Publications by authors named "Tapas Chakraborty"

The coastal district of Bangladesh is susceptible to cyclones, which cause significant damage to infrastructure, economy, and social structures every year. The importance of protecting lives and property in these vulnerable areas is a top priority, especially in times of cyclones and storm surges. Therefore, the identification of potentially suitable shelter locations is essential for disaster risk resilience planning and implementation in the coastal regions.

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  • * Long-term exposure to BAC resulted in significant changes in testis structure, gene expression related to reproduction, and reduced sperm viability, while ovaries showed minimal changes.
  • * BAC exposure led to a significant decrease in the reproductive performance of medaka, including lower fecundity and fertilization rates, underscoring the negative effects of BAC on aquatic ecosystems and the need for further research.
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Steroidogenic acute regulatory protein (Star) plays an essential role in the biosynthesis of corticosteroids and sex steroids by mediating the transport of cholesterol from the outer to the inner membrane of mitochondria. Two duplicated Star genes, namely star1 and star2, have been identified in non-mammalian vertebrates. To investigate the roles of star genes in fish steriodogenesis, we generated two mutation lines of star1 and star1/star2 in Nile tilapia (Oreochromis niloticus).

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Primordial germ cells (PGCs) are pivotal for gonadal development and reproductive success. Though artificial induction of sterility by targeting PGCs are gaining popularity due to its advantages in fish surrogacy and biodiversity management, it is often skill and time intensive. In this study, we have focused on understanding the role of PGCs and the chemotactic SDF-1/CXCR4 signaling on gonad development of Japanese anchovy (JA, Engraulis japonicus), an upcoming marine model organism with eco-commercial values, with an aim to develop a novel, easy, and versatile gonad sterilization method.

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SDF-1/CXCR4 chemokine signaling are indispensable for cell migration, especially the Primordial Germ Cell (PGC) migration towards the gonadal ridge during early development. We earlier found that this signaling is largely conserved in the Japanese anchovy (, EJ), and a mere treatment of CXCR4 antagonist, AMD3100, leads to germ cell depletion and thereafter gonad sterilization. However, the effect of AMD3100 was limited.

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Curcumin, the bioactive compound present in spice plant turmeric, has been shown to exhibit selective phototoxic activities toward mammalian cancer cells, and it is being used extensively as a photosensitizer (PS) in photodynamic therapies (PDT). However, so far, the fate of curcumin toward photochemical transformations is not well understood. Here we report our findings of a number of novel photochemical reaction channels of curcumin in water-methanol mixture, like photoisomerization, photodimerization, and photooxidation (H-loss).

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Germ cells are pivotal for gonadal sexuality maintenance and reproduction. Sex lethal (), the somatic sex determining gene of , is the known regulator and initiator of germ cell femininity in invertebrates. However, the role of the Sxl homologue has rarely been investigated in vertebrates.

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Background: Steroid hormones play an essential role in many reproductive processes of vertebrates. Previous studies revealed that teleost-specific Cyp17a2 (cytochrome P450 family 17 subfamily a 2) might be required for the production of cortisol in the head-kidney and 17α,20β-dihydroxy-4-pregnen-3-one (DHP) in ovary during oocyte maturation. However, the role of Cyp17a2 in male reproduction remains to be largely unknown.

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The structures of tautomers and rotameric forms of curcumin, the bioactive compound present in spice plant turmeric, have been investigated using ion mobility mass spectrometry (IMMS) in conjunction with high-performance liquid chromatography (HPLC) and UV-visible spectroscopy. Two tautomeric forms of this β-diketone compound, keto-enol and diketo, have been chromatographically separated, and the electronic absorption spectra for these two tautomeric forms in methanol solution have been recorded separately for the first time. The molecular identity of the HPLC-separated solution fractions is established unambiguously by recording the mass and fragmentation spectra simultaneously.

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Sex steroids play critical roles in sex differentiation and gonadal development in teleosts. Steroidogenic acute regulatory protein (StAR), transporting cholesterol (the substrate for steroidogenesis) from the outer mitochondrial membrane to the inner membrane, is the first rate-limiting factor of steroidogenesis. Interestingly, two StAR genes (named as StAR1 and StAR2) have been isolated from non-mammalian vertebrates.

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  • Drought significantly impacts agricultural regions, yet traditional monitoring typically focuses on precipitation alone, which can be misleading in places like riverine Bangladesh that have multiple water sources.
  • The study examines vegetation condition, soil moisture, and precipitation trends from 2003 to 2019 in the Northwestern Teesta floodplain using various indices and statistical regression analysis.
  • Findings show improving vegetation and soil moisture conditions, but a decline in meteorological drought since 2007, highlighting the lack of connection between agricultural and meteorological factors, possibly due to increased irrigation and changing cropping patterns.
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  • In 2008, guidelines were established for researching autophagy, which has since gained significant interest and new technologies, necessitating regular updates to monitoring methods across various organisms.
  • The new guidelines emphasize selecting appropriate techniques to evaluate autophagy while noting that no single method suits all situations; thus, a combination of methods is encouraged.
  • The document highlights that key proteins involved in autophagy also impact other cellular processes, suggesting genetic studies should focus on multiple autophagy-related genes to fully understand these pathways.
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  • A variety of sex determination mechanisms exist in vertebrates, ranging from fixed genetic systems in mammals to dynamic sex changes in certain fish species like sequential hermaphroditic fishes.
  • In 1990, a key gene was identified that was essential for sex determination in vertebrates, leading to the discovery of similar genes in species like the medaka fish, indicating a rich diversity of mechanisms across vertebrate species.
  • Recent research has revealed complex interactions between male and female pathway genes during sex differentiation and suggests that even in adult organisms, some vertebrates exhibit a degree of sexual plasticity, providing insight into evolutionary processes and species diversity.
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  • Mid-infrared spectra were measured for hydrogen-bonded complexes of CDCl with different solvents (acetone, cyclohexanone, diethyl ether, and tetrahydrofuran) at room temperature and in a cold argon matrix.
  • Notable changes in spectral shift (Δν) were observed, with acetone and cyclohexanone showing a switch from blue shift in vapor to red shift in the matrix, while the ethers had larger red shifts and enhanced transition intensity.
  • The differences in spectral behavior were explained by charge transfer interactions at H-bonding sites and changes in H-bond distance, with some complexes showing various substructures in
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  • The study investigates the conformational isomers of a hydrogen-bonded complex between -fluorophenol (FP) and cyclopropylamine (CPA) using laser-induced fluorescence spectroscopy in a supersonic jet.
  • Two electronic origin bands were identified in the excitation spectrum, suggesting the presence of distinct isomeric forms, consistent with theoretical predictions.
  • The more stable isomer has additional stabilization from minor hydrogen bonds and shows different spectral features compared to related complexes, with intensity changes related to intermolecular modes analyzed through a Duschinsky rotation approach.
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Autophagy, or cellular self-digestion, is an essential cellular process imperative for energy homeostasis, development, differentiation, and survival. However, the intrinsic factors that bring about the sex-biased differences in liver autophagy are still unknown. In this work, we found that autophagic genes variably expresses in the steroidogenic tissues, mostly abundant in liver, and is influenced by the individual's sexuality.

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An integrated method of ion mobility mass spectrometry and high-performance liquid chromatography (HPLC) has been used to investigate the isomeric distribution of a popular fluorescent dye DCM (4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4-pyran) in methanol solution. Chromatographic separation of DCM isomers in methanol has been performed by probing the molecular mass (DCMH), and two distinctly separated peaks are observed at retention times 3.73 (peak-I) and 3.

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We have demonstrated here, for the first time to our knowledge, the formation of an emitting metastable species upon lowest electronic excitation (S) of a hydrogen-bonded 1:2 complex of -fluorophenol (FP) with ammonia (NH), which is known to be one of the smallest reactive complexes to undergo excited state H-atom transfer (HAT) reaction to produce NH(NH) radical fragment. The emission spectrum of the species is characterized to be red-shifted, broad, and structureless. From the viewpoint of energy balance, an excited state proton transfer (ESPT) is unfavorable, but according to predicted electronic structure parameters, the metastable state species could be stabilized by charge transfer (CT) interaction at the hydrogen-bonded geometry of the complex.

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Mifepristone (RU486), a clinical abortion agent and potential endocrine disruptor, binds to progestin and glucocorticoid receptors and has multiple functional importance in reproductive physiology. A long-term exposure of RU486 resulted in masculinization of female fish, however, the epigenetic landscape remains elusive. Recent studies demonstrated that long non-coding RNAs (lncRNAs) might play potential roles in epigenetic modulation of sex differentiation, ovarian cancer and germline stem cell survival.

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In vertebrates, estrogen receptors are essential for estrogen-associated early gonadal sex development. Our previous studies revealed sexual dimorphic expression of estrogen receptor β2 (ERβ2) during embryogenesis of medaka, and here we investigated the functional importance of ERβ2 in female gonad development and maintenance using a transgenerational ERβ2-knockdown (ERβ2-KD) line and ERβ2-null mutants. We found that ERβ2 reduction favored male-biased gene transcription, suppressed female-responsive gene expression, and affected SDF1a and CXCR4b co-assisted chemotactic primordial germ cell (PGC) migration.

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Mid-infrared spectra of difluoroacetic acid (DFAA) have been measured by isolating the molecule in argon and nitrogen matrices at 8 K and also in the vapor phase at room temperature. In argon matrix, the O-H stretching fundamental (ν) of -COOH group appears as a doublet with band maxima at 3554 and 3558 cm, and a similar doublet for C═O stretching fundamental appears at 1800 and 1810 cm. In the vapor phase, the ν transition is featured with multiple peaks, and the observed band shape has been deconvoluted as superposition of two transitions both having A-type rotational band contours.

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The complement system plays an important role in immune regulation and acts as the first line of defense against any pathogenic attack. To comprehend the red sea bream (Pagrus major) immune response, three complement genes, namely, pmC1r, pmMASP and pmC3, belonging to the classical, lectin and alternative complement cascade, respectively, were identified and characterized. pmC1r, pmMASP, and pmC3 were comprised of 2535, 3352, and 5735 base mRNA which encodes 732, 1029 and 1677 aa putative proteins, respectively.

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Intermolecular proton transfer (IMPT) in a C-H···O hydrogen bonded dimer of an α,β-unsaturated aldehyde, methacrolein (MC), upon nonresonant multiphoton ionization by 532 nm laser pulses (10 ns), has been investigated using time-of-flight (TOF) mass spectrometry under supersonic cooling condition. The mass peaks corresponding to both the protonated molecular ion [(MC)H] and intact dimer cation [(MC)] show up in the mass spectra, and the peak intensity of the former increases proportionately with the latter with betterment of the jet cooling conditions. The observations indicate that [(MC)] is the likely precursor of (MC)H and, on the basis of electronic structure calculations, IMPT in the dimer cation has been shown to be the key reaction for formation of the latter.

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Conformational preferences of a binary hydrogen-bonded complex between p-fluorophenol (pFP) and 2,5-dihydrofuran (DHF) have been studied by means of laser induced fluorescence (LIF) spectroscopy in a supersonic jet expansion. Calculation predicts two major conformers for this complex, one having a nearly linear geometry in which the two molecular moieties are bound only by an O-H···O H-bond, but in the other an additional C-H···π type interaction between an ortho C-H group of pFP and ethylene group of DHF contributes to the binding stabilization and results in a folded geometry for the complex with respect to a global view, although the H-bond angle of the latter is relatively larger. This prediction is realized experimentally by identifying transitions corresponding to the two discrete conformers in a vibrationally resolved LIF excitation spectrum of the complex, and the red shifts of S-S origin band of pFP moiety of the two conformers are 542 and 659 cm, respectively.

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17α, 20β-dihydroxypregn-4-en-3-one (17α, 20β-DP, DHP), a teleost specific biologically active progestin, has been proved to play a critical role in oocytes maturation, ovulation and spermiation. RU486 (Mifepristone, an antagonist of progestin receptor) has been applied in contraceptives, abortion and hormone therapy in clinical medicine. To get further insights into the molecular mechanisms of nuclear progestin receptor (Pgr) activated ovarian differentiation and maintenance, we conducted comparative gonadal transcriptome analysis, and investigated histological and transcriptional differences using 4 months after hatching (mah) RU486-treated XX and control XX/XY Nile tilapia (Oreochromis niloticus).

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