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Harfe, B. D.

Publications and source records attributed to Harfe, B. D..

2 recordsLinked to original sources

Design, construction, and advantages of 100% online laboratories in an upper division undergraduate biology course

For centuries, students have been taught by passively listening to lectures, usually in large groups. In many fields, this type of course delivery is not ideal. In addition, students that have grown up with online access and/or have been forced to take online course during the recent pandemic, are seeking improved online educational experiences. As providers of education, Universities must adapt to this rapidly changing environment. The emergence of exciting, "disruptive" technologies has provided the tools needed for educators to revolutionize the delivery of higher education. The University of Florida, through UF Online, provides students the opportunity to enroll in fully online four-year undergraduate degrees. In this report, we describe the development of fully online laboratories for the upper-division course Evolutionary Developmental Biology, which fulfill the University of Floridas laboratory requirement. This course is taken by Biology, Zoology, and related majors, including majors in the 100% online Biology degree. The experiments in the virtual laboratories would have been impossible to teach in a residential setting due to time constraints, cost, student safety issues, and regulatory/certification requirements. The ability to perform these experiments online provided University of Florida undergraduates located throughout the world access to unique, one-of-a-kind laboratory experiences. The virtual laboratories allowed students to undertake in-depth exploration and application of course content that is not possible in a residential setting. Completion of the Evolutionary Developmental Biology course provided undergraduate students the opportunity to obtain a science degree without ever visiting the universitys residential campus. During the Fall 2020 term, this course was made available to residential students, thus allowing this cohort of students to continue to make progress, 100% online, towards their undergraduate degree during the COVID19 pandemic.

developmental biology↗

Sonic Hedgehog is not a limb morphogen but acts as a trigger to specify all digits.

Limb patterning by Sonic hedgehog (Shh) has served as a paradigm of "morphogen" function, acting either by graded spatial or temporal signal integration. Yet how Shh instructs distinct digit identities remains controversial. Here, we bypassed the requirement for Shh in cell survival during limb bud outgrowth and demonstrate that a transient, early Shh pulse is both necessary and sufficient for normal limb development. Our analysis of Shh-responding cells shows signaling acts at only short-range during this time window and that Shh patterns digits indirectly, via a relay mechanism, rather than by direct spatial or temporal signal integration. Using a genetic assay for relay signaling, we unexpectedly discovered Shh also specifies digit 1 (the thumb; previously thought to be exclusively Shh-independent) indirectly, thus implicating Shh in a unique regulatory hierarchy for digit 1 evolutionary adaptations, such as opposable thumbs. This study illuminates Shh as a trigger for a relay network that becomes rapidly self-sustaining, with mechanistic relevance for limb development, regeneration, and evolution.

developmental biology↗