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1.
Extremophiles ; 23(1): 35-48, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30284641

RESUMO

Genotypic and morphological diversity of cyanobacteria in the Rupite hot spring (Bulgaria) was investigated by means of optical microscopy, cultivation, single-cell PCR, and 16S rRNA gene amplicon sequencing. Altogether, 34 sites were investigated along the 71-39 °C temperature gradient. Analysis of samples from eight representative sites shown that Illumina, optical microscopy, and Roche 454 identified 72, 45 and 19% respective occurrences of all cumulatively present taxa. Optical microscopy failed to detect species of minor occurrence; whereas, amplicon sequencing technologies suffered from failed primer annealing and the presence of species with extensive extracellular polysaccharides production. Amplicon sequencing of the 16S rRNA gene V5-V6 region performed by Illumina identified the cyanobacteria most reliably to the generic level. Nevertheless, only the combined use of optical microscopy, cultivation and sequencing methods allowed for reliable estimate of the cyanobacterial diversity. Here, we show that Rupite hot-spring system hosts one of the richest cyanobacterial flora reported from a single site above 50 °C. Chlorogloeopsis sp. was the most abundant at the highest temperature (68 °C), followed by Leptolyngbya boryana, Thermoleptolyngbya albertanoae, Synechococcus bigranulatus, Oculatella sp., and Desertifilum sp. thriving above 60 °C, while Leptolyngbya geysericola, Geitlerinema splendidum, and Cyanobacterium aponinum were found above 50 °C.


Assuntos
Cianobactérias/genética , Fontes Termais/microbiologia , Microbiota , Cianobactérias/classificação , Cianobactérias/citologia , Cianobactérias/isolamento & purificação , RNA Ribossômico 16S/genética
2.
J Appl Phycol ; 30(3): 1859-1874, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29899600

RESUMO

Marine biofouling is a paramount phenomenon in the marine environment and causes serious problems to maritime industries worldwide. Marine algae are known to produce a wide variety of chemical compounds with antibacterial, antifungal, antialgal, and anti-macrofouling properties, inhibiting the settlement and growth of other marine fouling organisms. Significant investigations and progress have been made in this field in the last two decades and several antifouling extracts and compounds have been isolated from micro- and macroalgae. In this minireview, we have summarized and evaluated antifouling compounds isolated and identified from macroalgae and microalgae between January 2010 and June 2016. Future directions for their commercialization through metabolic engineering and industrial scale up have been discussed. Upon comparing biogeographical regions, investigations from Southeast Asian waters were found to be rather scarce. Thus, we have also discussed the need to conduct more chemical ecology based research in relatively less explored areas with high algal biodiversity like Southeast Asia.

3.
J Appl Phycol ; 30(3): 1875, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-31186603

RESUMO

[This corrects the article DOI: 10.1007/s10811-017-1322-0.].

4.
Protist ; 168(4): 468-480, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28822911

RESUMO

Phytomyxea are obligate endoparasites of angiosperm plants and Stramenopiles characterised by a complex life cycle. Here Maullinia braseltonii sp. nov., an obligate parasite infecting the bull kelp Durvillaea (Phaeophyceae, Fucales) from the South-Eastern Pacific (Central Chile and Chiloe Island) and South-Western Atlantic (Falkland Islands, UK) is described. M. braseltonii causes distinct hypertrophies (galls) on the host thalli making it easily identifiable in the field. Sequence comparisons based on the partial 18S and the partial 18S-5.8S-28S regions confirmed its placement within the order Phagomyxida (Phytomyxea, Rhizaria), as a sister species of the marine parasite Maullinia ectocarpii, which is also a parasite of brown algae. The development of resting spores in M. braseltonii is described by light and electron microscopy and confirmed by FISH experiments, which visually showed the differential expression of the 28S non-coding gene, strongly in early plasmodia and weakly in late cysts. M. braseltonii is, so far, the only phytomyxean parasite of brown algae for which the formation of resting spores has been reported, and which is widely distributed in Durvillaea stocks from the Southeastern Pacific and Southwestern Atlantic.


Assuntos
Kelp/parasitologia , RNA de Algas/genética , Rhizaria/classificação , Rhizaria/fisiologia , Chile , Ilhas Malvinas , Filogenia , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , RNA Ribossômico 5,8S/genética , Rhizaria/genética , Análise de Sequência de RNA
5.
Front Microbiol ; 6: 2, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25674079

RESUMO

Lanthanides are biologically non-essential elements with wide applications in technology and industry. Their concentration as environmental contaminants is, therefore, increasing. Although non-essential, lanthanides have been proposed (and even used) to produce beneficial effects in plants, even though their mechanisms of action are unclear. Recently, it was suggested that they may replace essential elements. We tested the effect of low concentrations of lanthanides on the common freshwater microalga Desmodesmus quadricauda, grown under conditions of metal ion-deficiency (lower calcium or manganese concentrations). Our goal was to test if lanthanides can replace essential metals in their functions. Physiological stress was recorded by studying growth and photosynthetic activity using a pulse amplitude modulation (PAM) fluorimeter. We found that nutrient stress reduced parameters of growth and photosynthesis, such as maximal quantum yield, relative electron transport rate, photon capturing efficiency and light saturation irradiance. After adding low concentrations of five lanthanides, we confirmed that they can produce a stimulatory effect on microalgae, depending on the nutrient (metal) deprivation. In the case of a calcium deficit, the addition of lanthanides partly alleviated the adverse effects, probably by a partial substitution of the element. In contrast, with manganese deprivation (and at even lower concentrations), lanthanides enhanced the deleterious effect on cellular growth and photosynthetic competence. These results show that lanthanides can replace essential elements, but their effects on microalgae depend on stress and the nutritional state of the microalgae, raising the possibility of environmental impacts at even low concentrations.

6.
PLoS One ; 7(9): e45358, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23028958

RESUMO

Durvillaea antarctica (Fucales, Phaeophyceae) is a large kelp of high ecological and economic significance in the Southern Hemisphere. In natural beds along the central coast of Chile (Pacific Ocean), abnormal growth characterized by evident gall development and discolorations of the fronds/thallus was observed. Analysing these galls by light microscopy and scanning electron microscopy revealed the presence of endophytic eukaryotes showing typical characteristics for phytomyxean parasites. The parasite developed within enlarged cells of the subcortical tissue of the host. Multinucleate plasmodia developed into many, single resting spores. The affiliation of this parasite to the Phytomyxea (Rhizaria) was supported by 18S rDNA data, placing it within the Phagomyxida. Similar microorganisms were already reported once 23 years ago, indicating that these parasites are persistent and widespread in D. antarctica beds for long times. The symptoms caused by this parasite are discussed along with the ecological and economic consequences. Phytomyxean parasites may play an important role in the marine ecosystem, but they remain understudied in this environment. Our results demonstrate for the first time the presence of resting spores in Phagomyxida, an order in which resting spores were thought to be absent making this the first record of a phagomyxean parasite with a complete life cycle so far, challenging the existing taxonomic concepts within the Phytomyxea. The importance of the here described resting spores for the survival and ecology of the phagomyxid parasite will be discussed together with the impact this parasite may have on 'the strongest seaweed of the world', which is an important habitat forming and economic resource from the Southern Hemisphere.


Assuntos
Kelp/parasitologia , Feófitas/parasitologia , Plasmodioforídeos/patogenicidade , Chile , DNA Ribossômico/genética , Ecologia , Kelp/ultraestrutura , Microscopia de Força Atômica , Feófitas/ultraestrutura , Filogenia , Plasmodioforídeos/classificação , Plasmodioforídeos/genética , Reação em Cadeia da Polimerase
7.
Front Microbiol ; 3: 292, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22936927

RESUMO

In the aquatic environment, biofilms on solid surfaces are omnipresent. The outer body surface of marine organisms often represents a highly active interface between host and biofilm. Since biofilms on living surfaces have the capacity to affect the fluxes of information, energy, and matter across the host's body surface, they have an important ecological potential to modulate the abiotic and biotic interactions of the host. Here we review existing evidence how marine epibiotic biofilms affect their hosts' ecology by altering the properties of and processes across its outer surfaces. Biofilms have a huge potential to reduce its host's access to light, gases, and/or nutrients and modulate the host's interaction with further foulers, consumers, or pathogens. These effects of epibiotic biofilms may intensely interact with environmental conditions. The quality of a biofilm's impact on the host may vary from detrimental to beneficial according to the identity of the epibiotic partners, the type of interaction considered, and prevailing environmental conditions. The review concludes with some unresolved but important questions and future perspectives.

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