[Ca²⁺]_i flux and insulin release patterns show mouse-to-mouse imprinting.

<p>(A) [Ca²⁺]_i flux and insulin release traces from islets taken from three different mice (labeled accordingly). Displayed oscillation frequency averages are 9 min (Mouse 1), 4.5 min (Mouse 2), and 15 s (Mouse 6). Periods were calculated using local minimum values. Insulin oscillations from mouse 6 were faster than the measured temporal resolution (22 s) of the chip, causing under sampling of secretion dynamics. (B) Comparison of average [Ca²⁺]_i and insulin oscillation periods from each animal. Data sets are n≥6 islets and error bars are ±1 standard deviation. (C) Plot of average [Ca²⁺]_i versus insulin for each mouse. The linear relationship of data points suggests good agreement of oscillation frequencies (R² = 0.98; p<0.0001).</p

Effects of weight gain with age on imprinting.

<p>(A–B) Representative examples of islet [Ca²⁺]_i patterns in 11 mM glucose among lean mice weighing <30 g (A) and aged/large mice weighing >40 g (B). (C) Mean period of oscillations among 10 lean and 3 aged/large Swiss-Webster mice. Mean weight and mean period of islet [Ca²⁺]_i oscillations differed between groups (p<0.001).</p

Dispersed beta cells do not display frank imprinting.

<p>(A) Representative examples of oscillatory patterns from 3 individual beta cells (A) and 3 islets (B) taken from the same mouse (Mouse 8 as indicated by the box in C). (C–D) Mean period ± SEM from 12 sets of beta cells (C) and corresponding islets (D) from the same mouse. Beta cells displayed longer period and also a greater degree of variability in their periods as noted by the large standard deviations they exhibited compared to islets. A total of 137 beta cells and 109 islets were recorded among 12 mice. One-way ANOVA indicates differences among beta-cell periods (P<0.01) and substantial differences among islet periods (p<1.0e-25) from mouse to mouse. (E) Scatter plot showing the relationship between oscillatory periods of beta cells and islets among the 12 mice studied (R² = 0.39, p = 0.22).</p

Both inbred and outbred mice display islet imprinting.

<p>(A–B) Two representative C57BL/6J mice out of a group of 9 displayed very different [Ca²⁺]_i oscillation patterns. Three representative islets from Mouse 6 display slow oscillations (A, period: 3.9±0.2 minutes, n = 12 islets total) and three representative islets from Mouse 5 display fast oscillations (B, period: 0.9±0.6 minutes, n = 9 islets total). One trace shown in B (bottom) shows a clear ‘slow component’ that was representative of n = 4 islets from Mouse 5 (period: 5.4±0.1 minutes). (C–D) The variation in the period of [Ca²⁺]_i oscillations indicates distinct differences from mouse to mouse for the inbred B6 strain (C) and the outbred CD-1 strain (D), as shown by one-way ANOVA (p<1.0e-24). Boxes drawn around Mouse 6 and Mouse 5 in (C) are described above.</p