Exine deprived pollen only coated with inline has been isolated and artificially germinated in Brassica L. In view of the lack of exine and germ furrows, the de-exined pollen is an interesting experimental system for ...Exine deprived pollen only coated with inline has been isolated and artificially germinated in Brassica L. In view of the lack of exine and germ furrows, the de-exined pollen is an interesting experimental system for studying pollen germination. This report focuses on the microscopic and ultrastructural changes in the aspects of polarization, predetermination of the germination site and new wall synthesis during the course of isolation and germination of the de-exined pollen. It was shown that the de-exined pollen was already in an active state and had established its polarity and germination sites prior to exine detachment. The germination sites were still localized at the region of the previous germ furrows even after exine detachment. The new wall deposited at the germination sites appeared to have an important morphogenetic role in setting a limit to the size of pollen tube diameter . These results support our assumption that the de-exined pollen may have an extensive application in the research of pollen biology.展开更多
Mangrove degradation must reduce carbon sequestration in recent years, thereby aggravating global warming.Thus, short-term impacts of human activity on mangrove ecosystems are cause for concern from local governments ...Mangrove degradation must reduce carbon sequestration in recent years, thereby aggravating global warming.Thus, short-term impacts of human activity on mangrove ecosystems are cause for concern from local governments and scientists. Mangroves sediments can provide detailed records of mangrove species variation in the last one hundred years, based on detailed 210 Pb data. The study traced the history of mangrove development and its response to environmental change over the last 140 years in two mangrove swamps of Guangxi, Southwest China. Average sedimentation rates were calculated to be 0.48 cm/a and 0.56 cm/a in the Yingluo Bay and the Maowei Sea, respectively. Chemical indicators（δ13Corg and C：N） were utilized to trace the contribution of mangrove-derived organic matter（MOM） using a ternary mixing model. Simultaneous use of mangrove pollen can help to supplement some of these limitations in diagenetic/overlap of isotopic signatures. We found that vertical distribution of MOM was consistent with mangrove pollen, which could provide similar information for tracing mangrove ecosystems. Therefore, mangrove development was reconstructed and divided into three stages： flourishing, degradation and re-flourishing/re-degradation period. The significant degradation, found in the period of 1968–1998 and 1907–2007 in the Yingluo Bay and the Maowei Sea, respectively, corresponding to a rapid increase of reclamation area and seawall length, rather than climate change as recorded in the region.展开更多
基金National Natural Science Foundation of China Science Foundation of State Education Commission of China.
文摘Exine deprived pollen only coated with inline has been isolated and artificially germinated in Brassica L. In view of the lack of exine and germ furrows, the de-exined pollen is an interesting experimental system for studying pollen germination. This report focuses on the microscopic and ultrastructural changes in the aspects of polarization, predetermination of the germination site and new wall synthesis during the course of isolation and germination of the de-exined pollen. It was shown that the de-exined pollen was already in an active state and had established its polarity and germination sites prior to exine detachment. The germination sites were still localized at the region of the previous germ furrows even after exine detachment. The new wall deposited at the germination sites appeared to have an important morphogenetic role in setting a limit to the size of pollen tube diameter . These results support our assumption that the de-exined pollen may have an extensive application in the research of pollen biology.
基金The National Basic Research Program(973 Program)of China under contract No.2010CB951203the National Natural Science Foundation of China under contract Nos 41206057,41576067,41376075 and 41576061
文摘Mangrove degradation must reduce carbon sequestration in recent years, thereby aggravating global warming.Thus, short-term impacts of human activity on mangrove ecosystems are cause for concern from local governments and scientists. Mangroves sediments can provide detailed records of mangrove species variation in the last one hundred years, based on detailed 210 Pb data. The study traced the history of mangrove development and its response to environmental change over the last 140 years in two mangrove swamps of Guangxi, Southwest China. Average sedimentation rates were calculated to be 0.48 cm/a and 0.56 cm/a in the Yingluo Bay and the Maowei Sea, respectively. Chemical indicators（δ13Corg and C：N） were utilized to trace the contribution of mangrove-derived organic matter（MOM） using a ternary mixing model. Simultaneous use of mangrove pollen can help to supplement some of these limitations in diagenetic/overlap of isotopic signatures. We found that vertical distribution of MOM was consistent with mangrove pollen, which could provide similar information for tracing mangrove ecosystems. Therefore, mangrove development was reconstructed and divided into three stages： flourishing, degradation and re-flourishing/re-degradation period. The significant degradation, found in the period of 1968–1998 and 1907–2007 in the Yingluo Bay and the Maowei Sea, respectively, corresponding to a rapid increase of reclamation area and seawall length, rather than climate change as recorded in the region.
