153 research outputs found
Molecular and Cellular Plant Reproduction
No full textPlant reproduction is essential not only for producing offspring but also for increasing crop quality and yield. Moreover, plant reproduction entails complex growth and developmental processes, which provide a variety of opportunities for elucidating fundamental principles in biology. The combinational employment of molecular genetic approaches and emerging technologies, such as florescence-based imaging techniques and next generation sequencing, has led to important progresses in plant reproduction using model plants, crops, and trees. This e-book compiles 31 articles, including 1 hypothesis and theory, 4 perspectives, 12 reviews, and 14 original research papers. We hope that this E-book will draw attention of all plant biologists to exciting advances in the field of plant reproduction and help solve remaining challenging questions in the future. We wish to express our appreciation to all the authors, reviewers, and the Frontiers editorial office for their excellent contributions that made the publication of this e-book possible
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The Role of Chloroplast Localized Small Heat Shock Proteins in Singlet Oxygen Induced Chloroplast Stress
No full textPlants are sessile organisms and thus must acclimate to changes in their surrounding environment to survive. Plants first sense these changes through alterations in photochemistry and reactive oxygen species (ROS) generation in their chloroplasts. A consequence of these alterations is the production of singlet oxygen (1O2), which then elicits a coordinated retrograde response to the nucleus to enact changes in photochemistry back in the chloroplast. Small heat shock proteins are ~100 amino acid long proteins that are currently thought to associate with unfolded proteins to prevent their degradation. Plants are the only organisms that possess organelle targeted small heat shock proteins (sHsps), but the roles of sHsps localizing to the chloroplast are not clear. To further understand the roles of these sHsps and other chloroplast protective mechanisms, we used the Arabodpsis thaliana plastid ferrochelatase 2 (fc2) mutant. Using a reverse genetics approach in the fc2 background, we have shown that chloroplast localized sHsps protect seedlings from cell death under moderate light stress, as well as protecting plants from excess light stress. Knowing how individual chloroplasts communicate and mitigate stress can not only help us further understand interorganelle signaling, but can also provide insight into photosynthetic flux and inform future improvements of crop engineering and farming practices
A study on entrepreneurial awareness among women graduates and post graduates among Tamilnadu, India
No full textFic domain catalyzed adenylylation: Insight provided by the structural analysis of the type IV secretion system effector BepA
No full textNumerous bacterial pathogens subvert cellular functions of eukaryotic host cells by the injection of effector proteins via dedicated secretion systems. The type IV secretion system (T4SS) effector protein BepA from Bartonella henselae is composed of an N-terminal Fic domain and a C-terminal BID domain, the latter being responsible for T4SS-mediated translocation into host cells. A proteolysis resistant fragment (residues 10 to 302) that includes the Fic domain shows auto-adenylylation activity and adenylyl transfer onto Hela cell extract proteins as demonstrated by autoradiography upon incubation with alpha-[(32)P]-ATP. Its crystal structure, determined to 2.9 A resolution by the SeMet-SAD method, exhibits the canonical Fic fold including the HPFxxGNGRxxR signature motif with several elaborations in loop regions and an additional beta-rich domain at the C-terminus. Upon crystal soaking with ATP/Mg(2+), additional electron density indicated the presence of a PP(i)/Mg(2+) moiety, the side product of the adenylylation reaction, in the anion binding nest of the signature motif. Based on this information and that of the recent structure of IbpA(Fic2) in complex with the eukaryotic target protein Cdc42, we present a detailed model for the ternary complex of Fic with the two substrates, ATP/Mg(2+) and target tyrosine. The model is consistent with an in-line nucleophilic attack of the deprotonated side-chain hydroxyl group onto the alpha-phosphorus of the nucleotide to accomplish AMP transfer. Furthermore, a general, sequence independent mechanism of target positioning through antiparallel beta-strand interactions between enzyme and target is suggested
EFFICACY OF TRIDHAM AND 1,2,3,4,6-PENTA-O-GALLOYL-β-D-GLUCOSE IN REVERSING LIPID PEROXIDATION LEVELS AND MITOCHONDRIAL ANTIOXIDANT STATUS IN 7,12-DIMETHYLBENZENEANTHRACENE (DMBA) INDUCED BREAST CANCER IN SPRAGUE-DAWLEY RATS
Get PDFObjective: To determine the effect of Tridham (TD) and 1,2,3,4,6-penta-O-galloyl-β-d-glucose(PGG) on lipid peroxidation levels and mitochondrial antioxidants status in experimental mammary carcinoma.Methods: Elaecoarpus ganitrus (fruits), Terminalia chebula (seed coats), Prosopis cineraria (leaves), adult female albino rats of Sprague-Dawley strain weighing 170–190 g and 7,12-dimethylbenzeneanthracene (DMBA) were used for this study. Group I control rats, Group II rats mammary carcinoma induced with DMBA (25 mg in 1 ml olive oil) by gastric intubation. Group III, IV and V DMBA induced rats were treated with TD (400 mg/kg. b. wt/day), PGG (30 mg/kg. b. wt/day) and standard drug, Cyclophosphamide (30 mg/kg. b. wt/day), respectively for 48 d by gastric intubation. Group VI and VII rats served as TD and PGG treated controls, respectively for 48 d by gastric intubation. At the end of the experimental period, the rats were anaesthetized and sacrificed. Mammary glands were isolated and used for biochemical assays and histopathological evaluation.Results: In rats with cancer, the lipid peroxide levels (LPO) were significantly increased and mitochondrial antioxidant levels were decreased. Treatment with TD and PGG decreased LPO levels and increased mitochondrial antioxidant status in mammary carcinoma bearing rats. Histopathological analysis also confirmed the therapeutic effect of TD and PGG. No significant adverse effect was observed in sole drug treated group of rats.Conclusion: TD and PGG have definite therapeutic effect in experimental mammary carcinoma and inhibit growth of cancer cells by restoring mitochondrial antioxidant status and energy metabolism to normal states
A Study on Prospects and Challenges of Woman Entrepreneurs in Erode District of Tamil Nadu
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Evolution and Genetic Dissection of Two RNA-Dependent Processes in Brassicaceae
No full textThe important role RNA plays in regulating and stabilizing genomes has garnered increased attention since the finding that the majority of the human genome is transcribed (1). However, determining which transcriptional products function in these roles, and which are transcriptional noise, has been challenging. A potential genomic watermark of loci that encode functional RNA is sequence conservation among related species, but the non-coding RNAs that have been characterized have highlighted the relaxed evolutionary constraints of functionally important non-coding RNAs. In some cases, the transcription of certain classes of non-coding RNAs are not in dispute, yet their functional importance remains elusive. To overcome these challenges researchers have begun to expand characterization of non-coding RNAs using a comparative framework, thereby connecting sequence conservation with functional conservation. In this dissertation, I expound on these solutions and use them to show the power of comparative evolutionary approaches when studying non-coding RNAs. First, I show the utility of CRISPR/Cas9 genome editing in generating mutants that permit the clear functional characterization of a long non-coding RNA locus whose identity was drawn into question because of lack of sequence conservation in critical domains. Then I describe a transformation method for the obligate outcrosser, Capsella grandiflora, that expands the genetic resources of the Brassicaceae available for comparative evolutionary analyses in the study of non-coding RNAs. Finally, I use a comparative approach to elucidate the spectrum of impacts resulting from alterations to the RNA-directed DNA Methylation (RdDM) pathway in three related species. More specifically, I probe the contributions of RdDM in mediating genomic conflicts during seed development. In sum, I demonstrate that the study of RNAs benefits from a multi-species approach, particularly when those species can be readily transformed
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Analysis of Magnaporthe Oryzae Homologs of Histoplasma Capsulatum RYP Genes
No full textThe ascomycete fungus Magnaporthe oryzae, causative agent of rice blast disease, poses a threat to global food security, destroying enough rice to feed 60 million people each year. Characterization of the host-pathogen interaction between rice and M. oryzae is critical, as better understanding of the system may lead to better disease control strategies. The sequenced genome and repertoire of molecular tools available have made M. oryzae an ideal model system for understanding general plant-pathogen interactions as well. The objective of this dissertation was to characterize the M. oryzae homologs of Histoplasma capsulatum RYP (Required for Yeast Phase) genes that are required for transition to the parasitic phase. H. capsulatum is a human pathogen that undergoes a dimorphic switch from filamentous to yeast cell growth at 37°C, the host body temperature. Four H. capsulatum RYP genes were identified in a forward genetic screen to identify genes required for entry into the yeast phase. RYP1 is a member of the Gti1_Pac2 family, which contains previously characterized regulators of dimorphic switching. RYP2 and RYP3 are homologs of vosA and velB, members of the Velvet family, best characterized in Aspergillus nidulans, where they coordinate morphological differentiation with secondary metabolism. RYP4 is a zinc binuclear cluster protein, a main class in the zinc finger transcription factor family. Deletion of the M. oryzae RYP1 homolog, RIG1 (Required for Infectious Growth), resulted in a non-pathogenic mutant on susceptible rice cultivars, even upon removal of the host penetration barrier. Δrig1 was blocked in the transition to infectious hyphal growth, similar to H. capsulatum ryp1, which could not transition to the yeast phase. Deletion mutants of M. oryzae RYP2, RYP3, and RYP4 homologs were similar to the wild type in somatic growth and pathogenicity indicating that although RIG1 is a pathogenicity factor conserved in plant and animal pathogens, such conservation does not apply to all of the RYP pathogenicity genes identified in H. capsulatum. Δrig1 is the first M. oryzae mutant known to be blocked in production of primary infection hyphae. Overall, the study suggests limited parallels exist in phase transition of fungal pathogens of plants and animals
Structural investigation into recombinant eye lens aquaporin (AQP0) and the effector proteins (BEPS) from "Bartonella henselae"
Get PDFAbstract Chapter IA: Co-axial association of recombinant eye lens aquaporin AQP0:
Aquaporin-0 (AQP0) is the major membrane protein present in the vertebrate eye lenses.
It has been proposed that AQP0 tetramers mediate contact between membranes of
adjacent lens fiber cells, which would be consistent with the extraordinarily narrow intercellular
space. Indeed, octamer formation with purified AQP0 in solution was observed
by native gel electrophoresis and analytical ultracentrifugation methods. We obtained 3D
crystals of AQP0 that diffract to 7.0 Å resolution and molecular replacement was
performed using the recently determined 3D structure of AQP0 from native source. The
result shows that, within the cubic lattice, tetramers (point symmetry 42) are associated
head-to-head. There are no direct octamer-octamer contacts and the crystal integrity is
most probably maintained by detergent belts surrounding the membrane protein. Within
the octamer, extracellular loops A and C interdigitate at the center and the perimeter of
the octamer, respectively. The octamer formation has been compared with the AQP0
structure derived from 2D crystals using electron diffraction. Intriguingly, the mutual
orientation of tetramers within the octamer is significantly different to that previously
reported for 2D crystals. Clearly, the low resolution of the X-ray data permits only a
comparison of the oligomeric arrangement. The interactions observed in the looselypacked
3D crystals presented here possibly represent the in vivo association mode
between AQP0 tetramers from juxtaposed membranes in the eye lens.
Abstract Chapter II: Structural studies on the effector proteins (Beps) of the VirB-Type IV secretion system in Bartonella henselae:
Type IV transporters are one of the five major families of transporters that are capable of
exporting virulence factors across the membranes of pathogenic bacteria. Members of the
Type IV secretion system (T4SS) share structural homologies but they display diversity
in the nature of the substrates that they transport. T4SS are multicomponent transporters
of Gram-negative bacteria with functions as delivery of effector proteins into eukaryotic
target cells in pathogenesis or DNA transfer in bacterial conjugation through the long
pilus structure (VirB apparatus). Type IV transporters are produced by several bacterial
pathogens. Bartonella henselae is one among the T4SSs which mediates the delivery of
effector proteins into the eukaryotic cell via the process of translocation.
Bartonella henselae is a Gram-negative, arthopod-borne zoonotic pathogen causing a
broad range of clinical manifestations in incidentally infected humans. Transmission to
humans occurs by cat scratch or bite of an infected cat flea causing vasoproliferative
lesions, which result in the formation of tumours in the skin and/or inner organs. In vitro
studies showed that the VirB T4SS of B. henselae mediates most of the virulence
attributes associated with the interaction of B. henselae with human endothelial cells and
they interfere with the signalling network of the host. We have characterized few of the
Bartonella effector proteins (Beps) BepA, B, C and D and their domains of B. henselae
for structural analysis. Crystals were obtained for the truncated version of BepA and it
diffracted to 3.3 Å resolution. Currently, we are in the process of investigating the data
for structural elucidation of the BepA protein. Investigations on other proteins are under
progress.
In this study, we explain the preliminary results obtained from all the constructs and in
detail for the BepA protein. Ultimately, obtaining structural information of these effector
proteins will help us to investigate its functional importance in the eukaryotic host
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