Figure 1.

Figure 2.
![Ultrastructure of parotid glands of flight mice. Panel A, STS-135: Acinar cells have basally located nuclei [N (binucleate cells are common)], a prominent Golgi complex (G), and abundant apically located secretory granules (SG). Intercellular canaliculus (IC). Scale bar = 2 μm. Panel B, STS-135: Intercalated duct. The duct cells have apical vacuoles (arrows) containing material endocytosed from the lumen (L). Scale bar = 2 μm. The inset shows a similar vacuole in a striated duct cell immunogold labeled for PSP, an acinar secretory protein. Scale bar = 0.5 μm. Panel C, Bion-M1: A recently formed autophagic vacuole (AV1) containing secretory proteins labeled for PSP is present in an acinar cell. An older autophagic vacuole (AV2) contains remnants of secretory granules and other organelles, but shows little labeling. Secretory granule (SG); nucleus (N). Scale bar = 1 μm. Panel D, Bion-M1: Apoptotic acinar cells (Apop) phagocytosed by a macrophage (arrowheads). Myoepithelial cell (MEC). Scale bar = 2 μm.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6471e20b215d2f6c89db3eea/j_gsr-2015-0001_fig2.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKL3MB22LX%2F20251216%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251216T024647Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEI7%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaDGV1LWNlbnRyYWwtMSJHMEUCIQD8WGxrtNfxZu341od%2FsrGm2xG09JV8s6kBxqoXRpgVeQIgGPJvgetUZdmHU6WDi0dh3rNFOObwwbg%2FMKtadkbT%2Fa8qvAUIVxACGgw5NjMxMzQyODk5NDAiDCH2FLfB1suC370JsSqZBZ4DC6trXGvrfBw%2F%2BgeXfHZp5xwREribyX59OGZ5B64IJ0SmFeBGrD4yVmxttUZ%2B2mxgCq9HRzkRhPop5Uap2hvjSG4Cgl3dL0j0cjb6rJrOITiEY6BVhNXEYXe7LX7%2FD7lKb4cdfbSBwIysc5AjlaVyPoTCcBX1bzTnXvE1XGwK4LgiQzyEY1LUEbE12pC4dS1UczR37Izw8aCsR0U7aBWAEe0jOSz2uQrxCXAH5HjEmeYE08nZu79e%2FePalAlVboM1hQeK4tIczRocvkkEpHtOGw8S5ZF7jOWTC2XKIC6yrSf4KVpeeyMqUN%2BSqvu70pgbXip%2BK20UF0ftw%2FPFh87E1qfGE5p3tuVHiZil7hQymx3vSXBSrYydXAmG8g5b%2Bs2XO4fQirIx%2FQza5wJTN2us8emMg9wgCiuV3ZgmYnjvujKvS2q%2B5xgjKTh0MGkwTs1hB7fN5CJXF7JVzy5xacTnI7hOu%2B2HZE10TAQfWBMUrJcSoVF2WmvhAKvTSWolwa7nw6lUwVMSjb50mPTIjBOT51gJysa9sFn%2BwLNBAyCSheUE4zCwIyc9fWuskxzsMDR7yEZg%2B7Ue4AhvZq3QWhBj2wEXxuL6mPN2zWs73nFcb8MOdKq6G840831S9FQ6GcnIQRBt%2ByJtYUeTd2ZBoGnpoik%2Ff6N0YdWc2gPFoKFlj6relz80CkznfXxH3UQk67qkA6KUgktMs8Pw7cZSh8Q%2B9SNWScQmM7Y6rqUZC2%2FZRhrkQ4yPn42tNYc%2F6cYnCkXFSyRueBJLlDWOSvEtA0hngLaGYAxgMpLfL23pixqC74vsXL5IFdN3yPfhV1nGn2snpeWvJwFtUpb%2FkEfo9je3xvjvAoUOcP3zs6MaFPUqfmISNPisOS69MO2NgsoGOrEBayWCTRAtyfQ15vXUhCeN875%2FPDb4DZ2yIIA9kvxf8WNL4lSqbmcioA0elRdKNSTJdnOLhKXu3eCg04DsOF6YKxB0F4C8jt8GGPwq82bBL4FTJrWFaUc%2FgUR1l%2BDRL8EJXU0oZxlyc5yawHKSBtIGkmCrKxpoA8sn33JN%2FiXBWaMQBA3Dqor6nQ%2FmC0XrdrB0%2FQK49JVOagybqOxn8VwgdoxOqju4HwdGQ15LcsyKoynd&X-Amz-Signature=b554a3f8b0718017e4043a3d8ca4d31afa6b8ce8bd749f24558272082528693c&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Ratios of RII to Total Protein of STS-135 and Bion-M1 PAGE_
| F | C1 | C2 | ||
|---|---|---|---|---|
| STS-135 | PAGE | 70.8 | 69.28 | 69.99 |
| RII | 5.16 | 41.43 | 24.24 | |
| Ratio | 0.073 | 0.60 | 0.35 | |
| Bion-M1 | PAGE | 153.6 | 129.0 | --- |
| RII | 21.7 | 16.26 | --- | |
| Ratio | 0.14 | 0.13 | --- |
Quantitative Immunogold Labeling of STS-135 and Bion-M1 Salivary Glands (Gold Particles/µm 2 ± SEM)_
| Bion-M1 | Flight | Habitat |
|---|---|---|
| Amylase | 15.3 ± 1.11∞ | 10.3 ± 0.69 |
| RII | 10.1 ± 0.47 | 11.3 ± 0.49 |
| PSP | 37.4 ± 1.17§ | 30.6 ± 1.76 |
| PRP | 22.5 ± 1.61 | 24.8 ± 2.08 |
| DCPP | 23.1 ± 0.95 | 25.2 ± 1.27 |
Microarray Analyses of Secretory Protein Gene Expression_
| STS-135 | Bion-M1 | |||
|---|---|---|---|---|
| Gene a | Log2 F/Hb | Fold Change F/H | Log2 F/H | Fold Change F/H |
| Amy1 | 0.030 | 1.02 | 0.169* | 1.124 |
| Bpifa2 | 0.241§ | 1.18 | 0.170* | 1.13 |
| Lpo | 0.070 | 1.05 | 0.160* | 1.18 |
| Lyz1 | 0.317 | 1.25 | 0.898∞ | 1.86 |
| Pip | 0.228* | 1.17 | 0.169* | 1.13 |
| Prpmp5 | -0.161§ | 0.894 | -0.861∞ | 0.550 |
Body Weights of STS-135 and Bion-M1 Mice_
| Group | Initial Body Wt. (g) ± SEM (n) | Final Body Wt. (g) ± SEM (n) |
|---|---|---|
| STS-135 | ||
| Flight | 20.7 ± 0.40 (7) | 18.4 ± 0.52 (7) |
| AEM Ground Control | 20.7 ± 0.31 (15) | 19.4 ± 0.33 (15) |
| Vivarium Ground Control | --- | 19.7 ± 0.34 (15) |
| Bion-M1 | ||
| Flight | 26.8 ± 0.55 (6) | 29.4 ± 1.73 (6) |
| Synchronous Vivarium Ground Control | 29.2 ± 0.44 (8) | 28.7 ± 0.30 (8) |
| Asynchronous Habitat Ground Control | 27.3 ± 1.15 (7) | 29.7 ± 0.83 (7) |
| Asynchronous Vivarium Ground Control | 26.7 ± 0.78 (7) | 28.9 ± 1.03 (7) |