scholarly journals Bacterial Cells Carrying Synthetic Dual-Function Operon Survived Starvation

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Yuki Matsumoto ◽  
Yoichiro Ito ◽  
Saburo Tsuru ◽  
Bei-Wen Ying ◽  
Tetsuya Yomo
Keyword(s):  
Population Dynamics ◽  
Cell Growth ◽  
Nutritional Status ◽  
Bacterial Genome ◽  
Dual Function ◽  
Bacterial Cells ◽  
Stable States ◽  
External Perturbations ◽  
Bistable Structure ◽  
Synthetic Operon

A synthetic dual-function operon with a bistable structure was designed and successfully integrated into the bacterial genome. Bistability was generated by the mutual inhibitory structure comprised of the promotersPtetandPlacand the repressors LacI and TetR. Dual function essential for cell growth was introduced by replacing the genes (i.e., hisCandleuB) encoding proteins involved in the biosynthesis of histidine and leucine from their native chromosomal locations to the synthetic operon. Both colony formation and population dynamics of the cells carrying this operon showed that the cells survived starvation and the newly formed population transited between the two stable states, representing the inducedhisCandleuBlevels, in accordance with the nutritional status. The results strongly suggested that the synthetic design of proto-operons sensitive to external perturbations is practical and functional in native cells.

scholarly journals Enhanced Arsenic Accumulation in Engineered Bacterial Cells Expressing ArsR

2004 ◽  
Vol 70 (8) ◽  
pp. 4582-4587 ◽  
Author(s):  
Jan Kostal ◽  
Rosanna Yang ◽  
Cindy H. Wu ◽  
Ashok Mulchandani ◽  
Wilfred Chen
Keyword(s):  
Cell Growth ◽  
Environmental Protection Agency ◽  
Arsenic Removal ◽  
Fusion Partner ◽  
Resting Cells ◽  
Bacterial Cells ◽  
High Affinity ◽  
Affinity Ligand ◽  
Arsenic Accumulation ◽  
Severe Reduction

ABSTRACT The metalloregulatory protein ArsR, which offers high affinity and selectivity toward arsenite, was overexpressed in Escherichia coli in an attempt to increase the bioaccumulation of arsenic. Overproduction of ArsR resulted in elevated levels of arsenite bioaccumulation but also a severe reduction in cell growth. Incorporation of an elastin-like polypeptide as the fusion partner to ArsR (ELP153AR) improved cell growth by twofold without compromising the ability to accumulate arsenite. Resting cells overexpressing ELP153AR accumulated 5- and 60-fold-higher levels of arsenate and arsenite than control cells without ArsR overexpression. Conversely, no significant improvement in Cd2+ or Zn2+ accumulation was observed, validating the specificity of ArsR. The high affinity of ArsR allowed 100% removal of 50 ppb of arsenite from contaminated water with these engineered cells, providing a technology useful to comply with the newly approved U.S. Environmental Protection Agency limit of 10 ppb. These results open up the possibility of using cells overexpressing ArsR as an inexpensive, high-affinity ligand for arsenic removal from contaminated drinking and ground water.

scholarly journals Coexistence of Wolbachia with Buchnera aphidicola and a Secondary Symbiont in the Aphid Cinara cedri

2004 ◽  
Vol 186 (19) ◽  
pp. 6626-6633 ◽  
Author(s):  
Laura Gómez-Valero ◽  
Mario Soriano-Navarro ◽  
Vicente Pérez-Brocal ◽  
Abdelaziz Heddi ◽  
Andrés Moya ◽  
...  
Keyword(s):  
Bacterial Genome ◽  
Pcr Amplification ◽  
Bacterial Cells ◽  
Buchnera Aphidicola ◽  
Rdna Genes ◽  
16S Ribosomal Dna ◽  
Secondary Symbiont ◽  
Rdna Sequences ◽  
16S Rdna Sequences

ABSTRACT Intracellular symbiosis is very common in the insect world. For the aphid Cinara cedri, we have identified by electron microscopy three symbiotic bacteria that can be characterized by their different sizes, morphologies, and electrodensities. PCR amplification and sequencing of the 16S ribosomal DNA (rDNA) genes showed that, in addition to harboring Buchnera aphidicola, the primary endosymbiont of aphids, C. cedri harbors a secondary symbiont (S symbiont) that was previously found to be associated with aphids (PASS, or R type) and an α-proteobacterium that belongs to the Wolbachia genus. Using in situ hybridization with specific bacterial probes designed for symbiont 16S rDNA sequences, we have shown that Wolbachia was represented by only a few minute bacteria surrounding the S symbionts. Moreover, the observed B. aphidicola and the S symbionts had similar sizes and were housed in separate specific bacterial cells, the bacteriocytes. Interestingly, in contrast to the case for all aphids examined thus far, the S symbionts were shown to occupy a similarly sized or even larger bacteriocyte space than B. aphidicola. These findings, along with the facts that C. cedri harbors the B. aphidicola strain with the smallest bacterial genome and that the S symbionts infect all Cinara spp. analyzed so far, suggest the possibility of bacterial replacement in these species.

Evolution of Sociality and Nonlinear Population Dynamics

2020 ◽  
pp. 100-113
Author(s):  
Daniel Oro
Keyword(s):  
Population Dynamics ◽  
Cultural Transmission ◽  
Life Histories ◽  
Minimum Size ◽  
Stable States ◽  
Individual Fitness ◽  
Social Species ◽  
Strong Source ◽  
Adaptive Behaviours ◽  
Threshold Setting

Sociality appears in many life histories during evolution. Some eusocial bees show evolutionary reversions to solitary behaviour, and populations of the same species can be solitary or social, likely depending on local environmental features. Social species need a minimum size to perform adaptive behaviours, such as the search for resources, which is crucial especially under perturbations. This minimum size may become a threshold, setting a phase transition for separating two stable states, from disorganized and maladaptive to organized and adaptive, which also shows hysteresis. The chapter also explores evolution via facilitation or cooperation (e.g. social information) under the theoretical framework of multilevel selection, by which there is likely an effect of the social group’s genes on individual fitness. Perturbations appear as a strong source of evolutionary processes. In humans, warfare acts as a very powerful selective pressure for competition between groups and thus for cooperation. Sociality has also many costs, such as a higher risk for the spread of infectious disease, the appearance of traps by social haunting philopatry, stronger aggression and competition, and a higher risk of being attacked by predators. Finally, the evolution of cultures is explored; optimization of social learning, social copying, and cultural transmission may have nonlinear consequences for population dynamics.

scholarly journals Effect of Laser Irradiation on Cell Function and Its Implications in Raman Spectroscopy

2018 ◽  
Vol 84 (8) ◽  
pp. e02508-17 ◽  
Author(s):  
Xiaofei Yuan ◽  
Yanqing Song ◽  
Yizhi Song ◽  
Jiabao Xu ◽  
Yinhu Wu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Cell Growth ◽  
Single Cell ◽  
Laser Irradiation ◽  
Living Cells ◽  
Growth Characteristics ◽  
Single Cell Level ◽  
Bacterial Cells ◽  
Cell Level ◽  
Gram Negative

ABSTRACTLasers are instrumental in advanced bioimaging and Raman spectroscopy. However, they are also well known for their destructive effects on living organisms, leading to concerns about the adverse effects of laser technologies. To implement Raman spectroscopy for cell analysis and manipulation, such as Raman-activated cell sorting, it is crucial to identify nondestructive conditions for living cells. Here, we evaluated quantitatively the effect of 532-nm laser irradiation on bacterial cell fate and growth at the single-cell level. Using a purpose-built microfluidic platform, we were able to quantify the growth characteristics, i.e., specific growth rates and lag times of individual cells, as well as the survival rate of a population in conjunction with Raman spectroscopy. Representative Gram-negative and Gram-positive species show similar trends in response to a laser irradiation dose. Laser irradiation could compromise the physiological function of cells, and the degree of destruction is both dose and strain dependent, ranging from reduced cell growth to a complete loss of cell metabolic activity and finally to physical disintegration. Gram-positive bacterial cells are more susceptible than Gram-negative bacterial strains to irradiation-induced damage. By directly correlating Raman acquisition with single-cell growth characteristics, we provide evidence of nondestructive characteristics of Raman spectroscopy on individual bacterial cells. However, while strong Raman signals can be obtained without causing cell death, the variety of responses from different strains and from individual cells justifies careful evaluation of Raman acquisition conditions if cell viability is critical.IMPORTANCEIn Raman spectroscopy, the use of powerful monochromatic light in laser-based systems facilitates the detection of inherently weak signals. This allows environmentally and clinically relevant microorganisms to be measured at the single-cell level. The significance of being able to perform Raman measurement is that, unlike label-based fluorescence techniques, it provides a “fingerprint” that is specific to the identity and state of any (unlabeled) sample. Thus, it has emerged as a powerful method for studying living cells under physiological and environmental conditions. However, the laser's high power also has the potential to kill bacteria, which leads to concerns. The research presented here is a quantitative evaluation that provides a generic platform and methodology to evaluate the effects of laser irradiation on individual bacterial cells. Furthermore, it illustrates this by determining the conditions required to nondestructively measure the spectra of representative bacteria from several different groups.

Ultrasensitive fluorometric determination of iron(iii) and inositol hexaphosphate in cancerous and bacterial cells by using carbon dots with bright yellow fluorescence

The Analyst ◽  
2019 ◽  
Vol 144 (16) ◽  
pp. 5010-5021 ◽  
Author(s):  
Fangchao Cui ◽  
Jiadi Sun ◽  
Xingxing Yang ◽  
Jian Ji ◽  
Fuwei Pi ◽  
...  
Keyword(s):  
Living Cells ◽  
Dual Function ◽  
Bacterial Cells ◽  
Trace Detection ◽  
Ferric Ions ◽  
Fluorometric Determination ◽  
Inositol Hexaphosphate ◽  
Yellow Fluorescence ◽  
Bright Yellow

An ON–OFF–ON dual-function fluorescent nanoprobe is described for the trace detection of ferric ions and inositol hexaphosphate (IP6) in living cells.

scholarly journals Dual Function of Pancreatic Endoplasmic Reticulum Kinase in Tumor Cell Growth Arrest and Survival

2008 ◽  
Vol 68 (9) ◽  
pp. 3260-3268 ◽  
Author(s):  
Aparna C. Ranganathan ◽  
Shishir Ojha ◽  
Antonis Kourtidis ◽  
Douglas S. Conklin ◽  
Julio A. Aguirre-Ghiso
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Growth ◽  
Tumor Cell ◽  
Growth Arrest ◽  
Dual Function ◽  
Tumor Cell Growth ◽  
Cell Growth Arrest

Actuated Bistable Jumping Structures

2010 ◽  
Vol 77 (3) ◽  
Author(s):  
Matthew Santer
Keyword(s):  
High Frequency ◽  
Adaptive Systems ◽  
High Energy ◽  
Low Energy ◽  
Stable States ◽  
Dynamic Transition ◽  
Bistable Structure ◽  
Energy Stable

The design and analysis of a fully actuated adaptive bistable structure is presented. This structure releases energy at a high frequency, which in consequence causes it to jump. Such structures have application as the basis for multistable adaptive systems. The dynamic transition of the bistable structure from its high-energy to low-energy stable states and the lower-frequency return transition are considered by reference to a specific example. The effect of embedded actuation on this behavior is also investigated.

scholarly journals Synthetic dual-function RNA reveals features necessary for target regulation

2021 ◽  
Author(s):  
Jordan J. Aoyama ◽  
Medha Raina ◽  
Gisela Storz
Keyword(s):  
Functional Organization ◽  
Regulatory Protein ◽  
Growth Conditions ◽  
Proper Function ◽  
Dual Function ◽  
Bacterial Cells ◽  
Base Pairing ◽  
Small Protein ◽  
Reading Frame ◽  
Small Proteins

Small base pairing RNAs (sRNAs) and small proteins comprise two classes of regulators that allow bacterial cells to adapt to a wide variety of growth conditions. A limited number of transcripts encoding both of these activities, regulation of mRNA expression by base pairing and synthesis of a small regulatory protein, have been identified. Given that few have been characterized, little is known about the interplay between the two regulatory functions. To investigate the competition between the two activities, we constructed synthetic dual-function RNAs, hereafter referred to as MgtSR or MgtRS, comprised of the Escherichia coli sRNA MgrR and the open reading frame encoding the small protein MgtS. MgrR is a 98 nt base pairing sRNA that negatively regulates eptB encoding phosphoethanolamine transferase. MgtS is a 31 aa small inner membrane protein that is required for the accumulation of MgtA, a magnesium (Mg 2+ ) importer. Expression of the separate genes encoding MgrR and MgtS is normally induced in response to low Mg 2+ by the PhoQP two-component system. By generating various versions of this synthetic dual-function RNA, we probed how the organization of components and the distance between the coding and base pairing sequences contribute to the proper function of both activities of a dual-function RNA. By understanding the features of natural and synthetic dual-function RNAs, future synthetic molecules can be designed to maximize their regulatory impact. IMPORTANCE Dual-function RNAs in bacteria encode a small protein and also base pair with mRNAs to act as small, regulatory RNAs. Given that only a limited number of dual-function RNAs have been characterized, further study of these regulators is needed to increase understanding of their features. This study demonstrates that a functional synthetic dual-regulator can be constructed from separate components and used to study the functional organization of dual-function RNAs, with the goal of exploiting these regulators.

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