The effects of environmental factors are often seen in gene expression changes, as predominantly down-regulation of all gene programs for sensitive genotypes or in the case of tolerant genotypes as up-regulation of protective mechanisms [ 23, 28]. Figure 3 shows the phenotype of flowers, anthers and pollen viability of HS1 and FR grown under control conditions and two weeks of MHS.
From a sabermetric standpoint, this kind of human element is often seen as a confounding factor, a messy variable that cannot be accounted for (and often does not need to be).
But if the truth be told, in an age where religion is often seen as a dividing factor as opposed to a uniting one, I prefer to not describe myself in religious terms at all.
A second factor, often seen in the genus Gagea, is partial or full sterility caused by high (and especially odd) ploidy levels.
P53 is a transcription factor that is often seen as an important pro-apoptotic factor because DNA-injury-increased P53 induces the expression of Bax and promotes the release of cytochrome C [ 27, 28].
For all that the precautionary principle is often seen as a limiting factor, it can be a poke to think about our choices.
The concentration of lignin, its composition and the manner in which it binds holocellulose within the cell-wall matrix is often seen as an exacerbating factor of cell-wall recalcitrance to enzymatic deconstruction (Vanholme et al., 2010; Hodgson et al., 2011; Ding et al., 2012).
Viral infections are often seen as precipitating factors (see Table 2).
Increased expression of cyclin D1, COX-2, MMP-9 and several inhibitors of apoptosis proteins (including survivin and IAP1) is often seen with nuclear factor-κB stimulus.
Although B7 molecules are often seen as crucial factors for costimulation, some reports have also indicated that other costimulatory molecules, for example, ICAM-1, may be sufficient for efficient T-cell activation (Robinson and Delvig, 2002).
However, smoking is often seen as a risk factor that is not easily altered, although several studies suggest otherwise [ 5].
