Unicellular Forms Research Articles

The Heavy Links between Geological Events and Vascular Plants Evolution: A Brief Outline.

Since the rise of photosynthesis, life has influenced terrestrial atmosphere, particularly the O2 and the CO2 content (the latter being originally more than 95%), changing the chemistry of waters, atmosphere, and soils. Billions of years after, a far offspring of these first unicellular forms conquered emerging lands, not only completely changing landscape, but also modifying geological cycles of deposition and erosion, many chemical and physical characteristics of soils and fresh waters, and, more, the cycle of various elements. So, there are no doubts that vascular plants modified geology; but it is true that also geology has affected (and, more, has driven) plant evolution. New software, PyRate, has determined vascular plant origin and diversification through a Bayesian analysis of fossil record from Silurian to today, particularly observing their origination and extinction rate. A comparison between PyRate data and geological history suggests that geological events massively influenced plant evolution and that also the rise of nonflowering seed plants and the fast diffusion of flowering plants can be explained, almost partly, with the environmental condition changes induced by geological phenomena.

Abundance and diversity of unicellular, filamentous cyanobacteria (BGA) and other higher algal genera in different rice fields of North 24 Parganas District in West Bengal, India

The distribution of unicellular and filamentous Blue green algae in relation to seasonal variation in rice fields in three major rice growing different blocks of North 24 parganas in west Bengal has been under taken. Present research paper deals with continued three successive years (2011-2014) studied for the first time. The different physicochemical parameters were chosen for this study. The occurrence of Cyanobacteria and altogether 48 species of Nitrogen fixing Cyanobacteria samples belonging to 25 genera and various orders were isolated in different rice growing fields. The increasing range of soil pH was certainly the important factor for the development of BGA up to certain limits. Comparatively more number of filamentous and heterocystous forms were developed in July to October (kharif season) and less number of unicellular forms were in November to June (Rabi season). When water level was low, Starting the crop season the rice growing fields developed mainly Unicellular, colonial and Non-Heterocystous filamentous Cyanobacteria and slight developed water level in the middle of rice growing time, Non-Heterocystous and Heterocystous Cyanobacteria were observed. When water level was more and at the end of rice crop season mostly Heterocystous and filamentous Cyanobacteria (BGA) were developed.

The cell survival pathways of the primordial RNA-DNA complex remain conserved in the extant genomes and may function as proto-oncogenes.

Malignantly transformed (cancer) cells of multicellular hosts, including human cells, operate activated biochemical pathways that recognizably derived from unicellular ancestors. The descendant heat shock proteins of thermophile archaea now chaperon oncoproteins. The ABC cassettes of toxin-producer zooxantella Symbiodinia algae pump out the cytoplasmic toxin molecules; malignantly transformed cells utilize the derivatives of these cassettes to get rid of chemotherapeuticals. High mobility group helix-loop-helix proteins, protein arginine methyltransferases, proliferating cell nuclear antigens, and Ki-67 nuclear proteins, that protect and repair DNA in unicellular life forms, support oncogenes in transformed cells. The cell survival pathways of Wnt-β-catenin, Hedgehog, PI3K, MAPK-ERK, STAT, Ets, JAK, Pak, Myb, achaete scute, circadian rhythms, Bruton kinase and others, which are physiological in uni- and early multicellular eukaryotic life forms, are constitutively encoded in complex oncogenic pathways in selected single cells of advanced multicellular eukaryotic hosts. Oncogenes and oncoproteins in advanced multicellular hosts recreate selected independently living and immortalized unicellular life forms, which are similar to extinct and extant protists. These unicellular life forms are recognized at the clinics as autologous "cancer cells".

Distribution pattern of freshwater cyanobacteria in Kaiga region of Western Ghats of Karnataka

This study deals with the identification of 59 cyanobacterial species belonging to 27 genera from different freshwater habitats of Kaiga in Uttara Kannada district of Karnataka during the period from June 2009 to May 2011. Samplings were made during pre-monsoon; monsoon and post-monsoon sampling have been carried out for the duration of 2 years. The study deals with the occurrence of cyanobacterial species in five different aquatic habitats in Kaiga region, with respect to a change in the physico-chemical properties of water. The cyanobacterial diversity is maximum in monsoon season compared to post-monsoon; it was least during pre-monsoon. Among cyanobacteria non-heterocystous filamentous forms were dominant followed by unicellular forms, whereas heterocystous forms were least in number. It was also found that the physicho-chemical properties of water have the influence on the richness of cyanobacterial community. This study indicates the maximum occurrence and abundance of Chroococaceae (23.73%) and Phormidaceae (18.64%) members in all the sites, whereas Stigonemataceae (1.7%) shows very less occurrence. Among the cyanobacteria identified non-heterocystous filamentous forms were dominant followed by unicellular forms; whereas heterocystous forms were least in number.

Temperature dependence of biological processes: Implications for food quality, safety and security

Nutrition is well outside my area of expertise although my first degree was in Agriculture in which Animal Physiology and nutrition was an important part of the course. More recently at UTas we have had several research projects the aim of which was to discover microbial sources of polyunsaturated fatty acids. Thraustochytrids were the most promising organisms and an interesting outcome was that these grew in media with no added salt without affecting PUFA production. Several studies have optimised PUFA production by varying media composition, salinity and temperature. Optimum growth rates were at 25e30 oC and continued to a minimum of 5e10 oC, similar to many other marine organisms including bacteria. That is they fit into the thermal category of psychrotropic organisms which merge with mesophiles as temperatures increase. Temperature plays a major role in the rate at which biological populations develop and potentiates the effect of other factors such as oxygen availability, salinity, hydrostatic pressure and pH. In microbiology time scales range from milliseconds for enzyme catalysed reactions to doubling times of ~7 minutes for Clostridium perfringens, to days, weeks or months for psychrophilic bacteria growing optimally, to > 3.5 billion years to reach the current level of evolutionary adaptation. The temperature dependence of biological process rates requires knowledge of microbial ecology (rate of population increase) and physiology (biochemical reaction rates and physiological control in individual cells). The integration of these disciplines into ecophysiological studies supported by omics technologies is necessary to underpin advances in understanding how to inhibit or stimulate microbial growth. At UTas we have studied the ecophysiology of food borne bacteria including pathogens and spoilage organisms for 40 years. The original aim was to produce mathematical models to predict the rate of growth or decline of populations in foods, and this continues but in the last decade we have expanded into other ecosystems. The field of Predictive Microbiology has changed the paradigm of foodmicrobiology from one of testing and retrospective reporting of results to prospective reporting based on the temperature history of a process interpreted by a predictive model. A major outcome of this work was mandating the use of the Refrigeration Index by The Australian Quarantine Inspection Service in the revised Export Control Meat and Meat Products) Order, AQIS 2005(http://www.daffa.gov.au/aqis/export/meat/elmer-3). The models developed and validated to that time were empirical and the current state of the art can be found in Corkrey et.al 2014, the abstract of which is reproduced below: “Life on Earth is capable of growing from temperatureswell below freezing to above the boiling point of water, with some organisms preferring cooler and others hotter conditions. The growth rate of each organism ultimately depends on its intracellular chemical reactions. Here we show that a thermodynamic model based on a single, rate-limiting, enzyme-catalysed reaction accurately describes population growth rates in 230 diverse strains of unicellular and multicellular organisms. Collectively these represent all three domains of life, ranging from psychrophilic to hyperthermophilic, and including the highest temperature so far observed for growth (122 C). The results provide credible estimates of thermodynamic properties of proteins and obtain, purely from organism intrinsic growth rate data, relationships betweenparameterspreviously identifiedexperimentally, thusbridgingagap between biochemistry and whole organism biology. We find that growth rates of both unicellular and multicellular life forms can be described by the same temperature dependence model. The model results provide strong support for a single highly-conserved reaction present in the last universal common ancestor (LUCA). This is remarkable in that itmeans that the growth rate dependence on temperature of unicellular and multicellular life forms that evolved over geological time spans can be explainedby the samemodel”. Progress in integrating applications in food quality, safety and security will be reported in November.

Extensive hydrogen supersaturations in the western South Atlantic Ocean suggest substantial underestimation of nitrogen fixation

AbstractThe nitrogen cycle is fundamental to Earth's biogeochemistry. Yet major uncertainties of quantification remain, particularly regarding the global oceanic nitrogen fixation rate. Hydrogen is produced during nitrogen fixation and will become supersaturated in surface waters if there is net release from diazotrophs. Ocean surveys of hydrogen supersaturation thus have the potential to illustrate the spatial and temporal distribution of nitrogen fixation and to guide the far more onerous but quantitative methods for measuring it. Here we present the first transect of high resolution measurements of hydrogen supersaturations in surface waters along a meridional 10,000 km cruise track through the Atlantic. We compare measured saturations with published measurements of nitrogen fixation rates and also with model‐derived values. If the primary source of excess hydrogen is nitrogen fixation and has a hydrogen release ratio similar to Trichodesmium, our hydrogen measurements would point to similar rates of fixation in the North and South Atlantic, roughly consistent with modeled fixation rates but not with measured rates, which are lower in the south. Possible explanations would include any substantial nitrogen fixation by newly discovered diazotrophs, particularly any having a hydrogen release ratio similar to or exceeding that of Trichodesmium; undersampling of nitrogen fixation south of the equator related to excessive focus on Trichodesmium; and methodological shortcomings of nitrogen fixation techniques that cause a bias toward colonial diazotrophs relative to unicellular forms. Alternatively, our data are affected by an unknown hydrogen source that is greater in the southern half of the cruise track than the northern.

Identification of an elongation factor 1Bγ protein with glutathione transferase activity in both yeast and mycelial morphologies from human pathogenic Blastoschizomyces capitatus

Blastoschizomyces capitatus is an uncommon, opportunistic pathogenic fungus, which causes invasive and disseminated infections. This microorganism is normally present in both environmental and normal human flora. Within a host, B. capitatus is able to grow in both unicellular yeast and multicellular filamentous growth forms. In this study, we obtained in vitro morphological conversion of B. capitatus from yeast-to-mycelial phase to investigate the presence and expression of glutathione transferase (GST) enzymes in both cell forms. A protein with GST activity using the model substrate 1-chloro-2,4-dinitrobenzene was detected in both morphologies and identified by tandem mass spectrometry as a eukaryotic elongation factor 1Bγ (eEF1Bγ) protein, a member of the GST superfamily. No significant difference in GST-specific activity and kinetic constants were observed between mycelial and yeast forms, indicating that eEF1Bγ protein did not show differential expression between the two phases.

Antitumor activity of hierridin B, a cyanobacterial secondary metabolite found in both filamentous and unicellular marine strains.

Cyanobacteria are widely recognized as a valuable source of bioactive metabolites. The majority of such compounds have been isolated from so-called complex cyanobacteria, such as filamentous or colonial forms, which usually display a larger number of biosynthetic gene clusters in their genomes, when compared to free-living unicellular forms. Nevertheless, picocyanobacteria are also known to have potential to produce bioactive natural products. Here, we report the isolation of hierridin B from the marine picocyanobacterium Cyanobium sp. LEGE 06113. This compound had previously been isolated from the filamentous epiphytic cyanobacterium Phormidium ectocarpi SAG 60.90, and had been shown to possess antiplasmodial activity. A phylogenetic analysis of the 16S rRNA gene from both strains confirmed that these cyanobacteria derive from different evolutionary lineages. We further investigated the biological activity of hierridin B, and tested its cytotoxicity towards a panel of human cancer cell lines; it showed selective cytotoxicity towards HT-29 colon adenocarcinoma cells.

Bioprospecting and indexing the microalgal diversity of different ecological habitats of India

Our study reports the collection, biodiversity analyses, isolation and identification of microalgae from different habitats of India. Cyanophyceae and Chlorophyceae were the most dominant algal groups recorded, with the highest number being recorded for non-heterocystous cyanobacteria (48), followed by 44 unicellular forms. Sagar Island, Sunderbans recorded the greatest number of algae, and unicellular/colonial green algae were present in all the samples. Shannon's Diversity Index was highest in Koikhali, Sunderbans, followed by Rushikulya River, Odisha. Selective enrichment, purification through serial dilution followed by plating and regular observations led to the isolation of sixteen strains. Identification was done by using microscopic observations, supported with standard monographs and classified as belonging to seven genera (Chlorella, Chlorococcum, Kirchneria, Scenedesmus, Chlamydomonas, Tetracystis and Ulothrix). 18S rDNA sequencing was undertaken for four strains. The set of sixteen strains were screened under standard cultural conditions for their growth kinetics and Chlorella sorokiniana MIC-G5, followed by Chlorella sp. MIC-G4 exhibited the highest growth rates. The strain Chlorococcum sp. MIC-G2 recorded highest chlorophyll, while MIC-G3 ranked highest for carbohydrates. The study aided in identifying the dominant microalgae in the diverse habitats and characterizing their growth rate and carbohydrate content, providing a valuable germplasm for further utilization in agriculture and industry.

The tangled taxonomic history of Dictyococcus, Bracteacoccus and Pseudomuriella (Chlorophyceae, Chlorophyta) and their distinction based on a phylogenetic perspective

Fučíková K., Rada J.C. and Lewis L.A. 2011. The tangled taxonomic history of Dictyococcus, Bracteacoccus, and Pseudomuriella (Chlorophyceae, Chlorophyta) and their distinction based on a phylogenetic perspective. Phycologia 50: 422–429. DOI: 10.2216/10-69.1Phylogenetically diverse algae, especially unicellular forms from similar habitats, can have nearly indistinguishable morphology when viewed with light microscopy. Consequently, historical taxonomy of many green coccoids based on light microscopy is not only inaccurate but also highly tangled because over time taxonomists have emphasized different traits. In the case of the three morphologically similar genera, Bracteacoccus, Dictyococcus and Pseudomuriella, we present an example of molecular data helping to resolve phylogenetic relationships of coccoids and facilitating the interpretation of morphology. The three genera are shown to be distinct lineages by our phylogenetic analysis of 18S and rbcL sequence data. Our photomicroscopic observations suggest that Bracteacoccus and Pseudomuriella are morphologically cryptic genera, whereas Dictyococcus can be clearly distinguished by its chloroplast morphology. Additionally, we show that Bracteacoccus engadinensis and Dictyococcus schumacherensis are more closely related to Pseudomuriella aurantiaca than to other examined Bracteacoccus and Dictyococcus representatives, respectively. We therefore propose the transfer of these species to the genus Pseudomuriella.

Role of Cell Hydrophobicity on Colony Formation in Microcystis (Cyanobacteria)

AbstractColony formation is highly import ant for the competitive advantage of the cyanobacterium Microcystis over other phytoplankton species. The laboratory‐grown colonial Microcystis strains isolated from Lake Taihu (China) maintained colonial forms under the low light condition (10 μE m–2 s–1). The cell surface hydrophobicities of the Microcystis colonies were measured by cyanobacterial adherence to xylene in comparison with unicellular Microcystis strains. The cells of the tested colonial strains were all hydrophobic, while the cells of the tested unicellular strains were all hydrophilic. Incubation under the higher light condition (75 μE m–2 s–1) leaded to the significant decrease in the cell hydrophobicities of the colonial Microcystis and the transition from colonial forms to unicellular forms. These findings indicated that the cell hydrophobicity of Microcystis may play a role in cell‐cell adherence and colony formation. Phosphate‐limitation, nitrate‐limitation and pH did not affect cell hydrophobicities of colonial Microcystis. Treatment with proteolytic enzymes had no effect on the cell hydrophobicity, indicating that cell surface proteins did not contribute to high cell hydrophobicity. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Phytoplankton assemblages in a reservoir cascade of a large tropical - subtropical river (SE, Brazil)

The phytoplankton assemblages from eight reservoirs of the Paranapanema River were studied during two consecutive years. Chlorophyceae and Bacillaryophyceae dominated in richness. The observed high number of taxa, 234, reflects the extensive sampling programme and evidences the necessity of considering the whole hydrograph basin to assess the biodiversity status of inland water ecosystems. The dams had a negative effect on phytoplankton richness, with higher number of taxa associate to riverine (non-regulated) stretches. The tributary rivers also exhibited high species richness, showing the importance of considering the lateral dimension, in addition to the longitudinal one, for aquatic biota inventories in large river basins/reservoirs. Richness and diversity were also positively influenced by the connectivity with lateral wetlands (macrophyte-dominated lakes) due to the periphyton influence. The phytoplankton abundance/biomass was not influenced by higher water retention time. Higher values occurred in the middle basin stretches (river-passage reservoirs) due to the increase in the trophic conditions. There was a positive correlation with phosphorus. Poorer light conditions in the cascade do not limit the phytoplankton biomass, with assemblages dominated by species tolerant to turbulent conditions and high mineral turbidity. Bacillariophyceae and Cryptophyceae dominated numerically. The first group (unicellular forms) was prominent in the large and oligotrophic upstream reservoirs. The second was highly abundant in the river-passage (low retention time), and more eutrophic, reservoirs. Cyanophyceae growth is probably controlled by advection processes (wash-out effect). The zooplankton does not control the phytoplankton biomass and the diversity of both groups is positively associated in the cascade. The structure of the phytoplankton assemblages showed to be a good indicator of the operationally distinct reservoirs of the Paranapanema cascade and also reflected the changes in the trophic conditions along the basin.

Cellular “ bauplans”: Evolving unicellular forms by means of Julia sets and Pickover biomorphs

The universe of cellular forms has received scarce attention by mainstream neo-Darwinian views. The possibility that a fundamental trait of biological order may consist upon, or be guided by, developmental processes not completely amenable to natural selection was more akin to previous epochs of biological thought, i.e. the “ bauplan” discussion. Thirty years ago, however, Lynn and Tucker studied the biological mechanisms responsible for defining organelles position inside cells. The fact that differentiated structures performing a specific function within the eukaryotic cell (i.e. mitochondrion, vacuole, or chloroplast) were occupying specific positions in the protoplasm was the observational and experimental support of the ‘morphogenetic field’ notion at the cellular level. In the present paper we study the morphogenetic field evolution yielding from an initial population of undifferentiated cells to diversified unicellular organisms as well as specialized eukaryotic cell types. The cells are represented as Julia sets and Pickover biomorphs, simulating the effect of Darwinian natural selection with a simple genetic algorithm. The morphogenetic field “defines” the locations where cells are differentiated or sub-cellular components (or organelles) become organized. It may be realized by different possibilities, one of them by diffusing chemicals along the Turing model. We found that Pickover cells show a higher diversity of size and form than those populations evolved as Julia sets. Another novelty is the way that cellular organelles and cell nucleus fill in the cell, always in dependence on the previous cell definition as Julia set or Pickover biomorph. Our findings support the existence of specific attractors representing the functional and stable form of a differentiated cell—genuine cellular bauplans. The configuration of the morphogenetic field is “attracted” towards one or another attractor depending on the environmental influences as modeled by a particular fitness function. The model promotes the classical discussions of D’Arcy Thompson and the more recent views of Waddington, Goodwin and others that consider organisms as dynamical systems that evolve through a ‘master plan’ of transformations, amenable to natural selection. Intriguingly, the model also connects with current developments on mechanobiology, highlighting the informational–developmental role that cytoskeletons may play.

The Evolution of Meiosis From Mitosis

accounted for. We next ask what selective pressures might have favored the acquisition of homolog synapsis. The conclusion is surprising: the initial function of chromosome pairing was to limit, not enhance, recombination. Finally, we review the evidence that much of the molecular machinery required for the initial forms of homolog pairing probably existed in proto-eukaryote unicellular forms prior to the evolution of meiosis and therefore could have been readily ‘‘recruited’’ for the new role. Some experimental tests of the hypothesis are proposed.

Aspergillus terreuscomplex

Aspergillus terreus can cause invasive infections in humans, which are often refractory to therapy with the antifungal drug amphotericin B and have a propensity to dissemination. The organism has diverse colony morphology, and sub-typing studies have demonstrated that isolates of A. terreus are diverse in their genotypes. However, detailed phylogenetic studies of section Terrei employing sequence information from protein coding regions have not been thus far attempted. Interestingly, A. terreus produces unicellular forms called accessory conidia in vitro and during infection; the clinical relevance of these structures are not well understood. This paper presents an overview of the morphology, species identification strategies, and molecular epidemiology of A. terreus.

Algas perifíticas em dois ambientes do baixo rio Doce (lagoa Juparanã e rio Pequeno – Linhares, Estado do Espírito Santo, Brasil): variação espacial e temporal

This research aimed to evaluate the spatial and temporal variation of the periphytic algae community within two environments of the lower Doce River: Juparanã Lagoon and Pequeno River. Samplings were carried out every three months from August 2004 to May 2005 at both sites. Natural substrata of Eichhornia azurea (Sw.) Kunth petioles were collected from the sites. The community was analyzed according to species richness, frequency of occurrence, density of organisms, abundance and dominancy. Eighty-six taxa were recorded in the lagoon, and the density of organisms varied from 20,595 ind cm-2 (May/05) to 88,712 ind cm-2 (Nov/04). Eighty-three taxa were recorded in the river, and the density of organisms varied from 16,049 ind cm-2 (Feb/05) to 71,663 ind cm-2 (Aug/04). At both sites, the classes that predominated qualitatively were Cyanophyceae, Bacillariophyceae and Zygnemaphyceae, in which filamentous and unicellular forms dominated, followed by colonial forms. Quantitatively, the most representative classes were Cyanophyceae and Bacillariophyceae. A spatial variation was not observed. Precipitation, water temperature, electric conductivity and transparency were the variables that most oscillated according to seasonal variation (dry or rainy season). They also presented a greater number of significant correlations with the biological variables, showing evidence of temporal heterogeneity.

Evolution of SET-domain protein families in the unicellular and multicellular Ascomycota fungi

BackgroundThe evolution of multicellularity is accompanied by the occurrence of differentiated tissues, of organismal developmental programs, and of mechanisms keeping the balance between proliferation and differentiation. Initially, the SET-domain proteins were associated exclusively with regulation of developmental genes in metazoa. However, finding of SET-domain genes in the unicellular yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe suggested that SET-domain proteins regulate a much broader variety of biological programs. Intuitively, it is expected that the numbers, types, and biochemical specificity of SET-domain proteins of multicellular versus unicellular forms would reflect the differences in their biology. However, comparisons across the unicellular and multicellular domains of life are complicated by the lack of knowledge of the ancestral SET-domain genes. Even within the crown group, different biological systems might use the epigenetic 'code' differently, adapting it to organism-specific needs. Simplifying the model, we undertook a systematic phylogenetic analysis of one monophyletic fungal group (Ascomycetes) containing unicellular yeasts, Saccharomycotina (hemiascomycetes), and a filamentous fungal group, Pezizomycotina (euascomycetes).ResultsSystematic analysis of the SET-domain genes across an entire eukaryotic phylum has outlined clear distinctions in the SET-domain gene collections in the unicellular and in the multicellular (filamentous) relatives; diversification of SET-domain gene families has increased further with the expansion and elaboration of multicellularity in animal and plant systems. We found several ascomycota-specific SET-domain gene groups; each was unique to either Saccharomycotina or Pezizomycotina fungi. Our analysis revealed that the numbers and types of SET-domain genes in the Saccharomycotina did not reflect the habitats, pathogenicity, mechanisms of sexuality, or the ability to undergo morphogenic transformations. However, novel genes have appeared for functions associated with the transition to multicellularity. Descendents of most of the SET-domain gene families found in the filamentous fungi could be traced in the genomes of extant animals and plants, albeit as more complex structural forms.ConclusionSET-domain genes found in the filamentous species but absent from the unicellular sister group reflect two alternative evolutionary events: deletion from the yeast genomes or appearance of novel structures in filamentous fungal groups. There were no Ascomycota-specific SET-domain gene families (i.e., absent from animal and plant genomes); however, plants and animals share SET-domain gene subfamilies that do not exist in the fungi. Phylogenetic and gene-structure analyses defined several animal and plant SET-domain genes as sister groups while those of fungal origin were basal to them. Plants and animals also share SET-domain subfamilies that do not exist in fungi.

Physiological comparison between colonial and unicellular forms of Microcystis aeruginosa Kütz. (Cyanobacteria)

Z-X. Wu and L-R. Song. 2007. Physiological comparison between colonial and unicellular forms of Microcystis aeruginosa Kütz. (Cyanobacteria). Phycologia 47: 98–104. DOI: 10.2216/07–36.1In order to gain insight into the bloom sustainment of colonial Microcystis aeruginosa Kütz., physiological characterizations were undertaken in this study. Compared with unicellular Microcystis, colonial Microcystis phenotypes exhibited a higher maximum photosynthetic rate (Pm), a higher maximum electron transfer rate (ETRmax), higher phycocyanin content, and a higher affinity for inorganic carbon (K0.5 DIC ≤ 8.4 ± 0.7 µM) during the growth period monitored in this study. This suggests that photosynthetic efficiency is a dominant physiological adaptation found in colonial Microcystis, thus promoting bloom sustainment. In addition, the high content of soluble and total carbohydrates in colonial Microcystis suggests that this phenotype may possess a higher ability to tolerate enhanced stress conditions when compared to unicellular (noncolonial) phenotypes. Therefore, high photosynthetic activities and high tolerance abilities may explain the bloom sustainment of colonial Microcystis in eutrophic lakes.

Reconstructing the early evolution of Fungi using a six-gene phylogeny

The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species. Our results indicate that there may have been at least four independent losses of the flagellum in the kingdom Fungi. These losses of swimming spores coincided with the evolution of new mechanisms of spore dispersal, such as aerial dispersal in mycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.

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BioTechniquesVol. 39, No. 2 WebWatchOpen AccessWebWatchKevin AhernKevin AhernSearch for more papers by this authorPublished Online:30 May 2018https://doi.org/10.2144/05392WW01AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInRedditEmail Science BeatThink science. Think news. Think topical. Think images that jump off the screen and you're thinking Sciencentral. Billing itself as an “independent source for the latest news on science and technology,” Sciencentral is a leading site for online science news, views, and reviews. On the opening page, as this was written, one can read about sexuality genes in flies, participate in surveys (“should the FDA approve a drug on the basis of race?”), learn how to make “puffier” popcorn, and download the image of the week. Subtopic headings (Life Sciences, Physical Sciences, and Technology) provide avenues to information specific for these areas. A simply catch phrase at the top of the opening page probably describes the site best—”Making Sense of Science.”www.sciencentral.comDiseased OutlookTaking a VERY broad view of medicine and disease, the Diseases Database is a comprehensive medical resource aimed at a broader audience than hypochondriacs staring at a browser. Created for physicians, healthcare workers, and students in health professions, the Diseases Database provides a database of links from A to Z on topics (directly and peripherally) related to medicine. Information is organized simply. Visitors find what they're after via a simple search engine interface or by clicking on an alphabetical listing. Whether you want to learn more about symptoms/signs, inherited diseases, drugs/medications, or just simply general information about the biochemistry of disease. Diseases Database is a great place to start.www.diseasesdatabase.comOnline Bio BookGo to a publisher. Propose a book encompassing molecular biology, bioethics, bioengineering, cell biology, bioinformatics, biomedicine, biodiversity, and biocareers, and they'll probably politely smile and quickly escort you out the door. Take the same idea to the web, and you've got BioTeach, a fun-to-read educational site that covers all of these topics and more. With information organized under the subheadings described above and further subdivided into chapters, BioTeach abounds with well-written articles on diverse topics that would never make their way into a single textbook.bioteach.ubc.caSlimy CharactersThe slime molds ought to sue for slander. Some of the most misnamed organisms on the planet, many of them are neither very slimy nor very moldy. Their life cycle includes both unicellular and multicellular aspects, and it is for this reason, as well as their simple developmental cycle, that slime molds are popular model organisms of developmental biologists. When food becomes limiting, the unicellular form sends out chemical signals that lead to aggregation of neighboring cells, differentiation, and sporulation. Growth of the spores then leads to new unicellular forms. The DictyBase site, headed by Rex Chisholm and supported by the National Institutes of Health (NIH), serves as a one stop shop for researchers working on Dictyostelium discoideum, the most studied of the various slime molds. From pictures and videos to job opportunities and genomic sequence access, DictyBase is a must for anyone interested in slime molds.dictybase.orgLife's BranchesCan any simple web site accurately portray the diversity of life on Earth in a few pages? Certainly not, but the Tree of Life Web Project, hosted at the University of Arizona is not, by anyone's reckoning, a simple web site. With over 4000 pages of text, data, and pictures, the project makes a valiant effort to span this vast domain, and it does a pretty darn credible job. The Tree of Life's approach is collaborative in nature, with stories provided by biologists from all over the world. Encompassing biological diversity, evolutionary relationships, and dazzling images, information is diverse, well written, and definitely worth a read. The site's strong focus on education (for students and educators) and its intuitive design that provides easy access to information, make it a must see for anyone interested in biology education.tolweb.org/treeFiguresReferencesRelatedDetailsCited ByGender Diversity in the Board Room & Its Impacts: Is the Example of Norway a Way Forward?SSRN Electronic Journal Vol. 39, No. 2 Follow us on social media for the latest updates Metrics Downloaded 97 times History Published online 30 May 2018 Published in print August 2005 Information© 2005 Author(s)PDF download