FRASNIAN (UPPER DEVONIAN) BRACHIOPODS FROM ARMENIA: BIOSTRATIGRAPHIC AND PALAEOBIOGEOGRAPHIC IMPLICATIONS

An assemblage of seven brachiopod species belonging to the orders Rhynchonellida, Atrypida and Spiriferida are studied from three localities (Ertych, Djravank and Noravank) of Central Armenia. The examined material is recovered from shallow water nodular limestones and provides insights into the diversity of Frasnian brachiopods on that part of the northern margin of Gondwana preserved within the South Armenian Block. The revision of Atrypa (Planatrypa) ertichensis, a biostratigraphically significant species for the Frasnian of the Lesser Caucasus (Armenia and Nakhichevan), revealed the presence of frills, an ornamental feature rarely observed in Atrypa (Planatrypa) representatives and considered as unknown in this species. Taxonomic discussion also involves the selection of neotypes for Ripidiorhynchus gnishikensis and A. (P.) ertichensis. The newly described taxon, Angustisulcispirifer arakelyani n. gen., n. sp., appears to be one of the most biostratigraphically important species for the Frasnian of Armenia. The size variability of Cyphoterorhynchus koraghensis and Desquamatia (Seratrypa) abramianae is documented quantitatively for the first time and it shows a continuous and progressive growth without any distinct groupings; the former is a palaeobiogeographically important species for the Frasnian strata of the northern Gondwana margin. Pending the revision of the Pakistani and Iranian material ascribed to C. koraghensis, that may include several subspecies, a plaster cast of its lectotype from the Frasnian of Kuragh in Chitral (northwest Pakistan) and the holotype as well as one of the paratypes of Cyphoterorhynchus koraghensis interpositus from the Frasnian Bahram Formation of the Ozbak-Kuh region in eastern Iran are illustrated herein. Finally, a new Frasnian brachiopod zone, namely the Ripidiorhynchus gnishikensis–Angustisulcispirifer arakelyani assemblage Zone is here introduced for the studied sections. Although its base and top cannot be identified, it is constrained to the Frasnian based on conodonts identified in the Djravank section. It may be considered as a partly lateral equivalent of the Cyrtospirifer subarchiaci–Cyphoterorhynchus arpaensis brachiopod Zone established in Nakhichevan

Ancient gene duplications have shaped developmental stage-specific expression in Pristionchus pacificus

BACKGROUND: The development of multicellular organisms is accompanied by gene expression changes in differentiating cells. Profiling stage-specific expression during development may reveal important insights into gene sets that contributed to the morphological diversity across the animal kingdom. RESULTS: We sequenced RNA-seq libraries throughout a developmental timecourse of the nematode Pristionchus pacificus. The transcriptomes reflect early larval stages, adult worms including late larvae, and growth-arrested dauer larvae and allowed the identification of developmentally regulated gene clusters. Our data reveals similar trends as previous transcriptome profiling of dauer worms and represents the first expression data for early larvae in P. pacificus. Gene expression clusters characterizing early larval stages show most significant enrichments of chaperones, while collagens are most significantly enriched in transcriptomes of late larvae and adult worms. By combining expression data with phylogenetic analysis, we found that developmentally regulated genes are found in paralogous clusters that have arisen through lineage-specific duplications after the split from the Caenorhabditis elegans branch. CONCLUSIONS: We propose that gene duplications of developmentally regulated genes represent a plausible evolutionary mechanism to increase the dosage of stage-specific expression. Consequently, this may contribute to the substantial divergence in expression profiles that has been observed across larger evolutionary time scales

Transcriptional adaptation in caenorhabditis elegans

Transcriptional adaptation is a recently described phenomenon by which a mutation in one gene leads to the transcriptional modulation of related genes, termed adapting genes. At the molecular level, it has been proposed that the mutant mRNA, rather than the loss of protein function, activates this response. While several examples of transcriptional adaptation have been reported in zebrafish embryos and in mouse cell lines, it is not known whether this phenomenon is observed across metazoans. Here we report transcriptional adaptation in C. elegans, and find that this process requires factors involved in mutant mRNA decay, as in zebrafish and mouse. We further uncover a requirement for Argonaute proteins and Dicer, factors involved in small RNA maturation and transport into the nucleus. Altogether, these results provide evidence for transcriptional adaptation in C. elegans, a powerful model to further investigate underlying molecular mechanisms.publishedVersio

RECONSTRUCTING NORTH GONDWANAN VEGETATION FROM THE MIDDLE DEVONIAN DEPOSITS OF ARMENIA

peer reviewe

Nicotine Protects Kidney from Renal Ischemia/Reperfusion Injury through the Cholinergic Anti-Inflammatory Pathway

Kidney ischemia/reperfusion injury (I/R) is characterized by renal dysfunction and tubular damages resulting from an early activation of innate immunity. Recently, nicotine administration has been shown to be a powerful inhibitor of a variety of innate immune responses, including LPS-induced toxaemia. This cholinergic anti-inflammatory pathway acts via the α7 nicotinic acetylcholine receptor (α7nAChR). Herein, we tested the potential protective effect of nicotine administration in a mouse model of renal I/R injury induced by bilateral clamping of kidney arteries. Renal function, tubular damages and inflammatory response were compared between control animals and mice receiving nicotine at the time of ischemia. Nicotine pretreatment protected mice from renal dysfunction in a dose-dependent manner and through the α7nAChR, as attested by the absence of protection in α7nAChR-deficient mice. Additionally, nicotine significantly reduced tubular damages, prevented neutrophil infiltration and decreased productions of the CXC-chemokine KC, TNF-α and the proinflammatory high-mobility group box 1 protein. Reduced tubular damage in nicotine pre-treated mice was associated with a decrease in tubular cell apoptosis and proliferative response as attested by the reduction of caspase-3 and Ki67 positive cells, respectively. All together, these data highlight that nicotine exerts a protective anti-inflammatory effect during kidney I/R through the cholinergic α7nAChR pathway. In addition, this could provide an opportunity to overcome the effect of surgical cholinergic denervation during kidney transplantation

Cholinergic receptor pathways involved in apoptosis, cell proliferation and neuronal differentiation

Acetylcholine (ACh) has been shown to modulate neuronal differentiation during early development. Both muscarinic and nicotinic acetylcholine receptors (AChRs) regulate a wide variety of physiological responses, including apoptosis, cellular proliferation and neuronal differentiation. However, the intracellular mechanisms underlying these effects of AChR signaling are not fully understood. It is known that activation of AChRs increase cellular proliferation and neurogenesis and that regulation of intracellular calcium through AChRs may underlie the many functions of ACh. Intriguingly, activation of diverse signaling molecules such as Ras-mitogen-activated protein kinase, phosphatidylinositol 3-kinase-Akt, protein kinase C and c-Src is modulated by AChRs. Here we discuss the roles of ACh in neuronal differentiation, cell proliferation and apoptosis. We also discuss the pathways involved in these processes, as well as the effects of novel endogenous AChRs agonists and strategies to enhance neuronal-differentiation of stem and neural progenitor cells. Further understanding of the intracellular mechanisms underlying AChR signaling may provide insights for novel therapeutic strategies, as abnormal AChR activity is present in many diseases

Опыт применения вено-венозной экстракорпоральной мембранной оксигенации у беременной с тяжелым острым респираторным дистресс-синдромом, вызванным вирусом SARS-CoV-2

 Pregnant women occupy a special place in the incidence structure of the new coronavirus infection COVID -19. Taking into account the likelihood of a more severe course of acute respiratory syndrome (ARDS) in this group, it is worth remembering the possibility of timely use of veno-venous extracorporeal membrane oxygenation (IV ECMO) in order to correct life-threatening hypoxia. At the Lapino Clinical Hospital, a cesarean section was successfully performed in a 37-year-old female patient at 20–21 weeks of gestation against the background of IV ECMO with further decannulation  and discharge from the hospital.  Особое место в структуре заболеваемости новой коронавирусной инфекцией COVID-19 занимают беременные. Принимая во внимание вероятность более тяжелого течения острого респираторного синдрома  (ОРДС) у данной группы, стоит помнить о возможности своевременного  применения вено-венозной экстракорпоральной мембранной оксигенации  (ВВ ЭКМО) с целью коррекции жизнеугрожающей гипоксии. В клиническом госпитале «Лапино» было успешно выполнено кесарево сечение у пациентки 37 лет на 20–21-й неделе гестации на фоне ВВ ЭКМО с дальнейшей деканюляцией и выпиской из стационара.

Gene(s) and individual feeding behavior: Exploring eco-evolutionary dynamics underlying left-right asymmetry in the scale-eating cichlid fish Perissodus microlepis

The scale‐eating cichlid fish Perissodus microlepis is a textbook example of bilateral asymmetry due to its left or right‐bending heads and of negative frequency‐dependent selection, which is proposed to maintain this stable polymorphism. The mechanisms that underlie this asymmetry remain elusive. Several studies had initially postulated a simple genetic basis for this trait, but this explanation has been questioned, particularly by reports observing a unimodal distribution of mouth shapes. We hypothesize that this unimodal distribution might be due to a combination of genetic and phenotypically plastic components. Here, we expanded on previous work by investigating a formerly identified candidate SNP associated to mouth laterality, documenting inter‐individual variation in feeding preference using stable isotope analyses, and testing their association with mouth asymmetry. Our results suggest that this polymorphism is influenced by both a polygenic basis and inter‐individual non‐genetic variation, possibly due to feeding experience, individual specialization, and intraspecific competition. We introduce a hypothesis potentially explaining the simultaneous maintenance of left, right, asymmetric and symmetric mouth phenotypes due to the interaction between diverse eco‐evolutionary dynamics including niche construction and balancing selection. Future studies will have to further tease apart the relative contribution of genetic and environmental factors and their interactions in an integrated fashion