Stepwise evolution of resistance to toxic cardenolides via genetic substitutions in the Na+/K+ -ATPase of milkweed butterflies (lepidoptera: Danaini).

Despite the monarch butterfly (Danaus plexippus) being famous for its adaptations to the defensive traits of its milkweed host plants, little is known about the macroevolution of these traits. Unlike most other animal species, monarchs are largely insensitive to cardenolides, because their target site, the sodium pump (Na(+)/K(+) -ATPase), has evolved amino acid substitutions that reduce cardenolide binding (so-called target site insensitivity, TSI). Because many, but not all, species of milkweed butterflies (Danaini) are associated with cardenolide-containing host plants, we analyzed 16 species, representing all phylogenetic lineages of milkweed butterflies, for the occurrence of TSI by sequence analyses of the Na(+)/K(+) -ATPase gene and by enzymatic assays with extracted Na(+)/K(+) -ATPase.

A deletion defining a common Asian lineage of Mycobacterium tuberculosis associates with immune subversion.

Six major lineages of Mycobacterium tuberculosis appear preferentially transmitted amongst distinct ethnic groups. We identified a deletion affecting Rv1519 in CH, a strain isolated from a large outbreak in Leicester U.K.

Analysis of the virus population present in equine faeces indicates the presence of hundreds of uncharacterized virus genomes.

Virus DNA was isolated from horse faeces and cloned in a sequence-independent fashion. 268 clones were sequenced and 178140 nucleotides of sequence obtained. Statistical analysis suggests the library contains 17560 distinct clones derived from up to 233 different virus genomes.

Determination of platinum in serum and ultrafiltrate by flameless atomic absorption spectrophotometry.

A graphite furnace atomic absorption spectrophotometric assay, capable of accurately determining nanogram amounts of platinum in serum and ultrafiltrate, was developed. A sample serum or ultrafiltrate was acidified with nitric acid and heated to destroy the protein-platinum bond. A measured excess of ammonium 1-pyrrolidinedithiocarbamate was added, and the platinum complex was extracted into isopropylacetone.

Systemic chemotherapy for a primary germ cell tumor of the brain: a pharmacokinetic study.

Systemic administration of most chemotherapeutic agents has been assumed to be ineffective in the treatment of primary and metastatic brain tumors because these agents fail to cross the intact blood-brain barrier. However, agents which fail to penetrate the intact blood-brain barrier may penetrate it under conditions which include the presence of tumor in the central nervous system (CNS) and prior CNS irradiation. This paper reports the results of pharmacokinetic studies of bleomycin, cisplatin, and vinblastine in the CNS of a patient with a primary germ cell tumor of the brain who had received prior radiotherapy.