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Nuclear genes of euglenids and marine diplonemids harbor atypical, nonconventional introns which are not observed in the genomes of other eukaryotes. Nonconventional introns do not have the conserved borders characteristic for spliceosomal introns or the sequence complementary to U1 snRNA at the 5' end. They form a stable secondary structure bringing together both exon/intron junctions, nevertheless, this conformation does not resemble the form of self-splicing or tRNA introns. In the genes studied so far, frequent nonconventional introns insertions at new positions have been observed, whereas conventional introns have been either found at the conserved positions, or simply lost. In this work, we examined the order of intron removal from Euglena gracilis transcripts of the tubA and gapC genes, which contain two types of introns: nonconventional and spliceosomal. The relative order of intron excision was compared for pairs of introns belonging to different types. Furthermore, intermediate products of splicing were analyzed using the PacBio Next Generation Sequencing system. The analysis led to the main conclusion that nonconventional introns are removed in a rapid way but later than spliceosomal introns. Moreover, the observed accumulation of transcripts with conventional introns removed and nonconventional present may suggest the existence of a time gap between the two types of splicing.

The endangered Spitsbergen stock of bowhead whales ( Balaena mysticetus ) has once been large with up to estimated 100,000 individuals. Genetic diversity of the extant Spitsbergen stock is unknown. We present 10 complete mitochondrial genomes of heterochronous ancient bowhead whale samples from Svalbard ( 14 C age estimate range: 215–8885 years) obtained via NGS of total genomic DNA extracts. The ten mitogenomes differed by nucleotide substitutions and/or indels, and there was a total of 160 variable positions. The average nucleotide diversity was π = 0.0029. There was no statistically significant correlation between genetic divergence and time.

The northern pike (Esox lucius L.) is a commercially important fish that forms freshwater and brackish populations. While the first ecotype is still quite abundant, the second has suffered rapid declines in recent years. Populations inhabiting the Baltic coastal waters of Poland have been supported by stocking programs since the late 1990s. This study describes a multiplex microsatellite (msDNA) assay consisting of 12 loci divided conveniently into two amplification sets (Elu78, Elu87, B451, Elu37, B457, B16, B25, and Elu19, Elu76, B422, Elu2, Elu7). The assay was optimized for genetic analyses of freshwater and brackish populations. These multiplexes were successfully executed to obtain the genetic profiles of 668 individuals from 16 populations (Poland and Germany). The average number of alleles was equal to 10.4, whereas the observed heterozygosity per locus ranged from 0.18 to 0.89, with the average value of 0.64. The probability of the identity of the marker sets indicated the high power of identification of unique genotypes. Therefore, this molecular tool can be used to describe the genetic variability of populations, select the proper source of breeding material, and monitor the progress of stocking efforts in genetic conservation projects of this species.

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