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621.
622.
Delphine A. Aigoin Nicolas Devos Sanna Huttunen Michael S. Ignatov Juana M. Gonzalez‐Mancebo Alain Vanderpoorten 《Evolution; international journal of organic evolution》2009,63(12):3248-3257
The Macaronesian endemic flora has traditionally been interpreted as a relict of a subtropical element that spanned across Europe in the Tertiary. This hypothesis is revisited in the moss subfamily Helicodontioideae based on molecular divergence estimates derived from two independent calibration techniques either employing fossil evidence or using an Monte Carlo Markov Chain (MCMC) to sample absolute rates of nucleotide substitution from a prior distribution encompassing a wide range of rates documented across land plants. Both analyses suggest that the monotypic Madeiran endemic genus Hedenasiastrum diverged of other Helicodontioideae about 40 million years, that is, well before Macaronesian archipelagos actually emerged, in agreement with the relict hypothesis. Hedenasiastrum is characterized by a plesiomorphic morphology, which is suggestive of a complete morphological stasis over 40 million years. Macaronesian endemic Rhynchostegiella species, whose polyphyletic origin involves multiple colonization events, evolved much more recently, and yet accumulated many more morphological novelties than H. percurrens. The Macaronesian moss flora thus appears as a complex mix of ancient relicts and more recently dispersed, fast‐evolving taxa. 相似文献
623.
A new efficient expression system for Bacillus and its application to production of recombinant phytase 总被引:3,自引:0,他引:3
Janne Kerovuo Niklas von Weymarn Mira Povelainen Sanna Auer Andrei Miasnikov 《Biotechnology letters》2000,22(16):1311-1317
A new expression system was developed for Bacillus subtilis.This system uses a shuttle vector (B. subtilis– Eschericia coli) carrying a phosphate starvation-inducible promoter (pst) and on a fed-batch cultivation strategy. The pst-promoter proved to be very strong and retain its tight regulation also when present on a multi-copy plasmid. The expression system developed showed promising results when applied to the production of recombinant Bacillusphytase – phytase activity at the end of cultivation reached 28.7 U ml–1. 相似文献
624.
G Palmieri R Panu A Asole L Sanna V Farina 《Biological structures and morphogenesis》1988,1(4):142-146
The Authors have studied the morphological features and the proprioceptive nervous component in the coccygeus and levator ani muscles of the rabbit, using Ruffini's and Barker-Ip's impregnations. The coccygeus muscle originates from ischiatic spine and inserts on the last three sacral vertebrae and on the first four or five caudal vertebrae. The levator ani muscle originates from the ischiatic spine and the coccygeus muscle aponeurosis and inserts directly on the caudal vertebrae 3-5 or 4-6. The proprioceptive innervation in both muscles is constituted by muscle spindles and Golgi tendon organs with a typical structure. Muscle spindles are more numerous than Golgi tendon organs and the spindle density is higher in the levator ani muscle. 相似文献
625.
Aimaro Sanna 《Bioenergy Research》2014,7(1):36-47
Biofuels can play an important role in decreasing the use of fossil fuels, in particular in the transport sector, which absorbs about 30 % of the EU energy requirements. This review illustrates the motivations behind biofuel development, the government incentives and regulations and the current approaches on sustainable biomass conversion in Europe, and provides an overview on the major steps involved in thermochemical processes and on the issues challenging their deployment at large scale, with particular emphasis on the pyrolysis of biomass and bio-oil upgrading using conventional oil refinery settings. Distribution of sustainable biofuels in Europe and future prospects towards achieving success of transport biofuels were also addressed. The literature suggests that importing biofuels and increasing the cost of CO2 to at least €60/t CO2 will be necessary to meet the renewable obligation targets in the EU. Algae represent the future feedstock for biofuels but currently are limited by their high production costs and high N content. Pyrolysis is cost competitive compared to other technologies such as fermentation and gasification, but the quality of bio-oils requires upgrading mainly to lower their oxygen content and enhance their thermal stability. The recent advances in bio-oil upgrading using catalytic cracking and hydro-treating are very promising for the future deployment of advanced biofuels in the coming decades. However, significant investments in applied research and demonstration are still required to meet the 2020/2030 biofuel targets. 相似文献
626.
627.
Sanna A. Leppänen Ewald Altenhofer Andrew D. Liston Tommi Nyman 《Evolution; international journal of organic evolution》2013,67(5):1493-1502
Specialized trophic interactions in plant–herbivore–parasitoid food webs can spur “bottom–up” diversification if speciation in plants leads to host‐shift driven divergence in insect herbivores, and if the effect then cascades up to the third trophic level. Conversely, parasitoids that search for victims on certain plant taxa may trigger “top–down” diversification by pushing herbivores into “enemy‐free space” on novel hosts. We used phylogenetic regression methods to compare the relative importance of ecology versus phylogeny on associations between Heterarthrinae leafmining sawflies and their parasitoids. We found that: (1) the origin of leafmining led to escape from most parasitoids attacking external‐feeding sawflies; (2) the current enemies mainly consist of generalists that are shared with other leafmining taxa, and of more specialized lineages that may have diversified by shifting among heterarthrines; and (3) parasitoid–leafminer associations are influenced more by the phylogeny of the miners’ host plants than by relationships among miner species. Our results suggest that vertical diversifying forces have a significant—but not ubiquitous—role in speciation: many of the parasitoids have remained polyphagous despite niche diversification in the miners, and heterarthrine host shifts also seem to be strongly affected by host availability. 相似文献
628.
629.
Daniele Sanna Péter Buglyó Giovanni Micera Eugenio Garribba 《Journal of biological inorganic chemistry》2010,15(6):825-839
Potentiometric (pH titrations) and spectroscopic (electron paramagnetic resonance) methods have been used to determine the
thermodynamic stability constants of the various VO2+ complexes formed after the interaction of four insulin-enhancing vanadium compounds, [VO(6-mepic)2], cis-[VO(pic)2(H2O)], [VO(acac)2], and [VO(dhp)2], where 6-mepic, pic, acac, and dhp indicate the deprotonated forms of 6-methylpicolinic acid, picolinic acid, acetylacetone,
and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone, with high molecular mass [human serum apotransferrin (hTf) and human serum albumin (HSA)] and low molecular
mass (lactate) components of blood serum. In particular, log β values for the formation of (VO)hTf (13.0 ± 0.5), (VO)2hTf (25.5 ± 0.5), (VO)HSA (9.1 ± 1.0), (VO)
2
d
HSA (20.9 ± 1.0), cis-VO(dhp)2(hTf) (25.5 ± 0.6), cis-VO(dhp)2(HSA) (25.9 ± 0.6), (VO)hTf(lact) (14.5 ± 0.8), (VO)2hTf(lact)2 (28.5 ± 0.8), (VO)hTf(pic) (15.6 ± 0.8), and (VO)2hTf(pic)2 (30.4 ± 0.8) were determined. The values of the stability constants were used to compare the calculated composition of ternary
and quinary systems with that recently proposed by some of us through electron paramagnetic resonance and density functional
theory methods (Sanna et al. in Inorg. Chem. 49:174–187, 2010) and to predict the distribution of VO2+ ion in blood serum when one of the four insulin-enhancing vanadium compounds studied, [VO(carrier)2], is administered. 相似文献
630.