Editorial: Structure and function of chloroplasts, Volume III

Chloroplasts are endosymbiotic organelles derived from cyanobacteria. They have a double envelope membrane, including the outer envelope and the inner envelope. A complex membrane system, thylakoids, exists inside the chloroplast. It is the site of the light-dependent reactions of photosynthesis. The stroma is the main site of the carbon fixation reactions. Although photosynthesis is a very complicated process with many proteins involved, there are many other important processes that occur in chloroplasts, including the regulation of photosynthesis, the biogenesis and maintenance of the structures, carbohydrate, lipid, tetrapyrrole, amino acid, and isoprenoid metabolism, production of some phytohormones, production of specialized metabolites, regulation of redox, and interactions with other parts of the cell (Sabater, 2018). During evolution, most of the cyanobacterial genes were lost and many of them were transferred into the nuclear genome. A majority of chloroplast proteins are nuclear-encoded and possess an N-terminal transit peptide which helps the protein to be targeted into chloroplasts. Chloroplasts have their own highly reduced genome which works coordinately with the nuclear genome for the biogenesis and function of chloroplasts (Liebers et al., 2022). This Research Topic presents studies covering different aspects of chloroplast function, including photosynthesis, biogenesis, structure, and maintenance. These works push the frontiers of chloroplast research further in the field of plant biology

Dynamic System Representation of Basic and Non-Linear in Parameters Oscillatory Motion Gestures

We present a system for generation and recognition of oscillatory gestures. Inspired by gestures used in two representative human-to-human control areas, we consider a set of oscillatory (circular) motions and refine from them a 24 gestures lexicon. Each gesture is modeled as a dynamic system with added geometric constraints to allow for real time gesture recognition using a small amount of processing time and memory. The gestures are used to control a pan-tilt camera neck. The gesture lexicon is then enhanced to include non-linear in parameter ( come here ) gesture representations. An enhancement is suggested which would enable the system to be trained to recognized previously unidentified yet consistent human generated oscillatory motion gestures

Functional Diversification of Thylakoidal Processing Peptidases in \u3ci\u3eArabidopsis thaliana\u3c/i\u3e

Thylakoidal processing peptidase (TPP) is responsible for removing amino-terminal thylakoid-transfer signals from several proteins in the thylakoid lumen. Three TPP isoforms are encoded by the nuclear genome of Arabidopsis thaliana. Previous studies showed that one of them termed plastidic type I signal peptidase 1 (Plsp1) was necessary for processing three thylakoidal proteins and one protein in the chloroplast envelope in vivo. The lack of Plsp1 resulted in seedling lethality, apparently due to disruption of proper thylakoid development. The physiological roles of the other two TPP homologs remain unknown. Here we show that the three A. thaliana TPP isoforms evolved to acquire diverse functions. Phylogenetic analysis revealed that TPP may have originated before the endosymbiotic event, and that there are two groups of TPP in seed plants: one includes Plsp1 and another comprises the other two A. thaliana TPP homologs, which are named as Plsp2A and Plsp2B in this study. The duplication leading to the two groups predates the gymnosperm-angiosperm divergence, and the separation of Plsp2A and Plsp2B occurred after the Malvaceae-Brassicaceae diversification. Quantitative reverse transcription-PCR assay revealed that the two PLSP2 genes were co-expressed in both photosynthetic tissues and roots, whereas the PLSP1 transcript accumulated predominantly in photosynthetic tissues. Both PLSP2 genes were expressed in the aerial parts of the plsp1-null mutant at levels comparable to those in wild-type plants. The seedling-lethal phenotype of the plsp1-null mutant could be rescued by a constitutive expression of Plsp1 cDNA but not by that of Plsp2A or Plsp2B. These results indicate that Plsp1 and Plsp2 evolved to function differently, and that neither of the Plsp2 isoforms is necessary for proper thylakoid development in photosynthetic tissues

Uso de leitos cultivados no tratamento de efluentes da aquicultura.

In the last fifty years, worldwide aquaculture has increased about 8.8% /year. In Brazil, the tilapia culture, the flagship aquaculture production, represents 39% of the total cultivated fish. The increasing demand for aquatic protein, the demographic increasement and the decline of natural stocks have contributed to the promotion of aquaculture around the world. Nevertheless, concerns about the negative environmental impacts caused by this activity are also increasing. Some of these impacts are: destruction of mangroves, significant inputs of nitrogen, phosphorus and organic matter downstream nurseries, invasion of exotic species in natural aquatic ecosystems. Natural treatment systems such as constructed wetlands are costeffective, do not depend on energy, and the efficiency of removal of the main physico-chemical parameters of water quality are at 70 to 90% on average. By bacteriological metabolism and mechanical filtration, the organic matter is used as food and nutrient for aquatic plants. This study aims to assess the efficiency of constructed wetlands for treatment of effluents from tilapia culture, using a closed cycle of water. At Embrapa Environment (Jaguariúna, SP), a system composed by 54 plastic boxes was constructed to test three kinds of substrates: pebbles, expanded clay and a mixture of both. The plant Vetiver was used as another part of the treatment system. We expect to verify a great reduction in important parameters such as total nitrogen, total phosphorus, biochemical oxygen demand, total suspended solids and others. This system could be very useful at smallholder aquaculture worried with best management practices

Functional Diversification of Thylakoidal Processing Peptidases in \u3ci\u3eArabidopsis thaliana\u3c/i\u3e

Thylakoidal processing peptidase (TPP) is responsible for removing amino-terminal thylakoid-transfer signals from several proteins in the thylakoid lumen. Three TPP isoforms are encoded by the nuclear genome of Arabidopsis thaliana. Previous studies showed that one of them termed plastidic type I signal peptidase 1 (Plsp1) was necessary for processing three thylakoidal proteins and one protein in the chloroplast envelope in vivo. The lack of Plsp1 resulted in seedling lethality, apparently due to disruption of proper thylakoid development. The physiological roles of the other two TPP homologs remain unknown. Here we show that the three A. thaliana TPP isoforms evolved to acquire diverse functions. Phylogenetic analysis revealed that TPP may have originated before the endosymbiotic event, and that there are two groups of TPP in seed plants: one includes Plsp1 and another comprises the other two A. thaliana TPP homologs, which are named as Plsp2A and Plsp2B in this study. The duplication leading to the two groups predates the gymnosperm-angiosperm divergence, and the separation of Plsp2A and Plsp2B occurred after the Malvaceae-Brassicaceae diversification. Quantitative reverse transcription-PCR assay revealed that the two PLSP2 genes were co-expressed in both photosynthetic tissues and roots, whereas the PLSP1 transcript accumulated predominantly in photosynthetic tissues. Both PLSP2 genes were expressed in the aerial parts of the plsp1-null mutant at levels comparable to those in wild-type plants. The seedling-lethal phenotype of the plsp1-null mutant could be rescued by a constitutive expression of Plsp1 cDNA but not by that of Plsp2A or Plsp2B. These results indicate that Plsp1 and Plsp2 evolved to function differently, and that neither of the Plsp2 isoforms is necessary for proper thylakoid development in photosynthetic tissues

Validação de método analítico para quantificação de interferentes endócrinos em águas residuárias após tratamento secundário.

Interferentes endócrinos são substâncias que estão cada vez mais presentes no meio ambiente, especialmente nos corpos hídricos, que podem causar câncer em seres humanos e animais, mutagenicidade nos órgãos reprodutores das espécies animais presentes na biota aquática, esterilidade em homens, entre outros efeitos adversos à saúde. Constructed wetlands são métodos alternativos de tratamento de água e efluentes, que se baseiam na retirada de poluentes pelas macrófitas aquáticas e pelo biofilme formado nas raízes das plantas fixadas ao meio suporte, simulando assim os sistemas naturais de tratamento. Eles têm como vantagem o baixo custo de implantação e manutenção, economia de energia elétrica durante seu funcionamento, além de serem eficientes na remoção de poluentes. Constructed wetlands foram citados como um eficiente método de remoção de pesticidas levemente hidrofóbicos. Neste contexto, devido ao fato de estrogênios serem substâncias levemente hidrofóbicas, o presente trabalho visou desenvolver e validar uma metodologia de análise cromatográfica para determinação quantitativa dos hormônios etinilestradiol (EE2) e levonorgestrel (LEV), e do composto químico bisfenol A (BPA) em águas residuárias após tratamento secundário, com o intuito de analisar esses compostos no afluente e efluente de uma wetland construída em escala laboratorial

Using the no-signaling condition for constraining the nonidealness of a Stern-Gerlach setup

On the basis of a variant of the EPR-Bohm example, we show that the no-signaling condition can be employed as a useful tool for deriving a constraint on a suitably defined measure of the `nonidealness' of a Stern-Gerlach(SG) setup. In this demonstration, a key ingredient is provided by the characteristics of the exact solution of the time-dependent Schroedinger equation as applied to a most general SG setup

Unraveling the role of protein dynamics in dihydrofolate reductase catalysis

Protein dynamics have controversially been proposed to be at the heart of enzyme catalysis, but identification and analysis of dynamical effects in enzyme-catalyzed reactions have proved very challenging. Here, we tackle this question by comparing an enzyme with its heavy (15N, 13C, 2H substituted) counterpart, providing a subtle probe of dynamics. The crucial hydride transfer step of the reaction (the chemical step) occurs more slowly in the heavy enzyme. A combination of experimental results, quantum mechanics/molecular mechanics simulations, and theoretical analyses identify the origins of the observed differences in reactivity. The generally slightly slower reaction in the heavy enzyme reflects differences in environmental coupling to the hydride transfer step. Importantly, the barrier and contribution of quantum tunneling are not affected, indicating no significant role for “promoting motions” in driving tunneling or modulating the barrier. The chemical step is slower in the heavy enzyme because protein motions coupled to the reaction coordinate are slower. The fact that the heavy enzyme is only slightly less active than its light counterpart shows that protein dynamics have a small, but measurable, effect on the chemical reaction rate

Catecholaminergic polymorphic ventricular tachycardia patients with multiple genetic variants in the PACES CPVT Registry.

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is often a life-threatening arrhythmia disorder with variable penetrance and expressivity. Little is known about the incidence or outcomes of CPVT patients with ≥2 variants. METHODS: The phenotypes, genotypes and outcomes of patients in the Pediatric and Congenital Electrophysiology Society CPVT Registry with ≥2 variants in genes linked to CPVT were ascertained. The American College of Medical Genetics & Genomics (ACMG) criteria and structural mapping were used to predict the pathogenicity of variants (3D model of pig RyR2 in open-state). RESULTS: Among 237 CPVT subjects, 193 (81%) had genetic testing. Fifteen patients (8%) with a median age of 9 years (IQR 5-12) had ≥2 variants. Sudden cardiac arrest occurred in 11 children (73%), although none died during a median follow-up of 4.3 years (IQR 2.5-6.1). Thirteen patients (80%) had at least two RYR2 variants, while the remaining two patients had RYR2 variants plus variants in other CPVT-linked genes. Among all variants identified, re-classification of the commercial laboratory interpretation using ACMG criteria led to the upgrade from variant of unknown significance (VUS) to pathogenic/likely pathogenic (P/LP) for 5 variants, and downgrade from P/LP to VUS for 6 variants. For RYR2 variants, 3D mapping using the RyR2 model suggested that 2 VUS by ACMG criteria were P/LP, while 2 variants were downgraded to likely benign. CONCLUSIONS: This severely affected cohort demonstrates that a minority of CPVT cases are related to ≥2 variants, which may have implications on family-based genetic counselling. While multi-variant CPVT patients were at high-risk for sudden cardiac arrest, there are insufficient data to conclude that this genetic phenomenon has prognostic implications at present. Further research is needed to determine the significance and generalizability of this observation. This study also shows that a rigorous approach to variant re-classification using the ACMG criteria and 3D mapping is important in reaching an accurate diagnosis, especially in the multi-variant population