2,857 research outputs found
Eukaryotic Transcription: What Does It Mean for a Gene to Be ‘on’?
Until recently, transcription could only be observed by measuring mRNA production of cell populations, thus obscuring the kinetics at the level of individual transcription events. A new study now shows that eukaryotic transcription, visualised in individual living cells, occurs in bursts — much as it does in prokaryotes
Protein synthesis molecule by molecule
Since the earliest days of molecular biology it has been known that even a seemingly uniform culture of bacteria is made up of cells very different from each other in terms of their levels of a given protein. This individuality has now finally been quantified at single-molecule resolution, as reported in two recent papers
Site-specific chromosomal integration of large synthetic constructs
We have developed an effective, easy-to-use two-step system for the site-directed insertion of large genetic constructs into arbitrary positions in the Escherichia coli chromosome. The system uses λ-Red mediated recombineering accompanied by the introduction of double-strand DNA breaks in the chromosome and a donor plasmid bearing the desired insertion fragment. Our method, in contrast to existing recombineering or phage-derived insertion methods, allows for the insertion of very large fragments into any desired location and in any orientation. We demonstrate this method by inserting a 7-kb fragment consisting of a venus-tagged lac repressor gene along with a target lacZ reporter into six unique sites distributed symmetrically about the chromosome. We also demonstrate the universality and repeatability of the method by separately inserting the lac repressor gene and the lacZ target into the chromosome at separate locations around the chromosome via repeated application of the protocol
SB 2025, Fishing in Certain Waters – House Committee on Ocean and Marine Resources Public Hearing – March 13, 1986
High-throughput analysis of spatio-temporal dynamics in Dictyostelium
A time-lapse based approach is presented that allows a rapid examination of the spatio-temporal dynamics of Dictyostelium cell populations, enabling users to search and retrieve movies on a gene-by-gene and phenotype-by-phenotype basis
A Method of Hospital Infection Surveillance Incorporating the Use of the Computer
The records of all patients in the hospital on a particular date were studied for hospital-acquired infections. Results were compared with a continuing surveillance based on discharge reporting. Collection of data was programmed for analysis by using the hospital computer. Thirteen per cent of the patients manifested an infection after admission, but before or on the survey day. Results elsewhere are similar. Areas of the hospital with a relatively higher incidence of infection did not have clusters of particular pathogens
Spatial patterns in the fruiting bodies of the cellular slime mold Polysphondylium pallidum
During morphogenesis in the slime mold Polysphondylium pallidum cell masses are periodically pinched off from the base of the developing sorogen. These masses round up and differentiate into secondary sorogens, which become radially ordered arrays of secondary fruiting bodies called whorls. Here we describe the morphogenesis of P. pallidum and characterize the spacing of whorls along the central stalk of the fruiting body and the spacing of soro-carps within whorls. We find both are highly regular. We propose that the linear spacing of whorls can be accounted for satisfactorily by a model that views the periodic release of cell masses from the base of the developing sorogen as the consequence of an imbalance between forces that orient amoebae toward the tip of the culminating sorogen, and cohesive forces between randomly moving cells in the basal region of the sorogen, which act as a retarding force. The orderly arrangement of fruiting bodies within whorls can be explained most easily by models that employ short-range activation and lateral inhibition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72498/1/j.1432-0436.1988.tb00200.x.pd
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How to connect time-lapse recorded trajectories of motile microorganisms with dynamical models in continuous time
Novel SCN9A mutations underlying extreme pain phenotypes: unexpected electrophysiological and clinical phenotype correlations.
The importance of NaV1.7 (encoded by SCN9A) in the regulation of pain sensing is exemplified by the heterogeneity of clinical phenotypes associated with its mutation. Gain-of-function mutations are typically pain-causing and have been associated with inherited erythromelalgia (IEM) and paroxysmal extreme pain disorder (PEPD). IEM is usually caused by enhanced NaV1.7 channel activation, whereas mutations that alter steady-state fast inactivation often lead to PEPD. In contrast, nonfunctional mutations in SCN9A are known to underlie congenital insensitivity to pain (CIP). Although well documented, the correlation between SCN9A genotypes and clinical phenotypes is still unclear. Here we report three families with novel SCN9A mutations. In a multiaffected dominant family with IEM, we found the heterozygous change L245 V. Electrophysiological characterization showed that this mutation did not affect channel activation but instead resulted in incomplete fast inactivation and a small hyperpolarizing shift in steady-state slow inactivation, characteristics more commonly associated with PEPD. In two compound heterozygous CIP patients, we found mutations that still retained functionality of the channels, with two C-terminal mutations (W1775R and L1831X) exhibiting a depolarizing shift in channel activation. Two mutations (A1236E and L1831X) resulted in a hyperpolarizing shift in steady-state fast inactivation. To our knowledge, these are the first descriptions of mutations with some retained channel function causing CIP. This study emphasizes the complex genotype-phenotype correlations that exist for SCN9A and highlights the C-terminal cytoplasmic region of NaV1.7 as a critical region for channel function, potentially facilitating analgesic drug development studies.J.J.C. and A.M.H. were supported by an MRC Research Career Development fellowship. F.M.G., F.R., and E.C.E.
were supported by Wellcome Trust Senior Fellowships WT088357/Z/09/Z and WT084210/Z/07/Z and MRC Grant
MC_UU_12012/3. C.G.W. was supported by the Cambridge Biomedical Research Campus.This is the final published version. It first appeared at http://www.jneurosci.org/content/35/20/7674.short
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