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Current Protocols in Molecular Biology Jan 2019We provide protocols for titering and isolating bacterial colonies from single cells by serial dilutions, for streaking agar plates, and for spreading suspensions of...
We provide protocols for titering and isolating bacterial colonies from single cells by serial dilutions, for streaking agar plates, and for spreading suspensions of cells on plates. Support protocols describe replica plating and methods for storing strains as agar stabs and frozen stocks. © 2018 by John Wiley & Sons, Inc.
Topics: Agar; Bacteriological Techniques; Colony Count, Microbial; Culture Media; Escherichia coli; Preservation, Biological
PubMed: 30414382
DOI: 10.1002/cpmb.82 -
Human Fertility (Cambridge, England) Mar 2011This study was designed to establish whether motile spermatozoa are released with pre-ejaculatory fluid and whether this fluid therefore poses a risk for unintended...
This study was designed to establish whether motile spermatozoa are released with pre-ejaculatory fluid and whether this fluid therefore poses a risk for unintended pregnancy. Forty samples of pre-ejaculatory fluid were examined from 27 volunteer men. Samples were obtained by masturbation and by touching the end of the penis with a Petri dish prior to ejaculation. Eleven of the 27 subjects (41%) produced pre-ejaculatory samples that contained spermatozoa and in 10 of these cases (37%), a reasonable proportion of the sperm was motile. The volunteers produced on up to five separate occasions and sperms were found in either all or none of their pre-ejaculatory samples. Hence, condoms should continue to be used from the first moment of genital contact, although it may be that some men, less likely to leak spermatozoa in their pre-ejaculatory fluid, are able to practice coitus interruptus more successfully than others.
Topics: Condoms; Ejaculation; Humans; Male; Penis; Semen; Sperm Motility; Spermatozoa
PubMed: 21155689
DOI: 10.3109/14647273.2010.520798 -
Disaster Medicine and Public Health... Jun 2020
Topics: COVID-19; Coronavirus Infections; Humans; Pandemics; Pneumonia, Viral; Quarantine; Ships
PubMed: 32241332
DOI: 10.1017/dmp.2020.67 -
PLoS Pathogens Jul 2022Mycobacteriophages-bacteriophages infecting Mycobacterium hosts-contribute substantially to our understanding of viral diversity and evolution, provide resources for... (Review)
Review
Mycobacteriophages-bacteriophages infecting Mycobacterium hosts-contribute substantially to our understanding of viral diversity and evolution, provide resources for advancing Mycobacterium genetics, are the basis of high-impact science education programs, and show considerable therapeutic potential. Over 10,000 individual mycobacteriophages have been isolated by high school and undergraduate students using the model organism Mycobacterium smegmatis mc2155 and 2,100 have been completely sequenced, giving a high-resolution view of the phages that infect a single common host strain. The phage genomes are revealed to be highly diverse and architecturally mosaic and are replete with genes of unknown function. Mycobacteriophages have provided many widely used tools for Mycobacterium genetics including integration-proficient vectors and recombineering systems, as well as systems for efficient delivery of reporter genes, transposons, and allelic exchange substrates. The genomic insights and engineering tools have facilitated exploration of phages for treatment of Mycobacterium infections, although their full therapeutic potential has yet to be realized.
Topics: Bacteriophages; Genome, Viral; Humans; Mycobacteriophages; Mycobacterium; Mycobacterium Infections; Mycobacterium smegmatis
PubMed: 35797343
DOI: 10.1371/journal.ppat.1010602 -
Molecular Genetics and Genomics : MGG Feb 2012Optogenetics is a rapidly evolving field of technology that allows optical control of genetically targeted biological systems at high temporal and spatial resolution. By... (Review)
Review
Optogenetics is a rapidly evolving field of technology that allows optical control of genetically targeted biological systems at high temporal and spatial resolution. By heterologous expression of light-sensitive microbial membrane proteins, opsins, cell type-specific depolarization or silencing can be optically induced on a millisecond time scale. What started in a petri dish is applicable today to more complex systems, ranging from the dissection of brain circuitries in vitro to behavioral analyses in freely moving animals. Persistent technical improvement has focused on the identification of new opsins, suitable for optogenetic purposes and genetic engineering of existing ones. Optical stimulation can be combined with various readouts defined by the desired resolution of the experimental setup. Although recent developments in optogenetics have largely focused on neuroscience it has lately been extended to other targets, including stem cell research and regenerative medicine. Further development of optogenetic approaches will not only highly increase our insight into health and disease states but might also pave the way for a future use in therapeutic applications.
Topics: Animals; Gene Expression; Genetic Engineering; Humans; Membrane Potentials; Neurons; Neurosciences; Opsins; Photic Stimulation; Technology
PubMed: 22183142
DOI: 10.1007/s00438-011-0663-7 -
ELife Mar 2015The roundworm Caenorhabditis elegans has risen to the status of a top model organism for biological research in the last fifty years. Among laboratory animals, this tiny... (Review)
Review
The roundworm Caenorhabditis elegans has risen to the status of a top model organism for biological research in the last fifty years. Among laboratory animals, this tiny nematode is one of the simplest and easiest organisms to handle. And its life outside the laboratory is beginning to be unveiled. Like other model organisms, C. elegans has a boom-and-bust lifestyle. It feasts on ephemeral bacterial blooms in decomposing fruits and stems. After resource depletion, its young larvae enter a migratory diapause stage, called the dauer. Organisms known to be associated with C. elegans include migration vectors (such as snails, slugs and isopods) and pathogens (such as microsporidia, fungi, bacteria and viruses). By deepening our understanding of the natural history of C. elegans, we establish a broader context and improved tools for studying its biology.
Topics: Animals; Caenorhabditis; Caenorhabditis elegans; Ecosystem; Female; Humans; Life Cycle Stages; Male; Phylogeny; Population Dynamics
PubMed: 25822066
DOI: 10.7554/eLife.05849 -
Materials (Basel, Switzerland) Dec 2019The classic cell culture involves the use of support in two dimensions, such as a well plate or a Petri dish, that allows the culture of different types of cells.... (Review)
Review
The classic cell culture involves the use of support in two dimensions, such as a well plate or a Petri dish, that allows the culture of different types of cells. However, this technique does not mimic the natural microenvironment where the cells are exposed to. To solve that, three-dimensional bioprinting techniques were implemented, which involves the use of biopolymers and/or synthetic materials and cells. Because of a lack of information between data sources, the objective of this review paper is, to sum up, all the available information on the topic of bioprinting and to help researchers with the problematics with 3D bioprinters, such as the 3D-Bioplotter™. The 3D-Bioplotter™ has been used in the pre-clinical field since 2000 and could allow the printing of more than one material at the same time, and therefore to increase the complexity of the 3D structure manufactured. It is also very precise with maximum flexibility and a user-friendly and stable software that allows the optimization of the bioprinting process on the technological point of view. Different applications have resulted from the research on this field, mainly focused on regenerative medicine, but the lack of information and/or the possible misunderstandings between papers makes the reproducibility of the tests difficult. Nowadays, the 3D Bioprinting is evolving into another technology called 4D Bioprinting, which promises to be the next step in the bioprinting field and might promote great applications in the future.
PubMed: 31810326
DOI: 10.3390/ma12234005 -
Journal of Visualized Experiments : JoVE Feb 2021To select food with nutritional value while avoiding the consumption of harmful agents, animals need a sophisticated and robust taste system to evaluate their food...
To select food with nutritional value while avoiding the consumption of harmful agents, animals need a sophisticated and robust taste system to evaluate their food environment. The fruit fly, Drosophila melanogaster, is a genetically tractable model organism that is widely used to decipher the molecular, cellular, and neural underpinnings of food preference. To analyze fly food preference, a robust feeding method is needed. Described here is a two-choice feeding assay, which is rigorous, cost-saving, and fast. The assay is Petri-dish-based and involves the addition of two different foods supplemented with blue or red dye to the two halves of the dish. Then, ~70 prestarved, 2-4-day-old flies are placed in the dish and allowed to choose between blue and red foods in the dark for about 90 min. Examination of the abdomen of each fly is followed by the calculation of the preference index. In contrast to multiwell plates, each Petri dish takes only ~20 s to fill and saves time and effort. This feeding assay can be employed to quickly determine whether flies like or dislike a particular food.
Topics: Animals; Biological Assay; Coloring Agents; Drosophila melanogaster; Feeding Behavior; Food Preferences; Indicators and Reagents; Starvation
PubMed: 33645577
DOI: 10.3791/62051 -
Biomedical Microdevices May 2022Three-dimensional cell agglomerates are broadly useful in tissue engineering and drug testing. We report a well-free method to form large (1.4-mm) multicellular clusters...
Three-dimensional cell agglomerates are broadly useful in tissue engineering and drug testing. We report a well-free method to form large (1.4-mm) multicellular clusters using 100-MHz surface acoustic waves (SAW) without direct contact with the media or cells. A fluid couplant is used to transform the SAW into acoustic streaming in the cell-laden media held in a petri dish. The couplant transmits longitudinal sound waves, forming a Lamb wave in the petri dish that, in turn, produces longitudinal sound in the media. Due to recirculation, human embryonic kidney (HEK293) cells in the dish are carried to the center of the coupling location, forming a cluster in less than 10 min. A few minutes later, these clusters may then be translated and merged to form large agglomerations, and even repeatedly folded to produce a roughly spherical shape of over 1.4 mm in diameter for incubation-without damaging the existing intercellular bonds. Calcium ion signaling through these clusters and confocal images of multiprotein junctional complexes suggest a continuous tissue construct: intercellular communication. They may be formed at will, and the method is feasibly useful for formation of numerous agglomerates in a single petri dish.
Topics: Acoustics; Animals; Cell Communication; Culture Media; HEK293 Cells; Humans; Sheep; Sound
PubMed: 35596837
DOI: 10.1007/s10544-022-00617-z