The Beverton-Holt and Ricker functions are two distinct ecological descriptions of the link between a parental population size and subsequent offspring that may survive to become part of the fish stock. This report presents a model consisting of a system of ordinary differential equations (ODEs), which couples a pre-recruit stage with several adult stages. Elements of slow-fast dynamics capture...

Elaydi and Yakubu showed that a globally asymptotically stable(GAS) periodic orbit in an autonomous difference equation must in fact be a fixed point whenever the phase space is connected. In this paper we extend this result to periodic nonautonomous difference equations via the concept of skew-product dynamical systems. We show that for a k-periodic difference equation, if a periodic orbit of ...

The forelimbs and hindlimbs of vertebrates are bilaterally symmetric. The mechanisms that ensure symmetric limb formation are unknown but they can be disrupted in disease. In Holt-Oram Syndrome (HOS), caused by mutations in TBX5, affected individuals have left-biased upper/forelimb defects. We demonstrate a role for the transcription factor Tbx5 in ensuring the symmetric formation of the left a...

Tbx5(del/+) mice provide a model of human Holt-Oram syndrome. In this study, the cardiac functional phenotypes of this mouse model were investigated with 30-MHz ultrasound by comparing 12 Tbx5(del/+) mice with 12 wild-type littermates at 1, 2, 4, and 8 wk of age. Cardiac dimensions were measured with two-dimensional and M-mode imaging. The flow patterns in the left and right ventricular inflow ...

To cite: Naderi N, McCurdy MT, Reed RM. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2014203851 DESCRIPTION A man in his 50s had a history of a congenital atrial and ventricular septal defect requiring repair decades prior. He also had a history of heart block requiring pacemaker placement. During an evaluation for pacemaker battery replacement, he was noted to...

Mutations in the Tbx5 transcription factor cause heart septal defects found in human Holt-Oram Syndrome. The complete extent to which Tbx5 functions in heart development, however, has not been established. Here we show that, in Xenopus embryos, Tbx5 is expressed in the early heart field, posterior to the cardiac homeobox transcription factor, Nkx2.5. During morphogenesis, Tbx5 is expressed thro...