Bees have magnetic remanence

Honey bees orient to the earth's magnetic field. This ability may be associated with a region of transversely oriented magnetic material in the front of the abdomen. The magnetic moment apparently develops in the pupal state and persists in the adults.     

Zonal ultracentrifuge for the separation of ribosomal subunits

Ribosomal subunits were prepared by means of the Anderson zonal ultracentrifuge. With this technique it is possible to separate more than 300 milligrams of subunits with complete resolution in a single run, as compared with about 2 milligrams with conventional rotors. Superior resolution is achieved in the zonal ultracentrifuge, affording possibilities for the detection and preparation of minor ribosomal components.     

Lead, fluoride, and other elements in bonemeal supplements

The Pb, Cd, F, Al, Cr, Cu, Fe, Mn, Mo, Ni, Ti, and Zn content of 20 commercial bonemeal supplements was determined. Samples were mineralized with nitric and perchloric acids prior to determination of all elements except F, for which a diffusion method was used. Pb and Cd were determined by differential pulse anodic stripping voltammetry, F was measured using an ion selective electrode, and all other elements were determined by inductively coupled argon plasma spectroscopy. The mean recoveries of Pb and F were 97 and 99%, respectively. The concentration range of Pb was 1.5-8.7 microgram/g. Cd was quantitated in only one sample at a level of 2.5 microgram/g; all other samples were estimated to contain less than 0.05 microgram Cd/g. The concentration of F ranged from 261 to 921 microgram/g.     

The tortoise and the goat: Interactions on Aldabra island

Endemic giant tortoises and introduced feral goats are the two major terrestrial herbivores on Aldabra atoll and have similar distributions. The tortoises vastly outnumber the goats, however, and the impact of the goats on the tortoises is minimal. Intraspecific competition is a much greater factor for the tortoises than interspecific competition. Feeding habits are significantly different, goats being primarily browsers and tortoises primarily grazers. Both species affect of the growth forms and regeneration of many plant species, but again due to sheer numbers, the tortoises' impact is much greater than the goats. Direct behavioural interactions between tortoises and goats are rare. Goats may, however, indirectly benefit tortoises by depositing heavy loads of faeces at coastal sleeping sites, thus acting as fertilizing agents, moving nutrients from tortoise-inaccessible to tortoise-accessible areas.     

Rocket launcher mechanism of collaborative actin assembly defined by single-molecule imaging

Interacting sets of actin assembly factors work together in cells, but the underlying mechanisms have remained obscure. We used triple-color single-molecule fluorescence microscopy to image the tumor suppressor adenomatous polyposis coli (APC) and the formin mDia1 during filament assembly. Complexes consisting of APC, mDia1, and actin monomers initiated actin filament formation, overcoming inhibition by capping protein and profilin. Upon filament polymerization, the complexes separated, with mDia1 moving processively on growing barbed ends while APC remained at the site of nucleation. Thus, the two assembly factors directly interact to initiate filament assembly and then separate but retain independent associations with either end of the growing filament.     

Experimental West Nile virus infection in Eastern Screech Owls (Megascops asio)

Eastern Screech Owls (EASOs) were experimentally infected with the pathogenic New York 1999 strain of West Nile virus (WNV) by subcutaneous injection or per os. Two of nine subcutaneously inoculated birds died or were euthanatized on 8 or 9 days postinfection (DPI) after <24 hr of lethargy and recumbency. All subcutaneously inoculated birds developed levels of viremia that are likely infectious to mosquitoes, with peak viremia levels ranging from 10(5.0) to 10(9.6) plaque-forming units/ml. Despite the viremia, the remaining seven birds did not display signs of illness. All birds alive beyond 5 DPI seroconverted, although the morbid birds demonstrated significantly lower antibody titers than the clinically normal birds. Cagemates of infected birds did not become infected. One of five orally exposed EASOs became viremic and seroconverted, whereas WNV infection in the remaining four birds was not evident. All infected birds shed virus via the oral and cloacal route. Early during infection, WNV targeted skin, spleen, esophagus, and skeletal muscle. The two morbid owls had myocardial and skeletal muscle necrosis and mild encephalitis and nephritis, whereas some of the clinically healthy birds that were sacrificed on 14 DPI had myocardial arteritis and renal phlebitis. WNV is a significant pathogen of EASOs, causing pathologic lesions with varying clinical outcomes.     

Interactions between TGFβ1 and cyclic strain in modulation of myofibroblastic differentiation of canine mitral valve interstitial cells in 3D culture

ObjectivesThe mechanisms of myxomatous valve degeneration (MVD) are poorly understood. Transforming growth factor-beta1 (TGFβ1) induces myofibroblastic activation in mitral valve interstitial cells (MVIC) in static 2D culture, but the roles of more physiological 3D matrix and cyclic mechanical strain are unclear. In this paper, we test the hypothesis that cyclic strain and TGFβ1 interact to modify MVIC phenotype in 3D culture.Animals, materials and methodsMVIC were isolated from dogs with and without MVD and cultured for 7 days in type 1 collagen hydrogels with and without 5 ng/ml TGFβ1. MVIC with MVD were subjected to 15% cyclic equibiaxial strain with static cultures serving as controls. Myofibroblastic phenotype was assessed via 3D matrix compaction, cell morphology, and expression of myofibroblastic (TGFβ3, alpha-smooth muscle actin – αSMA) and fibroblastic (vimentin) markers.ResultsExogenous TGFβ1 increased matrix compaction by canine MVIC with and without MVD, which correlated with increased cell spreading and elongation. TGFβ1 increased αSMA and TGFβ3 gene expression, but not vimentin expression, in 15% cyclically stretched MVIC. Conversely, 15% cyclic strain significantly increased vimentin protein and gene expression, but not αSMA or TGFβ3. 15% cyclic strain however was unable to counteract the effects of TGFβ1 stimulation on MVIC.ConclusionsThese results suggest that TGFβ1 induces myofibroblastic differentiation (MVD phenotype) of canine MVIC in 3D culture, while 15% cyclic strain promotes a more fibroblastic phenotype. Mechanical and biochemical interactions likely regulate MVIC phenotype with dose dependence. 3D culture systems can systematically investigate these phenomena and identify their underlying molecular mechanisms.