Biology subjects

Abdu, U.

Publications and source records attributed to Abdu, U..

3 recordsLinked to original sources

bioRxiv2023

Mutation in SLC45A2 leads to loss of melanin in parrot feathers

Bird plumage coloration is a complex and multi-factorial process that involves both genetic and environmental factors. Diverse pigment groups contribute to plumage variation in different birds. In parrots, the predominant green color results from the combination of two different primary colors-yellow and blue. Psittacofulvin, a pigment uniquely found in parrots, is responsible for the yellow coloration, while blue is suggested to be the result of light scattering by feather nanostructures and melanin granules. So far, genetic control of melanin-mediated blue coloration has been elusive. In this study, we demonstrated that feather from the yellow mutant rose-ringed parakeet displays loss of melanosome granules in spongy layer of feather barb. Using whole genome sequencing, we found that mutation in SLC45A2, an important solute carrier protein in melanin synthetic pathway, is responsible for the sex-linked yellow phenotype in rose-ringed parakeet. Intriguingly, one of the mutations, P53L found in yellow P. krameri is already reported as P58A/S in the human albinism database, known to be associated with human OCA4. We further showed that mutations in SLC45A2 gene affect melanin production also in other members of Psittaculidae family such as alexandrine, and plum-headed parakeets. Additionally, we demonstrate that the mutations associated with the sex-linked yellow phenotype, localized within the transmembrane domains of the SLC45A2 protein, affect the protein localization pattern. This is the first evidence of plumage color variation involving SLC45A2 in parrots and confirmation of associated mutations in the transmembrane domains of the protein that affect its localization. Article SummaryThe vibrant green tone of parrot plumage emerges from a blend of yellow and blue. While yellow comes from a unique pigment psittacofulvin, the genetics of blue structural color has puzzled scientists. Through novel genetic study, here we identified mutations in SLC45A2 gene, causing loss of melanin in feathers that contributes to the blue structural color. This insight opens a new chapter in understanding avian coloration and the complex interplay of feather microstructure and genetics in natures palette.

developmental biology↗

bioRxiv2021

Revisiting the role of beta-tubulin in Drosophila development: beta-tubulin60D is not an essential gene, and its novel Pin1 allele has a tissue-specific dominant-negative impact

Diversity in cytoskeleton organization and function may be achieved through alternative tubulin isotypes and by a variety of post-translational modifications. The Drosophila genome contains five different {beta}-tubulin paralogs, which may play an isotype tissue-specific function in vivo. One of these genes, the beta-tubulin60D gene, which is expressed in a tissue-specific manner, was found to be essential for fly viability and fertility. To further understand the role of the beta-tubulin60D gene, we generated new beta-tubulin60D null alleles (beta-tubulin60DM) using the CRISPR/Cas9 system and found that the homozygous flies were viable and fertile. Moreover, using a combination of genetic complementation tests, rescue experiments, and cell biology analyses, we identified Pin1, an unknown dominant mutant with bristle developmental defects, as a dominant-negative allele of beta-tubulin60D. We also found a missense mutation in the Pin1 mutant that results in an amino acid replacement from the highly conserved glutamate at position 75 to lysine (E75K). Analyzing the {beta}-tubulin structure suggests that this E75K alteration destabilizes the alpha-helix structure and may also alter the GTP-Mg2+ complex binding capabilities. Our results revisited the credence that beta-tubulin60D is required for fly viability and revealed for the first time in Drosophila, a novel dominant-negative function of missense beta-tubulin60D mutation in bristle morphogenesis. Author summaryDiversity in cell microtubule cytoskeleton organization and function may be achieved through alternative tubulin isotypes and by a variety of post-translational modifications. The expression pattern of different tubulin isotypes (both and {beta} subunits) can vary according to cell type and stage of development, which contribute significantly to cell-specific MT organization and function. In this study, we revisited the role of one of the beta-tubulin isotopes in Drosophila, namely, beta-tubulin60D. This is the first study where a well molecularly defined protein null allele of {beta}Tub60D was generated and characterized. This well-characterized {beta}Tub60D allele demonstrated unambiguity that {beta}Tub60D is not an essential gene, as was described before. Moreover, we identified Pin1, an unknown dominant mutant with bristle developmental defects, as a dominant-negative allele of beta-tubulin60D. We also found a missense mutation in the Pin1 mutant that results in an amino acid (E75K). Analyzing the {beta}-tubulin structure suggests that this E75K alteration destabilizes the alpha-helix structure and may also alter GTP-Mg2+ complex binding capabilities. Thus, our results also revealed for the first time in Drosophila, a novel dominant-negative function of a missense beta-tubulin60D mutation, which has a tissue-specific function.

developmental biology↗

bioRxiv2018

GFP-Forked, a genetic reporter for studying Drosophila oocyte polarity

The polarized organization of the Drosophila oocyte can be visualized by examining the asymmetric localization of mRNAs, which is supported by networks of polarized microtubules (MTs). In this study, we used the gene forked, the putative Drosophila homologue of espin, to develop a unique genetic reporter for asymmetric oocyte organization. We generated a null allele of the forked gene using the CRISPRCas9 system and found that forked is not required for determining the axes of the Drosophila embryo. However, ectopic expression of a truncated form of GFP-Forked generated a distinct network of asymmetric Forked, which first accumulated at the oocyte posterior and was then restricted to the anterolateral region of the oocyte cortex in mid-oogenesis. This localization pattern resembled that reported for the polarized MTs network. Indeed, pharmacological and genetic manipulation of the polarized organization of the oocyte showed that the filamentous Forked network diffused throughout the entire cortical surface of the oocyte, as would be expected upon perturbation of oocyte polarization. Finally, we demonstrated that Forked associated with Short-stop and Patronin foci, which assemble non-centrosomal microtubule-organizing centers. Our results thus show that clear visualization of asymmetric GFP-Forked network localization can be used as a novel tool for studying oocyte polarity.\n\nSummary statementThe novel asymmetric Forked network could be used as a genetic reporter for visualizing and studying oocyte polarity.

developmental biology↗