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  • TEM and STEM
    Transmission Electron Microscopy  Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. Compare to the light microscope, TEMs use electrons as "light source" and their much lower wavelength makes it possible to get a resolution a thousand times better than with a light microscope. The possibility for high magnifications has made the TEM a valuable tool in both medical, biological and materials research. Fig. 1 Structure of TEM Scanning Transmission Electron Microscopy Scanning transmission electron microscopy (STEM) combines the principles of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and can be performed on either type of instrument, As with a transmission electron microscope (TEM), images are formed by electrons passing through a sufficiently thin specimen. However, unlike TEM, in STEM the electron beam is focused to a fine spot which is then scanned over the sample in a raster.  This kind of microscopy are usually used to characterize the nanoscale, and atomic scale struct...
  • Microinjection Services
    Microinjection is a technique of delivering foreign DNA into a living cell (a cell, egg, oocyte, embryos of animals) through a glass micropipette. One end of a glass micropipette is heated until the glass becomes somewhat liquified. It is quickly stretched which forms a very fine tip at the heated end. The tip of the pipette attains to about 0.5 mm diameter which resembles an injection needle. The process of delivering foreign DNA is done under a powerful microscope. Cells to be micro-injected are placed in a container. A holding pipette is placed in the field of view of the microscope. The holding pipette holds a target cell at the tip when gently sucked. The tip of the micropipette is injected through the membrane of the cell. Contents of the needle are delivered into the cytoplasm and the empty needle is taken out.
  • Frozen Section Procedure (Cryosection)
    The frozen section procedure is a pathological laboratory procedure to perform rapid microscopic analysis of a specimen. It is used most often in oncological surgery. The quality of the slides produced by frozen section is lower than formalin fixed paraffin embedded tissue processing. While diagnosis can be rendered in many cases, fixed tissue processing is preferred in many conditions for more accurate diagnosis. Frozen sectioning is the method of choice when paraffin processing may interfere with any downstream techniques. During the frozen section procedure, the surgeon removes a portion of the tissue mass. This biopsy is then given to a pathologist. The pathologist freezes the tissue in a cryostat machine, cuts it with a microtome, and then stains it with various dyes so that it can be examined under the microscope. The procedures are as follows:
  • Paraffin Embedded Tissue Processing
    Biological samples often need to be solidified to allow fine sectioning. Thin slices improve the access of dyes, probes, and antibodies and reduce the overlay of different cells layers in the z direction. For light microscopy, paraffin wax is the most frequently used hard matrix for cutting. When sectioned, the paraffin tissue slides can be used for a variety of purposes such as special stains, immunohistochemistry, and in situ hybridization to study morphology, protein expression, DNA aberrations and RNA expression. The procedures to make Paraffin slides are quite simple: Since paraffin is immiscible with water, the main constituent of tissue, samples need to be dehydrated by progressively more concentrated ethanol baths. This is followed by a clearing agent, usually xylene, to remove the ethanol. Finally, molten paraffin wax infiltrates the sample and replaces the xylene.
  • Transgenic Plants Construction
    Transgenic plants are plants that have been genetically engineered, and are identified as a class of genetically modified organism (GMO). The construction of transgenic plants is a breeding approach that uses recombinant DNA techniques to create plants with new characteristics. The transgenic plants have many advantages compare to traditional plants: it not only Improved the nutritional quality of the plants, but also increase the plant resistance of insects, diseases, herbicides, and salt. There are five steps to produce transgenic plants: 1. Design genes for insertion. 2. Transforming Plants: “Gene Gun” method or Agrobacterium method. 3. Selection of successfully transformed tissues.  4. Regeneration of whole plants. 5. Plant Breeding and Testing.
  • Microorganisms Gene Modification Services
    With the development of recombinant deoxyribonucleic acid (DNA) technology, the metabolic potentials of microorganisms are being explored and harnessed in a variety of new ways. Today, genetically modified microorganisms (GMMs) have found applications in human health, bioremediation, and industries. A number of molecular tools are needed to manipulate microorganisms for the expression of desired traits, include: (1) gene transfer methods to deliver the selected genes into desired hosts; (2) cloning vectors; (3) promoters to control the expression of the desired genes; and (4) selectable marker genes to identify recombinant microorganisms.
  • CRISPR-CAS Technology
    The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) system is a prokaryotic immune system that confers resistance to foreign genetic elements such as those present within plasmids and phages that provides a form of acquired immunity. RNA harboring the spacer sequence helps Cas (CRISPR-associated) proteins recognize and cut exogenous DNA. These sequences play a key role in a bacterial defence system, and form the basis of a technology known as CRISPR/Cas9 that effectively and specifically changes genes within organisms. CRISPR-Cas9 is a unique technology that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence. It is currently the simplest, most versatile and precise method of genetic manipulation. The CRISPR-Cas9 system consists of two key molecules that introduce a mutation into the DNA: Cas9 and gRNA. Cas9 acts as a pair of ‘molecular scissors’ that can cut the two strands of DNA at a specific location in the genome so that bits of DNA can then be added or removed. While the guide RNA (gRNA) i...
  • TALEN Technology
    Transcription activator-like effector nucleases (TALEN) are restriction enzymes that can be engineered to cut specific sequences of DNA. Transcription activator-like effectors (TALEs) can be quickly engineered to bind practically any desired DNA sequence. By combining such an engineered TALE with a DNA cleavage domain (which cuts DNA strands), one can engineer restriction enzymes that will specifically cut any desired DNA sequence. When these restriction enzymes are introduced into cells, they can be used for gene editing or for genome editing in situ, a technique known as genome editing with engineered nucleases. The simple relationship between amino acid sequence and DNA recognition of the TALE binding domain allows for the efficient engineering of proteins. Once the TALEN constructs have been assembled, they are inserted into plasmids; the target cells are then transfected with the plasmids, and the gene products are expressed and enter the nucleus to access the genome. Alternatively, TALEN constructs can be delivered to the cells as mRNAs, which removes the possibility of genomic integration of the TALEN-expressing protein.  Procedure...
  • New Generation Embryonic Stem Cells Gene Targeting
    Gene targeting with homologous recombination in embryonic stem cells created a revolution in the analysis of the function of genes in research.  The development of gene targeting technology, the exchange of an endogenous allele of a target gene for a mutated copy via homologous recombination, and the application of this technique to murine embryonic stem cells has made it possible to alter the germ-line of mice in a predetermined way. It’s becoming common to engineer specific gene mutations in the mouse germline by gene targeting in embryonic stem (ES) cells. This is accomplished by using a targeting vector designed to replace the corresponding endogenous gene by homologous recombination. Since it is much more common for the targeting vector to insert into a random chromosomal site than a homologous one, it’s necessary to screen colonies by Southern hybridization or polymerase chain reaction (PCR) to identify rare targeted clones.
  • Tetracycline Induced Gene knockout/knockin
    Tetracycline (TET) technology allows precise, reversible, and efficient spatiotemporal control of gene expression. This “on demand” gene induction mimics disease onset and disease progression. When coupled with Cre recombinase, TET technology allows one to selectively shut down target gene expression.   There are two most commonly used inducible expression systems of research of eukaryote cell biology: Tet-Off and Tet-On. The Tet-Off system makes use of the tetracycline transactivator (tTA) protein, which is created by fusing TetR (tetracycline repressor), with the activation domain of VP16. The resulting tTA protein is able to bind to DNA at specific TetO operator sequences. In most Tet-off systems, several repeats of such TetO sequences are placed upstream of a minimal promoter such as the CMV promoter. In a Tet-Off system, expression of TRE-controlled genes can be repressed by tetracycline and its derivatives. They bind tTA and render it incapable of binding to TRE sequences, thereby preventing transactivation of TRE-controlled genes. A Tet-On system works similarly, but in the opposite fashion. In a Tet-Off system, tTA is binding the operat...
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