Mariner Elements Research Articles

Parasitism at the ecosystem level in the Baltic Sea.

The Baltic Sea is characterized by organisms that can tolerate brackish water. Because of the Sea's history during glacial times, its flora and fauna (and also their parasites) can be traced to marine, freshwater and genuine brackish elements beside glacial relics. Snails, planktonic copepods, benthic amphipods and isopods are important intermediate hosts of diverse helminths; in addition polychaetes, bivalves and fishes may also act as final hosts. The most important final hosts, beside fishes, were seals and birds; these were able to disperse the parasites over the whole of the Baltic. Decreasing salinity from west to east limits the distribution of many parasites. Several marine and genuine brackish water species have almost spread over the whole Baltic. Freshwater species, however, have a lower tolerance than marine species and are only rarely found in the western part. A serious problem in the Baltic is eutrophication which can lead to massive abundances of generalist parasites, in host populations as well as host individuals. The final stage of this influence can cause a general decrease of host abundance and, as a consequence, of all kinds of parasites, due to oxygen deficiency. In comparison with the species spectrum of other brackish waters in Europe, the Baltic presents some endemic parasites as well as sharing parasite species with the Mediterranean and even the Black Sea.

Characterization and molecular phylogenetic analysis of mariner elements from wild and domesticated species of silkmoths

Transposable elements are powerful tools for studying molecular genetics as they serve as agents for chromosomal insertions, deletions, or rearrangements and are found to be maintained in a variety of the genomes. The mariner like elements (MLEs), first isolated from Drosophila mauritiana (Haymer and Marsh, 1986; Jacobson et al., 1986), are now known to be present in a wide range of animal species (see review Hartl et al., 1997b), and plants (Feschotte and Wessler, 2002; Jarvik and Lark, 1998). MLEs are characterized by the presence of an ORF coding for a transposase of about 350 amino acids, short inverted terminal repeats at the ends, and a TA duplication at the insertion site (Lohe et al., 1996). The MLE transposase contains two highly conserved motifs WVPHEL and YSPDLAP separated by about 150 amino acid motifs, as well as a specific D,D(34)D signature motif (Doak et al., 1994; Robertson, 1993). The MLEs have been classified into several distinct subfamilies according to sequence similarities; elements from different subfamilies are typically 40–56% identical at the nucleotide level (Robertson and MacLeod, 1993). Gene transfer between species, a phenomenon known as horizontal gene transfer, appears to have played an important role in the evolution of MLEs. Horizontal transmission of MLEs is inferred from the occurrence of very similar transposon sequences in distantly related species, and from presence of different subfamilies of mariner elements in any particular species (Robertson, 1993). The extremely broad host range of MLEs, indicative of the host independence of the transposition process, has attracted interests because of the potential use of MLEs for genetic manipulations with insect species, with special emphasis on insects of economic importance (Kidwell, 1993). Recent studies demonstrated the potential of mariner-based transformation vectors for introducing exogenous DNA into the wide range of hosts, including fruitfly, mouse, chicken, mosquito, zebrafish, and leishmania (for recent review see Plasterk et al., 1999). MLEs also present important issues from an evolutionary point of view. The vast majority of MLEs are not functional, because they contain multiple inactivating mutations such as deletions, insertions, and nucleotide substitutions (Lohe et al., 1997; Maruyama et al., 1991; Robertson, 1993). The only mariner elements demonstrated to be autonomous are the MosI from D. mauritiana (Medhora et al., 1991) and closely related elements from Drosophila simulans (Capy et al., 1992). This apparent predominance of inactive MLEs prompted the presumption that mutational inactivation is an important part of the MLE life cycle within the species, which follows the initial invasion by horizontal transmission. These processes, along with the stochastic loss of inactive MLEs by random genetic drift, have been implicated as possible mechanisms underlying the curious distribution of MLEs among species (Lohe et al., 1995; Hartl et al., 1997a). To explore the evolutionary biology and dynamics of the MLEs, we undertook a study of MLEs in the genomes of diverse silkmoths collected from various parts of the world. The species used for mariner analysis included representatives of the domesticated silkmoth Bombyx mori (chromosome no. 28, mariner nomenclature, Bmmar), (Indian polyvoltine strain, Nistari) and its wild progenitor, Bombyx mandarina (27, Bmamar) and wild silkmoths of the Saturniidae family [Antheraea mylitta Molecular Phylogenetics and Evolution 25 (2002) 210–217 MOLECULAR PHYLOGENETICS AND EVOLUTION

What can be deduced from chemical measurement in an open-field raingauge? An example in the Maures Massif, southeastern France

The deposition of chemical elements in a catchment occurs through three different processes: wet, dry and cloud deposition. Total deposition cannot be inferred from measurements made with open-field raingauges, and still constitutes a challenge to scientific method. The chemical composition of samples from an open-field raingauge (bulk precipitation) was analysed over a period of several years in a small Mediterranean catchment in the Maures Massif, France. The input of chloride measured in this way was two times lower than the output, despite the fact that this element is reputed to be conservative, which means input and output should roughly balance. This implies that input has previously been underestimated. Analysis of the bulk precipitation data was carried out taking into account both the history of rain events and of sampling. This study allowed the relative parts of the different deposition processes to be quantified. Dry deposition can provide from 20% to more than 80% of the anthropogenic and terrigenic elements (Ca2+, Mg2+, K+, NO3 −, SO4 2-, SiO2) to the rain samples. The occult deposition of marine elements on the catchment area (50% of total deposition) was found to be mostly due to cloud deposition during wet periods.

Trace elements and major species in precipitation at African stations: concentrations and sources

Abstract The chemical composition of rainwaters is important in obtaining information on the aerosols and gaseous species present in the atmosphere. Original data on the concentrations of trace elements and major species in the dissolved and particulate fractions of rainwater samples collected in intertropical Africa were used to determine the potential sources of chemical species. The photographic and mineralogical characterization of rainwater particles using scanning electron microscopy allow to identify the various origins of aerosols and the associated chemical elements: (i) the crustal source characterized by clay minerals, kaolinite (Al, Si), illite (Al, Si and K) and Fe, Ti, and Mn oxides, (ii) vegetation relicts: Mg, Si, Cl, Mn and Zn have been identified in these biogenic particles and (iii) carbonaceous particles (mainly Si) emitted during vegetation fires. Ionic charge balance calculation for the stations located in the rain forest and wet savanna zones (Cameroon, Centrafrican Republic and Ivory Coast) exhibit an anion deficit from 20 to 50 % (between 7 and 9 μeq.l−1). Measured total organic carbon concentrations (between 0.5 and 3.3 mg.l−1), are much higher than acetic and formic acid. The presence of mimic and/or fulvic substances emitted from the vegetation can explain this anion deficit. The results obtained in this study confirm the existence of three important sources of atmospheric compounds in intertropical Africa: (i) the silicate upper crust source: Sc, Ti, Fe, Y, Zr, Nb, Cs, La, Ce, Nd, Yb, Th and U exhibit enrichment factors very close to 1, (ii) the biogenic and biomass burning source characterized by the following elements: Mg, Cl, K, Ca, Mn, Zn, Rb, Sr, and (iii) two minor sources; marine (Mg, Na, Cl) and anthropogenic (Cr, Co, Zn, Ba and Pb). For the stations located in the rain forest zone, all these sources appear strongly linked. High correlations are observed between elements of various origins. This suggest a strong interaction between terrigenous, biogenic, marine and anthropogenic aerosols. The deposition of aerosols onto vegetation and the re-mobilization of the chemical species through natural emissions or biomass burning could explain these correlations and the observed chemical fractionation of marine origin elements such as Cl and Na.

Palynofacies of marginal marine deposits: the rhaetian of the east margin of the Massif Central (France)

The methodology presented concerns the definition of palynofacies. It develops 3 procedure stages based on multivariate analyses: 1 — define the palynomaceral facies, 2 — define and compare palynomorph facies with palynomaceral facies and 3 — exploit the two precedent categories of facies. The study deals with Rhaetian sedimentary cycles corresponding to the western limit boundary of the southeastern France intracratonic basin. Rhaetian strata are representative of paralic depositional environments, overlying Triassic fluvial deposits. On the palynomaceral sequence, that is revealed by multivariate analyses, the most buoyant particles are the needle-like phytoclasts. Crevasse splays, dewatering, drowned soils and restricted wave-influenced deposit facies yield them. The less buoyant particles are the black massive or polygonal phytoclasts. They were produced by crevasses, deltaic shales, distributary channels, palaeosoils, sheet-floods, shoals and shoreface facies. The bisaccate pollen Ovalipollis and the nonsaccate pollen Circumpolles are associated with needle-like particles. They are linked to deltaic shales, restricted deposits sheet-floods, shoal, shoreface and storm facies. The marine element Dapcodinium is not related to a particular palynomaceral type but could be compared to the lowest buoyant phytoclast. Deltaic plain and back-shoal lagoonal facies favour the concentration of Dapcodinium. The distribution of the small size dinoflagellate cysts ( Dapcodinium) and large size dinoflagellate cysts ( Rhaetogonyaulax) emphasizes the role of the size in the floatation competence. Base level-rises and highs are marked by amalgamated bioclastic deposits, fluvial channel fills, mixed siliciclastic-bioclastic amalgamated shoals, storm deposits or ravinement surfaces. Needle-like particles, Ovalipollis and Circumpolles are associated to these deposits. Base level-falls are represented by crevasse splay deposits, fluvial stream incisions, non-incising fluvial channels, sheet flood and stacked palaeosol facies. Black roundish or equidimensional translucent phytoclasts, Rhaetogonyaulax, short-spine Micrhystridium (acritarch) and smooth-walled spores are associated with these facies. In addition to to the energy factor, the water depth constrains both phytoclast and palynomorph sedimentation.

Unexpected stability of mariner transgenes in Drosophila.

A number of mariner transformation vectors based on the mauritiana subfamily of transposable elements were introduced into the genome of Drosophila melanogaster and examined for their ability to be mobilized by the mariner transposase. Simple insertion vectors were constructed from single mariner elements into which exogenous DNA ranging in size from 1.3 to 4.5 kb had been inserted; composite vectors were constructed with partial or complete duplications of mariner flanking the exogenous DNA. All of the simple insertion vectors showed levels of somatic and germline excision that were at least 100-fold lower than the baseline level of uninterrupted mariner elements. Although composite vectors with inverted duplications were unable to be mobilized at detectable frequencies, vectors with large direct duplications of mariner could be mobilized. A vector consisting of two virtually complete elements flanking exogenous DNA yielded a frequency of somatic eye-color mosaicism of approximately 10% and a frequency of germline excision of 0.04%. These values are far smaller than those observed for uninterrupted elements. The results imply that efficient mobilization of mariner in vivo requires the presence and proper spacing of sequences internal to the element as well as the inverted repeats.

Ultrashort fairings for suppressing vortex-induced-vibration

An ultrashort fairing is disclosed for suppressing vortex-induced vibration in substantially cylindrical marine elements. The ultrashort falling has a leading edge substantially defined by the circular profile of the marine element for a distance following at least about 270 degrees thereabout and a pair of shaped sides departing from the circular profile of the marine riser and converging at a trailing edge. The ultrashort fairing has dimensions of thickness and chord length such that the chord to thickness ratio is between about 1.20 and 1.10.

Polymorphisms flanking the mariner integration sites in the rice gall midge (Orseolia oryzae Wood-Mason) genome are biotype-specific.

In an effort to study genome diversity within and between the Indian biotypes of the Asian rice gall midge, Orseolia oryzae, a major insect pest of rice, we made use of mariner transposable element integration site polymorphisms. Using degenerate primers, the design of which is based on mariner sequences, we amplified a ca. 450 bp mariner sequence from the rice gall midge. The mariner sequence showed homology with that of a mariner element isolated from the Hessian fly, Mayetiola destructor, a major dipteran pest of wheat. Southern hybridization, using this mariner fragment as a probe, revealed that the mariner elements are moderately to highly repetitive in the rice gall midge genome. Based on the sequence information of this 450-bp PCR-amplified fragment, outward-directed primers were designed and used in an inverse PCR (iPCR) to amplify the DNA flanking the conserved regions. To study the regions flanking the mariner integration sites, we employed a novel PCR-based approach: a combination of sequence specific amplification polymorphism (SSAP) and amplified fragment length polymorphism (AFLP). The outward-directed mariner-specific primer was used in combination with adapter-specific primers with 1-3 selective nucleotides at their 3' ends. The amplification products were resolved on an agarose gel, Southern-transferred onto nylon membranes, and probed with the iPCR fragment. Results revealed biotype-specific polymorphisms in the regions flanking the mariner integration sites, suggesting that mariner elements in the rice gall midge may be fixed in a biotype-specific manner. The implications of these results are discussed in the context of biotype differentiation.

A new basal subfamily of mariner elements in Ceratitis rosa and other tephritid flies.

Several copies of highly related transposable elements, Crmar2, Almar1, and Asmar1, are described from the genomes of Ceratitis rosa, Anastrepha ludens, and A. suspensa, respectively. One copy from C. rosa, Crmar2.5, contains a full-length, uninterrupted ORF. All the other copies, from the three species contain a long deletion within the putative ORF. The consensus Crmar2 element has features typical of the mariner/Tc1 superfamily of transposable elements. In particular, the Crmar2 consensus encodes a D,D41D motif, a variant of the D,D34D catalytic domain of mariner elements. Phylogenetic analysis of the relationships of these three elements and other members of the mariner/Tc1 superfamily, based on their encoded amino acid sequences, suggests that they form a new basal subfamily of mariner elements, the rosa subfamily. BLAST analyses identified sequences from other diptera, including Drosophila melanogaster, which appear to be members of the rosa subfamily of mariner elements. Analyses of their molecular evolution suggests that Crmar2 entered the genome of C. rosa in the recent past, a consequence of horizontal transfer.

Mobilization of a Drosophila transposon in the Caenorhabditis elegans germ line.

Transposons have been enormously useful for genetic analysis in both Drosophila and bacteria. Mutagenic insertions constitute molecular tags that are used to rapidly clone the mutated gene. Such techniques would be especially advantageous in the nematode Caenorhabditis elegans, as the entire sequence of the genome has been determined. Several different types of endogenous transposons are present in C. elegans, and these can be mobilized in mutator strains (reviewed in ref. 1). Unfortunately, use of these native transposons for regulated transposition in C. elegans is limited. First, all strains contain multiple copies of these transposons and thus new insertions do not provide unique tags. Second, mutator strains tend to activate the transposition of several classes of transposons, so that the type of transposon associated with a particular mutation is not known. Here we demonstrate that the Drosophila mariner element Mos1 can be mobilized in C. elegans. First, efficient mobilization of Mos1 is possible in somatic cells. Second, heritable insertions of the transposon can be generated in the germ line. Third, genes that have been mutated by insertion can be rapidly identified using inverse polymerase chain reaction. Fourth, these insertions can subsequently be remobilized to generate deletion and frameshift mutations by imperfect excision.

Mars Learning: The Marine Corps' Development of Small Wars Doctrine, 1915-1940

Keith B. Bickel challenges a host of military and strategic theories that treat particular bureaucratic structures, large organizations, and elites as the progenitors of doctrine. This timely study of how the military draws lessons from interventions focuses on the overlooked role that mid-level combat officers play in creating military doctrine. Mars Learning closely evaluates Marine civil and military pacification operations in Haiti, the Dominican Republic, and Nicaragua, and illuminates the debates surrounding the development of Marine Corps' small wars doctrine between 1915 and 1940. The result is compelling evidence of how field experience obtained before 1940 played a role in shaping the Marine Corps' Small Wars Manual and elements of doctrine that exist today. How the Marines organized lessons at that time provides important insights into how doctrine is likely to be generated today in response to post-Cold War interventions around the globe.

Loss of transposase-DNA interaction may underlie the divergence of mariner family transposable elements and the ability of more than one mariner to occupy the same genome.

Mariners are a large family of eukaryotic DNA-mediated transposable elements that move via a cut-and-paste mechanism. Several features of the evolutionary history of mariners are unusual. First, they appear to undergo horizontal transfer commonly between species on an evolutionary timescale. They can do this because they are able to transpose using only their own self-encoded transposase and not host-specific factors. One consequence of this phenomenon is that more than one kind of mariner can be present in the same genome. We hypothesized that two mariners occupying the same genome would not interact. We tested the limits of mariner interactions using an in vitro transposition system, purified mariner transposases, and DNAse I footprinting. Only mariner elements that were very closely related to each other (ca. 84% identity) cross-mobilized, and then inefficiently. Because of the dramatic suppression of transposition between closely related elements, we propose that to isolate elements functionally, only minor changes might be necessary between elements, in both inverted terminal repeat and amino acid sequence. We further propose a mechanism to explain mariner diversification based on this phenomenon.

The wild-type conformation of the Mos-1 inverted terminal repeats is suboptimal for transposition in bacteria.

The two inverted terminal repeats (ITRs) flanking the Mos-1 mariner element differ in sequence at four positions. Gel retardation experiments indicated that each of these differences has a significant impact on the quality of the interaction between the ITR and the Mos-1 transposase. We showed that the transposase binds to the 3' ITR better than to the 5' ITR. The results of transposition assays performed in Escherichia coli indicated that these differences have an influence on the rate of transposition and the stability of the transposition products. Finally, we find that the wild-type configuration of the Mos-1 element, with one 5' ITR and one 3' ITR, is less efficient for transposition in bacteria than that of an element having two 3' ITRs.

High-Resolution Architecture and Paleoecology of an Active Margin, Storm-Flood Influenced Estuary, Quinault Formation (Pliocene), Washington

Other| December 01, 2000 High-Resolution Architecture and Paleoecology of an Active Margin, Storm-Flood Influenced Estuary, Quinault Formation (Pliocene), Washington KATHLEEN A. CAMPBELL; KATHLEEN A. CAMPBELL 1Department of Geology, University of Auckland, Private Bag 92019, Auckland, New Zealand Search for other works by this author on: GSW Google Scholar ELIZABETH A. NESBITT ELIZABETH A. NESBITT 2Department of Geological Sciences and Burke Museum of Natural History and Culture, Box 353010, University of Washington, Seattle, WA 98195-3010 Search for other works by this author on: GSW Google Scholar PALAIOS (2000) 15 (6): 553–579. https://doi.org/10.1669/0883-1351(2000)015<0553:HRAAPO>2.0.CO;2 Article history accepted: 08 Aug 2000 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation KATHLEEN A. CAMPBELL, ELIZABETH A. NESBITT; High-Resolution Architecture and Paleoecology of an Active Margin, Storm-Flood Influenced Estuary, Quinault Formation (Pliocene), Washington. PALAIOS 2000;; 15 (6): 553–579. doi: https://doi.org/10.1669/0883-1351(2000)015<0553:HRAAPO>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyPALAIOS Search Advanced Search Abstract An exhumed Pliocene estuarine sequence is preserved in exquisite detail in the Quinault Formation of coastal western Washington. The thick fill of the Quinault estuarine basin (∼700 m) represents a single transgressive-regressive system that was punctuated by subduction-related tectonic events, and may reflect erosion and sediment accumulation during accelerated uplift of the Olympic Mountains in the Pliocene. Sedimentation patterns in the ancient Quinault estuary were influenced strongly both by floods on the paleo-Quinault River, and by storm waves on the high-energy, open Pacific coast. Body fossils were derived from both marine and brackish faunal elements. Trace fossil suites indicate that the benthos flourished in the fluctuating physicochemical conditions of an estuary in dynamic equilibrium. An estuarine-specific trace fossil, a new ichnospecies of Psilonichnus that is attributed to burrows of the mud shrimp Upogebia pugettensis, is restricted to inlet-mouth, muddy sandstone facies. The marine-marginal marine transition is well-preserved in Quinault estuarine strata (exposed in the Point Grenville and Cape Elizabeth areas), as evidenced by: (1) distinctive sedimentologic signatures characteristic of lower shoreface, estuarine mouth, central basin, tidal creek/flat, and fluvial subenvironments; and, (2) systematic changes in trace fossil associations in the up-estuary direction, from Skolithos ichnofacies elements to a mixed Skolithos-Cruziana assemblage to Glossifungites associations with rhizome phytoburbation. Hence, Quinault strata record a classic tripartite division of an ancient estuarine system, allowing a fine-scale delineation of subenvironments in an active tectonic regime. You do not currently have access to this article.

Sleeping Beauty, a wide host-range transposon vector for genetic transformation in vertebrates

Sleeping Beauty (SB), a member of the Tc1/mariner superfamily of transposable elements, is the only active DNA-based transposon system of vertebrate origin that is available for experimental manipulation. We have been using the SB element as a research tool to investigate some of the cis and trans-requirements of element mobilization, and mechanisms that regulate transposition in vertebrate species. In contrast to mariner transposons, which are regulated by overexpression inhibition, the frequency of SB transposition was found to be roughly proportional to the amount of transposase present in cells. Unlike Tc1 and mariner elements, SB contains two binding sites within each of its terminal inverted repeats, and we found that the presence of both of these sites is a strict requirement for mobilization. In addition to the size of the transposon itself, the length as well as sequence of the DNA outside the transposon have significant effects on transposition. As a general rule, the closer the transposon ends are, the more efficient transposition is from a donor molecule. We have found that SB can transform a wide range of vertebrate cells from fish to human. However, the efficiency and precision of transposition varied significantly among cell lines, suggesting potential involvement of host factors in SB transposition. A positive-negative selection assay was devised to enrich populations of cells harboring inserted transposons in their chromosomes. Using this assay, of the order of 10,000 independent transposon insertions can be generated in human cells in a single transfection experiment. Sleeping Beauty can be a powerful alternative to other vectors that are currently used for the production of transgenic animals and for human gene therapy.

In vivo transposon mutagenesis of the methanogenic archaeon Methanosarcina acetivorans C2A using a modified version of the insect mariner-family transposable element Himar1.

We present here a method for in vivo transposon mutagenesis of a methanogenic archaeon, Methanosarcina acetivorans C2A, which because of its independence from host-specific factors may have broad application among many microorganisms. Because there are no known Methanosarcina transposons we modified the mariner transposable element Himar1, originally found in the insect Hematobia irritans, to allow its use in this organism. This element was chosen because, like other mariner elements, its transposition is independent of host factors, requiring only its cognate transposase. Modified mini-Himar1 elements were constructed that carry selectable markers that are functional in Methanosarcina species and that express the Himar1 transposase from known Methanosarcina promoters. These mini-mariner elements transpose at high frequency in M. acetivorans to random sites in the genome. The presence of an Escherichia coli selectable marker and plasmid origin of replication within the mini-mariner elements allows facile cloning of these transposon insertions to identify the mutated gene. In preliminary experiments, we have isolated numerous mini-mariner-induced M. acetivorans mutants, including ones with insertions that confer resistance to toxic analogs and in genes that encode proteins involved in heat shock, nitrogen fixation, and cell-wall structures.

Triassic pelagic deposits of Timor: palaeogeographic and sea-level implications

In West Timor, Triassic deposits are found in the Parautochthonous Complex, as well as in the Allochthonous series of Sonnebait. A detailed biostratigraphic investigation, integrating field observations and facies analysis, allowed the reconstruction of a synthetic lithostratigraphic succession for the Upper Triassic; a stratigraphic transition from Carnian shales to Upper Norian–Rhaetian limestones is also shown by this study. The fossil content predominantly originates from an open marine environment; lithostratigraphic Units A–E are dated on the basis of radiolaria and palynomorphs, and Unit H, on ammonites and conodonts. The presence of pelagic bioclasts, together with normal grading, horizontal laminations, and current ripples, is indicative of a distal slope to basin environment. The ammonite rich condensed limestone of Unit H was deposited on a ‘pelagic carbonate plateau’ exposed to storms and currents. The organic facies have been used as criteria for biostratigraphy, palaeoenvironmental interpretation, and sequence stratigraphy. The palaeontological analysis of the Triassic succession of West Timor is based on the investigation of radiolaria and palynomorphs, in the marls and limestones of Units A–E, and also on ammonites and conodonts in the condensed limestone of Unit H. Units A and B are Carnian (Cordevolian) in age, based on the occurrence of the palynomorph Camerosporites secatus, associated with ‘ Lueckisporites’ cf. singhii, Vallasporites ignacii, Patinosporites densus and Partitisporites novimundanus. Unit C is considered as Norian, on the basis of a relatively high percentage of Gliscopollis meyeriana and Granuloperculatipollis rudis. Unit D contains significant palynomorphs and radiolaria; the organic facies, characterized by marine elements, is dominated by the Norian dinocysts Heibergella salebrosacea and Heibergella aculeata; the radiolaria confirm the Norian age. They range from the lowermost Norian to the lower Upper Norian. Unit E also contains radiolaria, associated in the upper part with the well-known marker of the Upper Norian, Monotis salinaria. For Unit E, the radiolaria attest to a Lower to Upper Norian age based on the occurrence of Capnodoce and abundant Capnuchosphaera; the upper part is Upper Norian to Rhaetian based on the presence of Livarella valida. Finally, the blocks of condensed limestone with ammonites and conodonts of Unit H allowed the reconstruction of a synthetic stratigraphic succession of Upper Carnian to Upper Norian age. Our stratigraphic data lead to the suggestion that the Allochthonous complex, classically interpreted as a tectonic melange of the accretionary prism of the Island Arc of Banda, is a tectonically dismembered part of a Triassic lithostratigraphic succession.

Mariner (Mos1) transposase and genomic integration of foreign gene sequences in Bombyx mori cells.

Widespread occurrence in insects and the capacity to transpose in the absence of host-derived factors means that mariner-like elements are considered to be attractive candidates for the development of a universal insect genetic transformation system. Here we show that the Mos1 mariner element of Drosophila mauritiana is capable of mediating excision and transposition events in a silkmoth (Bombyx mori) derived tissue culture cell line (Bm5 cells). Plasmid rescue assays, in combination with Southern hybridization and polymerase chain reaction (PCR) analyses, confirm that the Mos1 transposase can mediate excision of DNA sequences, inserted between terminally repeated sequences recognized by the transposase, and integration into the chromosomal DNA of the Bm5 cells. In addition to chromosomal integration events, inter- and intraplasmid transposition and target element excision events were also detected. Approximately 50% of the plasmids recovered from plasmid rescue assays were found to contain the 'signature' of Mos1-specific excision and/or integration events, indicating that the mariner transposase functions efficiently in the Bombyx cells. Because mariner-induced excision and integration events are strictly dependent on the presence of a co-transfected Mos1 transposase expression vector, it is clear that the multiple copies of endogenous mariner-like elements (Bmmar1) that exist in the Bombyx genome are neither functional nor do they interfere with the efficiency of the transposition process. Thus, the Mos1 element and, probably, mariner elements, in general, hold great promise for the development of genetic transformation systems for lepidopteran insects.

Evolution of different subfamilies of mariner elements within the medfly genome inferred from abundance and chromosomal distribution.

The abundance and distribution pattern of eight mariner elements from three different subfamilies in the genome of the medfly Ceratitis capitata were determined. The copy numbers, as determined by slot-blot analysis, were very different for these elements. Their abundance did not change significantly within the native, the ancient or the newly derived populations, indicating that the rapid colonization process of the medfly had not affected the copy number of mariner elements. The distribution of the mariner elements was analyzed using fluorescent in situ hybridization (FISH) with charge-coupled device (CCD) camera analysis. The pattern of distribution in euchromatin and heterochromatin varied greatly and was distinctive and specific for each element. The implications of these findings are discussed and it is concluded that they generally support the hypothesis of a transposition/selection model in which the abundance and distribution patterns of these elements are regulated primarily by selection against deleterious effects due to meiotic ectopic recombination, while genetic drift would have played a minor role.

The concentration, trend and seasonal variation of metals in the atmosphere in 16 Japanese cities shown by the results of National Air Surveillance Network (NASN) from 1974 to 1996

In this study, the data from National Air Surveillance Network (NASN) for selected crustal elements (Al, Ca, Fe, Mn, Sc and Ti), anthropogenic elements (As, Cu, Cr, Ni, Pb, V and Zn) and a marine element (Na) in atmospheric particulate matter have been evaluated over Japan from 1974 to 1996. The NASN had 16 sampling stations, Nopporo, Sapporo, Nonotake, Sendai, Niigata, Tokyo, Kawasaki, Nagoya, Kyoto-Hachiman, Osaka, Amagasaki, Kurashiki, Matsue, Ube, Chikugo-Ogori and Ohmuta in Japan, at which aerosols were regularly collected every month and samples collected by low volume air sampler were analyzed by neutron activation analysis (NAA) and X-ray fluorescence (XRF). Results of trend analysis showed that the annual average concentrations of crustal and anthropogenic elements decreased significantly between 1974 and 1996. Furthermore, the concentrations of selected crustal and anthropogenic elements were higher between 1974 and 1979 than between 1980 and 1989. Crustal elements displayed high concentrations in the “Kosa” period (the dust season from March to May) and in winter (November and December) and low concentrations in summer (July and August). The ratios of elemental average concentrations in the Kosa period to those of summer were 2–5 times higher and those of winter relative to those of summer were 1.5–3 times higher for crustally derived elements. Particularly, concentration of Sc in Matsue was 8 times higher during the Kosa period than during summer time. Some of anthropogenic elements also showed high concentrations in the Kosa Season and low concentrations in summer. The ratios of elemental concentration in the Kosa period to those of summer and those of winter relative to summer were 2–4 times higher for some anthropogenically derived elements. Especially, the concentration of Zn in Chikugo-Ogori was 5.7 times higher during wintertime than during summertime.