Low-temperature behaviors of the dipolar magnet Dy3Sb3Zn2O14with a strongly site-mixing disordered kagome lattice

Interesting behaviors may emerge in the magnetic frustrated materials with significant site-mixing disorder. We present the results of the structural, magnetic susceptibility, and specific heat measurements of Dy3Sb3Zn2O14with ∼20%Dy/Zn site-mixing disorder, which results in either a diluted 2D triangular lattice, or an intermediate structure between the kagome and pyrochlore lattice. In addition to the sharp anomaly of the temperature dependence of specific heat atT∼0.35 K, which was attributed to the emergent charge order state for the sample with less disorder, a broad peak atT∼1.5 K, and a small hump belowT∼0.1 K are observed. The measured temperature dependence of specific heat and the Monte Carlo simulation suggest that the magnetic frustration persists despite of a strong site-mixing disorder.

Optimization of Three Extraction Methods and Their Effect on the Structure and Antioxidant Activity of Polysaccharides in Dendrobium huoshanense

Dendrobium huoshanense is a famous edible and medicinal herb, and polysaccharides are the main bioactive component in it. In this study, response surface methodology (RSM) combined with a Box-Behnken design (BBD) was used to optimize the enzyme-assisted extraction (EAE), ultrasound-microwave-assisted extraction (UMAE), and hot water extraction (HWE) conditions and obtain the polysaccharides named DHP-E, DHP-UM, and DHP-H. The effects of different extraction methods on the physicochemical properties, structure characteristics, and bioactivity of polysaccharides were compared. The differential thermogravimetric curves indicated that DHP-E showed a broader temperature range during thermal degradation compared with DHP-UM and DHP-H. The SEM results showed that DHP-E displayed an irregular granular structure, but DHP-UM and DHP-H were sponge-like. The results of absolute molecular weight indicated that polysaccharides with higher molecular weight detected in DHP-H and DHP-UM did not appear in DHP-E due to enzymatic degradation. The monosaccharide composition showed that DHPs were all composed of Man, Glc, and Gal but with different proportions. Finally, the glycosidic bond types, which have a significant effect on bioactivity, were decoded with methylation analysis. The results showed that DHPs contained four glycosidic bond types, including Glcp-(1→, →4)-Manp-(1→, →4)-Glcp-(1→, and →4,6)-Manp-(1→ with different ratios. Furthermore, DHP-E exhibited better DPPH and ABTS radical scavenging activities. These findings could provide scientific foundations for selecting appropriate extraction methods to obtain desired bioactivities for applications in the pharmaceutical and functional food industries.

Distinct Kondo Screening Behaviors in Heavy Fermion Filled Skutterudites with 4f^{1} and 4f^{2} Configurations

CeOs_{4}Sb_{12} (COS) and PrOs_{4}Sb_{12} (POS) are two representative compounds that provide the ideal vantage point to systematically study the physics of multi-f-electron systems. COS with Ce 4f^{1}, and POS with Pr 4f^{2} configurations show distinct properties of Kondo insulating and heavy fermion superconductivity, respectively. We unveiled the underlying microscopic origin by angle-resolved photoemission spectroscopy studies. Their eV-scale band structure matches well, representing the common characters of conduction electrons in ROs_{4}Sb_{12} systems (R=rare earth). However, f electrons interact differently with conduction electrons in COS and POS. Strong hybridization between conduction electrons and f electrons is observed in COS with band dependent hybridization gaps, and the development of a Kondo insulating state is directly revealed. Although the ground state of POS is a singlet, finite but incoherent hybridization exists, which can be explained by the Kondo scattering with the thermally excited triplet crystalline electric field state. Our results help us to understand the intriguing properties in COS and POS, and provide a clean demonstration of the microscopic differences in heavy fermion systems with 4f^{1} and 4f^{2} configurations.

Characterization of an immune deficiency (IMD) homolog from the oriental river prawn, Macrobrachium nipponense

The immune deficiency (IMD) signal pathway mediates innate immunity against Gram-negative bacteria in crustaceans. In the present study, an IMD homolog (MnIMD) from the oriental river prawn, Macrobrachium nipponense was identified. The full-length cDNA of MnIMD was 782bp with an open reading frame of 549 bp that encodes a putative protein of 182 amino acids including a death domain at the C-terminus. Multiple alignment analysis showed that IMDs in prawn M. nipponense and other crustaceans shared high similarity. The recombinant protein of MnIMD was expressed and purified for further functional analyses. Western blot analysis indicated that MnIMD was present in many tissues, but with the highest level in the gills, which was consistent with the qRT-PCR results. After Vibrio parahaemolyticus challenge, MnIMD was significantly induced in gills. RNA interference analysis showed that the IMD pathway was involved in regulating the expression of different antimicrobial peptide (AMP) genes, including Cru4 and Cru6. These results are helpful in promoting research on the innate immunity in M. nipponense.

Changes in the gut microbiome of the Chinese mitten crab (Eriocheir sinensis) in response to White spot syndrome virus (WSSV) infection

Intestinal microorganisms play important roles in maintaining host health, but their functions in aquatic animal hosts have yet to be fully elucidated. The Chinese mitten crab, Eriocheir sinensis, is one such example. We attempted to identify the shift of gut microbiota that occurred in response to infection of white spot syndrome virus (WSSV), an emerging viral pathogen in the crab aquaculture industry. The microbiota may exert some control over aspects of the viral pathogenesis. We investigated the changes in composition and structure of the crab gut microbiome during various WSSV infection stages of 6 h post-infection (hpi) and 48 hpi, using a 16S rRNA approach on the MiSeq Illumina sequencing platform. Four phyla (Firmicutes, Proteobacteria, Tenericutes and Bacteroidetes) were most dominant in the gut of E. sinensis regardless of the WSSV infection stages. However, further analysis revealed that over 12 bacterial phyla, 44 orders and 68 families were significantly different in abundance at various states of WSSV infection. Several intriguing aspects of E. sinensis gut bacteria that had not been previously reported were also uncovered, such as class Mollicutes was dominant here, but absent in crabs from Yangtze River estuary and Chongming Islands. Overall, this study provided the first evidence that changes in gut microbiome were closely associated with the severity of WSSV infection and that indicator taxa could be used to evaluate the crab health status.

Interaction of heat shock protein 60 (HSP60) with microRNA in Chinese mitten crab during Spiroplasma eriocheiris infection

Heat shock protein 60 from the Chinese mitten crab Eriocheir sinensis (EsHSP60) was previously identified in relation to Spiroplasma eriocheiris infection by isobaric tags for relative and absolute quantitation labelling followed by liquid chromatography-tandem mass spectrometry. In the present study, to validate the immune function of this protein, the cDNA of the EsHSP60 gene was cloned. Various crab tissues were assessed using real-time PCR, which showed that EsHSP60 transcription occurred in all tissues examined. The expression profiles of EsHSP60 in haemolymph at transcription and protein levels when infected with S. eriocheiris were investigated by real-time PCR and Western blot analysis, respectively. A significant increase of EsHSP60 transcription and protein expression appeared post-injection in response to S. eriocheiris infection when compared to the control group. The double-luciferase reporter gene assay showed that the microRNA PC-533-3p interacted with the 3'-untranslated region of EsHSP60 and inhibited the translation of EsHSP60. The expression profiles of PC-533-3p during S. eriocheiris infection were also investigated by real-time PCR. However, the change tendency of PC-533-3p was opposite to that of the EsHSP60 after S. eriocheiris challenge. These data indicate that the EsHSP60 proteins may play an important role in mediating the immune responses of E. sinensis to an S. eriocheiris challenge.

Development of In situ hybridization and real-time PCR assays for the detection of Hepatospora eriocheir, a microsporidian pathogen in the Chinese mitten crab Eriocheir sinensis

A microsporidian parasite, Hepatospora eriocheir, is an emerging pathogen for the Chinese mitten crab Eriocheir sinensis. Currently, there is scant information about the way it transmits infection in the crustacean of commercial importance, including its pathogenesis, propagation and infection route in vivo. In this study, chromogenic in situ hybridization (ISH) and quantitative real-time PCR (qPCR) assays were developed to address this pressing need, and we provided an advance in the detection methods available. Pathogens can be seen in situ with associated lesions using ISH. Positive hybridization signals were noted inside the epithelial cells of the hepatopancreas, and putative free parasite spores were observed within the tubule lumen, which were associated with lesions detected by electron microscopy and haematoxylin and eosin (H&E) analysis. qPCR allows the determination of parasite loads in infected tissues, which is important for understanding disease progression and transmission. The hepatopancreas displayed the biggest statistical copy numbers among different tissues of infected crabs, confirming a tissue-specific pathogen infection characteristic. The qPCR assay also proved to be suitable for the diagnosis of asymptomatic carrier crabs. Combination of the two methods could facilitate the study of H. eriocheir infection mechanism in E. sinensis, enhance the early diagnosis of the pathogen and improve the management of microsporidian diseases in commercial crustaceans.

Direct visualization of the novel pathogen, Spiroplasma eriocheiris, in the freshwater crayfish Procambarus clarkii (Girard) using fluorescence in situ hybridization

Spiroplasma eriocheiris is the first spiroplasma strain known to be pathogenic to freshwater crustaceans. It has caused considerable economic losses both in the freshwater crayfish Procambarus clarkii (Girard) and in some other crustaceans. The monitoring of the pathogen in crustacean populations and study of its behaviour in the laboratory require the development of reliable diagnostic tools. In this article, we improved microscopic identification of S. eriocheiris by combining in situ hybridization with specific fluorescently labelled oligonucleotide probes. The established fluorescence in situ hybridization (FISH) allowed simultaneous visualization, identification and localization of S. eriocheiris in the tissues of diseased crayfish P. clarkii and exhibited low background autofluorescence and ideal signal-to-noise ratio. With the advantages of better tissue penetration, potentially more specific and stable, we designed three species-specific oligonucleotide probes utilizing the sequences of 16S-23S rRNA intergenic spacer regions (ISRs) of S. eriocheiris. Positive hybridization signals were visualized in haemocytes and connective tissues of hepatopancreas, cardiac muscle and gill from diseased crayfish. This unique distribution pattern matched the pathological changes when diagnosed by H&E staining and indicated that S. eriocheiris probably spread throughout the tissues in P. clarkii by hemokinesis. This assay will facilitate our understanding of the pathogenesis of S. eriocheiris and enhance the early diagnosis of the novel pathogen.

Studies on characteristics of resistive power calculated with discrete Fourier transform in a pulse-modulated radio frequency discharge

In a pulse-modulated (PM) radio-frequency (RF) capacitively coupled plasma, the DFT (Discrete Fourier Transform)-calculated RF power and the corresponding phase shift between voltage and current measured with calibrated voltage and current probes present oscillations in the pulse rising and falling edges. The oscillating phase shift between voltage and current obtained in the falling edge is outside the expected value for a resistive-capacitive RF discharge. Numerical simulation and analytical analysis are made to interpret these abnormal characteristics and seek an approach to obtaining the reliable resistive (active) RF power. The oscillation is proved to be originated from the oscillating non-zero reactive RF power of the capacitor(s) in the load. At the time instant when the reactive RF power within an integer RF period is not zero, the reactive RF power is mistakenly regarded as the active RF power in the DFT analysis, as a result, the corresponding phase is thus incorrect and even outside the expected value for a resistive-capacitive load. The resistive RF power and the phase can be only correctly calculated at the time instant when the reactive RF power is zero. For a series (or parallel) RC (resistor-capacitor) load and a combined RC load with the dominated series (or parallel) RC impedance, the time instant of the zero reactive RF power is calculated with one of the two proposed empirical formulae. In practice, the DFT-calculated resistive RF power is obtained according to the following procedures: (1) applying DFT to the measured RF voltage and current signals to obtain the power and time instants for minimal phase shifts between voltage and current; (2) selecting the empirical formula to calculate time instants of the zero reactive RF power; (3) getting resistive powers at time instants of the zero reactive RF power. In real PM RF capacitively coupled plasmas, the empirical formula for the series RC load is selected to calculate the resistive RF power. The accuracy of DFT-calculated resistive RF power is proved to be related to two kinds of errors. The first is the error of the time instant of the zero reactive RF power calculated using the empirical formula. This error is relatively lower when the requirement that the dominated parallel or series RC impedance is met and is almost independent of the impedance phase angle of a combined RC load. The second is the error of the DFT-calculated resistive RF power compared with the corresponding time integral RF power at the real zero reactive RF power. This error is independent of the load type or the load impedance but varies with the slope of PM RF voltage amplitude vs. time. The two kinds of errors both increase in the pulse rising and falling edges.

Characterization of two novel ADP ribosylation factors from giant freshwater prawn Macrobrachium rosenbergii and their responses to WSSV challenge

ADP-ribosylation factors (Arfs) are small GTP-binding proteins that have an essential function in intracellular trafficking and organelle structure. To date, little information is available on the Arfs in the economically important giant freshwater prawn Macrobrachium rosenbergii and their relationship to viral infection. Here we identified two Arf genes from M. rosenbergii (MrArf1 and MrArf2) for the first time. Phylogenetic analysis showed that MrArf1, together with MjArf1 from shrimp Marsupenaeus japonicus belonged to Class I Arfs. By contrast, MrArf2 didn't not match any of the Arfs classes of I/II/III, although it could be clustered with an Arf protein from M. japonicas called MjArfn, which may represent an analog of the Arf. MrArf1 was ubiquitously expressed in all the examined tissues, with the highest transcription level in the hepatopancreas, whereas MrArf2 was only highly expressed in the hepatopancreas and exhibited very low levels in the heart, stomach, gills and intestine. The expression level of MrArf1 in the gills was down-regulated post 24 h WSSV challenge, and reached the maximal level at 48 h. MrArf1 in the hepatopancreas went up from 24 to 48 h WSSV challenge. MrArf2 transcript in the gill also went down at 24 h and then was upregulated at 48 h WSSV challenge. MrArf2 increased significantly in the hepatopancreas 24 h after infection and then went down at 48 h WSSV challenge. RNAi results showed that knockdown of MrArf1 or MrArf2 could inhibit the expression of the envelope protein gene vp28 of the WSSV. So, it could be speculated that MrArf1 and MrArf2 might play important roles in the innate immune system against WSSV infection.

Identification and function of two myeloid differentiation factor 88 variants in triangle-shell pearl mussel (Hyriopsis cumingii)

Myeloid differentiation factor 88 (MyD88) is a universal and essential adapter protein that participates in the activation of the Toll-like receptor (TLR)/interleukin-1 receptor-mediated signaling pathway. In this study, two MyD88 genes (HcMyD88-1 and HcMyD88-2) were identified from triangle-shell pearl mussel (Hyriopsis cumingii). Both HcMyD88-1 and HcMyD88-2 proteins were determined to have a death domain at the N-terminal and a TIR domain at the C-terminal. Both HcMyD88-1 and HcMyD88-2 genes were mainly expressed in the hepatopancreas of healthy mussels. HcMyD88-1 and HcMyD88-2 slightly responded to Gram-negative bacterial challenge. Upon bacterial challenge with Gram-positive Staphyloccocus aureus, HcMyD88-1 and HcMyD88-2 transcription levels remarkably increased at 2 and 6h, respectively. Overexpression of HcMyD88-1 and HcMyD88-2 proteins in Drosophila Schneider 2 cells led to the activation of antimicrobial peptide genes. These results indicated that HcMyD88-2 had higher activity than HcMyD88-1 during the activation of attacin A, drosomycin, and metchnikowin genes, suggesting that HcMyD88 genes may play a role in antibacterial innate immune defense.

The resonant radio-frequency magnetic probe tuned by coaxial cable

In this paper, the resonant rf magnetic probe is upgraded by replacing the rotary capacitor in the old version with the series-connected coaxial cable. The numerical calculation and the measurement with the prototype probe show that the rf magnetic probe can achieve resonance at a middle length of the series-connected coaxial cable. The good electrical symmetry of the new rf magnetic probe is ensured by both the identity of series-connected coaxial cables and the new structure of the primary winding. Practical measurements conduced on an rf inductively coupled plasma source demonstrate that performances of the new rf magnetic probe are good.

A tunable radio-frequency magnetic probe

A tunable center-tapped transformer is proposed to increase the output of a rf magnetic probe and improve the signal-to-noise ratio. The tuning is implemented by a variable capacitor connected parallel with the primary winding of the tunable center-tapped transformer. Undesirable common-to-differential conversion is reduced by installing a compensating capacitor. In addition, a planar Faraday shield is installed between the windings of the transformer to further suppress the electrostatic coupling. It is found that tuning the variable capacitor can result in a resonance in the output voltage of the rf magnetic probe. The largest output voltage, achieved with the tunable magnetic probe under the optimal condition, is higher than that with a conventional one by an order of magnitude. Effects of the compensating capacitance on the common-mode output voltage are studied and discussed. Influences of parameters such as cable length, the coupling coefficient, and the step-up ratio of the transformer on the output voltage are also presented. Analytical derivations and numerical calculations based on the equivalent circuit are performed to elucidate the characteristics of the differential mode.

Genomic instability in phenotypically normal regenerants of medicinal plant Codonopsis lanceolata Benth. et Hook. f., as revealed by ISSR and RAPD markers

Codonopsis lanceolata Benth. et Hook. f., commonly known as bonnet bellflower, is a high-valued herb medicine and vegetable. In this study, a large number of plants were regenerated via organogenesis from immature seed-derived calli in C. lanceolata by a simple and efficient method. Compared with the mother donor plant, the regenerated plants did not exhibit visible phenotypic variations in six major morphological traits examined at the stage of one-season-maturity under field conditions. To gain insight into the genomic stability of these regenerated plants, 63 individuals were randomly tagged among a population of more than 2,000 regenerants, and were compared with the single mother donor plant by two molecular markers, the inter-simple sequence repeats (ISSR) and randomly amplified polymorphic DNA (RAPD). Apparent genomic variation was detected in the 63 regenerants, whereas preexisting heterozygosiy in the donor plant was deemed minimal by testing 30 seedlings germinated from selfed seeds of the same donor plant. The percentages of polymorphic bands (PPB) in the ISSR and RAPD analysis were respectively 15.7 and 24.9% for the 63 regenerated plants. Cluster analysis indicates that the genetic similarity values calculated on the basis of RAPD and ISSR data among the 64 plants (63 regenerated and one donor) were respectively 0.894 and 0.933, which allow classification of the plants into distinct groups. Nineteen randomly isolated bands underlying the changed RAPD or ISSR patterns were sequenced, and three of them showed significant homology to known-function genes. Detailed pairwise sequence comparison at one locus between the donor plant and a regenerant revealed that insertion of two short (24 and 19 bp) stretches of nucleotides in the regenerated plant relative to the donor plant occurred in an apparently stochastic manner.