Plant development is a process from germination of seed to vegetative growth, flower initiation and development, fertilization and finally to the next generation seed formation. A lot of achievements have been obtai...Plant development is a process from germination of seed to vegetative growth, flower initiation and development, fertilization and finally to the next generation seed formation. A lot of achievements have been obtained in plant developmental biology in China. Since the 1990's, those young generation scientists returned to China from abroad to use molecular and genetic techniques to study morphological, physiological and biochemical process of plant development. The present paper reviews the progress in some research area of plant developmental biology in the past decades and also prospects the chance and future of plant developmental studies, due to the recent advances of plant genome sequencing and functional genomics in China under the international research background.展开更多
HIV-1 evolves strongly and undergoes geographic differentiation as it spreads in diverse host populations around the world.For instance,distinct genomic backgrounds can be observed between the pandemic subtype B,preva...HIV-1 evolves strongly and undergoes geographic differentiation as it spreads in diverse host populations around the world.For instance,distinct genomic backgrounds can be observed between the pandemic subtype B,prevalent in Europe and North-America,and its offspring clade B＇ in East Asia.Here we ask whether this differentiation affects the selection pressure experienced by the virus.To answer this question we evaluate selection pressure on the HIV-1 envelope protein gp120 at the level of individual codons using a simple and fast estimation method based on the ratio ka/ks of amino acid changes to synonymous changes.To validate the approach we compare results to those from a state-of-the-art mixed-effect method.The agreement is acceptable,but the analysis also demonstrates some limitations of the simpler approach.Further,we find similar distributions of codons under stabilizing and directional selection pressure in gp120 for subtypes B and B＇ with more directional selection pressure in variable loops and more stabilizing selection in the constant regions.Focusing on codons with increased ka/ks values in B＇,we show that these codons are scattered over the whole of gp120,with remarkable clusters of higher density in regions flanking the variable loops.We identify a significant statistical association of glycosylation sites and codons with increased ka/ks values.展开更多
Anatomical structure of differently originated seed envelopes in one-seeded indehiscent fruits of Urticaceae and Asteraceae members is studied using light and scanning electron microscopes. It was found that in anthoc...Anatomical structure of differently originated seed envelopes in one-seeded indehiscent fruits of Urticaceae and Asteraceae members is studied using light and scanning electron microscopes. It was found that in anthocarps and involucrate fruits of both families the relations between the primary （pericarp） and secondary fruit envelopes （perianth and/or involucre） were composed under complexification （union） type, and not as substitution. Numerous examples of non-homologous resemblance in fruit envelope structure indicate a high degree of adaptability of certain histological types, recurring on a different morphological basis in different phyletic lines within a family. These tissue complexes represent widely occurring types of the pericarp （Utricaceae） or pericarp and seed coat tissue union （Asteraceae）. This evolutionary repetition or pseudocyclic resemblance is apparently another common regularity of one-seeded indehiscent fruits evolution in addition to those enumerated in general by Zohary （1950）.展开更多
文摘Plant development is a process from germination of seed to vegetative growth, flower initiation and development, fertilization and finally to the next generation seed formation. A lot of achievements have been obtained in plant developmental biology in China. Since the 1990's, those young generation scientists returned to China from abroad to use molecular and genetic techniques to study morphological, physiological and biochemical process of plant development. The present paper reviews the progress in some research area of plant developmental biology in the past decades and also prospects the chance and future of plant developmental studies, due to the recent advances of plant genome sequencing and functional genomics in China under the international research background.
基金Deutsche Forschungsgemeinschaft(http://www.dfg.de),grant TRR60/A6the University of Duisburg-Essen(http://www.uni-due.de)the Chinese Key National Science and Technology Program in the 12th Five-YearPeriod,grant 2012ZX10001006-002
文摘HIV-1 evolves strongly and undergoes geographic differentiation as it spreads in diverse host populations around the world.For instance,distinct genomic backgrounds can be observed between the pandemic subtype B,prevalent in Europe and North-America,and its offspring clade B＇ in East Asia.Here we ask whether this differentiation affects the selection pressure experienced by the virus.To answer this question we evaluate selection pressure on the HIV-1 envelope protein gp120 at the level of individual codons using a simple and fast estimation method based on the ratio ka/ks of amino acid changes to synonymous changes.To validate the approach we compare results to those from a state-of-the-art mixed-effect method.The agreement is acceptable,but the analysis also demonstrates some limitations of the simpler approach.Further,we find similar distributions of codons under stabilizing and directional selection pressure in gp120 for subtypes B and B＇ with more directional selection pressure in variable loops and more stabilizing selection in the constant regions.Focusing on codons with increased ka/ks values in B＇,we show that these codons are scattered over the whole of gp120,with remarkable clusters of higher density in regions flanking the variable loops.We identify a significant statistical association of glycosylation sites and codons with increased ka/ks values.
文摘Anatomical structure of differently originated seed envelopes in one-seeded indehiscent fruits of Urticaceae and Asteraceae members is studied using light and scanning electron microscopes. It was found that in anthocarps and involucrate fruits of both families the relations between the primary （pericarp） and secondary fruit envelopes （perianth and/or involucre） were composed under complexification （union） type, and not as substitution. Numerous examples of non-homologous resemblance in fruit envelope structure indicate a high degree of adaptability of certain histological types, recurring on a different morphological basis in different phyletic lines within a family. These tissue complexes represent widely occurring types of the pericarp （Utricaceae） or pericarp and seed coat tissue union （Asteraceae）. This evolutionary repetition or pseudocyclic resemblance is apparently another common regularity of one-seeded indehiscent fruits evolution in addition to those enumerated in general by Zohary （1950）.
