The Sympatric Coexistence Mechanism: A Case Study of Two Penahia Species in the Beibu Gulf, South China Sea.

The study of trophic relationships among closely related species plays an important role in deepening our understanding of the resource utilization characteristics, differentiation patterns, and population dynamics of co-occurring species in the same habitat. This research uses two congeneric fish species, Pennahia pawak and Pennahia anea, as examples. Based on a stomach content analysis and a carbon-nitrogen stable isotope analysis, a comparative analysis of their feeding habits and trophic niches is conducted. Additionally, a spatial niche analysis is employed to explore the coexistence and competitive mechanisms between these two closely related fish species. The results show that specialized feeding habits mitigate intraspecific competition as the population densities increase. The carbon and nitrogen stable isotope analysis reveals variations in the feeding habits and trophic levels with body length, indicating adaptive shifts in prey selection. Despite similar food resources, niche differentiation arises due to differences in dominant prey, facilitating coexistence. Differences in spatial niche further contribute to niche separation and coexistence. In resource-limited environments, species such as Pennahia utilize trophic and spatial niche differentiation to collectively exploit resources and achieve coexistence, with implications for fishery management favoring Pennahia resource occupancy capabilities.

24-epibrassinolide improves cadmium tolerance and lateral root growth associated with regulating endogenous auxin and ethylene in Kentucky bluegrass.

The application of phytohormones is a viable technique to increase the efficiency of phytoremediation in heavy metal-contaminated soils. The objective of this study was to determine how the application of 24-epibrassinolide (EBR), a brassinosteroid analog, could regulate root growth and tolerance to cadmium (Cd) stress in Kentucky bluegrass. As a result, the number of lateral root primordia and total root length in the Cd-treated seedlings decreased by 33.1 % and 56.5 %, respectively. After the application of EBR, Cd accumulation in roots and leaves, and the negative effect of Cd on root growth were reduced under Cd stress. Additionally, the expression of the brassinosteroid signaling gene PpBRI1 was significantly upregulated by exogenous EBR. Moreover, exogenous EBR upregulated the expression of genes encoding antioxidant enzymes and improved the activity of antioxidant enzymes, thereby reduced oxidative stress in roots. Finally, targeted hormonomics analysis highlighted the utility of the application of EBR to alleviate the effect of Cd on the reduction in auxin (IAA) content and the increase in ethylene (ACC) content. These were known to be associated with the upregulation in the expression of auxin biosynthesis gene PpYUCCA1 and downregulation in the expression of ethylene biosynthesis gene PpACO1 in the roots treated with Cd stress. Overall, the application of EBR alleviated Cd-induced oxidative stress in addition to improving root elongation and lateral root growth crosstalk with auxin and ethylene in Kentucky bluegrass subjected to Cd stress. This study further highlights the potential role of brassinosteroids in improving the efficiency of phytoremediation for Cd-contaminated soils.

Influence of Curing Agent Amount on Properties of Dynamic Vulcanized Phenyl Silicone Rubber-SEBS-SBS System.

In this paper, we prepared a new type of thermoplastic vulcanizate (TPV) by melt blending methyl vinyl phenyl silicone rubber (PSR), styrene butylene copolymer (SBS), and hydrogenated SBS (SEBS) and then dynamically vulcanizing it. At the same time, we studied the influence of the content of the vulcanizing agent on the properties. The corresponding backscattered electron images were obtained by a scanning electron microscope (SEM) test of each group of samples, as well as the distribution of the PSR phase and the SEBS-SBS phase, and the vulcanization process of the samples with a vulcanizing agent content of 1 phr were characterized. According to the imaging principle of the backscattered electron signal, we found that the atomic number contrast can be clearly reflected in the backscattered image. From the obtained images, we found that PSR is a dispersed phase, while SEBS and SBS are continuous phases, that is, they had a "Sea-Island" structure. In the first 30 s of the vulcanization reaction, the "Sea-Island" structure is formed, and then the vulcanization reaction rate gradually slows down. We then printed the images and analyzed them using a colorimeter and found that it was feasible to quantitatively characterize the size of the compatible layer between the continuous and dispersed phases. According to the quantitative characterization results, we found that the silane coupling agent KH-172 can increase the thickness of the compatible layer by nearly 35%. In addition, we also tested the mechanical properties and low-temperature elastic properties of the material. Finally, we found that when the content of the vulcanizing agent was 1 phr, the elastic properties and tensile properties were the best, and when the content of the vulcanizing agent was more than 1 phr, the tensile and elastic properties of the material decreased significantly. At the same time, we also found that the addition of the silane coupling agent KH-172 can also significantly improve the tensile properties and elastic properties of TPV, which we believe is related to the increase in the thickness of the compatible layer. The test results of dynamic mechanics show that PSR has good compatibility with SEBS-SBS. When the vulcanizing agent content is less than or equal to 1 phr, the material exhibits good low-temperature resistance. In addition, through the test of the melt index of each group, it was also found that the addition of the vulcanizing agent will affect the fluidity of the melt to a certain extent. When the content of the vulcanizing agent is greater than 1 phr, the melt fluidity decreases more obviously.

Comparative transcriptome analysis of resistant and susceptible Kentucky bluegrass varieties in response to powdery mildew infection.

BACKGROUND: Poa pratensis is one of the most common cold-season turfgrasses used for urban turf building, and it is also widely used in ecological environment management worldwide. Powdery mildew is a common disease of P. pratensis. To scientifically and ecologically control lawn powdery mildew, the molecular mechanism underlying the response of P. pratensis to powdery mildew infection must better understood. RESULTS: To explore molecular mechanism underlying the response of P. pratensis to powdery mildew infection, this study compared physiological changes and transcriptomic level differences between the highly resistant variety 'BlackJack' and the extremely susceptible variety 'EverGlade' under powdery mildew infection conditions. We analyzed DEGs using reference canonical pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and the results showed that "starch and sucrose metabolism", "photosynthesis" and "fatty acid metabolism"pathways were only enriched in 'BlackJack', and the expression of DEGs such as HXK, INV, GS, SS, AGpase and ß-amylase in "starch and sucrose metabolism" pathway of 'BlackJack' were closely related to powdery mildew resistance. Meanwhile, compared with 'EverGlade', powdery mildew infection promoted synthesis of sucrose, expression of photosynthesis parameters and photosynthesis-related enzymes in leaves of 'BlackJack' and decreased accumulation of monosaccharides such as glucose and fructose. CONCLUSIONS: This study identified the key metabolic pathways of a P. pratensis variety with high resistance to powdery mildew infection and explored the differences in physiological characteristics and key genes related to sugar metabolism pathways under powdery mildew stress. These findings provide important insights for studying underlying molecular response mechanism.

Species Composition, Growth, and Trophic Traits of Hairtail (Trichiuridae), the Most Productive Fish in Chinese Marine Fishery.

Hairtail (Scombriformes: Trichiuridae) have always ranked first in single-species production in Chinese marine fishery. However, due to the confusion of species identification, in official statistics, data on hairtail production and economic value are a combination of all the different species of Trichiuridae. In this study, based on sampling along China's coastal areas, the composition and distribution of common hairtail species, as well as their age, growth, and trophic traits, are discussed. Six species of four genera and two subfamilies were identified, and largehead hairtail (Trichiurus japonicus) and Savalai hairtail (Lepturacanthus savala) were the most important populations that constituted catch production. The growth parameter b could be divided into two groups, with values in species mostly inhabiting northern parts of Chinese seas higher than those in southern parts. Most individuals were 1-2 years of age, suggesting species sexual precocity and individual miniaturization under multiple stresses. Species of Trichiuridae are at the top of the food web and play a bottom-up role in regulating the trophic dynamics of marine food webs. Largehead hairtail showed the highest stability and the greatest impact on the stability of the trophic structure. Despite temporary resource maintenance under fishery-induced evolution, the effective recovery and reasonable utilization of hairtail resources are still the main focuses of attention for Chinese marine fishery.

A Morphological Study of Dynamically Vulcanized Styrene-Ethylene-Butylene-Styrene/Styrene-Butylene-Styrene/MethylVinylSilicon Rubber Thermoplastic Elastomer.

In this work, we prepared thermoplastic silicone rubber (TPSiV) by dynamically vulcanizing different relative proportions of methyl vinyl silicone rubber (MVSR), styrene ethylene butene styrene block copolymer (SEBS), and styrene butadiene styrene block copolymer (SBS). The compatibility and distribution of the MVSR phase and SEBS/SBS phase were qualitatively characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) tests on TPSiV. Subsequently, the backscattered electron signal image was analyzed using a colorimeter, and it was found that the size of the interface layer between the MVSR phase and the SEBS-SBS phase could be quantitatively characterized. This method overcomes the defect of the etching method, which cannot quantitatively analyze the size of the compatible layer between the two polymers. The final experiment proved that the two phases in TPSiV exhibited a "sea-island" structure, in which the MVSR phase acted as a dispersed phase in the SEBS-SBS phase. In addition, the addition of the silane coupling agent KH-907 (γ-isocyanatopropyltriethoxysilane) improved the mechanical properties of TPSiV, increasing the tensile strength by about 40% and the elongation at break by 30%. The permanent tensile deformation increase rate was about 15%. Through the quantitative measurement of the compatible layer, it was found that KH-907 could increase the thickness of the interface layer between the MVSR phase and the SEBS-SBS phase by more than 30%, which explained why the silane coupling agent KH-907 improved the mechanical properties of TPSiV at the micro level.

Physiological and transcriptome analysis of Poa pratensis var. anceps cv. Qinghai in response to cold stress.

BACKGROUND: Low temperature limits the growth and development and geographical distribution of plants. Poa pratensis is a cool-season turfgrass mainly grown in urban areas. However, low winter temperature or cold events in spring and autumn may cause P.pratensis mortality, affecting the appearance of lawns. P.pratensis var. anceps cv. Qinghai (PQ) is widely distributed in the Qinghai-Tibet Plateau above 3000 m. PQ has greater cold tolerance than the commercially cultivated P.pratensis varieties. However, existing studies on the response mechanism of PQ to low temperatures have mainly focused on physiological and biochemical perspectives, while changes in the PQ transcriptome during the response to cold stress have not been reported. RESULTS: To investigate the molecular mechanism of the PQ cold response and identify genes to improve the low-temperature tolerance of P.pratensis, we analyzed and compared the transcriptomes of PQ and the cold-sensitive P.pratensis cv. 'Baron' (PB) under cold stress using RNA sequencing. We identified 5996 and 3285 differentially expressed genes (DEGs) between the treatment vs control comparison of PQ and PB, respectively, with 5612 DEGs specific to PQ. Based on the DEGs, important Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, such as "starch and sucrose metabolism", "protein processing in endoplasmic reticulum", "phenylalanine metabolism" and "glycolysis/gluconeogenesis" were significantly enriched in PQ, and "starch and sucrose metabolism", "phenylpropanoid biosynthesis", "galactose metabolism" and "glutathione metabolism" were significantly enriched in PB. In addition, the "glycolysis" and "citrate cycle (TCA cycle)" pathways were identified as involved in cold tolerance of P.pratensis. CONCLUSIONS: As we know, this is the first study to explore the transcriptome of P.pratensis var. anceps cv. Qinghai. Our study not noly provides important insights into the molecular mechanisms of P.pratensis var. anceps cv. Qinghai responds to cold stress, but also systematically reveals the changes of key genes and products of glycolysis and TCA cycle in response to cold stress, which is conductive to the breeding of cold-tolerance P.pratensis genotype.

[Functional diversity of fishes in the Minjiang Estuary, Southeast China]. / é—½æ±Ÿå£é±¼ç±»åŠŸèƒ½å¤šæ ·æ€§.

Based on samples collected by bottom trawl in May, August, November and December 2016 in the Minjiang Estuary, species richness and functional diversity of fishes, as well as their spatial-temporal variations, were quantified by a trait-based approach. The functional diversity varied with the changes of species richness. The species richness averaged across all stations were (17.8±5.1) species in spring, (22.4±5.6) in summer, (17.7±6.3) in autumn, and (12.1±2.3) in winter. Functional diversity also showed seasonal variation, with the highest in summer as (33.94±28.70), followed by (9.93±8.83) in winter, (11.30±7.55) in spring and (19.05±19.32) in autumn. The key functional species varied seasonally, as Setipinna taty contributing to 26% of the total functional value in spring, Polydactylus sextarius at 26% in summer, Harpadon nehereus climbing to 69% in autumn, and Collichthys lucidus at 38% in winter. The seasonal variations of fish species function were determined by life history and its interaction with other species.

Integrating quantum key distribution with classical communications in backbone fiber network.

Quantum key distribution (QKD) provides information-theoretic security based on the laws of quantum mechanics. The desire to reduce costs and increase robustness in real-world applications has motivated the study of coexistence between QKD and intense classical data traffic in a single fiber. Previous works on coexistence in metropolitan areas have used wavelength-division multiplexing, however, coexistence in backbone fiber networks remains a great experimental challenge, as Tbps data of up to 20 dBm optical power is transferred, and much more noise is generated for QKD. Here we present for the first time, to the best of our knowledge, the integration of QKD with a commercial backbone network of 3.6 Tbps classical data at 21 dBm launch power over 66 km fiber. With 20 GHz pass-band filtering and large effective core area fibers, real-time secure key rates can reach 4.5 kbps and 5.1 kbps for co-propagation and counter-propagation at the maximum launch power, respectively. This demonstrates feasibility and represents an important step towards building a quantum network that coexists with the current backbone fiber infrastructure of classical communications.

Experimental demonstration of 1.08 Tb/s PDM CO-SCFDM transmission over 3170 km SSMF.

Coherent optical single-carrier frequency-division-multiplexing (CO-SCFDM) is a promising candidate for future high-speed long-haul optical fiber transmission system. Being a modified form of coherent optical orthogonal frequency division multiplexing (CO-OFDM), the CO-SCFDM can inherit the advantages such as low computation complexity and high flexibility, while suffers less nonlinear impairment due to much lower peak-to-average power ratio (PAPR). In this paper, we experimentally demonstrate 1.08 Tb/s polarization-division multiplexing (PDM) CO-SCFDM transmission over 3170 km standard single-mode fiber (SSMF) with Erbium-doped fiber amplifier (EDFA) only. The back-to-back and nonlinear transmission performances for CO-OFDM and CO-SCFDM are also compared.