Institute of Hydrobiology, Chinese Academy Of Sciences
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Transport of Ciliary Membrane Proteins
No full textCilia and flagella are highly conserved organelles in eukaryotic cells that drive cell movement and act as cell antennae that receive and transmit signals. In addition to receiving and transducing external signals that activate signal cascades, cilia also secrete ciliary ectosomes that send signals to recipient cells, and thereby mediate cell-cell communication. Abnormal ciliary function leads to various ciliopathies, and the precise transport and localization of ciliary membrane proteins are essential for cilium function. This review summarizes current knowledge about the transport processes of ciliary membrane proteins after their synthesis at the endoplasmic reticulum: modification and sorting in the Golgi apparatus, transport through vesicles to the ciliary base, entrance into cilia through the diffusion barrier, and turnover by ectosome secretion. The molecular mechanisms and regulation involved in each step are also discussed. Transport of ciliary membrane proteins is a complex, precise cellular process coordinated among multiple organelles. By systematically analyzing the existing research, we identify topics that should be further investigated to promote progress in this field of research
Influences of litter diversity and soil moisture on soil microbial communities in decomposing mixed litter of alpine steppe species
No full textMany studies have examined the effects of plant diversity and soil water availability on litter decomposition, but little is known about how these two factors interactively influence soil microbial communities, especially in alpine ecosystems. Therefore, the objective of this work was to investigate how litter diversity influences soil microbial communities under different moisture conditions in an alpine steppe ecosystem in Northern Tibet. We collected litter of four abundant plant species (Stipa purpurea, Sp; Carex moorcroftii, Cm; Leontopodium pusillum, Lp; and Artemisia nanschanica, An), and used phospholipid fatty acid (PLFA) analysis to measure soil microbial biomass and community structure. A fully factorial litter mixing experiment under different soil moisture conditions (i.e., 20%, 30% and 40% water holding capacity) was employed. The results showed that litter composition, rather than species richness, significantly affected soil microbial biomass and community composition. The presence of Sp, Cm and An exerted positive or negative effects on soil microbial communities. Litter quality (i.e., C:N ratio) could explain the effects of litter composition on soil microbial communities. High soil moisture facilitated the growth of gram-negative bacteria, while gram-positive bacteria and fungi were more abundant in lower moisture soil. We did not detect any interactive effects of litter species richness and soil moisture on the microbial communities. However, the effects of litter composition on soil microbial communities were dependent on soil moisture condition. These findings indicate that litter composition, rather than species richness, shows interactive effects with soil moisture on soil microbes, and both factors are important in regulating ecosystem functions
Predicting the ecosystem-wide impacts of eradication with limited information using a qualitative modelling approach
No full textConservation-motivated eradications may cause unexpected perverse effects, and these undesirable consequences can be difficult to predict due to the paucity of information on species interactions. A probabilistic qualitative approach, which does not require extensive model parameterization, is becoming increasingly accepted and applied to conservation scenarios when information is limited. However, recent work has criticized this approach on philosophical grounds and proposed an alternative non-probabilistic Boolean analysis method, which circumvents the philosophical difficulties. There is a need for exploring the ability of this novel approach for informing conservation decisions. To do so, we applied the first real-world test of the non-probabilistic Boolean approach using a case study of management of Fells catus (feral cat) and Rattus rattus (black rat) on Christmas Island. We also applied the probabilistic approach as a contrast. Our modeling results showed that the probabilistic approach generated ambiguous outcomes, making it impractical to draw management recommendations. In contrast, the non-probabilistic Boolean approach revealed interpretable rules governing species responses, suggesting that while cat management alone is a risky strategy, the risk of negative effects of cat management on native species can be reduced by the addition of rat management. Thus, given limited resources, in combination with cat management it is prudent to prioritize rat management efforts in the habitats of potentially impacted native species of high concern and value. We conclude that the Boolean approach can be very useful when little information is available to model an ecological system and that it provides a way of identifying the potential risks and benefits of management strategies, enabling better informed conservation decision-making in the face of limited knowledge
Expression of LamB Vaccine Antigen inWolffia globosa(Duck Weed) Against Fish Vibriosis
No full textVibriosis is a commonly found bacterial disease identified among fish and shellfish cultured in saline waters. A multitude ofVibriospecies have been identified as the causative agents. LamB, a member of outer membrane protein (OMPs) family of these bacteria is conserved among allVibriospecies and has been identified as an efficient vaccine candidate against vibriosis. Rootless duckweed (Wolffia) is a tiny, edible aquatic plant possessing characteristics suitable for the utilization as a bioreactor. Thus, we attempted to express a protective edible vaccine antigen against fish vibriosis in nuclear-transformedWolffia. We amplifiedLamBgene from virulentVibrio alginolyticusand it was modified to maximize the protein expression level and translocate the protein to the endoplasmic reticulum (ER) in plants. It was cloned into binary vector pMYC under the control of CaMV 35S promoter and introduced intoWolffia globosabyAgrobacterium-mediated transformation. Integration and expression of theLamBgene was confirmed by genomic PCR and RT-PCR. Western blot analysis revealed accumulation of the LamB protein in 8 transgenic lines. The cross-protective property of transgenicWolffiawas evaluated by orally vaccinating zebrafish through feeding fresh transgenicWolffiaand subsequently challenging with virulentV. alginolyticus. High relative percent survival (RPS) of the vaccinated fish (63.3%) confirmed that fish immunized with transgenicWolffiawere well-protected fromVibrioinfection. These findings suggest thatWolffiaexpressed LamB could serve as an edible plant-based candidate vaccine model for fish vibriosis and feasibility of utilizingWolffiaas bioreactor to produce edible vaccines
Bloom-forming toxic cyanobacterium Microcystis: Quantification and monitoring with a high-frequency echosounder
No full textHarmful cyanobacterial blooms pose a serious environmental threat to freshwater lakes and reservoirs. Investigating the dynamics of toxic bloom-forming cyanobacterial genus Microcystis is a challenging task due to its huge spatiotemporal heterogeneity. The hydroacoustic technology allows for rapid scanning of the water column synoptically and has a significant potential for rapid, non-invasive in situ quantification of aquatic organisms. The aim of this work is to develop a reliable cost-effective method for the accurate quantification of the biomass (B) of gas-bearing cyanobacterium Microcystis in water bodies using a high-frequency scientific echosounder. First, we showed that gas-bearing Microcystis colonies are much stronger backscatterers than gas-free phytoplanktonic algae. Then, in the tank experiments, we found a strong logarithmic relationship between the volume backscattering coefficient (s(v)) and Microcystis B proxies, such as Microcystis-bound chlorophyll a (Chl a(Micro)) and particle volume concentration. The s(v)/B ratio remained unchanged over a wide range of B concentrations when the same source of Microcystis material was used. Our measurements in Lake Dianchi (China) also revealed strong logarithmic relationship between s(v) and Chl a(Micro). The biomass-calibrated echosounder was used to study the diurnal variability of Microcystis B in the lake. We found a sharp increase in the cyanobacterium B and s(v)/Chl a(Micro) ratio near the water surface during the daytime and more uniform distribution of these parameters during the nighttime. We argue that the variations in B and s(v)/Chl a(Micro) ratio could be associated with temporal changes in thermal stratification and turbulent mixing. Our data suggest that the s(v)/Chl a(Micro) ratio positively correlates with (i) the percentage of larger colonies in population and/or (ii) the content of free gas in cells. The last properties allow Microcystis colonies to attain rapid floating, which enables them to concentrate at the water surface at conducive ambient conditions. The s(v)/Chl a(Micro) ratio can be a new important variable reflecting the ability of Microcystis colonies to migrate vertically. Monitoring of this ratio may help to determine the early warning threshold for Microcystis scum formation. The proposed acoustic technology for in situ quantification of Microcystis biomass can be a powerful tool for accurate monitoring and assessment of this cyanobacterium at high spatiotemporal resolution in water bodies. (C) 2020 Elsevier Ltd. All rights reserved
Turning up the heat: warming influences plankton biomass and spring phenology in subtropical waters characterized by extensive fish omnivory
No full textUnderstanding how biological communities respond to climate change is a major challenge in ecology. The response of ectotherms to changes in temperature depends not only on their species-specific thermal tolerances but also on temperature-mediated interactions across different trophic levels. Warming is predicted to reinforce trophic cascades in linear aquatic food chains, but little is known about how warming might affect the lower trophic levels of food webs involving extensive fish omnivory, a common scenario in subtropical and tropical waterbodies. In this study, a mesocosm warming experiment was conducted involving a pelagic food chain (fish-zooplankton-phytoplankton) topped by the omnivorous bighead carp [Aristichthys nobilis(Richardson)]. We found that temperature elevation significantly enhanced the growth of fish and suppressed zooplankton, including both metazooplankton and ciliates, while abundances of phytoplankton, despite disruption of temporal dynamics, did not increase correspondingly-likely due to fish predation. Our results suggest that trophic cascades are less unlikely to be reinforced by warming in food chains involving significant omnivory. Moreover, we found that warming advanced the spring abundance peak of phytoplankton abundance and that of the parthenogenetic rotiferBrachionus quadridentatus; whereas, it had no effect on the only sexually reproducing copepod,Mesocyclops leuckarti, presumably due to its prolonged life history. Our study also confirmed that warming may lead to a phenological mismatch between some predators and their prey because of the distinct life histories among taxa, with potentially severe consequences for resource flow in the food chain, at least in the short term
Zebrafish F-box Protein fbxo3 Negatively Regulates Antiviral Response through Promoting K27-Linked Polyubiquitination of the Transcription Factors irf3 and irf7
No full textFBXO3, belongs to the F-box family of proteins, which has been reported to involve in host autoimmune and inflammatory responses by promoting its substrates for ubiquitylation. However, thus far, its physiological function in antiviral immunity remains elusive. In this study, we report that overexpression of zebrafish fbxo3 suppresses cellular antiviral responses. Moreover, disruption of fbxo3 in zebrafish increases the survival rate upon spring viremia of carp virus exposure. Further assays indicate that fbxo3 interacts with irf3/irf7 and specifically catalyzes K27-linked ubiquitination of irf3 and irf7, resulting in proteasomal degradation of irf3 and irf7. However, the F-box domain of fbxo3 is not required for fbxo3 to interact with irf3/irf7 and to inhibit transactivity of irf3 and irf7. This study provides novel insights into fbxo3 function and the underlying mechanisms. In addition, it sheds new light on the regulation of IFN-I signaling by F-box proteins
Mediation of Mucosal Immunoglobulins in Buccal Cavity of Teleost in Antibacterial Immunity
No full textThe buccal mucosa (BM) of vertebrates is a critical mucosal barrier constantly exposed to rich and diverse pathogens from air, water, and food. While mammals are known to contain a mucosal associated lymphoid tissue (MALT) in the buccal cavity which induces B-cells and immunoglobulins (Igs) responses against bacterial pathogens, however, very little is known about the evolutionary roles of buccal MALT in immune defense. Here we developed a bath infection model that rainbow trout experimentally exposed toFlavobacterium columnare(F. columnare), which is well known as a mucosal pathogen. Using this model, we provided the first evidence for the process of bacterial invasion in the fish BM. Moreover, strong pathogen-specific IgT responses and accumulation of IgT(+)B-cells were induced in the buccal mucus and BM of infected trout withF. columnare. In contrast, specific IgM responses were for the most part detected in the fish serum. More specifically, we showed that the local proliferation of IgT(+)B-cells and production of pathogen-specific IgT within the BM upon bacterial infection. Overall, our findings represent the first demonstration that IgT is the main Ig isotype specialized for buccal immune responses against bacterial infection in a non-tetrapod species
Mediation of Mucosal Immunoglobulins in Buccal Cavity of Teleost in Antibacterial Immunity
No full textThe buccal mucosa (BM) of vertebrates is a critical mucosal barrier constantly exposed to rich and diverse pathogens from air, water, and food. While mammals are known to contain a mucosal associated lymphoid tissue (MALT) in the buccal cavity which induces B-cells and immunoglobulins (Igs) responses against bacterial pathogens, however, very little is known about the evolutionary roles of buccal MALT in immune defense. Here we developed a bath infection model that rainbow trout experimentally exposed toFlavobacterium columnare(F. columnare), which is well known as a mucosal pathogen. Using this model, we provided the first evidence for the process of bacterial invasion in the fish BM. Moreover, strong pathogen-specific IgT responses and accumulation of IgT(+)B-cells were induced in the buccal mucus and BM of infected trout withF. columnare. In contrast, specific IgM responses were for the most part detected in the fish serum. More specifically, we showed that the local proliferation of IgT(+)B-cells and production of pathogen-specific IgT within the BM upon bacterial infection. Overall, our findings represent the first demonstration that IgT is the main Ig isotype specialized for buccal immune responses against bacterial infection in a non-tetrapod species
Automated accelerated solvent extraction method for total lipid analysis of microalgae
No full textFor algae-based biofuel researches, it is usually necessary to extract and quantitatively measure total lipids. The most popular total lipid determination methods for tissues are solvent-based methods with either manual or Soxhlet extraction. Although some investigators have modified these traditional methods, the modifications have rarely been specified in detail, nor has their effectiveness been critically evaluated on microalgae biomass. As a result, there are often significant differences in the analyses of total lipid contents among investigators and laboratories. To assess the effectiveness of different total lipid extraction protocols for microalgae, several conventional lipid extraction methods were systematically compared with an accelerated solvent extraction (ASE) method. Optimal conditions for the ASE method were determined to be three cycles of 3 min at 125 degrees C using a 5 ml extraction cell containing 20 to 150 mg of dry algal biomass. Critical comparisons and assessments of these total lipid extraction methods from microalgae were performed for both total lipid extraction efficiency and extracted lipid quality (lipid decomposition and oxidation). Results obtained from five algal species indicated that hot Soxhlet extraction and ASE were comparable in total lipid extraction efficiencies, which were higher than the efficiencies obtained from conventional manual extraction methods. However, lipid oxidation resulting from different extraction methods indicated that continuous heating with a hot Soxhlet extraction method could lead to lipid oxidation. Considering the efficiency and quality of the extracted lipids, extraction time, extraction steps and consumed solvent volumes, ASE is a very promising method for total lipid extraction and analysis of lipids from microalgal biomass