In April 2010, a paper surfaced questioning a well-established concept regarding the branched assembly of actin filaments in moving cells. However, before accepting the new theory published in Nature by Urban et al., YSM decided to critically analyze the circumstances around this recent publication and in doing so, we sought the opinion of Yale’s resident actin expert: Dr. Thomas Pollard.
Pollard is a professor of Molecular, Cellular, and Developmental Biology, and his lab researches the protein interactions involved with actin assembly, aiming to reconcile the biochemical experiments in the lab with observations of live cells. Actin is known to be involved in muscle contraction but has now also been implicated in a much wider range of processes like cytokinesis, chromosome structure, and membrane traffic. Pollard notes that because actin is the most abundant protein in most cells, whatever you study, you’ll eventually run into it.
When consulted on the new actin article, Pollard replied that it was flawed because the authors failed to recognize evidence in their own micrographs that favor rather than disprove the concepts they were challenging. The next question, then, is how the piece got published in the first place. Before being published in scientific journals, papers are subject to a peer review process.
Aside from having over 200 publications already subjected to peer review, Pollard has also seen thousands of papers as editor or reviewer for several journals. “In virtually every case,” he says, “the paper is improved dramatically by peer review because the reviewers ask the authors to think about things that maybe they hadn’t thought about themselves.” Generally, when researchers submit a paper to a journal, the editor first determines if the subject matter is suitable and then sends it to other experts in the same field. Based on validity, significance, and originality, the reviewers recommend acceptance, revision, or rejection of the work. The editors respond to the authors with feedback from the reviewers, whose identities are often kept anonymous, and the researchers can then revise their manuscripts and respond to comments.
One current problem in scientific journals is that the amount of quality work exceeds the amount of room in journals. Also, acceptance or rejection often comes down to subjective criteria like the “coolness” factor, as Pollard calls it. Another issue is whether or not reviewers should be compensated for their work. Being a reviewer requires much time and effort, to which Pollard can attest, although editors and reviewers mainly volunteer their time, because peer review is essential to the vitality of the scientific community.
Peer review, though, can only detect the difference between honest mistakes and misconduct to a certain extent. Reviewers can often identify plagiarism because they know other works on the subject but they often cannot detect purposeful falsification of data, especially if there is not much related previous research, because they have not done the experiment themselves. Fortunately, peer review is not the final say on the validity of an article. The advancement of knowledge depends on the entire scientific community with many scientists repeating an experiment to confirm or question the results.. Due to the high premium on quality and reliability in scientific research aided by peer review, thousands of high-quality scientific articles are produced every month.
With the limitations of the peer review system, the new actin article has been called a controversy. However, Pollard says, “There aren’t real controversies, just good and bad experiments…The most common sources of apparent controversies are problems with experimental design and quality of the data coupled with bad assumptions.” The authors here argued that the absence of actin filament branches in their electron micrographs invalidated previous work that clearly showed branches. Other researchers are currently trying to figure out if and how the branches were lost in the recent work, so the matter may be resolved within the year. The process of peer review of the new paper may be over, but the process of scrutiny by the scientific community is just beginning.