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The skin of vertebrates is the outermost organ of the body and serves as the first line of defense against external aggressions. In contrast to mammalian skin, that of teleost fish lacks keratinization and has evolved to operate as a mucosal surface containing a skin-associated lymphoid tissue (SALT). Thus far, IgT representing the prevalent Ig in SALT have only been reported upon infection with a parasite. However, very little is known about the types of B cells and Igs responding to bacterial infection in the teleost skin mucosa, as well as the inductive or effector role of the SALT in such responses. To address these questions, in this study, we analyzed the immune response of trout skin upon infection with one of the most widespread fish skin bacterial pathogens, Flavobacterium columnare. This pathogen induced strong skin innate immune and inflammatory responses at the initial phases of infection. More critically, we found that the skin mucus of fish having survived the infection contained significant IgT- but not IgM- or IgD-specific titers against the bacteria. Moreover, we demonstrate the local proliferation and production of IgT+ B cells and specific IgT titers, respectively, within the SALT upon bacterial infection. Thus, our findings represent the first demonstration that IgT is the main Ig isotype induced by the skin mucosa upon bacterial infection and that, because of the large surface of the skin, its SALT probably represents a prominent IgT-inductive site in fish.

To our knowledge, there are no published reports of heat exhaustion and pesticide exposure in a labor trafficked patient in the literature. Here we represent the case of J.C.J.L., who was labor trafficked. He presented to a local emergency department with heat exhaustion and pesticide exposure related to working conditions in a Mississippi corn field. Unfortunately, while he received medical treatment, his labor trafficking condition was missed. Emergency departments should be equipped to assess for human trafficking and connect trafficked persons with the resources they need. Emergency physicians should maintain a high index of suspicion for human trafficking among migrant workers presenting with occupation-related complaints.

Traditional image contour tracking algorithm has low tracking accuracy. To solve this problem, an object contour tracking algorithm based on local significant edge features in complex background is proposed. In the algorithm, the projective invariant is firstly introduced, to construct the geometric information descriptor between the edge positions of the infrared image, and set up the histogram of the feature number of each target contour. The geometric similarity between the features is measured by the pasteurized coefficient, the edge features of the neighbourhood around the object contour are established, and the object contour with significant features in the edge of the image is searched. Combining Shape-context operator with edge feature, the feature description vector can be formed, and Euclidean distance is defined to track measurement function. Using this function, the selected object contour is tracked preliminarily. The random consistency checking algorithm is used to eliminate the false tracking feature points and obtain the best tracking value of the object contour, thus the infrared image’s object contour tracking is carried out in the complex background. Experimental simulation shows that the proposed algorithm has high tracking accuracy and effectively improves the quality of infrared image analysis.

Immunoglobulins (Igs) are crucial components of the immune response in vertebrates including teleost fish. In the present study, we firstly cloned the full-length cDNA of IgT and IgD heavy chain genes in largemouth bass (Micropterus salmoides), one of the important farmed fish species in China. Importantly, IgH locus covering τ, μ and δ genes of largemouth bass was also illustrated. The genomic organization of the IgH locus presented as V26-D3-J5-Cτ-D6-J6-Cμ-Cδ, which was similar with some other teleost fish. Furthermore, The IgH locus of largemouth bass contained 26 VH segments and they belonged to three subgroups, whose members showed a greater than 80% amino acid identity. This founding would allow us to gain further insight into the evolution of adaptive immune system. To further understanding the immune response of immunoglobulins, we successfully constructed the infection model with bacteria (GFP–Flavobacterium columnare G4). Our results showed the expression of IgM was up-regulated in head kidney, and the expression of IgT was significantly induced mainly in skin and gill, suggesting their potential roles in systemic and mucosal immune response to bacterial infection, respectively.

The skin of vertebrates is the outermost organ of the body and serves as the first line of defense against external aggressions. In contrast to mammals, the skin of early vertebrates like fish, lacks keratinization and has evolved to operate as a mucosal surface. As such, it has been shown to contain a skin-associated lymphoid tissue (SALT) in the epidermis. Prior to the discovery of IgT as a key mucosal immunoglobulin (Ig) in fish, several studies reported IgM-specific titers in the skin mucus upon pathogenic infection or vaccination. In contrast, a recent report showed IgT being the main Ig responding in the skin upon parasitic challenge. Whether IgT is the main Ig isotype elicited in the skin against bacterial pathogens, and whether such responses are locally induced within the SALT are important questions that remain unanswered. Here we analyzed the immune response of trout skin upon infection with one of the most widespread fish skin bacterial pathogens, Flavobacterium columnare (F. columnare). To gain insight into the pathogenesis and progression of the infection in skin, a recombinant F. columnare expressing green fluorescent protein (GFP) was constructed and showed to successfully invade the skin mucosa. This pathogen induced strong skin innate immune and inflammatory responses at the initial phases of infection. More critically, we found that the skin mucus of fish having survived the infection contained significant IgT- but not IgM- or IgD-specific titers against the bacteria. Moreover, we demonstrate the local proliferation and production of IgT+ B-cells and pathogen-specific IgT titers respectively within the SALT upon bacterial infection. Thus, our findings represent the first demonstration that IgT is the main Ig isotype induced by the skin mucosa upon bacterial infection, and that because of the large surface of the skin, its SALT probably represents a prominent IgT inductive site in fish. Author summary In contrast to mammalian skin, that of teleost fish is the largest mucosal surface containing a skin-associated lymphoid tissue (SALT). Thus far, IgT representing the prevalent immunoglobulin (Ig) in SALT have only been reported upon infection with a parasite. However, very little is known about the types of B cells and Igs responding to bacterial infection in the teleost skin mucosa, as well as the inductive or effector role of the SALT in such responses. To address these questions, we infected rainbow trout (Oncorhynchus mykiss) with F. columnare an important skin pathogen that causes significant losses both in wild and farmed fish populations. Remarkably, strong pathogen-specific IgT responses and accumulation of IgT+ B cells were induced in the cutaneous mucus and skin epidermis respectively upon infection. Evidence for the skin being an IgT inductive site was shown by the finding of local IgT+ B cells proliferation and pathogen-specific IgT tites in cultured trout skin explants. Thus, our findings demonstrate that IgT is the prevailing Ig isotype induced by the skin mucosa upon bacterial infection, and that the skin represents an IgT inductive site in fish.

Density-functional method PW91 has been selected to investigate the structural, electronic and magnetic properties of Au4M (M =Sc–Zn) clusters. Geometry optimisations show that the M atoms in the ground-state Au4M clusters favour the most highly coordinated position. The ground-state Au4M clusters possess a solid structure for M = Sc and Ti and a planar structure for M = V–Zn. The characteristic frequency of the doped clusters is much greater than that of pure gold cluster. The relative stability and chemical activity are analysed by means of the averaged binding energy and highest occupied molecular orbital and lowest unoccupied molecular orbital energy gap for the lowest energy Au4M clusters. It is found that the dopant atoms can enhance the thermal stability of the host cluster except for Zn atom. The Au4Ti, Au4Mn and Au4Zn clusters have relatively higher chemical stability. The vertical detachment energy, electron affinity and photoelectron spectrum are calculated and simulated theoretically for all t...