New observations and reinterpretation on the enigmatic taxon Colombitherium (?Pyrotheria,Mammalia) from Colombia

Abstract: The controversial taxon Colombitherium tolimense (Mammalia) (probably Late Eocene in age) from Colombia, although known for nearly 40 years, still bears much mystery. Aside from the problematic ordinal attribution of the holotype and only specimen, its determination as an upper or lower jaw remains a highly debated issue. New observations include the presence of a contact facet on the distal face of the most posterior tooth, which indicates that the fragmentary jaw preserves three premolars and two molars; the M3, unpreserved but present, being most probably reduced. This new interpretation completely fits the morphology of the teeth. Furthermore, the shape of these latter and the deeper wear encompassed by their lingual part relative to the labial one is typical of upper dentition. This is in agreement with the internal curving of the roots of the anterior premolars and with several other arguments that lead interpreting the holotype of C. tolimense as a maxillary bearing P2‐M2. This new interpretation deepens the morphological gap between Colombitherium and other pyrotherians (except Proticia) and challenges further its referral to Pyrotheria. The peculiar morphology of Colombitherium relative to other pyrotherians is indeed striking. In fact, Colombitherium has nothing in common with pyrotherians but bilophodont cheek teeth, a feature largely widespread in placental mammals. It is here referred to ?Pyrotheria until additional evidence of its relationships is known. Associated with the putative removal of Proticia from Pyrotheria as argued by some authors, the hypothetical removal of Colombitherium from the order would adjust the widely accepted assumption that the pyrotherian bilophodont cheek teeth originated from bunodont cheek teeth. It would also make an origin from lophodont forms plausible. This in turn would have critical relevance, especially to the hypothesis that pyrotherians are notoungulates.     

Azygos Vein Lead Implantation For High Defibrillation Thresholds In Implantable Cardioverter Defibrillator Placement

Evaluation of defibrillation threshold is a standard of care during implantation of implantable cardioverter defibrillator. High defibrillation thresholds are often encountered and pose a challenge to electrophysiologists to improve the defibrillation threshold. We describe a case series where defibrillation thresholds were improved after implanting a defibrillation lead in the azygos vein.     

Relationships of eelpouts of genus Zoarces (Zoarcidae, Pisces) inferred from molecular genetic and morphological data

Molecular genetic and morphological analysis of eelpouts of the genus Zoarces was carried out. Based on the mitochondrial DNA sequence variation, haplotypes of notched-fin eelpout, Z. elogatus, more closely related Fedorov eelpout, Z. fedorovi, and common eelpout, Z. viviparus, as well as of Andriyashev eelpout, Z. andriashevi, were grouped in one macrocluster. Haplotypes of American eelpout, Z. americanus, and blotched eelpout, Z. gillii, clustered separately from other species. The genetic differences between Z. gillii and the other eelpout species were very high for within-genus comparisons, constituting 7.62%. Species divergence in terms of morphological characters was generally consistent with molecular genetic data and confirmed distinct isolation of American eelpout, and especially of blotched eelpout.     

Feather ornaments are dynamic traits in the Great Tit Parus major

In behavioural studies it has been common to quantify plumage colours or ornaments over a range of dates and link them to fitness characteristics without accounting for seasonal changes in these traits. Such changes are likely to be widespread among birds, yet we lack assessments of this variability within individuals. We studied both within‐ and between‐individual temporal changes in Great Tit Parus major ornaments, specifically the melanin‐based black breast stripe and the pigment‐free white cheek patch. During the non‐breeding season both ornaments varied. In juveniles and adult females, the area of the breast stripe first rose and then, from near the end of December, decreased. In adult males there was a linear decrease. In the cheek patch, the irregularity of the cheek borders showed either a linear (adults) or a non‐linear (juveniles) increase as the season progressed. In individuals repeatedly sampled during the same winter, the decrease in the size of the breast stripe was larger for males than females and there was an overall decrease in the regularity of the cheek borders. There was no relationship between the size of the breast stripe and the white cheek patch irregularities or the cheek patch area. These results imply that more attention should be paid to quantification, within individuals, of the components of expression of phenotypic traits. In addition, we suggest that further research should focus on explaining the causes and functions of ornament change.     

Risk Factors and Mechanisms of Cardiovascular Diseases in Posttraumatic Stress Disorder Model in Wistar Rats as Dependent on Stress Resistance and Age

Doklady Biological Sciences - The article focuses on the pathogenetic mechanisms of posttraumatic stress disorder (PTSD), which is associated with psychological stress because of the coronavirus...