Three-dimensional interactions between enhancers and promoters during intestinal differentiation depend upon HNF4

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Clockwise and counterclockwise hysteresis characterize state changes in the same aquatic ecosystem

Incremental increases in a driver variable, such as nutrients or detritus, can trigger abrupt shifts in aquatic ecosystems that may exhibit hysteretic dynamics and a slow return to the initial state. A model system for understanding these dynamics is the microbial assemblage that inhabits the cup‐shaped leaves of the pitcher plant Sarracenia purpurea. With enrichment of organic matter, this system flips within three days from an oxygen‐rich state to an oxygen‐poor state. In a replicated greenhouse experiment, we enriched pitcher‐plant leaves at different rates with bovine serum albumin (BSA), a molecular substitute for detritus. Changes in dissolved oxygen (DO) and undigested BSA concentration were monitored during enrichment and recovery phases. With increasing enrichment rates, the dynamics ranged from clockwise hysteresis (low), to environmental tracking (medium), to novel counter‐clockwise hysteresis (high). These experiments demonstrate that detrital enrichment rate can modulate a diversity of hysteretic responses within a single aquatic ecosystem, and suggest different management strategies may be needed to mitigate the effects of high vs. low rates of detrital enrichment.     

Ecology and ovarian function among Lese women of the Ituri Forest, Zaire

Ovarian function is examined in 35 Lese women inhabiting the Ituri Forest of northeastern Zaire over a period of 4 months through measurements of progesterone in saliva samples collected twice weekly. Ovulatory frequency is found to be only 56% on average, with a pattern of age variation similar to that observed in western women, though lower in level at each age. Average luteal progesterone levels of the Lese women are lower than those of Boston controls even if only ovulatory cycles are considered. Women with the poorest nutritional status, inferred from longitudinal weight changes and weight for height, show the greatest compromise of ovarian function, and the average ovulatory frequency of the whole sample declines in parallel with a period of weight loss over four months. It is suggested that low ovulatory frequency and luteal insufficiency contribute to the low fecundity of the Lese population and that nutritional status is likely to be one of the ecological factors modulating this effect.     

Menstrual variation in salivary testosterone among regularly cycling women.

To determine menstrual variation in salivary testosterone daily saliva samples were collected from 20 regularly cycling women. Results indicate that the menstrual profile of salivary testosterone for both ovulatory and anovulatory cycles exhibits local peaks during the follicular phase and at midcycle, as well as a luteal trough. However, the testosterone profile for anovulatory cycles exhibited a later midcycle peak than that for ovulatory cycles, as well as significantly higher average testosterone levels. These results extend the observation of a midcycle peak in serum testosterone to saliva and suggest the existence of a follicular peak in unbound testosterone coincident with the early androgen production of a cohort of developing follicles.     

Age determination using the apodeme structure in adult screwworm flies (Cochliomyia hominivorax)

A method of age determination of adult screwworm flies is described and documented. This method uses the diurnal differences in the deposition of apodeme layers as a basis for counting the age in days since eclosion. The method is accurate to plus or minus one day, and can be determined on meterial that has been dried, pinned, frozen, or preserved in ethanol or other fixatives.     

Effects of light and turbidity on feeding,growth, and survival of larval Delta Smelt (Hypomesus transpacificus,Actinopterygii, Osmeridae)

Hydrobiologia - Understanding how environmental factors—here, light intensity and turbidity—influence the feeding, growth, and survival of larval Delta Smelt is critical for optimizing...