Morphology of Proliferating Epithelial Cellular Tissue

We investigate morphologies of proliferating cellular tissue using a newly developed numerical simulation model for mechanical cell division. The model reproduces structures of simple multi-cellular organisms via simple rules for selective division and division plane orientation. The model is applied to a bimodal mixture of stiff cells with a low growth potential and soft cells with a high growth potential. In an even mixture, the soft cells develop into a tissue matrix and the stiff cells into a dendrite-like network structure. For soft cell inclusion in a stiff cellular matrix, the soft cells develop to a fast growing tumour like structure that gradually evacuates the stiff cell matrix. With increasing inter-cell friction, the tumour growth slows down and parts of it is driven to self-inflicted cell death

An Analysis of Diatom Growth Rate and the Implications for the Biodiesel Industry

The need for an economically-feasible, carbon-neutral fuel source rises as rates of carbon emissions increase and climate change persists. Diatom biodiesel is currently being researched as a carbon-neutral alternative to petroleum. Biochemical engineering, a method utilized to increase lipid accumulation in microalgae for harvest, works by stressing algal cultures in order to bias their metabolism towards lipid (fat) production. Although Nitrogen (N) is the most common limiting-nutrient in research, Silicon (Si) is also vital to diatom cell growth and division, and therefore its limitation would also cause an accumulation of lipids in cells. In fact, Si-limitation has yielded higher lipid content in diatoms than N-limitation without any of the severe physiological damage, making it a prime candidate for biochemical engineering of microalgae biodiesel. Two different species of diatom, Thalassiosira rotula and Coscinodiscus radiatus, were cultured and grown in a silicon- deficient media (20μM-Si) and in a silicon-rich media (80 μM-Si) to observe how differences in environmental Si affected frustule1 size, diatom growth rates, and lipid accumulation. We also stained the cells with dyes to observe Si frustules and lipid content, then took photographs with a fluorescent microscope for qualitative analysis. Our results suggested that diatom species had a greater impact on growth rate than Si treatment. Since all diatom species have different rates of growth, Si uptake and metabolism, it could be more prudent to focus on which species of diatom, rather than which nutrient-limitations, are best suited for biodiesel production

Cross Cultural Intervention: The Case of the Hexed Hair

One aspect of my work as Director of Education and Training at Hutchings Psychiatric Center is to consult on cases that are difficult for clinical staff. It is in these situations that my clinical sociological skills are used extensively. I wish to present an unusual case on which I was asked to consult in the Fall of 1986. I present this case with the permission of the client whom we shall call Sophie Koslowski.

High-resolution metagenomic reconstruction of the freshwater spring bloom

Background The phytoplankton spring bloom in freshwater habitats is a complex, recurring, and dynamic ecological spectacle that unfolds at multiple biological scales. Although enormous taxonomic shifts in microbial assemblages during and after the bloom have been reported, genomic information on the microbial community of the spring bloom remains scarce. Results We performed a high-resolution spatio-temporal sampling of the spring bloom in a freshwater reservoir and describe a multitude of previously unknown taxa using metagenome-assembled genomes of eukaryotes, prokaryotes, and viruses in combination with a broad array of methodologies. The recovered genomes reveal multiple distributional dynamics for several bacterial groups with progressively increasing stratification. Analyses of abundances of metagenome-assembled genomes in concert with CARD-FISH revealed remarkably similar in situ doubling time estimates for dominant genome-streamlined microbial lineages. Discordance between quantitations of cryptophytes arising from sequence data and microscopic identification suggested the presence of hidden, yet extremely abundant aplastidic cryptophytes that were confirmed by CARD-FISH analyses. Aplastidic cryptophytes are prevalent throughout the water column but have never been considered in prior models of plankton dynamics. We also recovered the first metagenomic-assembled genomes of freshwater protists (a diatom and a haptophyte) along with thousands of giant viral genomic contigs, some of which appeared similar to viruses infecting haptophytes but owing to lack of known representatives, most remained without any indication of their hosts. The contrasting distribution of giant viruses that are present in the entire water column to that of parasitic perkinsids residing largely in deeper waters allows us to propose giant viruses as the biological agents of top-down control and bloom collapse, likely in combination with bottom-up factors like a nutrient limitation. Conclusion We reconstructed thousands of genomes of microbes and viruses from a freshwater spring bloom and show that such large-scale genome recovery allows tracking of planktonic succession in great detail. However, integration of metagenomic information with other methodologies (e.g., microscopy, CARD-FISH) remains critical to reveal diverse phenomena (e.g., distributional patterns, in situ doubling times) and novel participants (e.g., aplastidic cryptophytes) and to further refine existing ecological models (e.g., factors affecting bloom collapse). This work provides a genomic foundation for future approaches towards a fine-scale characterization of the organisms in relation to the rapidly changing environment during the course of the freshwater spring bloom

Ścieśnienia końcowe w dialekcie kurpiowskim

Niniejszy artykuł omawia występowanie samogłosek ścieśnionych w systemie deklinacyjnym dialektu kurpiowskiego. Przedstawione wyniki oparte są na przeprowadzonych przeze mnie badaniach materiałowych we wsiach środkowego pasa regionu kurpiowskiego i dotyczą alternacji pomiędzy samogłoskami nieścieśnionymi a ścieśnionymi. Ścieśnienia zachodzą w końcowej sylabie rzeczowników przed spółgłoską dźwięczną, która może być albo obstruentem albo sonorantem. Analiza opisowych reguł przedstawiona jest w ramach derywacyjnej teorii optymalności.This article investigates the occurrence of tense vowels in Kurpian and reports on the results of my fieldwork conducted in the villages of central Kurpia. The article looks at declensional paradigms of nouns and concludes that lax vowels alternate with tense vowels when they are followed by a voiced consonant (an obstruent or a sonorant) at the end of the word. The descriptive generalizations are analysed formally in terms of Derivational Optimality Theory, a framework that is well equipped to handle the opacity unveiled by the Kurpian data

Lake water acidification and temperature have a lagged effect on the population dynamics of Isoëtes echinospora via offspring recruitment

The aquatic quillwort, Isoëtes echinospora, survived the strong water acidification during 1960s–1990s in Plešné Lake (Bohemian Forest, Central Europe), but failed to reproduce. We studied the relationships between a recent population recovery and an improvement of lake water quality. We used correlation analysis to evaluate lagged seasonal effects of lake water quality on population dynamics during the past decade, and factor analysis to determine the independent factors responsible for population recovery. We also provided a water-quality-based reconstruction of population growth from the beginning of the lake recovery two decades ago, using a partial least squares regression (PLSR) model of population growth. We identified three independent controlling factors: nutrients (nitrate, phosphorus, calcium, potassium, magnesium), stressors (pH, ionic aluminium) and temperature. Of these, nutrient availability did not limit the quillwort growth, but annual mean pH and winter mean concentrations of toxic ionic aluminium influenced population growth through negative effects on sporeling establishment until the age of one year, while cumulative temperature in spring and summer controlled the later plant growth. Thus, water quality in the acidified Plešné Lake mainly controls recruitment success rather than adult survival of Isoëtes echinospora. This study provides the first in situ evidence that the recruitment success, namely the annual increment in the adult quillwort population, indicates the degree of recovery from acidification, however further extensive investigation is required to more accurately quantify, and therefore understand, the relationships between recruitment, water quality and other factors

Common Presence of Phototrophic Gemmatimonadota in Temperate Freshwater Lakes

Members of the bacterial phylum Gemmatimonadota are ubiquitous in most natural environments and represent one of the top 10 most abundant bacterial phyla in soil. Sequences affiliated with Gemmatimonadota were also reported from diverse aquatic habitats; however, it remains unknown whether they are native organisms or represent bacteria passively transported from sediment or soil. To address this question, we analyzed metagenomes constructed from five freshwater lakes in central Europe. Based on the 16S rRNA gene frequency, Gemmatimonadota represented from 0.02 to 0.6% of all bacteria in the epilimnion and between 0.1 and 1% in the hypolimnion. These proportions were independently confirmed using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). Some cells in the epilimnion were attached to diatoms (Fragilaria sp.) or cyanobacteria (Microcystis sp.), which suggests a close association with phytoplankton. In addition, we reconstructed 45 metagenome-assembled genomes (MAGs) related to Gemmatimonadota. They represent several novel lineages, which persist in the studied lakes during the seasons. Three lineages contained photosynthesis gene clusters. One of these lineages was related to Gemmatimonas phototrophica and represented the majority of Gemmatimonadota retrieved from the lakes’ epilimnion. The other two lineages came from hypolimnion and probably represented novel photoheterotrophic genera. None of these phototrophic MAGs contained genes for carbon fixation. Since most of the identified MAGs were present during the whole year and cells associated with phytoplankton were observed, we conclude that they represent truly limnic Gemmatimonadota distinct from the previously described species isolated from soils or sediments

A Survey of the Taxonomy of the Cyanobacteria from Northeast Florida, Descriptions of Novel Taxa, and an Investigation into the Factors Which Influence the Epibenthic Cyanobacterial Community

Cyanobacteria are important components of the aquatic system, valued for their oxygen production, nitrogen fixation, and as the base of many aquatic food webs. This study investigated several aspects of cyanobacteria such as the diversity and response to nutrient enrichments. A survey of Northeast Florida was conducted between the years of 2010 and 2012; a total of 145 taxa were identified in freshwater habitats, such as springs, lakes, rivers, and retention ponds. While surveying the St. Johns River in Jacksonville, Florida, a novel Stigonematalean taxon was isolated and cultured. Subsequent morphological and genetic analyses indicate that this taxon is related to Fischerella, Nostochopsis, and Westelliopsis, though with poor bootstrap support. Thus, a new genus and species (Reptodigitus chapmanii gen. et sp. nov.) is proposed. Cyanobacterial community shifts are increasingly being employed as an indicator of ecosystem health. The last part of this study is an experimental manipulation of nutrients and subsequent community analyses. Chlorophyll a, total number of cells, and Dmax were significantly different between control groups and nutrient enriched groups. Phosphate was not strongly correlated to species richness, chlorophyll a, evenness, total number of cells, species richness, or diversity in either the control or the nutrient enriched groups. Nitrogen displayed similar results, though it was slightly more strongly correlated to evenness and diversity in the nutrient enriched group than the control group. The results of the survey and nutrient enrichment experiment are important parts of the investigation into how cyanobacterial communities respond to changes in nutrient concentrations, which can then be used to devise a standard metric against which water management agencies can compare to determine the health of a given aquatic system