Critical manifolds,travelling waves,and an example from population genetics

A generalized Morse index theory is used to study travelling waves in a natural selection-migration model for a diploid organism when the selective strength is weak.     

Molecular phylogenetics of Hippophae L. (Elaeagnaceae) based on the internal transcribed spacer (ITS) sequences of nrDNA

 The genus Hippophae comprises 7 species and 8 subspecies according to the latest classification, and has shown enormous ecological, nutrient and medicinal values. Here we analyzed the phylogenetic relationships among 15 taxa of the genus by comparing sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA). ITS sequences in Hippophae varied in length from 651 bp to 666 bp. The aligned sequences were 690 bp in length and 269 (39.0%) were variable sites with 150 being parsimony-informative. The amount of polymorphism observed within a taxon was extremely low in most taxa except for two putative hybrid species. The aligned sequences were analyzed by maximum parsimony (MP) and neighbor-joining (NJ) methods. In the strict consensus trees of parsimony analysis, the monophyly of Hippophae was supported by 100% bootstrap value. H. tibetana was at the basal position of the genus, and the remaining taxa formed two clades with high bootstrap support. The first clade included subspecies of H.␣rhamnoides and the other one consisted of remaining species. Parsimony analysis also suggested that the species H. tibetana, H. neurocarpa and H.␣salicifolia were all distinct. Although the sequence divergence among subspecies of H. rhamnoides was also remarkably high, the molecular data supported the monophyly of H. rhamnoides when H. rhamnoides subsp. gyantsensis Rousi was excxluded. The NJ trees showed essentially the same topology. The taxonomical arrangement that divided the genus into two sections was not supported based on the ITS sequences. However, the hybrid origin of H. goniocarpa and H. litangensis proposed previously was supported by the present ITS data. Received January 7, 2002; accepted May 10, 2002 Published online: November 22, 2002 Addresses of the authors: Kun Sun, Xuelin Chen, Ruijun Ma, Qin Wang, Institute of Botany, Northwest Normal University, Lanzhou 730070, China. Changbao Li, Song Ge (e-mail: gesong@ns.ibcas.ac.cn or song_ge@hotmail.com), Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.     

Plagiochila virginica A.Evans rather than P. dubia Lindenb. & Gottsche occurs in Macaronesia; placement in sect. Contiguae Carl is supported by ITS sequences of nuclear ribosomal DNA

 Plagiochila dubia Lindenb. & Gottsche is reduced to a synonym of the Neotropical P. patula (Sw.) Lindenb. Specimens from the Canary Islands and Madeira proved to belong to the eastern North American P. virginica A.Evans, new to Europe. Phylogenetic analyses of the internal transcribed spacer regions (ITS1-5.8S-ITS2) of nuclear ribosomal DNA of ten Plagiochila species produced four independent lineages that are well supported by all bootstrap analyses (maximum likelihood, maximum parsimony, and distance). These lineages correspond with the Plagiochila sections Arrectae, Contiguae, Cucullatae and Glaucescentes. Spruce's “Ramiflorae” and “Cauliflorae” may no longer be regarded as monophyletic units of Plagiochila. Received August 19, 2001 Accepted October 11, 2001     

Cold-induced phase separation for the simple and reliable extraction of sex hormones for subsequent LC-MS/MS analysis

Sex hormones, including androgens, estrogens, and progestogens, are important biomarkers for various diseases. Quantification of sex hormones is typically conducted by LC-MS/MS. At present, most methods require liquid-liquid extraction or solid phase extraction for sample preparation. However, these pretreatments are prone to compromise LC-MS/MS throughput. To improve on the current standard practices, we investigated cold-induced phase separation for sex hormone extraction. After protein precipitation with acetonitrile and adjusting the solution constitution with water, samples were stored at ?30°C for 10 min to generate two distinct phases: an acetonitrile-rich layer on top of a water-rich layer. During this process, the hydrophobic sex hormones spontaneously separate into the upper layer. This simple and reliable cold-induced phase separation-based LC-MS/MS methodology was used here to simultaneously detect estrone, estradiol, estriol, testosterone, androstenedione, dehydroepiandrosterone, progesterone, and 17-hydroxyprogesterone in serum. Validation of this method indicated satisfactory performance, including acceptable linearity, accuracy, precision, and tractability. Compared with the mainstream liquid-liquid extraction-based method, this new method exhibits significant progress in throughput, which shortens the time cost of sample preparation from 90 to 40 min. We propose that this method can be an excellent alternative for sex hormone analysis in routine clinical laboratories.     

Improved biomechanical metrics of cerebral vasospasm identified via sensitivity analysis of a 1D cerebral circulation model

Cerebral vasospasm (CVS) is a life-threatening condition that occurs in a large proportion of those affected by subarachnoid haemorrhage and stroke. CVS manifests itself as the progressive narrowing of intracranial arteries. It is usually diagnosed using Doppler ultrasound, which quantifies blood velocity changes in the affected vessels, but has low sensitivity when CVS affects the peripheral vasculature. The aim of this study was to identify alternative biomarkers that could be used to diagnose CVS. We used a 1D modelling approach to describe the properties of pulse waves that propagate through the cardiovascular system, which allowed the effects of different types of vasospasm on waveforms to be characterised at several locations within a simulated cerebral network. A sensitivity analysis empowered by the use of a Gaussian process statistical emulator was used to identify waveform features that may have strong correlations with vasospasm. We showed that the minimum rate of velocity change can be much more effective than blood velocity for stratifying typical manifestations of vasospasm and its progression. The results and methodology of this study have the potential not only to improve the diagnosis and monitoring of vasospasm, but also to be used in the diagnosis of many other cardiovascular diseases where cardiovascular waves can be decoded to provide disease characterisation.     

Structured elements drive extensive circular RNA translation

1. Download : Download high-res image (163KB)
2. Download : Download full-size image

     

White and Amber Light at Night Disrupt Sleep Physiology in Birds

Media player