Nutrient-rich environment

This profile becomes relevant as agricultural lands are converted. Because A Horizon soils from productive farms are valuable and nutrient-rich, land buyers usually treat them as a mineable resource for resale. Prior to construction, therefore, tractors and land moving equipment scrape the many tons of valuable soil off the surface and cart it away (consider a 100 square yard site scraped to the depth of just a few feet will produce around ten tons of soil at retail, 40-pound bags sell for 6 each). This leaves a far thinner layer of good soil near the surface. Even where intentional removal of topsoil is not conducted, construction typically leads to large-scale erosion of this valuable topsoil layer that, coupled with compaction from heavy equipment and machinery, later makes for a poor growing environment. ... 

The cestodes are a large and diverse group of platyhelminths that share two common features as adults, they have an elongate body and they lack an alimentary canal. Consequently, they must reside in an elongate, nutrient-rich environment. Thus, adult tapeworms are almost invariably found in the definitive hosts intestine where they absorb nutrients directly across their tegument. The cestode life cycle, with the notable exception of Hymenolepis nana (Fig. 9.1), is indirect and involves at least one intermediate host. Unlike adult tapeworms, the juvenile forms are morphologically quite diverse and can be found in almost... 

Carrion itself forms a lucrative substrate for invertebrate colonization however, in outdoor situations the interface between this substrate and the underlying soil, and the soil itself, also form attractive environments for certain organisms. The seepage of nutrient-rich fluids into the soil beneath the corpse significantly alters the microenvironment, affecting the inhabitant fauna. The arthropod assemblage may thus be considered to be affected by and reflective of the decomposition of the corpse and may therefore have some potential in contribution to forensic investigation (Bornemissza 1957). 

The high bioavailability of Cd in the marine environment from Terra Nova Bay was ascribed to upwelling of deep nutrient rich water nearshore (70). Cadmiun has a nutrient-like concentration gradient in the water column, lower close to the surface and increasing with depth (75). In the water column, Cd would be absorbed by the phytoplankton, during the summer bloom, thus becoming available for benthic molluscs in which the Cd is bioaccumulated. Ecological studies undertaken in the inner and outer part of Potter Cove showed that after seasonal ice retreat no phytoplankton bloom occured (35). In spite of the low planktonic production, rich benthic animal comunities are found in the area (29). 

Its numerous pits and channels provide an enormous surface area for absorption, and the tegument is constantly exposed to a nutrient-rich environment. Many enzymes that function in amino acid absorption are located in the tegument, and some of these, such as leucine aminopeptidase, are not present in the gut. Trematodes possess an incomplete digestive tract, and both S. mansoni and F. hepatica can survive extended in vitro incubations in the absence of detectable nutrient absorption across the intestine (63,64). Glucose absorption in trematodes can be detected during immature stages of the life cycle, which lack an intestine (65). 

Nutrient release into the environment is rapid in nutrient-rich wetlands (eutrophic wetlands) where nutrient supply meets the needs of microbial growth. Nitrogen and phosphorus release is directly related to the decomposition end products methane and carbon dioxide (Figure 5.65). In contrast, nutrients may be held tightly within the microbial biomass component of low-nutrient wetlands. 

Lonisiana s coastal environment, particularly the sediment-water systems, provides a wide range of microhabitats for microbial activity. Sediments range from saline to fresh, well oxidized to strongly reduced, and nutrient poor to nutrient rich. Oxygen availability, pH, temperature, salinity, and nutrient status are a few parameters, which can vary considerably within a coastal sediment system. 

Comment. There appear evidences that in the so called malignant transformation of somatic or stem cells in multicellular hosts, reversion takes place to an ancient life style of the cell. Trypanosoma can conceal its smface antigens, as transformed cells in a multicellular host also refrain from antigenic expression by withholding their histocompatibility complexes. In a nutrient rich environment. Trypanosoma cells replicate and maintain their telomere lengths after each cell divisions (especially when replicating in liquid media). 

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