Extended secondary structure in 5S rRNAs from a sulphur metabolizing archaebacterium, Thermococcus celer

While this sequence shares a significant homology with the 5S RNAs of other archaebacteria and is consistent with current models for the secondary structure of 5S RNAs, it contains three unusual features. The G + C content (72-74%) is significantly higher than other 5S RNAs; the secondary structure is distinguished by unusually stable and extended helical structures and, most important, there is evidence for sequence heterogeneity in the form of complementary base substitutions and precursor processing. This supports recent evidence (Newmann, H., Gierl, A., Tu, J., Leibrock, J., Staiger, D. and Zillig, W. (1983) Mol. Gen. Genet. 192, 66-72) that, like many of the higher eukaryotes, this group of sulphur-metabolizing bacteria may contain multiple 5S RNA genes.     

Mountain roads shift native and non‐native plant species' ranges

Roads are known to act as corridors for dispersal of plant species. With their variable microclimate, role as corridors for species movement and reoccurring disturbance events, they show several characteristics that might influence range dynamics of both native and non‐native species. Previous research on plant species ranges in mountains however seldom included the effects of roads. To study how ranges of native and non‐native species differ between roads and adjacent vegetation, we used a global dataset of plant species composition along mountain roads. We compared average elevation and range width of species, and used generalized linear mixed models (GLMMs) to compile their range optimum and amplitude. We then explored differences between roadside and adjacent plots based on a species’ origin (native vs non‐native) and nitrogen and temperature affinity. Most non‐native species had on average higher elevational ranges and broader amplitudes in roadsides. Higher optima for non‐native species were associated with high nitrogen and temperature affinity. While lowland native species showed patterns comparable to those in non‐native species, highland native species had significantly lower elevational ranges in roadsides compared to the adjacent vegetation. We conclude that roadsides indeed change the elevational ranges of a variety of species. These changes are not limited to the expansion of non‐native species along mountain roads, but also include both upward and downward changes in ranges of native species. Roadsides may thus facilitate upward range shifts, for instance related to climate change, and they could serve as corridors to facilitate migration of alpine species between adjacent high‐elevation areas. We recommend including the effects of mountain roads in species distribution models to fine‐tune the predictions of range changes in a warming climate.     

Anxiety- and depression-like behavior are correlated with leptin and leptin receptor expression in prefrontal cortex of streptozotocin-induced diabetic rats

Anxiety and depression are common in diabetics. Diabetes also may cause reduced leptin levels in the blood. We investigated the relation between diabetes induced anxiety- and depression-like behavior, and leptin and leptin receptor expression levels in diabetic rats. The anxiety- and depression-like behaviors of rats were assessed 4 weeks after intraperitoneal injection of streptozotocin. Diabetic rats exhibited greater anxiety-like behavior; they spent more time in closed branches of the elevated plus maze test and less time in the center cells of the open field arena. Increased depression-like behavior was observed in diabetic rats using the Porsolt swim test. Prefrontal cortex (PFC), blood leptin levels and PFC neuron numbers were decreased, and leptin receptor expression and apoptosis were increased in diabetic rats. Blood corticosterone levels also were increased in diabetic rats. These results indicate that reduction of leptin up-regulates leptin receptor expression and may affect PFC neurons, which eventually triggers anxiety- and depression-like behaviors in diabetic rats.     

Effects of exercise and poor indoor air quality on learning,memory and blood IGF-1 in adolescent mice

It is known that regular aerobic exercise enhances cognitive functions and increases blood insulin-like growth factor 1 (IGF-1) levels. People living in urban areas spend most of their time indoors and indoor air quality can affect health. We investigated the effects of aerobic exercise in poor and good air quality environments on hippocampus and prefrontal cortex (PFC) neurons, anxiety, and spatial learning and memory in adolescent mice. Poor air quality impaired spatial learning and memory; exercise did not affect learning or memory impairment. Exercise in a good air quality environment improved spatial learning and memory. Poor air quality increased apoptosis in the hippocampus and PFC. Both exercised and sedentary groups living in a poor air quality environment had lower serum IGF-1 levels than those living in a good air quality environment. Living in a poor air quality environment has negative effects on the hippocampus, PFC and blood IGF-1 levels in adolescent mice, but exercise did not alter the negative effects of poor air quality.