Systematically they fall within the division Charophyta/Streptophyta, in which the land plants (Embryophyta) emerged.[2]. Sexual reproduction in Zygnematales takes place through a process called conjugation.[3] Here filaments of opposite gender line up, and tubes form between corresponding cells. The male cells then become amoeboid and crawl across, or sometimes both cells crawl into the tube. The cells then meet and fuse to form a zygote, which later undergoes meiosis to produce new filaments. As in plants, only the female passes chloroplasts on to the offspring.[citation needed]. Other conjugating algae are the Mesotaeniaceae, sister of the Zygnematales, and spirotaenia, a basal green algae. Additionally, the Desmidiales appear to have emerged deep within the Zygnematales, and are also conjugating.[4]. ...

The conjugating green algae are among the most common algae in freshwater streams, ponds, and lakes. Including such familiar algae as Spirogyra, these algae, unlike most other green algae, lack flagellated cells at any time during the life cycle. They reproduce sexually through several variations of the process known as conjugation, in which haploid vegetative cells come close together and form nonflagellated gametes that fuse to form a zygote. Meiosis occurs in the zygote and from one to four offspring emerge at germination. The thalli (the bodies of the algae) are of various types, including single cells, filaments or chains of cells, and colonies. These algae have been observed by microscopists for over a century, for scientific interest and intrinsic beauty. There are approximately 56 genera in five families within this group. Families of the Zygnematales are distinguished by differences in the structure of wall of the vegetative cell. The Zygnemataceae and Mesotaeniaceae have smooth, ...

Previous studies of the phylogeny of Streptophyta were restricted mainly to ribosomal RNA or sequences of organellar origin [24-27]. We now, used for the first time, large data sets of nuclear-encoded proteins for phylogenetic studies in this important evolutionary lineage. Our phylogenetic analyses are in agreement with both phylogenies obtained using a data set of concatenated plastid proteins or ribosomal RNAs [26, 27], but are in conflict with the 4 gene tree mentioned above [24]. In contrast, Coleochaete was found to be sister to embryophytes [40] in a recent analysis based on 77 nuclear encoded ribosomal proteins (12,459 amino acid positions). However, as this study failed to recover the monophyly of the Coleochaetales (placing Chaetosphaeridium within the Zygnematales) the conclusions from this study should be treated with caution. In the 4 gene analysis the topology (Zygnematales, (Coleochaetales, (Charales, embryophytes))) was observed. This analysis suggested that the streptophyte ...

en] The cloning and expression of genes from a psychrotrophic bacterium in a mesophilic host are described. Three lipase (Lip)-encoding genes (lip) from the antarctic psychrotroph, Moraxella TA144, were cloned by inserting Sau3AI-generated DNA fragments into the BamHI site of the pSP73 plasmid vector. To prevent heat denaturation of the gene product, the screening procedure on agar plates containing an emulsified lipid involved growing of Escherichia coli recombinant colonies at 25 degrees C followed by incubation at 0 degree C. The three recombinant (reLip) were cell-associated and differed by their respective specificity towards p-nitrophenyl esters of various aliphatic chain lengths. These cloned reLip conserved the main character of the wild-type enzymes, i.e. a dramatic shift of the optimal temperature of activity towards low temperatures and pronounced heat lability ...

Rabeling C, Brown JM & Verhaagh M (2008). Newly discovered sister lineage sheds light on early ant evolution. PNAS 105 (39): 14913-7. DOI:10.1073/pnas.0806187105. PMID 18794530 ...

Brook, A.J. & Williamson, D.B. (2010). A monograph on some British desmids. Order Zygnematales Suborder Zygonemoidiineae Family Zygnemataceae Subfamily Mesotaenioideae (Saccoderm desmids) and Suborder Closteriineae Family Peniaceae and Family Closteriaceae. Edited by J.H. Price & N.J. Evans. pp. [i-ii], iii-v [1-5], 6-364, 157 pls. London: The Ray Society.. Brook, A.J., Williamson, D.B. & John, D.M. (2011). Phylum Chlorophyta. Family Mesotaeniaceae (saccoderm desmids). In: The freshwater algal flora of the British Isles. An identification guide to freshwater and terrestrial algae. Second edition. (John, D.M., Whitton, B.A. & Brook, A.J. Eds), pp. 609-616. Cambridge: Cambridge University Press.. Coesel, P.F.M. & Meesters, K.[J.] (2007). Desmids of the Lowlands Mesotaeniaceae and Desmidaceae of the European Lowlands. pp. [1]-351, 20 text-figs, 123 pls. Zeist: KNNV Publishing.. Das, D. & Keshri, J.P. (2013). Desmids of Khechiperi Lake, Sikkim Eastern Himalaya. Algological Studies/Archiv für ...

The 16S rRNAs of nine new species of prokaryotes, that had been isolated from four lakes of the Vestfold Hills, have been sequenced. These sequences were compared with those of their closest taxonomic relatives available from publicly available databases. The Antarctic species were of wide diversity with representatives from the domains Archaea and Bacteria (sensu Woese). Generally, they were most closely related to organisms from marine environments. The sequence dissimilarity between the rRNA sequences of the Antarctic strains and their nearest known relatives suggest they diverged from each other much earlier than the establishment of their modern Antarctic habitat. The conserved nature of the 16S rRNA molecule suggests it may not be as useful for detecting evolutionary change in Antarctic prokaryotes as distinct from non-Antarctic prokaryotes. Although the optimal temperature for growth of each species is well above the temperature of its environment, each has a reduced optimal temperature ...

Analyses of morphological and ultrastructural characters, and also of the information carried by gene sequences have established that green algae belonging to the class Charophyceae gave rise to the more than 500,000 land plant species currently inhabiting our planet [1, 2]. Charophycean green algae and land plants form the green plant lineage Streptophyta [3], whereas most, if not all, of the other extant green algae belong to the sister lineage Chlorophyta [2]. In contrast to the large diversity of land plants, only a few thousands charophycean species are living today. Six monophyletic groups are currently recognized in the Charophyceae: the Mesostigmatales [4] represented by Mesostigma viride, a scaly biflagellate that has long been thought to be a member of the Prasinophyceae (the earliest-diverging lineage of the Chlorophyta) [5]; the Chlorokybales represented as well by a single species (Chlorokybus atmophyticus); the Klebsormidiales (3 genera, 45 spp.); the Zygnematales (~ 50 genera, ~ ...

In the case of the partly homoplasious data, the median-joining network reconstructs a synapomorphy of the clade BC, because A is not placed on the node. This is because one character in our matrix is a methodologically undetectable parallelism - the same trait evolved in the sister taxa B and C, but only after both evolved from A. Clade BC is non-inclusive (paraphyletic), since A is the direct ancestor of both B and C and the clade BC lacks a real synapomorphy (if we go back to Hennigs concept). The reconstructed A would, however, be a stem taxon and clade BC would be inclusive (monophyletic) with one (inferred) synapomorphy. But this is a purely semantic problem of cladistics. In the real world, we will hardly have the data to discern whether A represents: the last common ancestor of B and C, a stem taxon of the ABC-lineage (a), a very early precursor of B or C (b/c), or an ancient sister lineage of A, B, and/or C (a*). For practicality, one would eventually include all fossil forms with ...

Acontias is a genus of limbless skinks, the lance skinks, (family Scincidae) in the African subfamily Acontinae. Most are small animals, but the largest member of the genus is Acontias plumbeus at approximately 40 cm (16 in) snout-vent length. All members of this genus are live-bearing, sandswimmers, with fused eyelids. A recent review moved species that were formerly placed in the genera Typhlosaurus, Acontophiops, and Microacontias into this genus, as together these form a single branch in the tree of life. This new concept of Acontias is a sister lineage to Typhlosaurus, and these two genera are the only genera within the subfamily Acontinae. These 21 species are recognized: Acontias aurantiacus (W. Peters, 1854) Acontias bicolor (Hewitt, 1929) Acontias breviceps Essex, 1925 - shorthead lance skink Acontias cregoi (Boulenger, 1903) Acontias gariepensis (V. FitzSimons, 1941) Acontias gracilicauda Essex, 1925 Acontias jappi (Broadley, 1968) Acontias kgalagadi (Lamb, Biswas & Bauer, 2010) ...

Classical biology has also saddled us with the phylogenetic tree, an image the biologist invests with a deep and totally unwarranted significance. The tree is no more than a representational device, but to the biologist it is some God-given truth. Thus, for example, we agonize over how the tree can accommodate horizontal gene transfer events, when it should simply be a matter of when (and to what extent) the evolution course can be usefully represented by a tree diagram. Evolution defines the tree, not the reverse. Tree imagery has locked the biologist into a restricted way of looking at ancestors. It is the tree image, almost certainly, that has caused us to turn Darwins conjecture that all organisms might have descended from a simple primordial form into doctrine: the doctrine of common descent. As we shall discuss below, it is also the tree image that has caused biologists (incorrectly) to take the archaea and the eukaryotes to be sister lineages. Much of the current discussion/debate ...

Classical biology has also saddled us with the phylogenetic tree, an image the biologist invests with a deep and totally unwarranted significance. The tree is no more than a representational device, but to the biologist it is some God-given truth. Thus, for example, we agonize over how the tree can accommodate horizontal gene transfer events, when it should simply be a matter of when (and to what extent) the evolution course can be usefully represented by a tree diagram. Evolution defines the tree, not the reverse. Tree imagery has locked the biologist into a restricted way of looking at ancestors. It is the tree image, almost certainly, that has caused us to turn Darwins conjecture that all organisms might have descended from a simple primordial form into doctrine: the doctrine of common descent. As we shall discuss below, it is also the tree image that has caused biologists (incorrectly) to take the archaea and the eukaryotes to be sister lineages. Much of the current discussion/debate ...

Classical biology has also saddled us with the phylogenetic tree, an image the biologist invests with a deep and totally unwarranted significance. The tree is no more than a representational device, but to the biologist it is some God-given truth. Thus, for example, we agonize over how the tree can accommodate horizontal gene transfer events, when it should simply be a matter of when (and to what extent) the evolution course can be usefully represented by a tree diagram. Evolution defines the tree, not the reverse. Tree imagery has locked the biologist into a restricted way of looking at ancestors. It is the tree image, almost certainly, that has caused us to turn Darwins conjecture that all organisms might have descended from a simple primordial form into doctrine: the doctrine of common descent. As we shall discuss below, it is also the tree image that has caused biologists (incorrectly) to take the archaea and the eukaryotes to be sister lineages. Much of the current discussion/debate ...

Fornicata are traditionally classified into Diplomonadida, Retortamonadida, Carpediemonas, and Dysnectes. Diplomonadida and Retortamonadida have been regarded as closely related and together they constitute the taxon Eopharyngia (the term refers to the extensively developed cytopharynx of diplomonads and retortamonads). The hypothesis of Eopharyngia was supported by molecular-phylogenetic studies which included sequences of Retortamonas and several diplomonad genera. At first, the studies based on the SSU rRNA gene (Silberman et al. 2002; Kolisko et al. 2005; Keeling and Brugerolle 2006) indicated that diplomonads may not be monophyletic and that Retortamonas may be sister to the Giardiinae diplomonad lineage. However, the analysis based on the hsp90 gene showed that diplomonads are monophyletic and that Retortamonas forms their sister lineage, which was consistent with previous morphology-based hypotheses. Sequence data of the second retortamonads genus, Chilomastix, have been obtained quite ...

Ahmed, Z.U., Begum, Z.N.T., Hassan, M.A., Khondker, M., Kabir, S.M.H., Ahmad, M., Ahmad, A.T.A., Rahman, A.K.A. & Haque, E.U. [Eds] (2008). Volume 3 Algae Chlorophyta (Aphanochaetaceae-Zygnemataceae). In: Encyclopedia of flora and fauna of Bangladesh. pp. [1]-812, 146 col. figs. Dhaka: Asiatic Society of Bangladesh.. Created: 13 April 2017 by M.D. Guiry. Verified by: 13 April 2017 by M.D. Guiry. Accesses: This record has been accessed by users 512 times since it was created.. Verification of data ...

Author Summary In 2002, the publication of the genome of Plasmodium falciparum, the most malignant agent of malaria, generated hopes in the fight against this deadly disease by the opportunities it offered to discover new drug targets. Since then results have not lived up to the expectations. The development of comparative genomics to further understanding of P. falciparum has indeed been hindered by a lack of knowledge of closely related species genomes. Only one species, P. reichenowi, infecting chimpanzees, was hitherto known as a sister lineage of P. falciparum. Here we describe a new Plasmodium species infecting chimpanzees in Africa. Based on its whole mitochondrial genome, we demonstrate that this species is a relative of P. falciparum and P. reichenowi. The analysis of its genome should thus offer the opportunity to explore P. falciparum specific adaptations to humans. Our results bring new elements to the debate surrounding the origin of this lineage. They suggest that it may have been present

Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial