A MYB-related transcription factor from peanut, AhMYB30, improves freezing and salt stress tolerance in transgenic Arabidopsis through both DREB/CBF and ABA-signaling pathways.

Abiotic stresses such as salinity and low temperature have serious impact on peanut growth and yield. The present work investigated the function of a MYB-related transcription factor gene AhMYB30 obtained from peanut under salt and low temperature stresses by transgenic methods. The results indicated that the overexpression of AhMYB30 in Arabidopsis could enhance the resistance of transgenic plants to freezing and salt stresses. The expression of stress-response genes RD29A (Response-to-Dehydration 29A), COR15A (Cold-Regulated 15A), KIN1 (Kinesin 1) and ABI2 (Abscisic acid Insensitive 2) increased in transgenic plants compared with in wild-type. Subcellular localization and transcriptional autoactivation validation demonstrated that AhMYB30 has essential features of transcription factors. Therefore, AhMYB30 may increase salt and freezing stress tolerance as the transcription factor (TF) in Arabidopsis through both DREB/CBF and ABA-signaling pathways. Our results lay the theoretical foundation for exploring stress resistance mechanisms of peanut and offering novel genetic resources for molecular breeding.

First Report of Nigrospora aurantiaca Causing Leaf Blight Disease of Peanut in China.

In June 2021, a previously unreported leaf blight disease of peanut (Arachis hypogaea) was observed on field-grown peanut (Jinhua19) in Laixi city, Shandong province of China. Approximately 5% of plants showed disease symptoms in the fields we investigated. The symptoms first appeared as yellow round or irregular spots on leaves, and then the spots became brown. As the disease progressed, spots became larger and even converge, which later produced leaf chlorosis and abscission. Symptomatic leaves were cut into small pieces, surface disinfested with 70% ethanol for 30s, 1% NaClO for 60s, rinsed three times in sterile water, dried on sterile filter papers, placed on potato dextrose agar (PDA) media, and incubated at 25°C in darkness. Fungal cultures were initially white, with red pigment, then turned gray, and eventually turned black, and aerial hyphae were dense. Conidia were spherical or slightly ellipsoidal, black, smooth, and 8.6 to 11.5 × 8.7 to 14.5µm (n=50). Morphological characteristics of the isolates matched the description of Nigrospora aurantiaca (Wang et al. 2017). Molecular identification was performed by sequencing beta tubulin gene (TUB) with Bt2a/Bt2b and translation elongation factor 1-alpha (TEF) with EF1-728F/EF1-986R (Wang et al. 2021) of a representative isolate ZHX11. TUB (OK489789) and TEF (OK489790) of ZHX11 obtained 100% (401/401 nucleotides) and 99.64% (279/279 nucleotides) similar to those of N. aurantiaca (MN329935, MN264010), respectively. Alignment was conducted separately for each gene set using Clustal W algorithm implemented in MEGA 7.0 (Kumar et al. 2016), and multi-gene (TUB and TEF) phylogenetic analyses using Neighbor-Joining (NJ) method showed that the isolate was N. aurantiaca. To complete Koch's postulates, nine 2-week-old peanut (Zhonghua 12) seedlings were sprayed with conidia suspensions (106 conidia mL-1 in 0.05% Tween 20 buffer). The same number of seedlings were only treated with 0.05% Tween buffer as controls. The experiment was repeated three times. Plants were incubated in a growth chamber (30°C in the day and 25°C at night, a 12-h photoperiod and 80% RH). Ten days after inoculation, typical symptoms were observed on inoculated leaves but not on the controls. N. aurantiaca was reisolated from the diseased leaves but not from the controls. N. sphaerica was observed on peanut in China (Liu et al. 2020). To our knowledge, this is the first report of N. aurantiaca causing leaf blight on peanut in shandong province, China. These findings will help to develop better preventive measures in accordance with the emergence of the new disease.

Neutralizing Antibodies to Human Cytomegalovirus Recombinant Proteins Reduce Infection in an Ex Vivo Model of Developing Human Placentas.

Human cytomegalovirus (HCMV) is the leading viral cause of congenital disease and permanent birth defects worldwide. Although the development of an effective vaccine is a public health priority, no vaccines are approved. Among the major antigenic targets are glycoproteins in the virion envelope, including gB, which facilitates cellular entry, and the pentameric complex (gH/gL/pUL128-131), required for the infection of specialized cell types. In this study, sera from rabbits immunized with the recombinant pentameric complex were tested for their ability to neutralize infection of epithelial cells, fibroblasts, and primary placental cell types. Sera from rhesus macaques immunized with recombinant gB or gB plus pentameric complex were tested for HCMV neutralizing activity on both cultured cells and cell column cytotrophoblasts in first-trimester chorionic villus explants. Sera from rabbits immunized with the pentameric complex potently blocked infection by pathogenic viral strains in amniotic epithelial cells and cytotrophoblasts but were less effective in fibroblasts and trophoblast progenitor cells. Sera from rhesus macaques immunized with the pentameric complex and gB more strongly reduced infection in fibroblasts, epithelial cells, and chorionic villus explants than sera from immunization with gB alone. These results suggest that the pentameric complex and gB together elicit antibodies that could have potential as prophylactic vaccine antigens.

Horizontal Transmission of Cytomegalovirus in a Rhesus Model Despite High-Level, Vaccine-Elicited Neutralizing Antibody and T-Cell Responses.

The development of a vaccine to prevent congenital human cytomegalovirus (HCMV) disease is a public health priority. We tested rhesus CMV (RhCMV) prototypes of HCMV vaccine candidates in a seronegative macaque oral challenge model. Immunogens included a recombinant pentameric complex (PC; gH/gL/pUL128/pUL130/pUL131A), a postfusion gB ectodomain, and a DNA plasmid that encodes pp65-2. Immunization with QS21-adjuvanted PC alone or with the other immunogens elicited neutralizing titers comparable to those elicited by RhCMV infection. Similarly, immunization with all 3 immunogens elicited pp65-specific cytotoxic T-cell responses comparable to those elicited by RhCMV infection. RhCMV readily infected immunized animals and was detected in saliva, blood, and urine after challenge in quantities similar to those in placebo-immunized animals. If HCMV evades vaccine-elicited immunity in humans as RhCMV evaded immunity in macaques, a HCMV vaccine must elicit immunity superior to, or different from, that elicited by the prototype RhCMV vaccine to block horizontal transmission.

Lamprey Immune Protein Mediates Apoptosis of Lung Cancer Cells Via the Endoplasmic Reticulum Stress Signaling Pathway.

Lamprey immune protein (LIP), a novel protein derived from the Lampetra japonica, has been shown to exert efficient tumoricidal actions without concomitant damage to healthy cells. Our study aimed to ascertain the mechanisms by which LIP inhibits lung cancer cells, thus delineating potential innovative therapeutic strategies. LIP expression in lung cancer cells was evaluated by western blotting and immunohistochemistry. Functional assays, such as high-content imaging, 3D-structured illumination microscopy (3D-SIM) imaging, flow cytometry, and confocal laser scanning microscopy, were performed to examine the proliferation and lung cancer cell apoptosis. Tumor xenograft assays were performed using an in vivo imaging system. We observed that LIP induces the decomposition of certain lung cancer cell membranes by destroying organelles such as the microtubules, mitochondria, and endoplasmic reticulum (ER), in addition to causing leakage of cytoplasm, making the maintenance of homeostasis difficult. We also demonstrated that LIP activates the ER stress pathway, which mediates lung cancer cell apoptosis by producing reactive oxygen species (ROS). In addition, injection of LIP significantly retarded the tumor growth rate in nude mice. Taken together, these data revealed a role of LIP in the regulation of lung cancer cell apoptosis via control of the ER stress signaling pathway, thus revealing its possible application in lung cancer treatment.

Prefusion structure of human cytomegalovirus glycoprotein B and structural basis for membrane fusion.

Human cytomegalovirus (HCMV) causes congenital disease with long-term morbidity. HCMV glycoprotein B (gB) transitions irreversibly from a metastable prefusion to a stable postfusion conformation to fuse the viral envelope with a host cell membrane during entry. We stabilized prefusion gB on the virion with a fusion inhibitor and a chemical cross-linker, extracted and purified it, and then determined its structure to 3.6-Å resolution by electron cryomicroscopy. Our results revealed the structural rearrangements that mediate membrane fusion and details of the interactions among the fusion loops, the membrane-proximal region, transmembrane domain, and bound fusion inhibitor that stabilized gB in the prefusion state. The structure rationalizes known gB antigenic sites. By analogy to successful vaccine antigen engineering approaches for other viral pathogens, the high-resolution prefusion gB structure provides a basis to develop stabilized prefusion gB HCMV vaccine antigens.

Interaction Between Halotolerant Phosphate-Solubilizing Bacteria (Providencia rettgeri Strain TPM23) and Rock Phosphate Improves Soil Biochemical Properties and Peanut Growth in Saline Soil.

Soil salinity has adverse effects on soil microbial activity and nutrient cycles and therefore limits crop growth and yield. Amendments with halotolerant phosphate-solubilizing bacteria (PSB) and rock phosphate (RP) may improve properties of saline soil. In this study, we investigated the effects of RP either alone or in combination with PSB (Providencia rettgeri strain TPM23) on peanut growth and soil quality in a saline soil. With the combined application of RP and PSB, plant length and biomass (roots and shoots) and uptake of phosphorus (P), nitrogen (N), and potassium (K) increased significantly. Soil Na+ and Cl- contents decreased in the PR alone or PR combined with PSB treatment groups. There were strongly synergistic effects of RP and PSB on soil quality, including a decrease in pH. The soil available N, P, and K contents were significantly affected by the PSB treatments. In addition, the alkaline phosphomonoesterases, urease, and dehydrogenase activities increased significantly compared with the untreated group; highest alkaline phosphomonoesterases activity was observed in the RP and PSB treatment groups. The composition of rhizosphere soil bacterial communities was determined using 454-pyrosequencing of the 16S rRNA gene. In the PR alone or PR combined with PSB treatment groups, the structure of the soil bacterial community improved with increasing richness and diversity. With PSB inoculation, the relative abundance of Acidobacteria, Chloroflexi, and Planctomycetes increased. The three phyla were also positively correlated with soil available N and root dry weight. These results suggested microbiological mechanisms by which the combined use of RP and PSB improved saline soil and promoted plant growth. Overall, the study indicates the combined use of RP and PSB can be an economical and sustainable strategy to increase plant growth in P-deficient and salt-affected soils.

Pseudomonas laoshanensis sp. nov., isolated from peanut field soil.

A novel Gram-stain-negative, aerobic strain, designated Y22T, was isolated from peanut field soil in Laoshan Mountain in China. Cells of strain Y22T were rod-shaped and motile by a single flagellum. The strain was found to be oxidase- and catalase-positive. 16S rRNA gene sequence based on phylogenetic analysis indicated that strain Y22T belonged to the genus Pseudomonas, and showed the highest 16S rRNA gene sequence similarity of 99.0% to Pseudomonas pelagia JCM 15562T, followed by Pseudomonas salina JCM 19469T (98.4%), Pseudomonas sabulinigri JCM 14963T (97.9%), Pseudomonas bauzanensis CGMCC 1.9095T (97.6%) and Pseudomonas litoralis KCTC23093T (97.5%). The phylogenetic analysis based on multilocus sequence analyses with concatenated 16S rRNA, gyrB, rpoD and rpoB genes indicated that strain Y22T belonged to Pseudomonas pertucinogena lineage. The average nucleotide identity scores between strain Y22T and closely related species were 74.6-82.8%, and the Genome-to-Genome Distance Calculator scores were 16.4-44.9%. The predominant cellular fatty acids of strain Y22T were C18:1ω7c (29.6%), C17:0 cyclo (17.5%) and summed feature 3 (C16:1ω7c and/or C16:1ω6c) (17.4%). The genomic DNA G+C content was 57.9 mol%. On the basis of phenotypic characteristics, phylogenetic analyses and in silico DNA-DNA relatedness, a novel species, Pseudomonas laoshanensis sp. nov. is proposed. The type strain is Y22T (= JCM 32580T = KCTC 62385T = CGMCC 1.16552T).

Genome-wide identification of meiotic recombination hot spots detected by SLAF in peanut (Arachis hypogaea L.).

Recombination hot spots (RHP), caused by meiosis, are considered to play crucial roles in improvement and domestication of crop. Cultivated peanut is one of the most important rich-source of oil and protein crops. However, no direct scale of recombination events and RHP have been estimated for peanut. To examine the scale of recombination events and RHP in peanut, a RIL population with 200 lines and a natural population with 49 cultivars were evaluated. The precise integrated map comprises 4837 SLAF markers with genetic length of 2915.46 cM and density of 1.66 markers per cM in whole genome. An average of 30.0 crossover (2.06 cMMb-1) events was detected per RIL plant. The crossover events (CE) showed uneven distribution among B sub-genome (2.32) and A sub-genome (1.85). There were 4.34% and 7.86% of the genome contained large numbers of CE (> 50 cMMb-1) along chromosomes in F6 and natural population, respectively. High density of CE regions called RHP, showed negative relationship to marker haplotypes conservative region but positive to heatmap of recombination. The genes located within the RHP regions by GO categories showed the responding of environmental stimuli, which suggested that recombination plays a crucial role in peanut adaptation to changing environments.

Long-term continuously monocropped peanut significantly changed the abundance and composition of soil bacterial communities.

Soil sickness is the progressive loss of soil quality due to continuous monocropping. The bacterial populations are critical to sustaining agroecosystems, but their responses to long-term peanut monocropping have not been determined. In this study, based on a previously constructed gradient of continuous monocropped plots, we tracked the detailed feedback responses of soil bacteria to short- and long-term continuous monocropping of four different peanut varieties using high-throughput sequencing techniques. The analyses showed that soil samples from 1- and 2-year monocropped plots were grouped into one class, and samples from the 11- and 12-year plots were grouped into another. Long-term consecutive monocropping could lead to a general loss in bacterial diversity and remarkable changes in bacterial abundance and composition. At the genera level, the dominant genus Bacillus changed in average abundance from 1.49% in short-term monocropping libraries to 2.96% in the long-term libraries. The dominant species Bacillus aryabhattai and Bacillus funiculus and the relatively abundant species Bacillus luciferensis and Bacillus decolorationis all showed increased abundance with long-term monocropping. Additionally, several other taxa at the genus and species level also presented increased abundance with long-term peanut monocropping; however, several taxa showed decreased abundance. Comparing analyses of predicted bacterial community functions showed significant changes at different KEGG pathway levels with long-term peanut monocropping. Combined with our previous study, this study indicated that bacterial communities were obviously influenced by the monocropping period, but less influenced by peanut variety and growth stage. Some bacterial taxa with increased abundance have functions of promoting plant growth or degrading potential soil allelochemicals, and should be closely related with soil remediation and may have potential application to relieve peanut soil sickness. A decrease in diversity and abundance of bacterial communities, especially beneficial communities, and simplification of bacterial community function with long-term peanut monocropping could be the main cause of peanut soil sickness.

Long-term continuously monocropped peanut significantly disturbed the balance of soil fungal communities.

Balancing soil microbial diversity and abundance is critical to sustaining soil health, and understanding the dynamics of soil microbes in a monocropping system can help determine how continuous monocropping practices induce soil sickness mediated by microorganisms. This study used previously constructed gradient continuous monocropping plots and four varieties with different monocropping responses were investigated. The feedback responses of their soil fungal communities to short-term and long-term continuous monocropping were tracked using high-throughput sequencing techniques. The analyses indicated that soil samples from 1 and 2 year monocropped plots were grouped into one class, and samples from the 11 and 12 year plots were grouped into another, regardless of variety. At the species level, the F. solani, Fusarium oxysporum, Neocosmospora striata, Acrophialophora levis, Aspergillus niger, Aspergillus corrugatus, Thielavia hyrcaniae, Emericellopsis minima, and Scedosporium aurantiacum taxa showed significantly increased abundances in the long-term monocropping libraries compared to the short-term cropping libraries. In contrast, Talaromyces flavus, Talaromyces purpureogenus, Mortierella alpina, Paranamyces uniporus, and Volutella citrinella decreased in the long-term monocropping libraries compared to the short-term libraries. This study, combined with our previous study, showed that fungal community structure was significantly affected by the length of the monocropping period, but peanut variety and growth stages were less important. The increase in pathogen abundances and the decrease in beneficial fungi abundances seem to be the main cause for the yield decline and poor growth of long-term monocultured peanut. Simplification of fungal community diversity could also contribute to peanut soil sickness under long-term monocropping. Additionally, the different responses of peanut varieties to monocropping may be related to variations in their microbial community structure.

A novel complement factor I involving in the complement system immune response from Lampetra morii.

Complement factor I (CFI) is a serine protease which plays a key role in the modulation of complement system and the induced-fit factor responsible for controlling the complement-mediated processes. In this study, a CFI gene was cloned and characterized from Lampetra morii (designated as L-CFI) at molecular and cellular levels. The L-CFI protein included a factor I membrane attack complex domain (FIMAC), a scavenger receptor cysteine-rich domain (SRCR), a trypsin-like serine protease domain (Tryp_SPc) and 2 low-density lipoprotein receptor class A domains (LDLa) which would exhibit functional similarities to CFI superfamily proteins. Tissue expression profile analysis showed that L-CFI mRNA constitutively expressed in all tested tissues except erythrocytes, with the predominant expression in liver. The mRNA expression level of L-CFI increased significantly after Vibrio anguillarum and Staphylocccus aureus stimulation. It is demonstrated that L-CFI interacted with L-C3 protein and affected the deposition of L-C3 on the cell surface. Furthermore, lamprey serum after deplete L-CFI and L-C3 reduced the cytotoxic activity against HeLa cells. These findings suggest that L-CFI plays an important role in lamprey immunity and involved in the lamprey complement system.

A novel Miscanthus NAC transcription factor MlNAC10 enhances drought and salinity tolerance in transgenic Arabidopsis.

NAC (NAM, ATAF1/2 and CUC2) proteins are key regulators of various plant stress tolerances. However, knowledge of NAC genes remains largely unknown in Miscanthus. Here, we characterized a novel NAC gene MlNAC10 from M. lutarioriparius than plays a role in abiotic stress tolerance. MlNAC10 encodes a nuclear-localized protein with a C-terminal transactivation domain, and has a specific binding affinity to the NAC recognition sequence (NACRS). Ectopic expression of MlNAC10 in Arabidopsis led to increased sensitivity to abscisic acid (ABA) at early seedling growth stages. In addition, the proline content was significantly increased and the reactive oxygen species (ROS) scavenging capability was significantly enhanced in MlNAC10 overexpression lines under ABA treatment. Moreover, the drought and salt stress tolerance was significantly improved in MlNAC10 overexpression lines. Consistently, the activities of three antioxidant enzymes, namely catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), were dramatically stimulated in the overexpression lines compared to the wild type (WT). Correspondingly, the accumulation of ROS was dramatically decreased and malondialdehyde (MDA) was accumulated at a much lower level in the transgenic lines. Meanwhile, the expression of six abiotic stress-related genes was dramatically stimulated in the overexpression lines in comparison to the WT. Together, our results demonstrated that MlNAC10 acts as an important regulator of drought and salinity stress tolerance by stimulating antioxidant enzymes and alleviating ROS damage via the ABA signaling pathway.

Erratum: Author Correction: Isolation and characterization of halotolerant phosphate-solubilizing microorganisms from saline soils.

[This corrects the article DOI: 10.1007/s13205-018-1485-7.].

Miscanthus NAC transcription factor MlNAC12 positively mediates abiotic stress tolerance in transgenic Arabidopsis.

NAC (NAM, ATAF1/2 and CUC2) transcription factors play critical roles in plant abiotic stress responses. However, knowledge regarding the functional roles of NACs in abiotic stress tolerance and its underlying mechanisms is relatively limited in Miscanthus. In this study, we functionally characterized a novel Miscanthus NAC gene MlNAC12 by ectopic expression in Arabidopsis. MlNAC12 was localized in the nucleus. It could specifically binds to the NAC recognition sequence (NACRS) and has a transactivation activity in the C-terminus. Overexpression of MlNAC12 in Arabidopsis conferred hypersensitivity to exogenous Abscisic acid (ABA) at seed germination and root elongation stages. In addition, MlNAC12 overexpression enhanced germination and root growth under salt (NaCl) stress. Furthermore, MlNAC12 overexpression lines exhibited significantly enhanced drought stress tolerance, which was evidenced by a higher survival rate and a lower water loss rate compared to the wild type (WT). Accordingly, the stomata aperture was remarkably reduced in MlNAC12 overexpression lines in comparison to the WT under drought stress. Furthermore, the accumulation of the reactive oxygen species (ROS) and malondialdehyde (MDA) under abiotic stresses was significantly decreased, accompanied by dramatically enhanced activities of several antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the transgenic plants. Correspondingly, the expression of six stress-responsive genes was significantly up-regulated in MlNAC12 overexpression lines. Together, our results indicate that MlNAC12 is a positive regulator of drought and salt stress tolerance through activating ROS scavenging enzymes.

Isolation and characterization of halotolerant phosphate-solubilizing microorganisms from saline soils.

Halotolerant phosphate-solubilizing microorganisms (PSMs) capable of producing plant-growth-promoting traits were grown on salt medium containing Ca3(PO4)2 or egg yolk. The number of colonies on plates with Ca3(PO4)2 was higher than that on plates with egg yolk. Further, a total of 42 PSM isolates were purified. The majority were Bacillus spp., while one Providencia rettgeri strain was confirmed, for the first time, as a PSM. All PSMs had a phosphate-solubilizing index (PSI) between 1.1 and 2.58 and a strong capacity for dissolving calcium phosphate between 2.25 and 442 mg·L-1. In contrast, these PSMs were less effective when dissolving aluminum phosphate, ferric phosphate and lecithin. Isolates were also tested for growth-promoting substances. The results showed that all isolates were able to secrete indole-3-acetic acid in amounts ranging from 2.7 to 31.8 mg·L-1 and exopolysaccharide within the range 74.3 and 225.7 mg·L-1. Only 12 siderophore-producing strains with siderophore units of 1.9-42.1% were detected. Among them, ten isolates with solubilization rates greater than 200 mg·L-1 and relatively high NaCl tolerance (1.5 M) were classified as candidate PSMs. Eight different organic acids with different contents were detected in the culture filtrates, and propionic and oxalic acids have been proposed as the main mechanisms for solubilization. The ten isolates have the potential for use as bioinoculants to protect plants in saline environments.

Genomic and Transcriptomic Analysis Identified Gene Clusters and Candidate Genes for Oil Content in Peanut (Arachis hypogaea L.).

Peanut (Arachis hypogaea), a major source of vegetable oil in many Asian countries, has become an integral part of human diet globally due to its high nutritional properties and option to consume in different forms. In order to meet the demand of vegetable oil, many peanut breeding programs of China have intensified their efforts in increasing oil content in newly bred varieties for reducing the import of edible oils in China. In this context, transcriptome sequencing data generated on 49 peanut cultivars were analyzed to identify candidate genes and develop molecular markers for seed oil content across multiple environments. Transcriptome analysis identified 5458 differentially expressed genes (DEGs) including 2243 positive DEGs and 3215 negative DEGs involved in oil synthesis process. Genome-wide association study identified 48 significant insertion/deletion (InDel) markers associated with seed oil content across five environments. A comparative genomics and transcriptomics analysis detected a total of 147 common gene clusters located in 17 chromosomes. Interestingly, an InDel cluster associated with seed oil content on A03 chromosome was detected in three different environments. Candidate genes identified on A03 form a haplotype, in which variable alleles were found to be different in oil content in an independent population. This locus is important for understanding the genetic control of peanut oil content and may be useful for marker-assisted selection in peanut breeding programs.

Lamprey immune protein-1 (LIP-1) from Lampetra japonica induces cell cycle arrest and cell death in HeLa cells.

The lamprey (Lampetra japonica), a representative of the jawless vertebrates, is the oldest extant species in the world. LIP-1, which has a jacalin-like domain and an aerolysin pore-forming domain, has previously been identified in Lampetra japonica. However, the structure and function of the LIP-1 protein have not been described. In this study, the LIP-1 gene was overexpressed in HeLa cells and H293T cells. The results showed that the overexpression of LIP-1 in HeLa cells significantly elevated LDH release (P < 0.05), phosphatidylserine exposure and ROS accumulation. The overexpression of LIP-1 also had remarkable effects on the organelles in HeLa cells, while it had no effect on H293T cell organelles. Array data indicated that overexpression of LIP-1 primarily upregulated P53 signaling pathways in HeLa cells. Cell cycle assay results confirmed that LIP-1 caused arrest in the G2/M phase of the cell cycle in HeLa cells. In summary, our findings provide insights into the function and characterization of LIP-1 genes in vertebrates and establish the foundation for further research into the biological function of LIP-1. Our observations suggest that this lamprey protein has the potential for use in new applications in the medical field.

Isolation and functional analysis of fatty acid desaturase genes from peanut (Arachis hypogaea L.).

BACKGROUND: Fatty acid desaturases are enzymes that introduce double bonds into fatty acyl chains. Extensive studies of fatty acid desaturases have been done in many plants. However, less is known about the diversity of this gene family in peanut (Arachis hypogaea L.), an important oilseed crop that is cultivated worldwide. RESULTS: In this study, twelve novel AhFADs genes were identified and isolated from peanut. Quantitative real-time PCR analysis indicated that the transcript abundances of AhFAB2-2 and AhFAD3-1 were higher in seeds than in other tissues examined, whereas the AhADS and AhFAD7-1 transcripts were more abundant in leaves. AhFAB2-3, AhFAD3-2, AhFAD4, AhSLD-4, and AhDES genes were highly expressed in flowers, whereas AhFAD7-2, AhSLD-2, and AhSLD-3 were expressed most strongly in stems. During seed development, the expressions of AhFAB2-2, AhFAD3-1, AhFAD7-1, and AhSLD-3 gradually increased in abundance, reached a maximum expression level, and then decreased. The AhFAB2-3, AhFAD3-2, AhFAD4, AhADS, and AhDES transcript levels remained relatively high at the initial stage of seed development, but decreased thereafter. The AhSLD-4 transcript level remained relatively low at the initial stage of seed development, but showed a dramatic increase in abundance at the final stage. The AhFAD7-2 and AhSLD-2 transcript levels remained relatively high at the initial stage of seed development, but then decreased, and finally increased again. The AhFAD transcripts were differentially expressed following exposure to abiotic stresses or abscisic acid. Moreover, the functions of one AhFAD6 and four AhSLD genes were confirmed by heterologous expression in Synechococcus elongates or Saccharomyces cerevisiae. CONCLUSIONS: The present study provides valuable information that improves understanding of the biological roles of FAD genes in fatty acid synthesis, and will help peanut breeders improve the quality of peanut oil via molecular design breeding.

Diversity and arsenic-tolerance potential of bacterial communities from soil and sediments along a gold tailing contamination gradient.

Gold tailings often release arsenic (As) contaminants into the surrounding environment. Microorganisms play an important role in the As cycle, whereas the effects of As on bacterial communities remain unclear. To reveal the effects of As on the diversity of bacterial communities and their As-tolerance potential, farmland soil and river sediment samples were collected at various distances from tailings in the Dandong area of northeastern China. The bacterial communities were analyzed using high-throughput sequencing of 16S rRNA genes. The membrane transport proteins ArsB and (or) ACR3 pump As(III) out of the cell to resist As toxicity. We studied the abundance and phylogeny of ArsB and ACR3 using PCR-based clone libraries and quantitative PCR. The bacterial community was divided into 10 phyla and 59 genera. The transformation from As(V) to As(III) was predominant, which was coupled with denitrification. Both ArsB and ACR3 likely evolved from different orders of Proteobacteria. The arsB gene seems to be more stable in bestowing bacteria with the capability to respond to the As concentration. Moreover, As with iron, manganese, and total organic carbon also influenced the clustering relationships of samples and bacterial distribution.