Institute of Hydrobiology, Chinese Academy Of Sciences
Not a member yet
20118 research outputs found
Sort by
Elevation shapes biodiversity patterns through metacommunity-structuring processes
No full textStochastic (e.g., via species dispersal and ecological drift) and deterministic (e.g., via environmental and biotic filtering) processes can produce diversity patterns related to changes in elevation. However, existing studies have not generally examined these processes within a compressive framework. Stream macroinvertebrates are an important and diverse component of freshwater environments in high-mountain systems. By considering metacommunity-structuring processes using Hierarchical Modelling of Species Communities (HMSC), we investigated changes in taxon richness of stream macroinvertebrates along elevational gradients in streams of the Cangshan mountain range in Southwest China. We found that increasing taxon richness along the elevation gradient until the optimum was reached could be modeled using the integrated actions of full structuring processes within the metacommunity modeling. Consistent increases in taxon-richness along the elevation gradient were able to be modeled considering environmental filtering alone. In addition, the importance of structuring processes on shaping communities decreased along spatial hierarchical-scales (from local habitat to mountain-aspect levels). These results suggest that stochastic and biotic-filtering processes can confound environmental filtering in shaping macroinvertebrate communities in high-mountain streams. A comprehensive understanding of the mechanisms underlying elevational biodiversity patterns of riverine communities can be improved through quantitative frameworks (e.g., HMSC) linking metacommunity theory to the real-world systems. (C) 2020 Elsevier B.V. All rights reserved
Expression from DIF1-motif promoters of hetR and patS is dependent on HetZ and modulated by PatU3 during heterocyst differentiation
No full textHetR and PatS/PatX-derived peptides are the activator and diffusible inhibitor for cell differentiation and patterning in heterocyst-forming cyanobacteria. HetR regulates target genes via HetR-recognition sites. However, some genes (such as patS/patX) upregulated at the early stage of heterocyst differentiation possess DIF1 (or DIF+) motif (TCCGGA) promoters rather than HetR-recognition sites; hetR possesses both predicted regulatory elements. How HetR controls heterocyst-specific expression from DIF1 motif promoters remains to be answered. This study presents evidence that the expression from DIF1 motif promoters of hetR, patS and patX is more directly dependent on hetZ, a gene regulated by HetR via a HetR-recognition site. The HetR-binding site upstream of hetR is not required for the autoregulation of hetR. PatU3 (3' portion of PatU) that interacts with HetZ may modulate the expression of hetR, hetZ and patS. These findings contribute to understanding of the mutual regulation of hetR, hetZ-patU and patS/patX in a large group of multicellular cyanobacteria
Evaluating toxicity impacts of environmental exposed chromium on small Indian mongoose (Urva auropunctatus) hematological, biochemical and histopathological functioning
No full textSub-lethal toxic impacts of chromium on hematological, biochemical and histological parameters were analyzed in the female small Indian mongoose (Urva auropuctatus) residing contaminated environment of tannery industry. Chromium bioaccumulation in the blood, liver and kidney tissue of the exposed mongooses was found elevated compared to the control mongooses' tissues. Total body weight (75.7%), liver weight (83.6%) as well as HSI (68.1%), RSI (86.2%) and the platelets counts (59.7%) were found significantly elevated, with significantly reduced RBCs (59.6%), and WBCs (64%). LFT and RFT were also found abnormal, moreover, the histopathological injuries had been distinct inside the kidney (>75%) and hepatic (>75%) tissues of exposed animals. Shrinkage and vacuolization (> 75%) inside the hepatocyte expanded sinusoidal spaces and nuclear pyknosis (>75%) was evident within the hepatic tissue. Hypertrophy of epithelial cells of renal tubules and inter-renal cells of the head kidney with a reduction in tubular lumens (>75%) and vacuolization of tubules were witnessed within the kidney section. Atrophy inside the kidney inter-renal cells, glomeruli compression within the Bowman's capsules (>75%) following the necrosis in hematopoietic tissues were found in exposed animals. The present findings indicate that chronic exposure to chromium induces severe anemia, decreased serum protein concentration, hepatic and renal tissue histopathology, impairing the vital capabilities of liver, metabolic regulation, excretion, and stress homeostasis maintenance of which within the long-run may posture a severe risk to animal well-being then distress their inhabitants. (C) 2020 Elsevier Ltd. All rights reserved
Production of Highly Active Extracellular Amylase and Cellulase FromBacillus subtilisZIM3 and a Recombinant Strain With a Potential Application in Tobacco Fermentation
No full textIn this study, a series of bacteria capable of degrading starch and cellulose were isolated from the aging flue-cured tobacco leaves. Remarkably, there was a thermophilic bacterium,Bacillus subtilisZIM3, that can simultaneously degrade both starch and cellulose at a wide range of temperature and pH values. Genome sequencing, comparative genomics analyses, and enzymatic activity assays showed that the ZIM3 strain expressed a variety of highly active plant biomass-degrading enzymes, such as the amylase AmyE1 and cellulase CelE1. Thein vitroand PhoA-fusion assays indicated that these enzymes degrading complex plant biomass into fermentable sugars were secreted into ambient environment to function. Besides, the amylase and cellulase activities were further increased by three- to five-folds by using overexpression. Furthermore, a fermentation strategy was developed and the biodegradation efficiency of the starch and cellulose in the tobacco leaves were improved by 30-48%. These results reveal thatB. subtilisZIM3 and the recombinant strain exhibited high amylase and cellulase activities for efficient biodegradation of starch and cellulose in tobacco and could potentially be applied for industrial tobacco fermentation
Regulation and remodeling of intermediate metabolite and membrane lipid during NaCl-induced stress in freshwater microalgaMicractiniumsp. XJ-2 for biofuel production
No full textMicroalgae can accumulate a large fraction of reduced carbon as lipids under NaCl stress. This study investigated the mechanism of carbon allocation and reduction and triacylglycerol (TAG) accumulation in microalgae under NaCl-induced stress.Micractiniumsp. XJ-2 was exposed to NaCl stress and cells were subjected to physiological, biochemical, and metabolic analyses to elucidate the stress-responsive mechanism. Lipid increased with NaCl concentration after 0-12 hr, then stabilized after 12-48 hr, and finally decreased after 48-72 hr, whereas TAG increased (0-48 hr) and then decreased (48-72 hr). Under NaCl-induced stress at lower concentrations, TAG accumulation, at first, mainly shown to rely on the carbon fixation through photosynthetic fixation, carbohydrate degradation, and membrane lipids remodeling. Moreover, carbon compounds generated by the degradation of some amino acids were reallocated and enhanced fatty acid synthesis. The remodeling of the membrane lipids of NaCl-induced microalgae relied on the following processes: (a) Increase in the amount of phospholipids and reduction in the amount of glycolipids and (b) extension of long-chain fatty acids. This study enhances our understanding of TAG production under NaCl stress and thus will provide a theoretical basis for the industrial application of NaCl-induced in the microalgal biodiesel industry
Regain of sex determination system and sexual reproduction ability in a synthetic octoploid male fish
No full textPolyploids in vertebrates are generally associated with unisexual reproduction, but the direct consequences of polyploidy on sex determination system and reproduction mode remain unknown. Here, we synthesized a group of artificial octoploids between unisexual gynogenetic hexaploidCarassius gibelioand sexual tetraploidCarassius auratus. The synthetic octoploids were revealed to have more than 200 chromosomes, in which 50 chromosomes including the X/Y sex determination system were identified to transfer from sexual tetraploidC. auratusinto the unisexual gynogenetic hexaploidC. gibelio. Significantly, a few synthetic octoploid males were found to be fertile, and one octoploid male was confirmed to regain sexual reproduction ability, which exhibits characteristics that are the same to sexual reproduction tetraploid males, such as 1:1 sex ratio occurrence, meiosis completion and euploid sperm formation in spermatogenesis, as well as normal embryo development and gene expression pattern during embryogenesis. Therefore, the current finding provides a unique case to explore the effect of sex determination system incorporation on reproduction mode transition from unisexual gynogenesis to sexual reproduction along with genome synthesis of recurrent polyploidy in vertebrates
Regain of sex determination system and sexual reproduction ability in a synthetic octoploid male fish
No full textPolyploids in vertebrates are generally associated with unisexual reproduction, but the direct consequences of polyploidy on sex determination system and reproduction mode remain unknown. Here, we synthesized a group of artificial octoploids between unisexual gynogenetic hexaploidCarassius gibelioand sexual tetraploidCarassius auratus. The synthetic octoploids were revealed to have more than 200 chromosomes, in which 50 chromosomes including the X/Y sex determination system were identified to transfer from sexual tetraploidC. auratusinto the unisexual gynogenetic hexaploidC. gibelio. Significantly, a few synthetic octoploid males were found to be fertile, and one octoploid male was confirmed to regain sexual reproduction ability, which exhibits characteristics that are the same to sexual reproduction tetraploid males, such as 1:1 sex ratio occurrence, meiosis completion and euploid sperm formation in spermatogenesis, as well as normal embryo development and gene expression pattern during embryogenesis. Therefore, the current finding provides a unique case to explore the effect of sex determination system incorporation on reproduction mode transition from unisexual gynogenesis to sexual reproduction along with genome synthesis of recurrent polyploidy in vertebrates
Four New Members of Foliicolous Green Algae Within the Watanabea Clade (Trebouxiophyceae, Chlorophyta) from China
No full textMembers of the Watanabea clade of Trebouxiophyceae are genetically diverse and widely distributed in all kinds of habitats, especially in most terrestrial habitats. Ten new strains of terrestrial algae isolated from the tropical rainforest in China, and four published strains were investigated in this study. Morphological observation and molecular phylogenetic analyses based on the 18S, ITS, rbcL, and tufA genes were used to identify the new strains. Four previously described species were reinvestigated to supplement molecular data and autospores' morphological photographs. The phylogenetic analyses based on 18S only, the concatenated dataset of 18S and ITS, as well as the concatenated dataset of rbcL and tufA, showed the same phylogenetic positions and relationships of these new strains. According to the phylogenetic analysis and morphological comparisons results, we described these 10 strains as four new members within the Watanabea clade, Polulichloris yunnanensis sp. nov., Polulichloris ovale sp. nov., Massjukichlorella orientale sp. nov., and Massjukichlorella minus sp. nov., and two known species, Massjukichlorella epiphytica, and Mysteriochloris nanningensis. Additionally, we provide strong evidence proving that Phyllosiphon, Mysteriochloris, Polulichloris, and Desertella all reproduce through unequal sized autospores
Performance evaluation of MBR in treating microplastics polyvinylchloride contaminated polluted surface water
No full textThe microplastics removal and its effects on membrane fouling in membrane bioreactor (MBR) for treating polluted surface water in drinking purpose was investigated in this study. Typical microplastics polyvinylchloride (PVC) with concentration 10 particles/L was added in the feed water. MBR was effective in treating organic matters and ammonia with removal rate over 80% and 95%, respectively. The removal performance was immediately inhibited with the microplastics PVC added into the MBR system, and recovered after operated for few days. The membrane fouling and cleaning results indicated that microplastics contamination could led to higher membrane fouling, and also the irreversible membrane fouling. The main contributor of rejection is the membrane module and the adsorption onto bio-carrier. The microbial community of the system before and after PVC addition did not show obvious difference. MBR has the potential to be used as effective technology in treating microplastics contaminated polluted surface water.</p
A genomics approach reveals the global genetic polymorphism, structure, and functional diversity of ten accessions of the marine model diatom Phaeodactylum tricornutum
No full textDiatoms emerged in the Mesozoic period and presently constitute one of the main primary producers in the world's ocean and are of a major economic importance. In the current study, using whole genome sequencing of ten accessions of the model diatom Phaeodactylum tricornutum, sampled at broad geospatial and temporal scales, we draw a comprehensive landscape of the genomic diversity within the species. We describe strong genetic subdivisions of the accessions into four genetic clades (A-D) with constituent populations of each clade possessing a conserved genetic and functional makeup, likely a consequence of the limited dispersal of P. tricornutum in the open ocean. We further suggest dominance of asexual reproduction across all the populations, as implied by high linkage disequilibrium. Finally, we show limited yet compelling signatures of genetic and functional convergence inducing changes in the selection pressure on many genes and metabolic pathways. We propose these findings to have significant implications for understanding the genetic structure of diatom populations in nature and provide a framework to assess the genomic underpinnings of their ecological success and impact on aquatic ecosystems where they play a major role. Our work provides valuable resources for functional genomics and for exploiting the biotechnological potential of this model diatom species