Common evolutionary origin of planktonic and benthic nitrogen-fixing oscillatoriacean cyanobacteria from tropical oceans

The filamentous cyanobacteria belonging to the genus Hydrocoleum (Blennothrix) are among the most common mat-forming cyanobacteria in tropical oceans. We present here the evidence that these benthic cyanobacteria are morphologically and phylogenetically very close to the planktonic species of Trichodesmium. Genetic relationship was established independently with regard to sequences of the 16S rRNA gene, nifH gene, and phycocyanin and phycoerythrin intergenic spacers. The species of both genera formed a common distinct branch in phylogenetically reconstructed cyanobacterial trees, suggesting that the main constituents of cyanobacterial benthos and plankton have an early common origin and both represent major contributors to nitrogen budget of tropical oceans today as in the distant geological past

Five-year study assessing the clinical utility of anti-Müllerian hormone measurements in reproductive-age women with cancer

An important discussion point before chemotherapy is ovarian toxicity, a side-effect that profoundly affects young women with cancer. Their quality of life after successful treatment, including the ability to conceive, is a major concern. We asked whether serum anti-Müllerian hormone (AMH) measurements before chemotherapy for two most common malignancies are predictive of long-term changes in ovarian reserve? A prospective cohort study measured serum AMH in 66 young women with lymphoma and breast cancer, before and at 1 year and 5 years after chemotherapy, compared with 124 healthy volunteers of the same age range (18-43 years). Contemporaneously, patients reported their menses and live births during 5-year follow-up. After adjustment for age, serum AMH was 1.4 times higher (95% CI 1.1 to 1.9; P < 0.02) in healthy volunteers than in cancer patients before chemotherapy. A strong correlation was observed between baseline and 5-year AMH in the breast cancer group (P < 0.001, regression coefficient = 0.58, 95% CI 0.29 to 0.89). No significant association was found between presence of menses at 5 years and serum AMH at baseline (likelihood ratio test from logistics regression analysis). Reproductive-age women with malignancy have lower serum AMH than healthy controls even before starting chemotherapy. Pre-chemotherapy AMH was significantly associated with long-term ovarian function in women with breast cancer. At key time points, AMH measurements could be used as a reproductive health advisory tool for young women with cancer. Our results highlight the unsuitability of return of menstruation as a clinical indicator of ovarian reserve after chemotherapy. [Abstract copyright: Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.

Phytoplankton responses to marine climate change – an introduction

Phytoplankton are one of the key players in the ocean and contribute approximately 50% to global primary production. They serve as the basis for marine food webs, drive chemical composition of the global atmosphere and thereby climate. Seasonal environmental changes and nutrient availability naturally influence phytoplankton species composition. Since the industrial era, anthropogenic climatic influences have increased noticeably – also within the ocean. Our changing climate, however, affects the composition of phytoplankton species composition on a long-term basis and requires the organisms to adapt to this changing environment, influencing micronutrient bioavailability and other biogeochemical parameters. At the same time, phytoplankton themselves can influence the climate with their responses to environmental changes. Due to its key role, phytoplankton has been of interest in marine sciences for quite some time and there are several methodical approaches implemented in oceanographic sciences. There are ongoing attempts to improve predictions and to close gaps in the understanding of this sensitive ecological system and its responses

Heterotrophic bacteria from brackish water of the Southern Baltic Sea: biochemical and molecular identification and characterisation

Six bacterial strains isolated from the surface water of the southern Baltic Sea were described on the basis of their morphological, physiological and biochemical features, and were classified on the basis of 16S rDNA sequence analysis. Comparative analyses of the 16S rDNA sequences of five of the six bacterial strains examined displayed a ≥98% similarity to the sequences available in the NCBI GenBank. The 16S rDNA sequence of strain 2 shared only a 96% similarity with other published sequences, which suggests that this is a new, hitherto unknown species. The isolated heterotrophic bacteria belong to the families Bacillaceae (strain 1), Flexibacteriaceae (strain 2), Sphingomonadaceae (strains 3, 5), Micrococcaceae (strain 4) and Aurantimonadaceae (strain 6). This is the first study in which the polyphasic approach has been applied to the identification of heterotrophic bacteria from the brackish waters of the Gulf of Gdańsk and Gdańsk Deep

Microbial mats associated with bryozoans (Coorong Lagoon, South Australia)

Bryostromatolites are laminated carbonate rocks composed of bryozoan zoarial laminae. The laminated texture is frequently caused by patterns of bryozoan self over-growth as a regular defensive tactic against microbial fouling. In the Coorong Lagoon (South Australia), another type of bryostromatolite is present where the laminated growth of the weakly calcifying bryozoan species Conopeum aciculata is postmortally stabilized by cyanobacterial mats at the surface, and fungal mats settling in the zooecial cavities. A tough extracellular slime network produced by benthic cyanobacteria is a trap for sediment particles, provides a method of adhesion to the bryozoan substrate, and produces a biological lamination by the vertical stratification of dead bryozoan skeletons. These slimes are also important for the preservation of cell structures and for their fossilization. Seasonal fluctuations in salinity and water level are the most important regional control factors, causing a phase displacement in the growth optima of microbial mats and bryozoans, thereby resulting in a rigid bryostromatolitic fabric.Katarzyna Palinska, Joachim Scholz, Katja Sterflinger, Gisela Gerdes, Yvonne Bon

Microbial communities in Messinian evaporite deposits of the Vena del Gesso (northern Apennines, Italy).

The Vena del Gesso (Northern Apennines) is a 230 m-thick succession consisting of up to 16 gypsum-shale cycles belongingto the \u201cLower Evaporites\u201d formed during the Messinian salinity crisis in theMediterranean. The study of the microbial communitiespreserved in the gypsum crystals of one complete cycle (6th cycle at Monte Tondo quarry) showed abundant, regularly arranged filamentous forms that resemble morphologically modern obligate phototrophes, cyanobacteria colonizing modern photic, shallow-water gypsum basins.At least four different bacterial populations have been recognized:a) filamentous type cyanobacteria with characteristic inserted funnel shaped structure resembling the modern Scytonematacean;b) Type 1 organisms consisting of filamentous structures impregnated by clay minerals containing pyrite grains in the outer sheath;c) Type 2 filaments filled by clay minerals with dolomite in the outer sheath;d) Type 3 filamentous organisms with a central hollow tube and an encrusted outer sheath mainly composed of calcium carbonate.These organisms were probably associated with other heterotrophic bacteria as suggested by the presence of dolomite and pyrite structures.The size and preservation suggest that most of these cyanobacteria were likely conducting oxygenic photosynthesis as presently observed in modern solar salt works. It follows that they were living in shallow water settings or settled down from the water column to the bottom of a relatively deep evaporite basin

Opportunistic cyanobacteria in benthic microbial mats of a tropical lagoon, Tikehau Atoll, Tuamotu Archipelago : minor in natural populations, major in cultures

Studies in microbial ecology focus on identifying field dominant microbial populations using culture independent tools, whereas minor populations are often ignored. We characterized the cyanobacterial populations from the Tikehau Atoll lagoon, Tuamotu Archipelago, which responded to standard culturing media. The cultivation approach recruited cryptic cyanobacterial taxa, which were not observed in the studied mats, as revealed by microscopic comparison. Twelve strains belonging to the unicellular genera (Aphanothece NAGELI, Chlorogloea WILLE and Cyanocystis BORZI) and the filamentous cyanobacteria with narrow filaments (Leptolyngbya ANAGNOSTIDIS et KOMAREK, Phormidium KUZING ex GOMONT and Pseudanabaena LAUTERBORN) dominated the cultures. The genera Cyanocystis and Chlorogloea were genotypically characterized for the first time. Four strains assigned to Phormidium showed 100% identity using 16S rRNA sequences but additional gene analyses as well as phenotypic distinctions suggest finer differentiation within this group. Eight cyanobacterial strains out of twelve fixed dinitrogen with rates ranging from 3.3 up to 15.8 nmoles N-2 mu g(-1) Chl-a h(-1) and their nitrogen fixation ability was further confirmed by molecular detection of nifH gene. Nine strains possessed phycoerythrin, and two performed complementary chromatic adaptation. The present study documented the existence of an autochthonous subdominant cyanobacterial assemblage with variable physiological features that may enable them to replace dominant species in the microbial mats of Tikehau Atoll lagoon. These minor populations may be ecologically important, particularily in case of environmental disturbances