Mutations in these genes result in abnormal or failed development of polarization in the Drosophila embryo. Nusslein-Volhard's experiments in 1979 identified and characterized all mutant alleles that affected the dorsal-ventral axis. Genes affecting dorsal-ventral polarization fall into two categories:
Biological warfare (BW)âalso known as germ warfare âis the use of biological toxins or infectious agents such as bacteria, viruses, and fungi with the intent to kill or incapacitate humans, animals or plants as an act of war.
Trench warfare. Trench warfare, warfare in which opposing armed forces attack, counterattack, and defend from relatively permanent systems of trenches dug into the ground. The opposing systems of trenches are usually close to one another. Trench warfare is resorted to when the superior firepower of the defense compels the opposing forces to âdig inâ so extensively as to sacrifice their mobility in order to gain protection. 1  A trench system may begin simply as a collection of foxholes hastily dug by troops using their entrenching tools.