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  • 2020-2022  (2)
  • 1
    Publication Date: 2021-10-15
    Description: Millennial-scale reductions in monsoon precipitation, so-called Weak Monsoon Intervals (WMIs), have been identified in numerous paleoclimate records across the Afro-Asian monsoon domain throughout the last glacial-interglacial cycle. These are considered the regional response to cooling during Heinrich events in the North Atlantic realm and several mechanisms have been suggested to explain this hemisphere-scale climatic teleconnection. In particular, reductions in Indian Ocean sea surface temperature (SST) have been proposed as the linking element between Heinrich events and WMIs. However, the validity of this relationship has only been demonstrated for the last ~20 kyr, leaving unresolved whether it also holds on longer time scales. Here we present a new paired record of planktonic foraminifera-based δ18Osw-ivc and UK'37-based SST from the northern Bay of Bengal, covering the last ~130 kyr. The δ18Osw-ivc record clearly reflects orbitally paced changes of Indian Summer Monsoon intensity superimposed by centennial- to millennial-scale WMIs that occurred synchronously to North Atlantic Heinrich events. Comparison with the UK'37-based SST reconstruction reveals, however, that WMIs in most cases were not paralleled by ocean surface cooling, questioning whether Indian Ocean SST lowering was the linking element between Heinrich events and reductions in monsoon precipitation in Asia also during the last glacial period.
    Keywords: 551 ; Indian Summer Monsoon ; Weak Monsoon Intervals ; marine sediments ; Bay of Bengal ; foraminifera oxygen isotopes ; UK'37 sea surface temperature
    Language: English
    Type: map
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  • 2
    Publication Date: 2021-12-14
    Description: Prymnesium parvum is a bloom forming haptophyte that has been responsible for numerous fish kill events across the world. The toxicity of P. parvum has been attributed to the production of large polyketide compounds, collectively called prymnesins, which based on their structure can be divided into A-, B- and C-type. The polyketide chemical nature of prymnesins indicates the potential involvement of polyketide synthases (PKSs) in their biosynthesis. However, little is known about the presence of PKSs in P. parvum as well as the potential molecular trade-offs of toxin biosynthesis. In the current study, we generated and analyzed the transcriptomes of nine P. parvum strains that produce different toxin types and have various cellular toxin contents. Numerous type I PKSs, ranging from 37 to 109, were found among the strains. Larger modular type I PKSs were mainly retrieved from strains with high cellular toxin levels and eight consensus transcripts were present in all nine strains. Gene expression variance analysis revealed potential molecular trade-offs associated with cellular toxin quantity, showing that basic metabolic processes seem to correlate negatively with cellular toxin content. These findings point towards the presence of metabolic costs for maintaining high cellular toxin quantity. The detailed analysis of PKSs in P. parvum is the first step towards better understanding the molecular basis of the biosynthesis of prymnesins and contributes to the development of molecular tools for efficient monitoring of future blooms.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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