ANNOTATION OF HIGHLY ABUNDANT PREGNANCY ASSOCIATED GLYCOPROTEIN ISOFORMS IN BUFFALO AND DEVELOPMENT OF PAG BASED IMMUNOLOGICAL ASSAY FOR PREGNANCY DIAGNOSIS
Loading...
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ICAR-NDRI, KARNAL
Abstract
The early pregnancy diagnosis is the major challenge in the livestock sector. One of the
molecules that gives scope to diagnose pregnancy at early stages of gestation is PAGs
(pregnancy associated glycoproteins), as they are directly secreted from conceptus to
maternal circulation around 22 to 28 days after fertilization. Thus, PAGs serve as marker for
pregnancy diagnosis and early embryonic mortality. So far, 12 PAG isoforms and 61 variants
were found in buffaloes at mRNA level. But there is inadequate knowledge about PAG genes
in buffaloes and also, we do not know the source for existence of so many PAG variants at
mRNA level. Whether these variants come from single gene loci or have multiple genes or all
these variants are products of splicing mechanism is not known. In order to gain insight about
these conundrums, the PAG genes were annotated in buffalo by using latest genome
assembly of water buffalo. During the course of following study, 39 PAG genes were
identified, all of which were found to be clustered on chromosome 5. Later by using genome
data viewer of NCBI, nucleotide position of known PAG isoforms and their mRNA variants
were identified; where it was observed that all 61 PAG variants were falling only under 9
gene loci. Multiple sequence alignment of PAG protein sequences was done by using
MUSCLE tool, in which exon skipping events were not observed. From the following study it
was found that PAG variants do not have independent gene loci and occurrence of these
variants is not due to splicing. So, one of the possible answers for existence of these large
number of PAG variants might be; rapid karyokinesis in trophoblasts during gestation, that is
not equally followed by cytokinesis, which is why we see BNCs and multinucleated cells in
trophoblast layer of placenta. So, this faster DNA replication is followed by rapid
transcription and translation due to which there might be improper proof- reading activity
resulting in error prone transcription in trophoblast cells of placenta. In the second part of the
research, an ELISA based assay using antibodies against BuPAG 2 isoform to screen
pregnant and non-pregnant sera samples of buffaloes was developed. And from the results it
can be inferred that BuPAG 2 can serve as pregnancy biomarker for detection of pregnancy
in buffaloes significantly at day 35 post AI by ELISA.