Effects of pesticides on owls in North America

Volume: 30Start Page: 198End Page: 20

Artificial burrows provide new insight into burrowing owl nesting biology

Volume: 15Start Page: 82End Page: 8

Split-crest and immediate implant placement with ultrasonic bone surgery (piezosurgery): 3-year follow-up of 180 treated implant sites

Objective: To report and evaluate ultrasonic bone surgery (USBS), also known as piezosurgery, in split-crest procedures with immediate implant placement at 3 years of follow-up. Method and Materials: Sixty-one split-crest procedures were performed, and 180 implants were placed in 43 patients. Initial ridge width varied between 1.5 and 5.0 mm (mean 3.3 +/- 0.7 mm). Bone density was type I (11.1%), type II (27.8%), type III (28.9%), and type IV (32.2%). The USBS device worked with a 20 to 32 kHz vibrating frequency and 90 W peak power. Results: Mean split length was 14.8 +/- 10.8 mm; mean final ridge width was 6.0 +/- 0.4 mm. At second-stage surgery, five of 180 implants failed to osseointegrate (2.8%), all in the maxilla. Also at second-stage surgery, the success rate of the implants placed simultaneously to the split crest performed with USBS was 97.2% overall, 95.1% in the maxilla and 100% in the mandible. No loaded implant failed during the 3-year followup; respective success rates were unchanged. Conclusions: USBS is predictable to perform split-crest procedures, without risk of bone thermonecrosis; it decreases the risk of soft tissue alteration. Bone-cutting efficiency was satisfactory with the present USBS device because of its elevated ultrasonic vibrating power, especially in soft type IV bone. (Quintessence Int 2010;41:463-469

Heptachlor seed treatment contaminates hawks, owls and eagles of Columbia Basin, Oregon

Volume: 18Start Page: 41End Page: 4

Sharp‐tailed Grouse in the Nebraska Sandhills Select Residual Cover Patches for Nest Sites

We evaluated selection and availability of residual cover (dead standing herbage) by sharptailed grouse (Tympanuchus phasianellus) at time of nest‐site selection in an intact and annually grazed grassland. We used radiotelemetry in 1988–1990 to locate 147 nests in the sandhills of Nebraska, USA, and classified 121 as initial nests and 26 as renests. We used visual obstruction readings (VOR) to measure the height and density of residual cover at nests and 373 landscape‐scale transects around leks (trap sites). We excluded 77 nests from vegetation analysis because green herbage or early livestock grazing compromised residual cover measurements. Most females selected nest sites with residual cover, mostly warm‐season grasses, taller and denser than surrounding vegetation. Visual obstruction readings at 70 nests ( avg x = 7.1 cm, SE = 0.4, range = 1.0–19.0) averaged almost twice the VOR of residual cover within 12m of nests ( avg x = 4.0 cm, SE = 0.3, range = 0.9–11.8) and almost three times the landscape VOR ( avg x = 2.5 cm, SE = 0.1, range = 0.5–7.9). As further evidence of the importance of residual cover, \u3e52% (n \u3e 37) of the females (initial nests) in 1988 and 1989 completed egg‐laying and were incubating before green herbage began contributing to nest cover. More than 88% (n \u3e 42) of the females relied on residual cover through egglaying in 1990 when annual drought delayed foliar development. Interested ranchers and land managers can enhance residual cover through livestock grazing management to attract females and presumably increase nest density, a key component of annual sharp‐tailed grouse productivit

Molecular implications of evolutionary differences in CHD double chromodomains

Double chromodomains occur in CHD proteins, which are ATP-dependent chromatin remodeling factors implicated in RNA polymerase II transcription regulation. Biochemical studies suggest important differences in the histone H3 tail binding of different CHD chromodomains. In human and Drosophila, CHD1 double chromodomains bind lysine 4-methylated histone H3 tail, which is a hallmark of transcriptionally active chromatin in all eukaryotes. Here, we present the crystal structure of the yeast CHD1 double chromodomains, and pinpoint their differences with that of the human CHD1 double chromodomains. The most conserved residues in these double chromodomains are the two chromoboxes that orient adjacently. Only a subset of CHD chromoboxes can form an aromatic cage for methyllysine binding, and methyllysine binding requires correctly oriented inserts. These factors preclude yeast CHD1 double chromodomains from interacting with the histone H3 tail. Despite great sequence similarity between the human CHD1 and CHD2 chromodomains, variation within an insert likely prevents CHD2 double chromodomains from binding lysine 4-methylated histone H3 tail as efficiently as in CHD1. By using the available structural and biochemical data we highlight the evolutionary specialization of CHD double chromodomains, and provide insights about their targeting capacities.status: publishe