title: Depuration of tetrodotoxin and changes in bacterial communities in Pleurobranchea maculata adults and egg masses maintained in captivity

authors: Wood, Susanna A.

subjects: chemical defense

abstract: Depuration of tetrodotoxin (TTX) was investigated in adult grey side-gilled sea slugs, Pleurobranchaea maculata, maintained in captivity on a TTX-free diet. Three adults were harvested every 21 days for 126 days, and TTX concentrations were measured in organs/tissues and egg masses. Automated rRNA intergenic spacer analysis (ARISA) was used to investigate bacterial community structure in selected samples. Linear modeling of adult data demonstrated a decline (P < 0.001) in average total TTX concentrations over time. Temporal data obtained from a wild population showed similar depuration rates, indicating that once adults reach a certain size, or sexual maturity, TTX is no longer produced or acquired substantially. Depuration rates differed among organs, with concentrations in the heart declining the fastest. The gonads had the slowest and least significant depuration rate indicating, at most, weak depuration of this tissue. There was a strong correlation (R (2) = 0.66) between TTX concentrations in the first-laid egg masses and total TTX in the corresponding adult. These data suggest that adult P. maculata transfer TTX to their offspring, and presumably that functions as a chemical defense. ARISA data showed a shift in bacterial community structure within 3 weeks of introduction to captivity. Based on the combined data, the exact origin of TTX in P. maculata is unclear, with evidence both in favor and against a dietary source, and endogenous or bacterial production.

text: Depuration of tetrodotoxin and changes in bacterial communities in Pleurobranchea maculata adults and egg masses maintained in captivity Depuration of tetrodotoxin (TTX) was investigated in adult grey side-gilled sea slugs, Pleurobranchaea maculata, maintained in captivity on a TTX-free diet. Three adults were harvested every 21 days for 126 days, and TTX concentrations were measured in organs/tissues and egg masses. Automated rRNA intergenic spacer analysis (ARISA) was used to investigate bacterial community structure in selected samples. Linear modeling of adult data demonstrated a decline (P < 0.001) in average total TTX concentrations over time. Temporal data obtained from a wild population showed similar depuration rates, indicating that once adults reach a certain size, or sexual maturity, TTX is no longer produced or acquired substantially. Depuration rates differed among organs, with concentrations in the heart declining the fastest. The gonads had the slowest and least significant depuration rate indicating, at most, weak depuration of this tissue. There was a strong correlation (R (2) = 0.66) between TTX concentrations in the first-laid egg masses and total TTX in the corresponding adult. These data suggest that adult P. maculata transfer TTX to their offspring, and presumably that functions as a chemical defense. ARISA data showed a shift in bacterial community structure within 3 weeks of introduction to captivity. Based on the combined data, the exact origin of TTX in P. maculata is unclear, with evidence both in favor and against a dietary source, and endogenous or bacterial production.

year: 2012

title: Responses of salmonids to habitat changes

authors: Hicks, Brendan J.

subjects: biology

abstract: Streams in western North America provide spawning and rearing habitats for several species of salmon and trout that are of substantial economic importance in the region. Timber that grows on lands through which these streams flow is also economically important, and its harvest can substantially change habitat conditions and aquatic production in salmonid streams. Undisturbed forests, the streams that flow through them, and the salmonid communities in these streams have intrinsic scientific, genetic, and cultural values in addition to their economic importance. The complex relations between salmonids and their physical environment, and the changes in these relations brought about by timber harvest, have been investigated extensively (see the bibliography by Macdonald et al. 1988). However, in spite of considerable evidence of profound changes in channel morphology and in light, temperature, and flow regimes associated with timber harvests, much uncertainty exists about the responses of salmonids to these changes.

text: Responses of salmonids to habitat changes Streams in western North America provide spawning and rearing habitats for several species of salmon and trout that are of substantial economic importance in the region. Timber that grows on lands through which these streams flow is also economically important, and its harvest can substantially change habitat conditions and aquatic production in salmonid streams. Undisturbed forests, the streams that flow through them, and the salmonid communities in these streams have intrinsic scientific, genetic, and cultural values in addition to their economic importance. The complex relations between salmonids and their physical environment, and the changes in these relations brought about by timber harvest, have been investigated extensively (see the bibliography by Macdonald et al. 1988). However, in spite of considerable evidence of profound changes in channel morphology and in light, temperature, and flow regimes associated with timber harvests, much uncertainty exists about the responses of salmonids to these changes.

year: 1991

title: Maori and psychology: Indigenous psychology in New Zealand

authors: Nikora, Linda Waimarie

subjects: Maori

abstract: Maori have their own approaches to health and well-being, which stem from a world view that values balance, continuity, unity and purpose. The world view is not typically thought of as 'psychology', yet it is a foundation for shared understandings and intelligible action among Maori. Maori behaviours, values, ways of doing things and understandings are often not visible nor valued. However, through these opening years of the twenty-first century, psychologists are slowly turning their attention to addressing this invisibility with the explicit agenda of building 'indigenous psychologies'

text: Maori and psychology: Indigenous psychology in New Zealand Maori have their own approaches to health and well-being, which stem from a world view that values balance, continuity, unity and purpose. The world view is not typically thought of as 'psychology', yet it is a foundation for shared understandings and intelligible action among Maori. Maori behaviours, values, ways of doing things and understandings are often not visible nor valued. However, through these opening years of the twenty-first century, psychologists are slowly turning their attention to addressing this invisibility with the explicit agenda of building 'indigenous psychologies'

year: 2007