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Natural Inhabitant (natural + inhabitant)
Selected AbstractsThe association between non-biting midges and Vibrio choleraeENVIRONMENTAL MICROBIOLOGY, Issue 12 2008Meir Broza Summary Vibrio cholerae is a natural inhabitant of aquatic ecosystems, yet its interactions within this habitat are poorly understood. Here we describe the current knowledge on the interaction of V. cholerae with one group of co-inhabitants, the chironomids. Chironomids, non-biting midges (Chironomidae, Diptera), are an abundant macroinvertebrate group encountered in freshwater aquatic habitats. As holometabolous insects, chironomids start life when their larvae hatch from eggs laid at the water/air interface; through various feeding strategies, the larvae grow and pupate to become short-lived, non-feeding, adult flying insects. The discovery of the connection between V. cholerae and chironomids was accidental. While working with Chironomus transavaalensis, we observed the disintegration of its egg masses and searched for a possible microbial agent. We identified V. cholerae as the primary cause of this phenomenon. Haemagglutinin/protease, a secreted extracellular enzyme, degraded the gelatinous matrix surrounding the eggs, enabling bacterial growth. Observation of chironomids in relation to V. cholerae continuously for 7 years in various types of water bodies in Israel, India, and Africa revealed that environmental V. cholerae adhere to egg-mass surfaces of various Chironomini (,bloodworms'). The flying adults' potential to serve as mechanical vectors of V. cholerae from one water body to another was established. This, in turn, suggested that these insects play a role in the ecology of V. cholerae and possibly take part in the dissemination of the pathogenic serogroups during, and especially between, epidemics. [source] Dependent population dynamics between chironomids (nonbiting midges) and Vibrio choleraeFEMS MICROBIOLOGY ECOLOGY, Issue 1 2006Malka Halpern Abstract Vibrio cholerae, the causative agent of cholera, is a natural inhabitant of the aquatic ecosystem. Chironomid (nonbiting midges) egg masses were recently found to harbour V. cholerae non-O1 and non-O139, providing a natural reservoir for the cholera bacterium. Chironomid populations and the presence of V. cholerae in chironomid egg masses were monitored. All V. cholerae isolates were able to degrade chironomid egg masses. The following virulence associated genes were detected in the bacterial isolates: hapA (100%), toxR (100%), hlyA (72%) and ompU (28%). The chironomid populations and the V. cholerae in their egg masses followed the phenological succession and interaction of host,pathogen population dynamics. A peak in the chironomid population was followed by a peak in the V. cholerae population. If such a connection is further substantiated for the pathogenic serogroups of V. cholerae in endemic areas of the disease, it may lead to a better understanding of the role of chironomids as a host for the cholera bacterium. [source] Histological and immunocytochemical localization of serotonin-like immunoreactivity in the brain and optic ganglia of the Indian white shrimp, Fenneropenaeus indicusMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2008S. Santhoshi Abstract Serotonin is one of the important neurotransmitter and neuromodulator so far studied in crustacean models. With its secretory sites well-studied in higher crustaceans, its function in controlling the release of metabolic hormones from their storage and release sites has been well proved. The present study attempts to localize serotonin-like immunoreactivity in Fenneropenaeus indicus, a commercially important shrimp species and a natural inhabitant of the Indian oceans. Histological studies were employed to visualize the different types of neurosecretory cells and their regions of occurrence in brain and optic ganglia on the basis of their size, shape, and tinctorial properties. Immunocytochemical studies were performed in the brain and optic ganglia with specific antisera against serotonin in combination with peroxidase anti-peroxidase to map the serotonin-like immunoreactive cells. Variations in the immunoreactivity were observed on comparing the cells of brain and optic ganglia. Medulla terminalis region had intense serotonin immunoreactivity suggesting it to be the primary source of the neurotransmitter. Microsc. Res. Tech., 2008. © 2007 Wiley-Liss, Inc. [source] Surrounded by mycobacteria: nontuberculous mycobacteria in the human environmentJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2009J.O. Falkinham Summary A majority of the Mycobacterium species, called the nontuberculous mycobacteria (NTM), are natural inhabitants of natural waters, engineered water systems, and soils. As a consequence of their ubiquitous distribution, humans are surrounded by these opportunistic pathogens. A cardinal feature of mycobacterial cells is the presence of a hydrophobic, lipid-rich outer membrane. The hydrophobicity of NTM is a major determinant of aerosolization, surface adherence, biofilm-formation, and disinfectant- and antibiotic resistance. The NTM are oligotrophs, able to grow at low carbon levels [>50 ,g assimilable organic carbon (AOC) l,1], making them effective competitors in low nutrient, and disinfected environments (drinking water). Biofilm formation and oligotrophy lead to survival, persistence, and growth in drinking water distribution systems. In addition to their role as human and animal pathogens, the widespread distribution of NTM in the environment, coupled with their ability to degrade and metabolize a variety of complex hydrocarbons including pollutants, suggests that NTM may be agents of nutrient cycling. [source] | ||||||||||