Browsing by Author "Kumar, P"

Now showing 1 - 17 of 17
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    Abiotic stress tolerance and antifungal activities of rhizobacteria for the management of soil-borne pathogens
    (14-05) Poria, V; Jhilta, P; Kumar, S; Kumar, P
    Cotton production is negatively affected by both biotic (diseases and insects) and abiotic (high temperature, salinity, water deficit, and extreme pH) factors. Soil-borne diseases, especially wilts and rots, significantly reduce cotton yield. Thus, we aimed to isolate and identify multi-stress tolerant bacterial antagonistic agents (AGAs) against two major soil-borne pathogens, Macrophomina phaseolina and Fusarium oxysporum. A total of 132 isolates with distinct morphologies were recovered from 25 different rhizospheric soil samples of cotton. A dual culture plate and broth assay confirmed the antagonistic activity of the isolates against these phytopathogens. Four selected AGAs thrived in salt stress induced by different NaCl concentrations, up to 1.71 M, except for isolate 62, which survived up to 0.85 M. Under osmotic stress, all the AGAs were tolerant of up to − 1.03 MPa. Similarly, all the AGAs were able to survive over a temperature range of 20–50 ◦C except for isolate 62, which survived up to 45 ◦C and was regarded as thermotolerant. All four AGAs were able to grow at pH values ranging from 5 to 9. AGA 18 and S46-7 survived under highly acidic conditions (pH 4). These multi-stress tolerant AGAs also exhibited different plant growth-promoting activities, such as mineral solubilization, ACC-deaminase production, and IAA production. Molecular identification revealed the following AGAs: Bacillus siamensis SSVP1 (18), Bacillus halotolerans SSVP2 (34), Pseudomonas aeruginosa SSVP3 (62), and Bacillus tequilensis SSVP4 (S46-7). AGAs with multiple stress tolerance traits can serve as potential biocontrol agents in the field to reduce pesticide consumption in cotton-growing areas.
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    Behavioral study of self-compacting concrete with wollastonite microfiber as part replacement of sand for pavement quality concrete (PQC)
    (2019-07) Jindal, A; Ransinchung R.N., G.D; Kumar, P
    The fact that self-compacting concrete (SCC) does not require any supplementary com paction to fill in every nook and corner of the structure without compromising with strength and durability makes it much more futuristic and desirable over conventional concrete. Present study highlights the behavioural changes in SCC for PQC applications at macro and micro levels with the incorporations of wollastonite micro-fiber; proposed to be used for restoration of deteriorated pavement quality concrete slab. Wollastonite micro-fiber was incorporated as part replacement of fine aggregates in proportions of 10–50% with an offset of 10%. Different properties of SCC mixes such as flow-ability, seg regation resistance and filling ability were investigated in fresh state while mechanical properties including compressive strength, flexural strength and hardened density were studied in hardened states. The SCC mixes were also investigated for estimating effect of incorporating wollastonite micro-fiber in hydrated states of cement mortar. Inclusions of wollastonite micro-fiber in SCC enhanced the cohesiveness of the mix thereby improving the density and reducing its water absorption. SCC mixes with wollastonite micro-fiber showed higher flexural and comparable compressive strength parameters than those of conventional SCC mix. SCC mix with 30% wollastonite micro-fiber as a replacement of fine aggregates provides similar strength and better repair prospects as compared to conven tional SCC or normal concrete mix.
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    Comprehensive scientific examination of leg length discrepancy in junior badminton players
    (2023-10) Kumar, P; Singh, R
    The objective of this research was to conduct a comprehensive analysis of Leg Length Discrepancy (LLD) among in young badminton players with the aim of mitigating back discomfort and reducing injuries in their current training environments. Numerous studies have established a connection between LLD and various musculoskeletal issues in different sports, causing asymmetrical gait and low back pain. Consequently, many players find their daily routines disrupted, leading to burnout or dropout from the sport. To assess the current situation, this study focused on 1502 young badminton players aged 9–12 from the states of Tamil Nadu and Puducherry. LLD can be challenging to diagnose and treat, especially in growing children, and various methods and equipment are available for assessment. In this research, the "Delta Leg" (DL) measuring tool was employed, measuring discrepancies from millimeters to centimeters. The 0–10 Numeric Pain Rating Scale was used to determine the level of pain. The analysis involved the application of percentage techniques (P = n × 100 / N) and Pearson correlation. The results indicated that 218 (15%) of the players had equal-length lower limbs, while 1284 (85%) exhibited LLD in varying degrees. Among the LLD players, 354 (24%) had discrepancies greater than 1 cm, 753 (50%) had discrepancies less than 1–2 cm, 171 (11%) had discrepancies less than 2–3 cm, and 6 (0.40%) had discrepancies less than 3 cm. LLD was notably prevalent among young badminton players aged 9 to 12, warranting careful attention. Even mild LLD should not be overlooked, emphasizing the importance of coaches, physiotherapists, physical education instructors, and doctors in closely monitoring players' leg mechanics. Immediate corrective actions are essential, and continuous monitoring is imperative, because LLD may necessitate intervention before reaching skeletal maturity. The use of insoles is recommended to alleviate muscular and/or joint problems and gait issues in players. Additionally, some players with equal leg lengths exhibited pronation and supination in their ankles, suggesting the need for future research to explore other lower limb issues experienced by badminton players.
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    Comprehensive scientific examination of leg length discrepancy in junior badminton players
    (2023-10) Kumar, P; RAM MOHAN SINGH, R; Ajithkumar, L
    The objective of this research was to conduct a comprehensive analysis of Leg Length Discrepancy (LLD) among in young badminton players with the aim of mitigating back discomfort and reducing injuries in their current training environments. Numerous studies have established a connection between LLD and various musculoskeletal issues in different sports, causing asymmetrical gait and low back pain. Consequently, many players find their daily routines disrupted, leading to burnout or dropout from the sport. To assess the current situation, this study focused on 1502 young badminton players aged 9–12 from the states of Tamil Nadu and Puducherry. LLD can be challenging to diagnose and treat, especially in growing children, and various methods and equipment are available for assessment. In this research, the "Delta Leg" (DL) measuring tool was employed, measuring discrepancies from millimeters to centimeters. The 0–10 Numeric Pain Rating Scale was used to determine the level of pain. The analysis involved the application of percentage techniques (P = n × 100 / N) and Pearson correlation. The results indicated that 218 (15%) of the players had equal-length lower limbs, while 1284 (85%) exhibited LLD in varying degrees. Among the LLD players, 354 (24%) had discrepancies greater than 1 cm, 753 (50%) had discrepancies less than 1–2 cm, 171 (11%) had discrepancies less than 2–3 cm, and 6 (0.40%) had discrepancies less than 3 cm. LLD was notably prevalent among young badminton players aged 9 to 12, warranting careful attention. Even mild LLD should not be overlooked, emphasizing the importance of coaches, physiotherapists, physical education instructors, and doctors in closely monitoring players' leg mechanics. Immediate corrective actions are essential, and continuous monitoring is imperative, because LLD may necessitate intervention before reaching skeletal maturity. The use of insoles is recommended to alleviate muscular and/or joint problems and gait issues in players. Additionally, some players with equal leg lengths exhibited pronation and supination in their ankles, suggesting the need for future research to explore other lower limb issues experienced by badminton players.
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    Cool green-emissive Y2Si2O7:Tb3+ nanophosphor: auto-combustion synthesis and structural and photoluminescence characteristics with good thermal stability for lighting applications†
    (2024-05) Kumar, P; Singh, D; Kadyan, S; Kumar, H; Kumar, R
    A cheap, versatile, sustainable and energy-efficient gel-combustion method was applied to develop a series of green-emitting down-converted Y2Si2O7:Tb3+ (YPS:Tb3+) nanophosphors. Employing XRD-based Rietveld refinement approach, the phase purity and crystallographic evaluation of the produced phosphor were conducted, revealing a triclinic crystal with P 1 space group. EDX and TEM analyses were performed on the synthesized samples to determine their elemental composition and morphological properties. Diffuse reflectance spectra yielded 5.61 eV and 5.79 eV optical energy band gaps for the host and the optimized (0.04 mole of Tb3+) sample, respectively. UV light has the ability to excite the nanocrystalline phosphor in an efficient manner, leading to significant luminosity qualities attributed to the radiative relaxation of 5 D4 / 7 FJ (J = 6, 5, 4, 3). The bi-exponential decay function was derived by the PL decay curves. With an activation energy of 0.2206 eV, the Y1.96Si2O7:0.04Tb3+ phosphor exhibits good thermal quenching capabilities. Improved photometric attributes including CIE coordinates, CCT and color purity confirmed the green glow, indicating a strong competitor for cool-green emission in lighting applications
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    Determining the optimal duration of plyometric training for enhancing vertical jump performance: a systematic review and meta analysis
    (2023) Kumar, D; Dhull, S; Nara, K; Kumar, P
    Introduction. Plyometric training is done in many ways, but countermovement jumps and squat jumps are easy and safe methods involving minimal use of equipment to increase lower body muscular power. There is enough evidence in the literature to support the notion that plyometric training increases vertical jump height. But the combination of countermovement jumps and squat jumps and its impact on vertical jump height is still unclear. Purpose. Therefore, to examine the importance of various plyometric training techniques, this meta-analytical evaluation was created. Materials and Methods. PubMed, MEDLINE, and Google Scholar databases were searched through August 2022. Empirical studies are expressed in the English language and issued within the last twenty-eight years. Included squat jump and countermovement jump interventions for improving vertical jump height. The studies used a training duration of a minimum of four weeks or above involving a control group included. As an approach to plyometric training that raises vertical jump height, the effects of countermovement jump and squat jump training were evaluated. To assess the level of heterogeneity, the I2 statistics were utilized. The value of I2 above 75% indicates significant heterogeneity and leads to the subgroup analysis method. Summary effects were calculated using standardized mean difference. With the help of the Cochrane tool, the risk of bias was assessed. Results. The 22 study results all met the enclosure criteria. The meta-analysis indicated that the total impact of squat jumps training had high effects on vertical jump height [Effect Size = 0.96, (95% CI,0.57 to 1.35)]. A moderate degree [Effect Size = 0.91, (95 % CI,0.46 to 1.37)] of effects of countermovement jumps training on vertical jump height was reported by included interventions. Lesser than 10 weeks of plyometric training intervention duration they probably had a small effect on countermovement jumps [Effect Size = 0.79, (95 % CI, 0.30 to 1.29)]. Conclusion: Squat jumps and countermovement jumps are an efficient kind of training to increase the vertical jump height of male and female athletes, according to our study on plyometric training. Higher posttests mean differences were found in the studies including male subjects. The length of intervention has proportional effects on vertical jump height the recommended length of training should lie between 8 to 12 weeks. The effect size ranged between small to large degrees was observed in overall and subgroup analysis.
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    Developments in conducting polymer-, metal oxide-, and carbon nanotube-based composite electrode materials for supercapacitors: a review
    (2024-03) Tundwal, A; Kumar, H; Binoj, B; Sharma, R; Kumar, G; Kumari, R; Dhayal, A; Yadav, A; Singh, D; Kumar, P
    Supercapacitors are the latest development in the field of energy storage devices (ESDs). A lot of research has been done in the last few decades to increase the performance of supercapacitors. The electrodes of supercapacitors are modified by composite materials based on conducting polymers, metal oxide nanoparticles, metal–organic frameworks, covalent organic frameworks, MXenes, chalcogenides, carbon nanotubes (CNTs), etc. In comparison to rechargeable batteries, supercapacitors have advantages such as quick charging and high power density. This review is focused on the progress in the development of electrode materials for supercapacitors using composite materials based on conducting polymers, graphene, metal oxide nanoparticles/nanofibres, and CNTs. Moreover, we investigated different types of ESDs as well as their electrochemical energy storage mechanisms and kinetic aspects. We have also discussed the classification of different types of SCs; advantages and drawbacks of SCs and other ESDs; and the use of nanofibres, carbon, CNTs, graphene, metal oxide– nanofibres, and conducting polymers as electrode materials for SCs. Furthermore, modifications in the development of different types of SCs such as pseudo-capacitors, hybrid capacitors, and electrical double-layer capacitors are discussed in detail; both electrolyte-based and electrolyte-free supercapacitors are taken into consideration. This review will help in designing and fabricating high-performance supercapacitors with high energy density and power output, which will act as an alternative to Li-ion batteries in the future.
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    Efficient two‑step lactic acid production from cassava biomass using thermostable enzyme cocktail and lactic acid bacteria: insights from hydrolysis optimization and proteomics analysis
    (2020-08) Sharma, A; Kumar, P; Singh, S
    Lactic acid is an intermediate-volume specialty chemical, used in the production of biodegradable polymers and other chemi cals. Although lactic acid production process is well established, however, the cost of production is very high. Therefore, in this study; starchy biomass (cassava) was hydrolyzed with in-house enzyme cocktail prepared from Aspergillus foetidus MTCC508 and Bacillus subtilis RA10. Process optimization using Taguchi experimental design helped to optimize the most efective ratio of fungal and bacterial amylase for efective saccharifcation of cassava. A higher sugar yield of 379.63 mg/ gds was obtained under optimized conditions, using 30 U/gds of bacterial enzyme and 90 U/gds of the fungal enzyme at pH 4 within 48 h of saccharifcation. Among 11 lactic acid bacteria isolated, Lactobacillus fermentum S1A and Lactobacillus farraginis SS3A produced the highest amount of lactic acid 0.81 g/g and 0.77 g/g, respectively, from the cassava hydro lysate. The study proved the potential renewable source of cassava biomass as a source for fermentable sugars that can be fermented to lactic acid with high yield. In future, this cost-efective and environmental-friendly bioprocess can be upscaled for industrial lactic acid production
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    GMPP Tracking of Solar PV system using Spotted Hyena and Quadratic Approximation based Hybrid Algorithm under Partially shaded conditions
    (2023) Kumar, P; Kumar, M; Bansal, A
    The demand for clean and renewable energy is increasing due to environmental concerns. Photovoltaic (PV) system is very popular from the renewable sources and its usage is increasing. The PV system power transfer efficiency depends on several factors such electrical characteristics of loads, solar irradiation, shading condition and panel temperature. The process of transferring maximum possible power to load from PV system by adjusting the system parameters is called maximum power point tracking (MPPT). Under the partially shaded conditions, multiple power peaks are created in the PV curves and makes the MPPT is a non-convex problem. It is a challenging problem to track the global maximum power point (GMPP) under partially shaded conditions. It is essential to recognize the GMPP and restart the string as early as possible to prevent the physical as well as economical damage. In this paper, a new hybrid algorithm for MPPT is proposed and called as QASHO, a combination of Spotted Hyena optimization (SHO) and Quadrature approximation (QA) technique. The QASHO is used to track the GMPP under different weather conditions such as partial shading. The simulation results are compared with Perturb and Observe (P&O) algorithm and Cuckoo Search optimization (CSO) algorithm and promised for better performance in tracking GMPP. The experimental results are provided to validate the proposed MPPT methodology.
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    A green light emissive LaSr2AlO5:Er3+ nanocrystalline material for solid state lighting: crystal phase refinement and down-conversion photoluminescence with high thermal stability
    (2024-09) Kumar, P; Singh, D; Kumar, H
    The present study reveals the structural and optoelectronic characteristics of a down-converted (DC) green luminous Er3+ doped LaSr2AlO5 phosphor that was produced by employing an efficient and reliable gel combustion process assisted with urea as a fuel. Using Rietveld refinement of diffraction data, the crystal structure and phase formation were examined. The surface morphology and elemental configuration of the phosphor were analyzed via TEM and EDX spectroscopy, respectively. The band gap of LaSr2AlO5 (5.97 eV) and optimized La0.96Sr2AlO5:4 mol% Er3+ (5.51 eV) classify the optimized sample as a direct band-gap material. The PL peaks located in the visible range corresponding to transitions 2 H9/2 / 4 I15/2 (406 nm), 2 H11/2 / 4 I15/2 (520 nm), 4 S3/2 / 4 I15/2 (550 nm), and 4 F9/ 2 / 4 I15/2 (665 nm) were revealed by photoluminescence spectroscopy under 377 nm excitation. Above 4 mol% Er3+ doping, concentration quenching was observed, which was controlled by the quadrupole–quadrupole interaction. Based on the findings of the double exponential fitting of lifetime curves acquired from the emission spectra at lex = 377 nm and lem = 550 nm, the average lifetime of the excited levels of considered nanomaterials was estimated. The temperature-dependent emission spectra of the La0.96Sr2AlO5:4 mol% Er3+ sample were collected in the range 298–498 K. The considered phosphor was found to have a high thermal stability as evidenced by the luminous intensity being sustained at 74.29% at 498 K compared to the intensity at ambient temperature (298 K) with an activation energy of 0.1453 eV. The calculated color purity and superb chromaticity coordinates indicates that the phosphors have a high degree of color purity, which further supports its applicability as a green component in solid-state lighting.
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    Insights into the mechanism of mycelium transformation of Streptomyces toxytricini into pellet
    (2023-08) Kumar, P; Khushboo; Rajput, D; Dubey, K
    Formation of the mycelial pellet in submerged cultivation of Streptomycetes is unwanted in industrial fermentation processes as it imposes mass transfer limitations, changes in the rheology of a medium, and affects the production of secondary metabolites. Though detailed information is not available about the factors involved in regulating mycelial morphology, it is studied that culture conditions and the genetic information of strain play a crucial role. Moreover,the proteomic study has revealed the involvement of low molecular weight proteins such as; DivIVA, FilP, ParA, Scy, and SsgA proteins in apical growth and branching of hyphae, which results in the establishment of the mycelial network. The present study proposes the mechanism of pellet formation of Streptomyces toxytricini (NRRL B-5426) with the help of microscopic and proteomic analysis. The microscopic analysis revealed that growing hyphae contain a bud like structure behind the apical tip, which follows a certain organized path of growth and branching, which was further converted into the pellet when shake flask to the shake flask inoculation was performed. Proteomic analysis revealed the production of low molecular weight proteins ranging between 20 and 95 kDa, which are involved in apical growth and hyphae branching and can possibly participate in the regulation of pellet morphology.
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    Photovoltaic (PV) Parameter Extraction using a Hybrid Algorithm based on Spotted Hyena-Ant Lion Optimization
    (2023-12) Kumar, P; Kumar, M; Bansal, A
    The parameter extraction of Photovoltaic (PV) cell and module is a necessary to simulate and evaluate the performance of the PV system. The parameter extraction is a complex and challenging task due to its non-linear nature. Researchers are used several metaheuristic algorithms to solve the non-linear problem of parameter extraction. However, the demand for most accurate and reliable methods is increasing to get precise estimation of parameters. In this paper, a novel hybrid optimization algorithm is proposed based on the Spotted-Hyena optimization (SHO) and Ant Lion Optimization (ALO). The hybrid method is called as Spotted Hyena – Ant Lion (SH-AL) optimization. The optimization algorithm is applied in two stages. In stage 1, essential parameters are identified and extracted using SHO and passed to stage 2. In stage 2, identified parameters are optimized using ALO for accurate model of PV cell. Different type of PV cells such as thin film, mono and multi crystalline are examined under various irradiance conditions to extract the parameters. The proposed algorithm is validated by comparing the results with other algorithms and proposed algorithm is proved its superiority.
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    Realization of a green-emitting pyrosilicate structured Er3+-activated Y2Si2O7 phosphor: a systematic study of opto-electronic characteristics and thermal stability for lighting applications
    (2024-05) Kumar, P; Singh, D; Singh, S; Kumar, H; Kumar, R
    A series of green-emitting Y2−xSi2O7:xEr3+ phosphors (x = 1–7 mol%) have been successfully synthesized using a straightforward gel-combustion method facilitated by urea. X-ray diffraction analysis provided specific patterns for samples, confirming a consistent triclinic phase across erbium-doped structures compared to undoped structures. Studies using TEM and EDX were conducted to identify the surface related characteristics and chemical composition of the synthesized nanophosphor, respectively. The band gap was determined to be 5.55 eV and 5.80 eV for the host material and optimal sample, respectively. The primary peak of excitation, observed at 379 nm, represents the highly sensitive electric dipole transition from the 4 I15/2 state to the 4 G11/2 level, suggesting that the prepared phosphors could effectively absorb NUV light for activation. The PL profiles of Y2−xSi2O7:xEr3+ (x = 1–7 mol%) phosphors demonstrate characteristic emissions at 409 nm (2 H9/2 / 4 I15/2), 522 nm (2 H11/2 / 4 I15/2), 553 nm (4 S3/2 / 4 I15/2) and 662 nm (4 F9/2 / 4 I15/2). In accordance with Dexter's theory, luminescence quenching observed at a concentration of 4 mol% Er3+ is attributed to dipole-quadrupole interactions. The optimal sample demonstrates excellent thermal stability, indicated by its luminescence at different temperatures and activation energy of 0.2641 eV. Additionally, the CIE, color purity and CCT values of the fabricated nanomaterials make it ideal for use in lighting applications.
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    Recent Trends in the Design, Synthesis and Biomedical Applications of Covalent Organic Frameworks
    (2022-12) Kaur, G; Kumar, D; Kumar, P
    The most recent and advanced class of crystalline and permeable compounds are covalent organic frameworks (COFs). Due to their exceptional qualities, such as their porous structure, high surface area, strong chemical and thermal stabilities, low density, good water stability, luminescent nature, and so on, COFs have seen remarkable growth over the past ten years. COFs have been successfully researched for a number of applications based on these characteristics. The current state of COFs has been reported in this study, with particular attention paid to their design, topology, synthesis, and a variety of biological applications, including drug delivery systems, photodynamic and photothermal therapy, biosensing, bioimaging, etc. Moreover, several miscellaneous applications, such as catalysis, gas storage and separation, photocatalysis, sensors, solar cells, supercapacitors, and 3D printers, have also been explored. It is significant that we have examined current research on COFs with a focus on the biological applications, which are infrequently covered in the literature. Descriptions of the difficulties and prospective outcomes have also been given.
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    Remediation of toluidine blue O dye from aqueous solution using surface functionalized magnetite nanoparticles
    (2024) Jangra, A; Kumar, R; Singh, D; Kumar, H; Kumar, J; Kumar, P; Kumar, S
    In the current study, tannic acid-functionalized iron oxide nanoparticles have been synthesized using a cost-effective co-pre cipitation method and subsequently characterized using various instrumentation techniques such as Fourier transform infrared spectroscopy, X-ray diffractometer, field emission scanning electron microscopy, and thermal gravimetric analysis. Further, these surface-modified magnetite nanoparticles have been used for the adsorption of toluidine dye from an aqueous solution. The adsorption process was accompanied using batch procedure, and influences of several factors such as adsorbent dose, contact time, pH, temperature, and initial concentration of adsorbate were inspected concurrently. The maximum adsorp tion capacity of tannic acid-functionalized magnetite nanoparticles was found to be 50.68 mg/g. The adsorption process was observed to follow the Temkin isotherm model, whereas the kinetic study was well described by pseudo-second order. The thermodynamic study revealed the adsorption process to be endothermic and spontaneous in nature with a high degree of freedom between adsorbent and adsorbate. Therefore, the study indicated that the tannic acid-functionalized magnetite nano particles have promising adsorption capability and can be used as an excellent adsorbent for the removal of toluidine blue O dye from the aqueous solution.
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    Ydj1 interaction at nucleotide-binding-domain of yeast Ssa1 impacts Hsp90 collaboration andclient maturation
    (2022-11) Gaur, D; Kumar, N; Ghosh, A; Singh, P; Kumar, P; Guleria, J; Kaur, S; Malik, N
    Hsp90constitutes one of the major chaperone machinery in the cell. The Hsp70 assists Hsp90inits client maturation though the underlying basis of the Hsp70 role remains to be explored. In the present study, using S. cerevisiae strain expressing Ssa1 as sole Ssa Hsp70, weidentified novel mutations in the nucleotide-binding domain of yeast Ssa1 Hsp70 (Ssa1-T175N andSsa1-D158N)that adversely affect the maturation of Hsp90 clients v-Src andSte11. The identified Ssa1 amino acids critical for Hsp90 function were also found to be conserved across species such as in E.coli DnaK and the constitutive Hsp70 isoform (HspA8) in humans. These mutations are distal to the C-terminus of Hsp70, that primarily mediates Hsp90 interaction through the bridge protein Sti1, and proximal to Ydj1 (Hsp40 co chaperone of Hsp70 family) binding region. Intriguingly, we found that the bridge protein Sti1 is critical for cellular viability in cells expressing Ssa1-T175N (A1-T175N) or Ssa1 D158N(A1-D158N)assoleSsaHsp70.Thegrowthdefectwasspecific forsti1Δ,as deletion of none of the other Hsp90 co-chaperones showed lethality in A1-T175N or A1-D158N. Mass-spectrometry based whole proteome analysis of A1-T175N cells lacking Sti1 showed an altered abundance of various kinases and transcription factors suggesting compromised Hsp90activity. Further proteomic analysis showed that pathways involved in signaling, sig nal transduction, and protein phosphorylation are markedly downregulated in the A1-T175N upon repressing Sti1 expression using doxycycline regulatable promoter. In contrast to Ssa1, the homologous mutations in Ssa4 (Ssa4-T175N/D158N), the stress inducible Hsp70 isoform, supported cell growth even in the absence of Sti1. Overall, our data suggest that Ydj1 competes with Hsp90 for binding to Hsp70, and thus regulates Hsp90 interaction with the nucleotide-binding domain of Hsp70. The study thus provides new insight into the Hsp70-mediated regulation of Hsp90 and broadens our understanding of the intricate com plexities of the Hsp70-Hsp90 network.
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