Phosphorus signifies an essential element in molecular biology, yet given the limited solubility of phosphates on early Earth, alternative sources like meteoritic phosphides have been proposed to ...incorporate phosphorus into biomolecules under prebiotic terrestrial conditions. Here, we report on a previously overlooked source of prebiotic phosphorus from interstellar phosphine (PH
) that produces key phosphorus oxoacids-phosphoric acid (H
PO
), phosphonic acid (H
PO
), and pyrophosphoric acid (H
P
O
)-in interstellar analog ices exposed to ionizing radiation at temperatures as low as 5 K. Since the processed material of molecular clouds eventually enters circumstellar disks and is partially incorporated into planetesimals like proto Earth, an understanding of the facile synthesis of oxoacids is essential to untangle the origin of water-soluble prebiotic phosphorus compounds and how they might have been incorporated into organisms not only on Earth, but potentially in our universe as well.
FXYD proteins are novel regulators of Na(+)-K(+)-ATPase (NKA). In fish subjected to salinity challenges, NKA activity in osmoregulatory organs (e.g., gills) is a primary driving force for the many ...ion transport systems that act in concert to maintain a stable internal environment. Although teleostean FXYD proteins have been identified and investigated, previous studies focused on only a limited group of species. The purposes of the present study were to establish the brackish medaka (Oryzias dancena) as a potential saltwater fish model for osmoregulatory studies and to investigate the diversity of teleostean FXYD expression profiles by comparing two closely related euryhaline model teleosts, brackish medaka and Japanese medaka (O. latipes), upon exposure to salinity changes. Seven members of the FXYD protein family were identified in each medaka species, and the expression of most branchial fxyd genes was salinity-dependent. Among the cloned genes, fxyd11 was expressed specifically in the gills and at a significantly higher level than the other fxyd genes. In the brackish medaka, branchial fxyd11 expression was localized to the NKA-immunoreactive cells in gill epithelia. Furthermore, the FXYD11 protein interacted with the NKA α-subunit and was expressed at a higher level in freshwater-acclimated individuals relative to fish in other salinity groups. The protein sequences and tissue distributions of the FXYD proteins were very similar between the two medaka species, but different expression profiles were observed upon salinity challenge for most branchial fxyd genes. Salinity changes produced different effects on the FXYD11 and NKA α-subunit expression patterns in the gills of the brackish medaka. To our knowledge, this report is the first to focus on FXYD expression in the gills of closely related euryhaline teleosts. Given the advantages conferred by the well-developed Japanese medaka system, we propose the brackish medaka as a saltwater fish model for osmoregulatory studies.
Chloroplasts are the sites for photosynthesis, and two Golden2-like factors act as transcriptional activators of chloroplast development in rice (Oryza sativa L.) and maize (Zea mays L.). Rice OsGLK1 ...and OsGLK2 are orthologous to maize ZmGLK1 (ZmG1) and ZmGLK2 (ZmG2), respectively. However, while rice OsGLK1 and OsGLK2 act redundantly to regulate chloroplast development in mesophyll cells, maize ZmG1 and ZmG2 are functionally specialized and expressed in different cell-specific manners. To boost rice chloroplast development and photosynthesis, we generated transgenic rice plants overexpressing ZmG1 and ZmG2, individually or simultaneously, with constitutive promoters (pZmUbi::ZmG1 and p35S::ZmG2) or maize promoters (pZmG1::ZmG1, pZmG2::ZmG2, and pZmG1::ZmG1/pZmG2::ZmG2). Both ZmG1 and ZmG2 genes were highly expressed in transgenic rice leaves. Moreover, ZmG1 and ZmG2 showed coordinated expression in pZmG1::ZmG1/pZmG2::ZmG2 plants. All Golden2-like (GLK) transgenic plants had higher chlorophyll and protein contents, Rubisco activities and photosynthetic rates per unit leaf area in flag leaves. However, the highest grain yields occurred when maize promoters were used; pZmG1::ZmG1, pZmG2::ZmG2, and pZmG1::ZmG1/pZmG2::ZmG2 transgenic plants showed increases in grain yield by 51%, 47%, and 70%, respectively. In contrast, the pZmUbi::ZmG1 plant produced smaller seeds without yield increases. Transcriptome analysis indicated that maize GLKs act as master regulators promoting the expression of both photosynthesis-related and stress-responsive regulatory genes in both rice shoot and root. Thus, by promoting these important functions under the control of their own promoters, maize GLK1 and GLK2 genes together dramatically improved rice photosynthetic performance and productivity. A similar approach can potentially improve the productivity of many other crops.
Milkfish is an important aquaculture species in Taiwan, and its high mortality during cold snaps in winter usually causes huge economic losses. To understand the effect of hypothermal stress and the ...corresponding compensatory stress response in milkfish, this study aimed to compare liver and gill protein levels between milkfish exposed to nonlethal (18°C), lethal (16°C), and control (28°C) temperatures. Using a proteomics approach based on two-dimensional electrophoresis and nano-LC-MS/MS analysis, this study identified thirty unique protein spots from milkfish livers and gills for which protein abundance was significantly different between nonlethal, lethal, and control temperature groups. Proteins identified in the liver were classified into three different categories according to their cellular function: (1) anti-oxidative stress, (2) apoptotic pathway, and (3) cytoskeleton. Similarly, proteins identified in the gill were sorted in five different functional categories: (1) cytoskeleton, (2) immune response, (3) protein quality control, (4) energy production, and (5) intracellular homeostasis. Based on functional information derived from the identified proteins, we assumed that different levels of hypothermal stress had a different effect and induced a different cellular response. Upon nonlethal hypothermal stress, the identified proteins were involved in anti-oxidative stress and anti-inflammation pathways, suggesting that milkfish had high levels of oxidative stress in the liver and exhibited inflammation response in the gill. Upon lethal hypothermal stress, however, identified proteins were associated with apoptosis in the liver and regulation of intracellular homeostasis in the gill. The present study provided evidence to illustrate different multi-physiological responses to nonlethal and lethal hypothermal stress in milkfish livers and gills.
In this study, microporous ZIF-7 crystal particles were successfully incorporated into chitosan (CS) membranes to form ZIF-7/CS mixed-matrix membranes (MMMs). The as-prepared ZIF-7/CS MMMs were used ...to separate mixtures of water/ethanol at 25°C in the pervaporation process. The different ZIF-7 loadings in CS polymer with 0.25g GA, such as 2.5, 4, 5, 6 and 7.5wt%, have been tried and ZIF-7 with 5wt% loading is the best loading condition. The separation efficiency of MMMs with 5wt% ZIF-7 incorporation showed 19 times higher than that of the pristine CS membranes because of the rigidified polymer chain of the MMMs. The separation factor and the flux of the ZIF-7/CS membranes clearly exceed the upper limit of the previously reported CS based membranes and MMMs. The present work demonstrates better pervaporation performance of the ZIF-7 incorporated CS MMMs for the separation of water and ethanol and the feasibility of using this system for pervaporation.
The mixed-matrix membranes with 5wt % ZIF-7 incorporation showed better separation efficiency in the pervaporation process than the pristine CS membranes. The present work reports the successful development of a high-performance pervaporation mixed-matrix membrane—a ZIF-7-incorporated CS membrane—for the separation of water and ethanol. Display omitted
•The ZIF-7 crystal particles exhibited good interfaces with the chitosan.•ZIF-7/CS membranes show higher separation performance.•The optimal PSI value of the ZIF-7/CS membrane is 905.5kg/m2h.
The hitherto elusive disilavinylidene (H2SiSi) molecule, which is in equilibrium with the mono‐bridged (Si(H)SiH) and di‐bridged (Si(H2)Si) isomers, was initially formed in the gas‐phase reaction of ...ground‐state atomic silicon (Si) with silane (SiH4) under single‐collision conditions in crossed molecular beam experiments. Combined with state‐of‐the‐art electronic structure and statistical calculations, the reaction was found to involve an initial formation of a van der Waals complex in the entrance channel, a submerged barrier to insertion, intersystem crossing (ISC) from the triplet to the singlet manifold, and hydrogen migrations. These studies provide a rare glimpse of silicon chemistry on the molecular level and shed light on the remarkable non‐adiabatic reaction dynamics of silicon, which are quite distinct from those of isovalent carbon systems, providing important insight that reveals an exotic silicon chemistry to form disilavinylidene.
Si/C isoelectronicity: The gas‐phase bimolecular reaction of the ground‐state silicon with silane (SiH4) under single‐collision conditions provides a rare glimpse at previously disregarded silicon chemistry on the molecular level, which further develops our understanding of the concept of isoelectronicity proposed about a century ago.
Artificial intelligence based maximum power point tracking (MPPT) techniques play an essential role in improving the efficiency of photovoltaic power conversion systems. Over the past few years, ...researchers around the world have proposed various nature-inspired metaheuristic optimization algorithms in order to extract the highest possible power from photovoltaic (PV) systems under partial shading conditions. These approaches were developed to track for the maximum power point (MPP) efficiently with fast convergence speed and high accuracy. This paper provides a systematic review on these state-of-the-art computing mechanisms with their recent advancements, modifications and adaptations in tracking for the MPP of PV systems under partial shading conditions. The technical advantages, trade-offs, and challenges of these computation mechanisms are analysed and discussed. In-depth study found that nature-inspired swarm search mechanisms are highly suitable to be implemented as MPPT schemes in PV applications. Recent developments and improvements show enhancements in multiple different aspects, especially in the accuracy and the speed of the search algorithms. Several research gaps are identified and discussed to guide future research directions.
Platinum complexes featuring pyridine bis-N-heterocyclic-imidazol-2-ylidene/-mesoionic-triazol-5-ylidene donors as pincer ligands and chloro (-Cl), acetonitrile (-NCCH3) or cyano (-CN) groups as ...auxiliary ligands are prepared as highly strained organometallic phosphors. X-ray structures of four of these complexes confirm a distorted square planar geometry, where the pincer ligand and its mesityl wingtips occur in a twisted conformation to each other. Electrochemical and photophysical characterization have been carried out and the experimental results are interpreted with the aid of density functional theory calculations. Emission responses of complexes under exposure to different vapors and mechanical shear are reported. Notably, the platinum complex featuring pyridine bis-imidazol-2-ylidene and a weakly donating acetonitrile auxiliary ligand exhibited strong aquachromic and mechanochromic emission responses, showing color changes from sky blue to green or yellow-green.
The superior photosynthetic efficiency of C
leaves over C
leaves is owing to their unique Kranz anatomy, in which the vein is surrounded by one layer of bundle sheath (BS) cells and one layer of ...mesophyll (M) cells. Kranz anatomy development starts from three contiguous ground meristem (GM) cells, but its regulators and underlying molecular mechanism are largely unknown. To identify the regulators, we obtained the transcriptomes of 11 maize embryonic leaf cell types from five stages of pre-Kranz cells starting from median GM cells and six stages of pre-M cells starting from undifferentiated cells. Principal component and clustering analyses of transcriptomic data revealed rapid pre-Kranz cell differentiation in the first two stages but slow differentiation in the last three stages, suggesting early Kranz cell fate determination. In contrast, pre-M cells exhibit a more prolonged transcriptional differentiation process. Differential gene expression and coexpression analyses identified gene coexpression modules, one of which included 3 auxin transporter and 18 transcription factor (TF) genes, including known regulators of Kranz anatomy and/or vascular development. In situ hybridization of 11 TF genes validated their expression in early Kranz development. We determined the binding motifs of 15 TFs, predicted TF target gene relationships among the 18 TF and 3 auxin transporter genes, and validated 67 predictions by electrophoresis mobility shift assay. From these data, we constructed a gene regulatory network for Kranz development. Our study sheds light on the regulation of early maize leaf development and provides candidate leaf development regulators for future study.
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