No abstract

Telomeres, ubiquitous and essential structures of eukaryotic chromosomes, are known to come in a variety of forms, but knowledge about their actual diversity and evolution across the whole phylogenetic breadth of the eukaryotic life remains fragmentary. To fill this gap, we employed a complex experimental approach to probe telomeric minisatellites in various phylogenetically diverse groups of algae. Our most remarkable results include the following findings: 1) algae of the streptophyte class Klebsormidiophyceae possess the Chlamydomonas-type telomeric repeat (TTTTAGGG) or, in at least one species, a novel TTTTAGG repeat, indicating an evolutionary transition from the Arabidopsis-type repeat (TTTAGGG) ancestral for Chloroplastida; 2) the Arabidopsis-type repeat is also present in telomeres of Xanthophyceae, in contrast to the presence of the human-type repeat (TTAGGG) in other ochrophytes studied, and of the photosynthetic alveolate Chromera velia, consistent with its phylogenetic position close to apicomplexans and dinoflagellates; 3) glaucophytes and haptophytes exhibit the human-type repeat in their telomeres; and 4) ulvophytes and rhodophytes have unusual telomere structures recalcitrant to standard analysis. To obtain additional details on the distribution of different telomere types in eukaryotes, we performed in silico analyses of genomic data from major eukaryotic lineages, utilizing also genome assemblies from our on-going genome projects for representatives of three hitherto unsampled lineages (jakobids, malawimonads, and goniomonads). These analyses confirm the human-type repeat as the most common and possibly ancestral in eukaryotes, but alternative motifs replaced it along the phylogeny of diverse eukaryotic lineages, some of them several times independently.

A red-pigmented, bacteriochlorophyll (BChl) a-producing strain, AP64T, was isolated previously from the freshwater Swan Lake located in the western Gobi Desert. Based on its 16S rRNA gene sequence identity (96.1 %) to the type strain Gemmatimonas aurantiaca T-27T, the new isolate was tentatively classified as a member of the bacterial phylum Gemmatimonadetes. Here, we report its formal description and polyphasic characterization. Strain AP64T grew best on agar media under 9.8–15.2 % atmospheric oxygen. The cells were rods, dividing by symmetrical or asymmetrical binary fission. Budding structures were also observed. Its genomic DNA G+C content was 64.4 % (from the draft genome sequence). Phylogenetic analysis based on the 16S rRNA gene sequence clearly separated AP64T from related species. Its genotypic differentiation from phylogenetically close relatives was further supported by performing in silico DNA–DNA hybridization and calculating average nucleotide identity, whereas the high percentage (67.3 %) of shared conserved proteins between strain AP64T and Gemmatimonas aurantiaca T-27T supports the classification of the two strains into the same genus. Strain AP64T contained C16 : 1, C14 : 1 and C18 : 1ω9c as predominant fatty acids. The main respiratory quinone was menaquinone 8 (MK-8). The most distinctive feature of strain AP64T was the presence of fully functional purple bacterial photosynthetic reaction centres. The main CO2-fixation pathways were absent. Strain AP64T was capable of growth and BChl production in constant darkness. Thus, strain AP64T is a facultatively photoheterotrophic organism. It represents a novel species of the genus Gemmatimonas, for which the name Gemmatimonas phototrophica sp. nov. is proposed. The type strain is AP64T ( = DSM 29774T = MCCC 1K00454T). Emended descriptions of the genus Gemmatimonas and Gemmatimonas aurantiaca are also provided.

Red algae represent an evolutionarily important group that gave rise to the whole red clade of photosynthetic organisms. They contain a unique combination of light-harvesting systems represented by a membrane-bound antenna and by phycobilisomes situated on thylakoid membrane surfaces. So far, very little has been revealed about the mobility of their phycobilisomes and the regulation of their light-harvesting system in general. Therefore, we carried out a detailed analysis of phycobilisome dynamics in several red alga strains and compared these results with the presence (or absence) of photoprotective mechanisms. Our data conclusively prove phycobilisome mobility in two model mesophilic red alga strains, Porphyridium cruentum and Rhodella violacea. In contrast, there was almost no phycobilisome mobility in the thermophilic red alga Cyanidium caldarium that was not caused by a decrease in lipid desaturation in this extremophile. Experimental data attributed this immobility to the strong phycobilisomephotosystem interaction that highly restricted phycobilisome movement. Variations in phycobilisome mobility reflect the different ways in which light-harvesting antennae can be regulated in mesophilic and thermophilic red algae. Fluorescence changes attributed in cyanobacteria to state transitions were observed only in mesophilic P. cruentum with mobile phycobilisomes, and they were absent in the extremophilic C. caldarium with immobile phycobilisomes. We suggest that state transitions have an important regulatory function in mesophilic red algae; however, in thermophilic red algae, this process is replaced by nonphotochemical quenching.

Members of the morphologically unusual cyanobacterial family Gomontiellaceae were studied using a polyphasic approach. Cultured strains of Hormoscilla pringsheimii, Starria zimbabweënsis, Crinalium magnum, and Crinalium epipsammum were thoroughly examined, and the type specimen of the family, Gomontiella subtubulosa, was investigated. The results of morphological observations using both light microscopy and transmission electron microscopy were consistent with previous reports and provided evidence for the unique morphological and ultrastructural traits of this family. Analysis of the 16S rRNA gene confirmed the monophyletic origin of non-marine repre-sentatives of genera traditionally classified into this family. The family was phylogenetically placed among other groups of filamentous cyanobacterial taxa. The presence of cellulose in the cell wall was analyzed and confirmed in all cultured Gomontiellaceae members using Fourier transform infrared spectroscopy and fluorescence microscopy. Evaluation of toxins produced by the studied strains revealed the hepatotoxin cylindrospermopsin (CYN) in available strains of the genus Hormoscilla. Production of this compound in both Hormoscilla strains was detected using high-performance liquid chromatography in tandem with high resolution mass spectrometry and confirmed by positive PCR amplification of the cyrJ gene from the CYN biosynthetic cluster. To our knowledge, this is the first report of CYN production by soil cyanobacteria, establishing a previously unreported CYN-producing lineage. This study indicates that cyanobacteria of the family Gomontiellaceae form a separate but coherent cluster defined by numerous intriguing morphological, ultrastructural, and biochemical features, and exhibiting a toxic potential worthy of further investigation.

Oxadiazines are heterocyclic compounds containing N-N-O or N-N-C-O system within a six membered ring. These structures have been up to now exclusively prepared via organic synthesis. Here, we report the discovery of a natural oxadiazine nocuolin A (NoA) that has a unique structure based on 1,2,3-oxadiazine. We have identified this compound in three independent cyanobacterial strains of genera Nostoc, Nodularia, and Anabaena and recognized the putative gene clusters for NoA biosynthesis in their genomes. Its structure was characterized using a combination of NMR, HRMS and FTIR methods. The compound was first isolated as a positive hit during screening for apoptotic inducers in crude cyanobacterial extracts. We demonstrated that NoA-induced cell death has attributes of caspase-dependent apoptosis. Moreover, NoA exhibits a potent anti-proliferative activity (0.7–4.5 μM) against several human cancer lines, with p53-mutated cell lines being even more sensitive. Since cancers bearing p53 mutations are resistant to several conventional anti-cancer drugs, NoA may offer a new scaffold for the development of drugs that have the potential to target tumor cells independent of their p53 status. As no analogous type of compound was previously described in the nature, NoA establishes a novel class of bioactive secondary metabolites.

Introduction: Augmentation cystoplasty is an effective approach to the detrusor hyperreflexia which is refractory to conservative treatment. Sporadic data have been published in patients with progressive diseases such as multiple sclerosis (MS). Materials and Methods: Augmentation ileocystoplasty (Goodwin ‘cup-patch’) was performed in 9 patients (7 females, 2 males). The average Expanded Disability Status Scale score was 4.1 (range 3.0–6.5); 7 patients had relapse-remitting MS and 2 patients secondary-progressive MS. The indication was a detrusor hyperreflexia refractory to conservative treatment in 8 patients and a detrusor hyperrefluxia with third degree bilateral vesico-ureteral reflux and renal insufficiency in 1 patient. Pre- and postoperative objective parameters were evaluated by urodynamic examination, imaging methods and laboratory examination. Subjective evaluation was performed using a questionnaire on micturition symptoms (score 0–5) and on quality of life (score 0–6). Results: With a follow-up of 6–19 months, we recorded an average increase of the maximum detrusor capacity from 105 to 797 ml and decrease of maximum detrusor pressure from 53 to 30 cm H₂O. Postmicturition residual urine >25% of the maximum capacity was present in 6 patients who performed clear intermittent autocatheterization postoperatively (2 patients preoperatively). In all patients there was a significant improvement in the irritation micturition symptomatology (pollakisuria, nycturia, urgency and urge incontinence) and the quality of life score improved on average from 5 to 0.7. In the case of the patient with renal insufficiency, the creatinine level decreased from 286 to 150 µmol/l; in the other patients renal function remained normal. Conclusions: Augmentation cystoplasty is a safe and effective method for indicated patients, which significantly enhances their quality of life.

The oceanic unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501 exhibits large diel changes in abundance of both Photosystem II (PSII) and Photosystem I (PSI). To understand the mechanisms underlying these dynamics, we assessed photosynthetic parameters, photosystem abundance and composition, and chlorophyll-protein biosynthesis over a diel cycle. Our data show that the decline in PSII activity and abundance observed during the dark period was related to a light-induced modification of PSII, which, in combination with the suppressed synthesis of membrane proteins, resulted in monomerization and gradual disassembly of a large portion of PSII core complexes. In the remaining population of assembled PSII monomeric complexes, we detected the non-functional version of the D1 protein, rD1, which was absent in PSII during the light phase. During the dark period, we also observed a significant decoupling of phycobilisomes from PSII and a decline in the chlorophyll a quota, which matched the complete loss of functional PSIIs and a substantial decrease in PSI abundance. However, the remaining PSI complexes maintained their photochemical activity. Thus, during the nocturnal period of nitrogen fixation C. watsonii operates a suite of regulatory mechanisms for efficient utilization/recycling of cellular resources and protection of the nitrogenase enzyme.