Synchronisation of the GHRH network might be facultative for factors, like ghrelin, which enhance the amplitude and not the frequency of GH pulses [1].
According to the findings in this work, the symbiosis may be facultative for some Symbiodinium spp. because they can find some of the benefits that they obtain from the coral in other habitats such as macroalgal beds.
Alternatively, these proteins may have been secondarily lost in several species, indicating that MAM proteins may be facultative for pathway function or replaceable by other proteins.
Some symbionts, particularly some that are facultative for hosts, are more recently derived compared with ancient nutritional symbionts (Buchner 1965), and despite being related to pathogens, have conditionally beneficial effects upon their hosts (reviewed in Oliver et al. 2010).
Maternally transmitted symbionts that are facultative for hosts are often referred to as "secondary" symbionts and include several species of Enterobacteriaceae that infect aphids (Oliver et al. 2010), Arsenophonus species in many insects (Wilkes et al. 2009), Wolbachia species (Wu et al. 2004; Klasson et al. 2009), and others.
Oral therapy was a requirement for inclusion, whereas additional therapy with inhaled iloprost was facultative.
The strain was facultative anaerobic.
However, Fnip1 and conditional Flcn mutants show similar defects in B cell development (Baba et al., 2012), indicating that requirement for Fnip2 is facultative and cell type dependent.
In addition to their capacity for extracellular survival, Salmonellae are facultative intracellular bacteria and their ability to survive within cells is essential for virulence [14].
For example, Myxobacteria are facultative predators.
