Viral vectorViral vectors are tools commonly used by molecular biologists to deliver genetic material into cells. This process can be performed inside a living organism (in vivo) or in cell culture (in vitro). Viruses have evolved specialized molecular mechanisms to efficiently transport their genomes inside the cells they infect. Delivery of genes or other genetic material by a vector is termed transduction and the infected cells are described as transduced. Molecular biologists first harnessed this machinery in the 1970s.
Gene deliveryGene delivery is the process of introducing foreign genetic material, such as DNA or RNA, into host cells. Gene delivery must reach the genome of the host cell to induce gene expression. Successful gene delivery requires the foreign gene delivery to remain stable within the host cell and can either integrate into the genome or replicate independently of it. This requires foreign DNA to be synthesized as part of a vector, which is designed to enter the desired host cell and deliver the transgene to that cell's genome.
Facial nerveThe facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue. The nerve typically travels from the pons through the facial canal in the temporal bone and exits the skull at the stylomastoid foramen.
Facial nerve paralysisFacial nerve paralysis is a common problem that involves the paralysis of any structures innervated by the facial nerve. The pathway of the facial nerve is long and relatively convoluted, so there are a number of causes that may result in facial nerve paralysis. The most common is Bell's palsy, a disease of unknown cause that may only be diagnosed by exclusion of identifiable serious causes. Facial nerve paralysis is characterised by facial weakness, usually only in one side of the face, with other symptoms possibly including loss of taste, hyperacusis and decreased salivation and tear secretion.
Neurotrophic factorsNeurotrophic factors (NTFs) are a family of biomolecules – nearly all of which are peptides or small proteins – that support the growth, survival, and differentiation of both developing and mature neurons. Most NTFs exert their trophic effects on neurons by signaling through tyrosine kinases, usually a receptor tyrosine kinase. In the mature nervous system, they promote neuronal survival, induce synaptic plasticity, and modulate the formation of long-term memories.
NeuronWithin a nervous system, a neuron, neurone, or nerve cell is an electrically excitable cell that fires electric signals called action potentials across a neural network. Neurons communicate with other cells via synapses - specialized connections that commonly use minute amounts of chemical neurotransmitters to pass the electric signal from the presynaptic neuron to the target cell through the synaptic gap. The neuron is the main component of nervous tissue in all animals except sponges and placozoa.
NeurotrophinNeurotrophins are a family of proteins that induce the survival, development, and function of neurons. They belong to a class of growth factors, secreted proteins that can signal particular cells to survive, differentiate, or grow. Growth factors such as neurotrophins that promote the survival of neurons are known as neurotrophic factors. Neurotrophic factors are secreted by target tissue and act by preventing the associated neuron from initiating programmed cell death – allowing the neurons to survive.
VirotherapyVirotherapy is a treatment using biotechnology to convert viruses into therapeutic agents by reprogramming viruses to treat diseases. There are three main branches of virotherapy: anti-cancer oncolytic viruses, viral vectors for gene therapy and viral immunotherapy. These branches use three different types of treatment methods: gene overexpression, gene knockout, and suicide gene delivery. Gene overexpression adds genetic sequences that compensate for low to zero levels of needed gene expression.
Cranial nervesCranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing. The cranial nerves emerge from the central nervous system above the level of the first vertebra of the vertebral column. Each cranial nerve is paired and is present on both sides.
Vector (molecular biology)In molecular cloning, a vector is any particle (e.g., plasmids, cosmids, Lambda phages) used as a vehicle to artificially carry a foreign nucleic sequence – usually DNA – into another cell, where it can be replicated and/or expressed. A vector containing foreign DNA is termed recombinant DNA. The four major types of vectors are plasmids, viral vectors, cosmids, and artificial chromosomes. Of these, the most commonly used vectors are plasmids. Common to all engineered vectors are an origin of replication, a multicloning site, and a selectable marker.
Motor neuronA motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands. There are two types of motor neuron – upper motor neurons and lower motor neurons. Axons from upper motor neurons synapse onto interneurons in the spinal cord and occasionally directly onto lower motor neurons.
Facial musclesThe facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. These muscles are also called mimetic muscles. They are only found in mammals, although they derive from neural crest cells found in all vertebrates. They are the only muscles that attach to the dermis. The facial muscles are just under the skin (subcutaneous) muscles that control facial expression.
Schwann cellSchwann cells or neurolemmocytes (named after German physiologist Theodor Schwann) are the principal glia of the peripheral nervous system (PNS). Glial cells function to support neurons and in the PNS, also include satellite cells, olfactory ensheathing cells, enteric glia and glia that reside at sensory nerve endings, such as the Pacinian corpuscle. The two types of Schwann cells are myelinating and nonmyelinating. Myelinating Schwann cells wrap around axons of motor and sensory neurons to form the myelin sheath.
Mauthner cellThe Mauthner cells are a pair of big and easily identifiable neurons (one for each half of the body) located in the rhombomere 4 of the hindbrain in fish and amphibians that are responsible for a very fast escape reflex (in the majority of animals – a so-called C-start response). The cells are also notable for their unusual use of both chemical and electrical synapses. Mauthner cells first appear in lampreys (being absent in hagfish and lancelets), and are present in virtually all teleost fish, as well as in amphibians (including postmetamorphic frogs and toads).
Sixth nerve palsySixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI (the abducens nerve), which is responsible for causing contraction of the lateral rectus muscle to abduct (i.e., turn out) the eye. The inability of an eye to turn outward, results in a convergent strabismus or esotropia of which the primary symptom is diplopia (commonly known as double vision) in which the two images appear side-by-side. Thus, the diplopia is horizontal and worse in the distance.
Viral transformationViral transformation is the change in growth, phenotype, or indefinite reproduction of cells caused by the introduction of inheritable material. Through this process, a virus causes harmful transformations of an in vivo cell or cell culture. The term can also be understood as DNA transfection using a viral vector. Viral transformation can occur both naturally and medically. Natural transformations can include viral cancers, such as human papillomavirus (HPV) and T-cell Leukemia virus type I.
Adult neurogenesisAdult neurogenesis is the process in which neurons are generated from neural stem cells in the adult. This process differs from prenatal neurogenesis. In most mammals, new neurons are born throughout adulthood in two regions of the brain: The subgranular zone (SGZ), part of the dentate gyrus of the hippocampus, where neural stem cells give birth to granule cells (implicated in memory formation and learning). The subventricular zone (SVZ) of the lateral ventricles, which can be divided into three microdomains: lateral, dorsal and medial.
NeuroregenerationNeuroregeneration involves the regrowth or repair of nervous tissues, cells or cell products. Neuroregenerative mechanisms may include generation of new neurons, glia, axons, myelin, or synapses. Neuroregeneration differs between the peripheral nervous system (PNS) and the central nervous system (CNS) by the functional mechanisms involved, especially in the extent and speed of repair. When an axon is damaged, the distal segment undergoes Wallerian degeneration, losing its myelin sheath.
RodentRodents (from Latin rodere, 'to gnaw') are mammals of the order Rodentia (rouˈdEnS@), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity.
Growth factorA growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for regulating a variety of cellular processes. Growth factors typically act as signaling molecules between cells. Examples are cytokines and hormones that bind to specific receptors on the surface of their target cells. They often promote cell differentiation and maturation, which varies between growth factors.
