Chemico-structural evolution of linguloid brachiopod shells

Chemico-structures of shells representing all families presently assigned to the Linguloidea have undergone significant transformations since the Early Cambrian. Superficial hemispherical to hemi-ellipsoidal pits on the larval and/or mature shells are interpreted as casts of deformable, membrane-bound vesicles of mucus or rigid vesicles of glycoproteins or GAGs with thickened coats. Flat-bottomed, sub-circular imprints characterize acrotheloids and many acrotretides, and could be impressions of biconvex tablets of apatite like those exocytosed within the primary layer of the obolid ‘Lingulella’? antiquissima, whilst the rhomboidal imprints of the Paterula shell could have held tablets of proteinaceous silica like those of living discinid larvae. The ancestral fabric of the linguloid secondary layer was probably composed of rubbly and virgose sets, but trellised rods of apatite (baculation) are characteristic of most linguloids and also acrotheloids. This condition was suppressed in shells identified as ‘Lingula’ from at least the Early Carboniferous to the present day. In early Palaeozoic acrotretides and lingulellotretids, columnar and camerate fabrics evolved in place of baculation. Baculation in Discinisca tenuis and Glottidia pyramidata is associated with the amino acids glutamic acid, glycine, alanine, arginine and proline which may be components of an organic polymer axial to baculate accretion.     

Carboniferous biogeography of the bryozoan Archimedes in North America

The fenestrate bryozoan genus Archimedes apparently originated and then diversified in Early Carboniferous seas of eastern North America. Its highest species richness and greatest abundance are reached in uppermost Lower to lowest Upper Carboniferous (Chesterian) rocks of eastern North America. Following the unconformity that marks the mid‐Carboniferous eustatic event, however, it is known in North America only in Upper Carboniferous basinal deposits of the Oquirrh Mountains and in nearby regions of Utah and Nevada. It is hypothesized that Archimedes’ life‐history patterns caused the biogeographical change: dependence on fragmentation as a means of recruitment did not allow Archimedes to keep up with its rapidly migrating preferred back‐barrier environment during the numerous eustatic transgressive and regressive cycles that caused the shoreline to sweep across North America during the Late Carboniferous. The persistence of Archimedes in the Oquirrh Basin and vicinity is inferred to have resulted from its preferred back‐barrier environment migrating only locally along the relatively steep basinal slope present there during the Late Carboniferous eustatic cycles.     

The coarse wrinkle layer of Palaeozoic ammonoids: new evidence from the Early Carboniferous of Morocco

The wrinkle layer is a dorsal shell structure occurring in a number of ammonoids, but its function is still debated. Here, we describe, from Moroccan material of the Early Carboniferous species Maxigoniatites saourensis (Pareyn, 1961 ), the most conspicuous wrinkle layer known within the Ammonoidea. This additional shell layer occurs in the ventrolateral portion of the adult body chamber and forms continuous lamellae, which range about two millimetres into the lumen of the body chamber. Possible functions are discussed and the most likely interpretation for the structure is ‘fabricational noise’, which is related to the coarsening of the shell ornament of the terminal body chamber.     

The isolation and identification of rhubarb viruses occurring in Britain

Virus-like symptoms were common in British crops of rhubarb. All plants tested of the three main varieties, ‘Timperley Early’, ‘Prince Albert’ and ‘Victoria’, were virus-infected. Turnip mosaic virus and a severe isolate of arabis mosaic virus (AMV) were obtained from ‘Timperley Early’; and ‘Prince Albert’ contained turnip mosaic virus, cherry leaf roll virus (CLRV), a mild isolate of AMV and, infrequently, cucumber mosaic virus (CMV). The main commercial variety ‘Victoria’ contained turnip mosaic virus, CLRV, a mild isolate of AMV and, infrequently, strawberry latent ringspot virus (SLRV). All the viruses were identified serologically. The rhubarb isolates did not differ markedly from other isolates of these viruses in herbaceous host reactions, properties in vitro or particle size and shape. A rhubarb isolate of CLRV was distinguished serologically from a cherry isolate of the virus. Turnip mosaic virus, CLRV and SLRV, were transmitted with difficulty, but AMV isolates were readily transmitted by mechanical inoculation. Turnip mosaic virus was also transmitted to rhubarb by Myzus persicae and Aphis fabae. CLRV was transmitted in 6–8% of the seed of infected ‘Prince Albert’ and ‘Victoria’ rhubarb and in 72% of the seed of infected Chenopodium amaranticolor. Mild isolates of AMV were also transmitted in 10–24% of the seed of infected ‘Prince Albert’ and ‘Victoria’ plants.     

GENETIC STRUCTURE OF THE BLUE RIDGE DUSKY SALAMANDER (DESMOGNATHUS ORESTES): INFERENCES FROM ALLOZYMES, MITOCHONDRIAL DNA, AND BEHAVIOR

Abstract The plethodontid salamander Desmognathus orestes, a member of the D. ochrophaeus species complex, is distributed in southwestern Virginia, eastern Tennessee, and western North Carolina. Previous allozyme analyses indicate that D. orestes consists of two distinct groups of populations (D. orestes‘B’ and D. orestes‘C’) with extensive intergradation and probable gene flow between these two groups. Spatially varying allele frequencies can reflect historical associations, current gene flow, or a combination of population‐level processes. To differentiate among these processes, we use multiple markers to further characterize divergence among populations of D. orestes and assess the degree of intergradation between D. orestes‘B’ and D. orestes‘C’, specifically investigating variation in allozymes, mitochondrial DNA (mtDNA), and reproductive behavior among populations. On a broad scale, the mtDNA genealogies reconstruct haplotype clades that correspond to the species identified from previous allozyme analyses. However, at a finer geographic scale, the distributions of the allozyme and mtDNA markers for D. orestes‘B’ and D. orestes‘C’ are discordant. MtDNA haplotypes corresponding to D. orestes‘B’ are more broadly distributed across western North Carolina than predicted by allozyme data, and the region of intergradation with D. orestes‘C’ indicates asymmetric gene flow of these markers. Asymmetric mating may contribute to observed discordance in nuclear versus cytoplasmic markers. Results support describing D. orestes as a single species and emphasize the importance of using multiple markers to examine fine‐scale patterns and elucidate evolutionary processes affecting gene flow when making species‐level taxonomic decisions.     

A fish and tetrapod fauna from Romer's Gap preserved in Scottish Tournaisian floodplain deposits

The end‐Devonian mass extinction has been framed as a turning point in vertebrate evolution, enabling the radiation of tetrapods, chondrichthyans and actinopterygians. Until very recently ‘Romer's Gap’ rendered the Early Carboniferous a black box standing between the Devonian and the later Carboniferous, but now new Tournaisian localities are filling this interval. Recent work has recovered unexpected tetrapod and lungfish diversity. However, the composition of Tournaisian faunas remains poorly understood. Here we report on a Tournaisian vertebrate fauna from a well‐characterized, narrow stratigraphic interval from the Ballagan Formation exposed at Burnmouth, Scotland. Microfossils suggest brackish conditions and the sedimentology indicates a low‐energy debris flow on a vegetated floodplain. A range of vertebrate bone sizes are preserved. Rhizodonts are represented by the most material, which can be assigned to two taxa. Lungfish are represented by several species, almost all of which are currently endemic to the Ballagan Formation. There are two named tetrapods, Aytonerpeton and Diploradus, with at least two others also represented. Gyracanths, holocephalans, and actinopterygian fishes are represented by rarer fossils. This material compares well with vertebrate fossils from other Ballagan deposits. Faunal similarity analysis using an updated dataset of Devonian–Carboniferous (Givetian–Serpukhovian) sites corroborates a persistent Devonian/Carboniferous split. Separation of the data into marine and non‐marine partitions indicates more Devonian–Carboniferous faunal continuity in non‐marine settings compared to marine settings. These results agree with the latest fossil discoveries and suggest that the Devonian–Carboniferous transition proceeded differently in different environments and among different taxonomic groups.     

Ordovician Calcified Algae and Cyanobacteria, Northern Tarim Basin Subsurface, China

Boreholes between Kuqa and Korla, in the northern Tarim Basin, Xinjiang, penetrated Ordovician marine limestones at depths of 5–6.2km. From three boreholes 54 out of a total of 170 limestone samples contain calcified algae, cyanobacteria and associated Microproblematica. Calcified cyanobacteria (GirvanellaBotomaella, ?Subtifloria) account for 37 per cent of occurrences; green algae (Dasyporelleae and Vermiporella) 28 per cent; Microproblematica (NuiaBevocastriaRothpletzellaHalysis) 20 per cent; and ‘solenoporaceans’ 15 per cent GirvanellaNuia are common in the Early Ordovician deposits, and ‘solenoporaceans’ are abundant in the Mid‐Ordovician. Dasyporelleae and Vermiporella are most abundant in Mid–Late Ordovician samples. Calcified cyanobacteria are common throughout the limestone succession, but particularly in the Mid Ordovician part. MoniliporellaContextaPlexaTexturata, and Villosoporella, hitherto placed in the supposed red algal family Moniliporellaceae Gnilovskaya, are here regarded as dasycladalean green algae. Despite some omissions, this Tarim flora broadly resembles others from Kazakhstan, Baltica and North America, indicating the generally cosmopolitan nature of Ordovician calcified algae and cyanobacteria.     

A HEXAPOD FROM THE EARLY DEVONIAN WINDYFIELD CHERT, RHYNIE, SCOTLAND

Abstract: New diagnostic morphological features discovered following a re‐examination and further preparation of the holotype of Leverhulmia mariae Anderson and Trewin from the Early Devonian (Pragian) Windyfield chert are described and discussed here. The discovery of anterior (thoracic?) leg appendages with attached pretarsal elements comprising a fixed median unguis, a pair of articulated lateral ungues and possible unguitractor plate has allowed us to reclassify this enigmatic fossil as Hexapoda incertae sedis. We interpret the holotype as part of an abdomen bearing at least five pairs of segmented leglets. The condition of the ungues on the anterior appendages is strongly reminiscent of Archaeognatha and Zygentoma (= Thysanura s.s.), and the segmented leglets on the abdomen show similarities with certain fossil ‘apterygotes’ known from the Carboniferous. Leverhulmia is the third hexapod species found in the cherts at Rhynie, the other forms being the collembolan Rhyniella praecursor Hirst and Maulik, and the pterygote insect Rhyniognatha hirsti Tillyard. Showing closer affinities with Archaeognatha and Zygentoma, Leverhulmia may well represent the earliest fossil apterous insect known to date.     

Identification of four distinct ‘Candidatus Phytoplasma’ species in pomegranate trees showing witches' broom,little leaf and yellowing in Jordan,and preliminary insights on their putative insect vectors and reservoir plants

During field surveys conducted in northern Jordan from June to November 2020, phytoplasma-like symptoms, including leaf yellowing/reddening and rolling, little leaf and witches' broom were observed in pomegranate. Disease incidence in 22 surveyed orchards ranged from 30% to 65%. Nested PCR-based amplification of 16S rRNA gene detected phytoplasmas in 17% of collected symptomatic pomegranate trees. Amplicon nucleotide sequence analyses allowed attributing the detected phytoplasmas to ‘Candidatus Phytoplasma solani’, ‘Ca. P. aurantifolia’, ‘Ca. P. asteris’ and ‘Ca. P. ulmi’. These phytoplasmas were found in plants showing specific symptoms and differentially distributed in the considered locations. Additionally, three cicadellids (Macrosteles sexnotatus, Cicadulina bipunctata and Psammotettix striatus) and two non-crop plants (Plantago major and Capsicum annuum) resulted hosting ‘Ca. P. asteris’ strains, and one cicadellid (Balclutha incisa) was carrying a ‘Ca. P. solani’ strain. A new pomegranate disease complex associated with multiple phytoplasmas, including ‘Ca. P. aurantifolia’ and ‘Ca. P. ulmi’, never reported before in this host plant, is described here. Moreover, preliminary indications are provided on its possible epidemiology in Jordan, involving two putative insect vectors (M. sexnotatus, B. incisa) first reported in the Country.     

Embryonic shell structure of Early–Middle Jurassic belemnites,and its significance for belemnite expansion and diversification in the Jurassic

Early Jurassic belemnites are of particular interest to the study of the evolution of skeletal morphology in Lower Carboniferous to the uppermost Cretaceous belemnoids, because they signal the beginning of a global Jurassic–Cretaceous expansion and diversification of belemnitids. We investigated potentially relevant, to this evolutionary pattern, shell features of Sinemurian–Bajocian Nannobelus, Parapassaloteuthis, Holcobelus and Pachybelemnopsis from the Paris Basin. Our analysis of morphological, ultrastructural and chemical traits of the earliest ontogenetic stages of the shell suggests that modified embryonic shell structure of Early–Middle Jurassic belemnites was a factor in their expansion and colonization of the pelagic zone and resulted in remarkable diversification of belemnites. Innovative traits of the embryonic shell of Sinemurian–Bajocian belemnites include: (1) an inorganic–organic primordial rostrum encapsulating the protoconch and the phragmocone, its non‐biomineralized component, possibly chitin, is herein detected for the first time; (2) an organic rich closing membrane which was under formation. It was yet perforated and possessed a foramen; and (3) an organic rich pro‐ostracum earlier documented in an embryonic shell of Pliensbachian Passaloteuthis. The inorganic–organic primordial rostrum tightly coating the protoconch and phragmocone supposedly enhanced protection, without increase in shell weight, of the Early Jurassic belemnites against explosion in deep‐water environment. This may have increased the depth and temperature ranges of hatching eggs, accelerated the adaptation of hatchlings to a nektonic mode of life and promoted increasing diversity of belemnoids. This study supports the hypothesis that belemnite hatchlings were ‘a miniature of the adults’.     

Das Verhalten einiger pilzlicher Antagonisten in der Rhizosphäre resistenter und anfälliger Gewächshaustomaten

Action of some fungal antagonists in the rhizosphere of resistant and susceptible tomato plants in the greenhouse The quantitative presence of the rhizospheric mycoflora fungi: Aspergillus alutaceus, Paecilomyces lilacinus, Penicillium herquei, P. nigricans and Trichoderma viride known for its antagonistic action to many pathogens is essentially differentiated in the two cultivars – the sensitive ‘Early pack’ and the resistant to tracheomycosis ‘GC 204′. It seems that the presence of the cultivar ‘GC 204’ favours the growth of these fungi. The first establishment of the fungi Penicillium chrysogenum and P. funiculosum, which are isolated from both cultivars, in the ‘Early pack’ rhizosphere might facilitate the colonization of this zone by the above mentioned antagonist which is not favoured by the sensitive cultivar. Such a changein the rhizospheric mycoflora of the sensitive cultivar may introduce some resistant to soil borne fungi diseases and open new perspectives of the biological control of these diseases.     

A variant in ANKK1 modulates acute subjective effects of cocaine: a preliminary study

This study aimed to evaluate whether functional variants in the ankyrin repeat and kinase domain‐containing 1 (ANKK1) gene and/or the dopamine receptor D2 (DRD2) gene modulate the subjective effects (reward or non‐reward response to a stimulus) produced by cocaine administration. Cocaine‐dependent participants (N = 47) were administered 40 mg of cocaine or placebo at time 0, and a subjective effects questionnaire (visual analog scale) was administered 15 min prior to cocaine administration, and at 5, 10, 15 and 20 min following administration. The influence of polymorphisms in the ANKK1 and DRD2 genes on subjective experience of cocaine in the laboratory was tested. Participants with a T allele of ANKK1 rs1800497 experienced greater subjective ‘high’ (P = 0.00006), ‘any drug effect’ (P = 0.0003) and ‘like’ (P = 0.0004) relative to the CC genotype group. Although the variant in the DRD2 gene was shown to be associated with subjective effects, linkage disequilibrium analysis revealed that this association was driven by the ANKK1 rs1800497 variant. A participant's ANKK1 genotype may identify individuals who are likely to experience greater positive subjective effects following cocaine exposure, including greater ‘high’ and ‘like’, and these individuals may have increased vulnerability to continue using cocaine or they may be at greater risk to relapse during periods of abstinence. However, these results are preliminary and replication is necessary to confirm these findings.     

Morphology, molecules, and character congruence in the phylogeny of South American geophagine cichlids (Perciformes, Labroidei)

Phylogenetic relationships among the Neotropical cichlid subfamily Geophaginae were examined using 136 morphological characters and a molecular dataset consisting of six mitochondrial and nuclear genes. Topologies produced by morphological and combined data under parsimony were contrasted, congruence among different partitions was analysed, and potential effects of character incongruence and patterns of geophagine evolution on phylogenetic resolution are discussed. Interaction of morphological and molecular characters in combined analysis produced better resolved and supported topologies than when either was analysed separately. Combined analyses recovered a strongly supported Geophaginae that was closely related to Cichlasomatinae. Within Geophaginae, two sister clades included all geophagine genera. Acarichthyini (Acarichthys+Guianacara) was sister to the ‘B clade’, which contained the ‘Geophagus clade’ (‘Geophagus’steindachneri+Geophagus sensu stricto, and both sister to Gymnogeophagus) as sister to the ‘Mikrogeophagus clade’ (Mikrogeophagus+‘Geophagus’brasiliensis), and in turn, the Geophagus and Mikrogeophagus clades were sister to the crenicarine clade (Crenicara+Dicrossus) and Biotodoma. The second geophagine clade included the ‘Satanoperca clade’ (Satanoperca+Apistogramma and Taeniacara) as sister to the ‘Crenicichla clade’ (Crenicichla+Biotoecus). Several lineages were supported by unique morphological synapomorphies: the Geophaginae + Cichlasomatinae (5 synapomorphies), Geophaginae (1), Crenicichla clade (3), crenicarine clade (1), the sister relationship of Apistogramma and Taeniacara (4) and of Geophagus sensu stricto and‘Geophagus’steindachneri (1), and the cichlasomine tribe Heroini (1). Incorporation of Crenicichla in Geophaginae reconciles formerly contradictory hypotheses based on morphological and molecular data, and makes the subfamily the most diverse and ecologically versatile clade of cichlids outside the African great lakes. Results of this study support the hypothesis that morphological differentiation of geophagine lineages occurred rapidly as part of an adaptive radiation.     

Late Famennian gastropoda from south-west England

The gastropod fauna of the Upper Devonian Baggy and Pilton formations in south‐west England is revised and includes some 30 taxa. The topmost part of the Upper Famennian succession in Devon is represented by clastic near‐shore and shallow shelf sediments, indicating a short‐term transgressive phase (‘Strunian Transgression’). The sequence yields a highly diverse fauna dominated by brachiopods and ostracodes, locally supplemented by crinoids, bryozoans, trilobites and molluscs. The taxa ‘Patellostium’britannicum sp. nov., Angyomphalus (Angyomphalus) junius sp. nov. and Dictyotomaria eurocapillaria sp. nov. are erected; a junior homonym is replaced by Macrochilina? piltonensis nom. nov. The gastropod fauna displays an independent character, where latest Devonian faunal elements overlap with Late Palaeozoic taxa expressing a transition similar to that of the bivalves, brachiopods, echinoderms and corals, without a sharp faunal break at the Devonian/Carboniferous boundary. Apart from the Caenogastropoda, all subclasses of gastropods are represented. Members of the bellerophontoids, pleurotomarioids and loxonematoids are most abundant, followed by murchisonioids, naticimorphs, euomphalomorphs and platyceratoids. The various gastropod groups represent different ecological demands and trophic categories, and together with the accompanying fauna indicate that nearly all habitats and niches were occupied in the shallow South Laurussian Shelf.     

Unisexual rock lizard might be outcompeting its bisexual progenitors in the Caucasus

We compared the distributions, abundances and ecological requirements of parthenogenetic lizard Darevskia ‘dahli’ and its bisexual progenitors, D. portschinskii and D. mixta, in Georgia. We developed a regression model relating the species abundances with the distribution of climates. Darevskia portschinskii lives in warmer and drier climates than D. mixta; D. ‘dahli’ has the intermediate requirements. Temperature is more important than humidity for D. portschinskii, humidity is more important for D. mixta and both temperature and humidity are important for D. ‘dahli’. Suitable habitats of all three species overlap broadly; however, the observed ranges partly overlap only for D. ‘dahli’ and D. portschinskii. The observed abundance of each species, related to its predicted abundance, is lower at the sites with potential competitors. Darevskia ‘dahli’ occupies a higher proportion of the suitable habitats and has higher abundances than the progenitor species. Competition with D. ‘dahli’ is an important factor determining current distribution pattern of D. portschinskii and D. mixta. The parthenogen is a stronger competitor than the bisexual breeders and potential advantages of the bisexual reproduction remain unrealized in the given temporal and spatial scale. To explain domination of bisexually breeding lizards on the global scale, considering climate changes in geological timescale is necessary. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 447–460.     

Theoretical Model of the Three-dimensional Structure of a Disease Resistance Gene Homolog Encoding Resistance Protein in Vigna mungo

Abstract

Plant disease resistance (R) genes, the key players of innate immunity system in plants encode ‘R’ proteins. ‘R’ protein recognizes product of avirulance gene from the pathogen and activate downstream signaling responses leading to disease resistance. No three dimensional (3D) structural information of any ‘R’ proteins is available as yet. We have reported a ‘R’ gene homolog, the 'VMYR1′, encoding ‘R’ protein in Vigna mungo. Here, we describe the homology modeling of the 'VMYR1′ protein. The model was created by using the 3D structure of an ATP-binding cassette transporter protein from Vibrio cholerae as a template. The strategy for homology modeling was based on the high structural conservation in the superfamily of P-loop containing nucleoside triphosphate hydrolase in which target and template proteins belong. This is the first report of theoretical model structure of any ‘R’ proteins.     

TaRPP13-3, a CC-NBS-LRR-like gene located on chr 7D,promotes disease resistance to wheat powdery mildew in Brock

Disease resistance (R) gene, RPP13, plays an important role in the resistance of plants to pathogen infections; its function in resistance of wheat to powdery mildew remains unknown. In this study, a RNA-Seq technique was used to monitor expression of genes in susceptible wheat ‘Jing411’ and resistant near-isogenic line ‘BJ-1’ in response to powdery mildew infection. Overall, 413 differential expression genes were observed and identified as involved in disease resistance. RPP13 homologous gene on wheat chromosome 7D was preliminarily identified using the wheat 660K SNP chip. RPP13 was highly expressed in ‘BJ-1’ and encodes 1,027 amino acids, including CC, NB and LRR domain, termed TaRPP13-3. After inoculation with powdery mildew, expression of TaRPP13-3 in resistant wheat changed with time, but average expression was higher when compared to susceptible variety, thus indicating that TaRPP13-3 is involved in resistance to powdery mildew. Virus-induced gene silencing (VIGS) was used to inhibit expression of TaRPP13-3 in resistant parent ‘Brock’. Results indicated that silencing of TaRPP13-3 led to decreased disease resistance in ‘Brock’. Overall results of this study indicate that TaRPP13-3 gene is involved in the defence response of wheat to powdery mildew and plays a positive role in wheat powdery mildew interactions.     

Evolution of mimicry in the New World Dysdercus (Hemiptera: Pyrrhocoridae)

Evolution of mimicry rings is reconstructed for the New World species of cotton-stainer bugs (Dysdercus, Hemiptera: Pyrrhocoridae). Using a cladistic analysis of 43 species (including D. silaceus Doesburg, 1968 stat. nov . and D. modestus Doesburg, 1968 stat. nov .), evolution of colour patterns and biogeographical history of the clade are hypothesized. Three probable mimicry rings are obtained from the analysis, together with data about their possible model–mimic or comimic–comimic structures: (a) ‘Yellow’ species in north-western South America and in the Andes (several possible models, D. rusticus, D. mimus part., D. imitator part., and D. collaris part. as mimics); (b) ‘Median Yellow–Black’ species with a median-forewing black pattern in north-western South America and Central America (several possible models, D. basialbus as a mimic); (c) ‘Median Red–Black’ species with a median-forewing black pattern in the Caribbean islands (D. andreae, D. discolor, D. neglectus–D. sanguinarius clade, and D. jamaicensis–D. fervidus–D. ocreatus clade as comimics). A few additional, less supported rings are also identified. Two highly polymorphic species (D. obscuratus, D. mimus) seem to enter different mimicry rings in different regions.