We present a high-quality (>100× depth) Illumina genome sequence of the leaf-cutting ant Acromyrmex echinatior, a model species for symbiosis and reproductive conflict studies. We compare this genome with three previously sequenced genomes of ants from different subfamilies and focus our analyses on aspects of the genome likely to be associated with known evolutionary changes. The first is the specialized fungal diet of A. echinatior, where we find gene loss in the ant's arginine synthesis pathway, loss of detoxification genes, and expansion of a group of peptidase proteins. One of these is a unique ant-derived contribution to the fecal fluid, which otherwise consists of “garden manuring” fungal enzymes that are unaffected by ant digestion. The second is multiple mating of queens and ejaculate competition, which may be associated with a greatly expanded nardilysin-like peptidase gene family. The third is sex determination, where we could identify only a single homolog of the feminizer gene. As other ants and the honeybee have duplications of this gene, we hypothesize that this may partly explain the frequent production of diploid male larvae in A. echinatior. The fourth is the evolution of eusociality, where we find a highly conserved ant-specific profile of neuropeptide genes that may be related to caste determination. These first analyses of the A. echinatior genome indicate that considerable genetic changes are likely to have accompanied the transition from hunter-gathering to agricultural food production 50 million years ago, and the transition from single to multiple queen mating 10 million years ago.

The hypoxic environment imposes severe selective pressure on species living at high altitude. To understand the genetic bases of adaptation to high altitude in dogs, we performed whole-genome sequencing of 60 dogs including five breeds living at continuous altitudes along the Tibetan Plateau from 800 to 5100 m as well as one European breed. More than 1503 sequencing coverage for each breed provides us with a comprehensive assessment of the genetic polymorphisms of the dogs, including Tibetan Mastiffs. Comparison of the breeds from different altitudes reveals strong signals of population differentiation at the locus of hypoxia-related genes including endothelial Per-Arnt-Sim (PAS) domain protein 1 (EPAS1) and beta hemoglobin cluster. Notably, four novel nonsynonymous mutations specific to high-altitude dogs are identified at EPAS1, one of which occurred at a quite conserved site in the PAS domain. The association testing between EPAS1 genotypes and blood-related phenotypes on additional high-altitude dogs reveals that the homozygous mutation is associated with decreased blood flow resistance, which may help to improve hemorheologic fitness. Interestingly, EPAS1 was also identified as a selective target in Tibetan highlanders, though no amino acid changes were found. Thus, our results not only indicate parallel evolution of humans and dogs in adaptation to high-altitude hypoxia, but also provide a new opportunity to study the role of EPAS1 in the adaptive processes.

A synthetic gene encoding the fusion protein (AlaHyp) 51 -enhanced green fluorescent protein expressed in Nicotiana tabacum cells produced a fusion glycoprotein with all proline residues hydroxylated and substituted with an arabinogalactan polysaccharide. Alkaline hydrolysis of the fusion glycoprotein yielded a population of hydroxyproline (Hyp)-arabinogalactan polysaccharides ranging in size from 13 to 26 saccharide residues/Hyp, with a median size of 15-17 residues. We isolated a 15-residue Hyp-arabinogalactan for structure determination by sugar analyses and one-and two-dimensional nuclear magnetic resonance techniques that provided the assignment of proton and carbon signals of a small polysaccharide O-linked to the hydroxyl group of Hyp. The polysaccharide consisted of a 1,3-linked ␤-D-Galp backbone with a single 1,6-linked ␤-D-Galp ''kink.'' The backbone had two side chains of Galp substituted at position 3 with an arabinose di-or trisaccharide and at position 6 with glucuronic acid or rhamnosyl glucuronic acid. Energy-minimized space-filling molecular models showed hydrogen bonding within polysaccharides attached to repetitive Ala-Hyp and also between polysaccharides and the peptide backbone. Polysaccharides distorted the peptide Ramachandran angles consistent with the circular dichroic spectra of isolated (Ala-Hyp) 51 and its reversion to a polyproline II-like helix after deglycosylation. This first complete structure of a Hyp-arabinogalactan polysaccharide shows that computer-based molecular modeling of Hyp-rich glycoproteins is now feasible and supports the suggestion that small repetitive subunits comprise larger arabinogalactan polysaccharides.

Article:Burkart, C., Qiu, F., Brendel, S. et al. ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Please cite this article as: Burkart, C . ,Q i u ,F . ,B r e n d e l ,S . ,B e n e s ,V . ,H aåg, P., Labeit, S., This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. (700) extend from the Z -disc to the ends of the thick filaments, though, Sls(700) is only in the myofibril core. These shorter isoforms would contribute to the high stiffness of IFM. Other muscles in the thorax and legs have longer Sls isoforms with varying amounts of PEVK sequence; all span the I-band to the ends of the thick filaments. In muscles with longer Ibands, the proportion of PEVK sequence would determine the extensibility of the sarcomere. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

The flight muscles of many insects have a form of regulation enabling them to contract at high frequencies. The muscles are activated by periodic stretches at low Ca 2 þ levels. The same muscles also give isometric contractions in response to higher Ca 2 þ . We show that the two activities are controlled by different isoforms of TnC (F1 and F2) within single myofibrils. F1 binds one Ca 2 þ with high affinity in the C-terminal domain and F2 binds one Ca 2 þ in the C-terminal domain and one exchangeable Ca 2 þ in the N-terminal domain. We have characterised the isoforms and determined their effect on the development of stretch-activated and Ca 2 þ -activated tension by replacing endogenous TnC in Lethocerus flight muscle fibres with recombinant isoforms. Fibres with F1 gave stretch-activated tension and minimal isometric tension; those with F2 gave Ca 2 þ -dependent isometric tension and minimal stretch-activated tension. Regulation by a TnC responding to stretch rather than Ca 2 þ is unprecedented and has resulted in the ability of insect flight muscle to perform oscillatory work at low Ca 2 þ concentrations, a property to which a large number of flying insects owe their evolutionary success.