytokinesis divides a mother cell into two daughter cells at the end of each cell cycle and proceeds via the assembly and constriction of a contractile actomyosin ring (CAR). Ring constriction promotes division furrow ingression, after sister chromatids are segregated to opposing sides of the cleavage plane. Cytokinesis contributes to genome integrity because the cells that fail to complete cytokinesis often reduplicate their chromosomes. While in animal cells, the last steps of cytokinesis involve extracellular matrix remodelling and mid-body abscission, in yeast, CAR constriction is coupled to the synthesis of a polysaccharide septum. To preserve cell integrity during cytokinesis, fungal cells remodel their cell wall through signalling pathways that connect receptors to downstream effectors, initiating a cascade of biological signals. One of the best-studied signalling pathways is the cell wall integrity pathway (CWI) of the budding yeast Saccharomyces cerevisiae and its counterpart in the fission yeast Schizosaccharomyces pombe, the cell integrity pathway (CIP). Both are signal transduction pathways relying upon a cascade of MAP kinases. However, despite strong similarities in the assembly of the septa in both yeasts, there are significant mechanistic differences, including the relationship of this process with the cell integrity signalling pathways.

Evaluating the effects of microparticle addition on mycelial morphology, natural yellow pigments productivity, and key genes regulation in submerged fermentation of Monascus purpureus

Morphology plays an important role in fungal fermentation and secondary metabolites biosynthesis. One novel technique, microparticle-enhanced cultivation was successfully utilized to control the morphology of Monascus purpureus precisely and enhance the yield of yellow pigments. The production of yellow pigments increased to 554.2 U/ml when 4 g/L 5000 mesh talc added at 24 h. Field emission scanning electron microscope observation indicated that the actual effect depends on the properties of microparticle. Sharp-edged microparticles showed better stimulatory effects than smooth, round-shaped ones. Particle size analysis, scanning electron microscope, and cell integrity evaluation proved obvious morphological changes were induced by talc addition, including smaller mycelial size, rougher hyphae, and decreased cell integrity. Furthermore, the expression levels of MrpigG, MrpigD, MrpigE, and MrpigH were significantly upregulated by the addition of talc. It indicated that the microparticle could not only affect the mycelial morphology, but also influence the expression levels of key genes in biosynthetic pathway of Monascus yellow pigments.

Simultaneous Removal of Microcystis aeruginosa and 2,4,6-Trichlorophenol by UV/Persulfate Process

UV/persulfate (UV/PS) could effectively degrade algal cells and micro-organic pollutants. This process was firstly applied to remove Microcystis aeruginosa (M. aeruginosa) and 2,4,6-trichlorophenol (TCP) simultaneously in bench scale. Algal cells can be efficiently removed after 120 min reaction accompanied with far quicker removal of the coexisted TCP, which could be totally removed within 5 min in the UV/PS process. Both SO4•- and HO^• were responsible for algal cells and TCP degradation, while SO4•- and HO^• separately dominated TCP degradation and algal cells removal. Apart from the role of radicals (SO4•- and HO^•) for algal cells and TCP degradation, UV also played a role to some extent. Increased PS dose (0–4.5 mM) or UV intensity (2.71–7.82 mW/cm²) could enhance the performance of the UV/PS process in both TCP and algae removal. Although some intracellular organic matters can be released to the outside of algal cells due to the cell lysis, they can be further degraded by UV/PS process, which was inhibited by the presence of TCP. This study suggested the good potential of the UV/PS process in the simultaneous removal of algal cells and micro-organic pollutants.

Chirality of the biomolecules enhanced its stereospecific action of dihydromyricetin enantiomers

The present study explores the effect of chirality of the biological macromolecules, its functional aspects, and its interaction with other food components. Dihydromyricetin (DHM) is a natural novel flavonol isolated from the vine tea (Ampelopsis grossedentata) leaves. However, limited progress in enantiopure separation methods of such compounds hinder in the development of enantiopure functional studies. This study is an attempt to develop a simple, accurate, and sensitive extraction method for the separation of the enantiopure DHM from vine tea leaves. In addition, the identification and purity of the extracted enantiopure (-)-DHM were further determined by the proton nuclear magnetic resonance (1H-NMR) and the carbon nuclear magnetic resonance (13C-NMR). The study further evaluates the antimicrobial activity of isolated (-)-DHM in comparison with racemate (+)-DHM, against selected foodborne pathogens, whereas the action mode of enantiopure (-)-DHM to increase the integrity and permeability of the bacterial cell membrane was visualized by confocal laser scanning microscopy using green fluorescence nucleic acid dye (SYTO-9) and propidium iodide (PI). Moreover, the morphological changes in the bacterial cell structure were observed through field emission scanning electron microscope. During analyzing the cell morphology of B. cereus (AS11846), it was confirmed that enantiopure (-)-DHM could increase the cell permeability that leads to the released of internal cell constituents and, thus, causes cell death. Therefore, the present study provides an insight into the advancement of enantiopure isolation along with its antimicrobial effect which could be served as an effective approach of biosafety.

Effects of the cryopreservation process on dog sperm integrity

Sperm cryopreservation has become an indispensable tool in reproductive biology. However, frozen/thawed semen has a short lifespan due to loss of sperm cell integrity. To better understand which sperm cell structures are compromised by the cryopreservation process and apoptosis markers, the sperm of five healthy mature dogs was analyzed in this study. Analysis was performed after collection, cooling, and thawing via computer assisted sperm analyzer (CASA) and evaluation of membrane fluidity and permeability, phosphatidylserine translocation (Annexin V), membrane integrity, mitochondrial membrane potential, membrane lipid peroxidation (LPO) and activity of the apoptotic markers caspases 3 and 7 by flow cytometry. Cryopreservation decreased total and progressive motility and the percentage of rapid sperm (P < 0.01). Damage to sperm cells was confirmed by Annexin V (P < 0.01), indicating that capacitation-like changes were induced by the cryopreservation procedures. An increase in sperm membrane fluidity was also noted in frozen/thawed samples (P < 0.01). Plasma and acrosomal cell membranes were affected (P < 0.01), with decreases in the subpopulation displaying high membrane potential (P < 0.01). Membrane LPO was increased in thawed sperm compared to cooled sperm (P < 0.05) but was not different from that in fresh sperm. No differences were observed in caspase 3 and 7 activity after cooling, freezing, or thawing. In conclusion, total and progressive motility, plasma membrane integrity and mitochondrial membrane potential suffered from the deleterious effects caused by cryopreservation, unlike the activity of caspases that remained stable during the freezing process.

The Glucan-Remodeling Enzyme Phr1p and the Chitin Synthase Chs1p Cooperate to Maintain Proper Nuclear Segregation and Cell Integrity in Candida albicans

GH72 family of β-(1,3)-glucanosyltransferases is unique to fungi and is required for cell wall biogenesis, morphogenesis, virulence, and in some species is essential for life. Candida albicans PHR1 and PHR2 are pH-regulated genes that encode GH72 enzymes highly similar to Gas1p of Saccharomyces cerevisiae. PHR1 is expressed at pH ≥ 5.5 while PHR2 is transcribed at pH ≤ 5.5. Both are essential for C. albicans morphogenesis and virulence. During growth at neutral-alkaline pH, Phr1p-GFP preferentially localizes to sites of active cell wall formation as the incipient bud, the mother-daughter neck, the bud periphery, and concentrates in the septum at cytokinesis. We further investigated this latter localization. In chs3Δ cells, lacking the chitin of the chitin ring and lateral cell wall, Phr1p-GFP still concentrated along the thin line of the primary septum formed by chitin deposited by chitin synthase I (whose catalytic subunit is Chs1p) suggesting that it plays a role during formation of the secondary septa. RO-09-3143, a highly specific inhibitor of Chs1p activity, inhibits septum formation and blocks cell division. However, alternative septa are produced and are crucial for cell survival. Phr1p-GFP is excluded from such aberrant septa. Finally, we determined the effects of RO-09-3143 in cells lacking Phr1p. PHR1 null mutant was more susceptible to the drug than the wild type. The phr1Δ cells were larger, devoid of septa, and underwent endomitosis and cell death. Phr1p and Chs1p cooperate in maintaining cell integrity and in coupling morphogenesis with nuclear division in C. albicans.

Enhanced glycosylation of an S-layer protein enables a psychrophilic methanogenic archaeon to adapt to elevated temperatures in abundant substrates

Adaptation to higher temperatures would increase the environmental competitiveness of psychrophiles, organisms that thrive in low-temperature environments. Methanolobus psychrophilus, a cold wetland methanogen, 'evolved' as a mesophile, growing optimally at 30 °C after subculturings, and cells grown with ample substrates exhibited higher integrity. Here, we investigated N-glycosylation of S-layer proteins, the major archaeal envelope component, with respect to mesophilic adaptation. Lectin affinity enriched a glycoprotein in cells grown at 30 °C under ample substrate availability, which was identified as the S-layer protein Mpsy_1486. Four N-glycosylation sites were identified on Mpsy_1486, which exhibited different glycosylation profiles, with N94 only found in cells cultured at 30 °C. An N-linked glycosylation inhibitor, tunicamycin, reduced glycosylation levels of Mpsy_1486 and growth at 30 °C, thus establishing a link between S-layer protein glycosylation and higher temperature adaptation of the psychrophilic archaeon M. psychrophilus.

Effects of Essential Oil Citral on the Growth, Mycotoxin Biosynthesis and Transcriptomic Profile of Alternaria alternata

Alternaria alternata is a critical phytopathogen that causes foodborne spoilage and produces a polyketide mycotoxin, alternariol (AOH), and its derivative, alternariol monomethyl ether (AME). In this study, the inhibitory effects of the essential oil citral on the fungal growth and mycotoxin production of A. alternata were evaluated. Our findings indicated that 0.25 μL/mL (222.5 μg/mL) of citral completely suppressed mycelial growth as the minimum inhibitory concentration (MIC). Moreover, the 1/2MIC of citral could inhibit more than 97% of the mycotoxin amount. Transcriptomic profiling was performed by comparative RNA-Seq analysis of A. alternata with or without citral treatment. Out of a total of 1334 differentially expressed genes (DEGs), 621 up-regulated and 713 down-regulated genes were identified under citral stress conditions. Numerous DEGs for cell survival, involved in ribosome and nucleolus biogenesis, RNA processing and metabolic processes, and protein processing, were highly expressed in response to citral. However, a number of DEGs responsible for the metabolism of several carbohydrates and amino acids, sulfate and glutathione metabolism, the metabolism of xenobiotics and transporter activity were significantly more likely to be down-regulated. Citral induced the disturbance of cell integrity through the disorder of gene expression, which was further confirmed by the fact that exposure to citral caused irreversibly deleterious disruption of fungal spores and the inhibition of ergosterol biosynthesis. Citral perturbed the balance of oxidative stress, which was likewise verified by a reduction of total antioxidative capacity. In addition, citral was able to modulate the down-regulation of mycotoxin biosynthetic genes, including pksI and omtI. The results provide new insights for exploring inhibitory mechanisms and indicate citral as a potential antifungal and antimytoxigenic alternative for cereal storage.

Sperm head abnormalities are more frequent in songbirds with more helical sperm: A possible trade-off in sperm evolution

Sperm morphology varies enormously across the animal kingdom. Whilst knowledge of the factors that drive the evolution of interspecific variation in sperm morphology is accumulating, we currently have little understanding of factors that may constrain evolutionary change in sperm traits. We investigated whether susceptibility to sperm abnormalities could represent such a constraint in songbirds, a group characterized by a distinctive helical sperm head shape. Specifically, using 36 songbird species and data from light and scanning electron microscopy, we examined among-species correlations between the occurrence of sperm head abnormalities and sperm morphology, as well as the correlation between sperm head abnormalities and two indicators of sperm competition. We found that species with more helically shaped sperm heads (i.e., a wider helical membrane and more pronounced cell waveform) had a higher percentage of abnormal sperm heads than species with less helical sperm (i.e., relatively straight sperm) and that sperm head traits were better predictors of head abnormalities than total sperm length. In contrast, there was no correlation between sperm abnormalities and the level of sperm competition. Given that songbird species with more pronounced helical sperm have higher average sperm swimming speed, our results suggest an evolutionary trade-off between sperm performance and the structural integrity of the sperm head. As such, susceptibility to morphological abnormalities may constrain the evolution of helical sperm morphology in songbirds.

Effects of Peach Cultivar on Enzymatic Browning Following Cell Damage from High-Pressure Processing

Peach cultivars contribute to unique product characteristics and may affect the degree of browning after high-pressure processing (HPP). Nine peach cultivars were subjected to HPP at 0, 100, and 400 MPa for 10 min. Proton nuclear magnetic resonance (¹H NMR) relaxometry, light microscopy, color, polyphenol oxidase (PPO) activity, and total phenols were evaluated. The development of enzymatic browning during refrigerated storage occurred because of damage during HPP that triggered loss of cell integrity, allowing substrates to interact with enzymes. Increasing pressure levels resulted in greater damage, as determined by shifts in transverse relaxation time (T₂) and by light micrographs. Discoloration was triggered by membrane decompartmentalization but limited by PPO activity, which was found to correlate to cultivar harvest time (early, mid, and late season). Outcomes from the microstructure, ¹H NMR ,and PPO activity evaluation were an effective means of determining membrane decompartmentalization and allowed for prediction of browning scenarios.

Benzothiadiazole-Mediated Induced Resistance to Colletotrichum musae and Delayed Ripening of Harvested Banana Fruit

Benzothiadiazole (BTH) works as a plant activator. The effects of different BTH treatments and fungicides SPORGON on fruit ripening and disease incidence were investigated. The results showed that BTH treatment significantly delayed fruit ripening, maintained fruit firmness, color, and good fruit quality, and dramatically reduced the incidence of disease. BTH effectively inhibited the invasion and development of pathogenic bacteria and controlled the occurrence of disease. BTH treatment enhanced the activities of defense-related enzymes, including chitinase, phenylalanine ammonia-lyase, peroxidase, and polyphenol oxidase, increased the content of hydrogen peroxide and total antioxidant capacity, and reduced malondialdehyde content. Cellular structure analysis after inoculation confirmed that BTH treatment effectively maintained the cell structural integrity. SPORGON did not provide benefits for delaying fruit ripening or for the resistance system, while it can control the disease only during the earlier stage and not at later stages.

The fate of Microcystis aeruginosa cells during the ferric chloride coagulation and flocs storage processes

Microcystis blooms could cause severe problems for drinking water supplies with their associated microcystins (MCs). As the majority of MCs are retained inside the cells, the effective removal of the intact Microcystis cells to avoid the release of additional MCs plays an important role in drinking water treatment. This study evaluated the effect of ferric chloride (FeCl3) coagulation and the flocs storage process on the integrity of Microcystis aeruginosa cells and the intracellular MCs release (and possible degradation) in both processes. Multiple analysis techniques including scanning electron microscopy and chlorophyll fluorescence were used to assess the integrity of M. aeruginosa. In the coagulation process, the coagulant dosage and mechanical actions caused no cell damage, and all the cells remained intact. Furthermore, 100 mg/L FeCl3 was effective in removing the extracellular MCs. In the flocs storage process, a number of intracellular MCs were released into the supernatant, but the cells remained viable up to 10 d.

Negative functional interaction between cell integrity MAPK pathway and Rho1 GTPase in fission yeast

Rho1 GTPase is the main activator of cell wall glucan biosynthesis and regulates actin cytoskeleton in fungi, including Schizosaccharomyces pombe. We have obtained a fission yeast thermosensitive mutant strain carrying the rho1-596 allele, which displays reduced Rho1 GTPase activity. This strain has severe cell wall defects and a thermosensitive growth, which is partially suppressed by osmotic stabilization. In a global screening for rho1-596 multicopy suppresors the pmp1+ gene was identified. Pmp1 is a dual specificity phosphatase that negatively regulates the Pmk1 mitogen-activated protein kinase (MAPK) cell integrity pathway. Accordingly, elimination of Pmk1 MAPK partially rescued rho1-596 thermosensitivity, corroborating the unexpected antagonistic functional relationship of these genes. We found that rho1-596 cells displayed increased basal activation of the cell integrity MAPK pathway and therefore were hypersensitive to MgCl2 and FK506. Moreover, the absence of calcineurin was lethal for rho1-596. We found a higher level of calcineurin activity in rho1-596 than in wild-type cells, and overexpression of constitutively active calcineurin partially rescued rho1-596 thermosensitivity. All together our results suggest that loss of Rho1 function causes an increase in the cell integrity MAPK activity, which is detrimental to the cells and turns calcineurin activity essential.

Cdc42 regulation of polarized traffic in fission yeast

Cdc42 is a key factor in the control of cell polarity and morphogenesis. Fission yeast Cdc42 regulates formin activation and actin cable assembly. Cdc42 is also required for exocyst function, contributing to polarized secretion. Additionally, Cdc42 participates in membrane trafficking, endosome recycling, and vacuole formation. We show here how Cdc42 is required for the correct transport/recycling to the plasma membrane of the glucan synthases Bgs1 and Bgs4, responsible of cell wall biosynthesis and polarized growth at the cell tips.