Molecular and pathological characterization of Fusarium solani species complex infection in the head and lateral line system of Sphyrna lewini

A severe fungal infection affecting the head and lateral line system was diagnosed in 7 captive scalloped hammerhead sharks Sphyrna lewini in an aquarium in Thailand. Extensive and severe necrotizing cellulitis was consistently observed microscopically along the cephalic and lateral line canals in conjunction with positive fungal cultures for Fusarium sp. Molecular phylogenetic analysis was performed from 3 isolates based on the nucleotide sequences containing internally transcribed spacer (ITS) and a portion of 5.8S and 28S rDNA. The fungus was highly homologous (100%) and closely related to F. solani species complex 2 (FSSC 2), which belongs to Clade 3 of the FSSC. Our results illustrate the histopathological findings and expand upon our knowledge of the prevalence of invasive fusariosis in the head and lateral line system of hammerhead sharks.

An evolutionary classification of genomic function

The pronouncements of the ENCODE Project Consortium regarding "junk DNA" exposed the need for an evolutionary classification of genomic elements according to their selected-effect function. In the classification scheme presented here, we divide the genome into "functional DNA," that is, DNA sequences that have a selected-effect function, and "rubbish DNA," that is, sequences that do not. Functional DNA is further subdivided into "literal DNA" and "indifferent DNA." In literal DNA, the order of nucleotides is under selection; in indifferent DNA, only the presence or absence of the sequence is under selection. Rubbish DNA is further subdivided into "junk DNA" and "garbage DNA." Junk DNA neither contributes to nor detracts from the fitness of the organism and, hence, evolves under selective neutrality. Garbage DNA, on the other hand, decreases the fitness of its carriers. Garbage DNA exists in the genome only because natural selection is neither omnipotent nor instantaneous. Each of these four functional categories can be 1) transcribed and translated, 2) transcribed but not translated, or 3) not transcribed. The affiliation of a DNA segment to a particular functional category may change during evolution: Functional DNA may become junk DNA, junk DNA may become garbage DNA, rubbish DNA may become functional DNA, and so on; however, determining the functionality or nonfunctionality of a genomic sequence must be based on its present status rather than on its potential to change (or not to change) in the future. Changes in functional affiliation are divided into pseudogenes, Lazarus DNA, zombie DNA, and Jekyll-to-Hyde DNA.

Does the cosmopolitan diatom Gomphonema parvulum (Kützing) Kützing have a biogeography?

Diatom cultures of the G. parvulum species complex were established from seven different sites in the Faroe Islands, Sweden, Germany, Mexico and Korea, and were studied in detail. Eight morphodemes were identified which corresponded to the descriptions of the cosmopolitan taxon G. parvulum (Kützing) Kützing sensu lato: its nominate variety (var. parvulum), G. parvulum var. exilissimum Grunow and G. parvulum f. saprophilum Lange-Bertalot & Reichardt, G. [parvulum var.] lagenula Kützing plus four unidentifiable morphodemes. The concatenated analysis of the sequences of the markers 18SV4, rbcL, and ITS as well as morphological data resulted in a separation of four taxa based on their biogeography in Mexico, Korea, central Continental Europe and Northern Atlantic Europe. Mantel tests showed a significant correlation between molecular and geographical distances. The diagnoses of two taxa, G. parvulum sensu stricto, and G. lagenula, were emended, G. saprophilum elevated to species rank and epitypes designated. One species was newly described.

Repeated evolution of fungal cultivar specificity in independently evolved ant-plant-fungus symbioses

Some tropical plant species possess hollow structures (domatia) occupied by ants that protect the plant and in some cases also provide it with nutrients. Most plant-ants tend patches of chaetothyrialean fungi within domatia. In a few systems it has been shown that the ants manure the fungal patches and use them as a food source, indicating agricultural practices. However, the identity of these fungi has been investigated only in a few samples. To examine the specificity and constancy of ant-plant-fungus interactions we characterised the content of fungal patches in an extensive sampling of three ant-plant symbioses (Petalomyrmex phylax/Leonardoxa africana subsp. africana, Aphomomyrmex afer/Leonardoxa africana subsp. letouzeyi and Tetraponera aethiops/Barteria fistulosa) by sequencing the Internal Transcribed Spacers of ribosomal DNA. For each system the content of fungal patches was constant over individuals and populations. Each symbiosis was associated with a specific, dominant, primary fungal taxon, and to a lesser extent, with one or two specific secondary taxa, all of the order Chaetothyriales. A single fungal patch sometimes contained both a primary and a secondary taxon. In one system, two founding queens were found with the primary fungal taxon only, one that was shown in a previous study to be consumed preferentially. Because the different ant-plant symbioses studied have evolved independently, the high specificity and constancy we observed in the composition of the fungal patches have evolved repeatedly. Specificity and constancy also characterize other cases of agriculture by insects.

Fungi in Thailand: a case study of the efficacy of an ITS barcode for automatically identifying species within the Annulohypoxylon and Hypoxylon genera

Thailand, a part of the Indo-Burma biodiversity hotspot, has many endemic animals and plants. Some of its fungal species are difficult to recognize and separate, complicating assessments of biodiversity. We assessed species diversity within the fungal genera Annulohypoxylon and Hypoxylon, which produce biologically active and potentially therapeutic compounds, by applying classical taxonomic methods to 552 teleomorphs collected from across Thailand. Using probability of correct identification (PCI), we also assessed the efficacy of automated species identification with a fungal barcode marker, ITS, in the model system of Annulohypoxylon and Hypoxylon. The 552 teleomorphs yielded 137 ITS sequences; in addition, we examined 128 GenBank ITS sequences, to assess biases in evaluating a DNA barcode with GenBank data. The use of multiple sequence alignment in a barcode database like BOLD raises some concerns about non-protein barcode markers like ITS, so we also compared species identification using different alignment methods. Our results suggest the following. (1) Multiple sequence alignment of ITS sequences is competitive with pairwise alignment when identifying species, so BOLD should be able to preserve its present bioinformatics workflow for species identification for ITS, and possibly therefore with at least some other non-protein barcode markers. (2) Automated species identification is insensitive to a specific choice of evolutionary distance, contributing to resolution of a current debate in DNA barcoding. (3) Statistical methods are available to address, at least partially, the possibility of expert misidentification of species. Phylogenetic trees discovered a cryptic species and strongly supported monophyletic clades for many Annulohypoxylon and Hypoxylon species, suggesting that ITS can contribute usefully to a barcode for these fungi. The PCIs here, derived solely from ITS, suggest that a fungal barcode will require secondary markers in Annulohypoxylon and Hypoxylon, however. The URL http://tinyurl.com/spouge-barcode contains computer programs and other supplementary material relevant to this article.

Characterization of the vaginal micro- and mycobiome in asymptomatic reproductive-age Estonian women

The application of high-throughput sequencing methods has raised doubt in the concept of the uniform healthy vaginal microbiota consisting predominantly of lactobacilli by revealing the existence of more variable bacterial community composition. As this needs to be analyzed more extensively and there is little straightforward data regarding the vaginal mycobiome of asymptomatic women we aimed to define bacterial and fungal communities in vaginal samples from 494 asymptomatic, reproductive-age Estonian women. The composition of the vaginal microbiota was determined by amplifying bacterial 16S rRNA and fungal internal transcribed spacer-1 (ITS-1) regions and subsequently sequencing them using 454 Life Sciences pyrosequencing. We delineated five major bacterial community groups with distinctive diversity and species composition. Lactobacilli were among the most abundant bacteria in all groups, but also members of genus Gardnerella had high relative abundance in some of the groups. Microbial diversity increased with higher vaginal pH values, and was also higher when a malodorous discharge was present, indicating that some of the women who consider themselves healthy may potentially have asymptomatic bacterial vaginosis (BV). Our study is the first of its kind to analyze the mycobiome that colonizes the healthy vaginal environment using barcoded pyrosequencing technology. We observed 196 fungal operational taxonomic units (OTUs), including 16 OTUs of Candida spp., which is more diverse than previously recognized. However, assessing true fungal diversity was complicated because of the problems regarding the possible air-borne contamination and bioinformatics used for identification of fungal taxons as significant proportion of fungal sequences were assigned to unspecified OTUs.

[Grass genome and chromosome sets evolution]

This paper briefly discusses the mechanisms by which either diploid 2n or basal chromosome number x change during grass karyotype evolution.

Combined analyses of the ITS loci and the corresponding 16S rRNA genes reveal high micro- and macrodiversity of SAR11 populations in the Red Sea

Bacteria belonging to the SAR11 clade are among the most abundant prokaryotes in the pelagic zone of the ocean. 16S rRNA gene-based analyses indicate that they constitute up to 60% of the bacterioplankton community in the surface waters of the Red Sea. This extremely oligotrophic water body is further characterized by an epipelagic zone, which has a temperature above 24 °C throughout the year, and a remarkable uniform temperature (~22 °C) and salinity (~41 psu) from the mixed layer (~200 m) to the bottom at over 2000 m depth. Despite these conditions that set it apart from other marine environments, the microbiology of this ecosystem is still vastly understudied. Prompted by the limited phylogenetic resolution of the 16S rRNA gene, we extended our previous study by sequencing the internal transcribed spacer (ITS) region of SAR11 in different depths of the Red Sea's water column together with the respective 16S fragment. The overall diversity captured by the ITS loci was ten times higher than that of the corresponding 16S rRNA genes. Moreover, species estimates based on the ITS showed a highly diverse population of SAR11 in the mixed layer that became diminished in deep isothermal waters, which was in contrast to results of the related 16S rRNA genes. While the 16S rRNA gene-based sequences clustered into three phylogenetic subgroups, the related ITS fragments fell into several phylotypes that showed clear depth-dependent shifts in relative abundances. Blast-based analyses not only documented the observed vertical partitioning and universal co-occurrence of specific phylotypes in five other distinct oceanic provinces, but also highlighted the influence of ecosystem-specific traits (e.g., temperature, nutrient availability, and concentration of dissolved oxygen) on the population dynamics of this ubiquitous marine bacterium.

Genetic relationships among Rehmannia glutinosa cultivars and varieties

Many cultivars of Rehmannia glutinosa are grown in China for medicinal uses, but detailed agronomic and morphological descriptions are available for only a few. Knowledge of genetic relationships among most of the cultivars is also scanty and poorly documented. Here, cultivars, varieties and some sexually produced seeds of R. GLUTINOSA were raised in the field and studied for morphological diversity including shape, color, edges of leaves, color of anther, cornal and root, as well as yield of the medicinal part of the roots. Random amplified polymorphism DNA (RAPD) and amplified fragment length polymorphism (AFLP) were used to determine genetic relationships and ribosome DNA internal transcribed spacer (ITS) sequences were used for analyzing sequence variations and phylogenetic history. The 118 and 1019 polymorphic markers produced by 10 RAPD and 8 AFLP primers discriminated cultivars and varieties satisfactorily. Sixty-eight accessions were clustered in three main groups at 0.69 similarity levels by unweighted pair-group method arithmetic average (UPGMA) cluster analysis using RAPD in combination with AFLP markers. The average polymorphism information content (PIC) and Shannon index were 0.438 and 2.19 in RAPD and 0.476 and 26.68 in AFLP primers, respectively. This indicates that AFLP markers would be more efficient than RAPD for screening large numbers of R. GLUTINOSA accessions. The analysis of ITS sequences indicated that ITS1 - 5.8S-ITS2 of R. GLUTINOSA was informative in its 611 - 614-bp-long sequence and had 106 variable sites. Phylogenetic trees generated based on ITS sequences as well as the dendrogram obtained from two molecular markers identified four accessions: BY3, BY5, BY6 and Wildness6, with great genetic divergence.

Seasonal influences on fungal community structure in unimproved and improved upland grassland soils

Seasonal and management influences on the fungal community structure of two upland grassland soils were investigated. An upland site containing both unimproved floristically diverse (U4a) and improved mesotrophic (MG7b) grassland types was selected. Samples from both grassland types were taken at five times in one year. Soil fungal community structure was assessed using fungal automated ribosomal intergenic spacer analysis (ARISA), a DNA-profiling approach. A grassland management regime was found to strongly affect fungal community structure, with fungal ARISA profiles from unimproved and improved grassland soils differing significantly. The number of fungal ribotypes found was higher in unimproved than improved grassland soils, providing evidence that improvement may reduce the suitability of upland soil as a habitat for specific groups of fungi. Seasonal influences on fungal community structure were also noted, with samples taken in autumn (October) more correlated with change in ribotype profiles than samples from other seasons. However, seasonal variation did not obscure the measurement of differences in the fungal community structure that were due to agricultural improvement, with canonical correspondence analysis indicating grassland type had a stronger influence on fungal profiles than did season.Key words: upland grasslands, fungal automated ribosomal intergenic spacer analysis, seasonality, improvement, canonical correspondence analysis.

Noncoding sequences conserved in a limited number of mammals in the SIM2 interval are frequently functional

Cross-species DNA sequence comparison is a fundamental method for identifying biologically important elements, because functional sequences are evolutionarily conserved, wheres nonfunctional sequences drift. A recent genome-wide comparison of human and mouse DNA discovered over 200,000 conserved noncoding sequences with unknown function. Multispecies DNA comparison has been proposed as a method to prioritize these conserved noncoding sequences for functional analysis based on the hypothesis that elements present in many species are more likely to be functional than elements present in limited numbers of species. Here, we perform a comparative analysis of the single-minded 2 (SIM2) gene interval on human chromosome 21 with horse, cow, pig, dog, cat, and mouse DNA. We classify conserved sequences based on the number of mammals in which they are present, and experimentally test sequences in each class for function. As hypothesized, conserved sequences present in many mammals are frequently functional. Additionally, we demonstrate that sequences conserved in a limited number of mammals are also frequently functional. Examination of genomic deletions in chimpanzee and rhesus macaque DNA showed that several putatively functional conserved noncoding human sequences were absent in these primates. These findings suggest that functional conserved noncoding human sequences can be missing in other mammals, even closely related primate species.

Molecular sequence analyses of the intergenic spacer (IGS) associated with rDNA of the two varieties of the pathogenic yeast, Cryptococcus neoformans

The pathogen Crytococcus neoformans has been traditionally grouped in two varieties, C. neoforrmans var. neoformans (serotypes A, D and AD) and C. neoformans var. gattii (serotypes B and C). A recent taxonomic evaluation of C. neoformans var. neoformans described C. neoformans var. grubii as a new variety represented by serotype A isolates. Despite immunological, biochemical, ecological and molecular differences the three varieties are classified within one species. We examined the genetic variability of one hundred and five clinical and environmental isolates that included all varieties and serotypes. Sequence analysis of the intergenic spacer (IGS) associated with rDNA revealed significant differences in nucleotide composition between and within the varieties. Parsimony analysis showed five different genotypes representing distinct genetic lineages. Although there was a high degree of relatedness between serotype and genotype this relatedness was not exclusive as serotypes were not restricted to one particular genotypic group. Serotyping and sequence analyses indicate that C. neoformans var. grubii (serotype A) should not be recognized as a separate variety. Based on this study we propose to accept two separate species, C. neoformans (serotypes A, D and AD) and C. bacillisporus (serotypes B and C synonymous with C. neoformans var. gattii).