Zichen Liu , Fazhi Xie , Liya Wang , Li Yu , Xiaoli Shi , Zhen Yang , Min Zhang
{"title":"Dolichospermum 的异囊分化对不同形式缺氮的反应","authors":"Zichen Liu , Fazhi Xie , Liya Wang , Li Yu , Xiaoli Shi , Zhen Yang , Min Zhang","doi":"10.1016/j.hal.2024.102742","DOIUrl":null,"url":null,"abstract":"<div><div>In recent years, initiatives aimed at mitigating eutrophication have successfully reduced nitrogen and phosphorus concentrations in numerous lakes across China. Notably, the management of total nitrogen levels has prompted a shift in the dominant genera responsible for harmful algal blooms. Among these, <em>Dolichospermum</em>, a typical diazotrophic cyanobacterium, exhibits the ability to differentiate heterocysts for atmospheric N<sub>2</sub> fixation under nitrogen-limited conditions. However, the underlying mechanisms driving heterocyst differentiation in response to the absence of specific nitrogen compounds remain poorly understood. This study analyzed the driving factors influencing heterocyst frequency using field data from Lake Chaohu collected between January and June 2022. Furthermore, an experiment was conducted utilizing NH<sub>4</sub>Cl, NaNO<sub>3</sub> and urea as nitrogen sources, with specific nitrogen deficiencies created to investigate the response mechanisms of <em>Dolichospermum</em> under these conditions. The results indicated significant monthly variations in heterocyst frequency in Lake Chaohu, which were associated with the interaction of multiple driving factors. Nutrient changes emerged as the most intuitive driving factor, with heterocyst frequency showing a significant negative correlation with total nitrogen and dissolved total nitrogen levels. Experimental results demonstrated that the absence of NO<sub>3</sub><img>N promoted both the biomass and heterocyst frequency of <em>Dolichospermum</em>. When NH<sub>4<img></sub>N was limited, the proliferation of <em>Dolichospermum</em> was inhibited, leading to an extended period of heterocyst development. Although a lack of urea eventually increased heterocyst frequency in <em>Dolichospermum</em>, there was no significant increase in biomass. The concentrations of the three nitrogen sources exhibited a negative correlation with heterocyst differentiation, with the effects of NO<sub>3</sub><img>N and urea deficiency on heterocyst differentiation being significantly stronger than those of NH<sub>4</sub><img>N. Moreover, heterocyst differentiation frequency was positively correlated with photosynthetic efficiency, which indicated that the acquisition and distribution of photosynthetic energy between heterocysts and vegetative cells also influence the differentiation process of heterocysts to some extent. The findings highlight the differing responses of heterocyst differentiation to various forms of nitrogen, emphasizing the importance of prioritizing NH<sub>4</sub><img>N removal in nutrient control. However, further research is needed to determine the key threshold concentrations of different nitrogen sources that trigger heterocyst differentiation.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102742"},"PeriodicalIF":5.5000,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Response of heterocyst differentiation of Dolichospermum to different forms of nitrogen deficiency\",\"authors\":\"Zichen Liu , Fazhi Xie , Liya Wang , Li Yu , Xiaoli Shi , Zhen Yang , Min Zhang\",\"doi\":\"10.1016/j.hal.2024.102742\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>In recent years, initiatives aimed at mitigating eutrophication have successfully reduced nitrogen and phosphorus concentrations in numerous lakes across China. Notably, the management of total nitrogen levels has prompted a shift in the dominant genera responsible for harmful algal blooms. Among these, <em>Dolichospermum</em>, a typical diazotrophic cyanobacterium, exhibits the ability to differentiate heterocysts for atmospheric N<sub>2</sub> fixation under nitrogen-limited conditions. However, the underlying mechanisms driving heterocyst differentiation in response to the absence of specific nitrogen compounds remain poorly understood. This study analyzed the driving factors influencing heterocyst frequency using field data from Lake Chaohu collected between January and June 2022. Furthermore, an experiment was conducted utilizing NH<sub>4</sub>Cl, NaNO<sub>3</sub> and urea as nitrogen sources, with specific nitrogen deficiencies created to investigate the response mechanisms of <em>Dolichospermum</em> under these conditions. The results indicated significant monthly variations in heterocyst frequency in Lake Chaohu, which were associated with the interaction of multiple driving factors. Nutrient changes emerged as the most intuitive driving factor, with heterocyst frequency showing a significant negative correlation with total nitrogen and dissolved total nitrogen levels. Experimental results demonstrated that the absence of NO<sub>3</sub><img>N promoted both the biomass and heterocyst frequency of <em>Dolichospermum</em>. When NH<sub>4<img></sub>N was limited, the proliferation of <em>Dolichospermum</em> was inhibited, leading to an extended period of heterocyst development. Although a lack of urea eventually increased heterocyst frequency in <em>Dolichospermum</em>, there was no significant increase in biomass. The concentrations of the three nitrogen sources exhibited a negative correlation with heterocyst differentiation, with the effects of NO<sub>3</sub><img>N and urea deficiency on heterocyst differentiation being significantly stronger than those of NH<sub>4</sub><img>N. Moreover, heterocyst differentiation frequency was positively correlated with photosynthetic efficiency, which indicated that the acquisition and distribution of photosynthetic energy between heterocysts and vegetative cells also influence the differentiation process of heterocysts to some extent. The findings highlight the differing responses of heterocyst differentiation to various forms of nitrogen, emphasizing the importance of prioritizing NH<sub>4</sub><img>N removal in nutrient control. However, further research is needed to determine the key threshold concentrations of different nitrogen sources that trigger heterocyst differentiation.</div></div>\",\"PeriodicalId\":12897,\"journal\":{\"name\":\"Harmful Algae\",\"volume\":\"139 \",\"pages\":\"Article 102742\"},\"PeriodicalIF\":5.5000,\"publicationDate\":\"2024-11-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Harmful Algae\",\"FirstCategoryId\":\"99\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1568988324001756\",\"RegionNum\":1,\"RegionCategory\":\"生物学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MARINE & FRESHWATER BIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Harmful Algae","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1568988324001756","RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MARINE & FRESHWATER BIOLOGY","Score":null,"Total":0}
Response of heterocyst differentiation of Dolichospermum to different forms of nitrogen deficiency
In recent years, initiatives aimed at mitigating eutrophication have successfully reduced nitrogen and phosphorus concentrations in numerous lakes across China. Notably, the management of total nitrogen levels has prompted a shift in the dominant genera responsible for harmful algal blooms. Among these, Dolichospermum, a typical diazotrophic cyanobacterium, exhibits the ability to differentiate heterocysts for atmospheric N2 fixation under nitrogen-limited conditions. However, the underlying mechanisms driving heterocyst differentiation in response to the absence of specific nitrogen compounds remain poorly understood. This study analyzed the driving factors influencing heterocyst frequency using field data from Lake Chaohu collected between January and June 2022. Furthermore, an experiment was conducted utilizing NH4Cl, NaNO3 and urea as nitrogen sources, with specific nitrogen deficiencies created to investigate the response mechanisms of Dolichospermum under these conditions. The results indicated significant monthly variations in heterocyst frequency in Lake Chaohu, which were associated with the interaction of multiple driving factors. Nutrient changes emerged as the most intuitive driving factor, with heterocyst frequency showing a significant negative correlation with total nitrogen and dissolved total nitrogen levels. Experimental results demonstrated that the absence of NO3N promoted both the biomass and heterocyst frequency of Dolichospermum. When NH4N was limited, the proliferation of Dolichospermum was inhibited, leading to an extended period of heterocyst development. Although a lack of urea eventually increased heterocyst frequency in Dolichospermum, there was no significant increase in biomass. The concentrations of the three nitrogen sources exhibited a negative correlation with heterocyst differentiation, with the effects of NO3N and urea deficiency on heterocyst differentiation being significantly stronger than those of NH4N. Moreover, heterocyst differentiation frequency was positively correlated with photosynthetic efficiency, which indicated that the acquisition and distribution of photosynthetic energy between heterocysts and vegetative cells also influence the differentiation process of heterocysts to some extent. The findings highlight the differing responses of heterocyst differentiation to various forms of nitrogen, emphasizing the importance of prioritizing NH4N removal in nutrient control. However, further research is needed to determine the key threshold concentrations of different nitrogen sources that trigger heterocyst differentiation.
期刊介绍:
This journal provides a forum to promote knowledge of harmful microalgae and macroalgae, including cyanobacteria, as well as monitoring, management and control of these organisms.