Search

The length–weight relations of ten fish species representing eight genera and four families and that formed the backbone of the subsistence fishery in the Lakshadweep islands were estimated. These fishes which included four species of tuna [Katsuwonus pelamis (Linnaeus, 1758); Thunnus albacares (Bonnaterre, 1788); Auxis thazard (Lacepède, 1800); Euthynnus affinis (Cantor, 1849)], three species of needlefishes[Ablennes hians (Valenciennes, 1846); Tylosurus crocodilus (Péron et Leseur, 1821); Tylosurus acus melanotus (Bleeker, 1850)], two species of bait fishes [Spratelloides delicatulus (Bennett, 1832); Spratelloides gracilis (Temminck et Schlegel, 1846)], and one species of halfbeak (Hemiramphus archipelagicus Collette et Parin, 1978) contributed to 96% of the total fish landings. The samples were collected from fish landing centers of ten inhabited islands of Lakshadweep from 2015 to 2017. Katsuwonus pelamis showed isometric growth, S. delicatulus and S. gracilis exhibited positive allometry, while negative allometric growth was seen in other species. The coefficient a of the LWR ranged from 0.001 (A. hians) to 0.035 (T. albacares), while b ranged from 2.7 (T. acus melanotus) to 3.4 (S. delicatulus). The results of the presently reported study provide useful biological information on the stock of ten commercially important pelagic fish species supporting the traditional fisheries in Lakshadweep waters.

In plants, AAA-adenosine triphosphatase (ATPase) Cell Division Control Protein 48 (CDC48) uses the force generated through ATP hydrolysis to pull, extract, and unfold ubiquitylated or sumoylated proteins from the membrane, chromatin, or protein complexes. The resulting changes in protein or RNA content are an important means for plants to control protein homeostasis and thereby adapt to shifting environmental conditions. The activity and targeting of CDC48 are controlled by adaptor proteins, of which the plant ubiquitin regulatory X (UBX) domain-containing (PUX) proteins constitute the largest family. Emerging knowledge on the structure and function of PUX proteins highlights that these proteins are versatile factors for plant homeostasis and adaptation that might inspire biotechnological applications.

Characterization of plants with DNA markers is an ideal approach for identification of medicinal plant species as they provide objectively analyzable data for accurate and fast identification. There are many medicinal plants described in ancient literatures that have not been exploited for their medicinal values. A documented treasure of traditional knowledge of Kerala’s Ayurvedic and folklore practices is the ‘Hortus Malabaricus’. Description of various useful medicinal plants and their use as single drug can be seen in this ethnomedicinal compendium. The plants Justicia betonica Linn., Thottea siliquosa Lam., Memecylon edule Roxb., Pajanelia longifolia (Willd) K. Schum.) and Bauhinia accuminata Linn described in Hortus Malabaricus are considered to possess immense therapeutic potentials. As the Ayurveda industry as well as practitioners are facing severe scarcity of required medicinal plants, search for establishing the claimed pharmacologic values of hitherto unexplored plants is to be promoted. For this purpose, their proper identification and authentication is needed as a first step of scientific experiments. The molecular characterization including DNA isolation and sequencing provides fast and accurate identification of medicinal plant species. In this project, the molecular characterization of Justicia betonica, Thottea siliquosa, Memecylon edule, Pajanelia longifolia and Bauhinia accuminata, including DNA isolation and quantification, NCBI-BLAST analysis and DNA sequencing was done. The sequence analysis of Thottea siliquosa, Memecylon edule, Bauhinia accuminata and Justicia betonica by BLASTN (NCBI) is revealed 99 to 100 % nucleotide sequence homology with different database sequences enabling species level confirmation.

The obligate hemiparasitic weed Striga hermonthica grows on cereal roots and presents a severe threat to global food security by causing enormous yield losses, particularly in sub-Saharan Africa. The rapidly increasing Striga seed bank in infested soils provides a major obstacle in controlling this weed. Striga seeds require host-derived strigolactones (SLs) for germination, and corresponding antagonists could be used as germination inhibitors. Recently, we demonstrated that the common detergent Triton X-100 is a specific inhibitor of Striga seed germination by binding noncovalently to its receptor, S. hermonthica HYPO-SENSITIVE TO LIGHT 7 (ShHTL7), without blocking the rice (Oryza sativa) SL receptor DWARF14 (OsD14). Moreover, triazole ureas, the potent covalently binding antagonists of rice SL perception with much higher activity toward OsD14, showed inhibition of Striga but were less specific. Considering that Triton X-100 is not suitable for field application and by combining structural elements of Triton and triazole urea, we developed two hybrid compounds, KK023-N1 and KK023-N2, as potential Striga-specific germination inhibitors. Both compounds blocked the hydrolysis activity of ShHTL7 but did not affect that of OsD14. Binding of KK023-N1 diminished ShHTL7 interaction with S. hermonthica MORE AXILLARY BRANCHING 2, a major component in SL signal transduction, and increased ShHTL7 thermal specificity. Docking studies indicate that KK023-N1 binding is not covalent but is caused by hydrophobic interactions. Finally, in vitro and greenhouse tests revealed specific inhibition of Striga seed germination, which led to a 38% reduction in Striga infestation in pot experiments. These findings reveal that KK023-N1 is a potential candidate for combating Striga and a promising basis for rational design and development of further Striga-specific herbicides.

The present study has carried out with an objective of determining the activity concentrations of two radionuclides namely polonium-210 (210Po) and lead-210 (210Pb) in smoke tobacco products (cigarette, bidi and cigar) and smokeless tobacco products (chewing tobacco and snuff) consumed in Tiruchirappalli District, Tamil Nadu (India) and their annual committed effective dose to tobacco consumers. The concentration of 210Po was always higher than that of 210Pb in all the analyzed tobacco products. It also revealed that 79% of Annual committed effective dose comes from 210Po and about 21% from 210Pb. Maximum concentration (13.2 mBq g−1) of 210Po recorded in cigarette and lowest concentration was observed in snuff (6.4 mBq g−1). The highest mean committed effective dose of 210Po and 210Pb in various tobacco products were found in cigarette followed by bidi, cigar, chewing tobacco and snuff. The study revealed that the tobacco products available in Tiruchirappalli District contain a relatively lower concentration of radionuclides when compared to other regional studies. Since this kind of study in India is fragmentary, the present study has generated a base data for the first time for entire Tiruchirappalli District.

The DNA-binding protein H-NS is a pleiotropic gene regulator in gram-negative bacteria. Through its capacity to sense temperature and other environmental factors, H-NS allows pathogens like Salmonella to adapt their gene expression to their presence inside or outside warm-blooded hosts. To investigate how this sensing mechanism may have evolved to fit different bacterial lifestyles, we compared H-NS orthologs from bacteria that infect humans, plants, and insects, and from bacteria that live on a deep-sea hypothermal vent. The combination of biophysical characterization, high-resolution proton-less nuclear magnetic resonance spectroscopy, and molecular simulations revealed, at an atomistic level, how the same general mechanism was adapted to specific habitats and lifestyles. In particular, we demonstrate how environment-sensing characteristics arise from specifically positioned intra- or intermolecular electrostatic interactions. Our integrative approach clarified the exact modus operandi for H-NS-mediated environmental sensing and suggested that this sensing mechanism resulted from the exaptation of an ancestral protein feature.

Background: Brain tumor initiating cells (BTICs) play a key role in the progression and relapse of the dreadful glioblastoma. Targeting the TLX involved self-renewal mechanism of BITCs may enable us to develop novel therapeutic strategy for glioblastoma. Methods: The function of NR2E (TLX) and its interacting protein-LSD1 in BTICs were characterized by gene knockdown combined with tumor sphere formation assay, cell-growth assay, co-immunoprecipitation and chromatin immunoprecipitation assays. NR2E interacting peptide of LSD1 was identified and confirmed by Amide Hydrogen/Deuterium Exchange and Mass Spectrometry (HDX-MS) and in vitro functional assay with LSD1 fragment deletion mutants. The in vivo function of the peptide was further examined with patient-derived glioblastoma initiating cell xenograft mouse model. Findings: NR2E1 recruits LSD1 to remove the active epigenetic marker H3K4me3 at Pten promoter and repress its expression, thereby promoting BTIC proliferation. LSD1 peptide (L197-211) that locates at the LSD1 SWIRM domain is critical for the interaction between NR2E1 and LSD1. Overexpression of this peptide inhibits BTIC proliferation and brain tumor growth. Interpretation: Our studies show that NR2E1 partners with LSD1 to promote the self-renewal of BTICs. Interference of NR2E1 and LSD1 interaction by peptide L197-211 may be explored as a novel therapeutic strategy for malignant brain tumors. Funding Information: This work was supported by funds from National Natural Science Foundation of China (NSFC) (Grant No. 81773156 to PY and Grant No. 8187232 to YM) and the support of the Ministry of Education of Singapore Academic Research Fund to the Singapore researchers to KS. Declaration of Interests: The authors declare that no competing interest exists. Ethics Approval Statement: The animal experiments were performed under the approval from Animal Experimentation Ethics Committee (AEEC) in the Sixth Affiliated Hospital of Sun Yatsen University.

Karnataka, a state in south India, reported its first case of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection on March 8, 2020, more than a month after the first case was reported in India. We used a combination of contact tracing and genomic epidemiology to trace the spread of SARS-CoV-2 in the state up until May 21, 2020 (1578 cases). We obtained 91 genomes of SARS-CoV-2 which clustered into seven lineages (Pangolin lineages—A, B, B.1, B.1.80, B.1.1, B.4, and B.6). The lineages in Karnataka were known to be circulating in China, Southeast Asia, Iran, Europe and other parts of India and are likely to have been imported into the state both by international and domestic travel. Our sequences grouped into 17 contact clusters and 24 cases with no known contacts. We found 14 of the 17 contact clusters had a single lineage of the virus, consistent with multiple introductions and most (12/17) were contained within a single district, reflecting local spread. In most of the 17 clusters, the index case (12/17) and spreaders (11/17) were symptomatic. Of the 91 sequences, 47 belonged to the B.6 lineage, including eleven of 24 cases with no known contact, indicating ongoing transmission of this lineage in the state. Genomic epidemiology of SARS-CoV-2 in Karnataka suggests multiple introductions of the virus followed by local transmission in parallel with ongoing viral evolution. This is the first study from India combining genomic data with epidemiological information emphasizing the need for an integrated approach to outbreak response.

Karnataka, a state in south India, reported its first case of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) on March 8, 2020, more than a month after the first case was reported in India. We used a combination of contact tracing and genomic epidemiology to trace the spread of SARS-CoV-2 in the state up until May 21, 2020 (1578 cases). We obtained 47 full genomes of SARS-CoV-2 which clustered into six lineages (Pangolin lineages-A, B, B.1, B.1.1, B.4, and B.6). The lineages in Karnataka were known to be circulating in China, Southeast Asia, Iran, Europe and other parts of India and are likely to have been imported into the state both by international and domestic travel. Our sequences grouped into 12 contact clusters and 11 cases with no known contacts. We found nine of the 12 contact clusters had a single lineage of the virus, consistent with multiple introductions and most (8/12) were contained within a single district, consistent with local spread. In most of the twelve clusters, the index case (9/12) and spreaders (8/12) were symptomatic. Of the 47 sequences, 31 belonged to the B/B.6 lineage, including seven of eleven cases with no known contact, this is consistent with the ongoing transmission of this lineage in the state. Genomic epidemiology of SARS-CoV-2 in Karnataka is consistent with multiple introductions of the virus followed by local transmission in parallel with ongoing viral evolution. This is the first study from India combining genomic data with epidemiological information emphasizing the need for an integrated approach to outbreak response.

Inter simple sequence repeat markers were employed for the genotyping of 16 plantain ecotypes. Two different electrophoretic systems namely conventional gel electrophoresis (CVGE) and fully automated high-resolution CGE were used to evaluate the genetic diversity. Comparative analysis indicated that all parameters related to marker informativeness were higher in CGE except polymorphic information content. But genetic diversity parameters like effective number of alleles, Nei's gene diversity (1973) and Shannon's information index showed higher values (1.52 ± 0.12, 0.34 ± 0.05 and 0.52 ± 0.05, respectively) in CVGE as against CGE (1.29 ± 0.04, 0.22 ± 0.02 and 0.38 ± 0.03, respectively) system. The unweighed pair group method with arithmetic averages was used to obtain the dendrogram for both analyses. The results of dendrogram and principal component analysis were found to be consistent in both systems except for some minor disagreements. The clone-specific bands could be used in the identification and development of SCAR markers. Inter simple sequence repeat markers used in this study provided sufficient polymorphism and reproducible banding pattern for evaluating the genetic diversity of different plantain ecotypes. Lack of accuracy and consistency of the CVGE warrants the employment of high-throughput CGE for diversity analysis as it provided better separation of bands with higher resolution.

The DNA-binding protein H-NS is a pleiotropic gene regulator in gram-negative bacteria. Through its capacity to sense temperature and other environmental factors, H-NS allows pathogens like Salmonella to adapt their gene expression, and hence toxicity and biological responses, to their presence inside or outside warm-blooded hosts. To investigate how this sensing mechanism may have evolved to fit different bacterial lifestyles, we compared H-NS orthologs from bacteria that infect humans, plants, and insects, and from bacteria that live on a deep-sea hypothermal vent. The combination of biophysical characterization, high-resolution proton-less NMR spectroscopy and molecular simulations revealed, at an atomistic level, how the same general mechanism was adapted to specific habitats and lifestyles. In particular, we demonstrate how environment-sensing characteristics arise from specifically positioned intra- or intermolecular electrostatic interactions. Our integrative approach clarified the mechanism for H-NS–mediated environmental sensing and suggests that it resulted from the exaptation of an ancestral protein feature.

Made available in DSpace on 2019-10-04T12:37:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-18 Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy Office of Sponsored Research (OSR) National Institutes of Health of USA King Abdullah University of Science and Technology (KAUST) As an environment-dependent pleiotropic gene regulator in Gram-negative bacteria, the H-NS protein is crucial for adaptation and toxicity control of human pathogens such as Salmonella, Vibrio cholerae or enterohaemorrhagic Escherichia coli. Changes in temperature affect the capacity of H-NS to form multimers that condense DNA and restrict gene expression. However, the molecular mechanism through which H-NS senses temperature and other physiochemical parameters remains unclear and controversial. Combining structural, biophysical and computational analyses, we show that human body temperature promotes unfolding of the central dimerization domain, breaking up H-NS multimers. This unfolding event enables an autoinhibitory compact H-NS conformation that blocks DNA binding. Our integrative approach provides the molecular basis for H-NS-mediated environment-sensing and may open new avenues for the control of pathogenic multi-drug resistant bacteria. King Abdullah Univ Sci & Technol, Div Biol & Environm Sci & Engn BESE, Computat Biosci Res Ctr, Thuwal 239556900, Saudi Arabia Univ Vermont, Dept Chem, Burlington, VT 05405 USA Sao Paulo State Univ, Dept Phys IBILCE, Sao Paulo, Brazil King Abdullah Univ Sci & Technol, Imaging & Characterizat Core Lab, Thuwal 239556900, Saudi Arabia King Abdullah Univ Sci & Technol, Computat Biosci Res Ctr, Comp Elect & Math Sci & Engn Div BESE, Thuwal 239556900, Saudi Arabia Univ Leeds, Sch Mol & Cellular Biol, Leeds, W Yorkshire, England King Abdullah Univ Sci & Technol, Div Biol & Environm Sci & Engn, Thuwal 239556900, Saudi Arabia Sao Paulo State Univ, Dept Phys IBILCE, Sao Paulo, Brazil Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy: DE-AC02-05CH11231 Office of Sponsored Research (OSR): URF/1/1976-06 Office of Sponsored Research (OSR): URF/1/1976-04 Office of Sponsored Research (OSR): 3007 National Institutes of Health of USA: 1R01GM129431-01

We developed easy to synthesize and efficient strigolactone analogs with great application potential. Biological activities and receptor binding assays demonstrate the effect of structural modification on the efficacy and specificity of strigolactones., Strigolactones (SLs) are a new class of phytohormones that also act as germination stimulants for root parasitic plants, such as Striga spp., and as branching factors for symbiotic arbuscular mycorrhizal fungi. Sources for natural SLs are very limited. Hence, efficient and simple SL analogs are needed for elucidating SL-related biological processes as well as for agricultural applications. Based on the structure of the non-canonical SL methyl carlactonoate, we developed a new, easy to synthesize series of analogs, termed methyl phenlactonoates (MPs), evaluated their efficacy in exerting different SL functions, and determined their affinity for SL receptors from rice and Striga hermonthica. Most of the MPs showed considerable activity in regulating plant architecture, triggering leaf senescence, and inducing parasitic seed germination. Moreover, some MPs outperformed GR24, a widely used SL analog with a complex structure, in exerting particular SL functions, such as modulating Arabidopsis roots architecture and inhibiting rice tillering. Thus, MPs will help in elucidating the functions of SLs and are promising candidates for agricultural applications. Moreover, MPs demonstrate that slight structural modifications clearly impact the efficiency in exerting particular SL functions, indicating that structural diversity of natural SLs may mirror a functional specificity.

Background: Upto date, the scientific documentation regarding in-vitro antiurolithiatic activity of has been reported, although it has not reported for in-vitro antiurolithiatic activity up till now. Objective: To explore anti-urolithiatic activities of Pavonia lasiopetala leaves extract by utilizing different in-vitro models. Material and Methods: Aqueous extract of Pavonia lasiopetala fresh leaves was prepared and arranged in the different concentrations. Homogenous precipitation method was used to prepare artificial stones such as calcium oxalate and calcium phosphate and semi-permeable membrane of eggs was used as dissolution bags. Dissolution models were incubated in 72 hrs and after that, the entire content in dissolution bags was estimated spectrophotometrically. The inhibitory activity of Pavonia lasiopetala leaves extract on the nucleation of calcium oxalate crystals and the rate of aggregation in calcium oxalate crystals was determined by spectrophotometric assay. Results: In dissolution models, the extract of Pavonia lasiopetala has greater capability to dissolve calcium oxalate while Cystone standard has shown better demineralization for calcium phosphate rather than extract of Pavonia lasiopetala. Cystone exhibited strongly inhibitory action in the nucleation assay rather than aggregation assay. The extract of Pavonia lasiopetala exhibited inhibitory action in both of nucleation and aggregation assays to significant level. Discussion: Correlation between in-vitro and in-vivo studies may be helpful to understand the molecular mechanism of litholysis process and to reveal phytochemicals of the extract responsible for dissolving or disintegrating renal calculi. Conclusion: Pavonia lasiopetala extract exhibited significant in-vitro anti-urolithiatic activity. Keywords: Pavonia lasiopetala, spectrophotometrically, in-vitro antiurolithiatic.

Ubiquitination is a process in which a protein is modified by the covalent attachment of the C-terminal carboxylic acid of ubiquitin (Ub) to the epsilon-amine of lysine or N-terminal methionine residue of a substrate protein or another Ub molecule. Each of the seven internal lysine residues and the N-terminal methionine residue of Ub can be linked to the C-terminus of another Ub moiety to form 8 distinct Ub linkages and the resulting differences in linkage types elicit different Ub signaling pathways. Cellular responses are triggered when proteins containing ubiquitin-binding domains (UBDs) recognize and bind to specific polyUb linkage types. To get more insight into the differences between polyUb chains, all of the seven lysine-linked di-ubiquitin molecules (diUbs) were prepared and used as a model to study their structural conformations in solution using NMR spectroscopy. We report the synthesis of diUb molecules, fully N-15-labeled on the distal (N-terminal) Ub moiety and revealed their structural orientation with respect to the proximal Ub. As expected, the diUb molecules exist in different conformations in solution, with multiple conformations known to exist for K6-, K48-, and K63-linked diUb molecules. These multiple conformations allow structural flexibility in binding with UBDs thereby inducing unique responses. One of the well-known but poorly understood UBD-Ub interaction is the recognition of K6 polyubiquitin by the ubiquitin-associated (UBA) domain of UBXN1 in the BRCA-mediated DNA repair pathway. Using our synthetic N-15-labeled diUbs, we establish here how a C-terminally extended UBA domain of UBXN1 confers specificity to K6 diUb while the non-extended version of the domain does not show any linkage preference. We show that the two distinct conformations of K6 diUb that exist in solution converge into a single conformation upon binding to this extended form of the UBA domain of the UBXN1 protein. It is likely that more of such extended UBA domains exist in nature and can contribute to linkage-specificity in Ub signaling. The isotopically labeled diUb compounds described here and the use of NMR to study their interactions with relevant partner molecules will help accelerate our understanding of Ub signaling pathways.

The maltose-binding protein (MBP) is one of the most frequently used protein tags due to its capacity to stabilize, solubilize and even crystallize recombinant proteins that are fused to it. Given that MBP is thought to be a highly stable monomeric protein with known characteristics, fused passenger proteins are often studied without being cleaved from MBP. Here we report that a commonly used engineered MBP version (mutated to lower its surface entropy) can form interlaced dimers when fused to short protein sequences derived from the focal adhesion kinase (FAK) or the homologous protein tyrosine kinase 2 (PYK2). These MBP dimers still bind maltose and can interconvert with monomeric forms in vitro under standard conditions despite a contact surface of more than 11,000 Å2. We demonstrate that both the mutations in MBP and the fused protein sequences were required for dimer formation. The FAK and PYK2 sequences are less than 40% identical, monomeric, and did not show specific interactions with MBP, suggesting that a variety of sequences can promote this MBP dimerization. MBP dimerization was abrogated by reverting two of the eight mutations introduced in the engineered MBP. Our results provide an extreme example for induced reversible domain-swapping, with implications for protein folding dynamics. Our observations caution that passenger-promoted MBP dimerization might mislead experimental characterization of the fused protein sequences, but also suggest a simple mutation to stop this phenomenon.

Purpose The aim of this laboratory study was to investigate the amount of bacterial destruction through riboflavin mediated photodynamic therapy (PDT) around fixed orthodontic devices by using the two strains of bacteria Streptococcus mutans and Streptococcus sanguinis. Materials and methods A total of 80 metallic brackets were divided into four groups consisting of 20 brackets each. Group-I: riboflavin + LED irradiation; Group-II: riboflavin alone; Group-III: immersion in 0.2 % chlorhexidine gluconate solution and Group-IV: not submitted to any treatment. All metallic brackets were immersed in the standard bacterial solutions and incubated at 48 h. All samples were subjected to MTT assay for microbial cell viability testing after treatment. After 24 h of incubation, biofilms adhered on the mesh of metallic brackets after treatment were assessed by confocal laser microscopy. The total CFU/mL was estimated, and the results were log-transformed (log10) and analyzed using one-way analysis of variance and Tukey-Kramer test. P-value was set to Results The samples from group-IV showed the highest amount of relative biofilm viability compared to any other group while group-I (PDT) showed the least viability of the two bacterial strains studied (p 0.05). The biofilms on the samples from group-II and group-IV were largely viable indicating thick green staining across the mesh of the brackets. Among the group-III samples, there were predominantly dead cells as compared to the live cell staining. A considerable amount of red staining was observed with noticeable less green staining in group-I samples. Conclusion This laboratory investigation revealed that riboflavin mediated PDT significantly reduced the amounts of S. mutans and S. sanguinis around the orthodontic brackets.

The ability of bats to act as reservoir for viruses that are highly pathogenic to humans suggests unique properties and functional characteristics of their immune system. However, the lack of bat specific reagents, in particular antibodies, has limited our knowledge of bat's immunity. Here, we report a panel of cross-reactive antibodies against MHC-II, NK1.1, CD3, CD21, CD27, and immunoglobulin (Ig), that allows flow cytometry analysis of B, T and NK cell populations in two different fruit-eating bat species namely, Pteropus alecto and E. spelaea. Results confirmed predominance of T cells in the spleen and blood of bats, as previously reported by us. However, the percentages of B cells in bone marrow and NK cells in spleen varied greatly between wild caught P. alecto bats and E. spelaea colony bats, which may reflect inherent differences of their immune system or different immune status. Other features of bat B cells were investigated. A significant increase in sIg+ B cell population was observed in the spleen and blood from LPS-injected bats but not from poly I:C-injected bats, supporting T-independent polyclonal B cell activation by LPS. Furthermore, using an in vitro calcium release assay, P. alecto B cells exhibited significant calcium release upon cross-linking of their B cell receptor. Together, this work contributes to improve our knowledge of bat adaptive immunity in particular B cells.

Marine environment is enriched source of heavy minerals associated with radionuclides which are largely responsible for human exposure to radiation. Bay of Bengal is one among the important marine ecosystems in the world because of its high biodiversity. The aim of this work was to generate a comprehensive data on distribution and bioaccumulation of 210Po and 210Pb in marine environment of the Bay of Bengal. For this water and sand samples (10 stations), shellfishes (21 species) and fishes (43 species) were collected and the concentrations of 210Po and 210Pb were measured by radiochemical separation followed by alpha counting method using ZnS(Ag) detector. 210Pb concentration in the marine water (mean: 7.6 ± 3.31 mBq l-1) is always higher than 210Po (mean: 4.1 ± 1.97 mBq l-1). The mean 210Po and 210Pb concentration in sand was 5.2 ± 1.87 and 3.1 ± 1.20 Bq kg-1, respectively; indicating that 210Po concentrations in the sand sample is always higher than that of 210Pb. The concentration of both 210Po and 210Pb depends on grain size of the sand. Surface samples of depth 0-10 cm recorded maximum 210Po (6.37 Bq kg-1) and 210Pb (4.07 Bq kg-1) concentration. The concentrations of 210Po and 210Pb in biota are following decreasing order: Oyster > Clam > Squid > Crab > Prawn > Fish. The committed effective dose rate calculated for shellfish species maintained a higher range of 81.0-281.2 μSv y-1. However, dose transfer rate from fish species fluctuated from 14.4 to 165.6 μSv y-1and this indicated that fish is radiologically safe as compared to shellfish.

The success of bedaquiline as an anti-tubercular agent for the treatment of multidrug-resistant tuberculosis has validated the ATP synthesis pathway and in particular ATP synthase as an attractive target. However, limitations associated with its use in the clinic and the drug–drug interactions with rifampicin have prompted research efforts towards identifying alternative ATP synthesis inhibitors with differentiated mechanisms of action. A biochemical assay was employed to screen AstraZeneca's corporate compound collection to identify the inhibitors of mycobacterial ATP synthesis. The high-throughput screening resulted in the identification of 2,4-diaminoquinazolines as inhibitors of the ATP synthesis pathway. A structure–activity relationship for the quinazolines was established and the knowledge was utilized to morph the quinazoline core into quinoline and pyrazolopyrimidine to expand the scope of chemical diversity. The morphed scaffolds exhibited a 10-fold improvement in enzyme potency and over 100-fold improvement in selectivity against inhibition of mammalian mitochondrial ATP synthesis. These novel compounds were bactericidal and demonstrated growth retardation of Mycobacterium tuberculosis in the acute mouse model of tuberculosis infection.

Summary The human protein arginine methyltransferase NDUFAF7 controls the assembly of the ∼1-MDa mitochondrial complex I (CI; the NADH ubiquinone oxidoreductase) by methylating its subunit NDUFS2. We determined crystal structures of MidA, the Dictyostelium ortholog of NDUFAF7. The MidA catalytic core domain resembles other eukaryotic methyltransferases. However, three large core loops assemble into a regulatory domain that is likely to control ligand selection. Binding of MidA to NDUFS2 is weakened by methylation, suggesting a mechanism for methylation-controlled substrate release. Structural and bioinformatic analyses support that MidA and NDUFAF7 and their role in CI assembly are conserved from bacteria to humans, implying that protein methylation already existed in proteobacteria. In vivo studies confirmed the critical role of the MidA methyltransferase activity for CI assembly, growth, and phototaxis of Dictyostelium . Collectively, our data elucidate the origin of protein arginine methylation and its use by MidA/NDUFAF7 to regulate CI assembly.

The overall bauplan of the tetrapod brain is highly conserved, yet significant variations exist among species in terms of brain size, structural composition and cellular diversity. Understanding processes underlying neural and behavioral development in a wide range of species is important both from an evolutionary developmental perspective as well as for the identification of cell sources with post-developmental neurogenic potential. Here we characterize germinal processes in the brain of Notophthalmus viridescens and Pleurodeles waltl during both development and adulthood. Using a combination of cell tracking tools, including clonal analyses in new transgenic salamander lines we examine the origin of neural stem and progenitor cells found in the adult brain, determine regional variability in cell cycle length of progenitor cells, and show spatio-temporally orchestrated neurogenesis. We analyze how maturation of different brain regions and neuronal subpopulations are linked to the acquisition of complex behaviors, and how these behaviors are altered upon chemical ablation of dopamine neurons. Our data analyzed from an evolutionary perspective reveal both common and species-specific processes in tetrapod brain formation and function.

The mechanism of efflux is a tour-de-force in the bacterial armoury that has thwarted the development of novel antibiotics. We report the discovery of a novel chemical series with potent antibacterial properties that was engineered to overcome efflux liability. Compounds liable to efflux specifically via the Resistance Nodulation and cell Division (RND) pump, AcrAB-TolC were chosen for a hit to lead progression. Using structure-based design, the compounds were optimised to lose their binding to the efflux pump, thereby making them potent on wild-type bacteria. We discovered these compounds to be pro-drugs that require activation in E. coli by specific bacterial nitroreductases NfsA and NfsB. Hit to lead chemistry led to the generation of compounds that were potent on wild-type and multi-drug resistant clinical isolates of E. coli, Shigella spp., and Salmonella spp. These compounds are bactericidal and efficacious in a mouse thigh infection model.

Salamanders exhibit an extraordinary ability among vertebrates to regenerate complex body parts. However, scarce genomic resources have limited our understanding of regeneration in adult salamanders. Here, we present the ~20 Gb genome and transcriptome of the Iberian ribbed newt Pleurodeles waltl, a tractable species suitable for laboratory research. We find that embryonic stem cell-specific miRNAs mir-93b and mir-427/430/302, as well as Harbinger DNA transposons carrying the Myb-like proto-oncogene have expanded dramatically in the Pleurodeles waltl genome and are co-expressed during limb regeneration. Moreover, we find that a family of salamander methyltransferases is expressed specifically in adult appendages. Using CRISPR/Cas9 technology to perturb transcription factors, we demonstrate that, unlike the axolotl, Pax3 is present and necessary for development and that contrary to mammals, muscle regeneration is normal without functional Pax7 gene. Our data provide a foundation for comparative genomic studies that generate models for the uneven distribution of regenerative capacities among vertebrates., The Iberian ribbed newt Pleurodeles waltl has a wide spectrum of regeneration abilities. Here, Elewa et al. sequence its ~20 Gb genome and transcriptome to investigate the molecular features underlying its regenerative capacities.

The Mur ligases play an essential role in the biosynthesis of bacterial peptidoglycan and hence are attractive antibacterial targets. A screen of the AstraZeneca compound library led to the identification of compound A, a pyrazolopyrimidine, as a potent inhibitor of Escherichia coli and Pseudomonas aeruginosa MurC. However, cellular activity against E. coli or P. aeruginosa was not observed. Compound A was active against efflux pump mutants of both strains. Experiments using an E. coli tolC mutant revealed accumulation of the MurC substrate and a decrease in the level of product upon treatment with compound A , indicating inhibition of MurC enzyme in these cells. Such a modulation was not observed in the E. coli wild-type cells. Further, overexpression of MurC in the E. coli tolC mutant led to an increase in the compound A MIC by ≥16-fold, establishing a correlation between MurC inhibition and cellular activity. In addition, estimation of the intracellular compound A level showed an accumulation of the compound over time in the tolC mutant strain. A significant compound A level was not detected in the wild-type E. coli strain even upon treatment with high concentrations of the compound. Therefore, the lack of MIC and absence of MurC inhibition in wild-type E. coli were possibly due to suboptimal compound concentration as a consequence of a high efflux level and/or poor permeativity of compound A.

Enhanced production of manganese peroxidase (MnP) by the mutant Pleurotus ostreatus MTCC 142 was carried out in a solid and submerged fermentation by using an agro-industrial waste (rice bran and wheat bran) under optimized conditions. Among the various substrate combinations examined, rice bran shows the highest MnP activity (273 U/L), when compared with the wheat bran (218 U/L). Maximum MnP (368 U/L) was produced when rice bran (5 g) at 75% moisture (w/v) was used with 1 mL inoculum at pH 4 and 25°C in the presence of 2% (w/v) glucose as a carbon source, 0.2% (w/v) sodium nitrate as a nitrogen source and 4% of (v/v) glycerol as an inducer for MnP production under submerged fermentation. MnP was purified from the culture fluid by using microfiltration (1.2 μm) and ammonium sulphate precipitation followed by ion exchange chromatography. Additionally, the protein content of the recovered supernatant was also noted. The purified MnP was a monomer, which showed a molecular mass of 58 ± kDa as determi...

Type II topoisomerases are well conserved across the bacterial species, and inhibition of DNA gyrase by fluoroquinolones has provided an attractive option for treatment of tuberculosis (TB). However, the emergence of fluoroquinolone-resistant strains of Mycobacterium tuberculosis (Mtb) poses a threat for its sustainability. A scaffold hopping approach using the binding mode of novel bacterial topoisomerase inhibitors (NBTIs) led to the identification of a novel class of benzimidazoles as DNA gyrase inhibitors with potent anti-TB activity. Docking of benzimidazoles to a NBTI bound crystal structure suggested that this class of compound makes key contacts in the enzyme active site similar to the reported NBTIs. This observation was further confirmed through the measurement of DNA gyrase inhibition, and activity against Mtb strains harboring mutations that confer resistance to aminopiperidines based NBTIs and Mtb strains resistant to moxifloxacin. Structure-activity relationship modification at the C-7 position of the left-hand side ring provided further avenue to improve hERG selectivity for this chemical series that has been the major challenges for NBTIs.

DNA gyrase is a clinically validated target for developing drugs against Mycobacterium tuberculosis (Mtb). Despite the promise of fluoroquinolones (FQs) as anti-tuberculosis drugs, the prevalence of pre-existing resistance to FQs is likely to restrict their clinical value. We describe a novel class of N-linked aminopiperidinyl alkyl quinolones and naphthyridones that kills Mtb by inhibiting the DNA gyrase activity. The mechanism of inhibition of DNA gyrase was distinct from the fluoroquinolones, as shown by their ability to inhibit the growth of fluoroquinolone-resistant Mtb. Biochemical studies demonstrated this class to exert its action via single-strand cleavage rather than double-strand cleavage, as seen with fluoroquinolones. The compounds are highly bactericidal against extracellular as well as intracellular Mtb. Lead optimization resulted in the identification of potent compounds with improved oral bioavailability and reduced cardiac ion channel liability. Compounds from this series are efficacious in various murine models of tuberculosis.

SummaryThe chromosome passenger complex (CPC) must relocate from anaphase chromosomes to the cell equator for successful cytokinesis. Although this landmark event requires the mitotic kinesin MKlp2, the spatiotemporal mechanistic basis remains elusive. Here, we show that phosphoregulation of MKlp2 by the mitotic kinase Cdk1/cyclin B1 coordinates proper mitotic transition with CPC relocation. We identified multiple Cdk1/cyclin B1 phosphorylation sites within the stalk and C-terminal tail that inhibit microtubule binding and bundling, oligomerization/clustering, and chromosome targeting of MKlp2. Specifically, inhibition of these abilities by Cdk1/cyclin B1 phosphorylation is essential for proper early mitotic progression. Upon anaphase onset, however, reversal of Cdk1/cyclin B1 phosphorylation promotes MKlp2-CPC complex formation and relocates the CPC from anaphase chromosomes for successful cytokinesis. Thus, we propose that phosphoregulation of MKlp2 by Cdk1/cyclin B1 ensures that activation of MKlp2 kinesin and relocation of the CPC occur at the appropriate time and space for proper mitotic progression and genomic stability.

Scaffold hopping from the thiazolopyridine ureas led to thiazolopyridone ureas with potent antitubercular activity acting through inhibition of DNA GyrB ATPase activity. Structural diversity was introduced, by extension of substituents from the thiazolopyridone N-4 position, to access hydrophobic interactions in the ribose pocket of the ATP binding region of GyrB. Further optimization of hydrogen bond interactions with arginines in site-2 of GyrB active site pocket led to potent inhibition of the enzyme (IC50 2 nM) along with potent cellular activity (MIC=0.1 μM) against Mycobacterium tuberculosis (Mtb). Efficacy was demonstrated in an acute mouse model of tuberculosis on oral administration.

Strychnos potatorum seeds have been utilized for the preparation of adsorbent, surface modified S. potatorum seeds (SMSP), by sulfuric acid treatment with 1:2 ratios of precursor to sulfuric acid. The adsorption process depends on the solution pH, adsorbent dose, contact time, initial Ni(II) ions concentration, and temperature. The adsorption kinetics of Ni(II) ions removal by the SMSP was relatively fast and it reaches the equilibrium at 30min. The maximum removal of Ni(II) ions was observed at an optimum conditions: pH of 5.0, adsorbent dose of 5g/L, contact time of 30min, and at temperature of 30˚C for an initial Ni(II) ions concentration of 100mg/L. In order to investigate the adsorption kinetics for the removal of Ni(II) ions by SMSP, pseudo-first-order and pseudo-secondorder kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits the experimental data better than the pseudo-first-order kinetic model with good coefficient of determination values. Adsorption mechanism was discussed with different models such as intraparticle diffusion, Boyd kinetic, and shrinking core models. It was observed that the adsorption process was controlled by both film and particle diffusion. The effective diffusivity and diffusivity values were estimated from the Boyd kinetic and shrinking core models, respectively. Adsorption isotherm data were tested with the Langmuir, Freundlich, Temkin, and Dubinin‐Radushkevich models. It was observed that the Freundlich model fits the isotherm data better than other isotherm models with good coefficient of determination values. The Freundlich constant “n” was found to be of 3.888g/L which indicates that the adsorption of Ni(II) ions onto the SMSP followed the physical process. The thermodynamic parameters such as change in free energy, enthalpy, and entropy were also calculated. It was found that the adsorption process was spontaneous and exothermic in nature.

A new pyrimidine based Schiff base ligand (HL) and its four complexes of type [MLOAc]·nH2O (Cu(II), 1; Zn(II), 2; Co(II), 3; and Ni(II), 4) have been synthesized and characterized by elemental analysis, MS, 1H-NMR, FT-IR, UV-visible, and ESR techniques. The electronic and ESR spectral data suggested that complexes 1–4 possess square planar geometry. Antimicrobial activities of HL and complexes 1–4 were tested against four bacteria (Staphylococcus aureus, Staphylococcus pneumonia, Salmonella enterica typhi, and Haemophilus influenzae) and two fungal strains (Aspergillus flavus and Aspergillus niger). These results show that complexes 1–4 have good antimicrobial activity compared to HL. The DNA cleavage activity of HL and complexes 1–4 was monitored by the agarose gel electrophoresis method. The antioxidant property of the prepared compounds was assessed by using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. DNA binding properties of HL and complexes 1–4 have been investigated by electronic absorption technique and viscometric measurements.

Similar to other biomolecules such as proteins and nucleic acids, glycans also had a rich history in therapeutic applications.4-6 However, due to their high complexity and structural diversity, glycans were omitted in the last century as DNA-and protein-focused treatments became readily accessible. Nevertheless, the recent development in carbohydrate synthesis and analysis fuelled the interest in glycan-based drug discovery.7 This chapter is mainly focused on two different aspects: (1) a brief description of carbohydrate-based drugs and vaccines currently available on the market for the treatment of various diseases and (2) the possibilities of sulfated marine carbohydrates in drug discovery.

Besides modulating pain, stress, physiological functions, motivation, and reward, the opioid system has been implicated in developmental and adult mammalian neurogenesis and gliogenesis. In adult male songbirds including zebra finches, neurons generated from the ventricular zone (VZ) of the lateral ventricles are incorporated throughout the telencephalon, including the song control nuclei, HVC, and area X. Although the endogenous opioid met-enkephalin is present in neurons adjacent to the VZ and is upregulated in song control regions during singing, it is not known whether the opioid system can modulate adult neurogenesis/gliogenesis in zebra finches. We used quantitative RT-PCR and in situ hybridization to demonstrate that μ- and δ-opioid receptors are expressed by the VZ of adult male zebra finches. Treating cultured VZ cells from male birds with the opioid antagonist naloxone led to an increase in cell proliferation measured by 5-bromo-2-deoxyuridine incorporation, whereas administering met-enkephalin had the opposite effect, compared with saline-treated cultures. Systemically administering naloxone (2.5 mg/kg body wt) to adult male zebra finches for 4 d also led to a significant increase in cell proliferation in the ventral VZ of these birds, compared with saline-treated controls. Our results show that cell proliferation is augmented by naloxone in the VZ adjacent to the anterior commissure, suggesting that the endogenous opioids modulate adult neurogenesis/gliogenesis by inhibiting cell proliferation in songbirds.

Amyloid is the main pathological substrate of Alzheimer's disease (AD) and has been described in leucine-rich repeat kinase 2 (LRRK2) carriers with Parkinson's disease. LRRK2 has been linked with amyloid precursor protein pathways in neurodegeneration. Two common LRRK2 variants, R1398H and N551K, have been shown to be protective in multiple Parkinson's disease cohorts. We hypothesized that R1398H and N551K may be protective in AD. In a case-control study involving 1390 subjects (719 controls and 671 AD cases), R1398H was demonstrated in 16.8% of AD cases compared to 16.7% in controls (odds ratio = 1.01, 95% confidence interval = 0.76–1.34, p = 0.94), whereas N551K was demonstrated in 17.3% of AD cases compared to 17.2% of controls (odds ratio = 1.00, 95% confidence interval = 0.76–1.32, p = 0.98). Overall, these results suggest that LRRK2 R1398H or N551K variants do not appear to modulate the risk of AD.

Problem statement: Human Immunodeficiency Virus-1 (HIV-1) is causative agent of the immune system disease, Acquired Immune Deficiency Syndrome (AIDS). Majority of anti-HIV drugs target reverse transcriptase and protease enzymes. Toxicity and development of multidrug resistant HIV-1 virus strains are the reasons for studying new targets in HIV-1 replication process for identifying novel inhibitor with low toxicity and high activity. Approach: In this study, ROCS software was used to identify the novel HIV-1 Integrase (HIV-1 IN) inhibitor by shape-based virtual screening. The currently used drug raltegravir was used as query molecule. Results: Here five novel molecules were identified, among them Rank 5 molecule was shown to have higher structural and electrostatic similarity to query molecule and this molecule was considered as good inhibitor of HIV-1 IN enzyme. Conclusion: ROCS, EON and FRED effectively identified one active inhibitor of HIV-1 IN among five compounds, which was similar to the query molecule and this study showed that ROCS, EON and FRED can play a vital role in drug discovery projects.

A systematic study on the natural radionuclides such as 210 Po and 210 Pb in the environmental matrices of Point Calimere ecosystem has been undertaken to establish a baseline data on the radiation profile of Point Calimere environment. The environmental samples such as water, sediment and biota (seaweeds, crustaceans, molluscs and fish) have been subjected to analyses. It has been observed that the concentration of 210 Po and 210 Pb in the water samples of Point Calimere to be 0.5 mBq/l and 1.3 mBq/l, respectively. The soft tissues of the organisms accumulated higher 210 Po content while shells and bones contained more 210 Pb. The bivalve molluscs Meretrix casta have been identified to accumulate higher concentration of 210 Po suggesting that they could serve as bio-indicator of radionuclides like 210 Po in the Point Calimere ecosystem. The concentration factor of 210 Po for the biotic components ranged from ∼10 3 to 10 6 while for 210 Pb it ranged from ∼10 3 to 10 5 .

Structure–activity relationship (SAR) exploration on the left-hand side (LHS) of a novel class of bacterial topoisomerase inhibitors led to a significant improvement in the selectivity against hERG cardiac channel binding with concomitant potent antimycobacterial activity. Bulky polar substituents at the C-7 position of the naphthyridone ring did not disturb its positioning between two base pairs of DNA. Further optimization of the polar substituents on the LHS of the naphthyridone ring led to potent antimycobacterial activity (Mtb MIC = 0.06 μM) against Mycobacterium tuberculosis (Mtb). Additionally, this knowledge provided a robust SAR understanding to mitigate the hERG risk. This compound class inhibits Mtb DNA gyrase and retains its antimycobacterial activity against moxifloxacin-resistant strains of Mtb. Finally, we demonstrate in vivo proof of concept in an acute mouse model of TB following oral administration of compound 19.

We describe in vitro anti-Mycobacterium tuberculosis activities of ring-substituted-1H-imidazole-4-carboxylic acid derivatives (1-6), and 3-(2-alkyl-1H-imidazol-4-yl)-propionic acid derivatives (7-13) against drug-sensitive and drug-resistant M. tuberculosis H37Rv strains. The most effective analogues, 2f (R=R(1)=c-C(5)H(9)), and 2h (R=R(1)=c-C(6)H(11)) have produced90% inhibition at a concentration of6.25 microg/ml in the drug-sensitive screen. Upon further evaluation against drug-resistant strains, both analogues 2f and 2h produced an MIC value of 25.0 microg/ml. The observation of significant anti-tuberculosis activity in some of these analogues describes the discovery of novel ring-substituted-1H-imidazole-4-carboxylic acid ethyl esters as a new class of anti-tuberculosis agents.

The widespread emergence of Plasmodium falciparum (Pf) strains resistant to frontline agents has fuelled the search for fast-acting agents with novel mechanism of action. Here, we report the discovery and optimization of novel antimalarial compounds, the triaminopyrimidines (TAPs), which emerged from a phenotypic screen against the blood stages of Pf. The clinical candidate (compound 12) is efficacious in a mouse model of Pf malaria with an ED99, The emergence of resistant Plasmodium strains fuels the search for new antimalarials. Here, the authors present a new class of potent antimalarial compounds, the triaminopyrimidines, that display low toxicity and long half-life in animal models.

Neural stem cells (NSCs) give rise to neurons in the adult brain and are possible targets in regenerative therapies. In vitro cultures of NSCs as neurospheres have been established from cells isolated from diverse species. Newts are exceptional regenerators among vertebrates. These animals are able to efficiently replace neurons following ablation of those by activation and subsequent differentiation of NSCs. Here we describe the method for isolating and culturing of NSCs from the newt brain both during self-renewing and differentiating conditions. Newt NSC culture provides a useful tool for functional studies of NSC fate with the potential of resulting in novel regenerative strategies.

Organisms need to adapt to the ecological constraints in their habitat. How specific processes reflect such adaptations are difficult to model experimentally. We tested whether environmental shifts in oxygen tension lead to events in the adult newt brain that share features with processes occurring during neuronal regeneration under normoxia. By experimental simulation of varying oxygen concentrations, we show that hypoxia followed by re-oxygenation lead to neuronal death and hallmarks of an injury response, including activation of neural stem cells ultimately leading to neurogenesis. Neural stem cells accumulate reactive oxygen species (ROS) during re-oxygenation and inhibition of ROS biosynthesis counteracts their proliferation as well as neurogenesis. Importantly, regeneration of dopamine neurons under normoxia also depends on ROS-production. These data demonstrate a role for ROS-production in neurogenesis in newts and suggest that this role may have been recruited to the capacity to replace lost neurons in the brain of an adult vertebrate. DOI: http://dx.doi.org/10.7554/eLife.08422.001, eLife digest During the winter, red-spotted newts remain active in water that is covered by ice. The oxygen levels under the ice tend to drop and so the newts adjust their metabolism to cope with these conditions. However, when oxygen levels return to normal, this may result in the newts producing larger amounts of chemically reactive molecules called reactive oxygen species (ROS). These molecules form naturally as a by-product of oxygen metabolism, but in high quantities they can damage cells and tissues. It has been proposed that red-spotted newts and other animals that experience periods of low oxygen may have evolved processes to repair such damage. Unlike us, red-spotted newts are able to replace nerve cells in the brain that have died or been injured. This regeneration is fuelled by stem cells called ependymoglia cells, which divide to produce new nerve cells. Here, Hameed et al. investigated whether the return of oxygen to normal levels after a period of low oxygen can damage nerve cells in the newts, and whether this is followed by regeneration. The experiments show that nerve cells in the newt brain do indeed die when oxygen levels return to normal. Also, the brain activates an injury response that triggers the ependymoglia cells to divide. During this process, the ependymoglia cells accumulate ROS and their ability to divide is impaired if the production of ROS is blocked. The replacement of injured brain cells in normal oxygen conditions also depends on increased ROS levels. Together, Hameed et al.'s findings demonstrate a key role for ROS production in controlling the regeneration of damaged nerve cells in the red-spotted newt. A future challenge is to identify the genes that control the survival and activation of ependymoglia cells in response to increased ROS levels in the brain. DOI: http://dx.doi.org/10.7554/eLife.08422.002

The bacterial peptidoglycan biosynthesis pathway provides multiple targets for antibacterials, as proven by the clinical success of β-lactam and glycopeptide classes of antibiotics. The Mur ligases play an essential role in the biosynthesis of the peptidoglycan building block, N-acetyl-muramic acid-pentapeptide. MurC, the first of four Mur ligases, ligates l-alanine to UDP-N-acetylmuramic acid, initiating the synthesis of pentapeptide precursor. Therefore, inhibiting the MurC enzyme should result in bacterial cell death. Herein, we report a novel class of pyrazolopyrimidines with subnanomolar potency against both Escherichia coli and Pseudomonas aeruginosa MurC enzymes, which demonstrates a concomitant bactericidal activity against efflux-deficient strains. Radio-labeled precursor incorporation showed these compounds selectively inhibited peptidoglycan biosynthesis, and genetic studies confirmed the target of pyrazolopyrimidines to be MurC. In the presence of permeability enhancers such as colistin, pyrazolopyrimidines exhibited low micromolar MIC against the wild-type bacteria, thereby, indicating permeability and efflux as major challenges for this chemical series. Our studies provide biochemical and genetic evidence to support the essentiality of MurC and serve to validate the attractiveness of target for antibacterial discovery.