摘要：
Abstract Diatoms are a type of photosynthetic phytoplankton that can acclimate to the light level of their environment. Diatoms from different habitats exhibit different photoacclimation characteristics; those from relatively low-light intensity habitats present relatively high photosynthetic activity, high light-harvesting pigment (Chla) content, and low xanthophyll content. Conversely, diatoms from high-light intensity environments have lower photosynthetic activity, less Chla content, and efficient xanthophyll cycling. Hence, diatoms can maintain high growth and photosynthetic activity within a wide range of light intensities. Whether the mechanisms of such adaptability are a consequence of biological photoacclimation to different light intensities or interspecific differences is unknown. Here, we show that differences in photoacclimation ability are more significant than species differences. We found similar species compositions in low- and high-light habitats of the Hanjiang River, China; however, there were remarkable differences in rapid light-response curve parameters. The photoacclimation of algae and trends in their photosynthetic activity can be estimated by rapid detection techniques. We isolated three diatom species common to both habitats and grew them under various light intensities, finding that they have an excellent ability to acclimate to local light conditions. Diatoms can use physiological strategies to handle light fluctuations, but only for short periods. Our results provide a theoretical basis for controlling algal blooms through light management. With knowledge of the photoacclimation characteristics of diatoms and according to the availability of local water conservancy facilities, it is possible to use light management to control diatom blooms more efficiently than with conventional techniques, thereby reducing water usage.
摘要：
Abstract The mitochondrial genome of one potamidae species Neilupotamon papileonaceum was sequenced and annotated. The mitogenome is 16,273 bp in length, containing 37 typical genes. The A + T content of the whole mitogenome is 68.9%. Most of the PCGs started with ATG and stopped with TAT, except for ATP8 and ND6 stopped with TGA, COX1, COX2, ND5, ND4, and ND4L used incomplete T as stop codon. The phylogeny tree is monophyletic among 15 related species. The relationships of N. papileonaceum, Sinopotamon yaanense, and Longpotamon yangtsekiense were closer than others. This study further enriched mitogenome database of the tribe Typhlocybini.
摘要：
Monitoring the ecological status of drinking water reservoirs is very important for assessing risks to the safety of drinking water supplies. Because of the huge number of potential organic and inorganic contaminants in water, we focused our study on common water quality variables and three ecological indices. In this study, we used the modified Carlson trophic status index, Shannon diversity index, and the phytoplankton functional group index to assess the changing ecological status of Zhushuqiao Reservoir, a drinking water source in central China. Stratified water sampling for abiotic and biotic variables was conducted bimonthly from April 2016 to February 2017. All three indices indicated that upper reservoir water quality and ecological condition were worse than those in the lower reservoir. Also, the dominant phytoplankton species in the upper reservoir differed significantly from those in the lower reservoir. The reservoir was eutrophic from June to October, especially in June. During the other months, it was mesotrophic, with the best water quality in winter. Water temperature was the main driver of seasonal changes in both biotic and abiotic indicators, although hydrological condition also affected water quality. Total phosphorus (TP) was the limiting factor for phytoplankton, but phytoplankton biomass increased greatly when both TP and total nitrogen increased. Each index had weaknesses; but applying all three together yielded a comprehensive ecological assessment of Zhushuqiao Reservoir and could do so for other similar reservoirs.
摘要：
Genetic diversity is an important component of biodiversity and investigating and protecting the wild genetic diversity of species has always been an important research topic in conservation biology. Due to habitat destruction and over catching, wild Chinese soft-shell turtles (Pelodiscus spp.) have been severely damaged, resulting in the species being listed on the IUCN Red List of Threatened Species in 2000. However, only few studies with contradictory results on the genetic diversity of Pelodiscus turtles have been reported. To investigate the genetic diversity and population structure of Pelodiscus turtles, 123 specimens were collected from five localities in East Asia, and their genetic variation was analyzed on the basis of a 922-bp partial sequence of the mitochondrial cytb gene. Forty-nine polymorphic sites were detected, revealing 56 haplotypes. A pattern of high haplotype diversity (Hd = 0.994) and nucleotide diversity (pi = 0.01655) was found in the examined range. A maximum likelihood phylogenetic tree and median-joining network analyses indicated that the Pelodiscus turtles divided in four populations throughout East Asia, and the Pelodiscus turtles probably originate from the Yangtze River and was introduced to Yellow River, Taiwan, and Japan through Xijiang River. These results served a helpful resource for conservation of Pelodiscus turtles.
摘要：
Schizothorax prenanti (S. prenanti) is an indigenous fish species and is popularly cultured in southwestern China. In recent years, intensive farming of S. prenanti and water quality deterioration has increased the susceptibility of this fish to various pathogens, including Aeromonas hydrophila (A. hydrophila), which has caused severe damage to S. prenanti production. However, the understanding of molecular immune response of S. prenanti to A. hydrophila infection is still lacking. In order to better comprehend the S. prenanti time series immune response process against A. hydrophila, we conducted the first transcriptomic comparison in S. prenanti spleen at 4, 24, and 48 h after the infection challenge of A. hydrophila against their control counterparts. In total, 628 million clean reads were obtained from 18 libraries and assembled into 262,745 transcripts. After eliminating sequence redundancy, 69,373 unigenes with an average length of 1476 bp were obtained. Comparative analysis revealed 1890 unigenes with significantly differential expression, including 172, 455, 589 upregulated and 27, 676, 551 unigenes downregulated genes for 4, 24, and 48 h post-infection, respectively. Differentially expressed genes (DEGs) were validated using qPCR for 15 randomly selected genes. Enrichment and pathway analysis of DEGs was carried out to understand the functions of the immune-related genes. Our results revealed that many important functional genes relating to complement and coagulation cascades, chemokine signaling pathway, toll-like receptor signaling pathway, NOD-like receptor signaling pathway and leukocyte transendothelial migration were regulated during the infection of A. hydrophila, and the expression of those genes reflected the transcriptome profiles during the challenging stages.
