Experimental Analysis of Metabolic Adaptation of Cottus Carolinae in Response to Photoperiod and Food Availability

Epigean (surface) and hypogean (cave) habitats differ significantly, thereby influencing organisms that inhabit these environments in varying ways. As organisms move from surface to cave environments, they. adapt to cave conditions: constant darkness, relatively constant temperatures year-round, low food availability, and high humidity. Fish adjusted to cave life often experience reductions in pigmentation, eye size, and metabolic rate. Metabolism is, in general, influenced by temperature, seasonal• • changes, photoperiod, and food availability. The objective of this research was to understand the alteration of metabolic rate in laboratory acclimated Cottus carolinae (banded sculpin) in response to photoperiod and food availability. Metabolic rates of C. carolinae were measured after acclimation to laboratory aquaria. After initial metabolic measurement, C. carolinae were placed into one of four treatments: 1) 24-hours dark, low food availability, 2) 24-hours dark, high food availability, 3) 12-hours light: 12-hours dark, low food availability, and 4) 12-hours light: 12-hours dark, high food availability. After eight weeks of acclimation to experimental treatments, metabolic rates of fish were measured following the same protocol used in initial measurements. Results indicated no statistically significant differences existed in C. carolinae as a result of photoperiod, food availability, or the interaction ofthe two. Also, no significant differences existed between laboratory and field measurements from cave and surface environments. However, many variables were identified that may have influenced fish metabolism in the laboratory. Further study is needed to determine influences of photoperiod and food availability on metabolism of C. carolinae

Screening ethnically diverse human embryonic stem cells identifies a chromosome 20 minimal amplicon conferring growth advantage

The International Stem Cell Initiative analyzed 125 human embryonic stem (ES) cell lines and 11 induced pluripotent stem (iPS) cell lines, from 38 laboratories worldwide, for genetic changes occurring during culture. Most lines were analyzed at an early and late passage. Single-nucleotide polymorphism (SNP) analysis revealed that they included representatives of most major ethnic groups. Most lines remained karyotypically normal, but there was a progressive tendency to acquire changes on prolonged culture, commonly affecting chromosomes 1, 12, 17 and 20. DNA methylation patterns changed haphazardly with no link to time in culture. Structural variants, determined from the SNP arrays, also appeared sporadically. No common variants related to culture were observed on chromosomes 1, 12 and 17, but a minimal amplicon in chromosome 20q11.21, including three genes expressed in human ES cells, ID1, BCL2L1 and HM13, occurred in >20% of the lines. Of these genes, BCL2L1 is a strong candidate for driving culture adaptation of ES cells