GIANT PANDA SPERM TOLERATE CRYOPRESERVATION AT RAPID FREEZING AND THAWING RATES
Bibliographic record
Abstract
Many individuals in the ex situ giant panda (Ailuropoda melanoleuca) population do not reproduce, largely due to behavioral deficiencies. Artificial insemination is an important assisted breeding tool for genetically managing this species. To optimize sperm cryopreservation, this study compared three cryomethods and three thawing temperatures. Ejaculates (n = 28) from five adult (5.5 to 20.5 y) giant pandas were assessed for sperm traits, diluted in a TEST egg-yolk diluent containing 3.3% glycerol, cooled slowly to 5°C over 4 h, loaded in 0.25 ml straws and cryopreserved using a (1) manual two-step method, (2) automated Cryomed and (3) field-ready dry shipper. For the two-step method, samples were placed 7.5 cm above liquid nitrogen for 1 min (− 35°C/min), then 2.5 cm above liquid nitrogen for 1 min (− 100°C/min) before plunging. Using a programmable freezer (Forma Cryomed), sperm were frozen at − 40°C/min, then −100°C/min. For the field-ready method, samples were placed directly into a dry shipper for 10 min (− 35°C/min). Samples were thawed in a waterbath at (1) 22°C for 30 sec, (2) 37°C for 30 sec or (3) 50°C for 10 sec. Each aliquot then was diluted in Ham's F10 culture medium at 37°C and incubated for 24 h. Samples were assessed for sperm motility (0–100%), forward progression (scale, 0–5; 5 is best), intact acrosomes (0–100%) and longevity quotient (initial motility ÷ absolute gradient of motility decline over 24 h). Mean (± SEM) fresh ejaculate traits were: sperm motility, 83.2 ± 1.3%; forward progression, 4.0 ± 0.1; and intact acrosomes, 86.4 ± 1.4%. Cryomethod influenced (P < 0.05) giant panda sperm quality. Post-thaw sperm motility was similar (P > 0.05) among the two-step (65.7 ± 2.0%), dry shipper (61.1 ± 2.3%) and Cryomed (58.5 ± 2.4%). Sperm progression post-thaw also did not differ (P>0.05) among cryomethods (range, 3.0 to 3.3). Post-thaw intact acrosomes were highest (P < 0.05) in the two-step (53.0 ± 2.1%) and dry shipper (50.6 ± 2.4%) compared to the Cryomed (44.2 ± 2.5%). The longevity quotient was higher (P < 0.05) in the dry shipper (25.8 ± 3.1) than the Cryomed (16.7 ± 1.5), and both were similar (P > 0.05) to the two-step (21.5 ± 1.5). Thawing temperature also influenced (P < 0.05) giant panda sperm quality. Post-thaw sperm motility was higher (P < 0.05) when thawed at 50°C (67.5 ± 2.2%) compared to 22°C (56.7 ± 2.2%), and both were similar (P > 0.05) to 37°C (62.7 ± 2.2%). Sperm progression post-thaw was better (P < 0.05) in samples thawed at 50°C (3.4 ± 0.1) compared to 37°C (3.0 ± 0.1) or 22°C (3.0 ± 0.1). Thawing temperature had no influence (P > 0.05) on intact sperm acrosomes (range, 47.6% to 51.9%) or longevity quotients (range, 16.8 to 23.6). These data illustrate that optimal post thaw sperm quality in the giant panda is achieved with the manual two-step or dry shipper technique using a 50°C thawing temperature. This demonstrates that giant panda sperm can tolerate a rapid freezing rate (−35 to −100°C/min) in conjunction with a high thawing temperature (50°C). This finding suggests the possibility of successfully cryopreserving giant panda sperm in the field using the simple dry shipper technique. (Supported by the Morris Animal Foundation and the Friends of the National Zoo). (poster)
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".