New Taxonomic Arrangement of Dicranella s.l. and Aongstroemia s.l. (Dicranidae, Bryophyta).

The recent molecular phylogenetic study of the families Aongstroemiaceae and Dicranellaceae, which resolved the genera Aongstroemia and Dicranella as polyphyletic, indicated the need for changes in their circumscription and provided new morphological evidence to support the formal description of newly recognized lineages. Following up on these results, the present study adds another molecular marker, the highly informative trnK-psbA region, to a subset of previously analyzed taxa and presents molecular data from newly analyzed austral representatives of Dicranella and collections of Dicranella-like plants from North Asia. The molecular data are linked with morphological traits, particularly the leaf shape, tuber morphology, and capsule and peristome characters. Based on this multi-proxy evidence, we propose three new families (Dicranellopsidaceae, Rhizogemmaceae, and Ruficaulaceae) and six new genera (Bryopalisotia, Calcidicranella, Dicranellopsis, Protoaongstroemia, Rhizogemma, and Ruficaulis) to accommodate the described species according to the revealed phylogenetic affinities. Additionally, we amend the circumscriptions of the families Aongstroemiaceae and Dicranellaceae, as well as the genera Aongstroemia and Dicranella. In addition to the monotypic Protoaongstroemia that contains the newly described dicranelloid plant with a 2-3-layered distal leaf portion from Pacific Russia, P. sachalinensis, Dicranella thermalis is described for a D. heteromalla-like plant from the same region. Fourteen new combinations, including one new status change, are proposed.

An Insight into the Biology of the Rare and Peculiar Moss Pterygoneurum sibiricum (Pottiaceae): A Conservation Physiology Approach.

The biological features of the recently described peculiar and rare pottioid moss species Pterygoneurum sibiricum have been studied. A conservation physiology approach through in vitro axenic establishment and laboratory-controlled tests was applied to learn more about its development, physiology, and ecology. Additionally, ex situ collection for this species was established, and a micropropagation methodology was developed. The results obtained clearly document its reaction to salt stress in contrast to its sibling bryo-halophyte species P. kozlovii. The reaction to exogenously applied plant growth regulators, auxin and cytokinin, can be used in the different moss propagation phases of this species or for target structure production and development. Inference to the poorly known ecology of this species should also help in recent species records, and thus improve knowledge about its distribution and conservation.

Need for split: integrative taxonomy reveals unnoticed diversity in the subaquatic species of Pseudohygrohypnum (Pylaisiaceae, Bryophyta).

We present an integrative molecular and morphological study of subaquatic representatives of the genus Pseudohygrohypnum (Pylaisiaceae, Bryophyta), supplemented by distribution modelling of the revealed phylogenetic lineages. Phylogenetic analyses of nuclear and plastid datasets combined with the assemble species by automatic partitioning (ASAP) algorithm revealed eight distinct species within the traditionally circumscribed P. eugyrium and P. subeugyrium. These species are therefore yet another example of seemingly widely distributed taxa that harbour molecularly well-differentiated lineages with narrower distribution ranges. Studied accessions that were previously assigned to P. eugyrium form three clearly allopatric lineages, associated with temperate regions of Europe, eastern North America and eastern Asia. Remarkably, accessions falling under the current morphological concept of P. subeugyrium were shown to be even more diverse, containing five phylogenetic lineages. Three of these lineages occur under harsh Asian continental climates from cool-temperate to Arctic regions, while the remaining two, referred to P. subeugyrium s.str. and P. purpurascens, have more oceanic North Atlantic and East Asian distributions. Niche identity and similarity tests suggested no similarity in the distributions of the phylogenetically related lineages but revealed the identity of two East Asian species and the similarity of two pairs of unrelated species. A morphological survey confirmed the distinctness of all eight phylogenetic lineages, requiring the description of five new species. Pseudohygrohypnum appalachianum and P. orientale are described for North American and East Asian plants of P. eugyrium s.l., while P. sibiricum, P. subarcticum and P. neglectum are described for the three continental, predominantly Asian lineages of P. subeugyrium s.l. Our results highlight the importance of nontropical Asia as a center of bryophyte diversity. Phylogenic dating suggests that the diversification of subaquatic Pseudohygrohypnum lineages appeared in late Miocene, while mesophilous species of the genus split before Miocene cooling, in climatic conditions close to those where the ancestor of Pseudohygrohypnum appeared. We speculate that radiation of the P. subeugyrium complex in temperate Asia might have been driven by progressive cooling, aridification, and increases in seasonality, temperature and humidity gradients. Our results parallel those of several integrative taxonomic studies of North Asian mosses, which have resulted in a number of newly revealed species. These include various endemics from continental areas of Asia suggesting that the so-called Rapoport's rule of low diversity and wide distribution range in subpolar regions might not be applicable to bryophytes. Rather, the strong climatic oscillations in these regions may have served as a driving force of speciation and niche divergence.

MHA Herbarium: Collections of mosses from Yana-Indigirka Region, Yakutia, Russia.

BACKGROUND: The Skvortsov Herbarium of the Tsitsin Main Botanical Garden, Russian Academy of Sciences (MHA) in the 1945-1980s dealt with vascular plants and only scattered occasional collections of bryophytes and lichens were accumulated there without special arrangement. Since the late 1980s, the bryophyte studies in the MHA Herbarium became permanent and several projects were started since then, including the currently conducted "Moss Flora of Russia". There are many white spots on the map of bryophyte exploration of Russia, but one of the most conspicuous was Yakutia, the largest administrative unit of Russia, covering 3,081,000 km2. Yana-Indigirka Region, originally defined as a floristic region, includes Verkhoyansky Range and some smaller adjacent mountain areas. It is the largest amongst the bryofloristic regions in Russia, but exploration of its territory, which is difficult to access, remains far from complete. NEW INFORMATION: Several expeditions of the Institute for Biological Problems of Cryolithozone, Siberian Branch of Russian Academy of Sciences, and the Main Botanical Garden, Russian Academy of Sciences in 2000-2018 yielded in many bryophyte specimens, partly published in a number of papers. This dataset comprehensively represents the diversity of mosses of the Region. It includes 7,738 records of moss specimens preserved in the MHA Herbarium.

Cell Division Patterns in the Peristomial Layers of the Moss Genus Costesia: Two Hypotheses and a Third Solution.

The Chilean endemic genus Costesia belongs to the Gigaspermaceae, one of the most basal groups of arthrodontous mosses. While none of the species in this family has a peristome, earlier stages of sporophyte development often disclose its basic structure. The study of Costesia sporophytes at the early stages of development was conducted to identify possible similarities with Diphyscium, the genus sister to Gigaspermaceae plus all other arthrodontous mosses in the moss phylogenetic tree. Diphyscium shares a strongly unequal cell division pattern with the Dicranidae. In groups more closely related to Diphyscium, as it is the case of Costesia, this pattern is not known. Our study of Costesia found only irregular presence of slightly unequal cell divisions that may then be considered as a plesiomorphic state in peristomate mosses. The most frequently present pattern revealed in Costesia is common with the Polytrichaceae, a more basal moss group with nematodontous peristomes.

Otopetrin 1 is required for otolith formation in the zebrafish Danio rerio.

Orientation with respect to gravity is essential for the survival of complex organisms. The gravity receptor is one of the phylogenetically oldest sensory systems, and special adaptations that enhance sensitivity to gravity are highly conserved. The fish inner ear contains three large extracellular biomineral particles, otoliths, which have evolved to transduce the force of gravity into neuronal signals. Mammalian ears contain thousands of small particles called otoconia that serve a similar function. Loss or displacement of these structures can be lethal for fish and is responsible for benign paroxysmal positional vertigo (BPPV) in humans. The distinct morphologies of otoconial particles and otoliths suggest divergent developmental mechanisms. Mutations in a novel gene Otopetrin 1 (Otop1), encoding multi-transmembrane domain protein, result in nonsyndromic otoconial agenesis and a severe balance disorder in mice. Here we show that the zebrafish, Danio rerio, contains a highly conserved gene, otop1, that is essential for otolith formation. Morpholino-mediated knockdown of zebrafish Otop1 leads to otolith agenesis without affecting the sensory epithelium or other structures within the inner ear. Despite lack of otoliths in early development, otolith formation partially recovers in some fish after 2 days. However, the otoliths are malformed, misplaced, lack an organic matrix, and often consist of inorganic calcite crystals. These studies demonstrate that Otop1 has an essential and conserved role in the timing of formation and the size and shape of the developing otolith.

Molecular mechanisms underlying ectopic otoconia-like particles in the endolymphatic sac of embryonic mice.

Otoconin-90, the principal otoconial matrix protein, provided a tool to investigate the molecular mechanism of otoconial morphogenesis. The endolymphatic sac of the embryonic chick and guinea pig contain otoconia. Here, we show that the embryonic mouse transiently expresses ectopic otoconia in the endolymphatic sac. Massive precipitate of otoconin-90-positive material is detectable in the lumen of the endolymphatic sac between embryonic day 14.5 and 17.5 with frequent accretion into more heavily staining otoconia-like particles. Otoconin-90 was also localized at the surface and the interior of epithelial cells lining the endolymphatic sac as well as incorporated into free floating cells. In contrast, in situ hybridization failed to detect mRNA in the endolymphatic duct and sac, even though the adjacent nonsensory vestibular structures are heavily stained. Because of ample expression of otoconin-90 protein in the absence of the corresponding mRNA, we conclude that the luminal otoconin-90 is imported via longitudinal flow from the vestibular compartments, where both mRNA and protein are strongly expressed. Because of absence of mRNA, the expression of the corresponding protein by the epithelia lining the endolymphatic sac can only be explained by a resorptive process, as previously proposed on the basis of the movement of luminal macromolecules. The data do not support the previous hypothesis that the transient expression of otoconia-like particles of the endolymphatic sac represents a vestigial phenomenon from the amphibian stage, since amphibia express ample mRNA encoding otoconin-22 in the endolymphatic sac system.

The cochlear F-box protein OCP1 associates with OCP2 and connexin 26.

OCP1 and OCP2 are the most abundant proteins in the organ of Corti. Their distributions map identically to the epithelial gap-junction system, which unites the supporting cell population. Sequence data imply that OCP1 and OCP2 are subunits of an SCF E3 ubiquitin ligase. Consistent with that hypothesis, electrophoretic mobility-shift assays and pull-down assays with immobilized OCP1 demonstrate the formation of an OCP1-OCP2 complex. Sedimentation equilibrium data indicate that the complex is heterodimeric. The coincidence of the OCP1-OCP2 distribution and the epithelial gap-junction system suggests that one or more connexin isoforms may be targets of an SCF(OCP1) complex. Significantly, immobilized OCP1 binds (35)S-labeled connexin 26 (Cx26) produced by in vitro transcription-translation. Moreover, Cx26 can be co-immunoprecipitated from extracts of the organ of Corti by immobilized anti-OCP1, implying that OCP1 and Cx26 may associate in vivo. Given that lesions in the Cx26 gene (GJB2) are the most common cause of hereditary deafness, the OCP1-Cx26 interaction has substantial biomedical relevance.

Toward an understanding of cochlear homeostasis: the impact of location and the role of OCP1 and OCP2.

The central role of the supporting cell population, or epithelial support complex (ESC), in cochlear homeostasis has gained general acceptance. That the details of this role may vary markedly with location, however, remains poorly appreciated. For example, the K+ recirculation pathway may well be dictated by position along the cochlear axis: a perilymphatic route near the apex and a transcellular one near the base. The ESC expresses very high levels of OCP1 and OCP2, now known to be components of a novel, organ of Corti (OC)-specific SCF ubiquitin ligase (SCF(OCP1)). In the SCF(OCP1) cnmplex, OCP1 presumably binds selected protein targets, positioning them for ubiquitination. The recent demonstration that recombinant OCP1 interacts non-covalently with Cx26 suggests that the connexins may be target proteins for SCF(OCP1). Although ubiquitination has classically been viewed as a signal for subsequent destruction by the 26S proteasome, the energy-limited state of the OC prompts consideration of alternative fates, e.g. reversible internalization. The ESC also expresses several components of the Wingless/Wnt signaling pathway. Significantly, two of the gap-junction proteins expressed in the OC, Cx43 and Cx30, are known targets of the Wnt pathway. On the basis of these observations, a working hypothesis is proposed wherein the Wnt pathway activates connexin expression, while OCP1 regulates its degradation.

Non-syndromic vestibular disorder with otoconial agenesis in tilted/mergulhador mice caused by mutations in otopetrin 1.

Otoconia are biominerals within the utricle and saccule of the inner ear that are critical for the perception of gravity and linear acceleration. The classical mouse mutant tilted (tlt) and a new allele, mergulhador (mlh), are recessive mutations that affect balance by impairing otoconial morphogenesis without causing collateral deafness. The mechanisms governing otoconial biosynthesis are not known. Here we show that tlt and mlh are mutant alleles of a novel gene (Otopetrin 1, Otop1), encoding a multi-transmembrane domain protein that is expressed in the macula of the developing otocyst. Both mutants carry single point mutations leading to non-conservative amino acid substitutions that affect two putative transmembrane (TM) domains (tlt, Ala(151)-->Glu in TM3; mlh, Leu(408)-->Gln in TM8). Otop1 and Otop1-like paralogues, Otop2 and Otop3, define a new gene family with homology to the C. elegans and D. melanoganster DUF270 genes.