title: Seasonal and spatial variations in bacterial communities from tetrodotoxin-bearing and non-tetrodotoxin-bearing clams

authors: Biessy, Laura

subjects: Science & Technology

abstract: Tetrodotoxin (TTX) is one of the most potent naturally occurring compounds and is responsible for many human intoxications worldwide. Paphies australis are endemic clams to New Zealand which contain varying concentrations of TTX. Research suggests that P. australis accumulate the toxin exogenously, but the source remains uncertain. The aim of this study was to identify potential bacterial TTX-producers by exploring differences in bacterial communities in two organs of P. australis: the siphon and digestive gland. Samples from the digestive glands of a non-toxic bivalve Austrovenus stutchburyi that lives amongst toxic P. australis populations were also analyzed. Bacterial communities were characterized using 16S ribosomal RNA gene metabarcoding in P. australis sourced monthly from the Hokianga Harbor, a site known to have TTX-bearing clams, for 1 year, from ten sites with varying TTX concentrations around New Zealand, and in A. stutchburyi from the Hokianga Harbor. Tetrodotoxin was detected in P. australis from sites all around New Zealand and in all P. australis collected monthly from the Hokianga Harbor. The toxin averaged 150 μg kg–1 over the year of sampling in the Hokianga Harbor but no TTX was detected in the A. stutchburyi samples from the same site. Bacterial species diversity differed amongst sites (p < 0.001, F = 5.9) and the diversity in siphon samples was significantly higher than in digestive glands (p < 0.001, F = 65.8). Spirochaetaceae (4–60%) and Mycoplasmataceae (16–78%) were the most abundant families in the siphons and the digestive glands, respectively. The bacterial communities were compared between sites with the lowest TTX concentrations and the Hokianga Harbor (site with the highest TTX concentrations), and the core bacterial communities from TTX-bearing individuals were analyzed. The results from both spatial and temporal studies corroborate with previous hypotheses that Vibrio and Bacillus could be responsible for the source of TTX in bivalves. The results from this study also indicate that marine cyanobacteria, in particular picocyanobacteria (e.g., Cyanobium, Synechococcus, Pleurocapsa, and Prochlorococcus), should be investigated further as potential TTX producers.

text: Seasonal and spatial variations in bacterial communities from tetrodotoxin-bearing and non-tetrodotoxin-bearing clams Tetrodotoxin (TTX) is one of the most potent naturally occurring compounds and is responsible for many human intoxications worldwide. Paphies australis are endemic clams to New Zealand which contain varying concentrations of TTX. Research suggests that P. australis accumulate the toxin exogenously, but the source remains uncertain. The aim of this study was to identify potential bacterial TTX-producers by exploring differences in bacterial communities in two organs of P. australis: the siphon and digestive gland. Samples from the digestive glands of a non-toxic bivalve Austrovenus stutchburyi that lives amongst toxic P. australis populations were also analyzed. Bacterial communities were characterized using 16S ribosomal RNA gene metabarcoding in P. australis sourced monthly from the Hokianga Harbor, a site known to have TTX-bearing clams, for 1 year, from ten sites with varying TTX concentrations around New Zealand, and in A. stutchburyi from the Hokianga Harbor. Tetrodotoxin was detected in P. australis from sites all around New Zealand and in all P. australis collected monthly from the Hokianga Harbor. The toxin averaged 150 μg kg–1 over the year of sampling in the Hokianga Harbor but no TTX was detected in the A. stutchburyi samples from the same site. Bacterial species diversity differed amongst sites (p < 0.001, F = 5.9) and the diversity in siphon samples was significantly higher than in digestive glands (p < 0.001, F = 65.8). Spirochaetaceae (4–60%) and Mycoplasmataceae (16–78%) were the most abundant families in the siphons and the digestive glands, respectively. The bacterial communities were compared between sites with the lowest TTX concentrations and the Hokianga Harbor (site with the highest TTX concentrations), and the core bacterial communities from TTX-bearing individuals were analyzed. The results from both spatial and temporal studies corroborate with previous hypotheses that Vibrio and Bacillus could be responsible for the source of TTX in bivalves. The results from this study also indicate that marine cyanobacteria, in particular picocyanobacteria (e.g., Cyanobium, Synechococcus, Pleurocapsa, and Prochlorococcus), should be investigated further as potential TTX producers.

year: 2020

title: Remarkable simple fabrication of superhydrophobic surfaces using electroless galvanic deposition

authors: Larmour, Iain A.

subjects: hydrophobic effect

abstract: Much of the recent research on hydrophobic materials has been inspired by the water-repellent nature of lotus leaves (Nelumbo nucifera and N. lutea), which show a double roughness on their surfaces (nanohairs on microbumps) along with a waxy coating.

text: Remarkable simple fabrication of superhydrophobic surfaces using electroless galvanic deposition Much of the recent research on hydrophobic materials has been inspired by the water-repellent nature of lotus leaves (Nelumbo nucifera and N. lutea), which show a double roughness on their surfaces (nanohairs on microbumps) along with a waxy coating.

year: 2007

title: Ideology is theft: Thoughts on the legitimacy of a Maori psychology

authors: Tamatea, Armon J.

subjects: Maori

abstract: ‘War, in fact, can be seen as a process of achieving equilibrium among unequal technologies’ (McLuhan, 1964) 
We are at war. As Western science and its accompanying technology expands the frontiers of knowledge at an ever-increasing rate, ‘indigenous’ perspectives of knowledge are exiled into the borderlands of special interest groups and localized research programmes. Mainstream scientific thought lays claim to objective interpretations of experience at the expense of alternative realities offered by emerging theories of knowledge. Furthermore, as localized worldviews (i.e., those derived from ancestral knowledge bases and pre-industrial or non-scientific premises) challenge existing paradigms, the inevitable interactions threaten to undermine the fidelity of this knowledge. One such arena where this ideological conflict is apparent is the growing field of Maori psychology.

text: Ideology is theft: Thoughts on the legitimacy of a Maori psychology ‘War, in fact, can be seen as a process of achieving equilibrium among unequal technologies’ (McLuhan, 1964) 
We are at war. As Western science and its accompanying technology expands the frontiers of knowledge at an ever-increasing rate, ‘indigenous’ perspectives of knowledge are exiled into the borderlands of special interest groups and localized research programmes. Mainstream scientific thought lays claim to objective interpretations of experience at the expense of alternative realities offered by emerging theories of knowledge. Furthermore, as localized worldviews (i.e., those derived from ancestral knowledge bases and pre-industrial or non-scientific premises) challenge existing paradigms, the inevitable interactions threaten to undermine the fidelity of this knowledge. One such arena where this ideological conflict is apparent is the growing field of Maori psychology.

year: 2008