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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. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device. Transmission electron microscopes are capable of imaging at a significantly higher resolution than light microscopes, owing to the smaller de Broglie wavelength of electrons. This enables the instrument to capture fine detail—even as small as a single column of atoms, which is thousands of times smaller than a resolvable object seen in a light microscope. Transmission electron microscopy is a major analytical method in the physical, chemical and biological sciences. TEM instruments boast an enormous array of operating modes including conventional imag...

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Microinjection Services

Introduction (What is Microinjection?) 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. Microinjection Services Microinjection (MIJ) services consist of the instruments, facilities, and technical expertise required for microinjection, which is a necessary step in the creation of genetically modified mouse models. Carry out daily activities such as mouse colonies ma...

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Frozen Section Procedure (Cryosection)

What is a Frozen Section? A frozen section is the tissue portion that uses a cryometer to cool quickly. This is an important feature of hospitals to assist in diagnosing lesions and the degree of lesions during surgery. A refrigerant is an instrument used to freeze samples of human tissue and cut them into microscopic parts. It is used to help diagnose lesions immediately and to help medical professionals plan for the management of the patients involved. The frozen part also contributes to immunofluorescent and enzyme immunochemical research. Another useful indicator is certain carbohydrates and lipids in the dyed tissue. How long does a frozen section take? A frozen section is placed on a freezing microtome machine where the bottom of the sample is frozen within seconds. A razor-thin slice of tissue is extracted from the frozen section, prepared on a slide and placed under the microscope for review. In many other medical centers, this process takes at least 24 hours to complete. Why is Frozen Section Important? It is an important feature that is needed i...

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Paraffin Embedded Tissue Processing

Introdution 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 cell 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. Why Leading Biology? At Leading Biology, we custom protein purification design for every single protein to ensure the production and recovery rate as high as possible. Working with us, you will get stability, and it means...

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Transgenic Plants Construction

Introduction 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 improves the nutritional quality of the plants, but also increases 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. Why Leading Biology? At Leading Biology, we custom protein purification design for every single protein to ensure the production and recovery rate as high as possible. Working with us, you will get stability, and it means a reliable partner to help streamline your R&D process. Working with us, you will get the guarante...

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Microorganisms Gene Modification Services

Introduction 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. Why Leading Biology? At Leading Biology, we custom protein purification design for every single protein to ensure the production and recovery rate as high as possible. Working with us, you will get stability, and it means a reliable partner to help streamline your R&D process. Working with us, you will get the guaranteed service to accommodate your requirements. · Vigorous quality control system to ensure the required quality and re...

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CRISPR-CAS Technology

Introduction 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 defense 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 th...

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TALEN Technology

Introduction 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. ...

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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. Why Leading Biology? At Leading Biology, we custom protein purification design for every single protein to ensure the production and recovery rate as high as possible. Working wi...

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Tetracycline Induced Gene knockout/knockin

Introduction 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 s...

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