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Culture optimization for the emergent zooplanktonic model organism Oikopleura dioica.

Bouquet JM, Spriet E, Troedsson C, Otterå H, Chourrout D, Thompson EM - J. Plankton Res. (2009)

Bottom Line: This urochordate, has a simplified anatomical organization, remains transparent throughout an exceptionally short life cycle of less than 1 week and exhibits high fecundity.At 70 Mb, the compact, sequenced genome ranks among the smallest known metazoan genomes, with both gene regulatory and intronic regions highly reduced in size.The organism occupies an important trophic role in marine ecosystems and is a significant contributor to global vertical carbon flux.

View Article: PubMed Central - PubMed

Affiliation: Sars International Centre for Marine Molecular Biology, Thormøhlensgate 55, N-5008 Bergen , Norway.

ABSTRACT
The pan-global marine appendicularian, Oikopleura dioica, shows considerable promise as a candidate model organism for cross-disciplinary research ranging from chordate genetics and evolution to molecular ecology research. This urochordate, has a simplified anatomical organization, remains transparent throughout an exceptionally short life cycle of less than 1 week and exhibits high fecundity. At 70 Mb, the compact, sequenced genome ranks among the smallest known metazoan genomes, with both gene regulatory and intronic regions highly reduced in size. The organism occupies an important trophic role in marine ecosystems and is a significant contributor to global vertical carbon flux. Among the short list of bona fide biological model organisms, all share the property that they are amenable to long-term maintenance in laboratory cultures. Here, we tested diet regimes, spawn densities and dilutions and seawater treatment, leading to optimization of a detailed culture protocol that permits sustainable long-term maintenance of O. dioica, allowing continuous, uninterrupted production of source material for experimentation. The culture protocol can be quickly adapted in both coastal and inland laboratories and should promote rapid development of the many original research perspectives the animal offers.

No MeSH data available.


Growth curves at 20°C under continuous illumination for algae used as food sources. Cell concentrations (C, cells mL−1) at times (T, days), were calculated from optical densities using the species specific equations defined in Fig. 2. Growth rates were determined using the equation K = (lnC2−lnC1)/(T2−T1): where K is the growth rate (days−1) and lnCx are the natural logarithms of cell concentrations at the time points Tx. The intersection points (arrows) of the broken lines with the growth curves indicate the lower (T1) and upper (T2) limits of the linear growth phases of the algal cultures that were used for feeding. Doubling times (T2, days) were calculated as T2 = ln2/K. Vertical bars indicate standard errors (N = 6).
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FBN132F3: Growth curves at 20°C under continuous illumination for algae used as food sources. Cell concentrations (C, cells mL−1) at times (T, days), were calculated from optical densities using the species specific equations defined in Fig. 2. Growth rates were determined using the equation K = (lnC2−lnC1)/(T2−T1): where K is the growth rate (days−1) and lnCx are the natural logarithms of cell concentrations at the time points Tx. The intersection points (arrows) of the broken lines with the growth curves indicate the lower (T1) and upper (T2) limits of the linear growth phases of the algal cultures that were used for feeding. Doubling times (T2, days) were calculated as T2 = ln2/K. Vertical bars indicate standard errors (N = 6).

Mentions: To examine growth rates of the algal strains, cultures were inoculated with an initial cell density of 2.5×104 cells mL−1. Sampling for optical density measurement was carried out twice on the first day and then once per day thereafter (Fig. 3). Growth rates (K) and doubling times (T2) during the linear portion of the exponential growth curves were calculated as indicated in the figure legend. Cell densities of Isochrysis sp. and C. calcitrans increased rapidly with a minor lag phase, whereas R. reticulata grew less rapidly. For routine use in the feeding of O. dioica, minimum cell densities of 1×106 cells mL−1 were reached after 48 h for Isochrysis and 72 h for C. calcitrans. For R. reticulata, a minimum density of 5×105 cells mL−1 was attained after 96 h. Based on these growth curves and to ensure optimal nutritive quality of the algae, cultures used for feeding were discarded after a maximum of 168 h for Isochrysis and C. calcitrans (≈5–6×106 cells mL−1), and 264 h for R. reticulata (≈2×106 cells mL−1).


Culture optimization for the emergent zooplanktonic model organism Oikopleura dioica.

Bouquet JM, Spriet E, Troedsson C, Otterå H, Chourrout D, Thompson EM - J. Plankton Res. (2009)

Growth curves at 20°C under continuous illumination for algae used as food sources. Cell concentrations (C, cells mL−1) at times (T, days), were calculated from optical densities using the species specific equations defined in Fig. 2. Growth rates were determined using the equation K = (lnC2−lnC1)/(T2−T1): where K is the growth rate (days−1) and lnCx are the natural logarithms of cell concentrations at the time points Tx. The intersection points (arrows) of the broken lines with the growth curves indicate the lower (T1) and upper (T2) limits of the linear growth phases of the algal cultures that were used for feeding. Doubling times (T2, days) were calculated as T2 = ln2/K. Vertical bars indicate standard errors (N = 6).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2651036&req=5

FBN132F3: Growth curves at 20°C under continuous illumination for algae used as food sources. Cell concentrations (C, cells mL−1) at times (T, days), were calculated from optical densities using the species specific equations defined in Fig. 2. Growth rates were determined using the equation K = (lnC2−lnC1)/(T2−T1): where K is the growth rate (days−1) and lnCx are the natural logarithms of cell concentrations at the time points Tx. The intersection points (arrows) of the broken lines with the growth curves indicate the lower (T1) and upper (T2) limits of the linear growth phases of the algal cultures that were used for feeding. Doubling times (T2, days) were calculated as T2 = ln2/K. Vertical bars indicate standard errors (N = 6).
Mentions: To examine growth rates of the algal strains, cultures were inoculated with an initial cell density of 2.5×104 cells mL−1. Sampling for optical density measurement was carried out twice on the first day and then once per day thereafter (Fig. 3). Growth rates (K) and doubling times (T2) during the linear portion of the exponential growth curves were calculated as indicated in the figure legend. Cell densities of Isochrysis sp. and C. calcitrans increased rapidly with a minor lag phase, whereas R. reticulata grew less rapidly. For routine use in the feeding of O. dioica, minimum cell densities of 1×106 cells mL−1 were reached after 48 h for Isochrysis and 72 h for C. calcitrans. For R. reticulata, a minimum density of 5×105 cells mL−1 was attained after 96 h. Based on these growth curves and to ensure optimal nutritive quality of the algae, cultures used for feeding were discarded after a maximum of 168 h for Isochrysis and C. calcitrans (≈5–6×106 cells mL−1), and 264 h for R. reticulata (≈2×106 cells mL−1).

Bottom Line: This urochordate, has a simplified anatomical organization, remains transparent throughout an exceptionally short life cycle of less than 1 week and exhibits high fecundity.At 70 Mb, the compact, sequenced genome ranks among the smallest known metazoan genomes, with both gene regulatory and intronic regions highly reduced in size.The organism occupies an important trophic role in marine ecosystems and is a significant contributor to global vertical carbon flux.

View Article: PubMed Central - PubMed

Affiliation: Sars International Centre for Marine Molecular Biology, Thormøhlensgate 55, N-5008 Bergen , Norway.

ABSTRACT
The pan-global marine appendicularian, Oikopleura dioica, shows considerable promise as a candidate model organism for cross-disciplinary research ranging from chordate genetics and evolution to molecular ecology research. This urochordate, has a simplified anatomical organization, remains transparent throughout an exceptionally short life cycle of less than 1 week and exhibits high fecundity. At 70 Mb, the compact, sequenced genome ranks among the smallest known metazoan genomes, with both gene regulatory and intronic regions highly reduced in size. The organism occupies an important trophic role in marine ecosystems and is a significant contributor to global vertical carbon flux. Among the short list of bona fide biological model organisms, all share the property that they are amenable to long-term maintenance in laboratory cultures. Here, we tested diet regimes, spawn densities and dilutions and seawater treatment, leading to optimization of a detailed culture protocol that permits sustainable long-term maintenance of O. dioica, allowing continuous, uninterrupted production of source material for experimentation. The culture protocol can be quickly adapted in both coastal and inland laboratories and should promote rapid development of the many original research perspectives the animal offers.

No MeSH data available.