Factors influencing lifespan dependency on agricultural crops by brown bears

Landscape and Ecological Engineering - Investigating factors underlying human-wildlife conflicts in agricultural landscapes is important for both preventing crop damage and wildlife conservation....     

Nerve growth factor-induced glutamate release is via p75 receptor,ceramide, and Ca(2+) from ryanodine receptor in developing cerebellar neurons

Very little is known about the contribution of a low affinity neurotrophin receptor, p75, to neurotransmitter release. Here we show that nerve growth factor (NGF) induced a rapid release of glutamate and an increase of Ca2+ in cerebellar neurons through a p75-dependent pathway. The NGF-induced release occurred even in the presence of the Trk inhibitor K252a. The release caused by NGF but not brain-derived neurotrophic factor was enhanced in neurons overexpressing p75. Further, after transfection of p75-small interfering RNA, which down-regulated the endogenous p75 expression, the NGF-induced release was inhibited, suggesting that the NGF-induced glutamate release was through p75. We found that the NGF-increased Ca2+ was derived from the ryanodine-sensitive Ca2+ receptor and that the NGF-increased Ca2+ was essential for the NGF-induced glutamate release. Furthermore, scyphostatin, a sphingomyelinase inhibitor, blocked the NGF-dependent Ca2+ increase and glutamate release, suggesting that a ceramide produced by sphingomyelinase was required for the NGF-stimulated Ca2+ increase and glutamate release. This action of NGF only occurred in developing neurons whereas the brain-derived neurotrophic factor-mediated Ca2+ increase and glutamate release was observed at the mature neuronal stage. Thus, we demonstrate that NGF-mediated neurotransmitter release via the p75-dependent pathway has an important role in developing neurons.     

Microenvironmental conditions for Japanese alder seedling establishment in a hummocky fen

In this article, we focused on hummocky microtopography as a prominent feature of mires and explored the microenvironmental conditions suitable for alder seedling establishment. Japanese alder (Alnus japonica) forest is widely distributed in wetlands in northern Japan. However, because alder seedlings are rare in mires, alder population dynamics and conditions that favor the establishment of alder seedlings are still unknown. The study was conducted in northern Japan at a site in mesotrophic mire. We surveyed the seedling density, the microenvironmental conditions (light, litter cover, and soil quality), and the density of dispersed seeds in alder forest and in the adjacent herbaceous fen. In addition, we performed a laboratory experiment to examine the germination characteristics of alder. Seedlings grew only on hummocks in alder forest. The percentage of litter cover on hummocks was lower than in hollows, and the density of dispersed seeds in alder forest was much higher than in herbaceous fen. Seeds of Japanese alder germinated under both light and dark conditions, and the germination rate were high under light and high-temperature conditions. Our results suggest that litter cover may inhibit seedling establishment and hummocks that characterized by less litter cover are suitable place for the establishment of seedlings. We conclude that hummocky microtopography and abundant seed rain in the mire enable the establishment of Japanese alder seedlings.     

Modulation of functional properties of KCNQ1 channel by association of KCNE1 and KCNE2

The KCNE proteins (KCNE1 through KCNE5) function as beta-subunits of several voltage-gated K(+) channels. Assembly of KCNQ1 K(+) channel alpha-subunits and KCNE1 underlies cardiac I(Ks), while KCNQ1 interacts with all other members of KCNE forming complexes with different properties. Here we investigated synergic actions of KCNE1 and KCNE2 on functional properties of KCNQ1 heterologously expressed in COS7 cells. Patch-clamp recordings from cells expressing KCNQ1 and KCNE1 exhibited the slowly activating current, while co-expression of KCNQ1 with KCNE2 produced a practically time-independent current. When KCNQ1 was co-expressed with both of KCNE1 and KCNE2, the membrane current exhibited a voltage- and time-dependent current whose characteristics differed substantially from those of the KCNQ1/KCNE1 current. The KCNQ1/KCNE1/KCNE2 current had a more depolarized activation voltage, a faster deactivation kinetics, and a less sensitivity to activation by mefenamic acid. These results suggest that KCNE2 can functionally couple to KCNQ1 even in the presence of KCNE1.     

A hierarchical approach to ecosystem assessment of restoration planning at regional,catchment and local scales in Japan

A hierarchical approach to restoration planning at the regional, catchment and local scales is proposed and examined. Restoration projects limited to a local scale and focused on habitat improvement for individual species ended in failure, which has led to the recognition that there is a need for ecosystem-based management at the landscape level. The first landscape-level restoration in Japan is under way in the Kushiro and Shibetsu River Basins, in northern Japan. However, public consensus on these large-scale restoration projects has not yet matured and there are very few projects that have progressed even as far as mapping to classify intact and disturbed ecosystems. Classification of habitat quality using physical and biological indicators appears to be the core element of analysis of ecological degradation at the regional scale (100–1,000 km²). This mass-screening process is critical to identify areas in potential need of restoration. The causes and mechanisms of ecosystem degradation are then examined at the catchment scale (10–100 km²) by linking material flows and habitat conditions. Direct environmental gradient analysis is useful to determine cause and effect relationships between species and habitat quality. Finally, we recommend implementation of field experiments with a clear hypothesis at the local scale (0.01–1 km²). At this stage, key variables causing degradation of the target ecosystem are manipulated to verify the hypothesis. Based on the results of local-scale analyses, the possibility of restoration success can be evaluated, which directs us to practical schemes for future restoration projects at larger scales.     

Use of layer silicate for protein crystallization: effects of Micromica and chlorite powders in hanging drops

Two kinds of layer silicate powder, Micromica and chlorite, were used to aid protein crystallization by the addition to hanging drops. Using appropriate crystallization buffers, Micromica powder facilitated crystal growth speed for most proteins tested in this study. Furthermore, the addition of Micromica powder to hanging drops allowed the successful crystallization of lysozyme, catalase, concanavalin A, and trypsin even at low protein concentrations and under buffer conditions that otherwise would not generate protein crystals. Except for threonine synthase and apoferritin, the presence of chlorite delayed crystallization but induced the formation of large crystals. X-ray analysis of thaumatin crystals generated by our novel procedure gave better quality data than did that of crystals obtained by a conventional hanging drop method. Our results suggest that the speed of crystal growth and the quality of the corresponding X-ray data may be inversely related, at least for the formation of thaumatin crystals. The effect of Micromica and chlorite powders and the application of layer silicate powder for protein crystallization are discussed.