The role of estrogen receptor α in the regulation of bone and growth plate cartilage

Estrogens are important endocrine regulators of skeletal growth and maintenance in both females and males. Studies have demonstrated that the estrogen receptor (ER)-α is the main mediator of these estrogenic effects in bone. Therefore, estrogen signaling via ERα is a target both for affecting longitudinal bone growth and bone remodeling. However, treatment with estradiol (E2) leads to an increased risk of side effects such as venous thromboembolism and breast cancer. Thus, an improved understanding of the signaling pathways of ERα will be essential in order to find better bone specific treatments with minimal adverse effects for different estrogen-related bone disorders. This review summarizes the recent data regarding the intracellular signaling mechanisms, in vivo, mediated by the ERα activation functions (AFs), AF-1 and AF-2, and the effect on bone, growth plate and other estrogen responsive tissues. In addition, we review the recent cell-specific ERα-deleted mouse models lacking ERα specifically in neuronal cells or growth plate cartilage. The newly characterized signaling pathways of estrogen, described in this review, provide a better understanding of the ERα signaling pathways, which may facilitate the design of new, bone-specific treatment strategies with minimal adverse effects.     

Stoneflies (Plecoptera) of Mount Rainier National Park, Washington

Mount Rainier National Park, with an area of 95,356 ha, is approximately one-third as large as the state of Rhode Island. The lowest point is 490 m in elevation in the southeastern corner near where the Ohanapecosh River crosses the southern boundary. Columbia Crest is the highest point at 4392 m. The entire park is a rugged landscape marked by the major topographical feature, Mount Rainier, comprising over 25,899 ha, almost one-third of the park. The park lies entirely west of the crest line of the Cascade Range. Most streams in the park originate on Mount Rainier; however, several large rivers meander through the park near its boundaries. One of the first attempts to summarize the stoneflies of Washington, including Mount Rainier National Park, was Hoppe's 1938 work that reported ca 8 species. Jewett (1959) reviewed the stoneflies of the Pacific Northwest and listed 7 species that had type localities in the park: Megaleuctra kincaidi Frison, Doddsia occidentalis (Banks), Soliperla fenderi ( Jewett), Frisonia picticeps (Hanson), Isoperla rainiera Jewett, Megarcys irregularis (Banks), and M. subtruncata (Hanson). Subsequently, Kathroperla takhoma Stark and Surdick (1987) was described from the park. Samples of adult stoneflies from 1994 to 2001 indicate the presence of at least 82 species, with 64% of these typical Pacific Northwest species, and 30 species, or 36%, widespread western North American species. Seventeen new Washington state records are listed, including a substantial range extension for Lednia tumana (Ricker). One undescribed species in the Sweltsa borealis complex was also discovered. We also present illustrations of male terminalia for Despaxia augusta (Banks) and Moselia infuscata (Claassen) to aid in the identification of these species.     

Dam-forming cacti and nitrogen enrichment in a pi?on-juniper woodland in northwestern Arizona

In a pi?on-juniper woodland in northwestern Arizona, connected basal cladodes of a prickly pear cactus ( Opuntia littoralis var. martiniana ) form check dams that cause deposition of N-rich detritus interspaces otherwise lacking litter. Seventy-eight percent of connected basal cladodes measured in transects grew at an angle (with respect to the slope contour) ≤ 45° -an orientation facilitating deposition of flood-borne debris. Soil total N was significantly greater ( P P = 0.0001) compared to adjacent interspaces. Soil total N and organic C above cactus dams were equal to areas beneath canopies (tree and shrub combined). Net NO 3 - (0-5 cm depth) above cactus dams was significantly greater ( P = 0.0001) than below cactus dams, at interspaces, and beneath canopies. Net NH 4 + (0-5 cm soil depth) above cactus dams was significantly greater ( P s ￣x = 0.625, P = 0.0001).     

Nutritional condition of elk in Rocky Mountain National Park

We tested the hypothesis that elk in Rocky Mountain National Park (RMNP) were at ecological carrying capacity by determining herd-specific levels of nutritional condition and fecundity. Ingesta-free body fat levels in adult cows that were lactating were 10.6% ( s = 1.7; range = 6.2-15.4) and 7.7% ( s = 0.5; range = 5.9-10.1) in November 2001 for the Horseshoe and Moraine Park herds, respectively. Cows that were not lactating were able to accrue significantly more body fat: 14.0% ( s = 1.1; range = 7.7-19.3) and 11.5% ( s = 0.8; range = 8.6-15.1) for the Horseshoe and Moraine Park herds, respectively. Cow elk lost most of their body fat over winter (April 2002 levels were 3.9% [ s = 0.4] and 2.9% [ s = 0.4] for the Horseshoe and Moraine Park herds, respectively). Nutritional condition indicated that both Horseshoe Park and Moraine Park elk were well below condition levels elk can achieve on very good-excellent nutrition (i.e., > 15% body fat; Cook et al. 2004) and were comparable to other free-ranging elk populations. However, condition levels were higher than those expected at a ""food-limited"" carrying capacity, and a proportion of elk in each herd were able to achieve condition levels indicative of very good-excellent nutrition. Elk in RMNP are likely regulated and/or limited by a complex combination of density-independent (including significant heterogeneity in forage conditions across RMNP's landscape) and density-dependent processes, as condition levels contradict a simple density-dependent model of a population at ecological carrying capacity.     

Pilfering of stored seeds and the relative costs of scatter-hoarding versus larder-hoarding in yellow pine chipmunks

Yellow pine chipmunks ( Tamias amoenus ) scatter-hoard food during summer and autumn but must form a larder as a winter food source before winter begins. Yellow pine chipmunks do not larder-hoard large quantities of food during the summer, apparently because a summer larder could not be defended from pilferers. We tested the assumption that the rate of pilferage from an unguarded larder would be significantly greater than the rate of pilferage from surface caches (which are also unguarded by yellow pine chipmunks) during the summer and autumn. Buried plastic buckets were used as artificial nests containing larders of 1000 sunflower seeds or 200 Jeffrey pine ( Pinus jeffreyi ) seeds. The pilferage of larder contents was monitored daily and compared to pilferage of surface caches. Animals (yellow pine chipmunks and deer mice, Peromyscus maniculatus ) removed sunflower seeds from caches much faster than from larders, but caches of Jeffrey pine seeds disappeared much more slowly than pine seeds in larders. Further, animals removed pine seeds from larders more quickly than they did sunflower seeds from larders. The difference between seed species was probably because sunflower seeds have much stronger odors, which rodents readily detect, and because chipmunks prefer pine seeds over sunflower seeds. Yellow pine chipmunks must spend a considerable portion of their time foraging for seeds and may not be able to defend a large larder during summer.     

Food and habitat relationships of Claassenia sabulosa (Plecoptera: Perlidae) in the Upper Colorado River, Colorado

Streambed surveys were conducted along the upper Colorado River, Colorado, to describe the distributions of Claassenia sabulosa larvae in relation to current speed and to determine their diets. We also addressed diel feeding periodicity by sampling during both day and night. Claassenia sabulosa was more abundant in riffle habitats than in runs. A positive relationship existed between C. sabulosa abundance and stream current, with larval size increasing with current speed. Chironomidae, Baetidae, and Simulidae collectively accounted for 93% of the prey found in stonefly guts; however, these categories were not consumed equally by all C. sabulosa . Smaller C. sabulosa primarily ate chironomids, and larger individuals consumed more baetids. Only a slight difference existed in the percentage of empty guts between night- and day-collected stoneflies, and ranges of prey per gut at night were higher than those in the day, suggesting that these stoneflies may forage more intensively at night.     

Effects of logging on habitat quality and feeding patterns of Abert squirrels

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} In 1973 a timber harvest of ponderosa pine ( Pinus ponderosa ) was conducted in an area southeast of Monticello, Utah, that is inhabited by Abert squirrels ( Sciurus aberti ). Abert squirrel dietary habits, foraging patterns, and population densities were compared in the timber harvest area and in an adjacent nonharvested area. Squirrel feeding patterns and preferences were visually determined by physical evidence of past feeding. Live-trapping and field-marking of animals were used to determine population density and trends in the two areas. Squirrels fed in only 26.3% of sampled plots on the timber harvest areas, while 42.7% of the uncut area plots showed use (P 50 acres) by clear-cut methods commonly employed by management agencies.     

Number and condition of seeds in ponderosa pine cones in central Arizona

Ponderosa pine cones from 10 areas in Arizona were collected prior to natural seed dispersal and dissected to determine the number of sound, hollow, and insect-damaged seeds in each cone. Total and sound seed yields per cone did not vary significantly among areas but did vary significantly among trees within each area. Numbers of hollow and Megastigmus -infested (Hymenoptera: Torymidae) seeds varied significantly among areas and trees within areas. Numbers of sound seed increased significantly with increasing cone length but did not change with increasing numbers of cones per cluster. The percentages of Megastigmus -infested seed did not change significantly with increasing cone length or number of cones per cluster.     

Mountain ants of Nevada

The nest of the ant Formica propinqua W. M. Wheeler is reported from Washoe Co., Nevada.