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We evaluated the potential of metabarcoding in assessing the environmental DNA (eDNA) biodiversity profile in the water column of an hydroelectric power plant reservoir in southeast Brazil. Samples were obtained in three technical replicates at 1 km from the dam at 1, 13 and 25 m depths. For each minibarcodes -- COI, 12S and 16S -- 1.5 million paired-reads (150 base pairs) were sequenced. A total of 44 unique taxa were found. COI identified most of the taxa (34 taxa; 77.2 %) followed by 16S (14; 31.8 %) and 12S (10; 22.7 %). All minibarcodes identified fishes (13 taxa), however, COI detected other aquatic macro-invertebrates (18), algae (3) and amoebas (2). Richness was the same across the three depths (35 taxa), although, beta diversity suggested slightly divergent profiles. In just one location we identified 15 taxa never reported previously, 50% of the fish species identified in the last year of fishery monitoring and 13% of the species in biodiversity surveys performed from 2012 to 2021. Clustering into Amplicon Sequence Variants (ASV) showed that 12S and 16S are able to detect predominant haplotypes of fishes, suggesting they are suitable to study population genetics of this group. In this study we reviewed the species occurring within the Três Irmãos reservoir according to previous conventional surveys and demonstrated that eDNA metabarcoding can be applied to monitor its biodiversity.

The golden mussel (Limnoperna fortunei) is a freshwater bivalve that was introduced in South America almost 30 years ago, likely through ballast water of Asian ships. Since then, it has spread across the continent, causing both economic and environmental impacts. The study of the population structure of an invasive species may bring valuable insights towards understanding its pattern of dispersion, which in turn will help to create more effective management plans. Here, we have compared mussel populations from 5 different Brazilian reservoirs and tested for the presence of geographic genetic structure. In order to obtain a high number of single nucleotide variants (SNVs) at good cost-benefit, we have for the first time applied the double digest restriction-site associated DNA sequencing (ddRAD-seq) protocol for the golden mussel. The ddRAD-seq protocol allowed us to obtain 2046 SNVs, which were then used to assess population structure by applying three independent methodologies: Principal Component Analysis (PCA), Bayesian Clustering and Phylogenetic Tree. All methodologies have indicated absent geographic structure.

The golden mussel (Limnoperna fortunei) is an Asian invasive bivalve that threats aquatic biodiversity and causes economic damage, especially to the hydroelectric sector in South America. Traditional control methods have been inefficient to stop the advance of the invasive mollusk, which currently is found in 40% of Brazilian hydroelectric power plants. In order to develop an effective strategy to stop golden mussel infestations, we need to better understand its reproductive and sexual mechanisms. In this study, we sequenced total RNA samples from male and female golden mussel gonads in the spawning stage. A transcriptome was assembled resulting in 200,185 contigs with 2,250 bp N50 and 99.3% completeness. Differential expression analysis identified 3,906 differentially expressed transcripts between the sexes. We searched for genes related to the sex determination/differentiation pathways in bivalves and model species and investigated their expression profiles in the transcriptome of the golden mussel gonads. From a total of 187 genes identified in the literature, 131 potential homologs were found in the L. fortunei transcriptome, of which 15 were overexpressed in males and four in females. To this group belong gene families relevant to sexual development in various organisms, from mammals to invertebrates, such as Dmrt (doublesex and mab3-related-transcription factor), Sox (SRY-related HMG-box) and Fox (forkhead box). Our work contributes to a broader understanding of sex differentiation in golden mussel and reveals candidate target genes for the development of biotechnological strategies to control its reproduction in order to stop L. fortunei infestations.

Background. Insufficient quantities of freshly harvested Limnoperna fortunei gametes and embryos constrain reproduction research in the laboratory. Cryopreservation would allow the accumulation and storage of gametes when they are available. The lack of available cryopreservation protocol for Limnoperna fortunei in the literature led our research group to undertake a study to establish which cryoprotective agents can be might be most useful for cryopreservation of this species’ sperm. Methods. 2%, 5%, and 10% concentration of ethylene glycol, dimethyl sulfoxide, glycerol, and polyethylene glycol 4000 as well as 0.2 M glucose, sucrose, and trehalose (mixed into the 10% concentration of the aforementioned agents) were tested in a 1:1 ratio with sperm, in 0.25 ml straws, frozen in liquid nitrogen. Results. After 48 hours the best survival rate was in the samples with 10% polyethylene glycol 4000, 36.1%, which also resulted in viable sperm after 7 and 15 days.

To investigate the biocatalytic potential of Colletotrichum acutatum and Colletotrichum nymphaeae for monoterpene biotransformation. C. acutatum and C. nymphaeae used limonene, α-pinene, β-pinene, farnesene, citronellol, linalool, geraniol, perillyl alcohol, and carveol as sole carbon and energy sources. Both species biotransformed limonene and linalool, accumulating limonene-1,2-diol and linalool oxides, respectively. α-Pinene was only biotransformed by C. nymphaeae producing campholenic aldehyde, pinanone and verbenone. The biotransformation of limonene by C. nymphaeae yielded 3.34–4.01 g limonene-1,2-diol l−1, depending on the substrate (R-(+)-limonene, S-(−)-limonene or citrus terpene (an agro-industrial by-product). This is among the highest concentrations already reported for this product. This is the first report on the biotransformation of these terpenes by Colletotrichum spp. and the biotransformation of limonene to limonene-1,2-diol possibly involves enzymes similar to those found in Grosmannia clavigera.

Biological invasions currently pose major threats to ecosystems worldwide. Invasive bivalves such as the Golden Mussel Limnoperna fortunei can act as ‘environmental engineers’, altering biogeochemistry, reducing biodiversity, and literally changing the landscape of aquatic environments. The risk that this mussel will invade the Amazon basin is a great concern for environmental authorities, especially because no efficient control methods presently exist. In this study, we tested new microencapsulated chemicals, along with the traditional dissolved chlorine and KCl, as alternatives to control L. fortunei infestation in industrial and water supply plants along rivers. Because these bivalves can close their valves when they sense toxic substances in the water, microencapsulation has improved the effectiveness of the chemicals in controlling L. fortunei, reducing variation in the application and increasing toxicity compared to dissolved chemicals. Microencapsulation should be seriously considered as an alternative to replace hazardous chlorine.

Here we describe the mitochondrial genome of the golden mussel Limnoperna fortunei, an Asian bivalve which has become one of the most aggressive invasive species in Japan and South America. The mitochondrial genome of L. fortunei does not present conserved gene arrangement when compared to the other Mytilidae species suggesting a high degree of gene recombination in the mitochondria of this clade. In addition, the golden mussel mitogenome encodes two copies of tRNA(Lys) and presents a putative pseudogene for the atp8 gene sequence that encodes a 27 amino acid peptide containing an in-frame stop codon. The presence of this pseudogene raises the question as to whether atp8 is encoded in some bivalve mitochondrial genomes or not. The phylogenetic analysis of all complete mitochondrial genomes available from Mytilidae mussels confirmed the close evolutionary relationships among bivalves from the genus Mytilys and placed L. fortunei coming from a more ancestral branch on the family. The supermatrix phylogeny described used the concatenation of all 12 genes from the mitochondria and disputed the monophyly of the genus Perna, as Perna perna was shown to be more closely related to Brachidontes exustus than to Perna viridis. The comparative analysis of mitogenome synteny also confirmed the polyphyly of the genus Perna. The complete and annotated mitogenome has been published in GenBank under the accession number KP756905.

Successful invasive species often share some ecological traits, such as rapid growth and rapid sexual maturation, both of which are characteristic of Limnoperna fortunei. In addition, phenotypic plasticity, i.e., the capability to express different phenotypes as a response to diverse environmental challenges, may play a fundamental role in the geographic expansion of many invasive species, including the golden mussel. Little is known about the genetics of L. fortunei, but the first transcriptome for L. fortunei has recently been sequenced and gene–environment relationships that are likely associated with the successful invasions of this species have begun to be elucidated. Over 24,000 transcripts have been functionally annotated, and results suggest the expansion of the gene families’ heat shock protein 70 and cytochrome P450. This may indicate that L. fortunei has a broad genetic repertoire that confers it an advantage to deal with stressors presented in new locations. Several other key genes such as byssus proteins, immune system-related genes, and antioxidant enzymes have been characterized and are now available for gene expression studies. A genome project is being carried out in Brazil to characterize the entire set of genes and gene families of L. fortunei. This will expand our current knowledge of the genetic characteristics of the invasion helping to forecast new invasion events and develop biotechnology-based strategies to control the infestation.

The success of the Asian bivalve Limnoperna fortunei as an invader in South America is related to its high acclimation capability. It can inhabit waters with a wide range of temperatures and salinity and handle long-term periods of air exposure. We describe the transcriptome of L. fortunei aiming to give a first insight into the phenotypic plasticity that allows non-native taxa to become established and widespread. We sequenced 95,219 reads from five main tissues of the mussel L. fortunei using Roche’s 454 and assembled them to form a set of 84,063 unigenes (contigs and singletons) representing partial or complete gene sequences. We annotated 24,816 unigenes using a BLAST sequence similarity search against a NCBI nr database. Unigenes were divided into 20 eggNOG functional categories and 292 KEGG metabolic pathways. From the total unigenes, 1,351 represented putative full-length genes of which 73.2% were functionally annotated. We described the first partial and complete gene sequences in order to start understanding bivalve invasiveness. An expansion of the hsp70 gene family, seen also in other bivalves, is present in L. fortunei and could be involved in its adaptation to extreme environments, e.g. during intertidal periods. The presence of toll-like receptors gives a first insight into an immune system that could be more complex than previously assumed and may be involved in the prevention of disease and extinction when population densities are high. Finally, the apparent lack of special adaptations to extremely low O2 levels is a target worth pursuing for the development of a molecular control approach.

We report the construction and characterization of a normalized cDNA library from the digestive gland of the marine bivalve Nodipecten nodosus , a commercially valuable tropical scallop. A total of 288 clones were sequenced, and 250 unique sequences were obtained. The cDNA library showed a small sequence redundancy (2.3%) and high numbers of recombinant (99.9%) and independent clones (2.0 × 10 6 cfu), indicating that the cDNA library generated in this study is a profitable resource for efficient gene discovery for N. nodosus . EST functional annotation by Gene Ontology term assignment revealed the identification of sequences potentially involved in aquaculture and ecotoxicology relevant processes such as apoptosis, growth, lipid metabolism, reproduction, development, response to stress and immunity.

The complete sequence of the brown mussel Perna perna mitochondrial genome is described in this article. It was sequenced in 1/11 of an Illumina HiSeq lane using Nextera multiplexing kit. The mitogenome was assembled using both (i) de novo assembly and (ii) referenced-based strategies with mitoMaker software. Perna perna mitogenome is a circular molecule of 18,415 bp in size, containing 12 protein-coding genes, 23 transfer RNAs, 2 ribossomal RNAs and several non-coding regions. As shown in the previous studies, Perna perna does not present the doubly uniparental inheritance system (DUI) of mitochondria and does not encode the ATPase8 gene, in accordance with other Mytilidae data.