Horizontal transmissions

Fig. 3.9 Schematic view of a Mbssbauer cryostat with a superconducting cryo-magnet for horizontal transmission experiments with the field parallel to the y-rays. Without a magnet the helium reservoir may end above the optical axis, such that the cryostat can have a narrow tail with much shorter window-to-window distance...

Comparison of host and symbiont phylogenies is a powerful method for assessing the occurrence and frequency of horizontal transmission (Moran and Baumann, 1994). There are limited sequence data available for assessing the phylogeny of filarial nematodes. Comparison of Wolbachia... 

The usefulness of the Mueller formulation becomes apparent when we realize that Mueller matrices give us a simple means of determining the state of polarization of a beam transmitted by an optical element for an arbitrarily polarized incident beam. Moreover, if a series of optical elements is interposed in a beam, the combined effect of all these elements may be determined by merely multif ying their associated Mueller matrices. As an example, let us consider how a circular polarizer can be constructed by superposing a linear polarizer and a hnear retarder. The beam is first incident on a linear polarizer with horizontal transmission axis ( = 0°), the Mueller matrix for which is obtained from (2.87) ... 

Few have attempted to isolate and cultivate these consortia, and to the best of our knowledge only T. Villareal (1989) was successful for several months in culturing a Rhizosolenia-Richelia symbiosis. The division cycles of the host Rhizosolenia and Richelia were asynchronous in culture, and as such several asymbiotic hosts were observed (Villareal, 1989). Transmission from host to daughter cell is typically vertical, however asymbiotic hosts and free-living Richelia observed in the field and culture suggest horizontal transmission as well. 

Campylobacter infection. It has been shown that water is an important route of horizontal transmission on broiler farms (Chaveerach et al., 2002). 

The vast majority of infants bom to HBeAg positive mothers become infected, and most become chronic carriers if not vaccinated, as mentioned by Hsieh et al. (1992). The risk of horizontal transmission of HBV is especially important during elementary school years between the ages of 7 and 11 years according to a survey carried out on 1,500 school children by Degertekin et al. (2000). 

Prevalence of CWD in captive and wild herds is remarkably high and efficient horizontal transmission is driving it to epidemic proportions. 

There are many ways in which CWD prions could reach the soil and remain there. One possible route of soil contamination could be from decomposition of cervids infected with CWD. Though deer do not consume carcasses, they do forage on foliage that grows in abundance around the decomposition site [33], Prolonged exposure to fecal matter could also indicate efficient horizontal transmission. 

The above-mentioned routes of CWD prion contamination in soil could also lead to contamination of water due to rainfall and snow-melt run off into water sources. Due to the large number of cervids infected with CWD in the Northern Colorado area, sPMCA revealed the presence of protease resistant prion protein in the water, albeit in very low doses which could not cause infection. The authors suggest that prions could accumulate in environmental sources and could potentially promote CWD transmission [42]. Overall, it appears reasonable that environmental CWD prions may significantly contribute to horizontal transmission. 

Brem D, Leuchtmann A. High prevalence of horizontal transmission of the fungal endophyte Epichloe sylvatica. Bull Geohot Inst ETH 65 3-12, 1999. 

Chung K-R, Schardl CL. Sexual cycle and horizontal transmission of the grass symbiont, Epichloe typhina. Mycol Res 101 295-301, 1997. 

The Bio-Path Cockroach Control Chamber (EcoScience, USA) is promoted for its ecological or green credentials, using nature to control nature s pests (Andis, 1994). In essence, it employs a bait technique to lure cockroaches inside, and the chamber design ensures that, as they leave, they are inoculated with dry conidia of M. anisopliae. Horizontal transmission within the insect populations is an integral component of this strategy (Kaakeh et al., 1996). 

Kaakeh W, Reid BL, Bennett GM. Horizontal transmission of the entomopathogenic fungus Metarhizium anisopliae (Imperfect Fungi Hyphomycetes) and hydromethyl-non among German cockroaches (Dictyoptera Blatellidae). J Entomol Sci 31 318-390, 1996. 

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