Expression of acylamidase gene in Rhodococcus erythropolis strains

The expression of a new acylamidase gene from R. erythropolis TA37 was studied in Rhodococcus erythropolis strains. This acylamidase, as a result of its unique substrate specificity, can hydrolyse N-substituted amides (4′-nitroacetanilide, N-isopropylacrylamide, N′N-dimethylaminopropylacrylamide). A new expression system based on the use of the promoter region of nitrile hydratase genes from R. rhodochrous M8 was created to achieve constitutive synthesis of acylamidase in R. erythropolis cells. A fourfold improvement in the acylamidase activity of recombinant R. erythropolis cells as compared with the parent wild-type strain was obtained through the use of the new expression system.     

A new species of <Emphasis Type="Italic">Paroxyaena</Emphasis> (Hyaenodontidae,Creodonta) from phosphorites of Quercy,Late Eocene,France

An almost complete skull without a lower jaw of Paroxyaena pavlovi sp. nov. (Pterodontinae) is described. A new tribe, Paroxyaenini tribe nov., is established. The round foramen and orbital fissure of Paroxyaenini are completely fused, whereas those of Pterodontini are separate. The deciduous teeth of Paroxyaena are described for the first time.     

Extensive and evolutionarily persistent mitochondrial tRNA editing in Velvet Worms (phylum Onychophora)

Mitochondrial genomes of onychophorans (velvet worms) present an interesting problem: Some previous studies reported them lacking several transfer RNA (tRNA) genes, whereas others found that all their tRNA genes were present but severely reduced. To resolve this discrepancy, we determined complete mitochondrial DNA (mtDNA) sequences of the onychophorans Oroperipatus sp. and Peripatoides sympatrica as well as cDNA sequences from 14 and 10 of their tRNAs, respectively. We show that tRNA genes in these genomes are indeed highly reduced and encode truncated molecules, which are restored to more conventional structures by extensive tRNA editing. During this editing process, up to 34 nucleotides are added to the tRNA sequences encoded in Oroperipatus sp. mtDNA, rebuilding the aminoacyl acceptor stem, the TΨC arm, and in some extreme cases, the variable arm and even a part of the anticodon stem. The editing is less extreme in P. sympatrica in which at least a part of the TΨC arm is always encoded in mtDNA. When the entire TΨC arm is added de novo in Oroperipatus sp., the sequence of this arm is either identical or similar among different tRNA species, yet the sequences show substantial variation for each tRNA. These observations suggest that the arm is rebuilt, at least in part, by a template-independent mechanism and argue against the alternative possibility that tRNA genes or their parts are imported from the nucleus. By contrast, the 3' end of the aminoacyl acceptor stem is likely restored by a template-dependent mechanism. The extreme tRNA editing reported here has been preserved for >140 My as it was found in both extant families of onychophorans. Furthermore, a similar type of tRNA editing may be present in several other groups of arthropods, which show a high degree of tRNA gene reduction in their mtDNA.     

Pleistocene foxes (Vulpes,Canidae, Carnivora) from the Taurida Cave,Crimea

Doklady Biological Sciences - A mandible fragment and four isolated teeth of the fossil foxes, Vulpes alopecoides (Del Campana, 1913), Vulpes cf. vulpes (Linnaeus, 1758) and Vulpes sp., are...     

Erratum to: A New Mass Burial of Cave Bears (Carnivora,Ursidae, Ursus kanivetz,Vereshchagin, 1973) from the Middle Urals

Doklady Biological Sciences - An Erratum to this paper has been published: https://doi.org/10.1134/S0012496621050112     

Early Pleistocene Lynx issiodorensis (Felidae,Carnivora) from the Taurida Cave,Crimea

Doklady Biological Sciences - The cranial and mandibular remains of two adult individuals of Lynx issiodorensis (Croizet et Jobert, 1828) are described from the Early Pleistocene locality of the...     

Rapidly evolving mitochondrial genome and directional selection in mitochondrial genes in the parasitic wasp nasonia (hymenoptera: pteromalidae)

We sequenced the nearly complete mtDNA of 3 species of parasitic wasps, Nasonia vitripennis (2 strains), Nasonia giraulti, and Nasonia longicornis, including all 13 protein-coding genes and the 2 rRNAs, and found unusual patterns of mitochondrial evolution. The Nasonia mtDNA has a unique gene order compared with other insect mtDNAs due to multiple rearrangements. The mtDNAs of these wasps also show nucleotide substitution rates over 30 times faster than nuclear protein-coding genes, indicating among the highest substitution rates found in animal mitochondria (normally <10 times faster). A McDonald and Kreitman test shows that the between-species frequency of fixed replacement sites relative to silent sites is significantly higher compared with within-species polymorphisms in 2 mitochondrial genes of Nasonia, atp6 and atp8, indicating directional selection. Consistent with this interpretation, the Ka/Ks (nonsynonymous/synonymous substitution rates) ratios are higher between species than within species. In contrast, cox1 shows a signature of purifying selection for amino acid sequence conservation, although rates of amino acid substitutions are still higher than for comparable insects. The mitochondrial-encoded polypeptides atp6 and atp8 both occur in F0F1ATP synthase of the electron transport chain. Because malfunction in this fundamental protein severely affects fitness, we suggest that the accelerated accumulation of replacements is due to beneficial mutations necessary to compensate mild-deleterious mutations fixed by random genetic drift or Wolbachia sweeps in the fast evolving mitochondria of Nasonia. We further propose that relatively high rates of amino acid substitution in some mitochondrial genes can be driven by a "Compensation-Draft Feedback"; increased fixation of mildly deleterious mutations results in selection for compensatory mutations, which lead to fixation of additional deleterious mutations in nonrecombining mitochondrial genomes, thus accelerating the process of amino acid substitutions.