Systems and methods relate to transgenic organisms and their use as biosensors are described. In some embodiments, the systems and methods include a first population of transgenic organisms that includes a first constitutively expressed reporter gene, and a first transgene that includes a first inducible promoter from a response pathway gene, wherein the first inducible promoter is coupled to a first reporter gene. Other embodiments are described.

Described herein are compositions, methods, a system, and kits for detection of endocrine disruptor chemicals (EDCs) in samples, such as samples of water including but not limited to waste water treatment plant effluent, using a live-cell fluorescence-based nuclear translocation reporter system. Upon binding of a ligand to a fluorescent-labeled reporter protein, the protein (and therefore the fluorescence) is translocated in a ligand level-dependent manner from the cytoplasm to the nucleus of live mammalian cells; this translocation is detectable as diffuse (cytoplasmic) fluorescence converting to localized, brightly fluorescent nuclei. The described kits can be used to reliably detect very low levels of EDC contamination, including in high throughput analysis systems as described.

Systems and methods relate to transgenic organisms and their use as biosensors are described. In some embodiments, the systems and methods include a first population of transgenic organisms that includes a first constitutively expressed reporter gene, and a first transgene that includes a first inducible promoter from a response pathway gene, wherein the first inducible promoter is coupled to a first reporter gene. Other embodiments are described.

A cell composition composed of spermatogonial stem cells, Sertoli cells, Leydig cells and optionally peritubular cells, is provided, as is a culture composition, artificial testicular construct, hydrogel composition, and device containing the same. A method for using the device as a physiologically relevant in vitro model of human testicular function to screen compounds for pharmacological or toxicological activity is also provided.

UO.sub.2F.sub.2 biosensors, and related U-sensing and/or F-sensing genetic molecular components, genetic circuits, compositions, methods and systems are described, which in several embodiments can be used to detect and/or neutralize uranium and in particular bioavailable UO.sub.2F.sub.2.