Continued studies of the relationship of specific gravity to total solids of potatoes

The reliability of specific gravity as a measure of total solids was studied statistically. Studies on an expanded number of currently popular American potato samples indicated that differences were great enough that the accepted Von Scheele regression curve now borders on the obsolete. Variations in the relationship caused by lack of uniformity in analytical techniques, as well as inherent variations in the potatoes themselves indicated that a linear regression curve based on American potato varieties is sorely needed. It is suggested that such a curve be obtained through cooperative effort sponsored by the American Potato Association.     

Amey: A multipurpose, russet-skinned potato cultivar for the Eastern United States

Amey is a late-maturing, russet-skinned, whitefleshed potato cultivar that yields more than Russet Burbank in most eastern United States potato production areas. Tubers of Amey are mostly oblong, occasionally long, with an evenly russetted skin. Tubers of Amey are smoother, more attractive, and have a much lower incidence of external defects than Russet Burbank. The specific gravity of Amey is equal to or greater than the specific gravity of Russet Burbank. French fries produced from Amey are lighter than or equal in color to those produced from Russet Burbank; however, tubers are frequently not long enough to satisfy the french fry industry. Baking and taste quality of Amey are excellent, and it has potential as a fresh market potato. Amey is resistant to race Rol of the golden nematode, powdery scab, and common scab. It is moderately susceptible to Verticillium wilt. It is susceptible to potato leafroll virus, late blight, and early blight.     

Marcy: A chipping variety with resistance to common scab and the golden nematode

‘Marcy’ is a white-skinned, white-fleshed potato cultivar notable for its high yield, good chip color, and resistance to common scab and race Ro1 of the golden cyst nematode. It was selected from a cross made at Cornell University in 1990 between ‘Atlantic’ and Q155-3. Full-season marketable yields of Marcy have averaged 15% to 20% greater than Atlantic in 83 trials across New York, Maine, and Pennsylvania. Specific gravity of Marcy has averaged 0.008 less than Atlantic. Chip color out of 7 C storage in New York has been similar to ‘Pike’, but not as light as ‘Snowden’. Marcy tubers have an attractive oval shape, shallow eyes, and highly textured skin. Marcy was jointly released by the New York and Pennsylvania Agricultural Experiment Stations in 2002.     

Somerset: A new chipping potato variety

The Somerset potato variety is a medium-maturing variety with attractive, round to oblong, white-skinned, white-fleshed tubers with shallow eyes. Its major use is expected to be as a chipping variety in areas where potatoes are stored for some length of time, since its sugar content is lower than most varieties during storage, and it can be chipped after six months in storage. Somerset does not show the net necrosis caused by potato leafroll virus, and is immune to race 0 of Phytophthora infestans (late blight). Somerset is also moderately resistant to infection by Alternaria solani (early blight), and is only moderately susceptible to Verticillium wilt. Somerset is more susceptible to both common and acid scab than Superior, but less susceptible than Kennebec and Katahdin. It also has shown susceptibility to skinning and shatter bruise, but does not have a strong blackspot bruise reaction.     

Somatotropin response in vitro to corticosterone and triiodothyronine during chick embryonic development: Involvement of type I and type II glucocorticoid receptors

Corticosterone (CORT) can stimulate growth hormone (GH) secretion on embryonic day (e) 12 in the chicken. However, CORT failed to induce GH secretion on e20 in a single report, suggesting that regulation of GH production changes during embryonic development. Secretion in response to CORT during embryonic development is modulated by the thyroid hormones triiodothyronine (T₃) and thyroxine (T₄). Growth hormone responses on e12 involve both glucocorticoid (GR) and mineralocorticoid receptors (MR); however, involvement of MR has not been evaluated past e12. To further define changes in somatotroph responsiveness to CORT, pituitary cells obtained on e12–e20 were cultured with CORT alone and in combination with T₃ and GH-releasing hormone (GHRH). Growth hormone mRNA levels and protein secretion were quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and radioimmunoassay (RIA), respectively. Corticosterone significantly increased GH mRNA and protein secretion on e12; however, mRNA concentration and protein secretion were unaffected on e20. Contributions of GR and MR in CORT responses were evaluated using GR and MR antagonists. Treatment with a GR-specific antagonist effectively blocked the CORT-induced increase in GH secretion on e12. The same treatment on e20 had no effect on GH secretion. These findings demonstrate that GR is directly involved in glucocorticoid stimulation of GH secretion at the time of somatotroph differentiation but is not regulatory at the end of embryonic development. We conclude that positive somatotroph responses to CORT are lost during chicken embryonic development and that GR is the primary regulator of CORT-induced GH secretion.