Relationship between morphospecies and microcystin-producing genotypes of Microcystis species in Chinese freshwaters

Twenty water bodies in China were sampled,and 186 strains of different Microcystis species were isolated,from which eight morpho species were identified and 43 stains containing the mcyB gene were detected.Phylogenetic analysis based on the mcyB gene indicated that the microcystin(MC)-producing Microcystis in China could be divided into two groups(ⅠandⅡ)and showed significant differences between the two groups.The maximum sequence similarity was 69.1%.Microcystins(MCs)were measured by high-performance liquid chromatography(HPLC)analysis,and no microcystin-RR(MC-RR)was detected in some strains belonging to GroupⅡ.Compared to other regions of the world,the proportion of Chinese MC-producing was different,and the regional differences were more obvious.A whole-cell polymerase chain reactio(PCR)assay was conducted to analyze the proportion of the mcyB gene in the laboratory cultured and field cultured Microcystis.The proportion of four morphospecies(M.vividis,M.ichthyoblabe,M.novacekii,and M.aeruginosa)that contained the mcyB gene exceeded 50%in the field cultured sample s.Compared with former studies,M.aeruginosa was the mo st likely morphotype that can produce MCs in the world.This study provided new insight of Microcystis hazard assessment and field monitoring.

Metagenome-based analysis:A promising direction for plankton ecological studies

The plankton community plays an especially important role in the functioning of aquatic ecosystems and also in biogeochemical cycles. Since the beginning of marine research expeditions in the 1870s, an enormous number of planktonic organisms have been described and studied. Plankton investigation has become one of the most important areas of aquatic ecological study, as well as a crucial component of aquatic environmental evaluation. Nonetheless, traditional investigations have mainly focused on morphospecies composition, abundances and dynamics, which primarily depend on morphological identification and counting under microscopes. However, for many species/groups, with few readily observable characteristics, morphological identification and counting have historically been a difficult task. Over the past decades, microbiologists have endeavored to apply and extend molecular techniques to address questions in microbial ecology. These culture-independent studies have generated new insights into microbial ecology. One such strategy, metagenome-based analysis, has also proved to be a powerful tool for plankton research. This mini-review presents a brief history of plankton research using morphological and metagenome-based approaches and the potential applications and further directions of metagenomic analyses in plankton ecological studies are discussed. The use of metagenome-based approaches for plankton ecological study in aquatic ecosystems is encouraged.

Diversity of foliar endophytes in wind-fallen Picea abies trees

The unmanaged Norway spruce montane forests in the Bohemian Forest National Park(Czech Republic)suffered from repeated large-scale bark beetle outbreaks in last decade.In this study,the diversity of culturable foliar endophyte microfungi in needles originating from eleven recently wind-fallen trees in this area was surveyed.Our aims were to describe their diversity and to determine the relative host and organ specificities of isolated endophyte species to estimate the species pool and abundance of foliar endophytes before the forest degradation.Microfungi were isolated from surface-sterilized needles,and the outgrowing strains were identified based on morphological and molecular characteristics(analyses of ITS1,ITS2 and partial 28S rDNA).Fungal communities in the needles were diverse,with ascomycetes(mostly anamorphs of Helotiales)dominating basidiomycetes.The most frequent species(Phacidiopycnis sp.,Cistella acuum,Sirococcus sp.and two species of Chalara)did not correspond with those recorded in previous studies of Picea spp.For example,the widely distributed Lophodermium piceae was rarely recorded in this study.This pattern may be caused by different methods of sterilization and cultivation or by physiological characteristics of the needles,or it may reflect the species distribution in the studied area.Members of the Helotiales,along with sequences from GenBank,showed substantial overlap in host affinities,most prominently between Pinus and Picea,and also among species from distant plant lineages.

Fusulinid species determination based on population variation:An example from Eopolydiexodina

To make fusulinid morphospecies more accordant with biological species, it is necessary and reasonable to constrain the conventional determination of fusulinid species with population-level morphological variation. As an example, morphospecies identification on population level was conducted on Eopolydiexodina specimens from a single bed of the Middle Permian Shazipo Formation of Xiaoxinzhai Section in western Yunnan, China. These specimens were identified with the consideration of fossil population by morphometric analysis of their characteristic morphological variates (diameter of proloculus, size and ratio of inner and outer volutions). The results reveal that the studied variates have wide but overall continuous variation and generally follow the normal distribution. The studied individuals, therefore, have consistent morphological variation with a single population and should belong to one fusulinid morphospecies. This study supports the assumption that fusulinid individuals of one genus from the same bed in one locality should constitute a single fossil population.

Species richness estimations of the megadiverse scuttle fly genus Megaselia （Diptera： Phoridae） in a wildfire-affected hemiboreal forest

The species richness of the scuttle fly （Diptera： Phoridae） genus Megaselia was estimated by various non-parametric estimators from EstimateS, Species Prediction And Diversity Estimation （SPADE） and Ws2m, based on material from a Swedish hemiboreal forest area recently affected by major wildfires, Yyresta National Park and Nature Reserve （TNPNR）, south of Stockholm. A total of 21 249 individuals were collected in Malaise traps, of which males constituted 16 976 and females 4 273. The analysed dataset represents 37 samples containing 18 549 specimens sorted into 330 species （184 described, 146 are either undescribed or of unsettled taxonomic status）. It was not possible to estimate the total species richness using all samples due to heterogeneity caused by inclusion of different communities and temporal incoherencies between samples within and between years. Even with material obtained from a sampling program that was not designed for species richness estimates, it was possible to obtain reliable results when sample heterogeneity was minimized. By dividing the data into community-specific datasets - for bog, forest and wildfire - it was possible to obtain asymptotic curves for the smaller of the two wildfire datasets. A total estimate of 357~439 （95% CI） was attained by using the smaller wildfire dataset and adding the 85 unique species from the samples not included in the estimation analysis. TNPNR has one of the richest known scuttle fly communities in Europe, consisting of almost 50% of the currently named Megaselia species; 48 of these species are reported as new records for Sweden in this study.