Beetles (Insecta,Coleoptera) in the arctic fauna: Communication 1. Faunal composition

Coleoptera, the largest insect order, appears to be subordinate to Diptera in the extent of colonization of the Arctic environment. Beetles comprise about 13% of the insect fauna of the tundra zone, yet in the high latitudes several of their families retain considerable levels of species diversity and play significant cenotic roles. The present communication reviews the circumpolar beetle fauna of the Arctic. Based on original data, literature sources and museum collections, with the use of extrapolations and analogies, the taxonomic and ecological diversity patterns of the suborders, series and families of Coleoptera are distinguished, the latitude-zonal distribution and the northernmost range limits of the species are analyzed, and their adaptations and cenotic relations are characterized.     

Superoxide dismutase in liver ischemia

The properties of Cu,Zn-superoxide dismutase (SOD) from rat liver after 2-hour total ischemia or after ischemia with subsequent 24-hour reperfusion were studied. Two hours after ischemia the specific activity of SOD decreases drastically (about 3-fold) - from 510 +/- 11 u./mg in normal tissue and 196 +/- 33 u./mg after ischemia showing a further increase after reperfusion (276 +/- 40 u./mg). Using competitive immunoenzymatic analysis, the relative contents of SOD in the cytosol were determined. After ischemia the SOD content in the cytosolic fraction decreased (approximately 3-fold) but returned to the initial level after reperfusion. Polyacrylamide gel electrophoresis revealed that in control samples active SOD is heterogeneous and produces 3-4 bands, similar to the purified SOD from rat liver. After the ischemia the intensity of minor fast band IV increased and a new band V of a still higher mobility appeared. After the reperfusion the electrophoretic patterns were similar to control. Two or three times more SOD antigen from ischemia liver cytosol was absorbed to the surface of polystyrol plate in a direct sorption enzyme immunoassay procedure as compared to that from intact liver cytosol. It is suggested that the decreases of amount and the activity as well as changes of properties of SOD could be due to its oxidative modification and degradation of the modified enzyme.     

Functional curation of the Sulfolobus solfataricus P2 and S. acidocaldarius 98-3 complete genome sequences

The thermoacidophiles Sulfolobus solfataricus P2 and S. acidocaldarius 98-3 are considered key model organisms representing a major phylum of the Crenarchaeota. Because maintaining current, accurate genome information is indispensable for modern biology, we have updated gene function annotation using the arCOGs database, plus other available functional, structural and phylogenetic information. The goal of this initiative is continuous improvement of genome annotation with the support of the Sulfolobus research community.     

Antibody responses against xenotropic murine leukemia virus-related virus envelope in a murine model

Background

Xenotropic murine leukemia virus-related virus (XMRV) was recently discovered to be the first human gammaretrovirus that is associated with chronic fatigue syndrome and prostate cancer (PC). Although a mechanism for XMRV carcinogenesis is yet to be established, this virus belongs to the family of gammaretroviruses well known for their ability to induce cancer in the infected hosts. Since its original identification XMRV has been detected in several independent investigations; however, at this time significant controversy remains regarding reports of XMRV detection/prevalence in other cohorts and cell type/tissue distribution. The potential risk of human infection, coupled with the lack of knowledge about the basic biology of XMRV, warrants further research, including investigation of adaptive immune responses. To study immunogenicity in vivo, we vaccinated mice with a combination of recombinant vectors expressing codon-optimized sequences of XMRV gag and env genes and virus-like particles (VLP) that had the size and morphology of live infectious XMRV.

Results

Immunization elicited Env-specific binding and neutralizing antibodies (NAb) against XMRV in mice. The peak titers for ELISA-binding antibodies and NAb were 1∶1024 and 1∶464, respectively; however, high ELISA-binding and NAb titers were not sustained and persisted for less than three weeks after immunizations.

Conclusions

Vaccine-induced XMRV Env antibody titers were transiently high, but their duration was short. The relatively rapid diminution in antibody levels may in part explain the differing prevalences reported for XMRV in various prostate cancer and chronic fatigue syndrome cohorts. The low level of immunogenicity observed in the present study may be characteristic of a natural XMRV infection in humans.     

Lepidoptera (Insecta) of polar deserts

Four species of Lepidoptera were found on Bolshevik Island, the Severnaya Zemlya Archipelago (the Middle-Siberian Arctic sector). The noctuid Xestia aequaeva (Benjamin, 1934) and the geometrid Psychophora cinderella Viidalepp, 2001 are considered residents, while the pickleworm Gesneria centuriella (Denis et Schiffermüller, 1775) and the plutellid Plutella xylostella (Linnaeus, 1758) were brought to the island by air currents. The records of Xestia aequaeva (78°37′N) and Psychophora cinderella (78°56′N) on Severnaya Zemlya are the northernmost for the families Noctuidae and Geometridae in the entire Palaearctic. The European, Middle-Siberian, and Beringian sectors of the Arctic appear to support two sympatric species of the genus Psychophora. The “last” lepidopterans along the heat gradient in the Northern Hemisphere are Psychophora spp. (including P. cinderella) and Gynaephora groenlandica (Wöcke, 1874). Both may serve as indicators in analysis of long-term climate changes in the Far North. The most important adaptations of Lepidoptera, as well as of other arthropod groups, to inhabiting the polar deserts are polyphagy and the capacity for perennial development, with female flight reduced or absent.     

Gamasid mites (Parasitiformes, Mesostigmata) of the European arctic and their distribution patterns

Analysis has been completed of all the available material on gamasid mites from insular and continental territories of the Barents Sea region. A total of 116 species has been revealed, including 9 new to science. The species Gamasus armatus L. Koch, 1879 is transferred to the genus Gamasodes Oudemans, 1939, thus becoming Gamasodes armatus (L. Koch, 1879), comb. n. Six species of gamasid mites occur even at the thermal limit in the Northern Hemisphere, on the ice-free grounds of Franz Josef Land (with mid-July temperatures ranging from ?1.2°C to +1.6°C). On Svalbard, 25 species have been recorded, as compared to 27 on Novaya Zemlya, 39 on Vaigach Island, 43 on Kolguev Island, 50 in the Pechora Bay, 37 on Kanin Peninsula, and 58 on the Eastern Murman coast. Despite the differences in the quality and quantity of material obtained during 30 years from numerous collectors, a relation between species diversity and summer heat supply has been revealed (linear regression coefficient: 0.816; significance level: 99%). The most diverse families are Ascidae (23 species, including 20 species of Arctoseius), Parasitidae (15, including 6 species of Vulgarogamasus), and Zerconidae (14, including 11 species of Zercon). The species Zercon michaeli Hala?kova, 1977, Zercon solenites Haarløv, 1942, Parasitellus papei (Karg, 1985), Parasitellus arcticus (Karg, 1985), and Halolaelaps gerlachi Hirschmann, 1966 have been recorded in Russia for the first time. The species Zercon acanticus Blaszak, 1978, Poecilochirus nordi Davydova, 1971, Euryparasitus tori Davydova, 1970, Gamasellus tundriensis Davydova, 1982, Arctoseius nikolskyi Makarova et Petrova, 1992, and Neoseiulus ellesmerei (Chant et Hansell, 1971) are new to the European list. The specific gamasid mites associated with lemmings or bumble-bees are absent on Franz Josef Land and Svalbard, since both archipelagoes were almost completely glaciated in the Late Pleistocene. An obviously temporary population of a member of the family Macrochelidae, namely, of the dung-compost cosmopolitan species Macrocheles muscaedomesticae (Scopoli, 1772) was first recorded in the High Arctic (Spitsbergen). Distribution ranges of many species, mainly of those of the genus Arctoseius, lie within the Metaarctic (sensu Yurtsev, 1977). High Arctic patterns have been confirmed for Arctoseius tschernovi Makarova, 2000, A. babenkoi Makarova, 2000, A. productus Makarova, 2000, Neoseiulus sp. aff. tibielingmiut (Chant et Hansell, 1971). However, quite a few of the species traditionally considered as “arctic” and inhabiting mainly arctic landscapes in North America and the western Palaearctic, have also been found in the Siberian mountains as far southwards as the Altai-Sayan mountain system: Antennoseius oudemansi (Thor, 1930), Proctolaelaps parvanalis (Thor, 1930), Zerconopsis labradorensis Evans et Hyatt, 1960, Zercon michaeli, Zercon solenites, etc. Similar arcto-montane patterns have also been revealed for some “mountain” species: Trachytes hirschmanni Hutu, 1973, Syskenozercon kosiri Athias-Henriot, 1976, Veigaia belovae Davydova, 1979, Iphidinychus gaieri (Schweizer, 1961), and Zercon spp. As the climate becomes milder, the total share of arctic and arcto-montane species in the individual regions of the European Arctic gradually drops from 100% (Franz Josef Land) to 12% (Eastern Murman coast).     

Archaeology of Eukaryotic DNA Replication

Recent advances in the characterization of the archaeal DNA replication system together with comparative genomic analysis have led to the identification of several previously uncharacterized archaeal proteins involved in replication and currently reveal a nearly complete correspondence between the components of the archaeal and eukaryotic replication machineries. It can be inferred that the archaeal ancestor of eukaryotes and even the last common ancestor of all extant archaea possessed replication machineries that were comparable in complexity to the eukaryotic replication system. The eukaryotic replication system encompasses multiple paralogs of ancestral components such that heteromeric complexes in eukaryotes replace archaeal homomeric complexes, apparently along with subfunctionalization of the eukaryotic complex subunits. In the archaea, parallel, lineage-specific duplications of many genes encoding replication machinery components are detectable as well; most of these archaeal paralogs remain to be functionally characterized. The archaeal replication system shows remarkable plasticity whereby even some essential components such as DNA polymerase and single-stranded DNA-binding protein are displaced by unrelated proteins with analogous activities in some lineages.Double-stranded DNA is the molecule that carries genetic information in all cellular life-forms; thus, replication of this genetic material is a fundamental physiological process that requires high accuracy and efficiency (Kornberg and Baker 2005). The general mechanism and principles of DNA replication are common in all three domains of life—archaea, bacteria, and eukaryotes—and include recognition of defined origins, melting DNA with the aid of dedicated helicases, RNA priming by the dedicated primase, recruitment of DNA polymerases and processivity factors, replication fork formation, and simultaneous replication of leading and lagging strands, the latter via Okazaki fragments (Kornberg and Baker 2005; Barry and Bell 2006; Hamdan and Richardson 2009; Hamdan and van Oijen 2010). Thus, it was a major surprise when it became clear that the protein machineries responsible for this complex process are drastically different, especially in bacteria compared with archaea and eukarya. The core components of the bacterial replication systems, such as DNA polymerase, primase, and replication helicase, are unrelated or only distantly related to their counterparts in the archaeal/eukaryotic replication apparatus (Edgell 1997; Leipe et al. 1999).The existence of two distinct molecular machines for genome replication has raised obvious questions on the nature of the replication system in the last universal common ancestor (LUCA) of all extant cellular life-forms, and three groups of hypotheses have been proposed (Leipe et al. 1999; Forterre 2002; Koonin 2005, 2006, 2009; Glansdorff 2008; McGeoch and Bell 2008): (1) The replication systems in Bacteria and in the archaeo–eukaryotic lineage originated independently from an RNA-genome LUCA or from a noncellular ancestral state that encompassed a mix of genetic elements with diverse replication strategies and molecular machineries. (2) The LUCA was a typical cellular life-form that possessed either the archaeal or the bacterial replication apparatus in which several key components have been replaced in the other major cellular lineage. (3) The LUCA was a complex cellular life-form that possessed both replication systems, so that the differentiation of the bacterial and the archaeo–eukaryotic replication machineries occurred as a result of genome streamlining in both lines of descent that was accompanied by differential loss of components. With regard to the possible substitution of replication systems, a plausible mechanism could be replicon takeover (Forterre 2006; McGeoch and Bell 2008). Under the replicon takeover hypothesis, mobile elements introduce into cells a new replication system or its components, which can displace the original replication system through one or several instances of integration of the given element into the host genome accompanied by inactivation of the host replication genes and/or origins of replication. This scenario is compatible with the experimental results showing that DNA replication DNA in Escherichia coli with an inactivated DnaAgene or origin of replication can be rescued by the replication apparatus of R1 or F1 plasmids integrated into the bacterial chromosome (Bernander et al. 1991; Koppes 1992). Furthermore, genome analysis suggests frequent replicon fusion in archaea and bacteria (McGeoch and Bell 2008); in particular, such events are implied by the observation that in archaeal genomes, genes encoding multiple paralogs of the replication helicase MCM and origins of replication are associated with mobile elements (Robinson and Bell 2007; Krupovic et al. 2010). Replicon fusion also is a plausible path from a single origin of replication that is typical of bacteria to multiple origins present in archaea and eukaryotes. However, all the evidence in support of frequent replicon fusion and the plausibility of replicon takeover notwithstanding, there is no evidence of displacement of the bacterial replication apparatus with the archaeal version introduced by mobile elements, or vice versa, displacement of the archaeal machinery with the bacterial version, despite the rapid accumulation of diverse bacterial and archaeal genome sequences. Thus, the displacement scenarios of DNA replication machinery evolution are so far not supported by comparative genomic data.Regardless of the nature of the DNA replication system (if any) in the LUCA and the underlying causes of the archaeo–bacterial dichotomy of replication machineries, the similarity between the archaeal and eukaryotic replication systems is striking (Leipe et al. 1999; Bell and Dutta 2002; Bohlke et al. 2002; Kelman and White 2005; Barry and Bell 2006). Thus, the archaeal replication system appears to be an ancestral version of the eukaryotic system and hence a good model for functional and structural studies aimed at gaining mechanistic insights into eukaryotic replication.

Table 1.

The relationship between archaeal and eukaryotic replication systems