Symbiotic microbes play a variety of fundamental roles in the health and habitat ranges of their hosts. While prokaryotes in marine sponges have been broadly characterized, the diversity of sponge-inhabiting fungi has barely been explored using molecular approaches. Fungi are an important component of many marine and terrestrial ecosystems, and they may be an ecologically significant group in sponge-microbe interactions. This study tested the feasibility of using existing fungal primers for molecular analysis of sponge-associated fungal communities. None of the eight selected primer pairs yielded satisfactory results in fungal rRNA gene or internal transcribed spacer (ITS) clone library constructions. However, 3 of 10 denaturing gradient gel electrophoresis (DGGE) primer sets, which were designed to preferentially amplify fungal rRNA gene or ITS regions from terrestrial environmental samples, were successfully amplified from fungal targets in marine sponges. DGGE analysis indicated that fungal communities differ among different sponge species (Suberites zeteki and Mycale armata) and also vary between sponges and seawater. Sequence analysis of DGGE bands identified 23 and 21 fungal species from each of the two sponge species S. zeteki and M. armata, respectively. These species were representatives of 11 taxonomic orders and belonged to the phyla of Ascomycota (seven orders) and Basidiomycota (four orders). Five of these taxonomic orders (Malasseziales, Corticiales, Polyporales, Agaricales, and Dothideomycetes et Chaetothyriomcetes incertae sedis) have now been identified for the first time in marine sponges. Seven and six fungal species from S. zeteki and M. armata, respectively, are potentially new species because of their low sequence identity (<98%) with their references in GenBank. Phylogenetic analysis indicated sponge-derived sequences were clustered into "marine fungus clades" with those from other marine habitats. This is the first report of molecular analysis of fungal communities in marine sponges, adding depth and dimension to our understanding of sponge-associated microbial communities.

Maternal effect genes play critical roles in early embryogenesis of model organisms where they have been intensively investigated. However, their molecular function in mammals remains largely unknown. Recently, we identified a subcortical maternal complex (SCMC) that contains four proteins encoded by maternal effect genes (Mater, Filia, Floped and Tle6). Here we report that TLE6, similar to FLOPED and MATER, stabilizes the SCMC and is necessary for cleavage beyond the two-cell stage of development. We document that the SCMC is required for formation of the cytoplasmic F-actin meshwork that controls the central position of the spindle and ensures symmetric division of mouse zygotes. We further demonstrate that the SCMC controls formation of the actin cytoskeleton specifically via Cofilin, a key regulator of F-actin assembly. Our results provide molecular insight into the physiological function of TLE6, its interaction with the SCMC and their roles in the symmetric division of the zygote in early mouse development.

Summary• The transcription factors C-repeat binding factors/dehydration-responsive element binding proteins (CBFs/DREBs) control the expression of many stress-inducible genes in Arabidopsis.• A cDNA clone, designated GhDREB1 , was isolated from cotton ( Gossypium hirsutum ) by cDNA library screening.• Northern blot analysis indicated that mRNA accumulation of GhDREB1 was induced by low temperatures and salt stress, but was not induced by abscisic acid (ABA) or drought stress in cotton seedlings. Transgenic tobacco ( Nicotiana tabacum ) plants overexpressing GhDREB1 displayed stronger chilling tolerance than wild-type plants. Their leaf chlorophyll fluorescence, net photosynthetic rate and proline concentrations were higher than those of control plants during low-temperature treatment. However, under normal growth conditions, the transgenic tobacco plants exhibited retarded growth and delayed flowering. Interestingly, GhDREB1 transcripts in cotton seedlings were negatively regulated by gibberellic acid (GA 3 ) treatment. Analysis of the promoter of the GhDREB1 gene revealed the presence of one low-temperature and four gibberellin-responsive elements. Green fluorescent protein (GFP) signal intensity or β -glucuronidase (GUS) activity driven by the GhDREB1 promoter was clearly enhanced by low temperature but repressed by GA 3 .• These results suggest that GhDREB1 functions as a transcription factor and plays an important role in improving cold tolerance, and also affects plant growth and development via GA 3 .

Microbial community diversity and composition have critical biogeochemical roles in the functioning of marine ecosystems. Large populations of planktonic fungi exist in coastal ocean waters, yet their diversity and role in carbon and nutrient cycling remain largely unknown. Lack of information on critical functional microbial groups limits our understanding of their ecological roles in coastal oceans and hence our understanding of its functioning in the ocean's carbon and nutrient cycles. To address this gap, this study applied the molecular approach denaturing gradient gel electrophoresis (DGGE) coupled with clone library construction to investigate mycoplankton communities in Hawaiian coastal waters. Mycoplankton communities displayed distinct lateral and vertical variations in diversity and composition. Compared with the open ocean, surface (o100 m) near-shore waters had the greatest diversity and species richness of mycoplankton, whereas no differences were found among stations at depths below 150 m. Vertical diversity profiles in the coastal waters suggested that diversity and species richness were positively correlated to phytoplankton biomass in the coastal waters, but not in offshore waters. A total of 46 species were identified and belonging to two phyla Basidiomycota and Ascomycota, with the basidiomycetes as the dominant group (n ¼ 42). The majority (n ¼ 27) of the basidiomycetes are novel phylotypes showing less than 98% identity in the 18S rRNA gene with any sequence in GenBank. This study provides insight into mycoplankton ecology and is the first molecular analysis of planktonic fungi in the oceans. The ISME Journal (

BackgroundSoil microorganisms can mediate the occurrence of plant diseases. Potato common scab (CS) is a refractory disease caused by pathogenic Streptomyces that occurs worldwide, but little is known about the interactions between CS and the soil microbiome. In this study, four soil-root system compartments (geocaulosphere soil (GS), rhizosphere soil (RS), root-zone soil (ZS), and furrow soil (FS)) were analyzed for potato plants with naturally high (H) and low (L) scab severity levels. We aimed to determine the composition and putative function of the soil microbiome associated with potato CS.ResultsThe copy numbers of the scab phytotoxin biosynthetic gene txtAB and the bacterial 16S rRNA gene as well as the diversity and composition of each of the four soil-root system compartments were examined; GS was the only compartment that exhibited significant differences between the H and L groups. Compared to the H group, the L group exhibited a lower txtAB gene copy number, lower bacterial 16S copy number, higher diversity, higher co-occurrence network complexity, and higher community function similarity within the GS microbiome. The community composition and function of the GS samples were further revealed by shotgun metagenomic sequencing. Variovorax, Stenotrophomonas, and Agrobacterium were the most abundant genera that were significantly and positively correlated with the scab severity level, estimated absolute abundance (EAA) of pathogenic Streptomyces, and txtAB gene copy number. In contrast, Geobacillus, Curtobacterium, and unclassified Geodermatophilaceae were significantly negatively correlated with these three parameters. Compared to the function profiles in the L group, several genes involved in “ABC transporters,” the “bacterial secretion system,” “quorum sensing (QS),” “nitrogen metabolism,” and some metabolism by cytochrome P450 were enriched in the H group. In contrast, some antibiotic biosynthesis pathways were enriched in the L group. Based on the differences in community composition and function, a simple model was proposed to explain the putative relationships between the soil microbiome and CS occurrence.ConclusionsThe GS microbiome was closely associated with CS severity in the soil-root system, and the occurrence of CS was accompanied by changes in community composition and function. The differential functions provide new clues to elucidate the mechanism underlying the interaction between CS occurrence and the soil microbiome, and varying community compositions provide novel insights into CS occurrence.Electronic supplementary materialThe online version of this article (10.1186/s40168-019-0629-2) contains supplementary material, which is available to authorized users.

No abstract

Breast cancer amplified sequence 2 (BCAS2) is involved in multiple biological processes, including pre-mRNA splicing. However, the physiological roles of BCAS2 are still largely unclear. Here we report that BCAS2 is specifically enriched in spermatogonia of mouse testes. Conditional disruption of Bcas2 in male germ cells impairs spermatogenesis and leads to male mouse infertility. Although the spermatogonia appear grossly normal, spermatocytes in meiosis prophase I and meiosis events (recombination and synapsis) are rarely observed in the BCAS2-depleted testis. In BCAS2 null testis, 245 genes are altered in alternative splicing forms; at least three spermatogenesis-related genes (Dazl, Ehmt2 and Hmga1) can be verified. In addition, disruption of Bcas2 results in a significant decrease of the full-length form and an increase of the short form (lacking exon 8) of DAZL protein. Altogether, our results suggest that BCAS2 regulates alternative splicing in spermatogonia and the transition to meiosis initiation, and male fertility.

Mitogen-activated protein kinase (MAPK) cascades play important roles in mediating biotic and abiotic stress responses. In plants, MAPKs are classified into four major groups (A-D) according to their sequence homology and conserved phosphorylation motifs. Compared with well-studied MAPKs in groups A and B, little is known about group C. In this study, we functionally characterised a stress-responsive group C MAPK gene (GhMPK2) from cotton (Gossypium hirsutum). Northern blot analysis indicated that GhMPK2 was induced by abscisic acid (ABA) and abiotic stresses, such as NaCl, PEG, and dehydration. Subcellular localization analysis suggested that GhMPK2 may activate its specific targets in the nucleus. Constitutive overexpression of GhMPK2 in tobacco (Nicotiana tabacum) conferred reduced sensitivity to ABA during both seed germination and vegetative growth. Interestingly, transgenic plants had a decreased rate of water loss and exhibited enhanced drought and salt tolerance. Additionally, transgenic plants showed improved osmotic adjustment capacity, elevated proline accumulation and up-regulated expression of several stress-related genes, including DIN1, Osmotin and NtLEA5. β-glucuronidase (GUS) expression driven by the GhMPK2 promoter was clearly enhanced by treatment with NaCl, PEG, and ABA. These results strongly suggest that GhMPK2 positively regulates salt and drought tolerance in transgenic plants.