麻豆淫院

Hong Kong Polytechnic University scientists report that multigenerational exposure to microplastic-contaminated prey reverses natural food preferences in nematodes, revealing a learned attraction to contaminated prey.

Animals must evaluate food based on taste, odor, and texture to avoid harmful intake. When possible, they adjust preferences based on experience and associate flavors with outcomes.

Pollutants now pervade food sources in many ecosystems, leading to widespread ingestion across wildlife populations. Microplastics, because of their small size, are frequently consumed by mistake and small organisms may confuse them with bacteria or fungi, especially in polluted environments.

In the study, "Microplastics Alter Predator Preferences of Prey through Associative Learning," in Environmental Science & Technology Letters, researchers designed behavioral assays to test whether predatory nematodes could detect and discriminate between microplastic-contaminated and uncontaminated prey, and whether that discrimination could be modified by experience.

In experimental settings using Caenorhabditis elegans, researchers observed that worms raised on bacterial diets migrated toward uncontaminated (microplastic free) food patches when given a choice.

When fed bacteria mixed with polystyrene microplastics over successive generations, the worms developed an attraction to the microplastic-contaminated food. These behavioral shifts require functional olfactory learning, implicating the lrn-1 gene.

In both agar-based and soil microcosm platforms, nematode foraging behavior followed exposure history rather than innate preference. Trained predators selected prey resembling their previous environments, altering the direction of prey pursuit in response to generational contamination exposure.

Odr-10 mutants, which lack a functional olfactory chemosensory receptor, showed no preference between clean and dirty food, indicating the ability to detect microplastic contamination exists and requires odr-10-mediated olfactory input.

Worms conditioned to contaminated food across three sequential generations developed a preference for it. lrn-1 mutants, which are deficient in olfactory associative learning, did not acquire this behavioral shift even after multigenerational exposure to contaminated prey, indicating that altered foraging behavior required functional learning machinery.

Authors conclude that microplastic exposure changed predator foraging behavior by altering how normal prey was perceived. Initially, the contamination modified the olfactory profile of bacterial prey to make it seem less appealing, prompting avoidance. Once accustomed to only surviving on the contaminated profile, a new preference took over.

The researchers expressed concern that generational conditioning to contaminated prey may disrupt trophic cascades and nutrient flow in polluted ecosystems. Microplastic-trained predators could restructure food webs by shifting prey distribution and abundance.

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