Ancestral polyploidy in seed plants and angiosperms

Whole-genome duplication (WGD), or polyploidy, followed by gene loss and diploidization has long been recognized as an important evolutionary force in animals, fungi and other organisms, especially plants. The success of angiosperms has been attributed, in part, to innovations associated with gene or whole-genome duplications, but evidence for proposed ancient genome duplications pre-dating the divergence of monocots and eudicots remains equivocal in analyses of conserved gene order. Here we use comprehensive phylogenomic analyses of sequenced plant genomes and more than 12.6 million new expressed-sequence-tag sequences from phylogenetically pivotal lineages to elucidate two groups of ancient gene duplications-one in the common ancestor of extant seed plants and the other in the common ancestor of extant angiosperms. Gene duplication events were intensely concentrated around 319 and 192 million years ago, implicating two WGDs in ancestral lineages shortly before the diversification of extant seed plants and extant angiosperms, respectively. Significantly, these ancestral WGDs resulted in the diversification of regulatory genes important to seed and flower development, suggesting that they were involved in major innovations that ultimately contributed to the rise and eventual dominance of seed plants and angiosperms.     

OBSERVATIONS ON TEACHING ENGLISH WRITING IN CHINA

作者在武汉一所重点大学教授英语的经验表明，中国学生的英文写作普遍存在很大问题。中国加入世贸组织后，与外界打交道的机会越来越多，此外，许多大学生毕业后想继续到英语国家学习。英语写作能力的提高将有助于国际间的相互交流和理解，以及个人目标的实现。在本论文中，作者指出了导致英语写作能力差的主要原因．即受本国语言的影响太深，教学缺乏持续性，学生对写作态度不认真。针对这些原因作者提出了促进英语写作能力提高的6点想法。     

A new N-glucuronide metabolite of carbamazepine

Summary An N-glucuronide metabolite of carbamazepine was identified in the bile of the isolated perfused rat liver by means of permethylation, gas chromatography and mass spectrometry.This research was supported by grants from the National Institutes of Health (Nos. N01-NS-5-2328, AM-17665) and the James Whitcomb Riley Memorial Association (No. 74-15) and a grant from the Epilepsy, Foundation of America.     

Mutations in kelch-like 3 and cullin 3 cause hypertension and electrolyte abnormalities

Hypertension affects one billion people and is a principal reversible risk factor for cardiovascular disease. Pseudohypoaldosteronism type II (PHAII), a rare Mendelian syndrome featuring hypertension, hyperkalaemia and metabolic acidosis, has revealed previously unrecognized physiology orchestrating the balance between renal salt reabsorption and K(+) and H(+) excretion. Here we used exome sequencing to identify mutations in kelch-like 3 (KLHL3) or cullin 3 (CUL3) in PHAII patients from 41 unrelated families. KLHL3 mutations are either recessive or dominant, whereas CUL3 mutations are dominant and predominantly de novo. CUL3 and BTB-domain-containing kelch proteins such as KLHL3 are components of cullin-RING E3 ligase complexes that ubiquitinate substrates bound to kelch propeller domains. Dominant KLHL3 mutations are clustered in short segments within the kelch propeller and BTB domains implicated in substrate and cullin binding, respectively. Diverse CUL3 mutations all result in skipping of exon 9, producing an in-frame deletion. Because dominant KLHL3 and CUL3 mutations both phenocopy recessive loss-of-function KLHL3 mutations, they may abrogate ubiquitination of KLHL3 substrates. Disease features are reversed by thiazide diuretics, which inhibit the Na-Cl cotransporter in the distal nephron of the kidney; KLHL3 and CUL3 are expressed in this location, suggesting a mechanistic link between KLHL3 and CUL3 mutations, increased Na-Cl reabsorption, and disease pathogenesis. These findings demonstrate the utility of exome sequencing in disease gene identification despite the combined complexities of locus heterogeneity, mixed models of transmission and frequent de novo mutation, and establish a fundamental role for KLHL3 and CUL3 in blood pressure, K(+) and pH homeostasis.