• SANTOSH KUMAR

      Articles written in Journal of Genetics

    • Dual modified antiphospho (Ser10)-acetyl (Lys14)-histone H3 predominantly mark the pericentromeric chromatin during mitosis in monokinetic plants

      SANTOSH KUMAR SHARMA MAKI YAMAMOTO YASUHIKO MUKAI

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      Epigenetic regulatory posttranslational histone modification marks not only function individually but also capable to act in combination as a unique pattern. A total of 16 plant species belonging to 11 genera of eight families (five dicots and threemonocots) including land plants, epiphytes (orchids) and the holokinetic taxa (Drosera spp.) were analysed for chromosomal distribution of dual modified antiphospho (Ser10)-acetyl (K14)-histone H3 (H3S10phK14ac) to understand the combinatorial chromatin dynamics during mitotic cell division in plants. The anti-H3S10phK14ac evidently mark the pericentromeric chromatin on mitotic chromosomes of the plants excluding the holokinetic Drosera species, which revealed the immunolabelling of whole chromosomes all along the arms. The dual modified immunosignals were absent during early stages of mitosis, appeared intensively at metaphase and remained visible until late-anaphase/telophase however, labelled the whole chromosomes during meiotic metaphase I. Colocalization of anti-H3S10phK14ac with an onion’s CENH3 antibody on mitoticchromosomes of Allium revealed the chromosomal location of anti-H3S10phK14ac in the region between signals for CENH3 detection. Overall analysis suggests that the unique localization of combinatorial histone modification mark at pericentromericchromatin might have attributed through ‘phospho-acetyl’ cross talk that ultimately facilitate the sister chromatid cohesion at pericentromeres following condensation events in mitotic chromosomes. Here, we propose that dual modified H3S10phK14ac histone may serve as an additional cytogenetic landmark to identify pericentromeric chromatin during mitosis in plants. The plausible role of histone cross talk and future perspectives of combinatorial histone modification marks in plant cytogenetics with special reference to chromatin dynamics have been discussed.

    • Novel mutation in Cul7 gene in a family diagnosed with 3M syndrome

      SHAGUFTA SHAIKH SURESH K. G. SHETTIGAR SANTOSH KUMAR SURITA KANTHARIA JAGANNATH KURVA SUSAN CHERIAN

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      This study evaluates a family with two siblings having severe growth retardation and facial dysmorphism, born to consanguineous normal healthy parents. Affymetrix CytoScan 750K microarray showed a 34-Mb pericentric homozygous region on chromosome 6 for both siblings. CUL7 was one of the 141 genes present in this region. Sanger sequencing of CUL7 gene detected a 2-bp novel deletion in the 15th exon (c.2943_2944delCT of the cDNA). This deletion leads to a frameshift and a premature termination signal much upstream of the wild-type termination signal, leading to a nonsense mediated decay of the mRNA. CUL7 protein plays an important role in formation of 3M complex, ubiquitination, microtubule dynamics and cell cycle regulation. Mutations in CUL7 gene is known to cause a rare 3M syndrome. Information about the novel mutation has been accepted in the ClinVar database with rs1064792895.

    • Prevalence of Y chromosome microdeletion in north Indian infertile males with spermatogenesis defect

      HIMANSHU SHARMA UJJAWAL SHARMA SANTOSH KUMAR SHRAWAN KUMAR SINGH RAVI MOHAN S. MAVADURU RAJENDRA PRASAD

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      Deletion of specific genes present in the long arm of Y chromosome has been identified as the most common genetic cause of defective spermatogenesis. Studies have shown that frequency of Y chromosome microdeletion varies in different geographical location and is related to genetic and environmental influence preponderance. Therefore, the present study was carried out to identify the frequency of Y chromosome microdeletion in the northern region of India and to define subgroup of infertile patients who are critically under more risk of having microdeletion. A total of 292 north Indian infertile males with nonobstructive azoospermia and oligozoospermia were selected for screening the Y chromosome microdeletion. Healthy fertile males (n=100) were also enrolled as control subjects. Frequency of Y chromosome microdeletion in north Indian infertile males was found to be about 8.5%, with azoospermia factor (AZFc) region as the most susceptible region for microdeletion. Comparatively microdeletion is more common in patients with nonobstructive azoospermia thanoligozoospermia (9.2% versus 7.1%). Statistical analysis also revealed that patients with hormonal FSH level between 20 and 40 mIU/mL have more chances of harbouring microdeletion. Hence, the present study highlights the importance of screening AZFc region among infertile patients with very high serum FSH value.

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