Morphological and molecular characterization of L-methioninase producing Aspergillus species

Six species of L-methioninase producing Aspergillus species, isolated from Egyptian soil, were selected for comprehensive morphotypic and molecular characterization. Based on morphological and physiological features, these isolates were identified as Aspergillus flavipes, Aspergillus carneus, Aspergillus flavus, Aspergillus tamari, Aspergillus oryzae, and Aspergillus parasiticus. Regarding to the maximum enzyme productivity by A. flavipes, it was selected as authentic strain for ribosomal ribonucleic acid (rRNA) primer design. Using primer combinations for 18S rRNA and internal transcribed spacers (ITS)1 amplification, these isolates gave the same polymerase chain reaction (PCR) amplicon size, revealing the relative molecular identity. Moreover, using ITS2 primers, among the six isolates, Aspergillus flavipes EK and A. carneus displayed PCR products on agarose gel, approving the actual morphological and biochemical similarities of these two isolates, A. flavipes group. By sequencing of ITS1-5.8S-ITS2 region, blasting and alignment from the data base, A. flavipes EK showed a typical identity to gene bank deposited A. flavipes isolates. The rRNA sequence of A. flavipes EK was deposited to genbank under accession number JF831014.Key words: Aspergillus, morphological descriptions, 18 S rRNA, internal transcribed spacers (ITS) regions

Two alanine aminotranferases link mitochondrial glycolate oxidation to the major photorespiratory pathway in Arabidopsis and rice

The major photorespiratory pathway in higher plants is distributed over chloroplasts, mitochondria, and peroxisomes. In this pathway, glycolate oxidation takes place in peroxisomes. It was previously suggested that a mitochondrial glycolate dehydrogenase (GlcDH) that was conserved from green algae lacking leaf-type peroxisomes contributes to photorespiration in Arabidopsis thaliana. Here, the identification of two Arabidopsis mitochondrial alanine:glyoxylate aminotransferases (ALAATs) that link glycolate oxidation to glycine formation are described. By this reaction, the mitochondrial side pathway produces glycine from glyoxylate that can be used in the glycine decarboxylase (GCD) reaction of the major pathway. RNA interference (RNAi) suppression of mitochondrial ALAAT did not result in major changes in metabolite pools under standard conditions or enhanced photorespiratroy flux, respectively. However, RNAi lines showed reduced photorespiratory CO2 release and a lower CO2 compensation point. Mitochondria isolated from RNAi lines are incapable of converting glycolate to CO2, whereas simultaneous overexpression of GlcDH and ALAATs in transiently transformed tobacco leaves enhances glycolate conversion. Furthermore, analyses of rice mitochondria suggest that the side pathway for glycolate oxidation and glycine formation is conserved in monocotyledoneous plants. It is concluded that the photorespiratory pathway from green algae has been functionally conserved in higher plants

Определение эффективности способов борьбы с асфальтеносмолопарафиновыми отложениями при эксплуатации нефтяных месторождений

В качестве объекта исследования – рассматривается нефтяные месторождения, а именно Талаканского месторождения, а предметом является технологии предупреждение асфальтеносмолопарафиновых отложений (АСПО) на нефтепромысловых оборудованиях. Цель работы – определение наиболее эффективного метода борьбы с асфальтеносмолопарафиновыми отложениями, и применение технологий удаления отложений на различных нефтяных месторождениях. В процессе исследования были раскрыты причины образования парафиновых отложений и эффективность применения некоторых методов борьбы с АСПО на месторождениях. Область применения: месторождения нефти и газа, имеющие осложнения в виде асфальтосмолопарафиновых отложений.The object of the study is the oil fields, namely the Talakan field, and the subject is the technologies for the prevention of asphaltene-tar-paraffin deposits (ASPO) on oilfield equipment. The purpose of the work is to determine the most effective method of controlling asphaltene-tar-paraffin deposits, and to apply technologies for removing deposits in various oil fields. In the course of the study, the reasons for the formation of paraffin deposits and the effectiveness of the use of some methods of combating ASPO in the fields were revealed. Field of application: oil and gas fields with complications in the form of asphalt-resin-paraffin deposits

Simultaneous stimulation of sedoheptulose 1,7‐bisphosphatase, fructose 1,6‐bisphophate aldolase and the photorespiratory glycine decarboxylase‐H protein increases CO2 assimilation, vegetative biomass and seed yield in Arabidopsis

In this paper we have altered the levels of three different enzymes involved in the Calvin Benson cycle and photorespiratory pathway. We have generated transgenic Arabidopsis plants with altered combinations of sedoheptulose 1,7-bisphosphatase (SBPase), fructose 1,6-bisphophate aldolase (FBPA) and the glycine decarboxylase H-protein (GDC-H) gene identified as targets to improve photosynthesis based on previous studies. Here, we show that increasing the levels of the three corresponding proteins, either independently or in combination, significantly increases the quantum efficiency of PSII. Furthermore, photosynthetic measurements demonstrated an increase in the maximum efficiency of CO2 fixation in lines over-expressing SBPase and FBPA. Moreover, the co-expression of GDC-H with SBPase and FBPA resulted in a cumulative positive impact on leaf area and biomass. Finally, further analysis of transgenic lines revealed a cumulative increase of seed yield in SFH lines grown in high light. These results demonstrate the potential of multigene-stacking for improving the productivity of food and energy crops

Past evolutionary tradeoffs represent opportunities for crop genetic improvement and increased human lifespan

The repeated evolution of complex adaptations – crop mimicry by weeds, for example, or CO2-concentrating C4 photosynthesis – shows the power of natural selection to solve difficult problems that limited fitness in past environments. The sophistication of natural selection's innovations contrasts with the relatively simple changes (e.g., increasing the expression of existing genes) readily achievable by today's biotechnology. Mutants with greater expression of these genes arose repeatedly over the course of evolution, so their present rarity indicates rejection by natural selection. Similarly, medical interventions that simply up- or down-regulate existing physiological mechanisms presumably recreate phenotypes also rejected by past natural selection. Some tradeoffs that constrained past natural selection still apply, such as those resulting from conservation of matter. But tradeoffs between present human goals and individual fitness in past environments may represent fairly easy opportunities to achieve our goals by reversing some effects of past selection. This point is illustrated with three examples, based on tradeoffs between (i) individual-plant fitness versus whole-crop performance, (ii) the fitness of symbionts (rhizobia) versus that of their legume hosts, and (iii) human fertility versus longevity in the context of environmental cues, such as consumption of ‘famine foods’, that predict trends in population size

RBCS1A and RBCS3B, two major members within the Arabidopsis RBCS multigene family, function to yield sufficient Rubisco content for leaf photosynthetic capacity

Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit (RBCS) is encoded by a nuclear RBCS multigene family in many plant species. The contribution of the RBCS multigenes to accumulation of Rubisco holoenzyme and photosynthetic characteristics remains unclear. T-DNA insertion mutants of RBCS1A (rbcs1a-1) and RBCS3B (rbcs3b-1) were isolated among the four Arabidopsis RBCS genes, and a double mutant (rbcs1a3b-1) was generated. RBCS1A mRNA was not detected in rbcs1a-1 and rbcs1a3b-1, while the RBCS3B mRNA level was suppressed to ∼20% of the wild-type level in rbcs3b-1 and rbcs1a3b-1 leaves. As a result, total RBCS mRNA levels declined to 52, 79, and 23% of the wild-type level in rbcs1a-1, rbcs3b-1, and rbcs1a3b-1, respectively. Rubisco contents showed declines similar to total RBCS mRNA levels, and the ratio of Rubisco-nitrogen to total nitrogen was 62, 78, and 40% of the wild-type level in rbcs1a-1, rbcs3b-1, and rbcs1a3b-1, respectively. The effects of RBCS1A and RBCS3B mutations in rbcs1a3b-1 were clearly additive. The rates of CO2 assimilation at ambient CO2 of 40 Pa were reduced with decreased Rubisco contents in the respective mutant leaves. Although the RBCS composition in the Rubisco holoenzyme changed, the CO2 assimilation rates per unit of Rubisco content were the same irrespective of the genotype. These results clearly indicate that RBCS1A and RBCS3B contribute to accumulation of Rubisco in Arabidopsis leaves and that these genes work additively to yield sufficient Rubisco for photosynthetic capacity. It is also suggested that the RBCS composition in the Rubisco holoenzyme does not affect photosynthesis under the present ambient [CO2] conditions

Metabolite profiling at the cellular and subcellular level reveals metabolites associated with salinity tolerance in sugar beet

Hossain MS, Persicke M, ElSayed AI, Kalinowski J, Dietz K-J. Metabolite profiling at the cellular and subcellular level reveals metabolites associated with salinity tolerance in sugar beet. Journal of Experimental Botany. 2017;68(21-22):5961-5976.Sugar beet is among the most salt-tolerant crops. This study aimed to investigate the metabolic adaptation of sugar beet to salt stress at the cellular and subcellular levels. Seedlings were grown hydroponically and subjected to stepwise increases in salt stress up to 300 mM NaCl. Highly enriched fractions of chloroplasts were obtained by nonaqueous fractionation using organic solvents. Total leaf metabolites and metabolites in chloroplasts were profiled at 3 h and 14 d after reaching the maximum salinity stress of 300 mM NaCl. Metabolite profiling by gas chromatography- mass spectrometry (GC-MS) resulted in the identification of a total of 83 metabolites in leaves and chloroplasts under control and stress conditions. There was a lower abundance of Calvin cycle metabolites under salinity whereas there was a higher abundance of oxidative pentose phosphate cycle metabolites such as 6-phosphogluconate. Accumulation of ribose-5-phosphate and ribulose-5-phosphate coincided with limitation of carbon fixation by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Increases in glycolate and serine levels indicated that photorespiratory metabolism was stimulated in salt-stressed sugar beet. Compatible solutes such as proline, mannitol, and putrescine accumulated mostly outside the chloroplasts. Within the chloroplast, putrescine had the highest relative level and probably assisted in the acclimation of sugar beet to high salinity stress. The results provide new information on the contribution of chloroplasts and the extra-chloroplast space to salinity tolerance via metabolic adjustment in sugar beet

Metabolic Adaptation in Transplastomic Plants Massively Accumulating Recombinant Proteins

BACKGROUND: Recombinant chloroplasts are endowed with an astonishing capacity to accumulate foreign proteins. However, knowledge about the impact on resident proteins of such high levels of recombinant protein accumulation is lacking. METHODOLOGY/PRINCIPAL FINDINGS: Here we used proteomics to characterize tobacco (Nicotiana tabacum) plastid transformants massively accumulating a p-hydroxyphenyl pyruvate dioxygenase (HPPD) or a green fluorescent protein (GFP). While under the conditions used no obvious modifications in plant phenotype could be observed, these proteins accumulated to even higher levels than ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), the most abundant protein on the planet. This accumulation occurred at the expense of a limited number of leaf proteins including Rubisco. In particular, enzymes involved in CO(2) metabolism such as nuclear-encoded plastidial Calvin cycle enzymes and mitochondrial glycine decarboxylase were found to adjust their accumulation level to these novel physiological conditions. CONCLUSIONS/SIGNIFICANCE: The results document how protein synthetic capacity is limited in plant cells. They may provide new avenues to evaluate possible bottlenecks in recombinant protein technology and to maintain plant fitness in future studies aiming at producing recombinant proteins of interest through chloroplast transformation

Update on chloroplast research

Chloroplasts, the green differentiation form of plastids, are the sites of photosynthesis and other important plant functions. Genetic and genomic technologies have greatly boosted the rate of discovery and functional characterization of chloroplast proteins during the past decade. Indeed, data obtained using high-throughput methodologies, in particular proteomics and transcriptomics, are now routinely used to assign functions to chloroplast proteins. Our knowledge of many chloroplast processes, notably photosynthesis and photorespiration, has reached such an advanced state that biotechnological approaches to crop improvement now seem feasible. Meanwhile, efforts to identify the entire complement of chloroplast proteins and their interactions are progressing rapidly, making the organelle a prime target for systems biology research in plants