Biomedical subjects

Catharine A Conley

Publications and source records attributed to Catharine A Conley.

5 recordsLinked to original sources

PubMed2006

A preliminary survey of non-lichenized fungi cultured from the hyperarid Atacama Desert of Chile.

The Atacama Desert is one of the driest environments on Earth, and has been so for over 200,000 years. Previous reports have suggested that surprisingly low numbers of culturable bacteria, counted as biomass or species diversity, are present in Atacama sands collected from the most hyperarid regions. In previous studies, the presence of eukaryotic organisms was not discussed. In this report, we describe a method of direct plating onto rich media that resulted in culturing a range of fungi from Atacama samples. All fungi identified in this preliminary survey are spore-forming saprobes that are readily dispersed by wind, a likely mechanism that accounts for their presence in the central Atacama Desert.

Chile↗

PubMed2006

Decreased expression of myogenic transcription factors and myosin heavy chains in Caenorhabditis elegans muscles developed during spaceflight.

The molecular mechanisms underlying muscle atrophy during spaceflight are not well understood. We have analyzed the effects of a 10-day spaceflight on Caenorhabditis elegans muscle development. DNA microarray, real-time quantitative PCR, and quantitative western blot analyses revealed that the amount of MHC in both body-wall and pharyngeal muscle decrease in response to spaceflight. Decreased transcription of the body-wall myogenic transcription factor HLH-1 (CeMyoD) and of the three pharyngeal myogenic transcription factors, PEB-1, CEH-22 and PHA-4 were also observed. Upon return to Earth animals displayed reduced rates of movement, indicating a functional defect. These results demonstrate that C. elegans muscle development is altered in response to spaceflight. This altered development occurs at the level of gene transcription and was observed in the presence of innervation, not simply in isolated cells. This important finding coupled with past observations of decreased levels of the same myogenic transcription factions in vertebrates after spaceflight raises the possibility that altered muscle development is a contributing factor to spaceflight-induced muscle atrophy in vertebrates.

Animals↗

PubMed2006

Delayed development and lifespan extension as features of metabolic lifestyle alteration in C. elegans under dietary restriction.

Studies of the model organism Caenorhabditis elegans have almost exclusively utilized growth on a bacterial diet. Such culturing presents a challenge to automation of experimentation and introduces bacterial metabolism as a secondary concern in drug and environmental toxicology studies. Axenic cultivation of C. elegans can avoid these problems, yet past work suggests that axenic growth is unhealthy for C. elegans. Here we employ a chemically defined liquid medium to culture C. elegans and find development slows, fecundity declines, lifespan increases, lipid and protein stores decrease, and gene expression changes relative to that on a bacterial diet. These changes do not appear to be random pathologies associated with malnutrition, as there are no developmental delays associated with starvation, such as L1 or dauer diapause. Additionally, development and reproductive period are fixed percentages of lifespan regardless of diet, suggesting that these alterations are adaptive. We propose that C. elegans can exist as a healthy animal with at least two distinct adult life histories. One life history maximizes the intrinsic rate of population increase, the other maximizes the efficiency of exploitation of the carrying capacity of the environment. Microarray analysis reveals increased transcript levels of daf-16 and downstream targets and past experiments demonstrate that DAF-16 (FOXO) acting on downstream targets can influence all of the phenotypes we see altered in maintenance medium. Thus, life history alteration in response to diet may be modulated by DAF-16. Our observations introduce a powerful system for automation of experimentation on healthy C. elegans and for systematic analysis of the profound impact of diet on animal physiology.

Animals↗

PubMed2005

Caenorhabditis elegans survives atmospheric breakup of STS-107, space shuttle Columbia.

The nematode Caenorhabditis elegans, a popular organism for biological studies, is being developed as a model system for space biology. The chemically defined liquid medium, C. elegans Maintenance Medium (CeMM), allows axenic cultivation and automation of experiments that are critical for spaceflight research. To validate CeMM for use during spaceflight, we grew animals using CeMM and standard laboratory conditions onboard STS-107, space shuttle Columbia. Tragically, the Columbia was destroyed while reentering the Earth's atmosphere. During the massive recovery effort, hardware that contained our experiment was found. Live animals were observed in four of the five recovered canisters, which had survived on both types of media. These data demonstrate that CeMM is capable of supporting C. elegans during spaceflight. They also demonstrate that animals can survive a relatively unprotected reentry into the Earth's atmosphere, which has implications with regard to the packaging of living material during space flight, planetary protection, and the interplanetary transfer of life.

Acceleration↗

PubMed2003

Chemically defined medium and Caenorhabditis elegans.

BACKGROUND: C. elegans has been established as a powerful genetic system. Use of a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of use in large-scale growth and screening of animals. RESULTS: We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats to using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change the composition of the defined medium. CONCLUSIONS: As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.

Adaptation, Physiological↗