Carcinoma is to Embryology as Mutation is to Genetics

Experiments are reviewed that indicate embryonic fields arecapable of regulating the neoplastic attributes of their closelyrelated carcinomas. In the case of blastocyst regulation ofembryonal carcinoma cells the reaction is mediated by contactof the cancer cells with trophectodermal cells in the presenceof blastocele fluid. In the case of regulation of melanoma,the reaction is mediated in the embryonic skin at the time normalmelanocytes migrate into it. A diffusible factor that inhibitscell division and seems to affect differentiation is involved.In the case of neuroblastoma, a degree of regulation is demonstrablein the neural crest migratory pathway, but the maximal effectis found in the adrenal, renal, and testicular primordia. Afactor inhibitory of mitosis for adenocarcinoma of the breastcan be demonstrated in the breast primordium. It is concludedthat there must be an embryonic field capable of regulatingevery kind of carcinoma: understanding of the phenomena maylead to a noncytotoxic cure for carcinoma, and through the useof cancer cells as probes of embryonic development to an understandingof embryonic induction.     

<Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>: a model to monitor bacterial air quality

Background

Low environmental air quality is a significant cause of mortality and morbidity and this question is now emerging as a main concern of governmental authorities. Airborne pollution results from the combination of chemicals, fine particles, and micro-organisms quantitatively or qualitatively dangerous for health or for the environment. Increasing regulations and limitations for outdoor air quality have been decreed in regards to chemicals and particles contrary to micro-organisms. Indeed, pertinent and reliable tests to evaluate this biohazard are scarce. In this work, our purpose was to evaluate the Caenorhaditis elegans killing test, a model considered as an equivalent to the mouse acute toxicity test in pharmaceutical industry, in order to monitor air bacterial quality.

Findings

The present study investigates the bacterial population in dust clouds generated during crop ship loading in harbor installations (Rouen harbor, Normandy, France). With a biocollector, airborne bacteria were impacted onto the surface of agar medium. After incubation, a replicate of the colonies on a fresh agar medium was done using a velvet. All the replicated colonies were pooled creating the "Total Air Sample". Meanwhile, all the colonies on the original plate were isolated. Among which, five representative bacterial strains were chosen. The virulence of these representatives was compared to that of the "Total Air Sample" using the Caenorhaditis elegans killing test. The survival kinetic of nematodes fed with the "Total Air Sample" is consistent with the kinetics obtained using the five different representatives strains.

Conclusions

Bacterial air quality can now be monitored in a one shot test using the Caenorhaditis elegans killing test.

     

Development of a new quantitative gas permeability method for dental implant-abutment connection tightness assessment

Background  

Most dental implant systems are presently made of two pieces: the implant itself and the abutment. The connection tightness between those two pieces is a key point to prevent bacterial proliferation, tissue inflammation and bone loss. The leak has been previously estimated by microbial, color tracer and endotoxin percolation.     

Representing "The World Boiled Down"

Museums are object-rich environments through which very diverse audiences move. When teams of scholars, museum educators, and exhibit designers translate research into museum exhibitions, what ways of seeing do they (un)intentionally encourage, challenge, or disrupt? When representing historic paradigms through museum media, what are the most effective ways to stimulate reflection and critique? These questions are raised in this review of the book 1001 Curious Things: Ye Olde Curiosity Shop and Native American Art and the Washington State History Museum exhibit of the same name.
The book and exhibit reviewed here invite us to peer through the windows of a Seattle curio shop to note particular aspects of early-20th-century Northwest Coast and Native Alaskan artifact trade. We learn how Ye Olde Curiosity Shop was a powerful mediator of public perception of indigenous peoples and an unexpected source of artifacts for notable ethnographic collections worldwide.     

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

Background

Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species.

Results

We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments).

Conclusions

The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment.     

Phylogenetic analysis using insertion sequence fingerprinting in Escherichia coli

Chromosomal DNA from 23 closely related, pathogenic strains of Escherichia coli was digested and probed for the insertion sequences IS1, IS2, IS4, IS5, and IS30. Under the assumption that elements residing in DNA restriction fragments of the same apparent length are identical by descent, parsimony analysis of these characters yielded a unique phylogenetic tree. This analysis not only distinguished among bacterial strains that were otherwise identical in their biochemical characteristics and enzyme electrophoretic mobilities, but certain aspects of the topology of the tree were consistent across several unrelated insertion elements. The distribution of IS elements was then reexamined in light of the inferred phylogenetic relationships to investigate the biological properties of the elements, such as rates of insertion and deletion, and to discover apparent recombinational events. The analysis shows that the pattern of distribution of insertion elements in the bacterial genome is sufficiently stable for epidemiological studies. Although the rate of recombination by conjugation has been postulated to be low, at least two such events appear to have taken place.