Browsing by Author "Abdin, Malik Zainul"

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In vivo role of Candida albicans β-hexosaminidase (HEX1) in carbon scavenging
(John Wiley & Sons, 2015) Ruhela, Deepa; Kamthan, Mohan; Saha, Paramita; Majumdar, Subeer S.; Datta, Kasturi; Abdin, Malik Zainul; Datta, Asis
The capability to utilize of N-acetylglucosamine (GlcNAc) as a carbon source is an important virulence attribute of Candida albicans. But there is a lack of information about the in vivo source of GlcNAc for the pathogen within the host environment. Here, we have characterized the GlcNAc-inducible β-hexosaminidase gene (HEX1) of C. albicans showing a role in carbon scavenging. In contrast to earlier studies, we have reported HEX1 to be a nonessential gene as shown by homozygous trisomy test. Virulence study in the systemic mouse murine model showed that Δhex1 strain is significantly less virulent in comparison to the wild-type strain. Moreover, Δhex1 strain also showed a higher susceptibility to peritoneal macrophages. In an attempt to determine possible substrates of Hex1, hyaluronic acid (HA) was treated with purified Hex1 enzyme. A significant release of GlcNAc was observed by gas chromatography-mass spectrometry analysis analysis suggesting HA degradation. Interestingly, immunohistochemistry analysis showed significant accumulation of HA in the mice kidney infected with the wild-type strain of C. albicans. Northern blot analysis showed that C. albicans HEX1 is expressed during mice renal colonization. Thus, C. albicans can obtain GlcNAc during organ colonization by secreting Hex1 via degradation of host HA.
Potential regulation of cleistogamy in pigeonpea through jasmonic acid and bHLH transcription factor interactions
(Springer Nature Publishing AG, 2025) Gupta, Palak; Srivastava, Harsha; Kumar, Kuldeep; Nirgude, Machindra; Arpita, Kumari; Vadassery, Jyothilakshmi; Sharma, Sandhya; Abdin, Malik Zainul; Gaikwad, Kishor
This study provides insights into the molecular and hormonal control of cleistogamy in pigeonpea, focusing on bHLH transcription factors and jasmonic acid pathway. Pigeonpea, an annual diploid (2n = 22) grain legume, holds significant nutritional value in cereal-dominated diets. The chasmogamous flowers of pigeonpea have a typical 9 + 1 diadelphous stamen where flowers open pre-fertilization resulting in cross-pollination. In contrast, a cleistogamous genotype characterized by polyadelphous stamens and flowers that open post-fertilization ensuring seed purity was analyzed for identifying causal pathways. Subsequent analysis focused on a set of transcription factors and their interaction with the hormonal networks associated with cleistogamy. Genes of the Jasmonic acid (JA) signaling pathway have been established to play a significant role in inducing cleistogamy and one of the key regulators of the JA pathway is bHLH (basic helix loop helix). A genome-wide survey identified 176 bHLH genes in the pigeonpea genome. Phylogenetic analysis classified 176 bHLH genes into 21 subfamilies distributed randomly across the genome. Gene ontology, cis-motifs analysis in the upstream region, and protein-protein interaction network implied the involvement of these genes in various biological processes. Expression analysis of key genes of the jasmonic acid pathway which includes MYC2 (Cc_bHLH135) along with its interacting partners TIFY/JAZ in chasmogamous and cleistogamous floral tissues revealed their potential role in flower opening. The results of UHPLC-MS/MS quantitation of Jasmonic acid and its bioactive form JA-Ile align with the expression analysis. The congruence of gene expression and hormone profiling highlights the involvement of the JA pathway in regulating flower opening, implying their potential role in cleistogamy in pigeonpea.