While determining the primary structures of several E. coli ribosomal proteins, he developed manual micro-methods for isolating peptides using two-dimensional separation on cellulose thin layer plates (instead of using a series of chromatography columns) followed by dansyl-Edman degradation.

[2] From 1977 to 1980, Brosius spent a postdoctoral fellowship supported by the Fogarty International Center in Harry F. Noller’s lab at the University of California, Santa Cruz.

[4] During his stay at UCSC Brosius met visiting professor Carl Woese, who incited his interest in evolutionary thought and the power of molecular phylogenetic analysis.

His second postdoctoral fellowship (1980–1982), supported by the Deutsche Forschungsgesellschaft, took him to the laboratory of Walter Gilbert, Nobel prize laureate in Chemistry (1980), at Harvard University.

[7][8] In 1982, Brosius established his own laboratory at Columbia University College of Physicians and Surgeons as assistant professor partially funded by the Alfred P. Sloan Foundation[9] and the Irma T. Hirschl Trust.

In the mid-nineties, he established a transgenic and gene targeting facility serving the entire campus and beyond by generating, for example, mouse models designed for the study of human genetic disorders.

[22][23][24] Encouraged by the stimulating findings surrounding BC1 RNA, in the mid-nineties he emphasized the significance of RNA coding genes in association with genome projects[25] and embarked on generating more cDNA libraries based on non-protein coding RNAs from mice and various model organisms, ringing in the era of RNomics,[26][27][28] A number of small nucleolar RNAs prevalently expressed in the brain as well as imprinted (only expressed by one parental chromosome) were discovered in mice and men.

[31] Earlier, Brosius and coworkers demonstrated that mice lacking the BC1 RNA gene had deficiencies in exploratory behaviour in the laboratory and under semi-natural conditions.

[42] A plethora of functions have been assigned to TEs, one example being the bewildering spectrum of tasks allocated to the evolutionarily young primate-specific Alu elements.