Comparison of Embryonic Gene Expression Levels in Dairy Heifers and Mature Cows.
Bibliographic record
Abstract
The modern high producing, lactating dairy cow in North America is sub fertile and the reasons for the decline in fertility are multifactorial. Even though the pregnancy rate of lactating dairy cows reduced drastically from 66% to 30% over the decades it remained unaltered or even slightly increased (70%) in heifers. Low pregnancy rates in cows could be due to an array of causes, and reduced embryo quality is one important factor among them. Embryo quality is the ability of the growing embryo to continue development in order to establish pregnancy and to produce a calf. Embryonic genome activation, compaction and cavitation, elongation of the trophoblast, secretion of interferon tau, differentiation of placental tissues, and development of the inner cell mass into the fetus are important events in the embryonic development. In order to compare the quality of the embryos, levels of gene expression of selected developmentally important genes [Na/K-ATPase, facilitative glucose transporters (GLUT5), interferon tau (IFNô), heat shock protein (HSP) and apoptotic genes (BCL2, Bax)] of mature cows and heifers were studied. Preliminary study was performed to optimize the PCR conditions of above genes using in vitro produced early stage bovine embryos. Good quality morula stage embryos were collected from super ovulated 2nd/ 3rd parity cows and heifers. From both groups (5 embryos each) total RNA was extracted using PicoPure RNA isolation kit (Arcturus). After reverse transcription of total RNA using Cells-to cDNA II kit, PCR was performed using JumpStart RED Taq Ready Mix PCR reaction mix and gene specific primers. PCR products were analysed by gel electrophoresis using ethidium bromide (0.2μg/ml) stained 2% agarose gel and photographed under ultraviolet illumination. The relative optical density of each gene was normalized to house keeping gene (Glyceraldehyde-3-phosphate dehydrogenase: G3PDH) and compared between cows and heifers. Expression levels of HSP and INFô were higher in mature cows than heifers, whereas the expression of GLUT5 and Na/K ATPase were slightly increased in heifers compared to cows. The anti apoptotic gene BCL2 was highly expressed in heifer embryos. These findings tend to suggest that the differential expression of above genes may result in poor quality embryos and thereby reduced pregnancy rates in mature cows. More studies are needed to be performed in order to conclude, whether the differences in the expression of developmentally important genes in embryos of mature cows, play a role in reduced pregnancy rates.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".