Sequencing and Analysis of the Mediterranean Amphioxus (Branchiostoma lanceolatum) Transcriptome

BACKGROUND: The basally divergent phylogenetic position of amphioxus (Cephalochordata), as well as its conserved morphology, development and genetics, make it the best proxy for the chordate ancestor. Particularly, studies using the amphioxus model help our understanding of vertebrate evolution and development. Thus, interest for the amphioxus model led to the characterization of both the transcriptome and complete genome sequence of the American species, Branchiostoma floridae. However, recent technical improvements allowing induction of spawning in the laboratory during the breeding season on a daily basis with the Mediterranean species Branchiostoma lanceolatum have encouraged European Evo-Devo researchers to adopt this species as a model even though no genomic or transcriptomic data have been available. To fill this need we used the pyrosequencing method to characterize the B. lanceolatum transcriptome and then compared our results with the published transcriptome of B. floridae. RESULTS: Starting with total RNA from nine different developmental stages of B. lanceolatum, a normalized cDNA library was constructed and sequenced on Roche GS FLX (Titanium mode). Around 1.4 million of reads were produced and assembled into 70,530 contigs (average length of 490 bp). Overall 37% of the assembled sequences were annotated by BlastX and their Gene Ontology terms were determined. These results were then compared to genomic and transcriptomic data of B. floridae to assess similarities and specificities of each species. CONCLUSION: We obtained a high-quality amphioxus (B. lanceolatum) reference transcriptome using a high throughput sequencing approach. We found that 83% of the predicted genes in the B. floridae complete genome sequence are also found in the B. lanceolatum transcriptome, while only 41% were found in the B. floridae transcriptome obtained with traditional Sanger based sequencing. Therefore, given the high degree of sequence conservation between different amphioxus species, this set of ESTs may now be used as the reference transcriptome for the Branchiostoma genus

An expert-curated global database of online newspaper articles on spiders and spider bites

Mass media plays an important role in the construction and circulation of risk perception associated with animals. Widely feared groups such as spiders frequently end up in the spotlight of traditional and social media. We compiled an expert-curated global database on the online newspaper coverage of human-spider encounters over the past ten years (2010-2020). This database includes information about the location of each human-spider encounter reported in the news article and a quantitative characterisation of the content-location, presence of photographs of spiders and bites, number and type of errors, consultation of experts, and a subjective assessment of sensationalism. In total, we collected 5348 unique news articles from 81 countries in 40 languages. The database refers to 211 identified and unidentified spider species and 2644 unique human-spider encounters (1121 bites and 147 as deadly bites). To facilitate data reuse, we explain the main caveats that need to be made when analysing this database and discuss research ideas and questions that can be explored with it.Peer reviewe

cis-(Benzenethiolato)bis(tert-butyl isocyanide)carbonyl(cyclopentadienyl)molybdenum(II), [Mo(C6H5S)(C5H9N)(2)-(C5H5)(CO)]

International audienceIn [CpMo(SPh)(CO)(CNtBu)2], Cp = η5-C5H5, the Mo atom adopts conventional four-legged piano-stool coordination geometry; a pair of cis CNtBu ligands, together with carbonyl and benzenethiolato groups, make up the base. The Mo-CNtBu bond lengths [2.053 (4) Å trans to S, 2.086 (4) Å trans to CO] show a small but significant difference

Activation of propargylic alcohols by dimolybdenum tris(mu-thiolate) complexes: Influence of the substituents R in HC CCR2(OH)-vinylidene/allenylidene transformation. Reactivity of allenylidene complexes

Reaction of the bis(nitrile) complex [Mo2Cp2(mu-SMe)(3)(NCMe)(2)](BF4) ( 1) with dimethylpropargylic alcohol, HC CCMe2(OH), at room temperature in dichloromethane produced good yields of the mu-alkynol species [Mo2Cp2(mu-SMe)(3){mu-CHCCMe2(OH)}](BF4) (2a) through replacement of the two acetonitrile ligands in 1 by the alkynol. The NMR spectra of 2a indicate a l-g 1: g 1 coordination mode for the alkyne which is thereby incorporated into a dimetallacyclobutene ring like that found here by X-ray diffraction (XRD) analysis of the related complex [Mo2Cp2(mu-SMe)(3)(mu-eta(1):eta(1)-CHCCO2Me)](BPh4) (2b). When 2a was stirred with Et3N at room temperature in dichloromethane, deprotonation gave high yields of the mu-3-hydroxyalkynyl derivative [Mo2Cp2(mu-SMe)(3){mu-eta(1):eta(2)-CCCMe2(OH)}] (3), together with small amounts of the already-known vinylacetylide [Mo2Cp2(mu-SMe)(3){mu-eta(1):eta(2)-CCC(Me)CH2}] (4) resulting from dehydration of 3. Treatment of 3 with 1 equiv. of HBF4 OEt2 in diethyl ether at room temperature gave the 3-hydroxyvinylidene derivative [ Mo2Cp2(mu-SMe)(3){mu-eta(1):eta(2)-CCHCMe2(OH)}](BF4) (5) as the major product, together with other minor products [Mo2Cp2(mu-SMe)(3){mu-eta(1):eta(2)-CCHC(Me) CH2}](BF4) (6), [Mo2Cp2(mu-SMe)(3)(mu-eta(1):eta(2)-CCCMe2)]( BF4) (7), [ Mo2Cp2(mu-SMe)(3)(mu-eta(1):eta(CCH2)-C-2)]( BF4) (8), [Mo2Cp2(mu-SMe)(3){mu-eta(1):eta(2)-CCH(CHMe2)}](BF4) (9) and [Mo2Cp2(mu-SMe)(3)(mu-O)](BF4) (10). The vinylidene (6) and allenylidene (7) species resulted from dehydration of the 3-hydroxyvinylidene complex 5 whereas the vinylidene derivative 8 was formed by deketonisation of 5. When 3 reacted with a large excess of HBF4 center dot OEt2 in dichloromethane, the 3-isopropylvinylidene complex 9 was obtained nearly quantatively via a H-center dot radical process. When left for several days CD2Cl2 solutions of 5 afforded mainly the vinylidene species 8 by deketonisation and the side-oxoproduct [Mo2Cp2(mu-SMe)(3)(mu-O)](BF4) (10) by hydrolysis or reaction with oxygen. Addition of nucleophiles (H-, OMe-, OH-, SMe-) to the allenylidene complex [Mo2Cp2(mu-SMe)(3)(mu-eta(1):eta(2)-CCCPh2)](BF4) (11) resulted in the formation of the corresponding mu-acetylide derivatives [Mo2Cp2(mu-SMe)(3)(mu-eta(1):eta(2)-CCCRPh2)][R = H (12), OMe (16a), OH (17), SMe (16b)], which by further reaction with tetrafluoroboric acid afforded either the vinylidene species [Mo2Cp2(mu-SMe)(3){mu-eta(1):eta(CH)-C-2( CRPh2)}](BF4) when R = H (13), or the starting complex 11 when R is a leaving group (OMe). Reaction of 13 with Na(BH4) gave the mu-alkylidyne complex [Mo2Cp2(mu-SMe)(3)(mu-eta(1)-CCH2CPh2H)] (14) by nucleophilic attack of H- at the C-beta carbon atom of the vinylidene chain. Proton addition at C-alpha in 14 led to the formation of a mu-vinylidene compound 15 containing an agostic C-H bond. New complexes have been characterised by elemental analyses and spectroscopic methods, supplemented for 2b and 3 by X-ray diffraction studies.

Spawning Induction and Embryo Micromanipulation Protocols in the Amphioxus Branchiostoma lanceolatum

International audienc

Electrochemical and theoretical investigations of the reduction of [Fe-2(CO)(5)L{mu-SCH2XCH2S}] complexes related to [FeFe] hydrogenase

The complexes [Fe-2(CO)(6){mu-SCH2N(R)CH2S}] (R = CH2CH2OCH3, 1a; R= Pr-i, 1b) and [Fe-2(CO)(6)(mu-pdt)] 2 (pdt = S(CH2)(3)S) are structural analogues of the [2Fe](H) subsite of [FeFe]H(2)ases. Electrochemical investigation of 1 and 2 in MeCN-[NBu4][PF6] under Ar and under CO has demonstrated that the reduction can be resolved into two one-electron transfer steps by using fast scan cyclic voltammetry. At slow scan rates the reduction of 1 tends towards a two-electron process owing to the fast disproportionation of the anion, while the two-electron reduction of 2 is clearly favoured in the presence of CO. Substitution of a CO ligand in 2 by a N-heterocyclic carbene results in the destabilisation of the anion. Thus, in MeCN-, thf- or CH2Cl2-[NBu4][PF6], the electrochemical reduction of Fe-2(CO)(5)L-NHC(mu-pdt)] 3 (L-NHC = 1,3-bis(methyl)-imidazol-2-ylidene, 3a; 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene, 3b) occurs in a single-step, two-electron process at moderate scan rates; under appropriate conditions this process can be separated into two one-electron steps. Density Functional Theory calculations successfully rationalize the effects of the S-to-S linkage on the electrochemistry of the complexes