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  • 1
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    Haplodiploidy and the evolution of facultative sex ratios in a primitively eusocial bee (1991)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1991-10-18
    Description: In eusocial Hymenoptera, the haplodiploid system of sex determination creates relatedness asymmetries such that workers are more closely related on average to their sisters than to their brothers. For such societies, kin-selection theory and sex-ratio theory predict that workers maximize their inclusive fitness by biasing the investment sex ratio toward females. To test the prediction of sex-ratio biasing, relatedness asymmetries were experimentally manipulated in colonies of the primitively eusocial bee Augochlorella striata (Halictidae: Hymenoptera) by removing or not removing foundress queens. Queenright colonies (relatedness asymmetry present) produced a more female-biased sex ratio than did queenless colonies (relatedness asymmetry absent). Worker reproduction and unmated replacement queens can be discounted as alternative explanations. Workers therefore facultatively adjusted their colony's sex ratio and, in the presence of a relatedness asymmetry, biased the investment sex ratio toward their more closely related sisters and away from their more distantly related brothers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mueller, U G -- New York, N.Y. -- Science. 1991 Oct 18;254(5030):442-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17742231" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Ancient tripartite coevolution in the attine ant-microbe symbiosis (2003)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2003-01-18
    Description: The symbiosis between fungus-growing ants and the fungi they cultivate for food has been shaped by 50 million years of coevolution. Phylogenetic analyses indicate that this long coevolutionary history includes a third symbiont lineage: specialized microfungal parasites of the ants' fungus gardens. At ancient levels, the phylogenies of the three symbionts are perfectly congruent, revealing that the ant-microbe symbiosis is the product of tripartite coevolution between the farming ants, their cultivars, and the garden parasites. At recent phylogenetic levels, coevolution has been punctuated by occasional host-switching by the parasite, thus intensifying continuous coadaptation between symbionts in a tripartite arms race.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Currie, Cameron R -- Wong, Bess -- Stuart, Alison E -- Schultz, Ted R -- Rehner, Stephen A -- Mueller, Ulrich G -- Sung, Gi-Ho -- Spatafora, Joseph W -- Straus, Neil A -- New York, N.Y. -- Science. 2003 Jan 17;299(5605):386-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA. ccurrie@ku.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12532015" target="_blank"〉PubMed〈/a〉
    Keywords: Agaricales/growth & development/*physiology ; Animals ; Ants/microbiology/*physiology ; Ascomycota/physiology ; Bacterial Physiological Phenomena ; *Biological Evolution ; DNA, Fungal/analysis/genetics ; Hypocreales/classification/growth & development/isolation & ; purification/*physiology ; Phylogeny ; Sequence Analysis, DNA ; *Symbiosis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    The evolution of agriculture in ants (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1998-09-25
    Description: Cultivation of fungi for food by fungus-growing ants (Attini: Formicidae) originated about 50 million years ago. The subsequent evolutionary history of this agricultural symbiosis was inferred from phylogenetic and population-genetic patterns of 553 cultivars isolated from gardens of "primitive" fungus-growing ants. These patterns indicate that fungus-growing ants succeeded at domesticating multiple cultivars, that the ants are capable of switching to novel cultivars, that single ant species farm a diversity of cultivars, and that cultivars are shared occasionally between distantly related ant species, probably by lateral transfer between ant colonies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mueller -- Rehner -- Schultz -- New York, N.Y. -- Science. 1998 Sep 25;281(5385):2034-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉U. G. Mueller, Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama, and Department of Biology, University of Maryland, College Park, MD 20742, USA. S. A. Rehner, Smithsonian Tropical Research Institute, Apart.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9748164" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Evolutionary history of the symbiosis between fungus-growing ants and their fungi (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1994-12-09
    Description: The evolutionary history of the symbiosis between fungus-growing ants (Attini) and their fungi was elucidated by comparing phylogenies of both symbionts. The fungal phylogeny based on cladistic analyses of nuclear 28S ribosomal DNA indicates that, in contrast with the monophyly of the ants, the attine fungi are polyphyletic. Most cultivated fungi belong to the basidiomycete family Lepiotaceae; however, one ant genus, Apterostigma, has acquired a distantly related basidiomycete lineage. Phylogenetic patterns suggest that some primitive attines may have repeatedly acquired lepiotaceous symbionts. In contrast, the most derived attines have clonally propagated the same fungal lineage for at least 23 million years.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chapela, I H -- Rehner, S A -- Schultz, T R -- Mueller, U G -- New York, N.Y. -- Science. 1994 Dec 9;266(5191):1691-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17775630" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    The Genome Database for Rosaceae (GDR): year 10 update (2013)
    Oxford University Press
    Details
    Publication Date: 2013-12-29
    Description: The Genome Database for Rosaceae (GDR, http:/www.rosaceae.org ), the long-standing central repository and data mining resource for Rosaceae research, has been enhanced with new genomic, genetic and breeding data, and improved functionality. Whole genome sequences of apple, peach and strawberry are available to browse or download with a range of annotations, including gene model predictions, aligned transcripts, repetitive elements, polymorphisms, mapped genetic markers, mapped NCBI Rosaceae genes, gene homologs and association of InterPro protein domains, GO terms and Kyoto Encyclopedia of Genes and Genomes pathway terms. Annotated sequences can be queried using search interfaces and visualized using GBrowse. New expressed sequence tag unigene sets are available for major genera, and Pathway data are available through FragariaCyc, AppleCyc and PeachCyc databases. Synteny among the three sequenced genomes can be viewed using GBrowse_Syn. New markers, genetic maps and extensively curated qualitative/Mendelian and quantitative trait loci are available. Phenotype and genotype data from breeding projects and genetic diversity projects are also included. Improved search pages are available for marker, trait locus, genetic diversity and publication data. New search tools for breeders enable selection comparison and assistance with breeding decision making.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 6
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    Exact Ray Theory and its Application to the Reflection of Elastic Waves from Vertically Inhomogeneous Media (1970)
    Oxford University Press
    Details
    Publication Date: 1970-12-01
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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  • 7
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    Metal-induced DNA translocation leads to DNA polymerase conformational activation (2012)
    Oxford University Press
    Details
    Publication Date: 2012-04-15
    Description: Binding of the catalytic divalent ion to the ternary DNA polymerase β/gapped DNA/dNTP complex is thought to represent the final step in the assembly of the catalytic complex and is consequently a critical determinant of replicative fidelity. We have analyzed the effects of Mg 2+ and Zn 2+ on the conformational activation process based on NMR measurements of [methyl- 13 C]methionine DNA polymerase β. Unexpectedly, both divalent metals were able to produce a template base-dependent conformational activation of the polymerase/1-nt gapped DNA complex in the absence of a complementary incoming nucleotide, albeit with different temperature thresholds. This conformational activation is abolished by substituting Glu295 with lysine, thereby interrupting key hydrogen bonds necessary to stabilize the closed conformation. These and other results indicate that metal-binding can promote: translocation of the primer terminus base pair into the active site; expulsion of an unpaired pyrimidine, but not purine, base from the template-binding pocket; and motions of polymerase subdomains that close the active site. We also have performed pyrophosphorolysis studies that are consistent with predictions based on these results. These findings provide new insight into the relationships between conformational activation, enzyme activity and polymerase fidelity.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 8
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    Unfolding the HIV-1 reverse transcriptase RNase H domain - how to lose a molecular tug-of-war (2016)
    Oxford University Press
    Details
    Publication Date: 2016-03-01
    Description: Formation of the mature HIV-1 reverse transcriptase (RT) p66/p51 heterodimer requires subunit-specific processing of the p66/p66' homodimer precursor. Since the ribonuclease H (RH) domain contains an occult cleavage site located near its center, cleavage must occur either prior to folding or subsequent to unfolding. Recent NMR studies have identified a slow, subunit-specific RH domain unfolding process proposed to result from a residue tug-of-war between the polymerase and RH domains on the functionally inactive, p66' subunit. Here, we describe a structural comparison of the isolated RH domain with a domain swapped RH dimer that reveals several intrinsically destabilizing characteristics of the isolated domain that facilitate excursions of Tyr427 from its binding pocket and separation of helices B and D. These studies provide independent support for the subunit-selective RH domain unfolding pathway in which instability of the Tyr427 binding pocket facilitates its release followed by domain transfer, acting as a trigger for further RH domain destabilization and subsequent unfolding. As further support for this pathway, NMR studies demonstrate that addition of an RH active site-directed isoquinolone ligand retards the subunit-selective RH' domain unfolding behavior of the p66/p66' homodimer. This study demonstrates the feasibility of directly targeting RT maturation with therapeutics.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 9
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    Genomic, RNAseq, and Molecular Modeling Evidence Suggests That the Major Allergen Domain in Insects Evolved from a Homodimeric Origin (2013)
    Oxford University Press
    Details
    Publication Date: 2013-12-12
    Description: The major allergen domain (MA) is widely distributed in insects. The crystal structure of a single Bla g 1 MA revealed a novel protein fold in which the fundamental structure was a duplex of two subsequences (monomers), which had diverged over time. This suggested that the evolutionary origin of the MA structure may have been a homodimer of this smaller subsequence. Using publicly available genomic data, the distribution of the basic unit of this class of proteins was determined to better understand its evolutionary history. The duplication and divergence is examined at three distinct levels of resolution: 1) within the orders Diptera and Hymenoptera, 2) within one genus Drosophila , and 3) within one species Aedes aegypti . Within the family Culicidae, we have found two separate occurrences of monomers as independent genes. The organization of the gene family in A. aegypti shows a common evolutionary origin for its monomer and several closely related MAs. Molecular modeling of the A. aegypti monomer with the unique Bla g 1 fold confirms the distant evolutionary relationship and supports the feasibility of homodimer formation from a single monomer. RNAseq data for A. aegypti confirms that the monomer is expressed in the mosquito similar to other A. aegypti MAs after a blood meal. Together, these data support the contention that the detected monomer shares similar functional characteristics to related MAs in other insects. An extensive search for this domain outside of Insecta confirms that the MAs are restricted to insects.
    Electronic ISSN: 1759-6653
    Topics: Biology
    Published by Oxford University Press
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  • 10
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    Selective unfolding of one Ribonuclease H domain of HIV reverse transcriptase is linked to homodimer formation (2014)
    Oxford University Press
    Details
    Publication Date: 2014-05-01
    Description: HIV-1 reverse transcriptase (RT), a critical enzyme of the HIV life cycle and an important drug target, undergoes complex and largely uncharacterized conformational rearrangements that underlie its asymmetric folding, dimerization and subunit-selective ribonuclease H domain (RH) proteolysis. In the present article we have used a combination of NMR spectroscopy, small angle X-ray scattering and X-ray crystallography to characterize the p51 and p66 monomers and the conformational maturation of the p66/p66' homodimer. The p66 monomer exists as a loosely structured molecule in which the fingers/palm/connection, thumb and RH substructures are connected by flexible (disordered) linking segments. The initially observed homodimer is asymmetric and includes two fully folded RH domains, while exhibiting other conformational features similar to that of the RT heterodimer. The RH' domain of the p66' subunit undergoes selective unfolding with time constant ~6.5 h, consistent with destabilization due to residue transfer to the polymerase' domain on the p66' subunit. A simultaneous increase in the intensity of resonances near the random coil positions is characterized by a similar time constant. Consistent with the residue transfer hypothesis, a construct of the isolated RH domain lacking the two N-terminal residues is shown to exhibit reduced stability. These results demonstrate that RH' unfolding is coupled to homodimer formation.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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