Thymidine kinases in archaea

Twenty-six fully sequenced archaeal genomes were searched for genes coding for putative deoxyribonucleoside kinases (dNKs). We identified only 5 human-like thymidine kinase 1 genes (TK1s) and none for non-TK1 kinases. Four TK1s were identified in the Euryarchaea and one was found in the Crenarchaea, while none was found in Nanoarchaeum. The identified TK1s have high identity to Gram-positive bacteria TK1s. The TK1s from archaea, Gram-positive bacteria and eukaryotes share the same common ancestor, while the TK1s from Gram-negative bacteria belong to a less-related subgroup. It seems that a functional deoxyribonucleoside salvage pathway is not crucial for the archaeal cell

Thymidine kinase diversity in bacteria

Thymidine kinases (TKs) appear to be almost ubiquitous and are found in nearly all prokaryotes, eukaryotes, and several viruses. They are the key enzymes in thymidine salvage and activation of several anti-cancer and antiviral drugs. We show that bacterial TKs can be subdivided into 2 groups. The TKs from Gram-positive bacteria are more closely related to the eukaryotic TK1 enzymes than are TKs from Gram-negative bacteria

Opiine Parasitoids (Hymenoptera: Braconidae) of Tropical Fruit Flies (Diptera: Tephritidae) of the Australian and South Pacific Region

Opiine wasps are well known larval and egg-larval parasitoids of dacine fruit flies, one of the most important insect pest groups of the South Pacific. For Australia, Papua New Guinea and other South Pacific island countries and territories, no regional synopsis is available for the opiines attacking fruit flies, despite their use in classical, inundative and manipulative biological control. We present a taxonomic synopsis and distribution and host records (44% of which are new) for each of the 15 species of dacine-parasitising opiine braconids found in the South Pacific. Species dealt with are Diachasmimorpha hageni (Fullaway), D. kraussii (Fullaway), D. longicaudata (Ashmead), D. tryoni (Cameron), Fopius arisanus (Sonan), F. deeralensis (Fullaway), F. ferrari Carmichael & Wharton, sp. n., F. illusorius (Fischer) , comb. n., F. schlingeri Wharton, Opius froggatti Fullaway, Psyttalia fijiensis (Fullaway), P. muesebecki (Fischer), P. novaguineensis (Szépligeti) and Utetes perkinsi (Fullaway). A potentially undescribed species, which may be a colour morph of F. vandenboschi (Fullaway), is diagnosed but not formally described. Fopius vandenboschi sensu stricto, Diachasmimorpha fullawayi Silvestri, Psyttalia concolor Szépligeti and P. incisi Silvestri have been liberated into the region but are not considered to have established: a brief diagnosis of each is included in event that undetected, low level populations do occur and are sampled. Biosteres illusorius Fischer is formally transferred to the genus Fopius. A single opiine specimen reared from a species of Bactrocera (Bulladacus) appears to be Utetes albimanus (Szépligeti), but damage to this specimen and to the holotype (the only previously known specimen) means that we can not confirm this species as a fruit fly parasite: a diagnosis of U. cf. albimanus is provided. Psyttalia novaguineensis could not be adequately separated from P. fijiensis using previously published characterisations and further work to resolve this complex is recommended. A key is provided to all taxa reared from fruit-infesting tephritids in the South Pacific region

ENERGY AND ENVIRONMENTAL ROLL CALL VOTING IN THE U.S. CONGRESS IN 1975 AND 1979

This article argues that the energy and environmental policy areas in Congress are no longer considered components of the government management dimension. The two policy areas have separated from the government management dimension constructed by Clausen and are now distinct and autonomous Congressional policy areas. The models of roll call voting for energy and environment issues are very different. Energy is tied more closely to technical considerations while environmental issues are more emotional and more closely tied to quality of life concerns. Copyright 1984 by The Policy Studies Organization.

Crystal fields and conduction electrons in praseodymium

The interactions between the crystal-field excitations, the phonons and the conduction electrons in Pr have been studied further. The low-energy satellites to the crystal-field excitations, which are believed to be associated with propagating paramagnon modes in the conduction-electron gas, appear to be quenched by a magnetic field, which also induces a strong hybridization with the phonons

Nucleotide pools dictate the identity and frequency of ribonucleotide incorporation in mitochondrial DNA

Previous work has demonstrated the presence of ribonucleotides in human mitochondrial DNA (mtDNA) and in the present study we use a genome-wide approach to precisely map the location of these. We find that ribonucleotides are distributed evenly between the heavy- and light-strand of mtDNA. The relative levels of incorporated ribonucleotides reflect that DNA polymerase γ discriminates the four ribonucleotides differentially during DNA synthesis. The observed pattern is also dependent on the mitochondrial deoxyribonucleotide (dNTP) pools and disease-causing mutations that change these pools alter both the absolute and relative levels of incorporated ribonucleotides. Our analyses strongly suggest that DNA polymerase γ-dependent incorporation is the main source of ribonucleotides in mtDNA and argues against the existence of a mitochondrial ribonucleotide excision repair pathway in human cells. Furthermore, we clearly demonstrate that when dNTP pools are limiting, ribonucleotides serve as a source of building blocks to maintain DNA replication. Increased levels of embedded ribonucleotides in patient cells with disturbed nucleotide pools may contribute to a pathogenic mechanism that affects mtDNA stability and impair new rounds of mtDNA replication