The full-length c DNA of a protease gene from a marine annelid Arenicola cristata was amplified through rapid amplification of c DNA ends technique and sequenced. The size of the c DNA was 936 bp in length, including ...The full-length c DNA of a protease gene from a marine annelid Arenicola cristata was amplified through rapid amplification of c DNA ends technique and sequenced. The size of the c DNA was 936 bp in length, including an open reading frame encoding a polypeptide of 270 amino acid residues. The deduced amino acid sequnce consisted of pro- and mature sequences. The protease belonged to the serine protease family because it contained the highly conserved sequence GDSGGP. This protease was novel as it showed a low amino acid sequence similarity(< 40%) to other serine proteases. The gene encoding the active form of A. cristata serine protease was cloned and expressed in E. coli. Purified recombinant protease in a supernatant could dissolve an artificial fibrin plate with plasminogen-rich fibrin, whereas the plasminogen-free fibrin showed no clear zone caused by hydrolysis. This result suggested that the recombinant protease showed an indirect fibrinolytic activity of dissolving fibrin, and was probably a plasminogen activator. A rat model with venous thrombosis was established to demonstrate that the recombinant protease could also hydrolyze blood clot in vivo. Therefore, this recombinant protease may be used as a thrombolytic agent for thrombosis treatment. To our knowledge, this study is the first of reporting the fibrinolytic serine protease gene in A. cristata.展开更多
Studies from both tropical and temperate systems show that scatter-hoarding rodents selectively disperse larger seeds farther from their source than smaller seeds,potentially increasing seedling establishment in large...Studies from both tropical and temperate systems show that scatter-hoarding rodents selectively disperse larger seeds farther from their source than smaller seeds,potentially increasing seedling establishment in larger-seeded plants.Size-biased dispersal is evident in many oaks(Quercus)and is true both across and within species.Here,we predict that intraspecifc variation in seed size also influences acorn dispersal by the Blue Jay(Cyanocitta cristata Linnaeus),but in an opposite manner.Blue Jays are gape-limited and selectively disperse smaller acorn species(e.g.pin oaks[Quercus palustris Münchh]),but often carry several acorns in their crop during a single dispersal event.We predict that jays foraging on smaller acorns will load more seeds per trip and disperse seeds to greater distances than when single acorns are carried in the bill.To test this,we presented free-ranging Blue Jays with pin oak acorns of different sizes over a 2-year period.In each of 16 experimental trials,we monitored the birds at a feeding station with remote cameras and determined the number of acorns removed and the distance acorns were dispersed when cached.Jays were significantly more likely to engage in multiple seed loading with smaller seeds in both years of the study.During the second year,these smaller acorns were dispersed farther than larger acorns,and during the first year,larger acorns were dispersed farther,revealing an inconsistent response to seed size during our study.We suggest that in some circumstances,multiple seed loading by Blue Jays may favor dispersal in some plant species.展开更多
基金supported by the National Natural Science Foundation of China (No. 30901779)the Natural Science Foundation of Shandong Province, China (No. ZR2009CM019)
文摘The full-length c DNA of a protease gene from a marine annelid Arenicola cristata was amplified through rapid amplification of c DNA ends technique and sequenced. The size of the c DNA was 936 bp in length, including an open reading frame encoding a polypeptide of 270 amino acid residues. The deduced amino acid sequnce consisted of pro- and mature sequences. The protease belonged to the serine protease family because it contained the highly conserved sequence GDSGGP. This protease was novel as it showed a low amino acid sequence similarity(< 40%) to other serine proteases. The gene encoding the active form of A. cristata serine protease was cloned and expressed in E. coli. Purified recombinant protease in a supernatant could dissolve an artificial fibrin plate with plasminogen-rich fibrin, whereas the plasminogen-free fibrin showed no clear zone caused by hydrolysis. This result suggested that the recombinant protease showed an indirect fibrinolytic activity of dissolving fibrin, and was probably a plasminogen activator. A rat model with venous thrombosis was established to demonstrate that the recombinant protease could also hydrolyze blood clot in vivo. Therefore, this recombinant protease may be used as a thrombolytic agent for thrombosis treatment. To our knowledge, this study is the first of reporting the fibrinolytic serine protease gene in A. cristata.
基金The authors recognize financial support of the US National Science Foundation(DEB-0642434 and DEB-0642504,RS,MS,NL,the Howard Hughes Medical Institute(AB,MS)The Fenner Endowment of the Department of Biology of Wilkes University(AB,MK,MS).
文摘Studies from both tropical and temperate systems show that scatter-hoarding rodents selectively disperse larger seeds farther from their source than smaller seeds,potentially increasing seedling establishment in larger-seeded plants.Size-biased dispersal is evident in many oaks(Quercus)and is true both across and within species.Here,we predict that intraspecifc variation in seed size also influences acorn dispersal by the Blue Jay(Cyanocitta cristata Linnaeus),but in an opposite manner.Blue Jays are gape-limited and selectively disperse smaller acorn species(e.g.pin oaks[Quercus palustris Münchh]),but often carry several acorns in their crop during a single dispersal event.We predict that jays foraging on smaller acorns will load more seeds per trip and disperse seeds to greater distances than when single acorns are carried in the bill.To test this,we presented free-ranging Blue Jays with pin oak acorns of different sizes over a 2-year period.In each of 16 experimental trials,we monitored the birds at a feeding station with remote cameras and determined the number of acorns removed and the distance acorns were dispersed when cached.Jays were significantly more likely to engage in multiple seed loading with smaller seeds in both years of the study.During the second year,these smaller acorns were dispersed farther than larger acorns,and during the first year,larger acorns were dispersed farther,revealing an inconsistent response to seed size during our study.We suggest that in some circumstances,multiple seed loading by Blue Jays may favor dispersal in some plant species.
