鞭毛和纤毛

鞭毛和纤毛是原生动物的运动细胞器,它们除了运动功能之外,它们的摆动还可以引起水流、利于取食、推动物质在体内的流动,另外它们也具有某些感觉的功能。多数鞭毛虫具有1—2根鞭毛,长为5—200微米,摆动是对称的,包括几个左右摆动的运动波。纤毛数目很多但较短,一般长3—20微米,运动是不对称的,仅包括一个运动波。

Molecular phylogeny of oligotrich genera Omegastrombidium and Novistrombidium(Protozoa,Ciliophora) for the systematical relationships within Family Strombidiidae

The phylogeny of the oligotrich ciliates is currently a hot debate despite the availability of both morphological and molecular data.In the present paper,further small subunit rRNA(SS rRNA) genes were analyzed from the Genera Omegastrombidium and Novistrombidium,as well as from Strombidium,and combined with three new SS rRNA sequences from Strombidium basimorphum,S.sulcatum population QD-1,and Novistrombidium testaceum population GD.The phylogenetic positions of these organisms were inferred using Bayesian inference,Maximum Likelihood,and Maximum Parsimony methods.The main results are:(1) the SS rRNA gene sequence analyses match the recent findings about the molecular evolution of oligotrichs,indicating that the family Strombidiidae is paraphyletic;(2) the Genus Omegastrombidium is separated from the Genus Strombidium,as shown in recent cladistic analyses;(3) morphospecies in Genus Novistrombidium,based on similarity of somatic ciliature,are separated from each other in all topological trees,indicating that this genus could be a paraphyletic group;(4) the molecular data indicate a possibility of paraphyly for the genus Strombidium;and(5) the similarities of the SS rRNA gene of specimens identified as S.sulcatum and S.inclinatum are 99.8%-100%.However,present knowledge on the oligotrichs sensu stricto is still insufficient and further studies based on both molecular and other technologies are required.

Monophyly or polyphyly? Possible conflict between morphological and molecular interpretations of the wellknown genus Zoothamnium(Ciliophora,Peritrichia)

In this paper, we explore possible conflict between morphological and molecular interpretations of phylogenetic relationships within the well-known peritrichous genus Zoothamnium. On the basis of morphological evidence, for a long time this genus has been believed to be a well-defined monophyletic taxon. Nonetheless, Zoothamnium exhibits higher genetic diversity than the gross morphology of its species. Here, we used all available genetic information for the small subunit of ribosomal RNA （SSU rRNA） and internal transcribed spacer region （ITS1-5.8S-ITS2） for this genus to reconstruct phylogenies for four datasets （SSU rRNA, ITS1, ITS2, and ITS1-5.8S-ITS2） and a combined dataset （SSU rRNA＋ITSI-5.8S- ITS2） using different phylogenetic methods and with consideration of the secondary structure of the genes. Confidence in phylogenetic tree selection was assessed with the approximately unbiased test. The molecular results showed both that Zoothamnium is more likely to be polyphyletic, and morphologically similar genera Zoothamnopsis and Myoschiston were always nested among Zoothamnium species. Accordingly, as with some other groups of ciliates, to understand more fully the correct phylogeny of Zoothamnium there remains a need for additional data from both morphological and molecular studies, covering additional Zoothamnium spp. and members of closely related genera （e.g. Zoothamnopsis, Myoschiston, and Epistylis）.

Molecular Phylogenetic Lineage of Plagiopogon and Askenasia(Protozoa, Ciliophora) Revealed by Their Gene Sequences

Prostomates and haptorians are two basal groups of ciliates with limited morphological characteristics available for tax- onomy. Morphologically, the structures used to identify prostomates and haptorians are similar or even identical, which generate heavy taxonomic and phylogenetic confusion. In present work, phylogenetic positions lineage of two rare genera, Plagiopogon and Askenasia, were investigated. Three genes including small subunit ribosomal RNA gene （hereafter SSU rDNA）, internal transcribed spacer region （ITS region）, and large subunit ribosomal RNA gene （LSU rDNA） were analyzed, 10 new sequences five species each. Our findings included 1） class Prostomatea and order Haptorida are multiphyletic; 2） it may not be appropriate to place order Cyclotriehiida in subclass Haptoria, and the systematic lineage of order Cyclotrichiida needs to be verified further; 3） genus Plagio- pogon branches consistently within a clade covering most prostomes and is basal of clade Colepidae, implying its close lineage to Prostomatea; and 4） Askenasia is phylogenetically distant from the subclass Haptoria but close to classes Prostomatea, Plagiopylea and Oligohymenophorea. We supposed that the toxicyst of Askenasia may be close to taxa of prostomes instead of haptorians, and the dorsal brush is a more typical morphological characteristics of haptorians than toxicysts.

COP9 signalosome subunit PfCsnE regulates secondary metabolism and conidial formation in Pestalotiopsis fici

The COP9 signalosome(CSN) is a highly conserved multiprotein complex in all eukaryotes and involved in regulation of organism development. In filamentous fungi, several lines of evidence indicate that fungal development and secondary metabolism(SM) are mediated by the fifth subunit of CSN, called CsnE. Here we uncover a connection with CsnE and conidial formation as well as SM regulation in the plant endophytic fungus Pestalotiopsis fici. A homology search of the P. fici genome with CsnE, involved in sexual development and SM in Aspergillus nidulans, identified PfCsnE. Deletion of PfcsnE resulted in a mutant that stopped conidial production, but the conidia are recovered in a PfcsnE complemented strain. This indicates that PfCsnE is required for the formation of conidia. Secondary metabolite analysis demonstrated that the ΔPfcsnE strain produced more chloroisosulochrin, less ficiolide A production in comparison to wild type(WT). Transcriptome analysis of WT andΔPfcsnE strains indicated that PfcsnE impacts the expression levels of 8.37% of 14,797 annotated genes. Specifically, nine biosynthetic gene clusters(BGCs) were up-regulated and three BGCs were down-regulated by PfCsnE. Our results suggest that PfCsnE plays major roles in SM regulation and conidial development in P. fici.

Ancient DNA sequences from Coelodonta antiquitatis in China reveal its divergence and phylogeny

Ancient DNA data have supported a sister relationship between woolly rhinoceros and extant Sumatran rhinoceros.This relationship has been used to explore the divergent times for the woolly rhinoceros from their relatives.Complete and partial ancient DNA sequences of the mitochondrial cytochrome b(cyt b)gene were retrieved from bones of the late Pleistocene Coelodonta antiquitatis excavated from northern and northeastern China.The newly obtained sequences together with the European and northern Asian Coelodonta antiquitatis sequences from GenBank were used to estimate the evolutionary divergence time.Phylogenetic analyses showed the exchange of genetic information between the Chinese individuals and Coelodonta antiquitatis of north Asia,which also indicated a more recent evolutionary timescale(3.8–4.7 Ma)than previous molecular estimations(17.5–22.8 or 21–26 Ma)for woolly rhinoceros based on the fossil calibration of outgroups.This new timescale was more consistent with the fossil record of the earliest known genus Coelodonta.