Targeted mutation of Cyln2 in the Williams syndrome critical region links CLIP-115 haploinsufficiency to neurodevelopmental abnormalities in mice

Williams syndrome is a neurodevelopmental disorder caused by the hemizygous deletion of 1.6 Mb on human chromosome 7q11.23. This region comprises the gene CYLN2, encoding CLIP-115, a microtubule-binding protein of 115 kD. Using a gene-targeting approach, we provide evidence that mice with haploinsufficiency for Cyln2 have features reminiscent of Williams syndrome, including mild growth deficiency, brain abnormalities, hippocampal dysfunction and particular deficits in motor coordination. Absence of CLIP-115 also leads to increased levels of CLIP-170 (a closely related cytoplasmic linker protein) and dynactin at the tips of growing microtubules. This protein redistribution may affect dynein motor regulation and, together with the loss of CLIP-115-specific functions, underlie neurological alterations in Williams syndrome.     

Ultrafast and direct imprint of nanostructures in silicon

The fabrication of micrometre- and nanometre-scale devices in silicon typically involves lithography and etching. These processes are costly and tend to be either limited in their resolution or slow in their throughput. Recent work has demonstrated the possibility of patterning substrates on the nanometre scale by 'imprinting' or directed self-assembly, although an etching step is still required to generate the final structures. We have devised and here demonstrate a rapid technique for patterning nanostructures in silicon that does not require etching. In our technique which -- we call 'laser-assisted direct imprint' (LADI) -- a single excimer laser pulse melts a thin surface layer of silicon, and a mould is embossed into the resulting liquid layer. A variety of structures with resolution better than 10 nm have been imprinted into silicon using LADI, and the embossing time is less than 250 ns. The high resolution and speed of LADI, which we attribute to molten silicon's low viscosity (one-third that of water), could open up a variety of applications and be extended to other materials and processing techniques.     

Apoptosis disables CD31-mediated cell detachment from phagocytes promoting binding and engulfment

Macrophage recognition and ingestion of 'self' cells undergoing apoptosis in vivo protects tissues from the toxic contents of dying cells and modulates macrophage regulation of inflammatory and immune responses. However, the complex molecular mechanisms mediating macrophage discrimination between viable and apoptotic cells are poorly understood. In particular, little is known of why viable nucleated cells are not engulfed by macrophages. To reveal active repulsion of viable cells and to seek specific capture or 'tethering' of apoptotic cells, we studied macrophage binding of viable and apoptotic leukocytes under conditions of flow. We found that homophilic ligation of CD31 (ref. 4) on viable leukocytes promoted their active, temperature-dependent detachment under low shear, whereas such CD31-mediated detachment was disabled in apoptotic leukocytes, promoting tight binding and macrophage ingestion of dying cells. Here we propose that CD31 (also known as platelet-endothelial cell adhesion molecule-1, PECAM-1) is an example of a cell-surface molecule that prevents phagocyte ingestion of closely apposed viable cells by transmitting 'detachment' signals, and which changes function on apoptosis, promoting tethering of dying cells to phagocytes.     

Distribution of the milliped genus Apheloria Chamberlin, 1921; summaries of peripheral localities and ones of A. virginiensis (Drury, 1770) west of the Mississippi River (Polydesmida: Xystodesmidae)

The milliped genus Apheloria occupies a broad area in Québec and Ontario, Canada, and the United States east of the Central Plains, lying generally north of the Gulf Coastal states. It is reported for the 1st time from New Jersey, District of Columbia, Illinois, and Kansas; and the 1st localities are recorded for Massachusetts, Connecticut, South Carolina, Georgia, Alabama, and Wisconsin. The projected distribution encompasses all or parts of the District of Columbia and 27 states, including Vermont and Delaware, where the genus has not been taken; New Hampshire and Mississippi lie outside the range. Chesapeake Bay and the Connecticut River form apparent eastern boundaries in Maryland–Virginia and New England, respectively; the Tennessee River does likewise on the south in northern Alabama. Aside from Arkansas, comparatively few records exist from the 6 projected states of occurrence west of the Mississippi River. Only 1 each is available from Iowa and Kansas, and there are no definite localities in Nebraska, where occurrence is postulated at Omaha, the type locality of Fontaria luminosa Kenyon, 1893. Confirmation with fresh material is necessary, but this name seems referrable to Apheloria and may be senior to either A. virginiensis iowa or A. v. reducta , both by Chamberlin, 1939, if 2 distinct races occur west of the Mississippi River.     

Food of cougars in the Cascade Range of Oregon

Animal and nonanimal items were identified in the digestive tracts of 61 cougars ( Felis concolor ) collected between 1978 and 1984 from the western slopes of the Cascade Range in Oregon. Forty - two (69%) of the cougars were taken by hunters in December and January, 18 (30%) were killed at other times of the year because of their proximity to livestock, and one animal was illegally killed in November. Black-tailed deer ( Odocoileus hemionus columbianus ) was the most common prey item, although domestic sheep ( Ovis airies ), porcupines ( Erethizon dorsatum ), and a variety of small mammals were also recorded. Masticated grass was the most common nonanimal item.      

Notes on mycophagy in four species of mice in the genus Peromyscus

We examined stomach contents of 426 Clethrionomys , 217 C. californicus from western Oregon and 209 C. gapperi from widely scattered areas across North America. Clethrionomys californicus consumed fungi of 28 genera. Clethrionomys gapperi from the Rocky Mountains westward consumed fungi of 23 genera, whereas C. gapperi east of the Rocky Mountains consumed fungi of 7 genera. This study supports the conclusions of an earlier study, limited to Oregon and Washington, that food habits of C. californicus and C. gapperi are more closely related to habitat than to species or subspecies of vole.     

Insights into Operationalizing Communities of Practice from SSM-Based Inquiry Processes

Two systemic inquiries, based on soft systems methodology (SSM), into the potential for using community of practice (CoP) theory by an Australian-government created research and development corporation to change its knowledge management (KM) strategy, are reported. Key staff were engaged in the inquiry into how to build a third-order KM strategy based on CoPs; an exploration of key published work on CoPs yielded four SSM activity models—‘being a community practice system’; ‘doing the work of imagination sub-system’; ‘doing the work of alignment sub-system’ and ‘doing the work of engagement sub-system’. These models can be used as heuristics to aid the purposeful design of CoPs in other settings. SSM, enacted as a systemic inquiry, can be understood as a form of systemic action research, which was well equipped to deal with CoP theory and, when enacted participatively, can generate important systemic insights. The inquiry began the process of fostering an appreciation of third order KM but, on the evidence available, did not lead to on-going commitment to a CoPs-based KM strategy. Future research should acknowledge how the framing of research situations influences the research process, the importance of the design of practice change settings and the limited evidence for purposeful interventions leading to successful CoPs.     

Role of three rodents in forest nitrogen fixation in western Oregon: another aspect of mammal-mycorrhizal fungus-tree mutualism

To determine the role of the California red-backed vole ( Clethrionomys califonicus ), the northern flying squirrel ( Glaucomys sabrinus ), and the deer mouse ( Peromyscus maniculatus ) in the nitrogen cycle of forest stands in western Oregon, bacterial colonies were isolated and purified from feces, and their nitrogen-fixing ability measured by acetylene-reduction assay. The ability of the bacterial species Azospirillum   sp. to withstand freezing was also tested. Fecal extracts were used to test whether fecal pellets can provide the nutrients necessary for growth of the bacteria. All the feces tested contained viable nitrogen-fixing bacteria, and both species can survive drying and one can survive freezing. Azospirillum colonies grew well on liquid medium but required yeast extract for growth and nitrogenase activity. Fecal extracts from flying squirrels and chickarees ( Tamiasciurus douglasi ) were as effective as the yeast. The results suggest another link in the chain of mutualism that unites small mammals, mycorrhizal fungi, and forest trees.