Colonization natural selection

Colonization is a long process that usually starts by a founder event and is followed by a series of population expansions and new foundations. It would be unrealistic to assert that natural selection... 

After a certain period of time, a natural selection process will yield strains which overcome the biocidal effect. In the case of copper, the first colonizers will be organisms tolerant to copper and may be later, in turn, colonized by copper-sensitive organisms. 

The use of liposomes as boron delivery vehicles for BNCT has been extensively studied, since liposomes can transport large amounts of boronated molecules, both hydrophobic and hydrophilic in nature, selectively into tumor cells. Three methods for incorporation of boron into liposomes have been reported incorporation of hydrophobic molecules into lipid bilayers, entrapment of hydrophilic molecules into the liposomes aqueous core, and the use of boronated lipids. Recently, PEG-based liposomes (DPPC/cholesterol/DSPC-PEG2000) have been used as effective carriers of boronated compounds within tumor tissues. Intraveuously injected B-PEG-liposomes on human pancreatic carcinoma xenografts in nude mice inhibited tumor growth after thermal neutron irradiation. The cationic liposome formulation (DOTAP/DOPC/DOPE) was used to deliver ortho-carboranyl P-lactoside (LCOB) aud l-methyl-ort/j< -carboranyl-2-hexylthioporphyrazine (H2PZ-COB) within DHD/K12/TRb (DHD) rat colon carcinoma and B16-F10 murine melanoma cell lines. Results from these studies show that a thirty-fold increase on the cellular uptake of B was obtained for the boronated compounds in the liposome formulation as compared with that of the BPA-fructose complex. 

Recently, Barrero et al. [20] have tested the activity of natural podolactones LL-Z1271a (63) and 68, and of synthetic derivatives 94-99, the latter being a mixture of isomers, against four tumoral cell lines P-388, A-549 (human lung carcinome), HT-29 (human colon carcinome) and MEL-28 (human melanome) (Table 2). The two natural compounds, as well as 98 showed a potent activity (ICso[Pg.470]

---