Scale Model of a Soil Aggregate and Associated Organisms: A Teaching Tool for Soil Ecology

Soil is a complex habitat for diverse biota. A significant challenge in teaching soil ecology is our inability to observe organisms as they live and interact in the soil. The objective of this article is to describe an interactive class project to help students visualize the sizes of different groups of soil organisms and to relate these to soil structural components. This project was carried out by students in an upper-level undergraduate soil ecology class. It involved the design and construction of a 4000× scale model of a soil aggregate and its associated organisms. The body of the model was made from inexpensive, lightweight materials and had a diameter of approximately 1 m to depict a 0.25-mm aggregate. Students identified and discussed appropriate size ranges and construction materials for the model’s bacteria, fungi, nematodes, mites, springtails, and other components. Instructor-guided questions addressed size and arrangement of sand, silt, and clay particles; pores; and organic matter in a typical soil aggregate. The model is a useful tool for conveying physical and ecological relationships among soil organisms and is adaptable for use at diverse educational levels

Effects Of The Deepwater Horizon Oil Spill On Coastal Marshes And Associated Organisms

Oil gushed from the Macondo Mississippi Canyon 252 well into the Gulf of Mexico for 87 days after the Deepwater Horizon drilling rig exploded and sank. A concern, after widespread dispersant use offshore on surface waters and at the wellhead, was that the oil/dispersant mixture would reach valuable, and vulnerable, coastal ecosystems. Standardized oil spill response methodology identified 1,773 km of the 7,058 km of surveyed shoreline as oiled, with 1,075 km oiled in Louisiana. This paper synthesizes key results of published research on the oiling effects on coastal habitats and their inhabitants from microbes to vertebrates. There were immediate negative impacts in the moderately to heavily oiled marshes, and on the resident fish and invertebrates. Recovery occurred in many areas within the two years following the oiling and continues, but permanent damage from heavily oiled marshes resulted in eroded shorelines. Organisms, including microbial communities, invertebrates, and vertebrates, were diminished by acute and chronic hydrocarbon exposure. However, the inherent variability in populations and levels of exposure, compounded with multiple stressors, often masked what were expected, predictable impacts. The effects are expected to continue to some degree with legacy hydrocarbons, or the marsh ecosystem will reach a new baseline condition in heavily damaged areas

Clinical microbial laboratory investigation

Microorganisms universally attach to surfaces and produce extracellular polysaccharides, resulting in the formation of a biofilm. Biofilms pose a serious problem for public health because of the increased resistance of biofilm-associated organisms to antimicrobial agents and the potential for these organisms to cause infections in patients with indwelling medical devices. The roles of biofilms in infection, including the bloodstream and urinary tract infections, will be presented in this talk. The various collection methods for sampling and transporting biofilm-associated organisms will also be shared in the presentation. In summary, this talk provides a clear understanding on the roles and physiological aspects of biofilms that would enhance the clinical decision-making process

The plant-pathogen haustorial interface at a glance

Many filamentous pathogens invade plant cells through specialized hyphae called haustoria. These infection structures are enveloped by a newly synthesized plant-derived membrane called the extrahaustorial membrane (EHM). This specialized membrane is the ultimate interface between the plant and pathogen, and is key to the success or failure of infection. Strikingly, the EHM is reminiscent of host-derived membrane interfaces that engulf intracellular metazoan parasites. These perimicrobial interfaces are critical sites where pathogens facilitate nutrient uptake and deploy virulence factors to disarm cellular defenses mounted by their hosts. Although the mechanisms underlying the biogenesis and functions of these host-microbe interfaces are poorly understood, recent studies have provided new insights into the cellular and molecular mechanisms involved. In this Cell Science at a Glance and the accompanying poster, we summarize these recent advances with a specific focus on the haustorial interfaces associated with filamentous plant pathogens. We highlight the progress in the field that fundamentally underpin this research topic. Furthermore, we relate our knowledge of plant-filamentous pathogen interfaces to those generated by other plant-associated organisms. Finally, we compare the similarities between host-pathogen interfaces in plants and animals, and emphasize the key questions in this research area

Survey of Oyster Diseases in the Galveston Bay Area - Survey of Oyster Populations and Associated Organisms

Moralities among tray-held oysters (Crassostrea virginica) were studied during a two year period at stations located on Switchover Reef and Hannah Reef. In 1963 moralities at both stations showed similar patterns, increasing during the summer months (with peaks in August-September) and declining during the fall and winter. The summer moralities were associated with high infections of Dermocystidium marinum. From March through December 1963 oysters at the Switch over station suffered a mortality of 52.6%. From April through December, 1963 a mortality of 42.2% occurred among the Hanna oysters

Epizootiology of diseases of oysters (Crassostrea virginica), and parasites of associated organisms in eastern North America

Haplosporidan parasites of oysters have been reported from four continents. Those of the genera Minchinia, Haplosporidium, and Marteilia, which cause serious diseases of oysters, have been intensively studied. Epizootiology of these highly pathogenic species is well known. Life cycles are obscure for all haplosporidans because artificial infections have not been achieved. The high pathogenicity of newly-discovered haplosporidan diseases to native oysters in eastern North America and western Europe may rod:care that these are exohc pathogens paras~t:zmg suscephble oysters not previously exposed to these disease agents. Epizootiology of two haplosporidan pathogens along the middle Atlantic Coast of North America during 25 years of disease activity is discussed. Haplosporidiurn nelsoni sporulates only rarely and its life cycle remains unconfirmed. Resistant oysters were developed in nature and from laboratory breeding. Haplosporidium costale which causes \u27Seaside Disease in high-salinity waters appears to be a more acclimated disease with regular patterns of infection and mortality. Several minor parasites whose life cycles and host species need more study are mentioned

Genomic analysis of serogroup Y Neisseria meningitidis isolates reveals extensive similarities between carriage and disease-associated organisms

Background. Neisseria meningitidis is a frequent colonizer of the human nasopharynx with asymptomatic carriage providing the reservoir for invasive, disease-causing strains. Serogroup Y (MenY) strains are a major cause of meningococcal disease. High resolution genetic analyses of carriage and disease isolates can establish epidemiological relationships and identify potential virulence factors. Methods. Whole genome sequence data were obtained from UK MenY carriage isolates from 1997-2010 (n=99). Sequences were compared to those from MenY invasive isolates from 2010 and 2011 (n=73) using a gene-by-gene approach. Results. Comparisons across 1,605 core genes resolved 91% of isolates into one of eight clusters containing closely related disease and carriage isolates. Six clusters contained carried meningococci isolated in 1997-2001 suggesting temporal stability. One cluster of isolates, predominately sharing the designation Y: P1.5-1,10-1: F4-1: ST-1655 (cc23), was resolved into a sub-cluster with 86% carriage isolates and a second with 90% invasive isolates. These subclusters were defined by specific allelic differences in five core genes encoding glycerate kinase (glxK), valine-pyruvate transaminase (avtA), superoxide dismutase (sodB) and two hypothetical proteins. Conclusions. High resolution genetic analyses detected long-term temporal stability and temporally-overlapping carriage and disease populations for MenY clones but also evidence of a disease-associated clone