Transcriptional Homeostasis of a Mangrove Species, Ceriops tagal, in Saline Environments, as Revealed by Microarray Analysis

<div><h3>Background</h3><p>Differential responses to the environmental stresses at the level of transcription play a critical role in adaptation. Mangrove species compose a dominant community in intertidal zones and form dense forests at the sea-land interface, and although the anatomical and physiological features associated with their salt-tolerant lifestyles have been well characterized, little is known about the impact of transcriptional phenotypes on their adaptation to these saline environments.</p> <h3>Methodology and Principal findings</h3><p>We report the time-course transcript profiles in the roots of a true mangrove species, <em>Ceriops tagal</em>, as revealed by a series of microarray experiments. The expression of a total of 432 transcripts changed significantly in the roots of <em>C. tagal</em> under salt shock, of which 83 had a more than 2-fold change and were further assembled into 59 unigenes. Global transcription was stable at the early stage of salt stress and then was gradually dysregulated with the increased duration of the stress. Importantly, a pair-wise comparison of predicted homologous gene pairs revealed that the transcriptional regulations of most of the differentially expressed genes were highly divergent in <em>C. tagal</em> from that in salt-sensitive species, <em>Arabidopsis thaliana</em>.</p> <h3>Conclusions/Significance</h3><p>This work suggests that transcriptional homeostasis and specific transcriptional regulation are major events in the roots of <em>C. tagal</em> when subjected to salt shock, which could contribute to the establishment of adaptation to saline environments and, thus, facilitate the salt-tolerant lifestyle of this mangrove species. Furthermore, the candidate genes underlying the adaptation were identified through comparative analyses. This study provides a foundation for dissecting the genetic basis of the adaptation of mangroves to intertidal environments.</p> </div

DNA barcoding reveals insect diversity in the mangrove ecosystems of the Hainan Island, China

Insect diversity is an indicator of environmental conditions. Frequent outbreaks of mangrove pests have threatened the fragile mangrove ecosystem in China and the sustainable utilization of mangrove resources. The understanding of mangrove pests as well as a fundamental knowledge of insect diversity in mangrove forests in China has been hindered by the difficulty of morphological species delimitation because captured insect specimens are either larvae or incompletely-preserved adults. DNA barcoding technology uses only a small amount of DNA to conduct species identification. Taking advantage of this, we investigated the entomofauna of mangrove forests in Hainan island by using a barcode combining cytochrome c oxidase subunit I (COI) and cytochrome-b (Cytb). We collected 627 specimens at six localities around the island, which were identified as 219 insect species belonging to 11 orders and 72 families. Lepidoptera, Coleoptera, and Hymenoptera are the most species-rich and abundant taxa. We also identified 13 mangrove pests, five parasitoids, and 12 species of predators.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Population subdivision promoted by a sea-level-change-driven bottleneck: A glimpse from the evolutionary history of the mangrove plant Aegiceras corniculatum

Historic climate changes drive geographical populations of coastal plants to contract and recover dynamically, even die out completely. Species suffering from such bottlenecks usually lose intraspecific genetic diversity, but how do these events influence population subdivision patterns of coastal plants? Here, we investigated this question in the typical coastal plant: mangrove species Aegiceras corniculatum. Inhabiting the intertidal zone of the tropical and subtropical coast of the Indo-West Pacific oceans, its populations are deemed to be greatly shaped by historic sea-level fluctuations. Using dual methods of Sanger and Illumina sequencing, we found that the 18 sampled populations were structured into two groups, namely, the "Indo-Malayan" group, comprising three subgroups (the northern South China Sea, Gulf of Bengal, and Bali), and the "Pan-Australasia" group, comprising the subgroups of the southern South China Sea and Australasia. Based on the approximate Bayesian computations and Stairway Plot, we inferred that the southern South China Sea subgroup, which penetrates the interior of the "Indo-Malayan" group, originated from the Australasia subgroup, accompanied by a severe bottleneck event, with a spot of gene flow from both the Australasia and "Indo-Malayan" groups. Geographical barriers such as the Sundaland underlie the genetic break between Indian and Pacific Oceans, but the discontinuity between southern and northern South China Sea was originated from genetic drift in the bottleneck event. Hence, we revealed a case evidencing that the bottleneck event promoted population subdivision. This conclusion may be applicable in other taxa beyond coastal plants

Rethinking the Zigzag Flattening for Image Reading

Sequence ordering of word vector matters a lot to text reading, which has been proven in natural language processing (NLP). However, the rule of different sequence ordering in computer vision (CV) was not well explored, e.g., why the "zigzag" flattening (ZF) is commonly utilized as a default option to get the image patches ordering in vision transformers (ViTs). Notably, when decomposing multi-scale images, the ZF could not maintain the invariance of feature point positions. To this end, we investigate the Hilbert fractal flattening (HF) as another method for sequence ordering in CV and contrast it against ZF. The HF has proven to be superior to other curves in maintaining spatial locality, when performing multi-scale transformations of dimensional space. And it can be easily plugged into most deep neural networks (DNNs). Extensive experiments demonstrate that it can yield consistent and significant performance boosts for a variety of architectures. Finally, we hope that our studies spark further research about the flattening strategy of image reading

Effect of the Internal Humidity of Concrete on Frost Resistance and Air Void Structure under Different Low Temperature Conditions

From the perspective of combining macroscopic and microscopic properties, this paper simulates the freeze&ndash;thaw cycle process at different freezing low temperatures based on the climate simulation equipment and by setting the curing conditions with different temperatures and relative humidity to produce different moisture conditions in concrete. The frost resistance properties and microscopic air void performance of concrete with different internal water content under different freezing low temperatures in freeze&ndash;thaw cycles were systematically studied. The results show that the higher the internal water content of concrete, the more obvious the mass loss rate and dynamic elastic modulus loss of concrete in the freeze&ndash;thaw process, and the more serious the deterioration of the air void parameter performance of the air-entraining agent introduced into concrete, which is manifested as the average bubble diameter and bubble spacing factor become larger and the bubble specific surface area decreases. In addition, in the case of the same internal moisture content of concrete, the freezing temperature used in the freeze&ndash;thaw cycle also has an important impact on the frost resistance of concrete and air void parameters; the lower the freezing temperature used, the more significant the decline in the frost resistance of concrete, the more obvious the deterioration of air void parameters

Effects of Pleistocene sea-level fluctuations on mangrove population dynamics: a lesson from Sonneratia alba

Abstract Background A large-scale systematical investigation of the influence of Pleistocene climate oscillation on mangrove population dynamics could enrich our knowledge about the evolutionary history during times of historical climate change, which in turn may provide important information for their conservation. Results In this study, phylogeography of a mangrove tree Sonneratia alba was studied by sequencing three chloroplast fragments and seven nuclear genes. A low level of genetic diversity at the population level was detected across its range, especially at the range margins, which was mainly attributed to the steep sea-level drop and associated climate fluctuations during the Pleistocene glacial periods. Extremely small effective population size (Ne) was inferred in populations from both eastern and western Malay Peninsula (44 and 396, respectively), mirroring the fragility of mangrove plants and their paucity of robustness against future climate perturbations and human activity. Two major genetic lineages of high divergence were identified in the two mangrove biodiversity centres: the Indo-Malesia and Australasia regions. The estimated splitting time between these two lineages was 3.153 million year ago (MYA), suggesting a role for pre-Pleistocene events in shaping the major diversity patterns of mangrove species. Within the Indo-Malesia region, a subdivision was implicated between the South China Sea (SCS) and the remaining area with a divergence time of 1.874 MYA, corresponding to glacial vicariance when the emerged Sunda Shelf halted genetic exchange between the western and eastern coasts of the Malay Peninsula during Pleistocene sea-level drops. Notably, genetic admixture was observed in populations at the boundary regions, especially in the two populations near the Malacca Strait, indicating secondary contact between divergent lineages during interglacial periods. These interregional genetic exchanges provided ample opportunity for the re-use of standing genetic variation, which could facilitate mangrove establishment and adaptation in new habitats, especially in the context of global climate changes. Conclusion Phylogeogrpahic analysis in this study reveal that Pleistocene sea-level fluctuations had profound influence on population differentiation of the mangrove tree S. alba . Our study highlights the fragility of mangrove plants and offers a guide for the conservation of coastal mangrove communities experiencing ongoing changes in sea-level

Colloidal self-assembly based ultrathin metasurface for perfect absorption across the entire visible spectrum

Perfect absorption over the entire visible spectrum can create a dark background for acquiring images with high contrast and improved resolution, which is crucial for various applications such as medical imaging, biological detection, and industrial non-destructive testing. The broadband absorption is desired to be achieved in an ultrathin structure for low noise as well as high integration. Here, we experimentally demonstrate a metasurface broadband perfect absorber with an ultrathin thickness of 148 nm and a large area of ∼10 cm2. Such a metasurface, with more than 97% absorption in the wavelength range from 400 to 800 nm, is composed of chromium nanodisk hexagonal array deposited on a chromium substrate with a silica spacer. A self-assembly based colloidal lithography nanofabrication method is developed for the scalable fabrication of the proposed nanostructure. We attribute the broadband absorption to the spectrally overlapped Fabry–Perot resonance, surface plasmon polariton, and localized surface plasmon resonances. Our results offer a novel approach to wafer-scale and low-cost manufacturing of absorption-based devices for applications such as high-contrast imaging and optical modulation