Intra-specific comparison of mitochondrial genomes reveals host gene fragment exchange via intron mobility in Tremella fuciformis.

BACKGROUND: Mitochondrial genomic sequences are known to be variable. Comparative analyses of mitochondrial genomes can reveal the nature and extent of their variation. RESULTS: Draft mitochondrial genomes of 16 Tremella fuciformis isolates (TF01-TF16) were assembled from Illumina and PacBio sequencing data. Mitochondrial DNA contigs were extracted and assembled into complete circular molecules, ranging from 35,104 bp to 49,044 bp in size. All mtDNAs contained the same set of 41 conserved genes with identical gene order. Comparative analyses revealed that introns and intergenic regions were variable, whereas genic regions (including coding sequences, tRNA, and rRNA genes) were conserved. Among 24 introns detected, 11 were in protein-coding genes, 3 in tRNA genes, and the other 10 in rRNA genes. In addition, two mobile fragments were found in intergenic regions. Interestingly, six introns containing N-terminal duplication of the host genes were found in five conserved protein-coding gene sequences. Comparison of genes with and without these introns gave rise to the following proposed model: gene fragment exchange with other species can occur via gain or loss of introns with N-terminal duplication of the host genes. CONCLUSIONS: Our findings suggest a novel mechanism of fungal mitochondrial gene evolution: partial foreign gene replacement though intron mobility.

The complete chloroplast genome of the green algae Hariotina reticulata (Scenedesmaceae, Sphaeropleales, Chlorophyta).

In this study, the chloroplast genome of Hariotina reticulata was fully sequenced and compared to other Sphaeropleales chloroplast genomes. It is 210,757 bp larger than most Sphaeropleales cpDNAs. It presents a traditional chloroplast structure, and contains 103 genes, including 68 protein-coding genes, six rRNA genes and 29 tRNA genes. The coding region constitutes of 43% of the whole cpDNA. Eighteen introns are found in 11 genes and six introns are unique for Hariotina. 11 open reading frames are identified among these introns. The synteny between Hariotina and Acutodesmus cpDNAs is in general identical, while within Sphaeropleales order, high variability in cpDNA architecture is indicated by general high DCJ distances. Ankyra judayi exhibits the greatest dissimilarity in gene synteny to the others and share some unique gene clusters with Treubaria triappendiculata. The phylogenomic analyses show that A. judayi is clustered with Treubariaceae species and sister to Chlorophyceae incertae sedis and other Sphaeropleales species. The monophyly of Sphaeropleales is rejected.

mcp, aer, cheB, and cheV contribute to the regulation of Vibrio alginolyticus (ND-01) adhesion under gradients of environmental factors.

Adhesion is a key virulence factor of pathogens and can be affected by the environment. Our previously research with RNA-seq indicated that mcp, aer, cheB, and cheV might play roles in the regulation of adhesion in Vibrio alginolyticus (ND-01). In order to determine whether and how environmental factors affect adhesion through these genes, gene silencing was performed followed by quantitative real-time PCR (qRT-PCR), RNAi, transmission electron microscopy, and adhesion, capillary, and motility assays to verify how these genes influence adhesion. Silencing these genes led to deficiencies in adhesion, chemotaxis, flagellar assembly, and motility. The expression levels of cheA, cheW, and cheY, which are important genes closely related to the functions of mcp, aer, cheV, and cheB, were significantly downregulated in all of the RNAi groups. The expression of mcp, aer, cheV, and cheB under different gradients of temperature, pH, and salinity and after starvation for various durations was also detected, which showed that these genes were sensitive to certain environmental stresses, particularly pH and starvation. Our results indicated that mcp, aer, cheB, and cheV: (1) are necessary for ND-01 adhesion; (2) play key roles in the bacterial chemotaxis pathway by controlling the expression of downstream genes; (3) might affect adhesion by impacting motility, though motility is not the only route through which adhesion is affected; and (4) contribute to the regulation of ND-01 adhesion in natural environments with different temperatures, pH levels, and salinities as well as after various starvation periods.

Celastrol-Induced Nur77 Interaction with TRAF2 Alleviates Inflammation by Promoting Mitochondrial Ubiquitination and Autophagy.

Mitochondria play an integral role in cell death, autophagy, immunity, and inflammation. We previously showed that Nur77, an orphan nuclear receptor, induces apoptosis by targeting mitochondria. Here, we report that celastrol, a potent anti-inflammatory pentacyclic triterpene, binds Nur77 to inhibit inflammation and induce autophagy in a Nur77-dependent manner. Celastrol promotes Nur77 translocation from the nucleus to mitochondria, where it interacts with tumor necrosis factor receptor-associated factor 2 (TRAF2), a scaffold protein and E3 ubiquitin ligase important for inflammatory signaling. The interaction is mediated by an LxxLL motif in TRAF2 and results not only in the inhibition of TRAF2 ubiquitination but also in Lys63-linked Nur77 ubiquitination. Under inflammatory conditions, ubiquitinated Nur77 resides at mitochondria, rendering them sensitive to autophagy, an event involving Nur77 interaction with p62/SQSTM1. Together, our results identify Nur77 as a critical intracellular target for celastrol and unravel a mechanism of Nur77-dependent clearance of inflamed mitochondria to alleviate inflammation.

Diversity of Bacillus-like bacterial community in the sediments of the Bamenwan mangrove wetland in Hainan, China.

Members of the genus Bacillus and related spore-forming genera are ubiquitous. However, Bacillus-like species isolated from marine sediments have attracted less interest than their terrestrial relatives. Here, we investigated the diversity of Bacillus-like bacterial communities in the sediments of the Bamenwan mangrove wetland in Hainan, China, using culture-dependent and culture-independent methods, and present the first report on this subject. We also discovered some potential novel species from the sediment samples. Four families, Bacillaceae (58%), Paenibacillaceae (22%), Alicyclobacillaceae (15%), and Planococcaceae (5%), and 9 genera, Bacillus (42%), Paenibacillus (16%), Halobacillus (13%), Alicyclobacillus (11%), Rummeliibacillus (5%), Cohnella (5%), Tumebacillus (4%), Pontibacillus (3%), and Aneurinibacillus (2%), were identified by pyrosequencing. In contrast, only 4 genera, Bacillus (57%), Paenibacillus (23%), Halobacillus (14%), and Virgibacillus (6%), were detected by the culture-dependent method. In the 16S rDNA sequencing analysis, the isolates HB12036 and HB12037 were closest to Bacillus okuhidensis Kh10-101T and Paenibacillus xylanilyticus XIL14T with similarities of 94.8% and 95.9%, respectively, indicating that these were novel species. Bacillus sp. HB12035 and HB12040 exhibited antimicrobial activity against Staphylococcus aureus ATCC 25923, and Bacillus sp. HB12033 exhibited antimicrobial activity against Ustilago scitaminea Syd.

Bacterial microbiota profile in gills of modified atmosphere-packaged oysters stored at 4 °C.

As filter-feeding bivalves, oysters can accumulate microorganisms into their gills, causing spoilage and potential safety issues. This study aims to investigate the changes in the gill microbiota of oysters packed under air and modified atmospheres (MAs, 50% CO2: 50% N2, 70% CO2: 30% O2, and 50% CO2: 50% O2) during storage at 4 °C. The diversity of bacterial microbiota in oyster gills was profiled through polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis on the 16S rRNA gene V3 region to describe the variation during the entire storage period. The DGGE profile revealed high bacterial diversity in the air- and MA-packaged oyster gills, and the spoilage bacterial microbiota varied in the MA-packaged oyster gills. Results indicated that CO2:O2 (70%:30%) was suitable for oyster MA packaging and that high bacterial loads in oyster gills need to be considered during storage. In addition, Lactobacillus and Lactococcus species were found to grow dominantly in fresh oyster gills under MA packaging, which supports the potential application of MA packaging for oyster storage.

Analysis of the Mitochondrial Genome in Hypomyces aurantius Reveals a Novel Twintron Complex in Fungi.

Hypomyces aurantius is a mycoparasite that causes cobweb disease, a most serious disease of cultivated mushrooms. Intra-species identification is vital for disease control, however the lack of genomic data makes development of molecular markers challenging. Small size, high copy number, and high mutation rate of fungal mitochondrial genome makes it a good candidate for intra and inter species differentiation. In this study, the mitochondrial genome of H. H.a0001 was determined from genomic DNA using Illumina sequencing. The roughly 72 kb genome shows all major features found in other Hypocreales: 14 common protein genes, large and small subunit rRNAs genes and 27 tRNAs genes. Gene arrangement comparison showed conserved gene orders in Hypocreales mitochondria are relatively conserved, with the exception of Acremonium chrysogenum and Acremonium implicatum. Mitochondrial genome comparison also revealed that intron length primarily contributes to mitogenome size variation. Seventeen introns were detected in six conserved genes: five in cox1, four in rnl, three in cob, two each in atp6 and cox3, and one in cox2. Four introns were found to contain two introns or open reading frames: cox3-i2 is a twintron containing two group IA type introns; cox2-i1 is a group IB intron encoding two homing endonucleases; and cox1-i4 and cox1-i3 both contain two open reading frame (ORFs). Analyses combining secondary intronic structures, insertion sites, and similarities of homing endonuclease genes reveal two group IA introns arranged side by side within cox3-i2. Mitochondrial data for H. aurantius provides the basis for further studies relating to population genetics and species identification.

The effect of polar auxin transport on adventitious branches formation in Gracilaria lichenoides in vitro.

Seaweed tissue culture (STC) is an important micropropagation tool that has been applied for strain improvement, micropropagation and genetic engineering. Because the mechanisms associated with STC are poorly understood, its application to these organisms lags far behind that of tissue culture propagation of higher plants. Auxin, calcium (Ca2+ ) and hydrogen peroxide (H2 O2 ) fluxes all play key roles during plant growth and development. In this study, we therefore measured indole-3-acetic acid, Ca2+ and H2 O2 fluxes of Gracilaria lichenoides explants during adventitious branches (ABs) formation for the first time using noninvasive micro-test technology. We confirmed that polar auxin transport (PAT) also occurs in the marine red alga G. lichenoides. We additionally found that N-1-naphthylphthalamic acid may suppress auxin efflux via ABCB1 transporters and then inhibit ABs formation from the apical region of G. lichenoides segments. The involvement of Ca2+ and H2 O2 fluxes in PAT-mediated AB formation in G. lichenoides was also investigated. We propose that complex feedback among Ca2+ , H2 O2 and auxin signaling and response systems may occur during ABs polar formation in G. lichenoides explants, similar to that in higher plants. Our results provide innovative insights that should aid future elucidation of mechanisms operative during STC.

Simultaneous Quantitation of Free Amino Acids, Nucleosides and Nucleobases in Sipunculus nudus by Ultra-High Performance Liquid Chromatography with Triple Quadrupole Mass Spectrometry.

To evaluate the nutritional and functional value of Sipunculus nudus, a rapid, simple and sensitive analytical method was developed using ultra-high performance liquid chromatography coupled with a triple quadrupole mass detection in multiple-reaction monitoring mode for the simultaneous quantitative determination of 25 free amino acids and 16 nucleosides and nucleobases in S. nudus within 20 min, which was confirmed to be reproducible and accurate. The limits of detection (LODs) and quantification (LOQs) were between 0.003-0.229 µg/mL and 0.008-0.763 µg/mL for the 41 analytes, respectively. The established method was applied to analyze 19 batches of S. nudus samples from four habitats with two different processing methods. The results showed that S. nudus contained a variety of free amino acids, nucleosides and nucleobases in sufficient quantity and reasonable proportion. They also demonstrated that the contents of these compounds in different parts of S. nudus were significantly discriminating, which were in the order: (highest) coelomic fluid > body wall > intestine (lowest). The method is simple and accurate, and could serve as a technical support for establishing quality control of S. nudus and other functional seafoods. Moreover, the research results also laid foundation for further exploitation and development of S. nudus.

De Novo Assembly and Characterization of Early Embryonic Transcriptome of the Horseshoe Crab Tachypleus tridentatus.

The horseshoe crab Tachypleus tridentatus is a unique marine species and a potential model for marine invertebrate. Limited genomic and transcriptional data are currently available to understand the molecular mechanisms underlying the embryonic development of T. tridentatus. Here, we reported for the first time the de novo transcriptome assembly for T. tridentatus at embryonic developmental stage using Illumina RNA-seq platform. Approximate 38 million reads were obtained and further assembled into 133,212 unigenes. Sequence homology analysis against public databases revealed that 33,796 unigenes could be annotated with gene descriptions. Of the annotated unigenes, we identified a number of key components of several conserved metazoan signaling pathways (Hedgehog, Wnt, TGF-beta and Notch pathways) and other important regulatory genes involved in embryonic development. Targeted searching of Pax family genes which play critical roles in the formation of tissue and organ during embryonic development identified a complete set of Pax family genes. Moreover, the full length T. tridentatus Pax1/9a (TtPax1/9a) and Pax1/9b (TtPax1/9b) cDNA sequences were determined based on the transcriptome, demonstrating the immediate application of our database. Using quantitative real time PCR, we analyzed the expression patterns of TtPax1/9a and TtPax1/9b in different tissues of horseshoe crab. Taking advantage of Drosophila model, we further found that TtPax1/9b, but not TtPax1/9a, can partly rescue the Drosophila homolog Poxm dysfunction-caused lethality at the larval stage. Our study provides the embryonic transcriptome of T. tridentatus which could be immediately used for gene discovery and characterization, functional genomics studies in T. tridentatus. This transcriptome database will also facilitate the investigations of molecular mechanisms underlying embryonic development of T. tridentatus and other marine arthropods as well.

De-novo assembly and characterization of Chlorella minutissima UTEX2341 transcriptome by paired-end sequencing and the identification of genes related to the biosynthesis of lipids for biodiesel.

Chlorella minutissima is considered to be one of the promising feedstocks for biofuels in the future. In this study, the transcriptome from the oil-rich strain UTEX2341 of C. minutissima was generated based on Illumina paired-end sequencing. Through de-novo assembly, a total of 14,905 isogenes were obtained and compacted into 6216 unigenes. A total of 80% of the unigenes were assigned with GO terms and were further subdivided into 55 sub-categories. KEGG analysis demonstrated that 37.2% of the unigenes could be accessed and mapped into 278 pathways. Interestingly, the genes that encoded key enzymes that are involved in the biosynthesis, elongation, and metabolism of fatty acids were identified, including malonyl-CoA-ACP transacylase, 3-ketoacyl-ACP synthase, 3-ketoacyl-ACP reductase, and others. Moreover, the genes that are involved in triacylglycerol (TAG) biosynthesis and metabolism were also observed. Therefore, the transcriptome analysis of C. minutissima UTEX2341 not only supplies comprehensive insight into the molecular pathway that is involved in the biosynthesis of biofuel precursors but also provides substantial valuable genomic resources to accelerate the further development and utilization of biofuels.

The complete mitochondrial DNA sequence of the green algae Hariotina sp. F30 (Scenedesmaceae, Sphaeropleales, Chlorophyceae).

The complete mitochondrial genome of the green algae Hariotina sp. F30 was obtained in this study using Illumina sequencing data. It is 51 915 bp in length with 36.23% GC content. The genome contains 13 protein-coding genes, 23 tRNA genes and six rRNA genes, all of which are encoded on the heavy strand. AUG is a universal initiation codon among 13 protein-coding genes. UCA is a universal termination codon for most protein-coding gens except UAA in cox1 and cob genes and UGA in nad6 gene. CUU anticodon for tRNA-Lys was detected for the first time in Sphaeropleales.

Complete mitochondrial genome of a DHA-rich protist Schizochytrium sp. TIO1101.

Schizochytrium sp. TIO1101 is a crucial commercial alga used to produce docosahexaenoic acid (DHA), a long-chain polyunsaturated fatty acid that is beneficial for human health. In this study, we sequenced the mitochondrial genome (mitogenome) of Schizochytrium sp. TIO1101 for the first time using an Illumina HiSeq 2500 system (Illumina Inc., San Deigo, CA). The assembled mitogenome was 31 494 bp long with 33.92% GC content. The mitogenome contains 56 genes, including 33 protein-coding genes, 21 transfer RNA genes and two ribosomal RNA genes. Maximum-likelihood phylogenetic analysis of Schizochytrium sp. TIO1101 showed that it was most closely related to Thraustochytrium aureum among the examined species.

Transcriptome analysis identifies genes involved in adventitious branches formation of Gracilaria lichenoides in vitro.

Tissue culture could solve the problems associated with Gracilaria cultivation, including the consistent supply of high-quality seed stock, strain improvement, and efficient mass culture of high-yielding commercial strains. However, STC lags behind that of higher plants because of the paucity of genomic information. Transcriptome analysis and the identification of potential unigenes involved in the formation and regeneration of callus or direct induction of ABs are essential. Herein, the CK, EWAB and NPA G. lichenoides transcriptomes were analyzed using the Illumina sequencing platform in first time. A total of 17,922,453,300 nucleotide clean bases were generated and assembled into 21,294 unigenes, providing a total gene space of 400,912,038 nucleotides with an average length of 1,883 and N 50 of 5,055 nucleotides and a G + C content of 52.02%. BLAST analysis resulted in the assignment of 13,724 (97.5%), 3,740 (26.6%), 9,934 (70.6%), 10,611 (75.4%), 9,490 (67.4%), and 7,773 (55.2%) unigenes were annotated to the NR, NT, Swiss-Prot, KEGG, COG, and GO databases, respectively, and the total of annotated unigenes was 14,070. A total of 17,099 transcripts were predicted to possess open reading frames, including 3,238 predicted and 13,861 blasted based on protein databases. In addition, 3,287 SSRs were detected in G.lichenoides, providing further support for genetic variation and marker-assisted selection in the future. Our results suggest that auxin polar transport, auxin signal transduction, crosstalk with other endogenous plant hormones and antioxidant systems, play important roles for ABs formation in G. lichenoides explants in vitro. The present findings will facilitate further studies on gene discovery and on the molecular mechanisms underlying the tissue culture of seaweed.

Pseudonocardia nematodicida sp. nov., isolated from mangrove sediment in Hainan, China.

Two aerobic, Gram-stain positive actinobacterial strains with nematicidal activity, designated HA11164(T) and HA12591, were isolated from mangrove sediments in Hainan, China. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strains HA11164(T) and HA12591 belong to the genus Pseudonocardia and are closely related to Pseudonocardia carboxydivorans (with the similarities of 98.30 and 98.24 %, respectively), Pseudonocardia alni (98.23 and 98.16 %, respectively) and Pseudonocardia antimicrobica (98.10 and 98.03 %, respectively). The major polar lipids of the strain HA11164(T), as a representative strain of the two strains, were found to consist of phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, five unidentified glycolipids and four unidentified polar lipids. The predominant menaquinone of strain HA11164(T) was identified as MK-8 (H4), and the major fatty acids were identified as iso-C16:0, C17:1 ω10, C16:0 and C16:1 ω9. The G+C content of strain HA11164(T) was determined to be 74.9 mol%. The DNA-DNA relatedness values between strains HA11164(T) and P. alni, Pseudonocardia tropica, Pseudonocardia antarctica, P. carboxydivorans and Pseudonocardia parietis were 58.3, 56.2, 50.0, 57.1 and 46.0 %, respectively. Based on the results of this polyphasic study, strains HA11164(T) and HA12591 are considered to represent a novel species of the genus Pseudonocardia, for which the name Pseudonocardia nematodicida sp. nov. is proposed. The type strain is HA11164(T) (=CGMCC 4.7118(T) = DSM 45940(T)).

Arginine methylation of HSP70 regulates retinoid acid-mediated RARß2 gene activation.

Although "histone" methyltransferases and demethylases are well established to regulate transcriptional programs and to use nonhistone proteins as substrates, their possible roles in regulation of heat-shock proteins in the nucleus have not been investigated. Here, we report that a highly conserved arginine residue, R469, in HSP70 (heat-shock protein of 70 kDa) proteins, an evolutionarily conserved protein family of ATP-dependent molecular chaperone, was monomethylated (me1), at least partially, by coactivator-associated arginine methyltransferase 1/protein arginine methyltransferase 4 (CARM1/PRMT4) and demethylated by jumonji-domain-containing 6 (JMJD6), both in vitro and in cultured cells. Functional studies revealed that HSP70 could directly regulate retinoid acid (RA)-induced retinoid acid receptor ß2 (RARß2) gene transcription through its binding to chromatin, with R469me1 being essential in this process. HSP70's function in gene transcriptional regulation appears to be distinct from its protein chaperon activity. R469me1 was shown to mediate the interaction between HSP70 and TFIIH, which involves in RNA polymerase II phosphorylation and thus transcriptional initiation. Our findings expand the repertoire of nonhistone substrates targeted by PRMT4 and JMJD6, and reveal a new function of HSP70 proteins in gene transcription at the chromatin level aside from its classic role in protein folding and quality control.

Nocardiopsis mangrovei sp. nov., isolated from mangrove sediment.

Two Gram-positive actinobacterial strains, designated HA11166(T) and HA12420, were isolated from mangrove sediments in Hainan, China. The bacterial cells grew with 0-9 % (w/v) NaCl, at 15-40 °C and pH 5.0-10.0, with the optimum growth at 1 % NaCl, 30-37 °C and pH 7.0. The organisms had a range of chemical and morphological properties consistent with their classification in the genus Nocardiopsis. Phylogenetic analysis of the 16S rRNA gene sequences indicated that strains HA11166(T) and HA12420 can be affiliated to the genus Nocardiopsis and most closely related to Nocardiopsis trehalosi VKM Ac-942(T) (with the similarity of 97.2 and 97.5 %, respectively). The value of DNA-DNA relatedness between type strain HA11166(T), selected as the representative strain, and N. trehalosi VKM Ac-942(T) was 38.8 %. The DNA G+C content of strain HA11166(T) was 73.7 %. On the basis of these phenotypic and genotypic data, strains HA11166(T) and HA12420 are proposed to represent a novel species of the genus Nocardiopsis, for which the name Nocardiopsis mangrovei sp. nov. is proposed. The type strain is HA11166(T) (=CGMCC 4.7119(T)=DSM 46665(T)).

Antipyretic and anti-inflammatory activities of Thais luteostoma extracts and underlying mechanisms.

Thais luteostoma has been utilized as a crude drug whose shell and soft tissue have been widely used for the treatment of heat syndrome in China for thousands of years. The present study was designed to investigate the antipyretic and anti-inflammatory activities of T. luteostoma. T. luteostoma was divided into shell (TLSH) and soft tissue (TLST) samples in the present study. The rat model of yeast-induced fever was used to investigate their antipyretic effects; and the rat model of hind paw edema induced by carrageenan was utilized to study their anti-inflammatory activities, and at the same time, the concentration variations of the central neurotransmitter [prostaglandin E2 (PGE2) and cyclic adenosine monophosphate (cAMP)], inflammatory mediators [tumor necrosis factor (TNFα), interleukin-1ß (IL-1), interleukin-2 (IL-2) and interleukin-6 (IL-6)] and ion (Na(+) and Ca(2+)) were also tested. The results showed that TLSH and TLST extracts significantly inhibited yeast-induced pyrexia in rats (P < 0.05), and exhibited more lasting effects as compared to aspirin, and TLSH had the better antipyretic activity than TLST, and that TLSH and TLST could significantly prevent against carrageenan induced paw edema in rats (P < 0.05); and markedly reduced levels of PGE2, cAMP, TNFα, IL-1ß, IL-2, IL-6, and Na(+)/Ca(2+). In fever model, TLST could significantly reduce the levels of PGE2 (P < 0.01) in rats' homogenate and TNFα (P < 0.05), IL-1ß (P < 0.01) in the plasma than TLSH, whereas TLSH could reduce the content of IL-2 (P < 0.01) and IL-6 (P < 0.01) in plasma and increase the content of Ca(2+) (P < 0.01) in plasma and homogenate more significantly than TLST. In conclusion, T. luteostoma extract has antipyretic and anti-inflammatory activities, which may be mediated through the suppression of production of PGE2, cAMP, Na(+)/Ca(2+), TNFα, IL-1ß, IL-2, and IL-6.

Cloning and functional analysis of putative malonyl-CoA:acyl-carrier protein transacylase gene from the docosahexaenoic acid-producer Schizochytrium sp. TIO1101.

Malonyl-CoA:acyl-carrier protein transacylase (MCAT), which transfers the malonyl group from malonyl-CoA to holo-acyl carrier protein (ACP), is a key enzyme in fatty acid biosynthesis. Schizochytrium sp. TIO1101 is a marine protist with high levels of docosahexaenoic acid accumulation. In this study, the putative fabD gene coding MCAT was isolated from Schizochytrium sp. TIO1101. The Schizochytrium MCAT gene (ScTIOfabD) contained an 1176 bp open reading frame encoding a protein of 391 amino acids. The ScTIOfabD gene exhibited high novelty in nucleotide and amino acid sequence. The highest amino acid identity was only 35 % between ScTIOMCAT and the reported MCATs. Further studies demonstrated that ScTIOMCAT could bind malonyl-CoA directly and transfer malonyl group from malonyl-CoA to the ACP domain in vitro. Phylogenetic analysis suggested that ScTIOMCAT was relative close to MCATs of yeast strains. Overexpression of ScTIOMCAT in Saccharomyces cereviseae significantly increased the MCAT activity, without negative effects on the growth rate of the host strain. In addition, ScTIOMCAT generated 16.8 and 62 % increase in biomass and fatty acid accumulation, respectively, and did not alter the profile of fatty acid. Our results indicated that the novel MCAT gene from Schizochytrium sp. TIO1101 was crucial for fatty acid synthesis and had potential applications for genetic modifications of oil-producing species.