Characterization of the mitochondrial genomes of the Mexican endemic bats Corynorhinus mexicanus and Corynorhinus leonpaniaguae (Chiroptera: Vespertilionidae).

BACKGROUND: The genus Corynorhinus is composed of four recognized species: C. rafinesquii, C. townsendii, C. mexicanus, and C. leonpaniaguae, the latter two being endemic to Mexico. According to the IUCN, C. mexicanus is considered "Near Threatened", as its populations are dwindling and habitats are affected by anthropogenic disturbance. Corynorhinus leonpaniaguae has not been assigned to an IUCN Red List risk category due to its recent description. METHODS AND RESULTS: In this study, the mitochondrial genomes of C. mexicanus and C. leonpaniaguae were assembled and characterized in detail. The mitochondrial genomes (mtDNA) of C. mexicanus and C. leonpaniaguae have lengths of 16,470 and 16,581 bp respectively, with a predominant nucleotide usage of adenine (31.670% and 31.729%, respectively) and thymine (26.15% and 26.18%, respectively). The mtDNA of C. mexicanus and C. leonpaniaguae is composed of 37 coding and non-coding elements: 22 transfer RNAs (tRNA), 13 protein-coding genes (PCGs), two ribosomal RNAs and a non-coding region, the control region, which has a length of 933 bp and 1,149 bp, respectively. All tRNAs exhibited a cloverleaf secondary structure, with the exception of trn-Ser1 which showed a deletion of the dihydrouridine arm in the two species. All PCGs are subjected to purifying selection, with atp8 being the gene showing the highest Ka/Ks value. CONCLUSIONS: These are the first whole mitogenomic resources developed for C. mexicanus and C. leonpaniaguae and enhance our knowledge of the ecology of these species and aid in their conservation.

Characterization of the complete mitochondrial genome of the brazilian cownose ray Rhinoptera brasiliensis (Myliobatiformes, Rhinopteridae) in the western Atlantic and its phylogenetic implications.

BACKGROUND: The Brazilian cownose ray, Rhinoptera brasiliensis has undergone a global population reduction and is currently classified by IUCN as Vulnerable. This species is sometimes confused with Rhinoptera bonasus, the only external diagnostic characteristic to distinguish between both species is the number of rows of tooth plates. Both cownose rays overlap geographically from Rio de Janeiro to the western North Atlantic. This calls for a more comprehensive phylogenetic assessment using mitochondria DNA genomes to better understand the relationships and delimitation of these two species. METHODS AND RESULTS: The mitochondrial genome sequences of R. brasiliensis was obtained by next-generation sequencing. The length of the mitochondrial genome was 17,759 bp containing 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a non-coding control region (D-loop). Each PCG was initiated by an authoritative ATG codon, except for COX1 initiated by a GTG codon. Most of the PCGs were terminated by a complete codon (TAA/TAG), while an incomplete termination codon (TA/T) was found in five out of the 13 PCGs. The phylogenetic analysis showed that R. brasiliensis was closely related to R. steindachneri whereas the reported mitogenome as R. steindachneri (GenBank accession number KM364982), differs from multiple mitocondrial DNA sequences of R. steindachneri and is nearly identical to that of R. javanica. CONCLUSION: The new mitogenome determined in this study provides new insight into the phylogenetic relationships in Rhinoptera, while providing new molecular data that can be applied to population genetic studies.

The Genome of the Marine Alga Ulva compressa (Chlorophyta) Reveals Protein-Coding Genes with Similarity to Plants and Green Microalgae, but Also to Animal, Bacterial, and Fungal Genes.

The genome of the marine alga Ulva compressa was assembled using long and short reads. The genome assembly was 80.8 Mb in size and encoded 19,207 protein-coding genes. Several genes encoding antioxidant enzymes and a few genes encoding enzymes that synthesize ascorbate and glutathione were identified, showing similarity to plant and bacterial enzymes. Additionally, several genes encoding signal transduction protein kinases, such as MAPKs, CDPKS, CBLPKs, and CaMKs, were also detected, showing similarity to plants, green microalgae, and bacterial proteins. Regulatory transcription factors, such as ethylene- and ABA-responsive factors, MYB, WRKY, and HSTF, were also present and showed similarity to plant and green microalgae transcription factors. Genes encoding enzymes that synthesize ACC and ABA-aldehyde were also identified, but oxidases that synthesize ethylene and ABA, as well as enzymes that synthesize other plant hormones, were absent. Interestingly, genes involved in plant cell wall synthesis and proteins related to animal extracellular matrix were also detected. Genes encoding cyclins and CDKs were also found, and CDKs showed similarity to animal and fungal CDKs. Few genes encoding voltage-dependent calcium channels and ionotropic glutamate receptors were identified as showing similarity to animal channels. Genes encoding Transient Receptor Potential (TRP) channels were not identified, even though TRPs have been experimentally detected, indicating that the genome is not yet complete. Thus, protein-coding genes present in the genome of U. compressa showed similarity to plant and green microalgae, but also to animal, bacterial, and fungal genes.

Comparative Genomics in Drosophila.

Since the pioneering studies of Thomas Hunt Morgan and coworkers at the dawn of the twentieth century, Drosophila melanogaster and its sister species have tremendously contributed to unveil the rules underlying animal genetics, development, behavior, evolution, and human disease. Recent advances in DNA sequencing technologies launched Drosophila into the post-genomic era and paved the way for unprecedented comparative genomics investigations. The complete sequencing and systematic comparison of the genomes from 12 Drosophila species represents a milestone achievement in modern biology, which allowed a plethora of different studies ranging from the annotation of known and novel genomic features to the evolution of chromosomes and, ultimately, of entire genomes. Despite the efforts of countless laboratories worldwide, the vast amount of data that were produced over the past 15 years is far from being fully explored.In this chapter, we will review some of the bioinformatic approaches that were developed to interrogate the genomes of the 12 Drosophila species. Setting off from alignments of the entire genomic sequences, the degree of conservation can be separately evaluated for every region of the genome, providing already first hints about elements that are under purifying selection and therefore likely functional. Furthermore, the careful analysis of repeated sequences sheds light on the evolutionary dynamics of transposons, an enigmatic and fascinating class of mobile elements housed in the genomes of animals and plants. Comparative genomics also aids in the computational identification of the transcriptionally active part of the genome, first and foremost of protein-coding loci, but also of transcribed nevertheless apparently noncoding regions, which were once considered "junk" DNA. Eventually, the synergy between functional and comparative genomics also facilitates in silico and in vivo studies on cis-acting regulatory elements, like transcription factor binding sites, that due to the high degree of sequence variability usually impose increased challenges for bioinformatics approaches.