Deciphering the molecular basis for photosynthetic parameters in Bambara groundnut (Vigna subterranea L. Verdc) under drought stress.

BACKGROUND: Assessment of segregating populations for their ability to withstand drought stress conditions is one of the best approaches to develop breeding lines and drought tolerant varieties. Bambara groundnut (Vigna subterranea L. Verdc.) is a leguminous crop, capable of growing in low-input agricultural systems in semi-arid areas. An F4 bi-parental segregating population obtained from S19-3 × DodR was developed to evaluate the effect of drought stress on photosynthetic parameters and identify QTLs associated with these traits under drought-stressed and well-watered conditions in a rainout shelter. RESULTS: Stomatal conductance (gs), photosynthesis rate (A), transpiration rate (E) and intracellular CO2 (Ci) were significantly reduced (p < 0.05) while water use efficiency (WUE) was significantly increased (p < 0.05) under drought-stressed conditions. A strong linear correlation was observed between gs, WUE, A, E and Ci under both water regimes. The variability between different water treatment, among individual lines and the interaction between lines and environment for photosynthetic parameters provides resources for superior lines selection and drought resistant variety improvement. Significant QTL for gs and FV/FM under well-watered conditions were mapped on LG5 and LG3, respectively, with more than 20% of the PVE, which could be considered as the major QTL to control these traits. Five clustered QTLs for photosynthetic traits under drought-stressed and well-watered conditions were mapped on LG5, LG6A, LG10 and LG11, respectively. CONCLUSIONS: Significant and putative QTLs associated with photosynthetic parameters and the effect of drought stress on these traits have been revealed by QTL linkage mapping and field experiment in the F4 segregating population derived from S19-3 × DodR in bambara groundnut. The study provides fundamental knowledge of how photosynthetic traits response to drought stress and how genetic features control these traits under drought-stressed and well-watered conditions in bambara groundnut.

De novo chromosome-level genome of a semi-dwarf cultivar of Prunus persica identifies the aquaporin PpTIP2 as responsible for temperature-sensitive semi-dwarf trait and PpB3-1 for flower type and size.

Peach (Prunus persica) is one of the most important fruit crops globally, but its cultivation can be hindered by large tree size. 'Zhongyoutao 14' (CN14) is a temperature-sensitive semi-dwarf (TSSD) cultivar which might be useful as breeding stock. The genome of CN14 was sequenced and assembled de novo using single-molecule real-time sequencing and chromosome conformation capture assembly. A high-quality genome was assembled and annotated, with 228.82 Mb mapped to eight chromosomes. Eighty-six re-sequenced F1 individuals and 334 previously re-sequenced accessions were used to identify candidate genes controlling TSSD and flower type and size. An aquaporin tonoplast intrinsic protein (PpTIP2) was a strong candidate gene for control of TSSD. Sequence variations in the upstream regulatory region of PpTIP2 correlated with different transcriptional activity at different temperatures. PpB3-1, a candidate gene for flower type (SH) and flower size, contributed to petal development and promoted petal enlargement. The locus of another 12 agronomic traits was identified through genome-wide association study. Most of these loci exhibited consistent and precise association signals, except for flesh texture and flesh adhesion. A 6015-bp insertion in exon 3 and a 26-bp insertion upstream of PpMYB25 were associated with fruit hairless. Along with a 70.5-Kb gap at the F-M locus in CN14, another two new alleles were identified in peach accessions. Our findings will not only promote genomic research and agronomic breeding in peach but also provide a foundation for the peach pan-genome.

My time with Franz Enzinger at the Armed Forces Institute of Pathology.

By a set of curious chances, Dr. F.M.Enzinger went from being captured as a prisoner of war by the American Army in Normandy in 1944 to become Head of the Soft Tissue Department of the Armed Forces Institute of Pathology (AFIP) in Washington DC and a friend of one of the directors, Major General Joe M. Blumberg. The author relates how he worked under Enzinger from 1967 to 1970. Enzinger would review all the slides of referred consultation cases on alternate days and record his diagnoses on filing cards kept in his personal file which supplemented the computerised AFIP central file. Periodic reviews of the files allowed him to retrieve large numbers of recognised tumors and to study potential cases of previously undescribed entities. During his 31 years at the AFIP, Enzinger lectured widely, wrote numerous papers on recognised entities, co-authored with Dr. Sharon W. Weiss their famous text book and discovered the following 26 previously undefined soft tissue tumors: clear cell sarcoma, intramuscular myxoma, epithelioid sarcoma, extra-skeletal myxoid chondrosarcoma, fetal rhabdomyoma, extra-skeletal Ewing's sarcoma, spindle cell lipoma, fibroma of tendon sheath, angiomatoid (malignant) fibrous histiocytoma, cranial fasciitis of childhood, intravascular fasciitis, pleomorphic lipoma, neuromuscular hamartoma, epithelioid hemangioendothelioma, spindle cell hemangioma, fibro-osseous pseudotumor of the digits, plexiform fibrohistiocytic tumor, giant cell fibroblastoma as a juvenile form of dermatofibrosarcoma protuberans, ossifying fibromyxoid tumor, myolipoma of soft tissues, inflammatory fibrosarcoma, juxta-articular myxoma, atypical decubital fibroplasia, chondroid lipoma, sclerosing epithelioid fibrosarcoma, and lipofibromatosis. His last discovery, co-authored by some of his AFIP followers, was published in 2000. He died in 2006. The AFIP itself was "disestablished" only five years later, which will make it very difficult for any future pathologist to exceed Enzinger's astonishing record of 26 "new" tumor discoveries.

Methylobacterium oryzae CBMB20 influences photosynthetic traits, volatile emission and ethylene metabolism in Oryza sativa genotypes grown in salt stress conditions.

MAIN CONCLUSION: Inoculation of endophytic Methylobacterium oryzae CBMB20 in salt-stressed rice plants improves photosynthesis and reduces stress volatile emissions due to mellowing of ethylene-dependent responses and activating vacuolar H+-ATPase. The objective of this study was to analyze the impact of ACC (1-aminocyclopropane-1-carboxylate) deaminase-producing Methylobacterium oryzae CBMB20 in acclimation of plant to salt stress by controlling photosynthetic characteristics and volatile emission in salt-sensitive (IR29) and moderately salt-resistant (FL478) rice (Oryza sativa L.) cultivars. Saline levels of 50 mM and 100 mM NaCl with and without bacteria inoculation were applied, and the temporal changes in stress response and salinity resistance were assessed by monitoring photosynthetic characteristics, ACC accumulation, ACC oxidase activity (ACO), vacuolar H+ ATPase activity, and volatile organic compound (VOC) emissions. Salt stress considerably reduced photosynthetic rate, stomatal conductance, PSII efficiency and vacuolar H+ ATPase activity, but it increased ACC accumulation, ACO activity, green leaf volatiles, mono- and sesquiterpenes, and other stress volatiles. These responses were enhanced with increasing salt stress and time. However, rice cultivars treated with CBMB20 showed improved plant vacuolar H+ ATPase activity, photosynthetic characteristics and decreased ACC accumulation, ACO activity and VOC emission. The bacteria-dependent changes were greater in the IR29 cultivar. These results indicate that decreasing photosynthesis and vacuolar H+ ATPase activity rates and increasing VOC emission rates in response to high-salinity stress were effectively mitigated by M. oryzae CBMB20 inoculation.

Lamelloplasts and minichloroplasts in Begoniaceae: iridescence and photosynthetic functioning.

Iridoplasts (modified plastids in adaxial epidermal cells) reported from Begonia were originally hypothesized to cause iridescence, which was broadly accepted for decades. However, several species of Begonia with iridoplasts are not iridescent causing confusion. Here chloroplast ultrastructure was observed in 40 taxa of Begoniaceae to explore the phenomenon of iridescence. However, 22 Begonias and Hillebrandia were found to have iridoplasts, but only nine display visually iridescent blue to blue-green leaves. Unexpectedly, a new type of plastid, a 'minichloroplast,' was found in the abaxial epidermal cells of all taxa, but was present in adaxial epidermal cells only if iridoplasts were absent. Comparative ultrastructural study of iridoplasts and a shading experiment of selected taxa show that a taxon with iridoplasts does not inevitably have visual iridescence, but iridescence is greatly affected by the spacing between thylakoid lamellae (stoma spacing). Thus, we propose instead the name 'lamelloplast' for plastids filled entirely with regular lamellae to avoid prejudging their function. To evaluate photosynthetic performance, chlorophyll fluorescence (F v /F m ) was measured separately from the chloroplasts in the adaxial epidermis and lower leaf tissues by using leaf dermal peels. Lamelloplasts and minichloroplasts have much lower photosynthetic efficiency than mesophyll chloroplasts. Nevertheless, photosynthetic proteins (psbA protein of PSII, RuBisCo and ATPase) were detected in both plastids as well as mesophyll chloroplasts in an immunogold labeling. Spectrometry revealed additional blue to blue-green peaks in visually iridescent leaves. Micro-spectrometry detected a blue peak from single blue spots in adaxial epidermal cells confirming that the color is derived from lamelloplasts. Presence of lamelloplasts or minichloroplasts is species specific and exclusive. High prevalence of lamelloplasts in Begoniaceae, including the basal clade Hillebrandia, highlights a unique evolutionary development. These new findings clarify the association between iridescence and lamelloplasts, and with implications for new directions in the study of plastid morphogenesis.

Impact of particulate matter accumulation on the photosynthetic apparatus of roadside woody plants growing in the urban conditions.

Particulate matter (PM) is one of the most harmful inhaled pollutants. When pollutants are emitted into the atmosphere, the only possible method for cleaning the air is through phytoremediation, where plants act as biological filters for pollutants. However, PM also has negative impacts on plants, although knowledge concerning the effects of PM on vegetation remains limited. In this work, an attempt was therefore made to define the amount of PM and waxes on foliage, and to evaluate the efficiency of the photosynthetic apparatus in seven plant species (three trees, three shrubs and one climber) grown in two locations (centre and suburbs of Warsaw) that differed in their level of PM pollution in the air. More PM and waxes accumulated on the foliage of plants grown in the highly polluted location. These plants also exhibited a lowered efficiency of their photosynthetic apparatus, manifested by a lower photosynthesis rate that corresponded with an increased stomatal resistance. Plants grown in the more polluted environment also showed decreased values of Fv/Fm parameter and no statistically significant trend to increase total chlorophyll content. Among the tested species, Betula pendula Roth accumulated the greatest amount of PM and Physocarpus opulifolius L. showed no weakening of its parameters of photosynthesis in a more contaminated environment.

The bamboo aquaporin gene PeTIP4;1-1 confers drought and salinity tolerance in transgenic Arabidopsis.

KEY MESSAGE: PeTIP4;1-1, an aquaporin gene involved in bamboo shoot growth, is regulated by abiotic stresses. Overexpression of PeTIP4;1-1 confers drought and salinity tolerance in transgenic Arabidopsis. Aquaporins play a central role in numerous physiological processes throughout plant growth and development. PeTIP4;1-1, an aquaporin gene isolated from moso bamboo (Phyllostachys edulis), comprises an open reading frame (ORF) of 756 bp encoding a peptide of 251 amino acids. The genomic sequence corresponding to the ORF of PeTIP4;1-1 was 1777 bp and contained three exons separated by two introns. PeTIP4;1-1 was constitutively expressed at the highest level in culms, and the expression level was elevated with increasing height of the bamboo shoot. PeTIP4;1-1 was significantly up-regulated in response to drought and salinity stresses in bamboo roots and leaves. To investigate the role of PeTIP4;1-1 in response to drought and salinity stresses, transgenic Arabidopsis plants overexpressing PeTIP4;1-1 under the control of CaMV 35S promoter were generated and subjected to morphological and physiological assays. Compared with Col-0, the transgenic plants showed enhanced tolerance to drought and salinity stresses and produced longer taproots, which had more green leaves, higher F v/F m and NPQ values, higher activities of SOD, POD and CAT, lower MDA concentration and higher water content. Transcript levels of three stress-related genes (AtP5CS, AtNHX1 and AtLEA) were enhanced. These results indicated that PeTIP4;1-1 might play an important function in response to drought and salinity stresses, and is a candidate gene for breeding of stress tolerance in other crops through genetic engineering.

Chlorophyll fluorescence imaging as a tool to monitor the progress of a root pathogen in a perennial plant.

MAIN CONCLUSION: The chlorophyll fluorescence parameter ΦNO is an excellent metric for the non-destructive monitoring of disease progression, measured over a broad range of light intensities. The suitability of the slow induction chlorophyll fluorescence parameters ΦPSII, ΦNPQ, and ΦNO to monitor in vivo disease progression in a host-root pathogen pathosystem was evaluated and compared to the established method of monitoring disease by measuring Fv/Fm. Using the infection of ginseng plants (Panax quinquefolius L.) with Pythium irregulare Buisman as a model, light response curves were used to establish the optimal irradiance for the resolution of differences between fluorescence parameters ΦPSII, ΦNPQ and ΦNO. As infection progressed only changes in ΦNO remained consistent with increased irradiance, and increased as infection progressed. Furthermore, ΦNO showed a high sensitivity for distinguishing increased disease load. In contrast, the magnitude in change of ΦPSII and ΦNPQ were sensitive to irradiance levels. The magnitude of increase in ΦNO per unit disease score was equivalent to the corresponding decline in Fv/Fm values. Thus ΦNO is as sensitive as Fv/Fm in monitoring biotic stress. The ability to measure ΦNO under a wide range of light intensities, including natural light, potentially without the need for dark adaptation, means that it can be used in the development of a general protocol for non-invasive, in vivo monitoring of plant health, from the laboratory to the field scale.

Characterization and primary functional analysis of a bamboo NAC gene targeted by miR164b.

KEY MESSAGE: PeSNAC1 , a stress-related NAC1 from Phyllostachys edulis , was characterized. Ectopic expression in Arabidopsis indicated that PeSNAC1 together with ped -miR164b participated in the regulation of organ boundaries and stress tolerance. NAC (NAM, ATAF1/2 and CUC2) participates in many different processes regulating plant growth, development, and stress response. A total of 125 NAC genes have been predicted in moso bamboo (Phyllostachys edulis), but their roles are poorly understood. PeSNAC1 targeted by ped-miR164b was focused for further study. The cleavage of PeSNAC1 mRNA guided by ped-miR164b was validated using RLM-5' RACE. Tissue-specific expression analysis demonstrated that ped-miR164b had a declining trend from root, sheath, leaf, to that of stem, which was opposite to that of PeSNAC1. Transgenic Arabidopsis plants overexpressing either PeSNAC1 (OX-PeSNAC1) or, ped-miR164b (OX-ped-miR164b) driven by the CaMV35S promoter were generated. OX-ped-miR164b plants showed similar phenotype of cuc2 mutants whose growth was seriously suppressed. Compared with Col-0, sense OX-PeSNAC1 plants grew rapidly and flowered earlier, whereas antisense plants grew slowly and exhibited delayed flowering. Sense OX-PeSNAC1 plants had the greatest number of lateral roots, while antisense OX-PeSNAC1 and OX-ped-miR164b plants had fewer lateral roots than Col-0. Under NaCl and PEG6000 stresses, survival rates were higher and F v/F m values declined more slowly in sense OX-PeSNAC1 plants than in Col-0, with lower survival rates and a more rapid decrease in F v/F m values conversely observed in antisense OX-PeSNAC1 and OX-ped-miR164b plants. These findings indicated that ped-miR164b-targeted PeSNAC1 may play key roles in plant development and tolerance to salinity and drought stresses.

Towards an integrated phylogenetic classification of the Tremellomycetes.

Families and genera assigned to Tremellomycetes have been mainly circumscribed by morphology and for the yeasts also by biochemical and physiological characteristics. This phenotype-based classification is largely in conflict with molecular phylogenetic analyses. Here a phylogenetic classification framework for the Tremellomycetes is proposed based on the results of phylogenetic analyses from a seven-genes dataset covering the majority of tremellomycetous yeasts and closely related filamentous taxa. Circumscriptions of the taxonomic units at the order, family and genus levels recognised were quantitatively assessed using the phylogenetic rank boundary optimisation (PRBO) and modified general mixed Yule coalescent (GMYC) tests. In addition, a comprehensive phylogenetic analysis on an expanded LSU rRNA (D1/D2 domains) gene sequence dataset covering as many as available teleomorphic and filamentous taxa within Tremellomycetes was performed to investigate the relationships between yeasts and filamentous taxa and to examine the stability of undersampled clades. Based on the results inferred from molecular data and morphological and physiochemical features, we propose an updated classification for the Tremellomycetes. We accept five orders, 17 families and 54 genera, including seven new families and 18 new genera. In addition, seven families and 17 genera are emended and one new species name and 185 new combinations are proposed. We propose to use the term pro tempore or pro tem. in abbreviation to indicate the species names that are temporarily maintained.

Effect of feed to microbe ratios on anaerobic digestion of Chinese cabbage waste under mesophilic and thermophilic conditions: biogas potential and kinetic study.

The objective of this study was to investigate the effect of the feed-to-microbe (F/M) ratios on anaerobic digestion of Chinese cabbage waste (CCW) generated from a kimchi factory. The batch test was conducted for 96 days under mesophilic (36.5 °C) (Experiment I) and thermophilic (55 °C) conditions (Experiment II) at F/M ratios of 0.5, 1.0 and 2.0. The first-order kinetic model was evaluated for methane yield. The biogas yield in terms of volatile solids (VS) added increased from 591 to 677 mL/g VS under mesophilic conditions and 434 to 639 mL/g VS under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. Similarly, the volumetric biogas production increased from 1.479 to 6.771 L/L under mesophilic conditions and from 1.086 to 6.384 L/L under thermophilic conditions when F/M ratio increased from 0.5 to 2.0. The VS removal increased from 59.4 to 75.6% under mesophilic conditions and from 63.5 to 78.3% under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. The first-order kinetic constant (k, 1/day) decreased under the mesophilic temperature conditions and increased under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. The difference between the experimental and predicted methane yield was in the range of 3.4-14.5% under mesophilic conditions and in the range of 1.1-3.0% under thermophilic conditions. The predicted methane yield derived from the first-order kinetic model was in good agreement with the experimental results.

Effects of transpalatal arch wire dimension and temporary skeletal anchorage device position on maxillary molar intrusion.

OBJECTIVES: To investigate the effects of transpalatal (TPA) wire dimension and temporary skeletal anchorage device (TSAD) position on maxillary molar intrusion. MATERIALS AND METHODS: The maxillary molar intrusion measurement system included a maxillary acrylic model, TPA, TSADs, and a three-dimensional Force/Moment (F/M) sensor. The intrusion patterns were categorized into six groups: buccal-mesial, buccal-distal, buccal-mesiodistal, palatal-mesial, palatal-distal, and palatal-mesiodistal. TPA wire dimensions were designed to be 0.7 mm, 0.9 mm, and 1.2 mm. The force and moment loads of the maxillary first molar were measured by the F/M sensor. RESULTS: Single buccal or palatal TSADs induced torquing movement, and single mesial or distal TSADs tended to promote tipping movement. Mesiodistal TSADs would have eliminated tipping, but accentuated torquing movement. The TPA significantly reduced the force and moment experienced by the maxillary first molar along three-dimensional axes. The thicker the TPA wire, the smaller the force and moment to which the maxillary first molar was subjected. CONCLUSIONS: Precise placement of TSADs might have a substantial influence on tooth movement and should be determined in accordance with specific clinical requirements. Increasing the TPA wire dimension could diminish the tipping, torquing, and rotation during TSAD-assisted maxillary molar intrusion, but these tendencies could not be completely eliminated.

Quantitative prediction of CYP3A induction-mediated drug-drug interactions in clinical practice.

There have been no reports on the quantitative prediction of CYP3A induction-mediated decreases in AUC and Cmax for drug candidates identified as a "victims" of CYP3A induction. Our previous study separately evaluated the fold-induction of hepatic and intestinal CYP3A by known inducers using clinical induction data and revealed that we were able to quantitatively predict the AUC ratio (AUCR) of a few CYP3A substrates in the presence and absence of CYP3A inducers. In the present study, we investigate the predictability of AUCR and also Cmax ratio (CmaxR) in additional 54 clinical studies. The fraction metabolized by CYP3A (fm), the intestinal bioavailability (Fg), and the hepatic intrinsic clearance (CLint) of substrates were determined by the in vitro experiments as well as clinical data used for calculating AUCR and CmaxR. The result showed that 65-69% and 65-67% of predictions were within 2-fold of observed AUCR and CmaxR, respectively. A simulation using multiple parameter combinations suggested that the variability of fm and Fg within a certain range might have a minimal impact on the calculation output. These findings suggest that clinical AUCR and CmaxR of CYP3A substrates can be quantitatively predicted from the preclinical stage.

Improving the Continuous Multiple Tube Reactor: an Innovative Bioreactor Configuration with Great Potential for Dark Fermentation Processes.

The continuous multiple tube reactor (CMTR) has been developed as a promising technology to maximize biohydrogen production (BHP) by dark fermentation (DF) by preventing excess biomass accumulation, leading to suboptimum values of specific organic loading rates (SOLR). However, previous experiences failed to achieve stable and continuous BHP in this reactor, as the low biomass retention capacity in the tube region limited controlling the SOLR. This study goes beyond the evaluation of the CMTR for DF by inserting grooves in the inner wall of the tubes to ensure better cell attachment. The CMTR was monitored in 4 assays at 25ºC using sucrose-based synthetic effluent. The hydraulic retention time (HRT) was fixed at 2 h, while the COD varied between 2-8 g L-1 to obtain organic loading rates in the 24 - 96 g COD L-1 d-1. Long-term (90 d) BHP was successfully attained in all conditions due to the improved biomass retention capacity. Optimal values for the SOLR (4.9 g COD g-1 VSS d-1) were observed when applying up to 48 g COD L-1 d-1, in which BHP was maximized. These patterns indicate a favorable balance between biomass retention and washout was naturally achieved. The CMTR looks promising for continuous BHP and is exempt from additional biomass discharge strategies.

Changes in spinal motoneuron excitability during the improvement of fingertip dexterity by actual execution combined with motor imagery practice.

Since there is an upper limit to skill improvement through the repetition of actual execution, we examined whether motor imagery could be used in combination with actual execution to maximize motor skill improvement. Fingertip dexterity was evaluated in 25 healthy participants performing a force adjustment task using a pinch movement with the left thumb and index finger. In the intervention condition, six sets of repetitions of combined actual execution and motor imagery were performed, while in the control condition, the same flow was performed, but with motor imagery replaced by rest. Changes in the excitability of spinal motoneurons during motor imagery compared to rest were compared in terms of the F/M amplitude ratio. Motor skill changes were compared before and after repeated practice and between the conditions, respectively, using the absolute amount of adjustment error between the target pinch force value and the delivered pinch force value (absolute error) as an index. The results showed that the repetition of exercise practice and motor imagery decreased the absolute error, which was greater than that of exercise practice alone in terms of motor skill improvement. The F/M amplitude ratio for motor imagery compared to rest did not increase. This suggests that motor imagery is involved in the degree of the increase of spinal motoneuron excitability based on the real-time prediction of motor execution and that there may be no need for an increase in excitability during motor skill control.

Influence of the cycle length on the production of PHA and polyglucose from glycerol by bacterial enrichments in sequencing batch reactors.

PHA, a naturally occurring biopolymer produced by a wide range of microorganisms, is known for its applications as bioplastic. In recent years the use of agro-industrial wastewater as substrate for PHA production by bacterial enrichments has attracted considerable research attention. Crude glycerol as generated during biodiesel production is a waste stream that due to its high organic matter content and low price could be an interesting substrate for PHA production. Previously we have demonstrated that when glycerol is used as substrate in a feast-famine regime, PHA and polyglucose are simultaneously produced as storage polymers. The work described in this paper aimed at understanding the effect of the cycle length on the bacterial enrichment process with emphasis on the distribution of glycerol towards PHA and polyglucose. Two sequencing batch reactors where operated with the same hydraulic and biomass retention time. A short cycle length (6 h) favored polyglucose production over PHA, whereas at long cycle length (24 h) PHA was more favored. In both communities the same microorganism appeared dominating, suggesting a metabolic rather than a microbial competition response. Moreover, the presence of ammonium during polymer accumulation did not influence the maximum amount of PHA that was attained.

Synchronization dynamics induced on pairs of neurons under applied weak alternating magnetic fields.

Pairs of Helix aspersa neurons show an alternating magnetic field dependent frequency synchronization (AMFS) when exposed to a weak (amplitude B0 between 0.2 and 150 Gauss (G)) alternating magnetic field (AMF) of extremely low frequency (ELF, fM = 50 Hz). We have compared the AMFS patterns of discharge with: i) the synaptic activity promoted by glutamate and acetylcholine; ii) the activity induced by caffeine; iii) the bioelectric activity induced on neurons interconnected by electric synapses. AMFS activity reveals several specific features: i) a tight coincidence in time of the pattern and frequency, f, of discharge; ii) it is induced in the time interval of field application; iii) it is dependent on the intensity of the sinusoidal applied magnetic field; iv) elicited biphasic responses (excitation followed by inhibition) run in parallel for the pair of neurons; and v) some neuron pairs either spontaneously or AMF synchronized can be desynchronized under applied higher AMF. Our electron microscopy studies reveal gap-like junctions confirming our immunocytochemistry results about expression of connexin 26 (Cx26) in 4.7% of Helix neurons. AMF and carbenoxolone did not induce any significant effect on spontaneous synchronization through electric synapses.

In hot water: Interactions of temperature, nitrogen form and availability and photosynthetic and nitrogen uptake responses in natural Karenia brevis populations.

During 2020-2021, an unusually prolonged bloom of the toxigenic dinoflagellate Karenia brevis persisted for more than 12 months along the Gulf coast of Florida, resulting in severe environmental effects. Motivated by the possibility that unusual nutrient conditions existed during summer 2021, the short-term interactions of temperature, nitrogen (N) forms (ammonium (NH4+), nitrate (NO3-), and urea) and availability on photosynthesis-irradiance responses and N uptake rates were examined in summer 2021 and compared to such responses from the earlier winter. Winter samples were exposed to temperatures of 15, 20, 25, 30 °C while summer samples were incubated at 15, 25, 30, 33 °C, representing the maximum range the cells might experience throughout the water column due to daytime surface heating or extreme weather events. Depending on thermal history of the cells, photosynthetic performance differed when cells were exposed to the same temperature, showing a capacity for thermal acclimation in this species. Although blooms generally do not persist throughout the summer, bloom biomass was remarkably higher in summer than during the winter. However, most of the photosynthetic parameters and N uptake rates, as well as total carbon (C) and N cell-1 were significantly lower in the summer populations, showing that the summer populations were photosynthetically and nutritionally stressed. When the summer cells were treated with urea, however, uptake rates and total C and N cell-1 were higher than with the other N substrates, especially in warmer waters, showing differential thermal responses depending on N forms.

[Impacts of F/M Ratio on Microbial Networks in Activated Sludge].

The performance of wastewater treatment plants (WWTPs) mainly relies on the microbial community in activated sludge (AS). The food to microorganisms (F/M) ratio is an important operational parameter, the recommended value of which is between 0.2 and 0.5 kg·(kg·d)-1. The F/M directly influences microbial growth and metabolism, but how the F/M ratio affects AS microbial networks and the related mechanisms remain unclear. In this study, 63 AS samples with different F/M ratios were analyzed by utilizing a random-matrix-theory based network pipeline. Firstly, all 63 samples were divided into three groups based on their F/M ratios (lower F/M group, normal F/M group, and higher F/M group). The results indicated that the lower F/M decreased microbial diversity and evenness significantly, but the higher F/M had no significant effects on the diversity of the microbial community. All three constructed networks were scale-free, small world, and modular, but network size and complexity were decreased in the lower and higher F/M groups. The network of the normal F/M ratio group was detected with the most nodes, the highest average clustering coefficient, and the shortest geodesic distance. The proportion of positive links was 76.8% when the F/M was within the normal range. On the contrary, 71.1% and 60.0% of positive links were identified when the F/M was below 0.2 and above 0.5 kg·(kg·d)-1. Moreover, 24 keystones were detected in the normal F/M network, whereas only 4 and 7 keystones were detected in the lower and higher F/M networks. Overall, our results provided clear evidence that the AS microbial community could be more stable and resilient to environmental disturbance when the F/M ratio was between 0.2 and 0.5 kg·(kg·d)-1.

Formulation of a protocol to evaluate the aerobic granulation potential (AGP) of an inoculum.

This paper proposes and develops a protocol for measuring the aerobic granulation potential of sludge, aiming to provide an affordable and simple alternative that can facilitate the development of aerobic granulation technology. In this sense, the protocol comprises a set of parameters and considerations that interact to create a controlled environment and stimulate cell population clustering. All of this is done in the context of procedural simplicity, low cost, and the speed at which results are obtained. The protocol is essentially a three-stage method: preparation of the substrate, adaptation of the inoculum, and implementation of the protocol. Simple parameters were measured to evaluate the granulation process: SVI, settling velocity, and morphological parameters. The protocol was validated according to optimal ranges and criteria previously established in the literature. For this purpose, an activated sludge inoculum from a domestic wastewater treatment plant was submitted to the protocol, obtaining an optimal response of the biomass (SVI5 =13.90 mL g-1, settling velocity= 25,79 m h-1, Diameter > 0.2 mm) in a relatively short time (7 d). The results show that this protocol can constitute a tool for evaluation and decision-making using traditional laboratory equipment and is applicable at different scales.