Experimental reproduction of White Feces Syndrome in whiteleg shrimp, Penaeus vannamei

White Feces Syndrome (WFS) is an emergent disease of penaeid shrimp (Penaeus monodon and P. vannamei) that is identified by the presence of floating white fecal strings on pond water in grow-out ponds. Although the clinical manifestations of WFS are well defined, the underling etiology remains obscure. WFS has been associated with several enteric pathogens, including Enterocytozoon hepatopenaei (EHP). The association is based on studies that found areas where WFS has been reported, the prevalence and severity of EHP infection are high. In this study, we describe an experimental reproduction of WFS in P. vannamei pre-infected with EHP and challenged with a unique isolate of Vibrio parahaemolyticus isolated from the gastrointestinal tract of a shrimp displaying WFS. Upon laboratory challenge, shrimp displaying white fecal strings and white discoloration of the gastrointestinal tract were analyzed by histopathology, in-situ hybridization and quantitative PCR. Histological analysis confirmed the lesions of EHP and septic hepatopancreatic necrosis in the hepatopancreas of shrimp exposed to both pathogens. Quantitative PCR showed shrimp infected with both EHP and V. parahaemolyticus had a significantly higher load of EHP compared to shrimp infected with EHP alone. This is the first demonstration of experimental reproduction of WFS under laboratory conditions when animals are infected with EHP and V. parahaemolyticus concurrently. The data revealed a synergistic relation between EHP and V. parahaemolyticus isolate that led to the manifestation of WFS. We propose the gross signs of WFS can be used as an indicator of the presence of EHP infection in association with a particular strain of an enteric Vibrio spp. in countries where EHP is endemic.

Pathomorphological Changes in Organs of Rabbits with Experimental Colibacillosis

The aim of this research was to study pathomorphological alterations in the internal organs of rabbits through experimental reproduction of colibacillosis. The studies were conducted on 10 clinically healthy rabbits at the age of 3 months from a private farm. Animals were infected by intraperitoneal injection of a suspension of a pure culture of Escherichia coli isolated from a sand lizard. The disease of infected rabbits was accompanied by cachexia, dehydration and fever. The pathological process in the organism of infected animals was characterized by the violation of hemodynamics, the protein dystrophy of the parenchyma of liver, kidneys, myocardium and the formation of specific granulomas in the lungs and liver. The edema of reticular tissue and the hyperplasia of lymph nodes were observed in the organs of the immune system. The expressive edema of mucous membrane and submucosa, as well as alterative and necrotic processes were detected in the intestine.

Pathomorphology of certain organs of immunogenesis by experimental reproduction of coronavirus infection in dogs

The article, based on the results of histological studies, presents data on the microscopic structure of the immune system – thymus, spleen, lymph nodes of dogs with experimental infection with coronavirus enteritis. Pathomorphological studies of immunocompetent organs from the dead (n = 5) puppies crossed Labrador breeds with outbred, infected with a coronavirus field isolate cultured on heterologous cell cultures (kidney kidney hamster (BHK-21), rabbit kidney (RK-13) and the renal mumps (SPEV). Pathological dissection of dogs was performed by partial evisceration in the usual sequence. Prepared histological sections were stained with hematoxylin and eosin according to standard recipes. The general histological structure and microstructural changes of histo- and cytostructures of organs in histological samples were studied under a light microscope. During coronavirus enteritis in dogs, pathomorphological changes in immunocompetent organs were found, which characterize the suppression of immunogenesis function during an infectious disease of viral etiology. Thus, in the spleen there are spotted hemorrhages, lymph nodes, moderate hyperplasia, with signs of hemorrhagic inflammation. Active proliferation of lymphoid cells, which leads to hyperplasia, is one of the markers of the pathogen's effect on the macroorganism in the form of an inflammatory process in regional lymph nodes, which indicates the multiplication of the virus and the development of immunological processes. Based on our analysis of literature sources, monitoring results and our own research, it was found that viral enteritis occupies a leading place in the infectious pathology of dogs and causes significant harm to animal owners. Thus, the need for additional research to clarify, supplement and summarize data on the pathomorphology of various organs and tissues in canine corona viridae enteritis, current immunoprophylaxis and treatment can significantly reduce the incidence and mortality from infection. We found a set of histological changes in the immune system during the experimental reproduction of coronavirus infection, can be considered a characteristic criterion for pathomorphological differential diagnosis of coronavirus enteritis in dogs.

Spatial and temporal dynamics of Belousov-Zhabotinsky reaction: A STEM approach

An integrative methodology for teaching science is proposed through the STEM methodology (Science-Technology-EngineeringMathematics).The STEM methodology provides students the opportunity to combine knowledge in an interdisciplinary and collaborative manner, allowing the development of creative and systemic thinking. As a model we propose the experimental reproduction of the Belousov-Zhabotinsky reaction (BZ), which is the standard prototype of non-linear chemistry, in addition we used the Python V2.7 programming software and the Jupyter platform for the computational reproduction of the BZ reaction. The STEM methodology could help the development of new competences for students, that is, it will provide them with tools to solve complex current problems that require of the interdisciplinarity