Eierman Laura E, Landis Jacob
Biological Sciences Department, SUNY Cortland, Cortland, New York, United States of America.
School of Integrative Plant Science, Section of Plant Biology and the L.H. Bailey Hortorium, Cornell University, Ithaca, New York, United States of America.
PLoS One. 2025 Apr 29;20(4):e0319165. doi: 10.1371/journal.pone.0319165. eCollection 2025.
The degradation of marine plastic debris poses a threat to organisms by fragmenting into micro- and nano-scale pieces and releasing a complex chemical leachate into the water. Numerous studies have investigated harms from plastic pollution such as microplastic ingestion and exposure to single chemicals. However, few studies have examined the holistic threat of plastic exposure and the synergistic impacts of chemical mixtures. The objective of this study was to measure changes in gene expression of gill and gonadal tissue of the eastern oyster (Crassostrea virginica) in response to plastic debris exposure during their first year, using RNA-seq to explore multiple types of physiological responses. Shell and polyethylene terephthalate plastic were used as substrate for the metamorphosis of larval oysters in a settlement tank. Substrate pieces were then transferred to metal cages and outplanted in pairs - shell cage and plastic cage - onto restoration reefs in the St. Mary's River, Maryland, USA. After 10 months of growth, the oysters were collected, gill and gonadal tissue removed, and sex identified. The tissues of six oysters from each sex and substrate type were then analyzed in RNA-seq. Both gill and gonadal tissue samples had altered expression of immune and stress-response genes in response to plastic exposure. Genes upregulated in response to plastic were enriched for gene ontology functions of proteolysis and fibrinolysis. Downregulated genes were involved in shell biomineralization and growth. One male oyster exposed to plastic had "feminized" gene expression patterns despite developing mature sperm, suggesting plastic leachate can alter gene expression and shift protandric individuals to develop as females. Plastic pollution may therefore reduce shell growth, initiate immune and stress responses, alter sex differentiation, and impact reproductive output of eastern oysters through changes in transcription.
海洋塑料碎片的降解对生物构成了威胁，因为它们会破碎成微米和纳米级的碎片，并向水中释放复杂的化学渗滤液。许多研究调查了塑料污染的危害，如微塑料摄入和单一化学物质的暴露。然而，很少有研究考察塑料暴露的整体威胁以及化学混合物的协同影响。本研究的目的是测量东部牡蛎（弗吉尼亚巨蛎）鳃和性腺组织在第一年接触塑料碎片时基因表达的变化，使用RNA测序来探索多种类型的生理反应。贝壳和聚对苯二甲酸乙二酯塑料被用作育苗池中幼体牡蛎变态的基质。然后将基质碎片转移到金属笼中，并成对（贝壳笼和塑料笼）移植到美国马里兰州圣玛丽河的修复礁上。生长10个月后，收集牡蛎，取出鳃和性腺组织，并鉴定性别。然后对来自每种性别和基质类型的六只牡蛎的组织进行RNA测序分析。鳃和性腺组织样本在接触塑料后，免疫和应激反应基因的表达均发生了改变。对塑料产生反应而上调的基因在蛋白水解和纤维蛋白溶解的基因本体功能中富集。下调的基因参与贝壳生物矿化和生长。一只接触塑料的雄性牡蛎尽管发育出了成熟的精子，但却具有“雌性化”的基因表达模式，这表明塑料渗滤液可以改变基因表达，并使雄性先熟个体发育为雌性。因此，塑料污染可能会通过转录变化减少东部牡蛎的贝壳生长、引发免疫和应激反应、改变性别分化并影响生殖产出。
