Comments on abstract, title, references

1.Obviously, the aim of this paper was to research whether the virus could induce a defense mechanism in Marine diatom spores.

2.The study found that there is a possible mechanistic link between viral infection, bloom termination, and mass carbon export events . In this paper, they investigated and quantified the dynamics of spore formation during viral infection of the marine planktonic diatom Chaetoceros socialis. These are all clear.

3.As for title, it is also closely informative and relevant.

4.The references are relevant, correct, and include appropriate key studies. But there is a little problem that there are some outdated references like "Cottrell MT, Suttle CA. 1995", "Guillard RRL. 1975", "Klee AJ. 1993" and so on.

Comments on introduction/background

1.It is clear we are already known:

a. the range of conditions in which a species can survive or act as a defense strategy against predators and/or pathogens can be increased by heteromorphic life cycles such as resting cysts, spores, or akinetes.

b. In diatoms, resting spores play an important role in community structure and population dynamics, acting as ‘seed banks’ and allowing species to subsist under sub-optimal conditions until more favorable environments return.

c. viruses have historically been considered to mediate the recycling of particulate organic matter through lysis of their host – a process referred to as the ‘viral shunt’.

d. viruses may also act as ‘shuttles’ of carbon to depth.

2.I think the research question is not outlined clearly, because they only say that they investigated and quantified the dynamics of spore formation during viral infection of the marine planktonic diatom Chaetoceros socialis using two host strains isolated from geographically distinct regions (Italy and Japan)

3.the research question is justified given what is already known about the topic. Because Infection by viruses as a trigger for resting spore formation has not been extensively explored and the possibility does exist.

Comments on methodology

1.The subject is is very consistent with the purpose of this paper and very representative. A little question is there is no table to express the subject.

Concluding:

Chaetoceros socialis strain APC12 was isolated in 2015 from a single short chain of cells that had germinated during incubation of surface sediments collected in the Gulf of Naples (Mediterranean Sea, Italy);

Strain L-4 (identified as C. socialis f. radians) was isolated in 2005 from Hiroshima Bay, Japan and kindly provided by Yuji Tomaru (National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency);

The virus used in this study was CsfrRNAV01, a single-stranded RNA virus recently reclassified into the genus Bacillarnavirus and documented to specifically infect strain L-4.

2.the variables defined and measured are all appropriate.

3.The methods they use are similar to those of other scholars, but with reasonable adjustments according to their own circumstances. Therefore, the study methods are valid and reliable.

4.Their all experiments were carried out in triplicate at 18°C and the details are very good. Absolutely, we can replicate this study if we do it right.

Comments on data and results

1.The way of the data presented is appropriate:

a.Tables and figures are relevant and clearly presented.

b.Units, rounding, and number of decimals are appropriate.

c.Titles, columns, and rows are labelled correctly and clearly.

2.The text in the results add to the data is repetitive.

3.Statistical significance is a mathematical tool that is used to determine whether the outcome of an experiment is the result of a relationship between specific factors or merely the result of chance. For example, in this paper, The drop in cell abundance during virus infection of APC12 was concurrent with a notable increase in spore formation compared to the uninfected control (P=0.006).

4.Practically meaningful result is used to apply and produce practical benefits. The results of this paper can be applied to the prevention and treatment of red tide.

Comments on discussion and conclusions

1.The results were discussed from the perspectives of regional restriction, inter-specificity, biological stressors, and gene level. And they placed into context without being over interpreted.

2.The conclusions answered the aims of the study.

3.There are many references or results to support the conclusions. For example, Virus infection also triggers the appearance of resistant, diploid or aneuploid morphotypes of E. huxleyi with lower growth rates than uninfected controls (Frada et al., 2017), an observation that is consistent with their findings of lower growth rates for C. socialis cells germinated from infected spores (Fig. 4c).

4.The limitations of the study are opportunities to inform future research. For example, although the sub cellular mechanisms that regulate the induction of resting spores by viral attack remain to be clarified, their findings add to the ecophysiological and evolutionary arms race that governs host–virus interactions in the oceans.