Retinoic acid signaling restricts the cardiac progenitor pool   总被引：1，自引：0，他引：1  

Keegan BR  Feldman JL  Begemann G  Ingham PW  Yelon D 《Science (New York, N.Y.)》2005,307(5707):247-249

Organogenesis begins with specification of a progenitor cell population, the size of which provides a foundation for the organ's final dimensions. Here, we present a new mechanism for regulating the number of progenitor cells by limiting their density within a competent region. We demonstrate that retinoic acid signaling restricts cardiac specification in the zebrafish embryo. Reduction of retinoic acid signaling causes formation of an excess of cardiomyocytes, via fate transformations that increase cardiac progenitor density within a multipotential zone. Thus, retinoic acid signaling creates a balance between cardiac and noncardiac identities, thereby refining the dimensions of the cardiac progenitor pool.  相似文献   

Conformational states of sunflower (Helianthus annuus) Helianthinin: effect of heat and pH     

González-Pérez S  Vereijken JM  Merck KB  van Koningsveld GA  Gruppen H  Voragen AG 《Journal of agricultural and food chemistry》2004,52(22):6770-6778

The structure and solubility of helianthinin, the most abundant protein of sunflower seeds, was investigated as a function of pH and temperature. Dissociation of the 11S form (hexamer) into the 7S form (trimer) gradually increased with increasing pH from 5.8 to 9.0. High ionic strength (I = 250 mM) stabilizes the 11S form at pH > 7.0. Heating and low pH resulted in dissociation into the monomeric constituents (2-3S). Next, the 7S and 11S forms of helianthinin were isolated and shown to differ in their secondary and tertiary structure, and to have denaturation temperatures (T(d)) of 65 and 90 degrees C, respectively. Furthermore, the existence of two populations of the monomeric form of helianthinin with denaturation temperatures of 65 and 90 degrees C was described. This leads to the hypothesis that helianthinin can adopt two different conformational states: one with T(d) = 65 degrees C and a second with T(d) = 90 degrees C.  相似文献   

Tentative assignment of the potato serine protease inhibitor group as beta-II proteins based on their spectroscopic characteristics     

Pouvreau L  Gruppen H  van Koningsveld GA  van den Broek LA  Voragen AG 《Journal of agricultural and food chemistry》2004,52(25):7704-7710

Potato serine protease inhibitor (PSPI) is the most abundant protease inhibitor group in potato tuber. The investigated PSPI isoforms have a highly similar structure at both the secondary and the tertiary level. From the results described, PSPI is classified as a beta-II protein based on (1) the presence in the near-UV spectra of sharp peaks, indicating a rigid and compact protein; (2) the sharp transition from the native to the unfolded state upon heating (only 6 degrees C) monitored by a circular dichroism signal at 222 nm; and (3) the similarity in secondary structure to soybean trypsin inhibitor, a known beta-II protein, as indicated by a similar far-UV CD spectrum and a similar amide I band in the IR spectrum. The conformation of PSPI was shown also to be stable at ambient temperature in the pH range 4-7.5. Upon lowering the pH to 3.0, some minor changes in the protein core occur, as observed from the increase of the intensity of the phenylalanine peak in the near-UV CD spectrum.  相似文献   

Conduciveness of different soilless growing media to <Emphasis Type="Italic">Pythium</Emphasis> root and crown rot of cucumber under near-commercial conditions     

Dirk?Jan?van?der? GaagEmail author  Gerrit?Wever 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(1):31-41

Substrates made from rockwool, coir dust, pumice and perlite were compared for conduciveness to Pythium root and crown rot in cucumber under near-commercial conditions. Rockwool slabs of 7 cm height were more conducive to the Pythium disease than coir dust slabs, pumice or perlite under these conditions. Temperature, oxygen concentration and water content were determined in the substrates to explain differences in conduciveness between the inorganic substrates rockwool, pumice and perlite by differences in the physical conditions. Temperature and oxygen concentration could not explain the differences but the higher disease level on rockwool was associated with a much higher water content of this substrate as compared to coir dust, pumice and perlite. Increasing the height of the substrate from 7 to 14 cm greatly decreased the percentage of diseased plants due to the Pythium disease on rockwool but had no effect on the level of disease on perlite when the substrate had been infested 4 cm below the planting hole. This difference in response in substrate height between rockwool and perlite could be explained by a much larger decrease in water content with substrate height in the rockwool than in the perlite substrate. Temperature in the substrates were above 30 °C for more than 6 h on sunny days in June and reached maximum values of 35 °C or more. These temperatures are highly favourable for the pathogen P. aphanidermatum but will have adverse effects on most biocontrol strains.  相似文献   

Letter to the members of the Dutch Veterinary Medicine Societies Update new quality control management     

van den Ekker W  den Hertog A  Gostelie E  Verburgh M  Bouwhuis G  Hooijer GA  van Dongen F  Urlings B  van Mameren J  Hof M  Mandigers P 《Tijdschrift voor diergeneeskunde》2005,130(13):428-429

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Performance and welfare of Atlantic salmon,Salmo salar L. post-smolts in recirculating aquaculture systems: Importance of salinity and water velocity     

Trine Ytrestøyl  Harald Takle  Jelena Kolarevic  Sara Calabrese  Gerrit Timmerhaus  Bjørn O. Rosseland  Hans C. Teien  Tom O. Nilsen  Sigurd O. Handeland  Sigurd O. Stefansson  Lars O. E. Ebbesson  Bendik F. Terjesen 《Journal of the World Aquaculture Society》2020,51(2):373-392

Producing a larger post-smolt in recirculating aquaculture systems (RAS) could shorten the production time in sea cages and potentially reduce mortality. Knowledge of the biological requirements of post-smolts in closed-containment systems is however lacking. In the present study, the effects of salinity and water velocity on growth, survival, health, and welfare of Atlantic salmon reared in RAS were examined. Salmon smolts were stocked in three separate RAS with salinities of 12, 22, and 32‰ and subjected to high (1.0 body lengths per s⁻¹) or low (0.3 body lengths second⁻¹) water velocity. Growth performance, survival, welfare, and physiological stress responses were monitored until the fish reached a bodyweight of around 450 g. Growth rate was higher at lower salinity and higher water velocity generally had a positive effect on growth in all salinities. Feed conversion ratio was lower at 12‰ compared to the 22 and 32‰ when the fish were between 250 and 450 g. Higher mortality, elevated plasma cortisol levels, higher incidence of cataract, and a higher expression of stress-induced genes in the skin (iNOS, Muc5ac-like) indicated a negative effect of higher salinity on fish welfare. Male maturation was low (<1%), and not affected by salinity or water velocity.  相似文献   

Spatial suitability assessment for vineyard site selection based on fuzzy logic     

Golnaz Badr  Gerrit Hoogenboom  Michelle Moyer  Markus Keller  Richard Rupp  Joan Davenport 《Precision Agriculture》2018,19(6):1027-1048

Developing a sustainable agricultural production system requires knowledge of the climate, soil, and topography of the area of interest. This is especially relevant for wine grape (Vitis vinefera L.) production. The main objective of this study was the development of a comprehensive system to aid in the selection of suitable areas for grapevine cultivation. Included in this system were several bioclimatic indices, such as Growing Degree Days (GDD), Frost Free Days (FFD), and the Huglin Index (HI) calculated over a period of 30 years using daily weather data obtained from the University of Idaho’s Gridded Surface Meteorological (UI GSM) dataset. Soil data and topographical data were also included in the system. The bioclimatic indices, soil, and topographic data were then transformed using fuzzy logic, and suitability maps with scores ranging from 0 to 1 were developed. The final vineyard-potential scores were obtained by combining the soil, weather, and topographic potential scores with a range from 0 to 1, where 0 pertained to non-suitable areas and 1 referred to optimal sites. The maps were evaluated by comparing the range of suitability scores of existing vineyards in Washington State. The evaluation indicated that 97% of the established vineyards have a vineyard-potential score that ranges from 0.8 to 1. The results of this study revealed that 11% of the total study area had a high potential for wine grape production. This study was able to successfully employ fuzzy logic to help decision-makers, growers, and others with conducting a precise land assessment for wine grape production.  相似文献   

Report on the 43rd Annual Meeting of the DPG-Working Group Nematology     

Daub  Matthias  Hakl  Ulrike  Molendijk  Leendert PG  Schomaker  Corrie  Been  Thomas H  van Beers  Thea G  Jivishova  Sevda  Jivishov  Emil  Keusgen  Michael  Bluemel  Roman  Fischer  Daniel  Grundler  Florian MW  Reuther  Marie  Cappel  Sabrina  Bauer  Harald  Lang  Christian  Watrin  Cliff  den Nijs  Loes JMF  Van Bruggen  Anne-Sophie  Karssen  Gerrit  Kiewnick  Sebastian  Büchler  Urs  Roth  Irma  Frey  Jürg 《植物病害和植物保护杂志》2015,122(4):189-193

Journal of Plant Diseases and Protection -  相似文献   

Babesia--a historical overview     

Uilenberg G 《Veterinary parasitology》2006,138(1-2):3-10

The history of the genus Babesia is briefly outlined. The classical differences with the main other genus of non-pigment-forming hemoparasites, Theileria, are the absence of extra-erythrocytic multiplication (schizogony) in Babesia and the cycle in the vector tick, which includes transovarial transmission in Babesia but only transstadial transmission in Theileria. Also, the multiplication in the red cell of Babesia, by budding, most often results in two daughter cells (merozoites), while that of Theileria gives four merozoites, often as a Maltese cross. In particular this means that what is still commonly called Babesia microti is not a Babesia and that it would be just as logical to speak of human theileriosis as of babesiosis. The small piroplasm of horses, long known as Babesia equi, is already commonly designated as Theileria equi. However, on molecular grounds, it may be necessary to create a new genus for these parasites. The Babesia species of domestic animals are briefly discussed and presented in a table.  相似文献   

Institution, Legislation and Policy Analysis of China’s Wetland Protection     

Wen Ya-li Hou Fang-miao Gerrit Hazenberg 《中国林学(英文版)》2005,7(4):55-60

Wetland protection is a complex issue. In the executive system of wetland preservation, the central government is the main body of policy formulation and implementation. Although China has taken many steps to protect wetlands, there are still some institutional, legal and policy problems in the area of wetland protection. This article presents an analysis of these factors. First, the authors state and analyze the major legal and management problems currently hampering wetland protection in China. Then the authors believe that in the future, new problems of wetland protection will arise. Given the following three major aspects of wetland protection in China： i.e., the policy, law and management systems, this article provides some relevant suggestions in the area of policies and management.  相似文献