IDENTIFICATION OF NOVEL TRANSCRIPTS AND METABOLITES IN SPERMATOZOA OF MALNAD GIDDA
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Date
2019
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Publisher
ICAR-SRS-NDRI, KARNAL
Abstract
Breed variations in fertility have been reported in literature with comparatively lesser infertility in
zebu breeds as compared to other breeds. While the problem of infertility is comparatively higher in
crossbred males as compared to pure bred males, the reason for the same has not been elucidated
yet. We hypothesized that comparative analysis of molecular profile of spermatozoa from dwarf zebu
and crossbred bull might help in identification of possible alterations in spermatozoa of crossbred
bull. On the other hand, the possible molecular pathways associated with high fertility in dwarf could
also be identified. With this back drop, global transcriptomic and metabolomic profile of a dwarf zebu
(Malnad Gidda) and crossbred (HF crossbred) bull spermatozoa was carried out. A total of 15814
and 17324 transcripts were identified in dwarf zebu bull spermatozoa and crossbred bull
spermatozoa respectively, of which 521 transcripts were differentially expressed between dwarf zebu
bull and crossbred bull spermatozoa. Among the differentially expressed transcripts 156 were
upregulated while 365 were down regulated in dwarf zebu bull spermatozoa as compared to
crossbred bull spermatozoa. Olfactory transduction pathway was upregulated whereas Ribosomal
pathways, Oxidative phosphorylation and metabolic pathways were downregulated in dwarf zebu bull
spermatozoa. Metabolomics analysis of sperm and seminal plasma revealed 1372 and 1240
metabolites in dwarf zebu bull and crossbred bull spermatozoa, respectively of which 71 metabolites
were differentially expressed between dwarf zebu bull and crossbred bull spermatozoa respectively.
A total of 1002 and 990 metabolites were identified in dwarf zebu bull and crossbred bull seminal
plasma, respectively; of which 6 metabolites were downregulated in dwarf zebu bull spermatozoa as
compared to crossbred bull spermatozoa. A metabolite Nitroprusside was 2.6 fold higher whereas LCysteine
and Acetyl-CoA were 2.4 fold lower in dwarf zebu bull as compared to crossbred bull
spermatozoa whereas, Tetradecanoyl-CoA and Phosphotidylethanolamine were 3.5 and 3 fold lower
in dwarf zebu bull seminal plasma as compared to crossbred bull seminal plasma. It is concluded
that transcriptional abundance of genes associated with Olfactory transduction were significantly
higher in dwarf zebu bull spermatozoa as compared to crossbred bull spermatozoa. Expression of
transcripts involved in ribosome pathway and oxidative phosphorylation were significantly
upregulated in crossbred bull spermatozoa as compared to dwarf zebu bull spermatozoa. A total of
2 novel transcripts and 3 noncoding RNAs were identified in dwarf zebu bull spermatozoa. Taurine
and hypotaurine metabolism pathway were highly enriched and concentration of nitroprusside was
significantly higher in dwarf zebu bull spermatozoa as compared to crossbred bull spermatozoa.
These findings might help in understanding the reasons for high incidence of infertility/ subfertility in
crossbred bulls and to improve the quality of cryopreserved spermatozoa.