Development of taxonomic rRNA-targeted probes of two harmful algae: Prorocentrum minimum and Karenia mikimotoi by fluorescence in situ hybridization

Harmful algal blooms recently have been under the spotlight throughout the world, because of their nega- tive impact on the marine environment, aquaculture, fisheries as well as public health. The development of methods for rapid and precise identification and quantification of causative species is essential for the warning and monitoring of blooms, among which the techniques based on taxonomic probes are the most favored. In this study, two harmful algae, i.e., Prorocentrum minimum and Karenia mikimotoi were tak- en into consideration. The partial large subunit rDNA （D1-D2） of both species were firstly PCR-amplified, cloned and sequenced. The obtained sequences were then introduced to carry out alignment analysis for gene specific regions. Three respective candidate probes for each species were designed and used to screen the optimal probe by performing fluorescence in situ hybridization （FISH） tests. The results showed that the probes Pmin0443 and Kmik0602 displayed the best hybridization for P. minimum and K.. mikimotoi, respectively. Both the specific （taxonomic） （Pmin0443 and Kmik0602） and the control probes （UniC0512 and UniR0499） were used for cross-reactivity tests with other microalgae in our laboratory. The probes Pmin0443 and Kmik0602 are specific and could be served as taxonomic probes introduced into the tech- niques targeting rRNA, such as FISH, sandwich hybridization, and DNA-microarray assay of P minimum and K. mikimotoi in the future. Finally, FISH analyses with both probes were performed on the simulated field samples. The probes could hybridize exclusively with the target cells well, and no significant differ- ence （p 〉0.05） was observed in the cell densities of the samples determined by FISH and light microscopy （LM）. All suggest that the probes are specific and could be introduced into FISH for the monitoring of both harmful algae.

东海原甲藻藻华和台湾暖流种源关系的进一步研究

近20 a来,东海近岸海域频繁爆发了大规模的东海原甲藻藻华,造成了该海域生态系统的严重失衡。2013年前的调查研究显示东海原甲藻藻华发源于台湾暖流锋面,随台湾暖流锋面入侵近海而发展扩大,但受调查范围限制未能明确该藻华最早发生位置。本研究往南扩展了调查断面,于2013年春、夏季,在24°N^30°N海域进行了4次大面调查。结果显示东海原甲藻藻华最早发生于台湾海峡北端,且随台湾暖流锋面推进向北及近岸扩展。这不仅再次证实了台湾暖流锋面为东海原甲藻藻华的发生提供种源,而且明确了在东海区域东海原甲藻藻华最初发生的位置。这为该藻华的监控提供了重要的科学依据,为其他类似藻华的发生、发展提供了参考。

First observation of Karlodinium venef icum from the East China Sea and the coastal waters of Germany

Harmful algal blooms often occurred in the East China Sea （ECS） and the German coastal waters of the North Sea but Karlodinium veneficum had not been taxonomically reported. Two strains of Karlodinium （LAMB090611 and LAMB010601） were isolated from the two areas in 2009. The morphological characteristics and molecular phylogeny of two strains are compared on the basis of observation of a light microscope, a scanning electron microscope （SEM）, a laser scanning micro-scope （LSM） and an internal transcribed spacer （ITS） sequence data. The mean cell length of strain LAMB090611 is （14.2 ± 1.8） μm （range 11.1–18.7 μm） and mean width is （10.8 ± 1.5） μm （range 8.2– 14.7 μm）. The mean cell length of strain LAMB010601 is （15.1 ± 1.2） μm （range 12.7–17.9 μm） and the mean width is （11.4 ± 1.1） μm （range 9.1–14.7 μm）, respectively. The two strains are similar in morphological characteristics, including a straight apical groove, distinct ventral pore, sulcal extension, cingulum displacement, two or four irregular shaped chloroplasts within the cell and almost equal sized epicone and hypocone. The large and round nucleus is located at the center or at the hypocone of the cell. The sequence length of the ECS strain LAMB090611 and the German strain LAMB010601 is 640 and 646 bp, respectively. The GC content is 49%. The nucleotide similarity of the two strains is 98.1%. The sequence divergence is 0.003. Both strains are confirmed as Karlo-dinium veneficum （D. Ballantine） J. Larsen and this is the first taxonomic report from China and Germany coastal waters. The population dynamics of this toxic species in the ECS and German coastal waters needs to be investigated in the near future.

Biomarker records in penguin droppings and observed changes in penguin communities and their response to the ENSO in the Western Antarctic

Lipid biomarkers in AD2 penguin droppings-amend soil core from the Ardley Island,Western Antarctic,were dated using 210Pb.Changes in the fatty acid ratios of nC18:2/nC18:0 from the penguin droppings reflect climate changes coincident with ENNO events during 1931-2006.The occurrence of the minimum values in the depth of 2-3 and 6-7 cm are consistent with the end of ENSO in 1958 and 1983,respectively,reflecting a lag of the biomarker records in AD2 penguin droppings-amend soil in climatic signatures.This study also reveals that the changes in the relative concentration of n-alkanes nC23,the ratios of nC23/nC17 and nC21 /nC22+,and carbon preferential index(CPI) values collectively indicate the variations of soil microor-ganism and lower plant,which are closely related to climate changes.The ratios of bacterial fatty acids iC15:0/aC15:0 reflect the increasing significance of microorganism activities during the two periods that occurred at the end years of ENSO.Decrease in CPIA value and increase in nC21 /nC22+ indicate that low molecular weight fatty acids are derived from microorganism;and their insignificant correlation with Pr/Ph suggests microorganisms play an important role in the relatively simply ecosystem in the Antarctic and are closely linked to climatic conditions.In addition,the observed penguin community indicates the popula-tion of penguin can largely reflect the impacts of global climate changes on the ecosystem.