The authors have nothing to disclose.

maintaining wolbachia in cell-free medium

In this video protocol, procedures are demonstrated to (1) purify Wolbachia symbionts out of cultured mosquito cells, (2) use a fluorescent assay to ascertain the viability of the purified Wolbachia and (3) maintain the now extracellular Wolbachia in cell-free medium.  Purified Wolbachia remain alive in the extracellular phase but do not replicate until re-inoculated into eukaryotic cells.  Extracellular Wolbachia purified in this manner will remain viable for at least a week at room temperature, and possibly longer.  Purified Wolbachia are suitable for micro-injection, DNA extraction and other applications. 


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Maintaining Wolbachia in Cell-free Medium

This video describes a method for purifying Wolbachia pipientis from an Anopheles gambiae cell line and then culturing the endosymbiont in cell-free medium. An assay for viability of the bacterium is demonstrated.

In this video protocol, procedures are demonstrated to (1) purify Wolbachia symbionts out of cultured mosquito cells, (2) use a fluorescent assay to ...

maintaining-wolbachia-in-cell-free-medium

Research

JoVE Journal

Biology

10.3K Views.  Johns Hopkins University. This video describes a method for purifying Wolbachia pipientis from an Anopheles gambiae cell line and then culturing the endosymbiont in cell-free medium. An assay for viability of the bacterium is demonstrated.

Video: Maintaining Wolbachia in Cell-free Medium

Wolbachia Bacterial Infection in Drosophila

My name is Voia Friedman. I am associate researcher at Princeton University. And today I'm going to tell you about a few protocols that I developed to trans infect, to I initially to isolate, to go back from the heli of infected flies, and later on help to inject the heli feed to unaffected flights.So basically, this is a very simple protocol to isolate him oly for basics. And you will use this device from, from mepo that contains a filter that goes on top of an E.So you basically needs to put you, we start from around a hundred flies. You anize the flies, you put them into the filter device, you can just use a funnel and that will add our other fit very easily on this device and wash it with 70%ethanol.You just take the, take the future away, you can throw away the ethanol, and then after three times your last wash you do with molecule water because you don't want have the bacteria from the, with traces of ethanol. Well, and then you just go to a new weapon door and, and then you spin down on a micro, real micro for two minutes And later on how you can inject that. He only feed do unaffected flies.So basically take a double stick tape and usually these double stick tapes have two side, one side is a sticker than the other. So leave the sticker side up because that's the side that you're gonna glue that flies on top of it. And basically you'll, the gas apparatus, if you have this light on top of it, you'll be no gas flow and the flies you wake up if they're on top of the slide.So you can just direct the flow, making a little hood, a little chamber using tape. Then you direct the gas over the flies. So then you put your, this light here with the tape and you, you have your flies.Stick the flies on the top of the tape, all of them the same orientation, and put their head towards the direction that you'll be bringing the needle from. Because then you can just over the, the wing, you make sure since they fly, you don't want to fly. If they woke up during the procedure, don't want them to go away.So make sure that you take a little tip and pressure against the, the, the wings of the fly on the tail. And it's okay if they wings get damaged. And when you get rid, when you take the flies up the injection, most likely they'll lose their wings anyway, so they'll survive.That can, that can be useful because you're not gonna lose the flies that, so he puts a mineral oil on the micrometer for the back of the needle, then the needle injection polar, and then the, you can just adjust the pressure to bring the material up to the tip of the needle. I, I did to inject Somewhere between 10 to 15 nanoliters, but as, as long, as long as I'm consistents. Okay, so one important detail there is a cushion of this experiment is that the, the fly, once the apply is being injected when you saw the needle needs to come as far as you can through the upper part of the abdomen.Because here, basically when the needle penetrates, you have a, a, a, a, a bigger space to go up and down. And basically if it's close, closer to the cuticle, it's less likely they're gonna penetrate vital organs in the flight. You, it is very likely unlikely that you're gonna punch a hole in your gut, for instance, if that is gonna kill the flight that you are performing the surgery.My name is Voia Friedman. I am associate researcher at Princeton University in the lab of Eric Hels. And today I would like to tell you about this protocol that you just saw, the demonstration.So this protocol was done because we wanted to prove that UBA is capable of crossing tissues. So UBA is one of the most successful intracellular paras on the face of the earth. Infects from 20 to 70%of insects and many particles.And also is, is very important in terms of human diseases because also infect nematodes that transmit diseases like river blindness or s and ssis. And so, and CCA is our obligatory endo in, in these worms. And there's a great, a very big interest in using CCA also as means to control parasitic diseases transmitter by mosquito and Danny and this and by mosquito such as malaria and dengue.So this, this, this protocol basically was developed to show that once CCA inside the abdominal cavity of a fly, they can cross tissues and reach the germ. So basically what you can see here is the oph of the drosophila ovary and go back once present in the he leaf it, it can cross a pink peronial. She that is around the ovary.And then they cross a muscle layer. And actually one of the first places that they, they go inside the ovary is the somatic stem cell image. And then they can reach the germline.And this bacteria is transmitted the same way that mitochondria is transmitted is through, is through the mother transmitted, through the mother cyop plants present in the egg. So of course they needs to be present into the germline. So that's why this protocol is developed.And this protocol is, can be very useful to basically traditionally the way that people would try to trans infect wbaa basically take wbaa and introduce a new insect species. It would be through doing micro injections into the, into the embryo. But those are much more complicated.And basically here we are just taking advantage of the o biology since they are capable to cross tissues and moving into the stem cell tissues from, they can pass to the, through to the germline. So that's make easier taking UBA from certain, from, from certain species of insects that are infected and they can be transmitted to uninfected species. Prob I think it's the injection itself.Basically you need to be careful to mobilize the fly as well as you can. We are using double sided stick tape and you need to penetrate the needle basically as close to the, as parallel to the fly as possible so you don't go to deep. And it's less likely that we're gonna kill the fly after they're performing the surgery.

Population Replacement Strategies for Controlling Vector Populations and the Use of Wolbachia pipientis for Genetic Drive

In this video, Jason Rasgon discusses population replacement strategies to control vector-borne diseases such as malaria and dengue. "Population replacement" is the replacement of wild vector populations (that are competent to transmit pathogens) with those that are not competent to transmit pathogens. There are several theoretical strategies to accomplish this. One is to exploit the maternally-inherited symbiotic bacteria Wolbachia pipientis. Wolbachia is a widespread reproductive parasite that spreads in a selfish manner at the extent of its host's fitness. Jason Rasgon discusses, in detail, the basic biology of this bacterial symbiont and various ways to use it for control of vector-borne diseases.

In this interview, Jason Rasgon explains the concept of genetic drive and the characteristics of an effective gene drive system. The use of the endosymbiotic bacterium, Wolbachia pipientis, as a means to spread genes through mosquito populations, is hypothesized.

In this video, Jason Rasgon discusses population replacement strategies to control vector-borne diseases such as malaria and dengue. "Population ...

A Simple Method for Imaging Arabidopsis Leaves Using Perfluorodecalin as an Infiltrative Imaging Medium

The problem of acquiring high-resolution images deep into biological samples is widely acknowledged1. In air-filled tissue such as the spongy mesophyll of plant leaves or vertebrate lungs further difficulties arise from multiple transitions in refractive index between cellular components, between cells and airspaces and between the biological tissue and the rest of the optical system. Moreover, refractive index mismatches lead to attenuation of fluorophore excitation and signal emission in fluorescence microscopy. We describe here the application of the perfluorocarbon, perfluorodecalin (PFD), as an infiltrative imaging medium which optically improves laser scanning confocal microscopy (LSCM) sample imaging at depth, without resorting to damaging increases in laser power and has minimal physiological impact2. We describe the protocol for use of PFD with Arabidopsis thaliana leaf tissue, which is optically complex as a result of its structure (Figure 1). PFD has a number of attributes that make it suitable for this use3. The refractive index of PFD (1.313) is comparable with that of water (1.333) and is closer to that of cytosol (approx. 1.4) than air (1.000). In addition, PFD is readily available, non-fluorescent and is non-toxic. The low surface tension of PFD (19 dynes cm-1) is lower than that of water (72 dynes cm-1) and also below the limit (25 - 30 dyne cm-1) for stomatal penetration4, which allows it to flood the spongy mesophyll airspaces without the application of a potentially destructive vacuum or surfactant. Finally and crucially, PFD has a great capacity for dissolving CO2 and O2, which allows gas exchange to be maintained in the flooded tissue, thus minimizing the physiological impact on the sample. These properties have been used in various applications which include partial liquid breathing and lung inflation5,6, surgery7, artificial blood8, oxygenation of growth media9, and studies of ice crystal formation in plants10. Currently, it is common to mount tissue in water or aqueous buffer for live confocal imaging. We consider that the use of PFD as a mounting medium represents an improvement on existing practice and allows the simple preparation of live whole leaf samples for imaging.

A Simple Method for Imaging Arabidopsis Leaves Using Perfluorodecalin as an Infiltrative Imaging Medium

We describe the use of perfluorodecalin as an infiltrative mounting medium. This is a simple method for improving depth of imaging in Arabidopsis thaliana leaf tissue with minimal physiological impact.

The problem of acquiring high-resolution images deep into biological samples is widely acknowledged1. In air-filled tissue such as the spongy mesophyll of ...

Assaying Proteasomal Degradation in a Cell-free System in Plants

The ubiquitin-proteasome pathway for protein degradation has emerged as one of the most important mechanisms for regulation of a wide spectrum of cellular functions in virtually all eukaryotic organisms. Specifically, in plants, the ubiquitin/26S proteasome system (UPS) regulates protein degradation and contributes significantly to development of a wide range of processes, including immune response, development and programmed cell death. Moreover, increasing evidence suggests that numerous plant pathogens, such as Agrobacterium, exploit the host UPS for efficient infection, emphasizing the importance of UPS in plant-pathogen interactions.
The substrate specificity of UPS is achieved by the E3 ubiquitin ligase that acts in concert with the E1 and E2 ligases to recognize and mark specific protein molecules destined for degradation by attaching to them chains of ubiquitin molecules. One class of the E3 ligases is the SCF (Skp1/Cullin/F-box protein) complex, which specifically recognizes the UPS substrates and targets them for ubiquitination via its F-box protein component. To investigate a potential role of UPS in a biological process of interest, it is important to devise a simple and reliable assay for UPS-mediated protein degradation. Here, we describe one such assay using a plant cell-free system. This assay can be adapted for studies of the roles of regulated protein degradation in diverse cellular processes, with a special focus on the F-box protein-substrate interactions.

Targeted protein degradation represents a major regulatory mechanism for cell function. It occurs via a conserved ubiquitin-proteasome pathway, which attaches polyubiquitin chains to the target protein that then serve as molecular &#8220;tags&#8221; for the 26S proteasome. Here, we describe a simple and reliable cell-free assay for proteasomal degradation of proteins.

The ubiquitin-proteasome pathway for protein degradation has emerged as one of the most important mechanisms for regulation of a wide spectrum of cellular ...

Analysis of RNA Processing Reactions Using Cell Free Systems: 3' End Cleavage of Pre-mRNA Substrates in vitro

The 3&#8217; end of mammalian mRNAs is not formed by abrupt termination of transcription by RNA polymerase II (RNPII). Instead, RNPII synthesizes precursor mRNA beyond the end of mature RNAs, and an active process of endonuclease activity is required at a specific site. Cleavage of the precursor RNA normally occurs 10-30 nt downstream from the consensus polyA site (AAUAAA) after the CA dinucleotides. Proteins from the cleavage complex, a multifactorial protein complex of approximately 800 kDa, accomplish this specific nuclease activity. Specific RNA sequences upstream and downstream of the polyA site control the recruitment of the cleavage complex. Immediately after cleavage, pre-mRNAs are polyadenylated by the polyA polymerase (PAP) to produce mature stable RNA messages.
Processing of the 3&#8217; end of an RNA transcript may be studied using cellular nuclear extracts with specific radiolabeled RNA substrates. In sum, a long 32P-labeled uncleaved precursor RNA is incubated with nuclear extracts in vitro, and cleavage is assessed by gel electrophoresis and autoradiography. When proper cleavage occurs, a shorter 5&#8217; cleaved product is detected and quantified. Here, we describe the cleavage assay in detail using, as an example, the 3&#8217; end processing of HIV-1 mRNAs.

Analysis of RNA Processing Reactions Using Cell Free Systems: 3' End Cleavage of Pre-mRNA Substrates in vitro

RNA polymerase II synthesizes a precursor RNA that extends beyond the 3' end of the mature mRNA. The end of the mature RNA is generated cotranscriptionally, at a site dictated by RNA sequences, via the endonuclease activity of the cleavage complex. Here, we detail the method to study cleavage reactions in vitro.

The 3&#8217; end of mammalian mRNAs is not formed by abrupt termination of transcription by RNA polymerase II (RNPII). Instead, RNPII synthesizes ...

Bone Conditioned Medium: Preparation and Bioassay

Autologous bone grafts are widely used in oral and maxillofacial surgery, orthopedics, and traumatology. Autologous bone grafts not only replace missing bone, they also support the complex process of bone regeneration. This favorable behavior of autografts is attributed to the three characteristics: osteoconductivity, osteogenicity, and osteoinductivity. However, there is another aspect: Bone grafts release a myriad of molecules, including growth factors, which can target mesenchymal cells involved in bone regeneration. The paracrine properties of bone grafts can be studied in vitro by the use of bone-conditioned medium (BCM). Here we present a protocol on how to prepare bone-conditioned medium from native pig cortical bone, and bone that underwent thermal processing or demineralization. Cells can be directly exposed to BCM or seeded onto biomaterials, such as collagen membranes, previously soaked with BCM. We give examples for in vitro bioassays with mesenchymal cells on the expression of TGF-&#946; regulated genes. The presented protocols should encourage to further reveal the paracrine effects of bone grafts during bone regeneration and open a path for translational research in the broad field of reconstructive surgery.

We describe here how to prepare bone-conditioned medium (BCM) and test its activity in vitro.

Autologous bone grafts are widely used in oral and maxillofacial surgery, orthopedics, and traumatology. Autologous bone grafts not only replace missing ...

HeLa Based Cell Free Expression Systems for Expression of Plasmodium Rhoptry Proteins

Malaria causes significant global morbidity and mortality. No routine vaccine is currently available. One of the major reasons for lack of a vaccine is the challenge of identifying suitable vaccine candidates. Malarial proteins expressed using prokaryotic and eukaryotic cell based expression systems are poorly glycosylated, generally insoluble and undergo improper folding leading to reduced immunogenicity. The wheat germ, rabbit reticulocyte lysate and Escherichia coli lysate cell free expression systems are currently used for expression of malarial proteins. However, the length of expression time and improper glycosylation of proteins still remains a challenge. We demonstrate expression of Plasmodium proteins in vitro using HeLa based cell free expression systems, termed &#8220;in vitro human cell free expression systems&#8221;. The 2 HeLa based cell free expression systems transcribe mRNA in 75 min and 3 &#181;l of transcribed mRNA is sufficient to translate proteins in 90 min. The 1-step expression system is a transcription and translation coupled expression system; the transcription and co-translation occurs in 3 hr. The process can also be extended for 6 hr by providing additional energy. In the 2-step expression system, mRNA is first transcribed and then added to the translation mix for protein expression. We describe how to express malaria proteins; a hydrophobic PF3D7_0114100 Maurer&#8217;s Cleft &#8211; 2 transmembrane (PfMC-2TM) protein, a hydrophilic PF3D7_0925900 protein and an armadillo repeats containing protein PF3D7_1361800, using the HeLa based cell free expression system. The proteins are expressed in micro volumes employing 2-step and 1-step expression strategies. An affinity purification method to purify 25 &#181;l of proteins expressed using the in vitro human cell free expression system is also described. Protein yield is determined by Bradford&#8217;s assay and the expressed and purified proteins can be confirmed by western blotting analysis. Expressed recombinant proteins can be used for immunizations, immunoassays and protein sequencing.

HeLa Based Cell Free Expression Systems for Expression of Plasmodium Rhoptry Proteins

Expression of malarial proteins in cell based systems remains challenging. We demonstrate two step and one step IVT (in vitro translation) cell free expression systems for expressing malarial recombinant rhoptry proteins from HeLa cells. We use a Ni-resin affinity based purification system to purify the rhoptry proteins.

Malaria causes significant global morbidity and mortality. No routine vaccine is currently available. One of the major reasons for lack of a vaccine is ...

A Cell Free Assay to Study Chromatin Decondensation at the End of Mitosis

During the vertebrate cell cycle chromatin undergoes extensive structural and functional changes. Upon mitotic entry, it massively condenses into rod shaped chromosomes which are moved individually by the mitotic spindle apparatus. Mitotic chromatin condensation yields chromosomes compacted fifty-fold denser as in interphase. During exit from mitosis, chromosomes have to re-establish their functional interphase state, which is enclosed by a nuclear envelope and is competent for replication and transcription. The decondensation process is morphologically well described, but in molecular terms poorly understood: We lack knowledge about the underlying molecular events and to a large extent the factors involved as well as their regulation. We describe here a cell-free system that faithfully recapitulates chromatin decondensation in vitro, based on mitotic chromatin clusters purified from synchronized HeLa cells and X. laevis egg extract. Our cell-free system provides an important tool for further molecular characterization of chromatin decondensation and its co-ordination with processes simultaneously occurring during mitotic exit such as nuclear envelope and pore complex re-assembly.

The molecular mechanisms of the decondensation of highly compacted mitotic chromatin are ill-defined. We present a cell-free assay based on mitotic chromatin clusters isolated from HeLa cells and Xenopus laevis egg extract that faithfully reconstitutes the decondensation process in vitro.

During the vertebrate cell cycle chromatin undergoes extensive structural and functional changes. Upon mitotic entry, it massively condenses into rod ...

A Cell-Free Assay Using Xenopus laevis Embryo Extracts to Study Mechanisms of Nuclear Size Regulation

A fundamental question in cell biology is how cell and organelle sizes are regulated. It has long been recognized that the size of the nucleus generally scales with the size of the cell, notably during embryogenesis when dramatic reductions in both cell and nuclear sizes occur. Mechanisms of nuclear size regulation are largely unknown and may be relevant to cancer where altered nuclear size is a key diagnostic and prognostic parameter. In vivo approaches to identifying nuclear size regulators are complicated by the essential and complex nature of nuclear function. The in vitro approach described here to study nuclear size control takes advantage of the normal reductions in nuclear size that occur during Xenopus laevis development. First, nuclei are assembled in X. laevis egg extract. Then, these nuclei are isolated and resuspended in cytoplasm from late stage embryos. After a 30 - 90 min incubation period, nuclear surface area decreases by 20 - 60%, providing a useful assay to identify cytoplasmic components present in late stage embryos that contribute to developmental nuclear size scaling. A major advantage of this approach is the relative facility with which the egg and embryo extracts can be biochemically manipulated, allowing for the identification of novel proteins and activities that regulate nuclear size. As with any in vitro approach, validation of results in an in vivo system is important, and microinjection of X. laevis embryos is particularly appropriate for these studies.

A Cell-Free Assay Using Xenopus laevis Embryo Extracts to Study Mechanisms of Nuclear Size Regulation

Mechanisms of cellular and intra-cellular scaling remain elusive. The use of Xenopus embryo extracts has become increasingly common to elucidate mechanisms of organelle size regulation. This method describes embryo extract preparation and a novel nuclear scaling assay through which mechanisms of nuclear size regulation can be identified.

A fundamental question in cell biology is how cell and organelle sizes are regulated. It has long been recognized that the size of the nucleus generally ...

Visualization and Quantification of the Cell-free Layer in Arterioles of the Rat Cremaster Muscle

The cell-free layer is defined as the parietal plasma layer in the microvessel flow, which is devoid of red blood cells. The measurement of the in vivo cell-free layer width and its spatiotemporal variations can provide a comprehensive understanding of hemodynamics in microcirculation. In this study, we used an intravital microscopic system coupled with a high-speed video camera to quantify the cell-free layer widths in arterioles in vivo. The cremaster muscle of Sprague-Dawley rats was surgically exteriorized to visualize the blood flow. A custom-built imaging script was also developed to automate the image processing and analysis of the cell-free layer width. This approach enables the quantification of spatiotemporal variations more consistently than previous manual measurements. The accuracy of the measurement, however, partly depends on the use of a blue filter and the selection of an appropriate thresholding algorithm. Specifically, we evaluated the contrast and quality of images acquired with and without the use of a blue filter. In addition, we compared five different image histogram-based thresholding algorithms (Otsu, minimum, intermode, iterative selection, and fuzzy entropic thresholding) and illustrated the differences in their determination of the cell-free layer width.

This study demonstrates the surgical preparation of the rat cremaster muscle for the visualization of the in vivo cell-free layer. Considerable factors affecting the accuracy of the cell-free layer width measurement are discussed in this study.

The cell-free layer is defined as the parietal plasma layer in the microvessel flow, which is devoid of red blood cells. The measurement of the in vivo ...