Cloning and analysis of the cDNA encoding the horse and donkey luteinizing hormone beta-subunits.

This study explores the genetic coding of the beta-subunit of luteinizing hormone (LH) in horses and donkeys, and its relations to equine chorionic gonadotropin (CG) beta-subunits. The findings suggest both horse and donkey LH beta-subunit sequences share a high similarity, implying a strong evolutionary link, and understanding these could shed light on the unique receptor-binding properties of equine LH and CG.

Background

• The research paper boasts its insights on cloning and examination of the cDNA that encodes the horse and donkey luteinizing hormone (LH) beta subunits. LH is a hormone that plays an essential role in the reproductive system, controlling ovulation in females and stimulating testes in males.

Method and Findings

• The LH beta-subunit transcripts’ coding regions from horse (Equus caballus) and donkey (E. asinus) were cloned from pituitary gland RNA. The purpose was to explore their relationships with the corresponding equine chorionic gonadotropin (CG) beta subunits and to further comprehend the distinct receptor-binding property of equine LH and CG.
• The results show that horse and donkey LH beta-subunit sequences bear a high resemblance with a 97% identity level on nucleotide (nt) and 93% on amino acid (aa). This finding confirms a strong evolutionary lineage between horses and donkeys, indicating that the C-terminal extension observed in both subunits had already occurred before these species diverged.
• Moreover, sequence comparisons and Southern blot analysis verified that the pituitary (LH) and placental (CG) beta subunits in donkeys, similar to horses, likely originated from one gene. This is contrasting to primates where the LH beta gene expressed in the pituitary is separate from the family of CG beta genes expressed in the placenta.
• The decoded amino acid sequences disclosed several variances among the horse and donkey LH/CG beta subunits that could contribute to their disparities in biological function. Furthermore, the research confirmed the presence of an extra Cys residue in the donkey subunit absent in other gonadotropin beta subunits.

Conclusion

• In conclusion, in-depth exploration and comparison of the LH beta subunit sequences of horses and donkeys shed light on their similar origin and distinct biosignatures, which might influence their unique receptor-binding characteristics. This research paves the way for further studies in understanding the intricacies of the reproductive system in equines.