Horizontal gene transfer in silkworm, Bombyx mori

<p>Abstract</p> <p>Background</p> <p>The domesticated silkworm, <it>Bombyx mori</it>, is the model insect for the order Lepidoptera, has economically important values, and has gained some representative behavioral characteristics compared to its wild ancestor. The genome of <it>B. mori </it>has been fully sequenced while function analysis of <it>BmChi-h </it>and <it>BmSuc1 </it>genes revealed that horizontal gene transfer (HGT) maybe bestow a clear selective advantage to <it>B. mori</it>. However, the role of HGT in the evolutionary history of <it>B. mori </it>is largely unexplored. In this study, we compare the whole genome of <it>B. mori </it>with those of 382 prokaryotic and eukaryotic species to investigate the potential HGTs.</p> <p>Results</p> <p>Ten candidate HGT events were defined in <it>B. mori </it>by comprehensive sequence analysis using Maximum Likelihood and Bayesian method combining with EST checking. Phylogenetic analysis of the candidate HGT genes suggested that one HGT was plant-to- <it>B. mori </it>transfer while nine were bacteria-to- <it>B. mori </it>transfer. Furthermore, functional analysis based on expression, coexpression and related literature searching revealed that several HGT candidate genes have added important characters, such as resistance to pathogen, to <it>B. mori</it>.</p> <p>Conclusions</p> <p>Results from this study clearly demonstrated that HGTs play an important role in the evolution of <it>B. mori </it>although the number of HGT events in <it>B. mori </it>is in general smaller than those of microbes and other insects. In particular, interdomain HGTs in <it>B. mori </it>may give rise to functional, persistent, and possibly evolutionarily significant new genes.</p

Unusually Long Palindromes Are Abundant in Mitochondrial Control Regions of Insects and Nematodes

BACKGROUND: Palindromes are known to be involved in a variety of biological processes. In the present investigation we carried out a comprehensive analysis of palindromes in the mitochondrial control regions (CRs) of several animal groups to study their frequency, distribution and architecture to gain insights into the origin of replication of mtDNA. METHODOLOGY/PRINCIPAL FINDINGS: Many species of Arthropoda, Nematoda, Mollusca and Annelida harbor palindromes and inverted repeats (IRs) in their CRs. Lower animals like cnidarians and higher animal groups like chordates are almost devoid of palindromes and IRs. The study revealed that palindrome occurrence is positively correlated with the AT content of CRs, and that IRs are likely to give rise to longer palindromes. CONCLUSIONS/SIGNIFICANCE: The present study attempts to explain possible reasons and gives in silico evidence for absence of palindromes and IRs from CR of vertebrate mtDNA and acquisition and retention of the same in insects. Study of CRs of different animal phyla uncovered unique architecture of this locus, be it high abundance of long palindromes and IRs in CRs of Insecta and Nematoda, or short IRs of 10–20 nucleotides with a spacer region of 12–14 bases in subphylum Chelicerata, or nearly complete of absence of any long palindromes and IRs in Vertebrata, Cnidaria and Echinodermata

A study of room-temperature LixMn1.5Ni0.5O4 solid solutions

Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature Li(x)Mn(1.5)Ni(0.5)O(4) solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of Li(x)Mn(1.5)Ni(0.5)O(4) (0 ≤ x ≤ 1) cathode material consisting of three cubic phases: LiMn(1.5)Ni(0.5)O(4) (Phase I), Li(0.5)Mn(1.5)Ni(0.5)O(4) (Phase II) and Mn(1.5)Ni(0.5)O(4) (Phase III). A phase diagram capturing the structural changes as functions of both temperature and Li content was established. The work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance

Effect of transition metal substitution on elastoplastic properties of LiMn2O4 spinel

LiMn[subscript 2]O[subscript 4] (LMO) derivatives partially substituted with transition metals (e.g., Ni) have received attention for their higher energy density achieved at higher charge voltage than pure LMO, and may be attractive cathode candidates for emerging all solid state batteries. Accurate mechanical properties of these high voltage spinels are required for prediction of electrode and electrolyte fracture that may compromise battery lifetime and performance. Here, we quantified the Young’s elastic modulus E and hardness H for LMO, LiMn[subscript 1.5]Ni[subscript 0.5]O[subscript 4] (LMNO), and LiMn[subscript 1.5]Ni[subscript 0.42]Fe[subscript 0.08]O[subscript 4] (LMNFO) spinel microparticles via instrumented grid nanoindentation. Elastic modulus E and hardness H increased by more than 40% (up to 145 and 11 GPa, respectively) as a result of Ni or Ni/Fe substitution; such substitution also reduces the lattice parameter and increases the oxidization state of Mn. These results demonstrate how changes in transition metal occupancy can significantly affect the mechanical properties of LMO spinel, and provide critical parameters for designing against fracture in all solid state batteries.United States. Department of Energy. Office of Basic Energy Sciences (Award DE-SC0002633