An alpha-2 macroglobulin in the pearl oyster Pinctada fucata: Characterization and function in hemocyte phagocytosis of Vibrio alginolyticus

Abstract In the summers of 2019 and 2020, a previously undescribed disease occurred in both juvenile and adult shellfish, causing mass mortalities in cultured pearl production, characterized by the major symptom of extreme atrophy of the soft tissues, including the mantle. However, the causative organism was uncertain. We isolated Vibrio sp. strain MA3 from the mantles of diseased pearl oysters Pinctada fucata. Analyses of 16S rRNA gene and DNA gyrase sequence homologies and its biochemical and morphological characteristics suggested that strain MA3 is a new strain of Vibrio alginolyticus. In addition, a hemolysin gene (Vhe1) of strain MA3 was detected as one of the virulence factors, and the complete sequence was determined. BLAST searches showed that Vhe1 shares 99.8% nucleotide sequence identity with Vibrio alginolyticus strain A056 lecithin-dependent hemolysin (ldh) gene, complete cds. Experimental infection of healthy oysters via injection with strain MA3 indicated it could cause high mortalities of the typically affected oysters from which the strain was isolated. These results suggest that the newly isolated Vibrio sp. strain MA3 is a putative causal agent of the recent disease outbreaks in Akoya pearl oysters.

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Identification and Characterization of microRNAs and Their Predicted Functions in Biomineralization in the Pearl Oyster (Pinctada fucata)

Biology ◽

10.3390/biology8020047 ◽

2019 ◽

Vol 8 (2) ◽

pp. 47 ◽

Cited By ~ 4

Author(s):

Songqian Huang ◽

Yuki Ichikawa ◽

Kazutoshi Yoshitake ◽

Shigeharu Kinoshita ◽

Yoji Igarashi ◽

...

Keyword(s):

Expression Patterns ◽

Target Prediction ◽

Adductor Muscle ◽

Pearl Oyster ◽

Pinctada Fucata ◽

Internal Reference ◽

Stem Loop ◽

Ongoing Research ◽

U6 Snrna ◽

And Function

The biological process of pearl formation is an ongoing research topic, and a number of genes associated with this process have been identified. However, the involvement of microRNAs (miRNAs) in biomineralization in the pearl oyster, Pinctada fucata, is not well understood. In order to investigate the divergence and function of miRNAs in P. fucata, we performed a transcriptome analysis of small RNA libraries prepared from adductor muscle, gill, ovary, and mantle tissues. We identified 186 known and 42 novel miRNAs in these tissues. Clustering analysis showed that the expression patterns of miRNAs were similar among the somatic tissues, but they differed significantly between the somatic and ovary tissues. To validate the existence of the identified miRNAs, nine known and three novel miRNAs were verified by stem-loop qRT-PCR using U6 snRNA as an internal reference. The expression abundance and target prediction between miRNAs and biomineralization-related genes indicated that miR-1990c-3p, miR-876, miR-9a-3p, and novel-3 may be key factors in the regulatory network that act by controlling the formation of matrix proteins or the differentiation of mineralogenic cells during shell formation in mantle tissue. Our findings serve to further clarify the processes underlying biomineralization in P. fucata.

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