Evidence against the energetic cost hypothesis for the short introns in highly expressed genes

Table 1 Tissue/organ samples and the number of specific genes analyzed in this study^a

	Large tissue/organ (number of specific genes; tissue/organ weight)^b	Small tissue/organ (number of specific genes; tissue/organ weight)^b
Homo sapiens	Cultured adipocytes (18; 9 Kg)	Brain amygdala (22; --)
	Liver (79; 1.5 Kg)	Hypothalamus (7; 4 g)
	Lung (18; 1 Kg)	Pituitary (6; 5 g)
	Skeletal muscle (4; 27 Kg)	Tonsil (1; 30–40 g)
	Skin (6; 5 Kg)	Prostate (13; 20 g)
	Smooth muscle (24; --)	Thymus (11; 30–40 g)
		Thyroid (25; 18–60 g)
		Tongue (11; 70 g)
Mus musculus	Adipose tissue (13; --)	Amygdala (4; --)
	Liver (76; 2 g)	Hypothalamus (12; < 60 mg)
	Skeletal muscle (47; --)	Pituitary (29; 3 mg)
	Epidermis (4; --)	Trigeminal (7; --)
		Prostate (24; 0.11 g)
		Thymus (64; < 60 mg)
		Thyroid (21; 15 mg)
		Tongue epidermis (14; --)
		Retina (71; --)

^aSee Additional File 1 and Additional File 2 for full lists of these genes.
^b Some samples, like the subthalamic nucleus and trigeminal ganglion, are undoubtedly small tissues/organs. These may be not included in this study because we could not find any specific genes for them. The tissue/organ weights were obtained directly from literatures and internet resources (for example, Wikipedia, the free encyclopedia) or calculated according to their ratio to body by assuming that the weights of adult human and mouse bodies are about 70 Kg and 30 g, respectively (when different sources of data are not consistent, we retained the conservative estimation) [16–24, 34]. Some samples (like smooth muscle, tongue epidermis and retina) were categorized into large tissue/organs or small tissue/organs on the basis of experience. Some mouse tissue/organs were categorized by consulting their human homologs. In humans, the lower limit of large tissue/organ samples was lung (about 1000 g), while the upper limit of small tissue/organ samples was tongue (70 g). In mice, the lower limit of large tissue/organ samples was liver (about 2 g), while the upper limit of small tissue/organ samples was prostate (0.11 g).

ISSN: 2730-7182