(n.) A shark of the genus Sphyrna or Zygaena, having the eyes set on projections from the sides of the head, which gives it a hammer shape. The Sphyrna zygaena is found in the North Atlantic. Called also hammer fish, and balance fish.
(n.) A fresh-water fish; the stone-roller.
(n.) An African fruit bat (Hypsignathus monstrosus); -- so called from its large blunt nozzle.
Example Sentences:
(1) Six additional divalent ions were tested for their ability to support hammerhead cleavage.
(2) However, a segment of approximately one-third of the PLMVd sequence has the elements required to form in the RNAs of both polarities the hammerhead structures proposed to act in the in vitro self-cleavage of avocado sunblotch viroid (ASBVd) and some satellite RNAs.
(3) When injected into the nucleus of frog oocytes, the ribozyme tRNA gene (ribtDNA) produces 'hammerhead' ribozymes which cleave the 5' sequences of U7snRNA, its target substrate, with high efficiency in vitro.
(4) All combinations of mutant substrate and mutant ribozyme were less active than the corresponding single mutations, suggesting that the hammerhead contains few, if any, replaceable tertiary interactions as are found in tRNA.
(5) Nine different hammerhead RNA self-cleaving domains consistent with the consensus secondary structure proposed by Keese and Symons (1987) were prepared and tested for cleavage.
(6) To investigate the binding properties of Mg2+ to the hammerhead ribozyme, cleavage rates and CD spectra for substrates containing inosine or guanosine at the cleavage site were measured.
(7) The hammerhead domains consist of a 34 nucleotide ribozyme bound to a complementary 13 nucleotide non-cleavable DNA substrate.
(8) Also, inversion of configuration at phosphorus is confirmed for a two-stranded hammerhead.
(9) Based on comparisons with self-cleaving plant viral satellite RNAs, hammerhead-shaped active structures, each containing one self-cleavage site, were proposed for the plus and minus ASBV RNAs and the newt RNA, but the stability of these hammerheads has been questioned.
(10) Here, we show that the purified full-length dimeric plus RNA, when incubated under our standard self-cleavage conditions, also self-cleaved by a double-hammerhead structure.
(11) The hammerhead ribozyme, as engineered by J. Haseloff and W. L. Gerlach [(1988) Nature (London) 334, 585-591], is an RNA molecule containing two regions of conserved nucleotides, a double helix, called helix II, which connects the two conserved regions, and flanking arms of variable sequence, which hybridize the ribozyme to its specific target.
(12) Insertion, deletion and base substitution mutations were carried out on a 58 base RNA containing the sequence of the single-hammerhead structure of the plus RNA of the virusoid of lucerne transient streak virus, and the effects on self-cleavage assessed.
(13) Analysis of the cleavage products of several of these hammerhead analogues confirms the involvement in the reaction of the 2'-OH adjacent to the cleavage site in the substrate, and demonstrates that some 2'-OH groups in the catalytic region strongly affect activity.
(14) The oligoribonucleotides were used as substrates in the study of the mechanism of cleavage of an RNA hammerhead domain having the phosphorothioate group at the cleavage site.
(15) These catalytic RNAs, or ribozymes, form a stem-loop secondary structure called a 'hammerhead' in which the catalytic (ribozyme) and substrate sequences are brought close together.
(16) Two sequence variants contained nucleotide changes in the double hammerhead-like self-cleaving structure identified in ASBV RNA.
(17) We have designed a hammerhead-type RNA system which consists of three RNA fragments for normal and modified complexes which contain a non-cleavable substrate with 2'-O-methylcytidine and a guanosine-to-inosine replaced enzyme.
(18) Although related to the hammerhead structure, sequences flanking the plus strand termini showed differences from the consensus and may be folded into a different structure containing a pseudo-knot.
(19) We have constructed and characterised in vitro a number of hammerhead ribozymes designed to cleave individual RNAs encoded by these genes.
(20) Substitutions of DNA for RNA in the various stems of a hammerhead ribozyme have been analyzed in vitro for kinetic efficiency.
Loggerhead
Definition:
(n.) A blockhead; a dunce; a numskull.
(n.) A spherical mass of iron, with a long handle, used to heat tar.
(n.) An upright piece of round timber, in a whaleboat, over which a turn of the line is taken when it is running out too fast.
(n.) A very large marine turtle (Thalassochelys caretta, / caouana), common in the warmer parts of the Atlantic Ocean, from Brazil to Cape Cod; -- called also logger-headed turtle.
(n.) An American shrike (Lanius Ludovicianus), similar to the butcher bird, but smaller. See Shrike.
Example Sentences:
(1) On foreign policy, a president who has been at loggerheads with the Israeli prime minister, Binyamin Netanyahu, over a Middle East peace process promised unflinching support for the state.
(2) Two powerful European commissioners are at loggerheads over whether to strengthen the emissions trading system, in order to maintain Europe's leadership on climate change.
(3) Cabinet ministers are at loggerheads over same-sex marriage, with Scott Morrison insisting there is no legal barrier to holding a referendum on the issue.
(4) Watson will try to strike a conciliatory tone but has been at loggerheads with the leadership during the election after an outburst about allegations of entryism into the party.
(5) Meanwhile, back in Westminster May has placed herself at loggerheads with a number of Conservative backbenchers who believe the government should pursue a soft Brexit maximising access to the single market – and who also want a parliamentary vote before article 50 is triggered.
(6) In London, MPs remain at loggerheads with the government over its refusal to make military plans public.
(7) The FA and Premier League are often seen as being at loggerheads but a Premier League spokesman stressed that, as Roddy's work emphasises, this is not the case.
(8) The EU commissioner for economic and financial affairs, Pierre Moscovici, said Greece and its creditors were still at loggerheads over reforms to Greek pensions and VAT rates, which lenders want to be toughened as a quid pro quo for giving Athens further bailout funds.
(9) George Osborne is at loggerheads with the work and pensions secretary over proposals to cut spending on universal credit by more than £1bn a year.
(10) Finance for 2013-20 has emerged as the most contentious issue with the US, China, India and the EU all at loggerheads.
(11) Newcastle’s manager has been at loggerheads with the France creator, but getting rid of him was a high-risk strategy given he did not sign a forward.
(12) The EU commissioner for economic and financial affairs, Pierre Moscovici, said Greece and its creditors were still at loggerheads over reforms to Greek pensions and VAT rates, which lenders want to be toughened as quid pro quo for giving Athens further bailout funds.
(13) Britain and Brussels have been at loggerheads for weeks over Theresa May's campaign to clamp down on so-called "benefits tourism".
(14) Yet he has set himself at loggerheads with the 1.3 million men and women who make up that staff.
(15) Worse, he was at loggerheads with the Islamist-led Congress that appointed him.
(16) The two governments have been at loggerheads for several months over Karzai’s refusal to sign an agreement governing a continued American security presence in the country after the bulk of Nato troops pull out later this year.
(17) In a sign of growing international solidarity over North Korea's recent behaviour, Sergei Lavrov, the foreign minister of Russia – which has been at loggerheads with the US over Syria – said: "There is no disagreement with the United States over North Korea."
(18) The pair had been at loggerheads in the days when Parker was co-founder of the original Napster filesharing service.
(19) In addition the Tory leader in Wales, Andrew RT Davies, has said he will vote for the UK to leave the EU, which puts him at loggerheads with the prime minister, David Cameron.
(20) By Tuesday afternoon, more than 780,000 comments had been submitted to the regulator over its proposed “open internet” rules that have cable companies, politicians, consumers and activists at loggerheads over the future of the internet.