Nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty liver disease are increasing in adults and are likely to be increasing in children. Both conditions are hepatic manifestations of metabolic syndrome. Experimental animals fed fructose-enriched diets are widely recognized as good models for metabolic syndrome. However, few reports have described the hepatic pathology of these experimental animals. In this study, 5-wk-old Wistar specific pathogen-free rats, which are a normal strain, were fed experimental diets for 5 wk. We then evaluated the degree of steatohepatitis. The 5 diet groups were as follows: cornstarch (70% wt:wt) [control (C)], high-fructose (70%) (HFr), high-sucrose (70%) (HS), high-fat (15%) (HF), and high-fat (15%) high-fructose (50%) (HFHFr) diets. The macrovesicular steatosis grade, liver:body weight ratio, and hepatic triglyceride concentration were significantly higher in the HFr group than in the other 4 groups. However, the HFr group had a significantly lower ratio of epididymal white fat:body weight than the other 4 groups and had a lower final body weight than the HF and HFHFr groups. The HF group had a greater final body weight than the C, HFr, and HS groups, but no macrovesicular steatosis was observed. The HFr group had a significantly higher grade of lobular inflammation than the other 4 groups. The distribution of lobular inflammation was predominant over portal inflammation, which is consistent with human NASH. In conclusion, rats fed fructose-enriched diets are a better model for NASH than rats fed fat-enriched diets.

The thalamus receives input from 3 distinct cortical layers, but input from only 2 of these has been well characterized. We therefore investigated whether the third input, derived from layer 6b, is more similar to the projections from layer 6a or layer 5. We studied the projections of a restricted population of deep layer 6 cells (“layer 6b cells”) taking advantage of the transgenic mouse Tg(Drd1a-cre)FK164Gsat/Mmucd (Drd1a-Cre), that selectively expresses Cre-recombinase in a subpopulation of layer 6b neurons across the entire cortical mantle. At P8, 18% of layer 6b neurons are labeled with Drd1a-Cre::tdTomato in somatosensory cortex (SS), and some co-express known layer 6b markers. Using Cre-dependent viral tracing, we identified topographical projections to higher order thalamic nuclei. VGluT1+ synapses formed by labeled layer 6b projections were found in posterior thalamic nucleus (Po) but not in the (pre)thalamic reticular nucleus (TRN). The lack of TRN collaterals was confirmed with single-cell tracing from SS. Transmission electron microscopy comparison of terminal varicosities from layer 5 and layer 6b axons in Po showed that L6b varicosities are markedly smaller and simpler than the majority from L5. Our results suggest that L6b projections to the thalamus are distinct from both L5 and L6a projections.

In the process of neuronal wiring, axons derived from the same functional group typically extend together, resulting in fascicle formation. How these axons communicate with one another remains largely unknown. Here, we show that protocadherin-17 (Pcdh17) supports this group extension by recruiting actin polymerization regulators to interaxonal contact sites. Pcdh17 is expressed by a subset of amygdala neurons, and it accumulates at axon-axon boundaries because of homophilic binding. Pcdh17 knockout in mice suppressed the extension of these axons. Ectopically expressed Pcdh17 altered the pattern of axon extension. In in-vitro cultures, wild-type growth cones normally migrate along other axons, whereas Pcdh17 null growth cones do not. Pcdh17 recruits the WAVE complex, Lamellipodin, and Ena/VASP to cell-cell contacts, converting these sites into motile structures. We propose that, through these mechanisms, Pcdh17 maintains the migration of growth cones that are in contact with other axons, thereby supporting their collective extension.

Mutations in the X-linked gene Protocadherin-19 (Pcdh19) cause female-limited epilepsy and mental retardation in humans. Although Pcdh19 is known to be a homophilic cell-cell adhesion molecule, how its mutations bring about female-specific disorders remains elusive. Here, we report the effects of Pcdh19 knockout in mice on their development and behavior. Pcdh19 was expressed in various brain regions including the cerebral cortex and hippocampus. Although Pcdh19-positive cells were evenly distributed in layer V of wild-type cortices, their distribution became a mosaic in Pcdh19 heterozygous female cortices. In cortical and hippocampal neurons, Pcdh19 was localized along their dendrites, showing occasional accumulation on synapses. Pcdh19 mutants, however, displayed no detectable abnormalities in dendrite and spine morphology of layer V neurons. Nevertheless, Pcdh19 hemizygous males and heterozygous females showed impaired behaviors including activity defects under stress conditions. Notably, only heterozygous females exhibited decreased fear responses. In addition, Pcdh19 overexpression in wild-type cortices led to ectopic clustering of Pcdh19-positive neurons. These results suggest that Pcdh19 is required for behavioral control in mice, but its genetic loss differentially affects the male and female behavior, as seen in human, and they also support the hypothesis that the mosaic expression of Pcdh19 in brains perturbs neuronal interactions.

No abstract

The AGS spectrometer experiment E-802 has measured transverse mass spectra for charged hadrons over a wide rapidity interval in Si+Au, Si+Cu, and Si+Al reactions at 14.6A G Ve/c. These results are compared for two difFerent trigger conditions: central collisions corresponding to 7% of the inelastic cross section selected on multiplicity of charged particles and peripheral collisions corresponding to roughly 50'Fo of the inelastic cross section selected on high kinetic energy at zero degrees. The invariant spectra are well described by exponentials in transverse mass allowing the extraction of rapidity distributions and inverse slope parameters for each specie emitted in the difFerent reactions.PACS number(s): 13.85.Ni, 25.75.+r

Synaptosomal associated protein 25 kDa (SNAP25) is an essential component of the SNARE complex regulating synaptic vesicle fusion. SNAP25 deficiency has been implicated in a variety of cognitive disorders. We ablated SNAP25 from selected neuronal populations by generating a transgenic mouse (B6-Snap25tm3mcw (Snap25-flox)) with LoxP sites flanking exon5a/5b. In the presence of Cre-recombinase, Snap25-flox is recombined to a truncated transcript. Evoked synaptic vesicle release is severely reduced in Snap25 conditional knockout (cKO) neurons as shown by live cell imaging of synaptic vesicle fusion and whole cell patch clamp recordings in cultured hippocampal neurons. We studied Snap25 cKO in subsets of cortical projection neurons in vivo (L5-Rbp4-Cre; L6-Ntsr1-Cre; L6b-Drd1a-Cre). cKO neurons develop normal axonal projections, but axons are not maintained appropriately, showing signs of swelling, fragmentation and eventually complete absence. Onset and progression of degeneration are dependent on the neuron type, with L5 cells showing the earliest and most severe axonal loss. Ultrastructural examination revealed that cKO neurites contain autophagosome/lysosome-like structures. Markers of inflammation such as Iba1 and lipofuscin are increased only in adult cKO cortex. Snap25 cKO can provide a model to study genetic interactions with environmental influences in several disorders.

Oscillatory movement of eukaryotic flagella is caused by dynein-driven microtubule sliding in the axoneme. The mechanical feedback from the bending itself is involved in the regulation of dynein activity, the main mechanism of which is thought to be switching of the activity of dynein between the two sides of the central pair microtubules. To test this, we developed an experimental system using elastase-treated axonemes of sperm flagella, which have a large Ca2+-induced principal bend (P-bend) at the base. On photoreleasing ATP from caged ATP, they slid apart into two bundles of doublets. When the distal overlap region of the slid bundles was bent in the direction opposite to the basal P-bend, backward sliding of the thinner bundle was induced along the flagellum including the bent region. The velocity of the backward sliding was significantly lower than that of the forward sliding, supporting the idea that the dynein activity alternated between the two sides of the central pair on bending. Our results show that the combination of the direction of bending and the conformational state of dynein-microtubule interaction induce the switching of the dynein activity in flagella, thus providing the basis for flagellar oscillation.