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By M. Miguel. University of Illinois at Chicago.

Lysozyme is effective principally against of microbes order 25 mg benadryl visa allergy shots louisville ky, which constitutes a cornerstone of constituitive Gram-positive cocci cheap benadryl 25 mg online allergy medicine for juniper, but it may facilitate the effect of anti- defense against infection benadryl 25 mg visa allergy treatment dallas. Adherence of opsonized bacteria to the phago- cyte cell surface facilitates phagocytosis. Macrophage Opsonins bind to bacteria, erythrocytes, or other particles to increase their susceptibility to phagocytosis. They are host proteins that coat a pathogenic microorganism or macromol- Opsonization ecule to make it bind more readily to phagocyte receptors, Antibacterial thereby enhancing phagocytosis. Opsonins include antibod- Ab (opsonin) ies such as IgG3, IgG1, and IgG2 that are specifc for epitopes on the particle surface. Following interaction, the Fc region of the antibody becomes anchored to Fc receptors on phagocyte surfaces, thereby facilitating phagocytosis of the particles. In contrast to these so-called heat-stable antibody opsonins are the heat-labile products of complement activation such as C3b or C3bi, which are linked to particles by transacyla- tion with the C3 thiolester. C3b combines with complement Efficient phagocytosis receptor 1 and C3bi combines with complement receptor 3 on phagocytic cells. Besides immunoglobulins of the above mentioned isotypes, and complement proteins, other opsonic complement intermediates include iC3b and C4b. Opsonins facilitate phagocytosis of particulate antigens by neutro- phils or macrophages. Other substances that act as opsonins include the basement membrane constituent, fbronectin (Figure 24. They contain both Fibronectin is an adhesion-promoting dimeric glycoprotein primary or azurophilic granules and secondary or specifc of relatively high mol wt found abundantly in the connective granules that serve as reservoirs for the digestive and hydro- tissue and basement membrane. Fibronectin is also present in plasma and on normal Macrophages that serve as scavengers ingesting debris left by cell surfaces. Approximately 20 separate fbronectin chains neutrophils killed by the microorganisms they phagocytized, are known. Fibronectin is comprised of two 250-kDa subunits joined near their carboxy A secondary granule is a structure in the cytoplasm of terminal ends by disulfde bonds. The amino acid residues in polymorphonuclear leukocytes that contains vitamin B12- the subunits vary in number from 2145 to 2445. Histamine, platelet-activating factor, and heparin are may also serve as an opsonin and function as an adhesion present in the secondary granules of basophils. Intensive care patients often Phagocytic cells are polymorphonuclear neutrophils and lose fbronectin from their pharynx causing alteration of the eosinophils as well as macrophages (the mononuclear phago- normal fora with colonization by coliforms. Intracellular microorganisms Macrophages Mononuclear phagocytes originate from stem cells in the bone (i. Liver macrophages are termed Kupffer cells, whereas those in the lung are alveolar mac- microbial infection (Figure 24. The microglia represent macrophages of the central trophils and occasionally eosinophils appear frst in areas nervous system, whereas histiocytes represent macrophages of of acute infammation followed later on by macrophages. Tissue stem cells are monocytes that have Chemotactic factors, including N-formyl-methionyl-leucyl- wandered from the blood into the tissues and may differenti- phenylalanine (f-Met-Leu-Phe) are released by actively mul- ate into macrophages. Different such protein molecules as C3 via complement receptor 1 and types of infectious agents may stimulate different types of complement receptor 3, and IgG and IgE through Fcγ and Fcε cellular response. Mononuclear phago- as opsonins coat microorganisms or other particles and make cytes secrete a rich array of molecular substances with various them more delectable to phagocyte cells. A few of these include interleukin-1; tumor necrosis specifc substances such as complement component C3b, as factor α; interleukin-6; C2, C3, C4, and factor B complement well as specifc antibodies located in the IgG or IgG3 frac- proteins; prostaglandins; leukotrienes; and other substances. Capsules enable microorganisms such as pneumococci and Hemophilus to resist phagocytosis. Mononuclear phagocytes include monocytes in the blood and macrophages in the tissues which have cell surface receptors Azurophil granules Specifc granules for Fcγ and C3b. They are also able to phagocytize micro- (Primary granules) (Secondary granules) organisms coated with opsonins and kill many but not all Bacterial permeability- microorganisms during the process. Particle ligands unite Collagenase with numerous receptors on the surface of the phagocyte C5a receptors in a “zippering” effect and cause polymerization of actin, Gelatinase invagination of the plasma membrane and sequestration of Lactoferrin the particle into an intracellular vesicle termed a phagosome. Damaged cells are also phagocy- other cells such as fbroblasts may show phagocytic proper- tized by nonimmunologic mechanisms. Nonimmunologic phagocytosis refers to the Phagocytosis involves several steps attachment, internaliza- ingestion of inert particles such as latex beads, or of other tion, and digestion (Figure 24. The initiation of ingestion particles that have been modifed by chemical treatment or is known as the “zipper mechanism. Fused granule IgG Bacterium (azurophil) membrane C3b IgG receptor C3b receptor Specific (secondary) granule Cationic microbial proteins Azurophilic (primary) Acidic phagolysosome granule contains short-chain fatty acids 2. Immunity against Microorganisms 723 particle is engulfed within a fragment or plasma membrane such as Mycobacteria or Listeria are not killed merely by and forms a phagocytic vacuole. This vacuole fuses with the ingestion and may remain viable unless there is adequate primary lysosomes to form the phagolysosome in which the cell-mediated immunity induced by γ interferon activation of lysosomal enzymes are discharged and the enclosed material macrophages. Remnants of indigestible material can be recog- nized subsequently as residual bodies. The process is associ- Phagocytic dysfunction may be due to either extrinsic or ated with stimulation of phagocyte metabolism. The extrinsic variety encompasses opsonin defciencies secondary to antibody or complement factor def- Phagocytic dysfunction may be due to either extrinsic or ciencies, suppression of phagocytic cell numbers by immu- intrinsic defects. The extrinsic variety encompasses opsonin nosuppressive agents, corticosteroid-induced interference defciencies secondary to antibody or complement factor def- with phagocytic function, neutropenia, or abnormal neutro- ciencies, suppression of phagocytic cell numbers by immuno- phil chemotaxis. Intrinsic phagocytic dysfunction is related suppressive agents, corticosteroid-induced interference with to defciencies in enzymatic killing of engulfed microorgan- phagocytic function, decreased neutrophils through antineu- isms. Examples of the intrinsic disorders include chronic trophil autoantibody; and abnormal neutrophil chemotaxis granulomatous disease, myeloperoxidase defciency, and glu- as a consequence of complement defciency or abnormal cose-6-phosphate dehydrogenase defciency. Intrinsic phagocytic dysfunction is of phagocytic dysfunction include increased susceptibility to related to defciencies in enzymatic defciencies that partici- bacterial infections but not to viral or protozoal infections. Selected phagocytic function disorders may be associated These intrinsic disorders include chronic granulomatous dis- with severe fungal infections. Severe bacterial infections ease, characterized by defects in the respiratory burst path- associated with phagocytic dysfunction range from mild skin way, myeloperoxidase defciency, and glucose-6-phosphate infections to fatal systemic infections. Consequences of phago- cytic dysfunction include increased susceptibility to bacterial Chemotaxis is the process whereby chemical substances infections but not to viral or protozoal infections. The orientation and phagocytic function disorders may be associated with severe movement of cells in the direction of a chemical’s concen- fungal infections. Severe bacterial infections associated with tration gradient is positive chemotaxis, whereas movement phagocytic dysfunction range from mild skin infections to away from the concentration gradient is termed negative fatal systemic infections. Substances that induce chemotaxis are referred to as chemotaxins and are often small molecules, such as Phagocytosis may involve nonimmunologic or immunologic C5a, formyl peptides, lymphokines, bacterial products, leu- mechanisms. These particles that have been modifed by chemical treatment or cells move into infammatory agents by chemotaxis. Damaged cells are also phagocytized by chamber device called a Boyden chamber is used to mea- nonimmunologic mechanisms.

B cell maturation takes place in the bone Signals transduced by the pTαβ receptor facilitate expression marrow and T cell maturation is governed by the thymus purchase generic benadryl on line allergy treatment xerosis. The rate of release of thymocytes from the thy- become either helper or cytolytic cells prior to their jour- mus is markedly increased following antigenic stimulation buy benadryl line allergy shots in dogs. It is the pathway in which the T cell receptor β chain functional genes encoding variable regions of antigen 314 Atlas of Immunology discount benadryl 25mg on-line allergy xyzal, Third Edition receptors are produced during lymphocyte development. Also cytes with T cell receptors that are not functional undergo called somatic rearrangement. They represent an intermediate step cell-culture product capable of facilitating thymocyte growth. Immature double-negative bone marrow graft cells have Pre-T cells represent a stage in the maturation of T lympho- stem cell features. They membrane T cell receptor α-like chain manifested exclusively also express T cell receptors and are exposed to selection by double negative thymocytes. Positively selected cells are the only ones permitted to continue their maturation. Prothymocytes (pre-T cells) differentiate in the thymus B cells with low affnity for self antigen receive survival sig- microenvironment. There are four thymic peptide hormones termed thymulin, thymosin α, thymosin β, and thy- the differential signaling hypothesis is a proposal which mopoietin. These hormones are signifcant in T lymphocyte considers that antigens that differ qualitatively might mediate proliferation and differentiation. Direct interaction with the positive and negative selection of thymic T lymphocytes. It long-lived cells acquire new characteristics and are called can also be employed to add homopolymer tails. The thymus is rich in specifc areas of the peripheral lymphoid organs where they TdT, which is also present in the bone marrow. TdT inserts continue to differentiate through a process driven by an anti- a few nucleotides in T cell receptor genes and immunoglob- gen. TdT is present both in the nuclear and soluble fractions of thymus and bone marrow. In mice, two forms of TdT can be sepa- undergo clonal deletion (apoptosis) or clonal anergy (inacti- rated from a preparation of thymocytes. Autoreactive to 6 to 8 months of age; in others, it declines immediately B cells undergo a similar process in the bone marrow. These cells become O positive after treatment with a thymic Positive selection is the pathway in the thymus that pro- hormone, thymopoietin, suggesting that they are precursors motes the survival of immature T cells with receptors that of thymocytes. TdT is detectable in T cell leukemia, 90% of com- mon acute lymphoblastic leukemia cases, and half of acute Early B undifferentiated leukemia cells. Approximately one-third of lineage precursor Subcortical Bone marrow chronic myeloid leukemia cells in blast crisis and a few cases thymocyte Large Tymus of pre-B cell acute lymphoblastic leukemia cases show cells pre-B cell that are positive for TdT. In blast cri- B cell sis, some cells may simultaneously express lymphoid and Intermediate Suppressor/ B cell Inducer Cytotoxic myeloid markers. Indirect immunofuorescence procedures T cell T cell Blood can demonstrate TdT in immature B and T lymphocytes. Helper Mature Suppressor It inserts nontemplated nucleotides (N-nucleotides) into the T cell T cell B cell junctions between gene segments during T cell receptor and Active B cell Activated T cell immunoglobulin heavy-chain gene rearrangement. Immunoblast Lymph node Thymus cell differentiation is stem cell maturation and figure 9. Antigen driven T Lymphoblast T cell Thymus cell education refers to thymus cell differentiation. They are usually proteins, protein-nuclear protein conjugates, glycoproteins, or lipoproteins. Thymus-dependent antigens include proteins, poly- peptides, hapten–carrier complexes, erythrocytes, and many figure 9. T cells produce cytokines and cell sur- T-independent antigen is a thymus-independent antigen. Humoral immune responses to show only minor heavy chain isotype switching or affnity T-dependent antigens are associated with isotype switching, maturation, both of which require helper T cell signals. It macrophages are depleted, no antibody response develops is the need for hapten and a carrier to be linked physically against them. There is a lack of somatic hypermutation rather than merely mixed together to stimulate a secondary and memory B cell development. Specifcally, which are usually polysaccharides comprised of repetitive these include the paracortical areas of lymph nodes, elements, interact with B cell receptors but are incapable of the zone between nodules and Peyer’s patches, and the completely activating B cells in the absence of cytokines center of splenic Malpighian corpuscles. Proof that these anatomical sites are other lymphoid organs where T lymphocytes localize thymus-dependent areas is provided by the demonstration preferentially. Likewise, humans or animals T cell areas are regions of secondary tissues occupied pre- with thymic hypoplasia or congenital aplasia of the thymus dominantly by T lymphocytes. T cell help is the facilitation through cytokines and costim- Traffc area refers to thymus-dependent area. These saccharide of the pneumococcus, a dextran polyvinyl hooter, include antigen recognition, costimulation, and cytokine sig- or a bacterial lipopolysaccharide. In immunology, it was used as an are now enumerated by the use of monoclonal antibodies and early method to enumerate T cells. The antigen is also found on interdigitating cells, fetal B cells, and Langerhans cells. These chains are associated S with β2-microglobulin and the antigen is thus analogous to S classical histocompatibility antigens but coded for by a dif- ferent chromosome. More recent studies have shown that the molecule is coded for by at least fve genes on chromosome 1, three of which produce recognized polypeptide products. Rat tissue, endothelium), as well as on many white cell popula- recombinant form expressed in Chinese hamster ovary cells. T 17 cells are of central importance to the pathogen- H H esis of infammatory diseases and autoimmune diseases. An inducer T lymphocyte is a cell required for the ini- tiation of an immune response. Cytotoxic T cells are T lymphocytes that fatally injure other including perforin/granzyme, FasL/Fas, tumor necrosis factor + cells. Once activated, Tc cells become cytotoxic through the T cell receptor on cells of the host infected by T lymphocyte effector cells that fatally injure target cells viruses or that have become neoplastic. Following recogni- via perforin/granzyme-mediated cytotoxicity or through tion and binding, death of the target cell occurs a few hours secreted cytotoxic cytokines. Cytotoxicity assays are techniques to quantify the action Immunological suicide: the use of an antigen deliberately of immunological effector cells in inducing cytolysis of tar- labeled with high-dose radioisotope to kill a subpopulation of get cells.

Based on the patient’s clinical presentation order genuine benadryl line allergy index st louis, additional testing may be indicated buy discount benadryl 25mg allergy symptoms and pregnancy, including a complete blood count buy 25mg benadryl free shipping allergy forecast today, erythrocyte sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging (sagittal view) of the calf depicting the rupture and the hematoma in the gastrocnemius muscle. Composite longitudinal scan of the medial gastrocnemius (G) shows partial disruption (arrows) at the myotendinous junction. An anechoic hematoma (H) is seen dissecting between the gastrocnemius and soleus (S) muscles. Musculoskeletal ultrasound: an alternative imaging modality for sports-related injuries. However, coexisting bursitis or tendinitis of the knee and distal lower extremity from overuse or misuse may confuse the diagnosis. In some clinical situations, consideration should be given to primary or secondary tumors involving the affected region. Nerve entrapments of the lower extremity secondary to compression by massive hematoma formation or ruptured Baker’s cysts (especially in anticoagulated patients) can also confuse the diagnosis. A linear high-frequency ultrasound transducer is placed in a longitudinal orientation over the lateral aspect of the posterior knee at the level of the previously identified joint space and an ultrasound survey scan is obtained (Fig. The lateral femoral condyle and the lateral head of the gastrocnemius muscle are identified (Fig. The extent of the insertion of the lateral head of the gastrocnemius muscle is evaluated for tear, hematoma, and the presence of a fabella, which will appear as an ovoid, smooth appearing hyperechoic mass lying beneath it (Fig. The medial joint space is then evaluated and the medial femoral epicondyle and the medial head of the gastrocnemius muscle are then identified and evaluated for tear, hematoma, rupture, and abnormal mass in a manner analogous to the evaluation of the lateral head of the muscle (Fig. The extent of both the medial and the lateral muscle is then evaluated by slowly moving the ultrasound transducer inferiorly until they join with the soleus muscle to form the Achilles tendon. The medial and lateral muscle is then evaluated for tear, hematoma, rupture, and abnormal mass (Figs. Color Doppler may help identify acute injury as well as compromise of the popliteal artery and vein (Figs. Proper longitudinal position of the ultrasound transducer over the lateral posterior knee at the level of the joint space for evaluation of the lateral head of the gastrocnemius muscle. Longitudinal ultrasound image demonstrating the lateral femoral condyle and lateral head of the gastrocnemius muscle. Longitudinal ultrasound image demonstrating the medial femoral condyle and medial head of the gastrocnemius muscle. A hematoma (H) is seen between the medial gastrocnemius (G) and soleus (S) muscles, most likely related to a tennis leg injury that occurred a few months earlier. Musculoskeletal ultrasound: an alternative imaging modality for sports- related injuries. A thin hematoma (white arrowheads) lies between the aponeurosis of gastrocnemius and normal soleus muscle. A large hematoma (white arrowheads) lies between the torn gastrocnemius and normal soleus muscle. Transverse (A) and longitudinal (B) ultrasound images demonstrating a large hematoma within the torn gastrocnemius muscle. High-frequency color Doppler ultrasound images of gastrocnemius hematoma following trauma or exercise. A: Three days after symptoms occurred, one can see anechoic signals with mixed irregular hypoechoic signals and partially nonintact muscle fibers with defects occupied by hematomas. B: Seven hours after symptom occurrence, an oval isoechoic signal is visible in the posterior of gastrocnemius muscle. The hematoma exhibited high tension, with a hyperechoic boundary and enhanced signal from the posterior of the hematoma. Differential diagnosis of isolated calf muscle vein thrombosis and gastrocnemius hematoma by high-frequency ultrasound. High-frequency color Doppler ultrasound images of gastrocnemius hematoma induced by oral anticoagulant use. A: One day after symptom occurrence, hypoechoic lesions with irregular anechoic regions are visible. B: Six days after symptom occurrence, soft tissues exhibit a spindle shape with irregular hypoechoic signals. The surrounding muscle was extruded, and an enhanced hyperechoic signal was observed between the muscle and hematoma. Differential diagnosis of isolated calf muscle vein thrombosis and gastrocnemius hematoma by high-frequency ultrasound. A high index of suspicion for the insidious onset of lower extremity compartment syndrome or deep venous thrombosis is important to avoid disaster. The articular surfaces are covered with hyaline cartilage, which are susceptible to arthritis. The joint is completely surrounded by a dense capsule that provides support to the joint. The majority of strength to the ankle joint is provided by the major ligaments which include the deltoid, anterior talofibular, calcaneofibular, and posterior talofibular ligaments (Fig. The joint capsule is lined with a synovial membrane that attaches to the articular cartilage and may give rise to bursae. In addition to arthritis, the joint is susceptible to the development of tendinitis, bursitis, fractures, and disruption of the ligaments, cartilage, and tendons. The ankle joint is completely surrounded by a dense capsule that provides support to the joint. Most of the strength of the ankle joint is provided by the deltoid, anterior talofibular, calcaneofibular, and posterior talofibular ligaments. Osteoarthritis of the joint is the most common form of arthritis that results in ankle joint pain and functional disability, with rheumatoid arthritis and posttraumatic arthritis also causing arthritis of the ankle joint. The ankle joint is the most commonly injured joint in the human body, with sports injuries from basketball, football, tennis, and cross country running being frequent causes of pain and functional disability. Less common causes of arthritis-induced ankle joint pain include the collagen vascular diseases, infection, villonodular synovitis, and Lyme disease (Fig. Acute infectious arthritis of the ankle joint is best treated with early diagnosis, with culture and sensitivity of the synovial fluid, and prompt initiation of antibiotic therapy. The collagen vascular diseases generally manifest as a polyarthropathy rather than a monoarthropathy limited to the ankle joint, although ankle pain secondary to the collagen vascular diseases responds exceedingly well to ultrasound-guided intra-articular injection of the ankle joint. Activity, especially involving dorsiflexion of the ankle joint makes the pain worse, with rest and heat providing some relief. Sleep disturbance is common with awakening when the patient rolls over onto the affected ankle.

A novel high-speed imaging randomly in the human retina order generic benadryl line allergy testing jersey uk, and are absent in the central instrument has recently been developed to examine the fovea (the central part of the retina) 25 mg benadryl free shipping allergy forecast harrisburg pa. Previously buy 25mg benadryl free shipping allergy symptoms glands, the blue ble to rapidly scan the photoreceptor mosaic over a large and (red + green) cone mosaic was determined using area of the living human retina. Distinguishing diagnosis of photoreceptor abnormalities and of determin­ red from green cones was not feasible by these methods ing the genotype-phenotype relationships in inherited because of the high degree of sequence homology between retinal diseases. Ratio of red to green c o n e s in the retina J Neurosci 2 0 0 5 :2 5 :9 6 6 9 -7 9. They are referred to as having trichromatic quency relative to Caucasians is mainly due to a lower fre­ color vision. Individuals who lack functional red or green quency (~2%) of deuteranomalv among the Japanese. In achromatopsia, there may match the color of a test light by mixing two primaries only be complete absence of cone responses, causing very poor and, therefore, have dichromatic color vision. Dichromacy or no color discrimination, associated with low visual occurs in approximately 2% ofCaucasian males. This is photoreceptor combinations of males with normal and inherited as an autosomal recessive trait. Patients with severe color vision deficiencies and the corresponding color atypical rod monochromacy have cone pigments but they discrimination capacities are shown in Figure 30. In blue cone monochromacy, or is anomalous trichromacy, which occurs in approximately X-linked incomplete achromotopsia,M-55 both red and 5% of males of European origin (Table 30. Anomalous green cones are nonfunctional, while blue cone function is trichromats are believed to have three classes of photore­ preserved. The color perception of color-defective observers has been studied in a few individ­ uals who for unknown reasons were color-defective in one N orm al eye only. Color per­ ception of dichromatic deuteranopes in general conform to D euteranopic this general pattern. On the other hand, dichromatic protano- Tritanopic pia appears as a more severe defect than deuteranopia. A Protanopes confuse not only red, yellow, and green, as in deuteranopia, but also deep red, dark brown, or even black B C M and have particular problems with red color perception. Green and red are not absent males and the corresponding color discrimination phenotype (rainbow). Shown are the absorption spectra of blue, green, and red photoreceptor cones in but appear less intense. Color vision-defective persons, the retinas of m ales with normal color vision (trichromatic). Dichromatic including dichromats, usually have no problem naming (protanopes and deuteranopes). Individuals with achrom atopsia (not shown) also se c only black and white colors. We discovered a common single amino acid poly­ morphism (62% Ser, 38% Ala) at residue 180 of the red i i i i i i f> Normal photopigment in the Caucasian population. In addition, approximately 15% of males had Ser instead of Ala in some I 1 1 1 1 1 I > D eutan of their green pigment genes. The pigment, we hypothesized that this polymorphism may number of green pigment genes that follow the single red pigment gene account for some of the variations observed in both normal vanes (1 -6 ) in the population. Eech gene is about 15 kb in length, and these genes are separated by 25 Kb of intergenic regions. Fifty Caucasian males with (locus control region) is essential for expression of both the red and normal color vision were tested for the hypothesis that the green pigment genes in the array. The diagram includes six exons two major groups in the distribution of color matching (squares). The red and green pigment genes {including introns) and the could be explained by the above Ser/Ala polymorphism. The gene duplication event that gave rise to the red and green pigment genes of the New World primates must have w occurred after separation of the New and Old World lin­ «> я eages. It is interesting to note that despite the presence of £ only the blue and red-green pigment genes in the New ф -О World primates, a limited degree of trichromatic color E vision has been observed in females who arc heterozygotes for two alleles of the single X-chromosome-linked pig­ ment gene that encode pigments of different absorption maxima. O f great interest was the finding that one genus of New Word monkeys (Alouatta, the howler monkey) has 0. Defective colour vision Subtle variation in color perception in the red-green region associated with a m issen se mutation in the human green visual pigment of the spectrum has been observed among individuals gene. Later, duced into the population a variety of chimeric pigments Sanocki and colleagues*1,85 showed that the Ser/Ala poly­ with different absorption maxima, depending on the point morphism at position 180 of the red pigment genc underlies of fusion between the red and green pigment genes. This is somewhat analogous to pigment genes, but more importantly will convert a red pig­ the situation in the New World monkeys, who have only a ment into a green-like pigment and vice versa. The struc­ single X-chromosome-encodcd pigment genc with sev­ ture of hybrid genes observed among color-deficient eral alleles, where females heterozygous for two alleles of individuals and the absorption maxima of the encoded pig­ this genc achieve trichromacy, while males and homozy­ ments are shown in Figure 30. Note that recom­ mined the absorption spectra of recombinant human red binations in intron 5 would not result in a hybrid encoding pigments that differed in sequence by having only Scr or a new pigment, since the exon 6 of the red and green pig­ Ala at position 180. The significance of hybrid genes in Defects determining the color vision phenotype will be discussed the relatively common (8% of Caucasian males) red-green below in conjunction with expression of red and green color vision defects in which the red or the green cones arc pigment genes in the retina. These defects arc associated with loss of function of either the red or the green photopigmcnts, or with the formation of red- 8 S - <4 N green hybrid pigments with shifted absorption maxima. СЛ > t- Unequal homologous recombination, to which this locus is highly predisposed, is the driving force behind both the N orm als loss of pigment genes and the formation of hybrid pigment genes. The X-linked mode of inheritance, the lack of selec­ tion against individuals with defective color vision, and the high frequency of unequal recombination between the red and green pigment genes arc believed to be responsible 1 I I 1 I I j > for the high frequency of these defects among males. Deletion of green pigment genes results from unequal recombination or crossing-over events that occur within ngure 30. The three amino acid residues that make a major contribution to residues that contribute to the majority of the difference the spectral difference between the red and green pigment genes are (30 nm) in absorption maxima between the red and green indicated. G4-R5 represents a hybrid gene with the first four exons being G reen-S eries green and last two exons being 20 red. Deuteranopic individuals have no functional green- spectral sensitivity of the photopigments. Considerable variation in the 5 of the red opsin gene was predicted, since it contains two severity of anomalous trichromacy has been observed. Using о rx «л о £■ 5Й Southern blot analysis, which detects major gene rearrange­ К «в 55 To h < u- < ЛЛтах(Пт) C o lo r vision ments, they found that among individuals with protan 1 V. Among deutans, deuteranopia (dichromacy) was associated with gene arrays comprising A Protanom alous 1 1 1 — ►........................ Subsequently, we determined the gross struc­ difference in spectra between the red and green pigments are indicated. There is good experimental evidence that In a study of such female carriers of anomalous trichro­ heterozygotes arc mosaics for normal and abnormal color macy, Jordan and Mollon119 provided evidence that some vision in their retinas.