An efficient triose phosphate synthesis and distribution in wheat provides tolerance to higher field temperatures.

High temperatures in the field hinder bread wheat high-yield production, mainly because of the adverse effects of heat over photosynthesis. The Yaqui Valley, the main wheat producer region in Mexico, is a zone prone to have temperatures over 30°C. The aim of this work was to test the flag leaf photosynthetic performance in 10 bread wheat genotypes grown under high temperatures in the field. The study took place during two seasons (2019-2020 and 2020-2021). In each season, control seeds were sown in December, while heat-stressed were sown in late January to subject wheat to heat stress (HS) during the grain-filling stage. HS reduced Grain yield from 20 to 58% in the first season. HS did not reduce chlorophyll content and light-dependent reactions were unaffected in any of the tested genotypes. Rubisco, chloroplast fructose 1,6-biphosphatase (FBPase), and sucrose phosphate synthase (SPS) activities were measured spectrophotometrically. Rubisco activity did not decrease under HS in any of the genotypes. FBPase activity was reduced by HS indicating that triose phosphate flux to starch synthesis was reduced, while SPS was not affected, and thus, sucrose synthesis was maintained. HS reduced aerial biomass in the 10 chosen genotypes. Genotypes SOKWB.1, SOKWB.3, and BORLAUG100 maintained their yield under HS, pointing to a potential success in their introduction in this region for breeding heat-tolerant bread wheat.

Shrimp Glucose-6-phosphatase 2 (G6Pase 2): a second isoform of G6Pase in the Pacific white shrimp and regulation of G6Pase 1 and 2 isoforms via HIF-1 during hypoxia and reoxygenation in juveniles.

Animals suffer hypoxia when their oxygen consumption is larger than the oxygen available. Hypoxia affects the white shrimp Penaeus (Litopenaeus) vannamei, both in their natural habitat and in cultivation farms. Shrimp regulates some enzymes that participate in energy production pathways as a strategy to survive during hypoxia. Glucose-6-phosphatase (G6Pase) is key to maintain blood glucose homeostasis through gluconeogenesis and glycogenolysis. We previously reported a shrimp G6Pase gene (G6Pase1) and in this work, we report a second isoform that we named G6Pase2. The expression of the two isoforms was evaluated in oxygen limited conditions and during silencing of the transcription factor HIF-1. High G6Pase activity was detected in hepatopancreas followed by muscle and gills under good oxygen and feeding conditions. Gene expression of both isoforms was analyzed in normoxia, hypoxia and reoxygenation in hepatopancreas and gills, and in HIF-1-silenced shrimp. In fed shrimp with normal dissolved oxygen (DO) (5.0 mg L- 1 DO) the expression of G6Pase1 was detected in gills, but not in hepatopancreas or muscle, while G6Pase2 expression was undetectable in all three tissues. In hepatopancreas, G6Pase1 is induced at 3 and 48 h of hypoxia, while G6Pase2 is down-regulated in the same time points but in reoxygenation, both due to the knock-down of HIF-1. In gills, only G6Pase1 was detected, and was induced by the silencing of HIF-1 only after 3 h of reoxygenation. Therefore, the expression of the two isoforms appears to be regulated by HIF-1 at transcriptional level in response to oxygen deprivation and subsequent recovery of oxygen levels.

The pyruvate kinase of the whiteleg shrimp Litopenaeus vannamei: Gene structure and responses to short term hypoxia.

The shrimp Litopenaeus vannamei is the main farmed crustacean worldwide. This shrimp suffers environmental changes in oxygen availability that affect its energy metabolism. Pyruvate kinase (PK) catalyzes the last reaction of glycolysis and is key for the regulation of glycolysis and gluconeogenesis. There is ample knowledge about mammalian PK, but in crustaceans, the information is very scarce. In this study, we analyzed in silico the structures of the PK gene and protein. Also, the effects of hypoxia on gene expression, enzymatic activity, glucose, and lactate in hepatopancreas and muscle were analyzed. The PK gene is 15,103 bp and contains 11 exons and 10 introns, producing four mRNA variants by alternative splicing and named PK1, PK2, PK3 and PK4, that results in two proteins with longer C-terminus and two with a 12 bp insertion. The promoter contains putative binding sites for transcription factors (TF) that are typically involved in stress responses. The deduced amino acid sequences contain the classic domains, binding sites for allosteric effectors and potential reversible phosphorylation residues. Protein modeling indicates a homotetramer with highly conserved structure. The effect of hypoxia for 6 and 12 h showed tissue-specific patterns, with higher expression, enzyme activity and lactate in muscle, but higher glucose in hepatopancreas. Changes in response to hypoxia were detected at 12 h in expression with induction in muscle and reduction in hepatopancreas, while enzyme activity was maintained, and glucose and lactate decreased. These results show rapid changes in expression and metabolites, while enzyme activity was maintained to cope with short-term hypoxia.

Effect of the drug cyclophosphamide on the activity of porcine kidney betaine aldehyde dehydrogenase.

The enzyme betaine aldehyde dehydrogenase (BADH EC 1.2.1.8) catalyzes the synthesis of glycine betaine (GB), an osmolyte and osmoprotectant. Also, it participates in several metabolic pathways in humans. All BADHs known have cysteine in the active site involved in the aldehyde binding, whereas the porcine kidney enzyme (pkBADH) also has a neighborhood cysteine, both sensitive to oxidation. The antineoplastic and immuno-suppressant pre-drug cyclophosphamide (CTX), and its bioactivation products, have two highly oxidating chlorine atoms. This work aimed to analyze the effect of CTX in the activity of porcine kidney betaine aldehyde dehydrogenase. PkBADH was incubated with varying CTX concentration (0 to 2.0 mM) at 25 °C and lost 50 % of its activity with 2.0 mM CTX. The presence of the coenzyme NAD+ (0.5 mM) decreased 95% the activity in 2.0 mM CTX. The substrate betaine aldehyde (0.05 and 0.4 mM, and the products NADH (0.1-0.5 mM) and GB (1 and 10 mM) did not have an effect on the enzyme inactivation by CTX. The reducing agents, dithiothreitol and ß-mercaptoethanol, reverted the pkBADH inactivation, but reduced glutathione (GSH) was unable to restore the enzyme activity. Molecular docking showed that CTX could enter at the enzyme active site, where its chlorine atoms may interact with the catalytic and the neighboring cysteines. The results obtained show that CTX inactivates the pkBADH due to oxidation of the catalytic cysteine or because it oxidizes catalytic and neighborhood cysteine, forming a disulfide bridge with a concomitant decrease in the activity of the enzyme.

Mitochondrial manganese superoxide dismutase knock-down increases oxidative stress and caspase-3 activity in the white shrimp Litopenaeus vannamei exposed to high temperature, hypoxia, and reoxygenation.

Shrimp are increasingly exposed to warmer temperatures and lower oxygen concentrations in their habitat due to climate change. These conditions may lead to oxidative stress and apoptosis. We studied the effects of high temperature, hypoxia, reoxygenation, and the combination of these factors on lipid peroxidation, protein carbonylation, and caspase-3 activity in gills of white shrimp Litopenaeus vannamei. Silencing of mitochondrial manganese superoxide dismutase (mMnSOD) was used to determine the role of this enzyme in response to the abiotic stressors described above, to avoid oxidative damage and apoptosis. In addition, mMnSOD gene expression and mitochondrial SOD activity were evaluated to determine the efficiency of silencing this enzyme. The results showed that there was no effect of the abiotic stress conditions on the thiobarbituric acid reactive substances (TBARS), but protein carbonylation increased in all the oxidative stress treatments and caspase-3 activity decreased in hypoxia at 28 °C. On the other hand, mMnSOD-silenced shrimp experienced higher oxidative stress, since TBARS, carbonylated proteins and caspase-3 activity increased in some silenced treatments. Unexpectedly, mitochondrial SOD activity increased in some of the silenced treatments as well. Altogether, these results suggest that mMnSOD has a key role in shrimp for the prevention of oxidative damage development and induction of apoptosis in response to hypoxia, reoxygenation, high temperature, and their interactions, as conditions derived from climate change.

Spectroscopic analysis of coenzyme binding to betaine aldehyde dehydrogenase dependent on potassium.

Glycine betaine is the main osmolyte synthesized and accumulated in mammalian renal cells. Glycine betaine synthesis is catalyzed by the enzyme betaine aldehyde dehydrogenase (BADH) using NAD+ as the coenzyme. Previous studies have shown that porcine kidney betaine aldehyde dehydrogenase (pkBADH) binds NAD+ with different affinities at each active site and that the binding is K+ dependent. The objective of this work was to analyze the changes in the pkBADH secondary and tertiary structure resulting from variable concentrations of NAD+ and the role played by K+ . Intrinsic fluorescence studies were carried out at fixed-variable concentrations of K+ and titrating the enzyme with varying concentrations of NAD+ . Fluorescence analysis showed a shift of the maximum emission towards red as the concentration of K+ was increased. Changes in the exposure of tryptophan located near the NAD+ binding site were found when the enzyme was titrated with NAD+ in the presence of potassium. Fluorescence data analysis showed that the K+ presence promoted static quenching that facilitated the pkBADH-NAD+ complex formation. DC data analysis showed that binding of K+ to the enzyme caused changes in the α-helix content of 4% and 12% in the presence of 25 mM and 100 mM K+ , respectively. The presence of K+ during NAD+ binding to pkBADH increased the thermal stability of the complex. These results indicated that K+ facilitated the pkBADH-NAD+ complex formation and suggested that K+ caused small changes in secondary and tertiary structures that could influence the active site conformation.

Heterogeneity of active sites in recombinant betaine aldehyde dehydrogenase is modulated by potassium.

Betaine aldehyde dehydrogenase (BADH EC 1.2.1.8) catalyzes the irreversible oxidation of betaine aldehyde to glycine betaine using NAD+ as a coenzyme. Porcine kidney BADH (pkBADH) follows a bi-bi ordered mechanism in which NAD+ binds to the enzyme before the aldehyde. Previous studies showed that NAD+ induces complex and unusual conformational changes on pkBADH and that potassium is required to maintain its quaternary structure. The aim of this work was to analyze the structural changes in pkBADH caused by NAD+ binding and the role played by potassium in those changes. The pkBADH cDNA was cloned and overexpressed in Escherichia coli, and the protein was purified by affinity chromatography using a chitin matrix. The pkBADH/NAD+ interaction was analyzed by circular dichroism (CD) and by isothermal titration calorimetry (ITC) by titrating the enzyme with NAD+ . The cDNA has an open reading frame of 1485 bp and encodes a protein of 494 amino acids, with a predicted molecular mass of 53.9 kDa. CD data showed that the binding of NAD+ to the enzyme caused changes in its secondary structure, whereas the presence of K+ helps maintain its α-helix content. K+ increased the thermal stability of the pkBADH-NAD+ complex by 5.3°C. ITC data showed that NAD+ binding occurs with different association constants for each active site between 37.5 and 8.6 µM. All the results support previous data in which the enzyme incubation with NAD+ provoked changes in reactivity, which is an indication of slow conformational rearrangements of the active site.

Role of potassium levels in pkBADH heterogeneity of NAD+ binding site.

Betaine aldehyde dehydrogenase (BADH) catalyzes the oxidation of betaine aldehyde to glycine betaine using NAD+ as a coenzyme. Studies in porcine kidney BADH (pkBADH) suggested that the enzyme exhibits heterogeneity of active sites and undergoes potassium-induced conformational changes. This study aimed to analyze if potassium concentration plays a role in the heterogeneity of pkBADH active sites through changes in NAD+ affinity constants, in its secondary structure content and stability. The enzyme was titrated with NAD+ 1 mM at fixed-variable KCl concentration, and the interaction measured by Isothermal Titration Calorimetry (ITC) and Circular Dichroism (CD). ITC data showed that K+ increased the first active site affinity in a manner dependent on its concentration; KD values to the first site were 14.4, 13.1, and 10.4 µM, at 25, 50, and 75 mM KCl. ΔG values showed that the coenzyme binding is a spontaneous reaction without changes between active sites or depending on KCl concentration. ΔH and TΔSb values showed that NAD+ binding to the active site is an endothermic process and is carried out at the expense of changes in entropy. α-Helix content increased as KCl increased, enzyme (Tm)app values were 2.6 °C and 3.3 °C higher at 20 mM and 200 mM K+. PkBADH molecular model showed three different interaction K+ sites. Results suggested K+ can interact with pkBADH and cause changes in the secondary structure, it provokes changes in the enzyme affinity by the coenzyme, and in the thermostability.

Effect of salinity on the synthesis and concentration of glycine betaine in osmoregulatory tissues from juvenile shrimps Litopenaeus vannamei.

In marine animals, glycine betaine is one of the main osmolytes accumulated under osmotic stress conditions; nevertheless, in penaeids, shrimps little is known about the pathways involved in glycine betaine biosynthesis. In animal cells, glycine betaine is synthesized by the enzyme betaine aldehyde dehydrogenase (BADH). We herein investigated the salinity effect on the synthesis and concentration of glycine betaine on white shrimp Litopenaeus vannamei. Shrimps were subjected to 10, 20, 35, 40, 50, and 60 ppt salinity conditions for seven days. BADH activity increased in hepatopancreas and gills of shrimps subjected to salinities above 35 ppt salinity. In muscle, the BADH activity decreased at 35 ppt salinity. In hepatopancreas from shrimps subjected to 50 and 60 ppt salinities, BADH activity increased 1.1 and 1.7-fold. At 60 ppt salinity, BADH activity increased 1.5-fold respect to 35 ppt in gills. Glycine betaine concentration increased in hepatopancreas, gills, muscle, and hemolymph in shrimps subjected to salinities above 35 ppt. Glycine betaine concentration also increased at 20 ppt salinity, while at 10 ppt, not detected significant differences. The catch of glycine betaine from hemolymph by the cell likely is carried out to avoid protein denaturalization. Ammonia concentration in the aquarium's water only increased at salinities of 20 ppt and 10 ppt (1.1-fold relative to 35 ppt). Our data demonstrated that in L. vannamei, salinity regulates BADH activity and glycine betaine content in a tissue-specific manner.

Purification and partial biochemical characterization of recombinant lactate dehydrogenase 1 (LDH-1) of the white shrimp Litopenaeus vannamei.

Lactate dehydrogenase (LDH) is a key enzyme to produce energy during hypoxia by anaerobic glycolysis. In the white shrimp Litopenaeus vannamei, two protein subunits (LDH-1 and LDH-2) were previously identified, deduced from two different transcripts that come from the same LDH gene by processing via mutually exclusive alternative splicing. LDH-1 contains exon five and LDH-2 contains exon six and the two proteins differ only in 15 amino acid residues. Both subunits were independently cloned and overexpressed in E. coli as a fusion protein containing a chitin binding domain. Previously, recombinant LDH-2 was successfully purified and characterized, but LDH-1 was insoluble and aggregated forming inclusion bodies. We report the production of soluble LDH-1 by testing different pHs in the buffers used to lyse the bacterial cells before the purification step and the characterization of the purified protein to show that the cDNA indeed codes for a functional and active protein. The recombinant native protein is a homotetramer of approximately 140 kDa composed by 36 kDa subunits and has higher affinity for pyruvate than for lactate. LDH-1 has an optimum pH of 7.5 and is stable between pH 8.0 and 9.0; pH data analysis showed two pKa values of 6.1 ±â€¯0.15 and 8.8 ±â€¯0.15 suggesting a histidine and asparagine, respectively, involved in the active site. The enzyme optimal temperature was 44 °C and it was stable between 20 and 60 °C. LDH-1 was slightly activated by NaCl, KCl and MgCl2 and fully inhibited by ZnCl2.

Rheology and microstructure of gels based on wheat arabinoxylans enzymatically modified in arabinose to xylose ratio.

BACKGROUND: Arabinoxylans (AX) are polysaccharides consisting of a backbone of xyloses with arabinose substituents ester-linked to ferulic acid (FA). The arabinose to xylose ratio (A/X) in AX may vary from 0.3 to 1.1. AX form covalent gels by cross-linking of FA but physical interactions between AX chains also contribute to the network formation. The present study aimed to investigate the rheological and microstructural characteristics of gels based on AX enzymatically modified in A/X. RESULTS: Tailored AX presented A/X ranging from 0.68 to 0.51 and formed covalent gels. Dimers of FA content and elasticity (G') increased from 0.31 to 0.39 g kg-1 AX and from 106 to 164 Pa when the A/X in the polysaccharide decreased from 0.68 to 0.51. Atomic force microscopy images of AX gels showed a sponge-like microstructure at A/X = 0.68, whereas, at lower values, gels presented a more compact microstructure. Scanning electron microscopy analysis of AX gels show an arrangement of different morphology, passing from an imperfect honeycomb (A/X = 0.68) to a flake-like microstructure (A/X = 0.51). CONCLUSION: Lower A/X values favor the aggregation of AX chains resulting in an increase in di-FA content, which improves the rheological and microstructural characteristics of the gel formed. © 2017 Society of Chemical Industry.

Biotechnological potential of bacteria isolated from cattle environments of desert soils in Sonora Mexico.

The aim of this research was to study the hydrolytic potential of bacteria isolated from cattle environments of two desert soils in one of the driest and hottest zones in America. A total of 26 points were sampled, 144 strains were isolated, and 50 strains were selected for the characterization of esterase, lipase, protease, and amylase activities and for 16S rRNA identification. Strains of the Bacillus, Pseudomonas, Acinetobacter, Enterobacter, Providencia, Escherichia, and Pantoea genera were identified. Comparisons of the proteolytic activity of the secretome from 14 strains (Bacillus n = 7, Escherichia n = 2; Providencia, Pseudomonas, Enterobacter, Pantoea and Acinetobacter n = 1) were performed. Four strains of Bacillus showed the highest proteolytic activity. These strains were characterized through a comparative analysis of pH and temperature as well as the effects of salt concentration on protease activity. Maximum proteolytic activity occurred in the range of pH 7-9 and temperatures between 50 and 70 °C for B. subtilis WD01, B. tequilensis WS11, B. tequilensis WS13, and B. tequilensis WS14. At a 20% NaCl concentration, the proteolytic activity retained was 71.4%, 65%, and 79.8% for WD01, WS11, and WS13, respectively; the activity of strain WS14 increased with 45% NaCl. Protease production by B. tequilensis WS14 with wheat, fish, and bone flours as low-cost substrates showed no differences between bone and fish flours and showed a decrease in protease production with wheat flour. The proteolytic activity in flour extracts with 20% NaCl was 82%, 75.61% and 38.04% for fish, bone and wheat flours, respectively. Data obtained in this work allow us to propose that strains isolated from environments with extreme conditions have a biotechnological potential.

White shrimp Litopenaeus vannamei recombinant lactate dehydrogenase: Biochemical and kinetic characterization.

Shrimp lactate dehydrogenase (LDH) is induced in response to environmental hypoxia. Two protein subunits deduced from different transcripts of the LDH gene from the shrimp Litopenaeus vannamei (LDHvan-1 and LDHvan-2) were identified. These subunits are expressed by alternative splicing. Since both subunits are expressed in most tissues, the purification of the enzyme from the shrimp will likely produce hetero LDH containing both subunits. Therefore, the aim of this study was to overexpress, purify and characterize only one subunit as a recombinant protein, the LDHvan-2. For this, the cDNA from muscle was cloned and overexpressed in E. coli as a fusion protein containing an intein and a chitin binding protein domain (CBD). The recombinant protein was purified by chitin affinity chromatography column that retained the CBD and released solely the full and active LDH. The active protein appears to be a tetramer with molecular mass of approximately 140 kDa and can use pyruvate or lactate as substrates, but has higher specific activity with pyruvate. The enzyme is stable between pH 7.0 to 8.5, and between 20 and 50 °C with an optimal temperature of 50 °C. Two pKa of 9.3 and 6.6, and activation energy of 44.8 kJ/mol°K were found. The kinetic constants Km for NADH was 23.4 ± 1.8 µM, and for pyruvate was 203 ± 25 µM, while Vmax was 7.45 µmol/min/mg protein. The shrimp LDH that is mainly expressed in shrimp muscle preferentially converts pyruvate to lactate and is an important enzyme for the response to hypoxia.

Role of HIF-1 on phosphofructokinase and fructose 1, 6-bisphosphatase expression during hypoxia in the white shrimp Litopenaeus vannamei.

HIF-1 is a transcription factor that controls a widespread range of genes in metazoan organisms in response to hypoxia and is composed of α and ß subunits. In shrimp, phosphofructokinase (PFK) and fructose bisphosphatase (FBP) are up-regulated in hypoxia. We hypothesized that HIF-1 is involved in the regulation of PFK and FBP genes in shrimp hepatopancreas under hypoxia. Long double stranded RNA (dsRNA) intramuscular injection was utilized to silence simultaneously both HIF-1 subunits, and then, we measured the relative expression of PFK and FBP, as well as their corresponding enzymatic activities in hypoxic shrimp hepatopancreas. The results indicated that HIF-1 participates in the up-regulation of PFK transcripts under short-term hypoxia since the induction caused by hypoxia (~1.6 and ~4.2-fold after 3 and 48h, respectively) is significantly reduced in the dsRNA animals treated. Moreover, PFK activity was significantly ~2.8-fold augmented after 3h in hypoxia alongside to an ~1.9-fold increment in lactate. However, when animals were dsRNA treated, both were significantly reduced. On the other hand, FBP transcripts were ~5.3-fold up-regulated in long-term hypoxic conditions (48h). HIF-1 is involved in this process since FBP transcripts were not induced by hypoxia when HIF-1 was silenced. Conversely, the FBP activity was not affected by hypoxia, which suggests its possible regulation at post-translational level. Taken together, these results position HIF-1 as a prime transcription factor in coordinating glucose metabolism through the PFK and FBP genes among others, in shrimp under low oxygen environments.

Responses and modulation of the white shrimp Litopenaeus vannamei glutathione peroxidases 2 and 4 during hypoxia, reoxygenation and GPx4 knock-down.

Glutathione peroxidases (GPxs) are important antioxidant enzymes that act at distinct levels of the antioxidant defense. In vertebrates, there are several glutathione peroxidase (GPx) isoforms with different cellular and tissue distribution, but little is known about their interrelationships. The shrimp Litopenaeus vannamei is the main crustacean cultivated worldwide. It is affected by environmental stressors, including hypoxia and reoxygenation that cause reactive oxygen species accumulation. Thus, the antioxidant response modulation is key for shrimp resilience. Recently, several GPx isoforms genes were identified in the L. vannamei genome sequence, but their functions are just beginning to be studied. As in vertebrates, shrimp GPx isoforms can present differences in their antioxidant responses. Also, there could be interrelationships among the isoforms that may influence their responses. We evaluated shrimp GPx2 and GPx4 expressions during hypoxia, reoxygenation, and GPx4 knock-down using RNAi for silencing, as well as the enzymatic activity of total GPx and GPx4. Also, glutathione content in hepatopancreas was evaluated. GPx2 and GPx4 presented similar expression patterns during hypoxia and reoxygenation. Their expressions decreased during hypoxia and were reestablished in reoxygenation at 6 h in non-silenced shrimp. GPx2 expression was down-regulated by GPx4 knock-down, suggesting that GPx4 affects GPx2 expression. Total GPx activity changed in hypoxia and reoxygenation at 6 h but not at 12 h, while GPx4 activity was not affected by any stressor. The GSH/GSSG ratio in hepatopancreas indicated that at early hours, the redox status remains well-modulated but at 12 h it is impaired by hypoxia and reoxygenation.

BADH-NAD+-K+ Complex Interaction Studies Reveal a New Possible Mechanism between Potassium and Glutamic 254 at the Coenzyme Binding Site.

Betaine aldehyde dehydrogenase (BADH EC 1.2.1.8) catalyzes the irreversible oxidation of betaine aldehyde to glycine betaine using NAD+ as a coenzyme. Incubation of porcine kidney BADH (pkBADH) with NAD+ decreases the catalytic cysteine (C288) reactivity. Potassium ion increases the pkBADH affinity by the coenzyme. This work aimed to analyze pkBADH and NAD+ interaction in the presence and absence of K+ using 1H NMR to identify the amino acids that interact with NAD+ and/or K+ to understand the regulation process of pkBADH-NAD+ complex formation mediated by the K+ ion and their impact on the substrate binding and catalysis. Nuclear magnetic resonance spectra of pkBADH were obtained in the presence and absence of NAD+ and K+. The results show a chemical shift of the signals corresponding to the catalytic glutamic that participates in the transfer of H+ in the reaction of the pkBADH-NAD+-K+ complex formation. Furthermore, there is a widening of the signal that belongs to the catalytic cysteine indicating higher rigidity or less grade of rotation of the structure, which is consistent with the possible conformations of C288 in the catalytic process; in addition, there is evidence of changes in the chemical environment that surrounds NAD+.

The Effects of Brief Heat During Early Booting on Reproductive, Developmental, and Chlorophyll Physiological Performance in Common Wheat (Triticum aestivum L.).

Rising temperatures due to climate change threaten agricultural crop productivity. As a cool-season crop, wheat is heat-sensitive, but often exposed to high temperatures during the cultivation period. In the current study, a bread wheat panel of spring wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes, was exposed to a 5-day mild (34°C/28°C, day/night) or extreme (37°C/27°C) heat stress during the sensitive pollen developmental stage. Worsening effects on anther morphology were observed, as heat stress increased from mild to extreme. Even under mild heat, a significant decrease in pollen viability and number of grains per spike from primary spike was observed compared with the control (21°C/15°C), with Sunstar and two CIMMYT breeding lines performing well. A heat-specific positive correlation between the two traits indicates the important role of pollen fertility for grain setting. Interestingly, both mild and extreme heat induced development of new tillers after the heat stress, providing an alternative sink for accumulated photosynthates and significantly contributing to the final yield. Measurements of flag leaf maximum potential quantum efficiency of photosystem II (Fv/Fm) showed an initial inhibition after the heat treatment, followed by a full recovery within a few days. Despite this, model fitting using chlorophyll soil plant analysis development (SPAD) measurements showed an earlier onset or faster senescence rate under heat stress. The data presented here provide interesting entry points for further research into pollen fertility, tillering dynamics, and leaf senescence under heat. The identified heat-tolerant wheat genotypes can be used to dissect the underlying mechanisms and breed climate-resilient wheat.

The glycine betaine role in neurodegenerative, cardiovascular, hepatic, and renal diseases: Insights into disease and dysfunction networks.

Glycine betaine (N, N, N-trimethyl amine) is an osmolyte accumulated in cells that is key for cell volume and turgor regulation, is the principal methyl donor in the methionine cycle and is a DNA and proteins stabilizer. In humans, glycine betaine is synthesized from choline and can be obtained from some foods. Glycine betaine (GB) roles are illustrated in chemical, metabolic, agriculture, and clinical medical studies due to its chemical and physiological properties. Several studies have extensively described GB role and accumulation related to specific pathologies, focusing mainly on analyzing its positive and negative role in these pathologies. However, it is necessary to explain the relationship between glycine betaine and different pathologies concerning its role as an antioxidant, ability to methylate DNA, interact with transcription factors and cell receptors, and participate in the control of homocysteine concentration in liver, kidney and brain. This review summarizes the most important findings and integrates GB role in neurodegenerative, cardiovascular, hepatic, and renal diseases. Furthermore, we discuss GB impact on other dysfunctions as inflammation, oxidative stress, and glucose metabolism, to understand their cross-talks and provide reliable data to establish a base for further investigations.

Expression and silencing of Selenoprotein M (SelM) from the white shrimp Litopenaeus vannamei: effect on peroxidase activity and hydrogen peroxide concentration in gills and hepatopancreas.

Selenoprotein M (SelM), is a selenocysteine containing protein with redox activity involved in the antioxidant response. In the white shrimp Litopenaeus vannamei, SelM expression in gills is induced transiently during viral infection by the White Spot Syndrome Virus (WSSV). We report that SelM expression was detected in healthy shrimp L. vannamei in gills, muscle, hepatopancreas and pleopods, with more abundance in the hepatopancreas and gills. SelM transcripts were silenced by intramuscular injection with double-stranded RNAs (dsRNAs). In gills and hepatopancreas, all shrimp injected with long dsRNAs had lower SelM transcripts levels compared with controls. Peroxidase activity and hydrogen peroxide concentration were measured to detect effects on antioxidants. Peroxidase activity decreased upon silencing of SelM in gills, but no significant effect was detected in hepatopancreas. In contrast, total cell hydrogen peroxide concentration did not change in gills and hepatopancreas of silenced shrimp. Non-heme peroxidases are new players in the oxidative stress system that need to be addressed in detail, as well as selenium as a critical micronutrient for the antioxidant and innate immune systems in crustaceans.

Differential Activation of Ferulic Acid Catabolic Pathways of Amycolatopsis sp. ATCC 39116 in Submerged and Surface Cultures.

Amycolatopsis sp. ATCC 39116 catabolizes ferulic acid by the non-oxidative deacetylation and ß-oxidation pathways to produce vanillin and vanillic acid, respectively. In submerged culture, vanillin productivity decreased more than 8-fold, when ferulic, p-coumaric, and caffeic acids were employed in pre-cultures of the microorganism in order to activate the ferulic acid catabolic pathways, resulting in a carbon redistribution since vanillic acid and guaiacol productivities increased more than 5-fold compared with control. In contrast, in surface culture, the effects of ferulic and sinapic acids in pre-cultures were totally opposite to those of the submerged culture, directing the carbon distribution into vanillin formation. In surface culture, more than 30% of ferulic acid can be used as carbon source for other metabolic processes, such as ATP regeneration. In this way, the intracellular ATP concentration remained constant during the biotransformation process by surface culture (100 µg ATP/mg protein), demonstrating a high energetic state, which can maintain active the non-oxidative deacetylation pathway. In contrast, in submerged culture, it decreased 3.15-fold at the end of the biotransformation compared with the initial content, showing a low energetic state, while the NAD+/NADH ratio (23.15) increased 1.81-fold. It seems that in submerged culture, low energetic and high oxidative states are the physiological conditions that can redirect the ferulic catabolism into ß-oxidative pathway and/or vanillin oxidation to produce vanillic acid.