Complex sentence: The journal has developed standards for the publication of mouse mutant studies, which often are fatally flawed, causing a waste of time, effort, and research resources, and leading to ethical problems because of the unnecessary use of live animals for flawed studies.
Split into simpler sentences: The journal has developed standards for the publication of mouse mutant studies. Many mouse mutant studies have serious methodological problems leading to fatally flawed scientific conclusions, causing a waste of time, effort, and research resources, and leading to ethical problems because of the unnecessary use of live animals for flawed studies.