Phenotypic expression of blast resistance gene Pi54 is not affected by its chromosomal position

This is a novel report in which chromosomal position of the rice blast resistance gene Pi54 was not found to affect significantly the resistance phenotype or morphological traits. Blast disease caused by Magnaporthe oryzae is a serious constraint in rice production at global level. Pi54 gene imparts resistance against M. oryzae. Three different transgenic lines containing Pi54 and its orthologue Pi54rh were shown to be resistant to different races of M. oryzae. To determine the chromosomal location of Pi54 gene in transgenic lines, inverse PCR was performed. Our analysis showed that in two transgenic lines, Pi54 gene was integrated on chromosomes 6 and 10 at 12.94 and 22.30 Mb, respectively. Similarly, Pi54rh allele was integrated on chromosome 1 at 16.25 Mb. The Pi54 gene present on chromosome 6 was located in a non-coding region whereas in the other TP-Pi54 line, the gene was introgressed on chromosome 10 in between the coding region of SAP domain gene. The Pi54rh was also located in the non coding region flanked by the retrotransposon genes. These rice lines were evaluated for eight different traits related to seed and plant morphology and agronomic features for two consecutive years. The transgenic lines containing Pi54 gene have higher tiller number, grain weight, epicotyl length, and yield compared to the non-transgenic control. Multivariate correlation analysis shows that blast resistance was positively correlated with the number of tillers; thousand grain weight and epicotyl length. These results will facilitate precise utilization of Pi54 gene and its orthologue in breeding programs for the development of rice cultivars with broad spectrum and durable resistance to M. oryzae.

Talc based exopolysaccharides formulation enhancing growth and production of Hellianthus annuus under saline conditions

Stress tolerating strain of Pseudomonas aeruginosa PF07 possessing plant growth promoting activity was screened for the production of exopolysaccharides (EPS). EPS production was monitored in the cell free culture supernatant (CFCS) and extracted EPS was further purified by thin layer chromatography. EPS producing cells were taken to design talc based formulation and its efficacy was checked on oilseed crop sunflower (Hellianthus annuus), under in vivo saline conditions (soil irrigated with 125 mM of saline water). Application of bioformulation significantly enhanced the yield and growth attributes of the plant in comparison to control (untreated seeds) under stress and non—stress conditions. Germination rate, plant length, dry weight and seed weight increased remarkably. The above findings suggest the application and benefits of utilizing EPS formulation in boosting early seedling emergence, enhancing plant growth parameters, increasing seed weight and mitigating stress in saline affected regions. Such bioformulation may enhance RAS/RT (Root Adhering Soil to Root Tissue ratio), texture of the soil, increase porosity, improve uptake of nutrients, and hence may be considered as commercially important formulation for renovation of stressed sites and enhancing plant growth.

Addressing Antimicrobial Resistance in Dentistry

Background

Antimicrobial agents are life saving drugs which are used in management of various life threatening infections but irrational use of antibiotics have led to resurgence of multidrug resistant bacteria which are associated with global increase in mortality due to various infections. Dentists are one among important health care personnel who prescribe antibiotics routinely to treat various oral infections.

Objectives

To summarise the evidence of antimicrobial resistance (AMR) encountered in dental practice, discuss factors associated with it and suggest measures to prevent antimicrobial resistance in dentistry.

Methodology

Articles were identified by searching in electronic data bases such as PubMed, Medline, Embase, Google Scholar and Cochrane data bases using key words like antibiotics, antimicrobial resistance, and antibiotic resistance in dentistry. The articles fulfilling the objectives were included.

Results and Conclusions

Dentists also contribute significantly to the global burden of antimicrobial resistance due to irrational use of antibiotics. Antibiotic stewardship is essential to prevent antimicrobial resistance in dental practice and hence there is an urgent need to educate not only dentists but general public as well. The article describes the gravity of the AMR and the importance of prudent use of antibiotics is discussed.

Co-expression of recombinant human CYP2C9 with human cytochrome P450 reductase in protease deficient S. cerevisiae strain at a higher scale yields an enzyme of higher specific activity

Cytochrome P450 (CYP450) isozymes play an important role in the study of drug metabolism and drug discovery. A number of reports are available that describe recombinant expression of CYP450 isozymes. In this paper, human CYP2C9 and human cytochrome P450 reductase cDNAs were cloned and expressed in Premas proprietary yeast episomal and integrative vectors respectively under the influence of GAL1 promoter. Yeast cells were grown and induced at optimal parameters to make microsomal membranes. Isolated microsomal membranes were analyzed for CYP2C9 and cytochrome P450 reductase activity, CYP2C9 content and inhibition properties. We report heterologous expression of human CYP2C9 along with human cytochrome P450 reductase in protease deficient S. cerevisiae at a 5 litre scale resulting in high yields (8-10 nmols/litre) of enzyme with higher specific activity (2-3 fold higher). This yields a superior enzyme and makes it amenable to miniaturization of screening assays with concomitant lowering of costs.

Activin signaling functions upstream of Gbb to regulate synaptic growth at the Drosophila neuromuscular junction

Activins are members of the TGF-ss superfamily of secreted growth factors that control a diverse array of processes in vertebrates including endocrine function, cell proliferation, differentiation, immune response and wound repair. In Drosophila, the Activin ligand Dawdle (Daw) has been shown to regulate several aspects of neuronal development such as embryonic axonal pathfinding, neuroblast proliferation in the larval brain and growth cone motility in the visual system. Here we identify a novel role for Activin signaling in regulating synaptic growth at the larval neuromuscular junction (NMJ). Mutants for Daw, the Activin type I receptor Baboon (Babo), and the signal transducer dSmad2, display reduced NMJ size suggesting that Daw utilizes a canonical Activin signal-transduction pathway in this context. Additionally, loss of Daw/Babo activity affects microtubule stability, axonal transport and distribution of Futsch, the Drosophila microtubule associated protein 1B (MAP1B) homolog. We find that Babo signaling is required postsynaptically in the muscle, in contrast to the well-characterized retrograde BMP/Gbb signal that is required for synaptic growth and function in presynaptic cells. Finally, we show that the Daw/Babo pathway acts upstream of gbb, and is involved in maintenance of muscle gbb expression, suggesting that Activins regulate NMJ growth by modulating BMP activity through transcriptional regulation of ligand expression.

Anorexia nervosa: an Indian perspective

Anorexia nervosa is a condition thought to be associated with the western culture. However, the recent publication of a case series from Asia suggests that it is a syndrome related to a changing culture. We present a detailed clinical form of this syndrome based on descriptive analysis of 2 cases of anorexia nervosa. Both these patients were adolescent, school-going girls from middle socioeconomic class of urban background. They were pre-morbidly non-obese and did not have any pressures to pursue slimness for beauty. However, there was an identifiable psychosocial stressor as a precipitant in both of them. Both the patients had symptoms of refusal to eat followed by weight loss. We could not identify any risk factor in our patients for anorexia nervosa. Our report illustrates the differences in developmental and psychodynamic issues related to the development of anorexia nervosa, though the clinical symptoms may be similar.

Synthesis and antifilarial evaluation of N1,Nn- xylofuranosylated diaminoalkanes

A series of N(1),N(n)-xylofuranosylated diaminoalkanes (3-9 and 11-18) has been synthesized either by reductive amination of deoxy xylouloses (2a, 2b) with amines followed by one pot reduction with NaBH(4) or NaCNBH(3); or by 1,4-conjugate addition of amines to glycosyl olefinic esters (10a, 10b). The compounds were screened for their interference with filarial worms' glutathione metabolism, a potential target for chemotherapeutic attack. Interestingly, these compounds affected intracellular glutathione, gamma-glutamyl cysteine synthetase, glutathione reductase and glutathione-S-transferase(s) of bovine filarial worms to varying degrees. Some of the compounds though effected the motility and MTT reduction potential of filarial worms Brugia malayi, however, little microfilaricidal and macrofilaricidal were noted with compounds at 50mg/kg oral dose. Compounds 6, 16 and 17 were evaluated also for in vivo activity.

Regulation of BMP and Activin Signaling in Drosophila

Cytokines of the TGF-beta superfamily act through an evolutionarily conserved signaling pathway to elicit a diverse range of biological responses in vertebrates as well as invertebrates. Drosophila has proved to be a powerful system to unravel the profound complexities underlying the regulation of this superficially simple signaling system for two reasons--the availability of sophisticated genetic tools and the restricted number of core signaling components compared to vertebrates. A BMP signaling pathway in Drosophila that regulates growth, differentiation and morphogenesis of the embryo and the larva has been extensively characterized. This work has provided major insights into how gradients of secreted proteins can be established and maintained in vivo, allowing a single ligand to induce multiple cell fates rather than function as an on-off switch. More recently, an activin signaling pathway has also been delineated that is required for growth and neuronal function during development. This review provides an overview of TGF-beta signaling in Drosophila with emphasis on the extensive modulation of signaling activity both within and outside the cell, that enables ligands to trigger specific and context-dependent effects.

Anorexia nervosa with binge eating: a case report

Anorexia nervosa is regarded a s a typical culture bound syndrome, and its existence is negligible in nonwestern countries due to protective biological and socio-cultural factors. Most of the cases reported from nonwestern countries are atypical in presentation with lack of body image disturbances. Recent studies showed that anorexia nervosa is no more culture bound, in fact it is a "culture change syndrome" due to westernization and no differences are seen in the phenomenology of anorexia nervosa between the two cultures. We report a typical case of anorexia nervosa of binge eating and purging type associated with body dysmorphophobia in an adolescent girl.

A new Smurf in the village

TGF-beta signaling is modulated by Smurfs, E3-ubiquitin ligases that selectively target the receptors and Smad proteins for degradation. New evidence from Drosophila suggests that Smurfs regulate the amplitude and the duration of the cellular response to signaling in vivo.

The transcription factor Schnurri plays a dual role in mediating Dpp signaling during embryogenesis

Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embryonic patterning and cell fate specification in Drosophila. Dpp signaling triggers nuclear accumulation of the Smads Mad and Medea, which affect gene expression through two distinct mechanisms: direct activation of target genes and relief of repression by the nuclear protein Brinker (Brk). The zinc-finger transcription factor Schnurri (Shn) has been implicated as a co-factor for Mad, based on its DNA-binding ability and evidence of signaling dependent interactions between the two proteins. A key question is whether Shn contributes to both repression of brk as well as to activation of target genes. We find that during embryogenesis, brk expression is derepressed in shn mutants. However, while Mad is essential for Dpp-mediated repression of brk, the requirement for shn is stage specific. Analysis of brk; shn double mutants reveals that upregulation of brk does not account for all aspects of the shn mutant phenotype. Several Dpp target genes are expressed at intermediate levels in double mutant embryos, demonstrating that shn also provides a brk-independent positive input to gene activation. We find that Shn-mediated relief of brk repression establishes broad domains of gene activation, while the brk-independent input from Shn is crucial for defining the precise limits and levels of Dpp target gene expression in the embryo.

Mapping of hiv-1 Gag epitopes recognized by polyclonal antibodies using gene-fragment phage display system

Phage display has emerged as a powerful technique for mapping epitopes recognised by monoclonal and polyclonal antibodies. We have recently developed a simple gene-fragment phage display system and have shown its utility in mapping epitope recognised by a monoclonal antibody. In the present study, we have employed this system in mapping epitopes recognised by polyclonal antibodies raised against HIV-1 capsid protein, p24 which is derived from proteolytic cleavage of Gag polyprotein. HIV-1 gag DNA was fragmented by DNase I and the fragments (50-250 bp) were cloned into gene-fragment phage display vector to construct a library of phages displaying peptides. This phage library was used for affinity selection of phages displaying epitopes recognised by rabbit anti-p24 polyclonal antibodies. Selected phages contained sequences from two discrete regions of p24, demonstrating the presence of two antigenic regions. The DNA sequences encoding these regions were also cloned and expressed as GST fusion proteins. The immunoreactivity of these epitopes as GST fusion proteins, or as phage-displayed peptides, was comparable in ELISA system using same anti-p24 polyclonal antibodies. The results indicate that the gene-fragment based phage display system can be used efficiently to identify epitopes recognised by polyclonal antibodies, and phage displayed epitopes can be directly employed in ELISA to detect antibodies.

Gag-derived proteins of HIV-1 isolates from Indian patients: cloning, expression, and purification of p17 of B- and C-subtypes

A simple and efficient method for expression in Escherichia coli and purification of matrix protein, p17, of human immunodeficiency virus type 1 (HIV-1) of both B- and C-subtypes is described. DNA sequences encoding p17 of B- and C-subtype were cloned from respective gag sequences. The gag sequences were obtained by PCR amplification using DNA extracted from peripheral blood lymphocytes of an HIV-1 infected patient from India. A T7-promoter-based expression system was optimized for expression of p17 in soluble form. p17 (B- and C-subtype) was purified to near homogeneity using conventional chromatographic techniques. Purification of p17 (C-subtype) is described for the first time with yield of 7.7 mg from a 1-liter culture. The yield of p17 (B-subtype) is 14.7 mg from a 1-liter culture, which is severalfold better than that reported earlier. N-terminal sequencing and CD spectra of the purified proteins, p17B and p17C, show that the proteins are properly processed and well-folded. The immunoreactivity of both types of p17 to sera from HIV-infected individuals is comparable.

schnurri is required for dpp-dependent patterning of the Drosophila wing

The BMP-related ligand Decapentaplegic (Dpp) has a well-characterized role in pattern formation during Drosophila embryogenesis and in larval development. Previous work has shown that transcription of Dpp-responsive genes requires the activity of the BMP-specific Smad, Mothers against dpp (Mad). In this study we investigated the role of the zinc finger transcription factor Schnurri (Shn) in mediating the nuclear response to Dpp during adult patterning. Using clonal analysis, we show that wing imaginal disc cells mutant for shn fail to transcribe the genes spalt, optomotor blind, vestigial, and Dad, that are known to be induced by dpp signaling. shn clones also ectopically express brinker, a gene that is downregulated in response to dpp, thus implicating Shn in both activation and repression of Dpp target genes. We demonstrate that loss of shn activity affects anterior-posterior patterning and cell proliferation in the wing blade, in a manner that reflects the graded requirement for Dpp in these processes. Furthermore, we find that shn is expressed in the pupal wing and plays a distinct role in mediating dpp-dependent vein differentiation at this stage. The absence of shn activity results in defects that are similar in nature and severity to those caused by elimination of Mad, suggesting that Shn has an essential role in dpp signal transduction in the developing wing. Our data are consistent with a model in which Shn acts as a cofactor for Mad.

The zinc finger protein schnurri acts as a Smad partner in mediating the transcriptional response to decapentaplegic

In Drosophila, a BMP-related ligand Decapentaplegic (Dpp) is essential for cell fate specification during embryogenesis and in imaginal disc development. Dpp signaling culminates in the phosphorylation and nuclear translocation of Mothers against dpp (Mad), a receptor-specific Smad that can bind DNA and regulate the transcription of Dpp-responsive genes. Genetic analysis has implicated Schnurri (Shn), a zinc finger protein that shares homology with mammalian transcription factors, in the Dpp signal transduction pathway. However, a direct role for Shn in regulating the transcriptional response to Dpp has not been demonstrated. In this study we show that Shn acts as a DNA-binding Mad cofactor in the nuclear response to Dpp. Shn can bind DNA in a sequence-specific manner and recognizes sites within a well-characterized Dpp-responsive promoter element, the B enhancer of the Ultrabithorax (Ubx) gene. The Shn-binding sites are relevant for in vivo expression, since mutations in these sites affect the ability of the enhancer to respond to Dpp. Furthermore we find that Shn and Mad can interact directly through discrete domains. To examine the relative contribution of the two proteins in the regulation of endogenous Dpp target genes we developed a cell culture assay and show that Shn and Mad act synergistically to induce transcription. Our results suggest that cooperative interactions between these two transcription factors could play an important role in the regulation of Dpp target genes. This is the first evidence that Dpp/BMP signaling in flies requires the direct interaction of Mad with a partner transcription factor.

Gag-derived proteins of HIV-1 isolates from Indian patients: cloning, expression, and purification of p24 of B- and C-subtypes

A simple and efficient method for hyperexpression in Escherichia coli and purification of capsid protein, p24, of human immunodeficiency virus type 1 (HIV-1) of both B- and C-subtypes is described. DNA-encoding p24 of C-subtype was cloned from C-subtype gag sequence which was obtained by PCR amplification using DNA extracted from peripheral blood mononuclear lymphocytes (PBMLs) of an HIV-1-infected patient from India. DNA-encoding p24B protein was amplified directly by two-step PCR using genomic DNA obtained from PBMLs of an HIV-infected individual. A T7 promoter-based expression system was optimized for hyperexpression of p24 in the soluble form. Both p24 (B- and C-subtype) were purified to near homogeneity using conventional chromatographic techniques. Purification of p24 (C subtype) was described for the first time with yield of 53 mg from 1 liter of culture. The yield of p24 (B-subtype) was 67 mg from 1 liter of culture, which was severalfold better than reported earlier. The immunoreactivity of both types of p24 to sera from HIV-infected individuals was comparable. This report describes a simple, highly efficient, and reproducible method for obtaining large quantities of highly pure p24 of both B- and C-subtype, which can be used for structural, biochemical, and immunological characterization and, eventually, for diagnostic and prognostic applications.

Identification of maverick, a novel member of the TGF-beta superfamily in Drosophila

The transforming growth factor-beta (TGF-beta) superfamily of structurally related ligands regulates essential signaling pathways that control many aspects of cell behavior in organisms across the phylogenetic spectrum. Here we report the identification of maverick (mav), a gene that encodes a new member of the TGF-beta superfamily in Drosophila. Phylogenetic analysis and sequence comparison suggest that Mav cannot be easily assigned to any one sub-family, since it is equally related to BMP, activin and TGF-beta ligands. mav maps to the fourth chromosome and is expressed throughout development. In situ hybridization experiments reveal the presence of maternally derived mav transcript in precellular blastoderm embryos. Later in development, mav is expressed in a dynamic pattern in the developing gut, both in endodermal and visceral mesodermal cells. In adult females, high levels of mav mRNA are present in late stage egg chambers.

Factors associated with slow disease progression in macaques immunized with an adenovirus-simian immunodeficiency virus (SIV) envelope priming-gp120 boosting regimen and challenged vaginally with SIVmac251

Rhesus macaques were immunized with a combination vaccine regimen consisting of adenovirus type 5 host range mutant-simian immunodeficiency virus envelope (Ad5hr-SIVenv) recombinant priming and boosting with native SIV gp120. Upon intravaginal challenge with SIVmac251, both persistently and transiently viremic animals were observed (S. L. Buge, E. Richardson, S. Alipanah, P. Markham, S. Cheng, N. Kalyan, C. J. Miller, M. Lubeck, S. Udem, J. Eldridge, and M. Robert-Guroff, J. Virol. 71:8531-8541, 1997). Long-term follow-up of the persistently viremic immunized macaques, which displayed significantly reduced viral burdens during the first 18 weeks postchallenge compared to controls, has now shown that one of four became a slow progressor, clearing virus from plasma and remaining asymptomatic with stable CD4 counts for 134 weeks postchallenge. Reboosting of the transiently viremic macaques did not reactivate latent virus. Rechallenge with two sequential SIVmac251 intravaginal exposures again resulted in partial protection of one of two immunized macaques, manifested by viral clearance and stable CD4 counts. No single immune parameter was associated with partial protection. Development of a strong antibody response capable of neutralizing a primary SIVmac251 isolate together with SIV-specific cytotoxic T lymphocytes were implicated, while CD8(+) T-cell antiviral activity and mucosal immune responses were not associated with delayed disease progression. Our data show that even a third immunization with the same Ad5hr-SIVenv recombinant can elicit significant immune responses to the inserted gene product, suggesting that preexisting Ad antibodies may not preclude effective immunization. Further, the partial protection against a virulent, pathogenic SIV challenge observed in two of six macaques immunized with a vaccine regimen based solely on the viral envelope indicates that this vectored-vaccine approach has promise and that multicomponent vaccines based in the same system merit further investigation.

Simplified gene-fragment phage display system for epitope mapping

We describe a simple and efficient system for epitope mapping by cloning random gene fragments into a specially designed gIIIp-based phage display vector. DNA encoding the antigen of interest is PCR-amplified and partially digested with DNaseI to generate 50-150-bp-long fragments, which are polished with T4 DNA polymerase and dephosphorylated. These fragments are cloned at the 5' end of the gIII after linearizing the vector with SmaI/SrfI, and the ligation is carried out in the presence of restriction enzyme SrfI. The restriction enzyme in the ligation reaction recuts the self-ligated vector but not the recombinants, since ligation with foreign fragments destroys the enzyme recognition site. Dephosphorylation of inserts prevents their chimerization and ensures ligation of single insert per vector molecule. Thus, using the above strategy, which prevents self-ligation of both the insert and the vector, the overall cloning efficiency and, thereby the library size, is improved more than 10-fold compared to the standard blunt-end, ligation-based methods for making similar libraries. The library is further enriched by a single-step infection of E. coli by phages obtained from primary transformants. This step eliminates all the phages that carry insert that are not in-frame with gIIIp and therefore do not display gIIIp. We have shown the utility of the above system in constructing a glutathione-S-transferase (GST) gene-fragment library in phages and identifying the epitope recognized by a monoclonal antibody against GST.