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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Allelopathy (filtrate cross-culturing) |- | '''Approach:''' cell-free filtrate of candidate allelopathic species added to target species culture; growth or motility response measured |- | '''Contex..."

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Created page with "{{BreadcrumbsInteractions}} * Page authors: PRIMO * Responsible curator: Hagen Buck-Wiese ---- __TOC__ <div class="model-box"> {| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Allelopathy (filtrate cross-culturing) |- | '''Approach:''' cell-free filtrate of candidate allelopathic species added to target species culture; growth or motility response measured |- | '''Contex..."

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* [[Page authors|Page authors]]: [[PRIMO]]
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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;"
! Allelopathy (filtrate cross-culturing)
|-
| '''Approach:''' cell-free filtrate of candidate allelopathic species added to target species culture; growth or motility response measured
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| '''Context:''' lab
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| '''Spatial scale:''' culture flask (point)
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| '''Temporal scale:''' hours to days
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| '''Units:''' cells L<sup>-1</sup> d<sup>-1</sup>; Fv/Fm; settling rate
|-
| '''Community captured:''' individual target species
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| '''Co-measurements:''' temperature, PAR; sometimes pH and salinity
|}
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== Method Overview ==

The filtrate cross-culturing approach tests for allelopathic effects — inhibitory compounds produced and released by one organism affecting the physiology or behavior of another. Cell-free filtrate (0.2 µm or 0.45 µm filtered) from a potentially allelopathic species (the donor) is added to cultures of a target (recipient) species. The donor filtrate is assumed to contain any secreted allelopathic compounds without cells; controls receive equal volumes of filtered seawater. Target species growth rate, photosynthetic efficiency (Fv/Fm from variable fluorescence), or motility (settling rate in motile flagellates) are monitored over hours to days. Inhibition of growth or photosynthesis relative to the seawater control indicates allelopathic activity<ref name="Kearns2001">Kearns, K. D., & Hunter, M. D. (2001). Toxin-producing Anabaena flos-aquae induces settling of Chlamydomonas reinhardtii, a competing motile alga. ''Microbial Ecology'', 42(1), 80–86. https://doi.org/10.1007/s002480000086</ref>.

=== Scale of measurement ===

Laboratory culture; no direct ''in situ'' spatial scale. Incubations of hours to days.

=== Data generated ===

Growth rate, Fv/Fm, or settling rate of the target species in the presence vs. absence of the filtrate. A significant inhibition indicates allelopathic potential of the donor species.

=== Units & currency ===

Units are cells L<sup>-1</sup> d<sup>-1</sup> (growth) or Fv/Fm (photosynthesis). The currency is phytoplankton/cyanobacteria cell abundance or motility behavior.

=== Sample size ===

Typical samples are < 1 L in volume per treatment.

=== Repositories & databases ===

== Limitations ==

The method assumes that no competition for resources (nutrients, light) occurs between donor compounds and target growth; in practice, carrier media differences can confound results. The concentration of allelopathic compound in the filtrate may differ substantially from ''in situ'' conditions, leading to overestimation if natural donor densities are lower than in culture. Bottle effects may arise.

== Example Applications & Protocols ==

=== Classic examples ===
* Kearns & Hunter (2001) ''Toxin-producing Anabaena flos-aquae induces settling of Chlamydomonas reinhardtii, a competing motile alga'' <ref name="Kearns2001" />
* Arzul et al. (1999) ''Comparison of allelopathic properties in three toxic Alexandrium species'' <ref name="Arzul1999">Arzul, G., Seguel, M., Guzman, L., & Erard-Le Denn, E. (1999). Comparison of allelopathic properties in three toxic Alexandrium species. ''Journal of Experimental Marine Biology and Ecology'', 232(2), 285–295. https://doi.org/10.1016/S0022-0981(98)00120-8</ref>

=== Recent applications ===
*

=== Common calculations/conversions ===
* % inhibition = (µ<sub>control</sub> − µ<sub>filtrate</sub>) / µ<sub>control</sub> × 100; positive values indicate allelopathic growth inhibition.

== References ==

[[Category:Main Pages|Model types]]

Filtrate cross-culturing - Revision history