Homework / test English to Spanish Medical Medical: Pharmaceuticals

Buenos días, tengo que hacer la traducción de los párrafos que copio a continuación. En ellos aparece "sub-strain" strain=cepa tengo entendido, no he visto hasta ahora substrain pero podría ser como "cepa secundaria",,.... GRacias


Abstract
C57BL/6J and C57BL/6N inbred mice are widely, and often interchangeably, used for stem cell research; yet, these substrains harbor discrete genetic differences that can cause phenotypic disparities. In this issue of Stem Cell Reports, Morales-Hernández et al. identify one particular difference—disruption of Nicotinamide Nucleotide Transhydrogenase (Nnt)—that increases reactive oxygen exposure and impairs hematopoietic progenitor cell function in C57BL/6J, as compared to C57BL/6N, mice.


Main Text
The laboratory mouse has been a highly valuable tool for biological and biomedical research, and the inbred C57BL/6 strain is one of the most widely used across the globe, thanks in part to its fecundity, lifespan, and relatively low predisposition to spontaneous tumors. The origins of the C57BL/6 strain date back to the early 20th century, when Miss Abbie Lathrop began breeding mice on her farm in Granby, Massachusetts. It was there that Lathrop established and maintained several colonies of mice, some of which she later sold to the Harvard geneticist William Castle. In 1921, Castle’s student, C.C. Little (who later went on to found the Jackson Laboratory), crossed female mouse 57 to male mouse 52 from Lathrop’s stocks to generate progeny termed C57 Black (C57BL). Little continued propagating these mice until he established the C57BL/6J substrain at the Jackson Laboratory in 1948. In 1951, a colony of C57BL/6J mice was transferred to the National Institutes of Health (NIH), establishing the C57BL/6N substrain, which was later distributed to several companies including Charles River Laboratories (C57BL/6NCrl), Harlan Sprague Dawley (C57BL/6NHsd), and Taconic Farms (C57BL/6NTac).