Solid/Gas In Crystallo Reactivity of an Ir(I) Methylidene Complex

In crystallo stabilization of known, but solution unstable, methylidene complex [Ir(tBu-PONOP)(═CH2)][BArF4] allows single-crystal to single-crystal solid/gas reactivity associated with the {Ir═CH2} group to be studied. Addition of H2 results in [Ir(tBu-PONOP)(H)2][BArF4]; exposure to CO forms iridium(I) carbonyl [Ir(tBu-PONOP)(CO)][BArF4], and reaction with NH3 gas results in the formation of methylamine complex [(tBu-PONOP)Ir(NH2Me)][BArF4] via an aminocarbene intermediate. Periodic density functional theory and electronic structure analyses confirm the Ir═CH2 bond character but with a very low barrier to rotation around the Ir═CH2 bond. Calculations show that addition of NH3 to the electrophilic alkylidene carbon gives an initial ammonium ylid intermediate. Stepwise N–H and C–H transfers then form the aminocarbene intermediate as a kinetic product from which two successive C–H couplings lead to the more stable methylamine product

Middleborns disadvantaged? testing birth-order effects on fitness in pre-industrial finns

Parental investment is a limited resource for which offspring compete in order to increase their own survival and reproductive success. However, parents might be selected to influence the outcome of sibling competition through differential investment. While evidence for this is widespread in egg-laying species, whether or not this may also be the case in viviparous species is more difficult to determine. We use pre-industrial Finns as our model system and an equal investment model as our null hypothesis, which predicts that (all else being equal) middleborns should be disadvantaged through competition. We found no overall evidence to suggest that middleborns in a family are disadvantaged in terms of their survival, age at first reproduction or lifetime reproductive success. However, when considering birth-order only among same-sexed siblings, first-, middle-and lastborn sons significantly differed in the number of offspring they were able to rear to adulthood, although there was no similar effect among females. Middleborn sons appeared to produce significantly less offspring than first-or lastborn sons, but they did not significantly differ from lastborn sons in the number of offspring reared to adulthood. Our results thus show that taking sex differences into account is important when modelling birth-order effects. We found clear evidence of firstborn sons being advantaged over other sons in the family, and over firstborn daughters. Therefore, our results suggest that parents invest differentially in their offspring in order to both preferentially favour particular offspring or reduce offspring inequalities arising from sibling competition

cDNA and gene nucleotide sequence of porcine plasminogen activator.

We have isolated cDNA and genomic clones coding for porcine plasminogen activator (urokinase, uPA). The cDNA is 2375 nucleotides long: it consists of a 5'-non-coding region (104 nucleotides), an open reading frame of 1329 nucleotides, and 3'-non-coding region of 942 nucleotides apart from the poly A tail. The genomic segment corresponding to the transcribed sequence is 5.85 kb long; it is composed of 11 exons and 10 introns. The 5'-flanking genomic region contains a number of sequences of potential regulatory significance, including possible hormone receptor binding sites and a sequence which we tentatively propose may be involved in activation of transcription by cAMP. The full sequence of both cDNA and genomic clones, the latter including 1.3 kb of flanking region, is presented and discussed, and the deduced amino acid sequence compared with that of human uPA