By culturing Galleria mellonella, Neoaplectana sp. (DD-136) and Achromobacter nematophilus separately under axenic conditions in the laboratory, it was possible to study the relationship between the bacterium and nematode during nematode parasitism of the insect.The infective-stage juveniles of the nematode were able to penetrate and kill the insect host without the presence of A. nematophilus or any other bacterium. However, without accompanying bacteria the nematode was unable to reproduce. Only when A. nematophilus or a possible replacement, such as Pseudomonas aeruginosa, was added to the blood did reproduction occur.The relationship between A. nematophilus and the nematode is considered a mutualistic one, since the bacterium lives and is protected inside the intestine of the free-living stage of the nematode and is transported and released by the nematode to the haemolymph of a host insect. The nematode, in turn, is dependent on the bacterium for reproduction.
The carbon‐13 NMR spectra of amber from several mining sites in the Dominican Republic show considerable variation. In certain cases the differences are sufficiently distinct to serve as a reliable indicator of provenance. The gradations within the resonances of unsaturated carbons may reflect the relative ages of the samples, because fossilization and diagenesis can remove this functionality.
DNA has been successfully isolated from both fossilized plant and animal tissues. The oldest material, dated as 25-40 million years old (Tertiary), was obtained from amber-entombed bees and termites. Tissues from both these insects yielded DNA of good quality, which could be amplified by the polymerase chain reaction (PCR) and subsequently sequenced, including the genes encoding 18S ribosomal RNA and 16S rRNA. We report here the extraction of DNA from a 120-135-million-year-old weevil (Nemonychidae, Coleoptera) found in Lebanese amber, PCR amplification of segments of the 18S rRNA gene and the internal transcribed spacer, and the corresponding nucleotide sequences of their 315- and 226-base-pair fragments, respectively. These sequences were used for preliminary phylogenetic analysis of the nemonychid's sequence with three extant coleopterans: Lecontellus pinicola (Nemonychidae), Hypera brunneipennis (Curculionidae) and the mealworm Tenebrio molitor (Tenebrionidae), and two extant dipterans: the fruitfly Drosophila melanogaster (Drosophilidae) and mosquito Aedes albopictus (Culicidae) for the purpose of ascertaining the origin of the extracted and amplified DNA. The results revealed that the PCR-amplified material is that of the extinct nemonychid weevil. This represents the oldest fossil DNA ever extracted and sequenced, extending by 80 million years the age of any previously reported DNA.
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