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251.
Svante Pbo 《Trends in genetics : TIG》1999,15(12):679-M16
The origin, history, and singularity of our species has fascinated storytellers, philosophers and scientists throughout, and doubtless before, recorded history. Anthropology, the modern-era discipline that deals with these issues, is a notoriously contentious field, perhaps because the topic at hand – the nature of our own species – is one that is difficult or impossible to approach in an unbiased way. Recently, molecular genetics has increasingly contributed to this field. Here, I briefly discuss three areas where I believe molecular studies are likely to be of decisive importance in the future. These concern the questions of where and when our species originated, what the genetic background for characters that differ between us and apes is, and how the phenotypic traits that vary among human groups have evolved. 相似文献
252.
Ole Bennike Svante Björck Jens Böcher Louise Hansen Jan Heinemeier Barbara Wohlfarth 《Journal of Biogeography》1999,26(3):667-677
Aim The aim of this paper is to describe and interpret early Holocene floras and faunas. Location The floras and faunas come from various localities in North-east Greenland. Methods Sediment samples were wet sieved, and macrofossils picked out and dated by the AMS radiocarbon-dating method. Results Sediments, dated to the first centuries after the last glacial stage came to an abrupt end, contain a macroflora of bryophytes and a few herbs, and we suggest that these plant remains represent a pioneer vegetation entirely without woody plants. The named species of herbs are either confined to the northern parts of Greenland at present, or they become increasingly more important towards the north. Crowberry is the oldest woody plant recovered; it was present at 10.4 cal. ka BP , and it appears to have been common during the early Holocene in East Greenland. Main conclusions We suggest that the majority of the extant flora of vascular plants of East Greenland arrived by long distance dispersal during the Holocene. Some species may also have arrived during the late-glacial, and a few hardy species that are adapted to low summer temperatures may have survived the last glacial stage in nonglaciated areas. Some hardy animals may also have survived, but the majority of the fauna are considered Holocene immigrants. We suggest that migrating birds and storms, perhaps in combination, are under-appreciated dispersal vectors. 相似文献
253.
Marine macroalgae (seaweeds) consist of a diverse range of species with diverse morphology and bioactive properties. The potential for genetic improvement to increase the value of the production of such molecules and other economically important traits is likely to be high as procedures for cultivation of many species are well established, genetic diversity is often high, sexual propagation is often possible and seaweeds generally have a short generation time that allows rapid transition from one selected generation to the next. The need for genetic improvement has been voiced by industry for many years. Despite this, there is little published research describing seaweed genetic improvement methodology, results or impact. This review draws on knowledge from other groups of species and describes options, benefits and knowledge needed for the genetic improvement of macroalgae. In conclusion, the review highlights how a well-designed genetic improvement program, which targets one or a few select economically valuable traits whilst limiting inbreeding, could provide potentially large benefits for industries reliant on the culture of seaweeds. Progress will, to a large extent, rely on the magnitude of genetic variation for the trait in question. 相似文献
254.
Martinsson, S., Kjærandsen, J. & Sundberg, P. (2011). Towards a molecular phylogeny of the fungus gnat genus Boletina (Diptera: Mycetophilidae). —Zoologica Scripta, 40, 272–281. Boletina is a species rich genus of fungus gnats (Diptera: Mycetophilidae) with a mainly Holarctic distribution. The systematics within the genus has gained little attention and this is a first attempt to shed some light over the systematics of Boletina and to test the segregation of the genera Saigusaia and Aglaomyia from Boletina. The nuclear marker 28S and mitochondrial 16S, COI and CytB were amplified and sequenced for 23 taxa that were analysed separately and together with a broad sample of outgroup taxa obtained from GenBank, where also 18S sequences were added. Phylogenies were estimated using maximum likelihood, Bayesian inference and parsimony. We strengthen the hypothesized sister‐group relationship between Docosia and Boletina, but the genus Boletina as currently delimited appears to be paraphyletic and nested in a clade together with Aglaomyia, Coelosia and Gnoriste. The genus Saigusaia, on the other hand, seems to be well separated from Boletina. The Boletina erythropyga species group is consistently found as a distinct basal clade within Boletina s.l. The results obtained are otherwise ambiguous both for the taxa in focus and in some analyses globally with a statistically supported total breakdown of the traditional higher classification into tribes, subfamilies and even families. Interestingly, this breakdown almost disappeared when additional 18S sequences were added. 相似文献
255.
Alejandro Gonzalez-Voyer Svante Winberg Niclas Kolm 《Evolution; international journal of organic evolution》2009,63(9):2266-2274
Morphological traits are often genetically and/or phenotypically correlated with each other and such covariation can have an important influence on the evolution of individual traits. The strong positive relationship between brain size and body size in vertebrates has attracted a lot of interest, and much debate has surrounded the study of the factors responsible for the allometric relationship between these two traits. Here, we use comparative analyses of the Tanganyikan cichlid adaptive radiation to investigate the patterns of evolution for brain size and body size separately. We found that body size exhibited recent bursts of rapid evolution, a pattern that is consistent with divergence linked to ecological specialization. Brain weight on the other hand, showed no bursts of divergence but rather evolved in a gradual manner. Our results thus show that even highly genetically correlated traits can present markedly different patterns of evolution, hence interpreting patterns of evolution of traits from correlations in extant taxa can be misleading. Furthermore, our results suggest, contrary to expectations from theory, that brain size does not play a key role during adaptive radiation. 相似文献
256.
257.
Johan Hoffstedt Manabu Shimizu Svante Sjstedt Fredrik Lnnqvist 《Obesity (Silver Spring, Md.)》1995,3(5):447-457
The existence and relative importance of β3-adrenoceptors in man is still controversial. The aim of the present study was 1) to find further evidence for the existence of functional β3-adrenoceptors in human fat, and 2) to investigate factors that may influence this β3-adrenoceptor function. Fifty individuals were examined. Lipolysis mediated by the selective β3-adrenoceptor agonist CGP 12177 in omental fat cells correlated with the response in subcutaneous fat cells. However, lipolysis was more pronounced in omental as compared to subcutaneous adipocytes, the intrinsic activity for CGP 12177 was 41% and 33%, respectively, while dobutamine, terbutaline and norepinephrine were full agonists. Both the lipolytic response and the sensitivity to CGP 12177 correlated with the effects of norepinephrine in the omental fat cells (r2= 0. 68 and 0. 50, respectively, p=0. 0001). The β2-adrenoceptor mediated lipolytic response did also correlate with the responses induced by β1- and β2-agonists and by postreceptor acting agents. The antagonistic properties (pA2) of the β-adrenoceptor subtypes were also investigated. The pA2 for the selective β1- and β2-adrenoceptor antagonists versus CGP 12177-induced lipolysis were 2 to 3 log units lower than those for the β1-antagonist versus dobutamine or for the β2-antagonist versus terbutaline. Furthermore, bupranolol had a significantly better antagonistic effect (pA2 7. 17, p<0. 001) on the CGP 12177-induced lipolysis than had the β1- and β2-adrenoceptor antagonists (pA2 6. 26 and 6. 05, respectively). These data clearly support the existence of a third human β-adrenoceptor. Several factors may contribute to the contradictory β3-adrenoceptor results in man. The sensitivity of the different lipolytic systems vary considerably. Omental fat cells are preferable to subcutaneous cells for β3-adrenoceptor studies in man. The β3-responses are more attenuated in isolated fat cell preparations than in tissue fragments. Furthermore, as the β3-adrenoceptor activity correlates to the norepinephrine activity, more pronounced effects will be expected in catecholamine sensitive subjects. At present, the number of tools available for β3-adrenoceptor studies are limited, and the receptor is hard to study, why it is essential to perform β3-adrenoceptor studies under optimal conditions in order to obtain conclusive effects. 相似文献
258.
Svante Martinsson Ainara Achurra Marcus Svensson Christer Erséus 《Zoologica scripta》2013,42(6):612-622
The genetic and morphological variation within Rhyacodrilus falciformis Bretscher, 1901 (Clitellata: Naididae) in Europe was explored using an integrative approach, with three unlinked genetic markers [the mitochondrial cytochrome c oxidase subunit I (COI), the nuclear histone 3 (H3) and internal transcribed spacer region (ITS)] combined with morphology, to investigate whether this taxon constitutes a single or several species. Using Automatic Barcode Gap Discovery on the COI data set, the specimens were divided into seven clusters, used as hypothetical species that were further tested with the other data sources. Single‐gene trees were estimated for all three markers, using coalescence analysis and they were in many parts incongruent with each other. Only one of the clusters was supported by all trees; it was also morphologically differentiated from the other clusters by the shape of its modified penial chaetae. This group consists of two specimens from the Crotot Cave in south‐eastern France, and morphologically they fit a previously described but invalid variety, ‘pigueti’, which is here described as a new species, Rhyacodrilus pigueti Achurra & Martinsson sp. n. The study highlights the fact that a single data source (e.g. COI barcodes) seldom provides a sufficient basis for taxonomic decisions such as species delimitation. 相似文献
259.
Fatema Rahman Tra-Mi Nguyen Olayiwola A Adekoya Cristina Campestre Paolo Tortorella Ingebrigt Sylte Jan-Olof Winberg 《Journal of enzyme inhibition and medicinal chemistry》2021,36(1):819
Compounds containg catechol or bisphosphonate were tested as inhibitors of the zinc metalloproteases, thermolysin (TLN), pseudolysin (PLN) and aureolysin (ALN) which are bacterial virulence factors, and the human matrix metalloproteases MMP-9 and −14. Inhibition of virulence is a putative strategy in the development of antibacterial drugs, but the inhibitors should not interfere with human enzymes. Docking indicated that the inhibitors bound MMP-9 and MMP-14 with the phenyl, biphenyl, chlorophenyl, nitrophenyl or methoxyphenyl ringsystem in the S1′-subpocket, while these ringsystems entered the S2′- or S1 -subpockets or a region involving amino acids in the S1′- and S2′-subpockets of the bacterial enzymes. An arginine conserved among the bacterial enzymes seemed to hinder entrance deeply into the S1′-subpocket. Only the bisphosphonate containing compound RC2 bound stronger to PLN and TLN than to MMP-9 and MMP-14. Docking indicated that the reason was that the conserved arginine (R203 in TLN and R198 in PLN) interacts with phosphate groups of RC2. 相似文献
260.
Svante Brandänge Lars Lindblom 《Biochemical and biophysical research communications》1979,91(3):991-996
The second of the two reaction steps involved in the metabolic transformation of (?)-nicotine to (?)-cotinine , the oxidation of the intermediate is mediated mainly, if not solely, by the enzyme aldehyde oxidase (EC 1.2.3.1). Of the molecular species that constitute , nicotine Δ1′(5′) iminium ion appears to serve as the substrate. The enzyme has a strong affinity for , as shown in a study on the inhibition of the oxidation of 3-(aminocarbonyl)-1-methylpyridinium chloride. This study gave a value of Ki = 6 μM; Km = 2 μM (pH 7.4). Mainly in view of this finding, “iminium oxidase” seems to be a more adequate name than “aldehyde oxidase” for this enzyme. 相似文献