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1.
Mol Phylogenet Evol ; 148: 106808, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32243996

RESUMO

Although previous phylogenetic analyses suggested that the araphid diatom family Plagiogrammaceae is monophyletic, there is still not a clear understanding of relationships among the genera, and the taxonomy of several genera--Dimeregramma and Plagiogramma--remains questionable in light of paraphyly for both genera using molecular and morphological data. We have expanded the available DNA for molecular work for dozens of plagiogrammacean clones and analyzed 29 morphological characters from plagiogrammarian taxa and closely related genera, to increase understanding of the evolutionary history and systematics of the family and re-evaluate the current taxonomical classification of plagiogrammacean genera. The addition of more taxa and more data confirm the results from previous molecular phylogenies: most plagiogrammacean genera are monophyletic, except for Dimeregramma and Plagiogramma. Interestingly, the morphological analysis resolves only Talaroneis and Glyphodesmis as monophyletic. Given these results, we feel there is limited support for retaining Dimeregramma and Plagiogramma as distinct genera, and formally propose amending Plagiogramma and transferring six Dimeregramma species. As the Plagiogrammaceae is also one of the first-diverging clades of pennate diatoms, we also used these molecular data to estimate the age of the family, based on multiple calibration points derived from fossil taxa within or close to the Plagiogrammaceae. The results indicated that the Plagiogrammaceae evolved more than 114 million year ago and its diversification appears to correspond to a time of climate cooling. Additionally, we described a new monotypic genus (Coccinelloidea) with one new species C. gracilis, and five new species within established genera, e.g. Plagiogramma marginalis, Plagiogramma harenae, Plagiogramma porcipellis, Neofragilaria montgomeryii and Psammogramma anacarae.


Assuntos
Diatomáceas/classificação , Diatomáceas/genética , Filogenia , Animais , Teorema de Bayes , Mudança Climática , Diatomáceas/citologia , Diatomáceas/ultraestrutura , Fósseis , Análise de Sequência de DNA
2.
Protist ; 171(1): 125715, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32062589

RESUMO

Phaeodactylum tricornutum is an ecologically and evolutionarily relevant microalga that has developed into an important model for molecular biological studies on organisms with complex plastids. The diatom is particularly suitable for in vivo protein localization analyses via fluorescence microscopy in which the green fluorescent protein (GFP) and its derivatives are dominantly used. Whereas GFP fluorescence emission is usually measured between 500 and 520nm in confocal microscopy, the autofluorescence of the P. tricornutum plastid is detected above 625nm. Here we established the fluorescent protein mRuby3 as tag for efficient in vivo protein localization studies by expressing a codon-optimized gene in P. tricornutum. mRuby3 was directed to seven different subcellular localizations by means of full-length marker protein or N-/C-terminal targeting signal fusions; its emission was detected efficiently between 580 and 605nm, being unequivocally distinguishable from the plastid autofluorescence in vivo. Moreover, mRuby3 proved to be highly suitable for co-localization experiments using confocal laser scanning microscopy in which mRuby3 fusion proteins were expressed in parallel with GFP-tagged proteins. Our results show the potential of mRuby3 for its application in studying protein targeting and localization in P. tricornutum, particularly underlining its compatibility with GFP and the plastid autofluorescence in signal detection.


Assuntos
Diatomáceas/metabolismo , Proteínas Luminescentes/metabolismo , Diatomáceas/citologia , Proteínas de Fluorescência Verde/metabolismo , Proteínas Luminescentes/genética , Microscopia Confocal , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo
3.
Evolution ; 74(1): 188-200, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31461158

RESUMO

Fossil sequences provide observations of phenotypes within a lineage over time and represent essential data for increasing our understanding of phyletic evolution beyond microevolutionary timescales. I investigate if fossil time series of the diatom Stephanodiscus niagarae/yellowstonensis follow evolutionary dynamics compatible with hypotheses for how the adaptive landscape changes when a population enters a new environment. The lineage-which has a remarkably detailed stratigraphic record-invaded Yellowstone Lake immediately after recession of ice from the basin 14,000 years ago. Several phyletic models portraying different types of evolutionary dynamics-both compatible and not compatible with changes in the adaptive landscape following ecological opportunity-were fitted to the fossil times-series of S. niagarae/yellowstonensis. Different models best describe the three analyzed traits. Two of the models (a new model of decelerated evolution and an Ornstein-Uhlenbeck model) capture trait dynamics compatible with an event of ecological opportunity, whereas the third model (random walk) does not. Entering a new environment may accordingly affect trait dynamics for thousands of years, but the effects can vary across phenotypes. However, tests of model adequacy reveal shortcomings in all three models explaining the trait dynamics, suggesting model development is needed to more fully understand the phyletic evolution in S. niagarae/yellowstonensis.


Assuntos
Adaptação Biológica , Evolução Biológica , Diatomáceas/fisiologia , Fósseis , Diatomáceas/citologia , Lagos , Modelos Biológicos , Filogenia , Wyoming
4.
Nat Commun ; 10(1): 5610, 2019 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-31811139

RESUMO

Dynamic mapping of extracellular pH (pHe) at the single-cell level is critical for understanding the role of H+ in cellular and subcellular processes, with particular importance in cancer. While several pHe sensing techniques have been developed, accessing this information at the single-cell level requires improvement in sensitivity, spatial and temporal resolution. We report on a zwitterionic label-free pH nanoprobe that addresses these long-standing challenges. The probe has a sensitivity > 0.01 units, 2 ms response time, and 50 nm spatial resolution. The platform was integrated into a double-barrel nanoprobe combining pH sensing with feedback-controlled distance dependance via Scanning Ion Conductance Microscopy. This allows for the simultaneous 3D topographical imaging and pHe monitoring of living cancer cells. These classes of nanoprobes were used for real-time high spatiotemporal resolution pHe mapping at the subcellular level and revealed tumour heterogeneity of the peri-cellular environments of melanoma and breast cancer cells.


Assuntos
Imageamento Tridimensional/métodos , Neoplasias/diagnóstico por imagem , Neoplasias/patologia , Análise de Célula Única/métodos , Biofísica , Linhagem Celular Tumoral , Diatomáceas/citologia , Humanos , Concentração de Íons de Hidrogênio , Melanoma , Microscopia Eletrônica de Varredura
5.
PLoS One ; 14(12): e0226691, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31887164

RESUMO

The establishment of diatom communities depends on environmental factors such as the type of substrate and geographic conditions that influence the dispersal processes of these organisms. The main goal of this study was to evaluate the similarity between diatom communities associated with the macroalgae Prasiola crispa (Lightfoot) Kützing in relation to spatial distance from six sampled sites located in the South Shetland Islands, Maritime Antarctica. The diatom flora associated with Prasiola crispa was represented by 23 species distributed in 15 genera. Pinnularia australoschoenfelderi Zidarova, Kopalová & Van de Vijver, Luticola austroatlantica Van de Vijver, Kopalová, S.A.Spaulding & Esposito, Luticola amoena Van der Vijver, Kopalová, Zidarova & Levkov, Pinnularia austroshetlandica (Carlson) Cleve-Euler and Psammothidium papilio (D.E. Kellogg et al.) Kopalová & Zidarova were the most abundant species in our samples, together they represented 68% of the total number of individuals collected. There was great similarity and abundance of the diatom communites among the sampled points, which resulted in the absence of a linear relationship pattern with distance between sampling points. We conclude that distance was not a factor of differentiation of Antarctic diatom communities associated with terrestrial green macroalgae. This suggests that Antarctic environments may have unique characteristics with homogeneous abiotic factors, at least in relation to this substrate.


Assuntos
Diatomáceas/citologia , Alga Marinha/microbiologia , Regiões Antárticas , Demografia , Ecossistema , Ilhas , Densidade Demográfica
6.
Protist ; 170(4): 374-384, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31479910

RESUMO

In 1703 two articles appeared in the Transactions of the Royal Society, authored by an unnamed gentleman. The articles, with deference to Leeuwenhoeck, described recent observations made with a microscope. Clifford Dobell, in his biography of Leeuwenhoeck, remarked at length on the extraordinary quality of the illustrations and descriptions of "animalcules". He declared the anonymous author to be the scion and master draughtsman of Leeuwenhoeck's followers. Still today, one of the illustrations is credited with being the first unambiguous depiction of a diatom. Here I present evidence that the anonymous author was Charles King of Staffordshire and evidence of his talent. John Hill is often credited for the first naming and illustrating Paramecium and other ciliates in his 1752 book, but it has been claimed repeatedly that he copied the anonymous 1703 illustrations without attribution. Here, the illustrations from 1703 and 1752 are given, and casual examination suffices to show not only that the illustrations were copied, but also that the 1703 illustrations (and text descriptions) of Charles King are of a far higher quality than those of John Hill. Although very little is known about Charles King, he deserves recognition as a pioneer of protistology.


Assuntos
Livros Ilustrados/história , Diatomáceas/citologia , História do Século XVIII , Microbiologia/história , Microscopia
7.
Biomolecules ; 9(8)2019 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-31366180

RESUMO

: Of all the eukaryotic algal groups, diatoms make the most substantial contributions to photosynthesis in the contemporary ocean. Understanding the biological innovations that have occurred in the diatom chloroplast may provide us with explanations to the ecological success of this lineage and clues as to how best to exploit the biology of these organisms for biotechnology. In this paper, we use multi-species transcriptome datasets to compare chloroplast metabolism pathways in diatoms to other algal lineages. We identify possible diatom-specific innovations in chloroplast metabolism, including the completion of tocopherol synthesis via a chloroplast-targeted tocopherol cyclase, a complete chloroplast ornithine cycle, and chloroplast-targeted proteins involved in iron acquisition and CO2 concentration not shared between diatoms and their closest relatives in the stramenopiles. We additionally present a detailed investigation of the chloroplast metabolism of the oil-producing diatom Fistulifera solaris, which is of industrial interest for biofuel production. These include modified amino acid and pyruvate hub metabolism that might enhance acetyl-coA production for chloroplast lipid biosynthesis and the presence of a chloroplast-localised squalene synthesis pathway unknown in other diatoms. Our data provides valuable insights into the biological adaptations underpinning an ecologically critical lineage, and how chloroplast metabolism can change even at a species level in extant algae.


Assuntos
Cloroplastos/metabolismo , Diatomáceas/citologia , Diatomáceas/metabolismo , Biodiversidade , Diatomáceas/classificação , Diatomáceas/genética , Genômica
8.
Proc Natl Acad Sci U S A ; 116(32): 15997-16002, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31346087

RESUMO

Finding a partner in an inherently unsteady 3-dimensional system, such as the planktonic marine environment, is a difficult task for nonswimming organisms with poor control over their orientation. We experimentally investigate the process of cell pairing in pennate marine diatoms and present field evidence of its occurrence in the ocean. We describe the mechanism as a 3-step process in which pennate diatoms (i) vertically reorient while sinking from surface turbulent waters to a more stable environment (i.e., under the seasonal pycnocline), (ii) segregate from incompatible partners (e.g., dead or different sized cells), and (iii) pair with other partners as a result of the hydrodynamic instabilities generated by collective cell sinking. This is, eminently, a cell abundance-dependent process, therefore being more effective when population sinking is synchronized. We suggest that this selective process, enabling matching of size-compatible healthy partners, could be fundamental in understanding sexual reproduction in pennate diatoms.


Assuntos
Diatomáceas/citologia , Movimento , Plâncton/citologia , Microfluídica , Reologia
9.
Aquat Toxicol ; 212: 20-27, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31039523

RESUMO

Polybrominated diphenyl ethers (PBDEs), a series of highly persistent organic pollutants (POPs), are ubiquitous in marine ecosystems. As key primary producers, microalgae are of great importance on evaluating the environmental outcome of PBDEs pollution. In this study, the toxic mechanisms of BDE-47 on the marine diatom Thalassiosira pseudonana were evaluated by measuring multiple physiological processes. Three concentrations of BDE-47 (25, 15 and 5 µg L-1) were used along with two controls (blank: no BDE-47 or DMSO; negative control: only DMSO). Experiments lasted 144 h (6 days), in which the actual BDE-47 concentrations, cell densities, nutrient (nitrate and phosphate) uptake, pigment compositions, photosynthetic physiology, cell morphology and cellular contents (organic carbon and nitrogen) were measured at 12-48 h intervals. The toxic mechanisms of BDE-47 on T. pseudonana cells were evaluated by measuring multiple physiological processes including photosynthesis, nutrient uptake, cellular material synthesis and cell cycle progressions. The cell divisions of T. pseudonana were severely inhibited by the stress of BDE-47, but the photosynthetic parameters were much less declined and recovered earlier than the cell divisions in the same BDE-47 treatments. The unsuppressed uptake rates of nutrients, increased cell volume and cellular contents indicated the cellular material synthesis proceeded normally. Finally, we found that the cell cycle was arrested in G2/M phase under the stress of BDE-47, we thus concluded that the inhibition of cell divisions by BDE-47 was not due to the lack of energy or cellular materials, where the cell cycle arrest happened; this might be the most important toxicological outcome.


Assuntos
Diatomáceas/efeitos dos fármacos , Diatomáceas/fisiologia , Éteres Difenil Halogenados/toxicidade , Fenômenos Fisiológicos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Carbono/metabolismo , Ciclo Celular/efeitos dos fármacos , Diatomáceas/citologia , Diatomáceas/crescimento & desenvolvimento , Nitrogênio/metabolismo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Pigmentos Biológicos/metabolismo , Estresse Fisiológico/efeitos dos fármacos
10.
Appl Opt ; 58(12): 3104-3114, 2019 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-31044784

RESUMO

Modern microscopes are designed with functionalities that are tailored to enhance image contrast. Dark-field imaging, phase contrast, differential interference contrast, and other optical techniques enable biological cells and other phase-only objects to be visualized. Quantitative phase imaging refers to an emerging set of techniques that allow for the complex transmission function of the sample to be measured. With this quantitative phase image available, any optical technique can then be simulated; it is trivial to generate a phase contrast image or a differential interference contrast image. Rheinberg illumination, proposed almost a century ago, is an optical technique that applies color contrast to images of phase-only objects by introducing a type of optical staining via an amplitude filter placed in the illumination path that consists of two or more colors. In this paper, the complete theory of Rheinberg illumination is derived, from which an algorithm is proposed that can digitally simulate the technique. Results are shown for a number of quantitative phase images of diatom cells obtained via digital holographic microscopy. The results clearly demonstrate the potential of the technique for label-free color staining of subcellular features.


Assuntos
Diatomáceas/citologia , Holografia/métodos , Iluminação , Microscopia de Contraste de Fase/métodos , Coloração e Rotulagem/métodos , Algoritmos
11.
Sci Rep ; 9(1): 7342, 2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31089153

RESUMO

The secreted mucilage trails of the diatom Navicula sp. in the process of motility were studied by scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and Raman spectra etc. Contrary to previous studies, force measurement was taken directly on the mucilage trails of live cells using the method of in situ force mapping by AFM. The retraction force curve presented an increased tip-substrate peak and a small saw-tooth pattern tip-mucilage peak. Especially, same measurements on various substrates with different surface energy revealed that the mucilage trails actually functioned as a medium increasing the adhesive force between the diatom and substrates, which is crucial to diatom's adhesion and locomotion. In addition, the mechanical properties of mucilage trails were quite different from mucilage strands in the maximum adhesive force and the maximum polymer extension length. Raman spectra indicated the difference in compositions that both of the two kinds of mucilages had proteins and polysaccharide, but the mucilage strands contained some other components with C=O, -CH2- and -CH3 asymmetric and symmetric stretches. This research hammers out more precise information about mucilage trails which would be useful in terms of diatom motility and biofouling prevention.


Assuntos
Diatomáceas/metabolismo , Polissacarídeos/metabolismo , Adesivos/metabolismo , Incrustação Biológica , Adesão Celular , Movimento Celular , Diatomáceas/citologia , Proteínas/metabolismo
12.
J Biol Phys ; 45(2): 213-234, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31140117

RESUMO

Diatoms are microalgae encased in highly structured and regular frustules of porous silica. A long-standing biological question has been the function of these frustules, with hypotheses ranging from them acting as photonic light absorbers to being particle filters. While it has been observed that the girdle band pores of the frustule of Coscinodiscus sp. resemble those of a hydrodynamic drift ratchet, we show using scaling arguments and numerical simulations that they cannot act as effective drift ratchets. Instead, we present evidence that frustules are semi-active filters. We propose that frustule pores simultaneously repel viruses while promoting uptake of ionic nutrients via a recirculating, electroosmotic dead-end pore flow, a new mechanism of "hydrodynamic immunity".


Assuntos
Diatomáceas/imunologia , Diatomáceas/virologia , Hidrodinâmica , Diatomáceas/citologia , Diatomáceas/metabolismo , Modelos Biológicos , Porosidade , Dióxido de Silício/química , Dióxido de Silício/metabolismo
13.
Biomater Sci ; 7(5): 1833-1841, 2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-30907899

RESUMO

Uncontrollable hemorrhage is the main cause of death in military and civilian accidents. It is therefore necessary and an urgent requirement to develop a safe and efficient hemostatic material. In this study, the hemostatic performance of frustules of three centric diatom species (Thalassiosira weissflogii, Thalassiosira sp., and Cyclotella cryptica) with similar shapes and different sizes was investigated. The complicated structure of T. weissflogii, leading to its highest BET surface area (169.5 m2 g-1) and liquid absorption (51.4 ± 1.6 times the weight of liquid), exhibited the shortest hemostasis time (158 ± 8.19 s) in in vitro blood coagulation. Thalassiosira sp. had a shorter hemostasis time (167.33 ± 14.74 s) than that of QuikClot® and C. cryptica, indicating that diatom size also played an important role in hemostasis due to the interface reaction between the material and plasma protein. The in vivo hemostasis results further confirmed this conclusion. Diatom frustules also exhibited favorable blood compatibility (<5%), and no significant cell toxicity could be observed from the three frustules. Our results suggest that the coagulation effect of frustules is strengthened upon a decrease in the size and increase in the liquid absorbability. This report provides valuable information for the medical application of diatom frustules in the field of hemorrhage control.


Assuntos
Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Fenômenos Químicos , Diatomáceas/citologia , Hemorragia/tratamento farmacológico , Animais , Materiais Biocompatíveis/uso terapêutico , Materiais Biocompatíveis/toxicidade , Coagulação Sanguínea/efeitos dos fármacos , Parede Celular/química , Hemólise/efeitos dos fármacos , Hemorragia/fisiopatologia , Teste de Materiais , Camundongos , Porosidade , Coelhos , Ratos
14.
Sci Total Environ ; 656: 1063-1070, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30625638

RESUMO

Microcystis aeruginosa (M. aeruginosa) commonly blooms in summer while Cyclotella meneghiniana (C. meneghiniana) outbreaks in fall in water reservoirs of Southeast China. Pre-oxidation has been demonstrated to enhance the algae removal from chemical coagulation processes. However, excessive dosage of pre-oxidant can increase the disinfection by-products formation potential (DBPsFP). Additionally, the DBPs formation mechanisms from algae during the pre-oxidation-coagulation-chlorination processes have not well elucidated. In this study, the objectives were to investigate the trichloromethane (TCM) formation, the changes of water quality indexes, and the morphology changes of algal cells from M. aeruginosa or C. meneghiniana contaminated water during potassium permanganate (KMnO4) or chlorine (Cl2) pre-oxidation-coagulation-chlorination disinfection. The results showed that the TCM yield for two algal species decreased with the dosage increase of KMnO4 pre-oxidation, but increased with the dosage increase of pre-chlorination. Therefore, the 2.0 mg/L KMnO4 or 0.5 mg/L Cl2 was proposed as the optimal dosage for preventing both M. aeruginosa blooms in summer and for C. meneghiniana outbreaks in fall. M. aeruginosa exhibited a slightly higher TCM yield than C. meneghiniana in these treatment processes. Based on the release of potassium (K) ion and SEM analysis, KMnO4 had less damage on cell integrity than Cl2 at the dosage ≤2.0 mg/L. In addition, C. meneghiniana was easier to be disrupted by both pre-oxidants than M. aeruginosa, combining with subsequent coagulation led to different value of dissolved organic carbon (DOC), UV-visible absorbance (UV254) and turbidity.


Assuntos
Cloro/química , Clorofórmio/metabolismo , Diatomáceas/metabolismo , Microcystis/metabolismo , Permanganato de Potássio/química , Purificação da Água/métodos , Diatomáceas/citologia , Diatomáceas/efeitos dos fármacos , Relação Dose-Resposta a Droga , Floculação , Halogenação , Microcystis/citologia , Microcystis/efeitos dos fármacos , Oxidantes/química , Oxirredução , Qualidade da Água
15.
Fa Yi Xue Za Zhi ; 35(6): 706-709, 2019 Dec.
Artigo em Inglês, Chinês | MEDLINE | ID: mdl-31970958

RESUMO

Abstract: Objective To discuss the application value of diatom examination in lung tissue for the forensic diagnosis of drowning. Methods The experimental animals were divided randomly into drowning, postmortem submergence and dying on land group. Diatoms in lung tissue and drowning fluid were analyzed quantitatively by microwave digestion-vacuum filtration-automated scanning electron microscopy diatom examination method. The ratios of content of diatoms in lung tissue and drowning fluid (CL/CD ratio) were recorded. Results The CL/CD ratios of experimental rabbits in the drowning group (5.82±3.50) were much higher than that of postmortem submergence group (0.47±0.35); the CL/CD ratios of different parts of the lung lobes of experimental pigs in the drowning group were higher than that of postmortem submergence group (P<0.05); in seawater, brackish water, river fresh water and lake fresh water, the CL/CD ratios of experimental pigs in the drowning group were higher than that of postmortem submergence group (P<0.05). In animal experiments, all the cases with CL/CD ratio >1.6 were from drowning group. Conclusion CL/CD ratio is an indicator with good application prospects in the diagnosis of drowning.


Assuntos
Diatomáceas , Afogamento , Animais , Autopsia , Diatomáceas/citologia , Afogamento/diagnóstico , Pulmão , Microscopia Eletrônica de Varredura , Coelhos , Distribuição Aleatória , Suínos
16.
Environ Monit Assess ; 191(1): 29, 2018 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-30591969

RESUMO

In this paper, the algal cell density of cyanobacteria, green algae, and diatoms and their responses to the hydrochemical factors were analyzed to reveal the structural characteristics of water quality in an urban river. A total of nine sampling sites from upstream to downstream was explored in our study. At each site, the density of algae was identified every week during the wet season (June-October) from 2012 to 2017, and in situ detection was used for the relative 11 hydrochemical variables. The temporal and spatial characteristics of 14 variables were analyzed using a heatmap coupled with the cluster analysis method. The trend of each parameter was analyzed using the smoothing method with locally weighted regression. The nonmetric multidimensional scaling method was employed to detect the temporal and spatial similarities among algae along hydrochemical gradients. The responses of algal density to hydrochemical variables were analyzed using a redundancy analysis. The results showed that the water temperature (Wtemp), pH, dissolved oxygen (DO), cyanobacteria, and diatoms exhibited significant declining trends, and significant increasing trends were shown in the permanganate index, chemical oxygen demand, total nitrogen, ammonia nitrogen, and total phosphorus; the cyanobacteria exhibited certain differences with green algae and diatoms in summer and the downstream areas of the river. The temporal-spatial homogeneity of algal to hydrochemical variables showed the key influencing factors of Wtemp for cyanobacteria density, chlorophyll for green algae density, DO, and pH for diatoms. The results presented here are valuable for deepening our understanding of river ecosystem evaluations and effective environmental management, as well as an important reference for the sustainable development of aquatic biological resources.


Assuntos
Clorófitas/citologia , Cianobactérias/citologia , Diatomáceas/citologia , Monitoramento Ambiental/métodos , Rios/química , Movimentos da Água , China , Clorofila/análise , Clorófitas/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Ecossistema , Eutrofização , Nitrogênio/análise , Fósforo/análise , Estações do Ano , Urbanização , Qualidade da Água
18.
J Phycol ; 54(6): 918-922, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30270437

RESUMO

Pseudo-nitzschia nanaoensis sp. nov. is described from waters around Nan'ao Island (South China Sea), using morphological data and molecular evidence. This species is morphologically most similar to P. brasiliana, but differs by a denser arrangement of fibulae, interstriae, and poroids, as well as by the structure of the valvocopula and the narrow second band. Pseudo-nitzschia nanaoensis constitutes a monophyletic lineage and is well differentiated from other species on the LSU and ITS2 sequence-structure trees. Pseudo-nitzschia nanaoensis makes up the basal node on the LSU tree, and forms a sister clade with a group of P. pungens and P. multiseries on the ITS2 tree. The ability of cultured strains to produce domoic acid was assessed, including its possible induction by the presence of a copepod and brine shrimp, by liquid chromatography-tandem mass spectrometry. However, no strains showed detectable domoic acid.


Assuntos
Diatomáceas/classificação , Ácido Caínico/análogos & derivados , Toxinas Marinhas/metabolismo , China , DNA de Protozoário/análise , DNA Espaçador Ribossômico/análise , Diatomáceas/citologia , Diatomáceas/genética , Diatomáceas/ultraestrutura , Ácido Caínico/metabolismo , Filogenia
19.
Mar Pollut Bull ; 135: 562-568, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30301074

RESUMO

The characteristics of phytoplankton assemblages were analyzed by the Utermöhl method in the southern Yellow Sea in summer, 2008. A total of 113 species (including varieties and forms), belonging to 51 genera and 3 phyla, were identified. Diatom was the most dominant group. The dominant species included Eucampia zoodiacus, Leptocylindrus danicus, Chaetoceros affinis, Thalassionema nitzschioides, Skeletonema costatum, Paralia sulcata and Chaetoceros tortissimus, which were eurytopic and temperate species. The cell abundance of phytoplankton ranged from 0.04 to 620.08 cells·mL-1 with an average of 27.52 cells·mL-1. Horizontally, the cell abundance showed a decreasing trend from the south to the north. In terms of vertical distribution, the values in surface and subsurface water layers were higher than those in bottom water layers. Results of correlation analysis showed that phytoplankton cell abundance was positively correlated with water temperature, ammonia and nitrite concentrations, and negatively correlated with salinity and silicate concentration.


Assuntos
Diatomáceas/fisiologia , Fitoplâncton , Biodiversidade , China , Diatomáceas/citologia , Monitoramento Ambiental/métodos , Oceanos e Mares , Fitoplâncton/citologia , Salinidade , Estações do Ano , Temperatura
20.
Protist ; 169(4): 466-483, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30025232

RESUMO

Reproductive development in Ardissonea crystallina revealed a unique mode of enlargement involving a combination of novel and known structures. In light microscopy, auxospores of this elongated polar centric diatom were superficially similar to the auxospores of pennates. With SEM we found three different components in the auxospore wall. In the youngest, nearly spherical cell-stage, the wall consisted only of a delicate veil containing minute siliceous spherules. Incunabular elements developed underneath this layer. Second, a previously unknown form of specifically modified incunabular scales shaped the subsequent ellipsoidal-capsule auxospore stage. Third, there was a clear contribution of scales to the development of scaly transverse perizonial bands (or scaly bands, for brevity). Such bands, although noted by previous researchers, have not been fully appreciated for the evolutionary information they may convey: possibly common among polar centrics but not pennates. Finally, we propose maintaining the term transverse perizonium to refer to these bands in polar diatoms, but to introduce the differentiation of scaly bands described here from pinnate bands (currently known as typical of pennates). Further research into band types among polar centrics may provide new insights into the relationship between the groups within polar centrics that are currently unresolved by molecular methods.


Assuntos
Diatomáceas/citologia , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Esporos/citologia
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