Kingdom protozoa and its 18 phyla.

The demarcation of protist kingdoms is reviewed, a complete revised classification down to the level of subclass is provided for the kingdoms Protozoa, Archezoa, and Chromista, and the phylogenetic basis of the revised classification is outlined. Removal of Archezoa because of their ancestral absence of mitochondria, peroxisomes, and Golgi dictyosomes makes the kingdom Protozoa much more homogeneous: they all either have mitochondria and peroxisomes or have secondarily lost them. Predominantly phagotrophic, Protozoa are distinguished from the mainly photosynthetic kingdom Chromista (Chlorarachniophyta, Cryptista, Heterokonta, and Haptophyta) by the absence of epiciliary retronemes (rigid thrust-reversing tubular ciliary hairs) and by the lack of two additional membranes outside their chloroplast envelopes. The kingdom Protozoa has two subkingdoms: Adictyozoa, without Golgi dictyosomes, containing only the phylum Percolozoa (flagellates and amoeboflagellates); and Dictyozoa, made up of 17 phyla with Golgi dictyosomes. Dictyozoa are divided into two branches: (i) Parabasalia, a single phylum with hydrogenosomes and 70S ribosomes but no mitochondria, Golgi dictyosomes associated with striated roots, and a kinetid of four or five cilia; and (ii) Bikonta (16 unicellular or plasmodial phyla with mitochondria and bikinetids and in which Golgi dictyosomes are not associated with striated ciliary roots), which are divided into two infrakingdoms: Euglenozoa (flagellates with discoid mitochondrial cristae and trans-splicing of miniexons for all nuclear genes) and Neozoa (15 phyla of more advanced protozoa with tubular or flat [usually nondiscoid] mitochondrial cristae and cis-spliced spliceosomal introns). Neozoa are divided into seven parvkingdoms: (i) Ciliomyxa (three predominantly ciliated phyla with tubular mitochondrial cristae but no cortical alveoli, i.e., Opalozoa [flagellates with tubular cristae], Mycetozoa [slime molds], and Choanozoa [choanoflagellates, with flattened cristae]); (ii) Alveolata (three phyla with cortical alveoli and tubular mitochondrial cristae, i.e., Dinozoa [Dinoflagellata and Protalveolata], Apicomplexa, and Ciliophora); (iii) Neosarcodina (phyla Rhizopoda [lobose and filose amoebae] and Reticulosa [foraminifera; reticulopodial amoebae], usually with tubular cristae); (iv) Actinopoda (two phyla with axopodia: Heliozoa and Radiozoa [Radiolaria, Acantharia]); (v) Entamoebia (a single phylum of amoebae with no mitochondria, peroxisomes, hydrogenosomes, or cilia and with transient intranuclear centrosomes); (vi) Myxozoa (three endoparasitic phyla with multicellular spores, mitochondria, and no cilia: Myxosporidia, Haplosporidia, and Paramyxia); and (vii) Mesozoa (multicells with tubular mitochondrial cristae, included in Protozoa because, unlike animals, they lack collagenous connective tissue).     

Phylogeny of Choanozoa,Apusozoa, and Other Protozoa and Early Eukaryote Megaevolution

Abstract The primary diversification of eukaryotes involved protozoa, especially zooflagellates—flagellate protozoa without plastids. Understanding the origins of the higher eukaryotic kingdoms (two purely heterotrophic, Animalia and Fungi, and two primarily photosynthetic, Plantae and Chromista) depends on clarifying evolutionary relationships among the phyla of the ancestral kingdom Protozoa. We therefore sequenced 18S rRNA genes from 10 strains from the protozoan phyla Choanozoa and Apusozoa. Eukaryote diversity is encompassed by three early-radiating, arguably monophyletic groups: Amoebozoa, opisthokonts, and bikonts. Our taxon-rich rRNA phylogeny for eukaryotes allowing for intersite rate variation strongly supports the opisthokont clade (animals, Choanozoa, Fungi). It agrees with the view that Choanozoa are sisters of or ancestral to animals and reveals a novel nonflagellate choanozoan lineage, Ministeriida, sister either to choanoflagellates, traditionally considered animal ancestors, or to animals. Maximum likelihood trees suggest that within animals Placozoa are derived from medusozoan Cnidaria (we therefore place Placozoa as a class within subphylum Medusozoa of the Cnidaria) and hexactinellid sponges evolved from demosponges. The bikont and amoebozoan radiations are both very ill resolved. Bikonts comprise the kingdoms Plantae and Chromista and three major protozoan groups: alveolates, excavates, and Rhizaria. Our analysis weakly suggests that Apusozoa, represented by Ancyromonas and the apusomonads (Apusomonas and the highly diverse and much more ancient genus Amastigomonas, from which it evolved), are not closely related to other Rhizaria and may be the most divergent bikont lineages. Although Ancyromonas and apusomonads appear deeply divergent in 18S rRNA trees, the trees neither refute nor support the monophyly of Apusozoa. The bikont phylum Cercozoa weakly but consistently appears as sister to Retaria (Foraminifera; Radiolaria), together forming a hitherto largely unrecognized major protozoan assemblage (core Rhizaria) in the eukaryote tree. Both 18S rRNA sequence trees and a rare deletion show that nonciliate haplosporidian and paramyxid parasites of shellfish (together comprising the Ascetosporea) are not two separate phyla, as often thought, but part of the Cercozoa, and may be related to the plant-parasitic plasmodiophorids and phagomyxids, which were originally the only parasites included in the Cercozoa. We discuss rRNA trees in relation to other evidence concerning the basal diversification and root of the eukaryotic tree and argue that bikonts and opisthokonts, at least, are holophyletic. Amoebozoa and bikonts may be sisters—jointly called anterokonts, as they ancestrally had an anterior cilium, not a posterior one like opisthokonts; this contrasting ciliary orientation may reflect a primary divergence in feeding mode of the first eukaryotes. Anterokonts also differ from opisthokonts in sterol biosynthesis (cycloartenol versus lanosterol pathway), major exoskeletal polymers (cellulose versus chitin), and mitochondrial cristae (ancestrally tubular not flat), possibly also primary divergences.     

Early evolution of eukaryote feeding modes,cell structural diversity,and classification of the protozoan phyla Loukozoa,Sulcozoa, and Choanozoa

I discuss how different feeding modes and related cellular structures map onto the eukaryote evolutionary tree. Centrally important for understanding eukaryotic cell diversity are Loukozoa: ancestrally biciliate phagotrophic protozoa possessing a posterior cilium and ventral feeding groove into which ciliary currents direct prey. I revise their classification by including all anaerobic Metamonada as a subphylum and adding Tsukubamonas. Loukozoa, often with ciliary vanes, are probably ancestral to all protozoan phyla except Euglenozoa and Percolozoa and indirectly to kingdoms Animalia, Fungi, Plantae, and Chromista. I make a new protozoan phylum Sulcozoa comprising subphyla Apusozoa (Apusomonadida, Breviatea) and Varisulca (Diphyllatea; Planomonadida, Discocelida, Mantamonadida; Rigifilida). Understanding sulcozoan evolution clarifies the origins from them of opisthokonts (animals, fungi, Choanozoa) and Amoebozoa, and their evolutionary novelties; Sulcozoa and their descendants (collectively called podiates) arguably arose from Loukozoa by evolving posterior ciliary gliding and pseudopodia in their ventral groove. I explain subsequent independent cytoskeletal modifications, accompanying further shifts in feeding mode, that generated Amoebozoa, Choanozoa, and fungi. I revise classifications of Choanozoa, Conosa (Amoebozoa), and basal fungal phylum Archemycota. I use Choanozoa, Sulcozoa, Loukozoa, and Archemycota to emphasize the need for simply classifying ancestral (paraphyletic) groups and illustrate advantages of this for understanding step-wise phylogenetic advances.     

Phylogenetic relationships among eukaryotic kingdoms inferred from ribosomal RNA sequences

Summary Phylogenetic trees among eukaryotic kingdoms were inferred for large- and small-subunit rRNAs by using a maximum-likelihood method developed by Felsenstein. Although Felsenstein's method assumes equal evolutionary rates for transitions and transversions, this is apparently not the case for these data. Therefore, only transversiontype substitutions were taken into account. The molecules used were large-subunit rRNAs fromXenopus laevis (Animalia), rice (Plantae),Saccharomyces cerevisiae (Fungi),Dictyostelium discoideum (Protista), andPhysarum polycephalum (Protista); and small-subunit rRNAs from maize (Plantae),S. cerevisiae, X. laevis, rat (Animalia), andD. discoideum. Only conservative regions of the nucleotide sequences were considered for this study. In the maximum-likelihood trees for both large- and small-subunit rRNAs, Animalia and Fungi were the most closely related eukaryotic kingdoms, and Plantae is the next most closely related kingdom, although other branching orders among Plantae, Animalia, and Fungi were not excluded by this work. These three eukaryotic kingdoms apparently shared a common ancestor after the divergence of the two species of Protista,D. discoideum andP. polycephalum. These two species of Protista do not form a clade, andP. polycephalum diverged first andD. discoideum second from the line leading to the common ancestor of Plantae, Animalia, and Fungi. The sequence data indicate that a drastic change occurred in the nucleotide sequences of rRNAs during the evolutionary separation between prokaryote and eukaryote.     

How many species of algae are there? A reprise. Four kingdoms, 14 phyla, 63 classes and still growing

To date (1 November 2023), the online database AlgaeBase has documented 50,589 species of living algae and 10,556 fossil species here referred to four kingdoms (Eubacteria, Chromista, Plantae, and Protozoa), 14 phyla, and 63 classes. The algae are the third most speciose grouping of plant-like organisms after the flowering plants (≈382,000 species) and fungi (≈170,000 species, including lichens) but are the least well defined of all the botanical groupings. Priority is given to phyla and class names that are familiar to phycologists and that are nomenclaturally valid. The most species-rich phylum is the Heterokontophyta to which 18 classes are referred with 21,052 living species and which is dominated by the diatoms in three classes with 18,673 species (16,427 living; 2239 fossil). The next most species-rich phyla are the red algae (7276 living), the green algae (6851 living), the blue-green algae (Cyanobacteria, 5723 living), the charophytes (4950 living, including the Charophyceae, 511 species living, and the Zygnematophyceae, 4335 living species), Dinoflagellata (2956 living, including the Dinophyceae, 2828 extant), and haptophytes (Haptophyta 1722 species, 517 living).     

Biodiversity: molecular biological domains, symbiosis and kingdom origins.

The number of extant species of organisms is estimated to be from fewer than 3 to more than 30 x 10(6) (May, 1992). Molecular biology, comparative genetics and ultrastructural analyses provide new insights into evolutionary relationships between these species, including increasingly precise ideas of how species and higher taxa have evolved from common ancestors. Accumulation of random mutations and large macromolecular sequence change in all organisms since the Proterozoic Eon has been importantly supplemented by acquisition of inherited genomes ('symbiogenesis'). Karyotypic alterations (polyploidization and karyotypic fissioning) have been added to these other mechanisms of species origin in plants and animals during the Phanerozoic Eon. The new evolution concepts (coupled with current rapid rates of species extinction and ignorance of the extent of biodiversity) prompted this analysis of the field of systematic biology and its role in the reorganization of extant species into higher taxa. Two superkingdoms (= Domains: Prokaryotae and Eukaryotae) and five kingdoms (Monera = Procaryotae or Bacteria; Protoctista: algae, amoebae, ciliates, foraminifera, oomycetes, slime molds, etc.; Mychota: 'true' fungi; Plantae: one phylum (division) of bryophytes and nine phyla of tracheophytes; and Animalia) are recognized. Two subkingdoms comprise the monera: the great diverse lineages are Archaebacteria and Eubacteria. The criteria for classification using molecular, ultrastructural and genetic data for this scheme are mentioned. For the first time since the nineteenth century, logical, technical definitions for each group are given with their time of appearance as inferred from the fossil record in the primary scientific literature. This classification scheme, which most closely reflects the evolutionary history, molecular biology, genetics and ultrastructure of extant life, requires changes in social organization of biologists, many of whom as botanists and zoologists, still behave as if there were only two important kingdoms (plants and animals).     

Phylogenetic position of Dictyostelium inferred from multiple protein data sets

The phylogenetic position of Dictyostelium inferred from 18S rRNA data contradicts that from protein data. Protein trees always show the close affinity of Dictyostelium with animals, fungi, and plants, whereas in 18S rRNA trees the branching of Dictyostelium is placed at a position before the massive radiation of protist groups including the divergence of the three kingdoms. To settle this controversial issue and to determine the correct position of Dictyostelium, we inferred the phylogenetic relationship among Dictyostelium and the three kingdoms Animalia, Fungi, and Plantae by a maximum-likelihood method using 19 different protein data sets. It was shown at the significance level of 1 SE that the branching of Dictyostelium antedates the divergence of Animalia and Fungi, and Plantae is an outgroup of the Animalia-Fungi-Dictyostelium clade.Correspondence to: T. Miyata     

Principles of protein and lipid targeting in secondary symbiogenesis: euglenoid, dinoflagellate, and sporozoan plastid origins and the eukaryote family tree

The biggest unsolved problems in chloroplast evolution are the origins of dinoflagellate and euglenoid chloroplasts,which have envelopes of three membranes not two like plants and chromists, and of the sporozoan plastid, bounded by four smooth membranes. I review evidence that all three of these protozoan plastid types originated by secondary symbiogenesis from eukaryotic symbionts. Instead of separate symbiogenetic events, I argue that dinoflagellate and sporozoan plastids are directly related and that the common ancestor of dinoflagellates and Sporozoa was photosynthetic. I suggest that the last common ancestor of all Alveolata was photosynthetic and acquired its chlorophyll c-containing plastids in the same endosymbiogenetic event as those of Chromista. Chromistaand Alveolata are postulated to be a clade designated chrornalveolates. I propose that euglenoids obtained their plastids from the same(possibly ulvophycean) green alga as chlorarachneans and that Discicristata (Euglenozoa plus Percolozoa) and Cercozoa (the group including chlorarachneans) form a clade designated cabozoa (protozoa with chlorophyll a + b). If both theories are correct, there were only two secondary symbiogenetic events (witnessed by the chlorarachnean and cryptomonad nucleormorphs) in the history of life, not seven as commonly assumed. This greatly reduces the postulated number of independent origins of chloroplast protein-targeting machinery and of gene transfers from endosymbiont to host nuclei. I discuss the membrane and plastid losses and innovations in protein targeting implied by these theories, the comparative evidence for them, and their implications for eukaryote megaphylogeny. The principle of evolutionary conservatism leads to a novel theory for the function of periplastid vesicles in membrane biogenesis ofchlorarachneans and chromists and of the key steps in secondary symbiogenesis. Protozoan classification is also slightly revised by abandoning the probably polyphyletic infrakingdom Actinopoda, grouping Foraminifera and Radiolaria as a new infrakingdom Retaria,placing Heliozoa within a revised infrakingdom Sarcomastigota, establishing a new flagellate phylum Loukozoa for Jakobea plus Anaeromonadea within an emended subkingdom Eozoa, and ranking Archezoa as an infrakingdom within Eozoa.     

Are genetic databases sufficiently populated to detect non-indigenous species?

Correct species identifications are of tremendous importance for invasion ecology, as mistakes could lead to misdirecting limited resources against harmless species or inaction against problematic ones. DNA barcoding is becoming a promising and reliable tool for species identifications, however the efficacy of such molecular taxonomy depends on gene region(s) that provide a unique sequence to differentiate among species and on availability of reference sequences in existing genetic databases. Here, we assembled a list of aquatic and terrestrial non-indigenous species (NIS) and checked two leading genetic databases for corresponding sequences of six genome regions used for DNA barcoding. The genetic databases were checked in 2010, 2012, and 2016. All four aquatic kingdoms (Animalia, Chromista, Plantae and Protozoa) were initially equally represented in the genetic databases, with 64, 65, 69, and 61 % of NIS included, respectively. Sequences for terrestrial NIS were present at rates of 58 and 78 % for Animalia and Plantae, respectively. Six years later, the number of sequences for aquatic NIS increased to 75, 75, 74, and 63 % respectively, while those for terrestrial NIS increased to 74 and 88 % respectively. Genetic databases are marginally better populated with sequences of terrestrial NIS of plants compared to aquatic NIS and terrestrial NIS of animals. The rate at which sequences are added to databases is not equal among taxa. Though some groups of NIS are not detectable at all based on available data—mostly aquatic ones—encouragingly, current availability of sequences of taxa with environmental and/or economic impact is relatively good and continues to increase with time.     

世界蜘蛛的分布格局及其多元相似性聚类分析

蜘蛛是一类种类繁多、数量巨大、分布广泛的捕食性生物。至2012年底,全世界共有蜘蛛43678种（包括亚种）,隶属于112科3898属。科、属、种3个分类阶元的分布域非常悬殊,90%的种分布在一个界内,90%的科是跨界分布或全球分布。按行政区域,亚洲种类较多,欧洲较少,南极洲没有蜘蛛记录;按动物地理区域,古北界和新热带界较多,新北界较少。根据地理条件、生态条件和蜘蛛的分布状况,将全球陆地分为53个基础地理单元,用申效诚等新近提出的相似性通用公式和据此创立的多元相似性聚类分析方法,分别对属、种两级的分布进行分析,得到两个聚类结构相同、聚类关系合理的支序图,而且属级的支序图层次更为分明,在相似性水平为0.32时,53个基础地理单元聚为17个小单元群,在0,22水平上,又聚为8个大单元群。这些大、小单元群的组成单元地域相邻相连,生态条件相对一致,可以作为蜘蛛地理区划的界、亚界两个层级。和华莱士主要以哺乳动物建立的世界动物地理区划相比,主要差异是：1、古北界东、西两部分差异显著,可分设两界;2、新西兰和澳洲大陆相似性较低,可单独设界;3、新几内亚和太平洋岛屿与澳洲大陆的关系远于和东洋界的关系,华莱士线在两界间的作用似乎不存在; 4、新热带界的中美地区似乎属于新北界更为合适,并由此产生了南北美洲间的紧密联系;5、新北界与古北界的相似性关系弱于与新热带界的关系,全北界的概念几近消失。前两点差异可以从地球板块构造的变动得到解释,第3、5个差异已在植物和其它生物类群得到佐证,第4个差异尚不稳定,需要更多类群的比较与分析。使用多元相似性聚类分析方法对于如此典型的点状分布的生物类群和如此海量的数据,能够得到如此精细的,既符合地理学、统计学的逻辑,又符合生物学、生态学逻辑的定量分析结果,这在国内外都是首次成功尝试,其简便性和合理性将会促使在其它类群中的应用。     

Only six kingdoms of life

There are many more phyla of microbes than of macro-organisms, but microbial biodiversity is poorly understood because most microbes are uncultured. Phylogenetic analysis of rDNA sequences cloned after PCR amplification of DNA extracted directly from environmental samples is a powerful way of exploring our degree of ignorance of major groups. As there are only five eukaryotic kingdoms, two claims using such methods for numerous novel 'kingdom-level' lineages among anaerobic eukaryotes would be remarkable, if true. By reanalysing those data with 167 known species (not merely 8-37), I identified relatives for all 8-10 'mysterious' lineages. All probably belong to one of five already recognized phyla (Amoebozoa, Cercozoa, Apusozoa, Myzozoa, Loukozoa) within the basal kingdom Protozoa, mostly in known classes, sometimes even in known orders, families or genera. This strengthens the idea that the ancestral eukaryote was a mitochondrial aerobe. Analogous claims of novel bacterial divisions or kingdoms may reflect the weak resolution and grossly non-clock-like evolution of ribosomal rRNA, not genuine phylum-level biological disparity. Critical interpretation of environmental DNA sequences suggests that our overall picture of microbial biodiversity at phylum or division level is already rather good and comprehensive and that there are no uncharacterized kingdoms of life. However, immense lower-level diversity remains to be mapped, as does the root of the tree of life.     

Molecular phylogeny of the kingdoms Animalia, Plantae, and Fungi

The branching order of the kingdoms Animalia, Plantae, and Fungi has been a controversial issue. Using the transformed distance method and the maximum parsimony method, we investigated this problem by comparing the sequences of several kinds of macromolecules in organisms spanning all three kingdoms. The analysis was based on the large-subunit and small-subunit ribosomal RNAs, 10 isoacceptor transfer RNA families, and six highly conserved proteins. All three sets of sequences support the same phylogenetic tree: plants and animals are sibling kingdoms that have diverged more recently than the fungi. The ribosomal RNA and protein data sets are large enough so that in both cases the inferred phylogeny is statistically significant. The present report appears to be the first to provide statistically conclusive molecular evidence for the phylogeny of the three kingdoms. The determination of this phylogeny will help us to understand the evolution of various molecular, cellular, and developmental characters shared by any two of the three kingdoms. Noting that the large-subunit rRNA sequences have evolved at similar rates in the three kingdoms, we estimated the ratio of the time since the animal-plant split to the time since the fungal divergence to be 0.90.     

Phylogenetic relationship of the kingdoms Animalia, Plantae, and Fungi, inferred from 23 different protein species

The phylogenetic relationship among the kingdoms Animalia, Plantae, and Fungi remains uncertain, because of lack of solid fossil evidence. In spite of the extensive molecular phylogenetic analyses since the early report, this problem is a longstanding controversy; the proposed phylogenetic relationships differ for different authors, depending on the molecules and methods that they use. To settle this problem, we have accumulated 23 different protein species from the three kingdoms and have inferred the phylogenetic trees by three different methods-- the maximum-likelihood method, the neighbor-joining method, and the maximum-parsimony method--for each data set. Although inferred tree topologies differ for different protein species and methods used, both the maximum-likelihood analysis based on the difference (delta l) between the total log-likelihood of a tree and that of the maximum- likelihood tree and bootstrap probability (P) of 23 proteins consisting of 10,051 amino acid sites in total have shown that a tree ((A,F),P), in which Plantae (P) is an outgroup to an Animalia (A)-Fungi (F) clade, is the maximum-likelihood tree; the delta l (= 0.0) and P (94%) of ((A,F),P) are significantly larger than those of ((A,P),F) (delta l = - 54.4 +/- 36.3; and P = 6%) and ((F,P),A) (delta l = -141.1 +/- 30.9; and P = 0%).(ABSTRACT TRUNCATED AT 250 WORDS)      

发光甲虫与生物荧光

生物荧光是活体生物自身可以发光的有趣生命现象。具有这一现象的生物存在于生物四界中,但目前关于这一现象的研究报道主要来自于昆虫,尤其是以萤火虫为代表的发光甲虫的研究。文章对发光甲虫的分类地位、生物荧光发生的原理、发光器官的类型、闪光的“开关”机制、生物荧光的生物学意义及其相关行为学研究进展等进行了详细介绍。此外,还简要提及了荧光生物及其荧光酶的应用。这对了解及探讨生物荧光现象、加强对中国的发光甲虫及其它发光生物的研究及保护利用具有一定的借鉴作用。     

关于卵菌纲分类地位演变的教学体会

随着学科的发展,卵菌纲(Oomycetes)早已从真菌中划分到藻界或茸鞭生物界(Stramenopilia),因此,在真菌学教学中,关于卵菌纲分类地位的变化是一个必须讲解的知识点,同时也是一个较困难的教学点。在这里,就我们授课的内容和体会作一具体介绍,供大家讨论。     

Holothuria triterpene glycosides: a comprehensive guide for their structure elucidation and critical appraisal of reported compounds

Phytochemistry Reviews - Sea cucumbers or holothurians are marine invertebrates, belonging to the phylum Echinodermata (kingdom Animalia). In Asia, they are commonly used as food, while they are...     

Evolutionary relationships of Metazoa within the eukaryotes based on molecular data from Porifera

Recent molecular data provide strong support for the view that all metazoan phyla, including Porifera, are of monophyletic origin. The relationship of Metazoa, including the Porifera, to Plantae, Fungi and unicellular eukaryotes has only rarely been studied by using cDNAs coding for proteins. Sequence data from rDNA suggested a relationship of Porifera to unicellular eukaryotes (choanoflagellates). However, ultrastructural studies of choanocytes did not support these findings. In the present study, we compared amino acid sequences that are found in a variety of metazoans (including sponges) with those of Plantae, Fungi and unicellular eukaryotes, to obtain an answer to this question. We used the four sequences from 70 kDa heat-shock proteins, the serine-threonine kinase domain found in protein kinases, beta-tubulin and calmodulin. The latter two sequences were deduced from cDNAs, isolated from the sponge Geodia cydonium for the phylogenetic analyses presented. These revealed that the sponge molecules were grouped into the same branch as the Metazoa, which is statistically (significantly) separated from those branches that comprise the sequences from Fungi, Plantae and unicellular eukaryotes. From our molecular data it seems evident that the unicellular eukaryotes existed at an earlier stage of evolution, and the Plantae and especially the Fungi and the Metazoa only appeared later.     

Paracercomonas kinetid ultrastructure, origins of the body plan of Cercomonadida, and cytoskeleton evolution in Cercozoa

Serial section reconstruction shows that kinetid ultrastructure in two genetically divergent Paracercomonas (P. virgaria, P. metabolica) is basically similar, differing somewhat from clade A cercomonads. Paracercomonas (Paracercomonadidae fam. n.) have a posterior root (dp1) attached to the posterior centriole, unlike Cercomonadidae (here revised to include only Eocercomonas, Cercomonas, Filomonas gen. n., and Neocercomonas), which belong in clade A (new suborder Cercomonadina) with Cavernomonas (Cavernomonadidae fam. n.). Whether dp1 is serially homologous to anterior root da is unclear. The common ancestor of Cercomonadida probably had five microtubular roots, two fibrillar microtubule-nucleating centres generating microtubular cones, and striated connectors between obtusely angled centrioles. Our new data leave the question of holophyly versus polyphyly of Cercomonadida unresolved, but clarify cercozoan root diversity and homologies. Ventral root vp1 is throughout Cercozoa; vp2 might be restricted to the new superclass Ventrifilosa plus Sarcomonadea. Though cercozoan microtubular arrangements differ substantially from others within the kingdom Chromista, the microtubular root numbering system used for other chromists and Plantae is applicable to them; in doing this we found that the single anterior root of excavates (probably ancestral to Chromista, Plantae and unikonts) and Euglenozoa corresponds with R3 (not R4 as previously thought) of corticate eukaryotes (Chromista plus Plantae).     

A new type of relief condenser for the study of microorganisms

A new type of relief condenser mounted on a current laboratory microscope produced by Lambda Praha was used for the study of microorganisms of two kingdoms, Chromista and Plantae. The pictures obtained by the use of this device had a better resolving power and remarkable contrast, and a well visible 3D effect. Because of the absence of an aperture diaphragm the use was much simpler, compared to relief condensers whose construction was different.