scholarly journals One in a Million: Genetic Diversity and Conservation of the Reference Crassostrea angulata Population in Europe from the Sado Estuary (Portugal)

Life ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1173
Author(s):  
Stefania Chiesa ◽  
Livia Lucentini ◽  
Paula Chainho ◽  
Federico Plazzi ◽  
Maria Manuel Angélico ◽  
...  

The production of cupped oysters is an important component of European aquaculture. Most of the production relies on the cultivation of the Pacific oyster Crassostrea gigas, although the Portuguese oyster Crassostrea angulata represents a valuable product with both cultural and economic relevance, especially in Portugal. The authors of the present study investigated the genetic diversity of Portuguese oyster populations of the Sado estuary, both from natural oyster beds and aquaculture facilities, through cox1 gene fragment sequencing. Then, a comparison with a wide dataset of cupped oyster sequences obtained from GenBank (up to now the widest available dataset in literature for the Portuguese oyster) was performed. Genetic data obtained from this work confirmed that the Pacific oyster does not occur in the natural oyster beds of the Sado estuary but showed that the species occasionally occurs in the oyster hatcheries. Moreover, the results showed that despite the founder effect and the bottleneck events that the Sado populations have experienced, they still exhibit high haplotype diversity. Risks are arising for the conservation of the Portuguese oyster reference populations of the Sado estuary due to the occurrence of the Pacific oyster in the local hatcheries. Therefore, researchers, local authorities, and oyster producers should work together to avoid the loss of this valuable resource.

Genetics ◽  
2021 ◽  
Author(s):  
Xiaoshen Yin ◽  
Dennis Hedgecock

Abstract Understanding the genetic bases of inbreeding depression, heterosis, and genetic load is integral to understanding how genetic diversity is maintained in natural populations. The Pacific oyster Crassostrea gigas, like many long-lived plants, has high fecundity and high early mortality (type-III survivorship), manifesting a large, overt, genetic load; the oyster harbors an even greater concealed genetic load revealed by inbreeding. Here, we map viability QTL (vQTL) in six interrelated F2 oyster families, using high-density linkage maps of single nucleotide polymorphisms generated by genotyping-by-sequencing (GBS) methods. Altogether, we detect 70 vQTL and provisionally infer 89 causal mutations, 11 to 20 per family. Genetic mortality caused by independent (unlinked) vQTL ranges from 94.2% to 97.8% across families, consistent with previous reports. High-density maps provide better resolution of genetic mechanisms, however. Models of one causal mutation present in both identical-by-descent (IBD) homozygotes and heterozygotes fit genotype frequencies at 37 vQTL; consistent with the mutation-selection balance theory of genetic load, 20 are highly deleterious, completely recessive mutations and 17 are less deleterious, partially dominant mutations. Another 22 vQTL require pairs of recessive or partially dominant causal mutations, half showing selection against recessive mutations linked in repulsion, producing pseudo-overdominance. Only eight vQTL appear to support the overdominance theory of genetic load, with deficiencies of both IBD homozygotes, but at least four of these are likely caused by pseudo-overdominance. Evidence for epistasis is absent. A high mutation rate, random genetic drift, and pseudo-overdominance may explain both the oyster’s extremely high genetic diversity and a high genetic load maintained primarily by mutation-selection balance.


2017 ◽  
Vol 92 (6) ◽  
pp. 696-702 ◽  
Author(s):  
R. Jafari ◽  
B. Sanei ◽  
A. Baradaran ◽  
A. Spotin ◽  
B. Bagherpour ◽  
...  

AbstractCystic echinococcosis (CE) is a medically important parasite-caused human disease. Humans may acquire the infection accidentally by ingestion of E. granulosus eggs. The parasite has a broad range of hosts and genotypes, which may affect its aetiological and biological characteristics. The present study aimed to determine the genetic characteristics of human isolates of E. granulosus in Isfahan, Iran. In this cross-sectional study, 50 surgically removed hydatid cysts were collected from hospitalized patients in Al-Zahra Hospital, Isfahan, Iran, over a period of 2 years (2015–2017). DNA was extracted from cyst material, and polymerase chain reactions (PCR) were performed targeting cox1 and nad1 genes. Amplicons were sequenced directly and the resulting sequences were aligned and analysed. Phylogenetic and genetic diversity analyses were also performed. Among the isolates, 43 (86%), 3 (6%) and 4 (8%) out of 50 were E. granulosus (G1), E. granulosus (G3) and E. intermedius (G6), respectively. In total, nine and eight haplotypes were identified by nad1 and cox1 gene analysis, respectively. The haplotype diversity index was higher by cox1 gene analysis (0.547) in G1 strains compared with nad1 (0.433). The G1 genotype was the most predominant isolate from human cases of CE, and the presence of G6 is indicative of an important role of camels in the development of human CE in Isfahan. This is the first report of the G3 genotype causing human CE in Isfahan. Moreover, cox1 gene analysis enables a higher resolution of the genetic diversity of the E. granulosus population compared with nad1 gene analysis.


Author(s):  
Abolghasem SIYADATPANAH ◽  
Ahmad DARYANI ◽  
Shahabeddin SARVI ◽  
Adel SPOTIN ◽  
Mehdi SHARIF ◽  
...  

Background: Human Echinococcosisis a cyclo-zoonotic infection caused by tapeworms of the Echinococcus granulosus sensu stricto complex. The detection of mitochondrial genome data of genus Echinococcus can reflect the taxonomic status, genetic diversity, and population structure genetics. Methods: Totally, 52 formalin-fixed paraffin-embedded (FFPE) tissue samples from patients with histologically confirmed CE were collected from Mazandaran province, Iran in the period of Mar 1995 to May 2018. All extracted DNAs from (FFPE) tissue samples were subjected to amplify by polymerase chain reactions method targeting cytochrome c oxidase subunit 1 (cox1) gene. All PCR amplicons were sequenced to phylogenetic analysis and genetic diversity. Results: Molecular analysis showed that 50(96.1%) and 2 (3.84%) isolates were identified as G1 andG3 E. granulosus genotypes, respectively. DNA sequence analyses indicated a high gene diversity for G1 (Haplotype diversity: 0.830) and G3 genotypes (Hd: 1.00). Based on multiple sequence alignment analyses, 7 (13.46%; G1 genotype) and 2 (3.84%; G3 genotype) new haplotypes were unequivocally identified. Conclusion: G3 genotype (Buffalo strain) was identified from two human hydatidosis isolates in the region. Present study strengthens our knowledge about taxonomic status, transmission patterns of Echinococcus parasite to human and heterogeneity aspects of this parasite in clinical CE isolates of Northern Iran.


2002 ◽  
Vol 11 (8) ◽  
pp. 1499-1514 ◽  
Author(s):  
Pauline Helene Garnier-Gere ◽  
Yamama Naciri-Graven ◽  
Serge Bougrier ◽  
Antonios Magoulas ◽  
Maurice Heral ◽  
...  

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