Microstructure investigation of plant architecture with X-ray microscopy.

In recent years, the plant morphology has been well studied by multiple approaches at cellular and subcellular levels. Two-dimensional (2D) microscopy techniques offer imaging of plant structures on a wide range of magnifications for researchers. However, subcellular imaging is still challenging in plant tissues like roots and seeds. Here we use a three-dimensional (3D) imaging technology based on the X-ray microscope (XRM) and analyze several plant tissues from different plant species. The XRM provides new insights into plant structures using non-destructive imaging at high-resolution and high contrast. We also utilized a workflow aiming to acquire accurate and high-quality images in the context of the whole specimen. Multiple plant samples including rice, tobacco, Arabidopsis and maize were used to display the differences of phenotypes. Our work indicates that the XRM is a powerful tool to investigate plant microstructure in high-resolution scale. Our work also provides evidence that evaluate and quantify tissue specific differences for a range of plant species. We also characterize novel plant tissue phenotypes by the XRM, such as seeds in Arabidopsis, and utilize them for novel observation measurement. Our work represents an evaluated spatial and temporal resolution solution on seed observation and screening.

Converting Peanut Protein Biomass Waste into "Double Green" Meat Substitutes Using a High-Moisture Extrusion Process: A Multiscale Method to Explore a Process for Forming a Meat-Like Fibrous Structure.

Converting peanut protein biomass waste into environmentally friendly meat substitutes by a high-moisture extrusion process can help solve both resource and waste problems and be "double green". A multiscale method combined with some emerging techniques such as atomic force microscopy-based infrared spectroscopy and X-ray microscopy was used to make the whole extrusion process visible to show the process of forming a meat-like fibrous structure using two-dimensional and three-dimensional perspectives. The results showed that the protein molecules underwent dramatic structural changes and unfolded in the extruder barrel, which created favorable conditions for molecular rearrangement in the subsequent zones. It was confirmed that the meat-like fibrous structure started to form at the junction of the die and the cooling zone and that this structure was caused by the phase separation and rearrangement of protein molecules in the cooling zone. Moreover, the interactions between hydrogen bonds and disulfide bonds formed in the cooling zone maintained the meat-like fibrous structure with an α-helix > ß-sheet > ß-turn > random coil. Of the two main peanut proteins, arachin played a greater role in forming the fibrous structure than conarachin, especially those subunits of arachin with a molecular weight of 42, 39, and 22 kDa.

Three-Dimensionally Preserved Appendages in an Early Cambrian Stem-Group Pancrustacean.

Pancrustaceans boast impressive diversity, abundance, and ecological impact in the biosphere throughout the Phanerozoic [1]. Molecular clock estimates suggest an early Cambrian divergence for pancrustaceans [2, 3]. Despite the wealth of Palaeozoic exceptional fossiliferous deposits [4-7], the early evolution of Pancrustacea remains elusive given the difficulty of recognizing synapomorphies between Cambrian forms and extant representatives. Although early studies suggested crustacean affinities for Cambrian bivalved euarthropods [8-11], this view has fallen out of favor by recent reappraisals of their morphology [12-16]. The best evidence for total-group pancrustaceans comes from Cambrian microfossils preserved as three-dimensional phosphatic replicates in Orsten-type assemblages [4, 17-19] or as "small carbonaceous fossils" (SCFs) [20, 21]. Although these taphonomic windows capture minute morphology enabling detailed comparisons with extant representatives, these microfossils are limited to larval stages (Orsten) or recalcitrant fragmentary remains (SCFs) restricting their phylogenetic precision [5, 12, 19, 20, 22, 23]. We employed X-ray computed tomography [24] to reveal the three-dimensionally appendage morphology of the Chengjiang bivalved euarthropod Ercaicunia multinodosa [25] from the early Cambrian of China. E. multinodosa possesses characters uniquely shared with extant crustaceans, including differentiated tritocerebral antennae and epipodite-bearing biramous trunk appendages. Similarities between E. multinodosa with clypecaridids [9], waptiids [16] and hymenocarines [11, 14] suggest that these euarthropods may also possess similarly differentiated appendages, but these details are obstructed by the limits of preservation of compacted macrofossils. E. multinodosa illuminates the early evolution of pancrustacean appendage differentiation and represents the oldest unequivocal crown-group mandibulate known from complete macrofossils [22].

Insight Into the Pico- and Nano-Phytoplankton Communities in the Deepest Biosphere, the Mariana Trench.

As photoautotrophs, phytoplankton are generally present in the euphotic zone of the ocean, however, recently healthy phytoplankton cells were found to be also ubiquitous in the dark deep sea, i.e., at water depths between 2000 and 4000 m. The distributions of phytoplankton communities in much deeper waters, such as the hadal zone, are unclear. In this study, the vertical distribution of the pico- and nano-phytoplankton (PN) communities from the surface to 8320 m, including the epipelagic, mesopelagic, bathypelagic, and hadal zones, were investigated via both 18S and p23S rRNA gene analysis in the Challenger Deep of the Mariana Trench. The results showed that Dinoflagellata, Chrysophyceae, Haptophyta, Chlorophyta, Prochloraceae, Pseudanabaenaceae, Synechococcaceae, and Eustigmatophyceae, etc., were the predominant PN in the Mariana Trench. Redundancy analyses revealed that depth, followed by temperature, was the most important environmental factors correlated with vertical distribution of PN community. In the hadal zone, the PN community structure was considerably different from those in the shallower zones. Some PN communities, e.g., Eustigmatophyceae and Chrysophyceae, which have the heterotrophic characteristics, were sparse in shallower waters, while they were identified with high relative abundance (94.1% and 20.1%, respectively) at the depth of 8320 m. However, the dinoflagellates and Prochloraceae Prochlorococcus were detected throughout the entire water column. We proposed that vertical sinking, heterotrophic metabolism, and/or the transition to resting stage of phytoplankton might contribute to the presence of phytoplankton in the hadal zone. This study provided insight into the PN community in the Mariana Trench, implied the significance of phytoplankton in exporting organic matters from the euphotic to the hadal zone, and also hinted the possible existence of some undetermined energy metabolism (e.g., heterotrophy) of phytoplankton making themselves adapt and survive in the hadal environment.

Tensor-Based Angle Estimation Approach for Strictly Noncircular Sources with Unknown Mutual Coupling in Bistatic MIMO Radar.

In the paper, the estimation of joint direction-of-departure (DOD) and direction-of-arrival (DOA) for strictly noncircular targets in multiple-input multiple-output (MIMO) radar with unknown mutual coupling is considered, and a tensor-based angle estimation method is proposed. In the proposed method, making use of the banded symmetric Toeplitz structure of the mutual coupling matrix, the influence of the unknown mutual coupling is removed in the tensor domain. Then, a special enhancement tensor is formulated to capture both the noncircularity and inherent multidimensional structure of strictly noncircular signals. After that, the higher-order singular value decomposition (HOSVD) technology is applied for estimating the tensor-based signal subspace. Finally, the direction-of-departure (DOD) and direction-of-arrival (DOA) estimation is obtained by utilizing the rotational invariance technique. Due to the use of both noncircularity and multidimensional structure of the detected signal, the algorithm in this paper has better angle estimation performance than other subspace-based algorithms. The experiment results verify that the method proposed has better angle estimation performance.

Effect and mechanism of Salicornia bigelovii Torr. plant salt on blood pressure in SD rats.

In this paper, the effect and mechanism of Salicornia bigelovii Torr. plant salt (SPS) on blood pressure in Sprague Dawley (SD) rats were investigated. The results showed that the edible salt induced hypertension, but the SPS did not. Organ indices and Hematoxylin-Eosin (HE) staining analysis indicated that SPS had a protective effect on the kidney and liver. In comparison with the edible salt-treated group, nitric oxide (NO) content, angiotensin-II (Ang-II) and endothelin-1 (ET-1) levels in the serum of the SPS-treated group had no obvious changes, but serum creatinine concentration significantly decreased. Moreover, superoxide dismutase (SOD) and Na(+)-K(+)-ATPase activity increased while malondialdehyde (MDA) content decreased in the SPS-treated group. In conclusion, a long-term high salt intake could lead to hypertension. SPS, as a salt substitute, could increase the body's antioxidant ability to protect the kidney and liver from the damage caused by a high salt intake and effectively avoid the occurrence of hypertension.