Biology subjects

Halder, S.

Publications and source records attributed to Halder, S..

23 records · Page 2Linked to original sources

bioRxiv2021

Phytoremediation of EMS Induced Brassica juncea Heavy Metal Hyperaccumulator Genotypes

Buriganga, an economically important river of Dhaka, Bangladesh, is highly polluted by different toxic heavy metals. In this study, phytoremediation of EMS induced Indian mustard (Brassica juncea L) genotypes against three pollutants viz. lead (Pb), chromium (Cr) and cadmium (Cd) of Buriganga riverbank soil was assessed in field condition. Among 1-, 2- and 3% EMS induced genotypes, better seed germination rate, germination speed and plant survival rate were observed in 1% EMS induced genotype, BE21. The highest concentration of Pb, Cr and Cd were also obtained in the leaf of BE21 genotype and therefore was considered as a super-hyperaccumulator genotype. Concentration of Pb in the next generation of this genotype was approximately two-fold higher in the root (91.53{+/-}6.59 mg/kg dry weight, DW); three-fold higher in the shoot (33.31{+/-}1.01 mg/kg DW) and leaf (28.35{+/-}3.61 mg/kg DW), and more in the fruit (5.59{+/-}0.93 mg/kg DW) than the control. Concentration of Cr was approximately two-fold in the root (57.02{+/-}3.24 mg/kg DW), shoot (18.51{+/-}1.36 mg/kg DW) and leaf (14.98{+/-}2.01 mg/kg DW), and more in the fruit (6.15{+/-}1.92 mg/kg DW) of BE21 genotype compared to the control. Cd concentration was more in the root (1.96{+/-}0.92 mg/kg DW), leaf (0.52{+/-}0.32 mg/kg DW) and fruit (0.19{+/-}0.02 mg/kg DW) and less in the shoot (0.19{+/-}0.01 mg/kg DW) of BE21 genotype than the control. Root, shoot, leaf and fruit of BE21 altogether accumulated 98-, 73- and 87% Pb, Cr and Cd, respectively and can thus be utilized to remove heavy metals of Buriganga River. As like root, shoot and leaf, fruit also accumulated heavy metals; hence those plants which are used in phytoremediation should not be used as food or fodder. To the best of our knowledge, this is the first report of developing EMS induced hyperaccumulator genotype of B. juncea for phytoremediation of Buriganga riverbank soil of Bangladesh.

plant biology↗

bioRxiv2021

Evolution of increased early-life fecundity but faster reproductive senescence in Drosophila melanogaster females through adaptation to chronic live-yeast deprivation

Reproductive output is often constrained by availability of macronutrients, especially protein. Long term protein restriction, therefore, is expected to select for traits that maximize reproductive output in spite of such nutritional challenge. We subjected four replicate populations of Drosophila melanogaster to a complete deprivation of live-yeast supplement, thereby mimicking a protein restricted ecology. As yeast supplement is a key source of protein, such an ecology is expected to strongly limit reproductive output, especially in females. Following 24 generations of experimental evolution, compared to their matched controls, females from experimentally evolved populations showed increase in reproductive output early in life, both in presence and absence of yeast supplement. The observed increase in reproductive output was not associated with any accommodating alteration in egg size; and development time, pre-adult survivorship, and body mass at eclosion of the progeny. There was no evidence for evolution of lifespan and lifelong cumulative reproductive output in females. However, females from experiment regime were found to have a significantly faster rate of reproductive senescence, as indicated by a faster rate of age related decline in reproductive output following the attainment of the reproductive peak. Therefore, adaptation to yeast deprivation ecology in our study involved a novel reproductive strategy whereby females attained higher reproductive output early in life followed by faster reproductive aging. To the best of our knowledge, this set of results is one of the most clear demonstration of optimization of fitness by fine tuning of reproductive schedule during adaptation to a prolonged nutritional deprivation. Supplementary informationA separate file that includes three figures and six tables.

evolutionary biology↗

bioRxiv2020

Dual-purpose isocyanides produced by Aspergillus fumigatus contribute to cellular copper sufficiency and exhibit antimicrobial activity

The maintenance of sufficient but non-toxic pools of metal micronutrients is accomplished through diverse homeostasis mechanisms in fungi. Siderophores play a well-established role for iron homeostasis; however, no copper-binding analogs have been found in fungi. Here we demonstrate that in Aspergillus fumigatus isocyanides derived from the xan biosynthetic gene cluster (BGC) bind copper, impact cellular copper content, and have significant metal-dependent antimicrobial properties. xan BGC-derived isocyanides are secreted and bind copper as visualized by a chrome azurol S (CAS) assay and inductively coupled plasma-mass spectrometry (ICP-MS) analysis of A. fumigatus intracellular copper pools demonstrated a role for xan cluster metabolites in the accumulation of copper. A. fumigatus coculture with A. nidulans, Candida albicans and a variety of pathogenic bacteria establish copper-dependent antimicrobial properties of xan BGC metabolites including inhibition of laccase activity. Similarly, inhibition of Pseudomonas aeruginosa by low concentrations of the xan isocyanide xanthocillin was copper-dependent. Other metals also reduced xanthocillins antimicrobial properties, but less efficiently than copper. As variations of the xan BGC exist in other filamentous fungi, we suggest that xanthocillin-like natural products represent a first example for fungal small molecules that serve to maintain copper sufficiency and mediate interactions with competing microbes. SignificanceMetal homeostasis is an integral part of metabolism for any organism. A vast array of small molecules are already known to mediate metal homeostasis in fungi and bacteria; however, unlike their bacterial counterparts, to-date there are no known fungal small molecules that function to maintain copper homeostasis. Discovery of copper binding small molecules produced by A. fumigatus gives insight into mechanisms other than the extensively studied copper transporters or metalloproteins for how fungi can regulate copper. This has important ecological implications as securing scarce nutrients is central for fitness and survival. Additionally, studying this mechanism in A. fumigatus provides a basis for investigation of copper regulation pathways in other fungi.

microbiology↗

bioRxiv2019

Assessing the specificity of the relationship between brain alpha oscillations and tonic pain

Recent research has pointed to alpha brain oscillations as a potential clinical biomarker for sensitivity to pain. In particular, researchers claimed that the slowing of individual alpha frequency (IAF) could be an objective marker of pain during prolonged nociceptive stimulation. However, prolonged pain has been also associated with increased IAF. To date, there is insufficient evidence to conclude that IAF can be a neural marker of pain.\n\nThe current study aimed at elucidating the conflicting findings by assessing the specificity of the relationship between brain alpha oscillations and tonic pain. We recorded electroencephalography (EEG) on healthy volunteers during exposure to consecutive 5-minute sessions of painful hot water immersion, innocuous warm water immersion and an aversive, non-painful auditory stimulus, matched by unpleasantness to the painful condition. Participants rated stimulus unpleasantness throughout each condition. We also asked participants to sit still with eyes closed and eyes open right before and after the three experimental conditions in order to obtain a robust estimate of baseline alpha. Our findings revealed both increased and decreased IAF during tonic hot stimulation depending on the alpha range targeted (7-13 Hz vs. 8-10 Hz). In addition, they provide mild evidence for a negative relationship between IAF and the unpleasantness of the experience. Finally, we could not identify a difference between IAF during tonic hot temperature and during tonic auditory experience. Altogether, these findings emphasize a twofold frequency pattern (increase vs. decrease) for IAF during tonic thermal pain, thus indicating the need for robust methodological scrutiny of IAF as a neural marker of pain.

neuroscience↗

bioRxiv2018

SPRTN Protease and Checkpoint Kinase 1 Cross-Activation Loop Safeguards DNA Replication

The SPRTN metalloprotease is essential for DNA-protein crosslink (DPC) repair and DNA replication in vertebrate cells. Cells deficient in SPRTN protease activity exhibit severe DPC-induced replication stress and genome instability, manifesting as premature ageing and liver cancer in humans and mice. Strikingly, SPRTN-deficient cells also show a severe G2/M checkpoint defect and fail to activate a robust checkpoint kinase 1 (CHK1) signalling cascade normally triggered in response to replication stress. Here, we show that SPRTN activates the CHK1 signalling cascade during physiological (steady-state) DNA replication by proteolysis-dependent eviction of CHK1 from chromatin. The N-terminal CHK1 fragments cleaved by SPRTN protease still possess kinase activity and phosphorylate SPRTN. This CHK1-dependent phosphorylation stimulates SPRTN recruitment to chromatin to further promote CHK1 eviction from chromatin, DPC removal and unperturbed DNA replication. Our data suggest that a SPRTN-CHK1 cross-activation loop is essential for steady-state DNA replication and protection from DNA replication stress, a major source of genome instability in diseases that cause premature ageing and cancer. In addition, we disclose a mechanism of CHK1 activation during physiological DNA replication, when long stretches of single stranded (ss) DNA that are induced by genotoxic stress and activate canonical and robust CHK1 signalling are not present.

cell biology↗