Dormant Forms Research Articles

Macrobenthic Community Structure During Fallow Season in Kole Paddy Fields, Northern Kerala, India

Despite the recognized contribution of benthic fauna in nutrient enhancement, very little information isavailable from Indian paddy fields. This study analyzed the benthic community structure during fallow seasonin Kole paddy fields, a part of Vembanad Kole wetlands (a Ramsar site), Northern Kerala, India. Study area during fallow season was characterized by isolated water patches amidst of terrestrial vegetation (grass). Themacrobenthic fauna belonged to the phyla Annelida, Arthropoda, Mollusca and families Tubificidae, Naididae,Chironomidae, Ceratopogonida, Chaoboridae, Ceratopogonidae, Gyrinidae and Bithynidae. These organismspossessed various survival mechanisms that ensured their survival against dry periods. Insects were the majorbenthic organisms; the habitat fragmentation due to isolated distant water patches during fallow season favoredinsect taxa more due to their active/flight mode of dispersal compared to oligochaetes which are benthiccrawlers. Macrobenthic abundance was less (166±60 ind./m2), attributed to reduced habitable area for benthosdue to habitat desiccation. A decline in abundance was apparent from January to June 2010, the beginning toend of fallow season except in April where the onset of rain after a dry spell made the dry area wet, therebymaking the inactive dormant forms of organisms live, resulting in an increased abundance. Diversity analysis of benthic families revealed that highest richness (d) of 1.235 was in March and diversity (H') of 2.603 was inMarch. No significant correlation emerged between benthic abundance and the measured environmentalparameters, implying that the interaction of biota and physico chemical variables was overridden by some other unmeasured factors

Macrobenthic Community Structure During Fallow Season in Kole Paddy Fields, Northern Kerala, India

Despite the recognized contribution of benthic fauna in nutrient enhancement, very little information is available from Indian paddy fields. This study analyzed the benthic community structure during fallow season in Kole paddy fields, a part of Vembanad Kole wetlands (a Ramsar site), Northern Kerala, India. Study area during fallow season was characterized by isolated water patches amidst of terrestrial vegetation (grass). The macrobenthic fauna belonged to the phyla Annelida, Arthropoda, Mollusca and families Tubificidae, Naididae, Chironomidae, Ceratopogonida, Chaoboridae, Ceratopogonidae, Gyrinidae and Bithynidae. These organisms possessed various survival mechanisms that ensured their survival against dry periods. Insects were the major benthic organisms; the habitat fragmentation due to isolated distant water patches during fallow season favored insect taxa more due to their active/flight mode of dispersal compared to oligochaetes which are benthic crawlers. Macrobenthic abundance was less (166±60 ind./m2), attributed to reduced habitable area for benthos due to habitat desiccation. A decline in abundance was apparent from January to June 2010, the beginning to end of fallow season except in April where the onset of rain after a dry spell made the dry area wet, thereby making the inactive dormant forms of organisms live, resulting in an increased abundance. Diversity analysis of benthic families revealed that highest richness (d) of 1.235 was in March and diversity (H') of 2.603 was in March. No significant correlation emerged between benthic abundance and the measured environmental parameters, implying that the interaction of biota and physico chemical variables was overridden by someother unmeasured factors.

VapC toxin inhibition as a method for prevention of the formation of resting forms of mycobacteria

It has been shown that inactivation of the VapC toxin from the VapВС toxin-antitoxin system prevents mycobacterial cells from transitioning to an ovoid state that meets the criteria of dormancy. The results indicate a potential target for medicines that prevent the development of latent tuberculosis infection and provide a basis to obtain bacterial cells for the testing of compounds that are active towards dormant forms of mycobacteria.

Evolutionary and Functional Analysis of Membrane-Bound NAC Transcription Factor Genes in Soybean.

Functional divergence is thought to be an important evolutionary driving force for the retention of duplicate genes. We reconstructed the evolutionary history of soybean (Glycine max) membrane-bound NAC transcription factor (NTL) genes. NTLs are thought to be components of stress signaling and unique in their requirement for proteolytic cleavage to free them from the membrane. Most of the 15 GmNTL genes appear to have evolved under strong purifying selection. By analyzing the phylogenetic tree and gene synteny, we identified seven duplicate gene pairs generated by the latest whole-genome duplication. The members of each pair were shown to have variously diverged at the transcriptional (organ specificity and responsiveness to stress), posttranscriptional (alternative splicing), and protein (proteolysis-mediated membrane release and transactivation activity) levels. The dormant (full-length protein) and active (protein without a transmembrane motif) forms of one pair of duplicated gene products (GmNTL1/GmNLT11) were each separately constitutively expressed in Arabidopsis (Arabidopsis thaliana). The heteroexpression of active but not dormant forms of these proteins caused improved tolerance to abiotic stresses, suggesting that membrane release was required for their functionality. Arabidopsis carrying the dormant form of GmNTL1 was more tolerant to hydrogen peroxide, which induces its membrane release. Tolerance was not increased in the line carrying dormant GmNTL11, which was not released by hydrogen peroxide treatment. Thus, NTL-release pattern changes may cause phenotypic divergence. It was concluded that a variety of functional divergences contributed to the retention of these GmNTL duplicates.

Structural characterization suggests models for monomeric and dimeric forms of full-length ezrin.

Ezrin is a member of the ERM (ezrin-radixin-moesin) family of proteins that have been conserved through metazoan evolution. These proteins have dormant and active forms, where the latter links the actin cytoskeleton to membranes. ERM proteins have three domains: an N-terminal FERM [band Four-point-one (4.1) ERM] domain comprising three subdomains (F1, F2, and F3); a helical domain; and a C-terminal actin-binding domain. In the dormant form, FERM and C-terminal domains form a stable complex. We have determined crystal structures of the active FERM domain and the dormant FERM:C-terminal domain complex of human ezrin. We observe a bistable array of phenylalanine residues in the core of subdomain F3 that is mobile in the active form and locked in the dormant form. As subdomain F3 is pivotal in binding membrane proteins and phospholipids, these transitions may facilitate activation and signaling. Full-length ezrin forms stable monomers and dimers. We used small-angle X-ray scattering to determine the solution structures of these species. As expected, the monomer shows a globular domain with a protruding helical coiled coil. The dimer shows an elongated dumbbell structure that is twice as long as the monomer. By aligning ERM sequences spanning metazoan evolution, we show that the central helical region is conserved, preserving the heptad repeat. Using this, we have built a dimer model where each monomer forms half of an elongated antiparallel coiled coil with domain-swapped FERM:C-terminal domain complexes at each end. The model suggests that ERM dimers may bind to actin in a parallel fashion.

Spore: Potential of Invaluable Bacterial Wrap

Bacterial Spores are robust and dormant life forms. The enthralling controlling system can maintain the spore dormancy for years yet allow the reappearance into active state within minutes thus provide resistance to the bacterium to heat, freezing, chemicals, radiations and other adverse environments. In spite of being considered as a spoilage and disease cause, Bacterial spores have been emerging as a miracle package. The survivability of bacterial spores under harsh conditions provides various solutions to human needs. Thus bacterial spores are drawing increased interest of the researchers as a solution to get work done under tough conditions. Bacterial spores have been exploited successfully to develop Biological Detection Systems as they can sense environmental changes and respond rapidly. Recently several spore based biosensors have been developed for the detection of different contaminants from different sources. More valued Probiotic Products based on bacterial spores have also been developed as spores can travel through GIT safely due to their resistant to digestive enzymes.Taking advantage of spore survivability, Pest Control Products based on spores are being used for making innovations in pest control. Different strains of Bacillus thuringiensis have been used to protect crops. More recent Bt genes have been expressed in transgenic plants to provide inherent resistance. Bacillus spores also have been exploited for vaccine delivery as a noninvasive and thermostable vaccine delivery system. Bioremediation and Electricity generation is also another applied corner of bacterial spores. This reevaluation highlights the potential of this simpler microbial structure and recent growth in the applied bacterial spore biology. Key-wordsBacterial Spore, Biological detection system, Probiotics, Vaccine delivery, Bioremediation -------------------------------------------------IJLSSR----------------------------------------------INTRODUCTION Under normal conditions, the bacterial cell acquires the nutrients from surroundings that results in an orderly increase of all the chemical constituents of the bacterial cell and the multiplication of the cell is the consequent. During inability of bacteria to acquire nutrients, the bacterial cell loses its ability to reproduce and resultant is the death. However, some bacteria particularly members of Firmicutes, exist in two configurations depending upon the nutrient swing. Under cordial conditions, these bacteria exist as metabolically committed and dividing vegetative cells. Access this article online Quick Response Code: Website:

A new coalescent for seed-bank models

We identify a new natural coalescent structure, which we call the seed-bank coalescent, that describes the gene genealogy of populations under the influence of a strong seed-bank effect, where “dormant forms” of individuals (such as seeds or spores) may jump a significant number of generations before joining the “active” population. Mathematically, our seed-bank coalescent appears as scaling limit in a Wright–Fisher model with geometric seed-bank age structure if the average time of seed dormancy scales with the order of the total population size $N$. This extends earlier results of Kaj, Krone and Lascoux [J. Appl. Probab. 38 (2011) 285–300] who show that the genealogy of a Wright–Fisher model in the presence of a “weak” seed-bank effect is given by a suitably time-changed Kingman coalescent. The qualitatively new feature of the seed-bank coalescent is that ancestral lineages are independently blocked at a certain rate from taking part in coalescence events, thus strongly altering the predictions of classical coalescent models. In particular, the seed-bank coalescent “does not come down from infinity,” and the time to the most recent common ancestor of a sample of size $n$ grows like $\log\log n$. This is in line with the empirical observation that seed-banks drastically increase genetic variability in a population and indicates how they may serve as a buffer against other evolutionary forces such as genetic drift and selection.

Induction of Plasmodium falciparum strain 2300 dormant forms by artemisinin

BACKGROUND The presence of Plasmodium falciparum resistance and decreased efficacy of artemisinin and its derivatives has resulted in the issue of malaria becoming increasingly complex, because there have been no new drugs as artemisinin replacements. The aims of this research were to evaluate in vitro changes in ultrastructural morphology of P. falciparum 2300 strain after exposure to artemisinin. METHODS The research used an experimental design with post test only control group. Cultures of P. falciparum 2300 strain in one control and one mutant group were treated by exposure to artemisinin at IC50 10-7 M for 48 hours. Ultrastructural phenotypic examination of ring, trophozoite and schizont morphology and developmental stage in the control and mutant group were done at 0, 12, 24, 36, 48 hours by making thin blood smears stained with 20% Giemsa for 20 minutes and examined using a microscope light at 1000x magnification. RESULTS Dormant forms occurred after 48 hours of incubation with IC50 10-7 M artemisinin in the control group. In the mutant group, dormant forms, trophozoites with blue cytoplasm and normal schizont developmental stages were seen. Ultrastructural phenotypic morphology at 0, 12, 24, 36, 48 hours showed that in the control group dormant formation already occurred with exposure to IC50 10-7 M, while in the mutant group dormant formation occurred only with exposure to IC50 2.5x10-5 M. CONCLUSION Exposure to artemisinin antimalarials in vitro can cause phenotypic morphological changes of dormancy in P. falciparum Papua 2300 strain.

Surviving forms in antibiotic-treated Pseudomonas aeruginosa

Survival of bacterial populations treated with lethal doses of antibiotics is ensured by the presence of very small numbers of persister cells. Unlike antibiotic-resistant cells, antibiotic tolerance of persisters is not inheritable and reversible. The present work provides evidence supporting the hypothesis of transformation (maturation) of persisters of an opportunistic pathogen Pseudomonas aeruginosa revealed by ciprofloxacin (CF) treatment (25-100 μg/mL) into dormant cystlike cells (CLC) and non-culturable cells (NC), as was described previously for a number. of non-spore-forming bacteria. Subpopulations of type 1 and type 2 persisters, which survived antibiotic treatment and developed into dormant forms, were heterogeneous in their capacity to form colonies or microcolonies upon germination, in resistance to heating at 70 degrees C, and in cell morphology Type 1 persisters, which were formed after 1-month incubation in the stationary-phase cultures in the medium with decreased C and N concentrations, developed in several types of surviving cells, including those similar to CLC in cell morphology. In the course of 1-month incubation of type 2 persisters, which were formed in exponentially growing cultures, other types of surviving cells developed: immature CLC and L-forms. Unlike P. aeruginosa CLC formed in the control post-stationary phase cultures without antibiotic treatment, most of 1-month persisters, especially type 2 ones, were characterized by the loss of colony-forming capacity, probably due to transition into an uncultured state with relatively high numbers of live intact cells (Live/Dead test). Another survival strategy of P. aeruginosa populations was ensured by a minor subpopulation of CF-tolerant and CF-resistant cells able to grow in the form of microcolonies or regular colonies of decreased size in the presence of the antibiotic. The described P. aeruginosa dormant forms may be responsible for persistent forms in bacteria carriers and latent infections and, together with antibiotic-resistant cells, are important as components of test systems to assay the of efficiency of potential pharmaceuticals against resistant infections.

A Bradyzoite is a Bradyzoite is a Bradyzoite?

Bradyzoite forms of Toxoplasma gondii persist in tissue cysts for the lifetime of an infected host and can reactivate to cause clinical disease. It was thought that in vivo bradyzoites within tissue cysts are biologically inactive dormant forms that rarely replicate. Apparently, consensus was wrong.

New aryloxybenzylidene ruthenium chelates - synthesis, reactivity and catalytic performance in ROMP.

New phenoxybenzylidene ruthenium chelates were synthesised from the second generation Grubbs catalysts bearing a triphenylphosphine ligand (or its para-substituted analogues) by metathesis exchange with substituted 2-vinylphenols. The complexes behave like a latent catalyst and are characterized by an improved catalytic behaviour as compared to that of the known analogues, i.e., they exhibit high catalytic inactivity in their dormant forms and a profound increase in activity after activation with HCl. The strong electronic influence of substituents in the chelating ligand on the catalytic activity was demonstrated. The catalytic properties were tested in ROMP of cyclooctadien (COD) and a single selected norbornene derivative.

62 Molecular diagnosis of Pseudomonas aeruginosa infection in culture-negative samples from cystic fibrosis patients

Pseudomonas aeruginosa infection is the main cause of morbidity and mortality in cystic fibrosis (CF) patients. Cultural methods, the gold standard for bacterial detection, are hampered by alginate overproduction and the possible presence of dormant cells. This work aimed at developing a sensitive and specific diagnostic tool capable of detecting P. aeruginosa in culture-negative sputum from CF patients. DNA was extracted with the QIAamp DNA kit after cell spin-down to remove free DNA. Real-time PCR assays targeting 3 species-specific genes, ecfX, gyrB and oprL, were developed using previously designed and new primers. The LOD was determined by spiking different amounts of P. aeruginosa ATCC9027 in a negative sputum sample. The PCR protocol targeting oprL was found to be unreliable, whereas those targeting ecfX and gyrB proved to be effective (LOD 60 cells/ml and 102 cells/ml, respectively). Examination of 33 randomly selected culture-negative samples yielded 6 positive samples from 3 patients: all 6 were ecfX-positive and 2 were positive for ecfX and gyrB. After 1 and 5 months additional samples from patients 1 and 2 were culture-positive; patient 3 received a 4-month antibiotic cycle and 2 months later he resulted still culture-negative and PCR-positive. These findings highlight the value of the Real-time PCRs developed, especially the one targeting ecfX, in diagnosing P. aeruginosa infection in CF samples. Protocol effectiveness was confirmed by the eventual cultural recovery of P. aeruginosa in the two PCR-positive patients, who were found to have chronic CF. Findings also seem to provide further support for a role of dormant forms in recurrent CF infection.

A product of RpfB and RipA joint enzymatic action promotes the resuscitation of dormant mycobacteria

Resuscitation-promoting factor proteins (Rpfs) are known to participate in reactivating the dormant forms of actinobacteria. Structural analysis of the Rpf catalytic domain demonstrates its similarity to lysozyme and to lytic transglycosylases - the groups of enzymes that cleave the β-1,4-glycosidic bond between N-acetylmuramic acid (MurNAc) and GlcNAc, and concomitantly form a 1,6-anhydro ring at the MurNAc residue. Analysis of the products formed from mycobacterial peptidoglycan hydrolysis reactions containing a mixture of RpfB and resuscitation-promoting factor interacting protein (RipA) allowed us to identify the suggested product of their action - N-acetylglucosaminyl-β(1 → 4)-N-glycolyl-1,6-anhydromuramyl-L-alanyl-D-isoglutamate. To identify the role of this resulting product in resuscitation, we used a synthetic 1,6-anhydrodisaccharide-dipeptide, and tested its ability to stimulate resuscitation by using the dormant Mycobacterium smegmatis model. It was found that the disaccharide-dipeptide was the minimal structure capable of resuscitating the dormant mycobacterial cells over the concentration range of 9-100 ng · mL(-1). The current study therefore provides the first insights into the molecular mechanism of resuscitation from dormancy involving a product of RpfB/RipA-mediated peptidoglycan cleavage.

Origins and implications of neglect of G6PD deficiency and primaquine toxicity in Plasmodium vivax malaria

Most of the tens of millions of clinical attacks caused by Plasmodium vivax each year likely originate from dormant liver forms called hypnozoites. We do not systematically attack that reservoir because the only drug available, primaquine, is poorly suited to doing so. Primaquine was licenced for anti-relapse therapy in 1952 and became available despite threatening patients having an inborn deficiency of glucose-6-phosphate dehydrogenase (G6PD) with acute haemolytic anaemia. The standard method for screening G6PD deficiency, the fluorescent spot test, has proved impractical where most malaria patients live. The blind administration of daily primaquine is dangerous, but so too are the relapses invited by withholding treatment. Absent G6PD screening, providers must choose between risking harm by the parasite or its treatment. How did this dilemma escape redress in science, clinical medicine and public health? This review offers critical historic reflection on the neglect of this serious problem in the chemotherapy of P. vivax.

Deciphering the mechanisms against oxidative stress in developing and mature akinetes of the cyanobacterium Aphanizomenon ovalisporum

Cells of filamentous cyanobacteria of the orders Nostocales and Stigonematales can differentiate into dormant forms called akinetes. Akinetes play a key role in the survival, abundance and distribution of the species, contributing an inoculum for their perennial blooms. In the cyanobacterium Aphanizomenon ovalisporum, potassium deficiency triggers the formation of akinetes. Here we present experimental evidence for the production of reactive oxygen species (ROS) during akinete development in response to potassium deficiency. The function of ROS as a primer signal for akinete differentiation was negated. Nevertheless, akinetes acquired protective mechanisms against oxidative damage during their differentiation and maintained them as they matured, giving akinetes advantages enabling survival in harsh conditions.

Identification of potential Mycobacterium tuberculosis topoisomerase I inhibitors: A study against active, dormant and resistant tuberculosis

Mycobacterium tuberculosis (Mtb) topoisomerase I (Topo I), involved in the relaxation of negatively supercoiled DNA, plays an important role in the viability of pathogen Mtb. Being one of the most significant enzymes; it also takes part in crucial biological pathways such as transcription and replication of the pathogen. The present study aims at the development of Mtb Topo I 3D protein structure which in turn was employed for the virtual screening of compound libraries in a process of identification of a hit molecule. The identified hit, hydroxycamptothecin, was active at 6.25μM which was further derivatized synthetically into fifteen novel analogues. Among these, four compounds (3b, 3g, 3h and 3l) emerged to be active displaying IC50 values ranging from 2.9 to 9.3μM against Mtb Topo I and were non-cytotoxic at 25μM. These four compounds also proved their efficacy when tested against active, dormant and resistant forms of Mtb. The most potent inhibitor 3b was screened for in vivo anti-mycobacterial activity using zebrafish model and was found to be more effective when compared to first line anti-tubercular drugs, isoniazid and rifampicin. The binding affinity of this compound towards Mtb Topo I was analyzed by differential scanning fluorimetry which resulted in a positive shift in melting temperature when compared to the native protein thereby proving its stabilization effect over protein.

Increased viability but decreased culturability of Mycobacterium avium subsp. paratuberculosis in macrophages from inflammatory bowel disease patients under Infliximab treatment.

Mycobacterium avium subsp. paratuberculosis (MAP) has long been implicated as a triggering agent in Crohn's disease (CD). In this study, we investigated the growth/persistence of both M. avium subsp. hominissuis (MAH) and MAP, in macrophages from healthy controls (HC), CD and ulcerative colitis patients. For viability assessment, both CFU counts and a pre16SrRNA RNA/DNA ratio assay (for MAP) were used. Phagolysosome fusion was evaluated by immunofluorescence, through analysis of LAMP-1 colocalization with MAP. IBD macrophages were more permissive to MAP survival than HC macrophages (a finding not evident with MAH), but did not support MAP active growth. The lower MAP CFU counts in macrophage cultures associated with Infliximab treatment were not due to increased killing, but possibly to elevation in the proportion of intracellular dormant non-culturable MAP forms, as MAP showed higher viability in those macrophages. Increased MAP viability was not related to lack of phagolysosome maturation. The predominant induction of MAP dormant forms by Infliximab treatment may explain the lack of MAP reactivation during anti-TNF therapy of CD but does not exclude the possibility of MAP recrudescence after termination of therapy.

Study of the effects of the outer space environment on dormant forms of microorganisms, fungi and plants in the ‘Expose-R’ experiment

AbstractInvestigations of the effects of solar radiation combined with the spaceflight factors on biological objects were performed in the «EXPOSE-R» experiment on the outer surface of ISS. After more than 1 year of outer space exposure, the spores of microorganisms and fungi, as well as two species of plant seeds were analysed for viability and the set of biological properties. The experiment provided evidence that not only bacterial and fungal spores but also dormant forms of plants had the capability to survive a long-term exposure to outer space.

Neither the HIV protease inhibitor lopinavir-ritonavir nor the antimicrobial trimethoprim-sulfamethoxazole prevent malaria relapse in plasmodium cynomolgi-infected non-human primates.

Plasmodium vivax malaria causes significant morbidity and mortality worldwide, and only one drug is in clinical use that can kill the hypnozoites that cause P. vivax relapses. HIV and P. vivax malaria geographically overlap in many areas of the world, including South America and Asia. Despite the increasing body of knowledge regarding HIV protease inhibitors (HIV PIs) on P. falciparum malaria, there are no data regarding the effects of these treatments on P. vivax's hypnozoite form and clinical relapses of malaria. We have previously shown that the HIV protease inhibitor lopinavir-ritonavir (LPV-RTV) and the antibiotic trimethoprim sulfamethoxazole (TMP-SMX) inhibit Plasmodium actively dividing liver stages in rodent malarias and in vitro in P. falciparum, but effect against Plasmodium dormant hypnozoite forms remains untested. Separately, although other antifolates have been tested against hypnozoites, the antibiotic trimethoprim sulfamethoxazole, commonly used in HIV infection and exposure management, has not been evaluated for hypnozoite-killing activity. Since Plasmodium cynomolgi is an established animal model for the study of liver stages of malaria as a surrogate for P. vivax infection, we investigated the antimalarial activity of these drugs on Plasmodium cynomolgi relapsing malaria in rhesus macaques. Herein, we demonstrate that neither TMP-SMX nor LPV-RTV kills hypnozoite parasite liver stage forms at the doses tested. Because HIV and malaria geographically overlap, and more patients are being managed for HIV infection and exposure, understanding HIV drug impact on malaria infection is important.

Reviving of the endophytic bacterial community as a putative mechanism of plant resistance

Background From the point of view of systems biology, the plant is considered a super organism that consists of the plant per se and numerous populations of pro- and eukaryotic microbial organisms. Each plant species hosts a genotype-specific core microbiome, dynamically responding to environmental cues, such as soil quality. In the plant endosphere, microbial organisms are an indispensable part of the information processing system, and the plant-endophyte interrelationships result in mutual adjustments through this system. Within the plant tissue, part of the microbiota resides in state called “viable but nonculturable”. Pathogen attack or environmental stress can provoke the dormant forms. The link between reviving of endophytic bacterial populations and plant disease resistance in the endosphere is discussed in this paper.