Habenular α5 nicotinic receptor subunit signalling controls nicotine intake

Genetic variation in CHRNA5, the gene encoding the α5 nicotinic acetylcholine receptor subunit, increases vulnerability to tobacco addiction and lung cancer, but the underlying mechanisms are unknown. Here we report markedly increased nicotine intake in mice with a null mutation in Chrna5. This effect was 'rescued' in knockout mice by re-expressing α5 subunits in the medial habenula (MHb), and recapitulated in rats through α5 subunit knockdown in MHb. Remarkably, α5 subunit knockdown in MHb did not alter the rewarding effects of nicotine but abolished the inhibitory effects of higher nicotine doses on brain reward systems. The MHb extends projections almost exclusively to the interpeduncular nucleus (IPN). We found diminished IPN activation in response to nicotine in α5 knockout mice. Further, disruption of IPN signalling increased nicotine intake in rats. Our findings indicate that nicotine activates the habenulo-interpeduncular pathway through α5-containing nAChRs, triggering an inhibitory motivational signal that acts to limit nicotine intake.     

Relationships between vegetation and stomata, and between vegetation and pollen surface soil in Yunnan, Southwest China

Surface pollen and stomata of 61 samples collected in a study area ranging from tropical seasonal rainforest to oak forest(Quercus spinosa) in the Yulong Snow Mountain region in Yunnan,China,are used to distinguish vegetation communities.The results show that tropical seasonal rainforest(and mountain rainforest),south subtropical evergreen broad-leaved forest,and Quercus shrub are distinguished effectively from other vegetation types by analysis of surface pollen.The south subtropical evergreen broad-leaved forest,Pinus kesiya forest and evergreen broadleaf forest are distinguished effectively from other types of vegetation by pollen analysis.However,P.yunnanensis forest is not distinguished from other vegetation types,and P.armandii,P.densata forest and temperate deciduous conifer mixed forest are not distinguished.The over-representation of Pinus pollen is the main reason that these vegetation communities are not distinguished from each other.Conifer stomata analysis is an effective tool for identifying and distinguishing different types of coniferous forest,and this method performs well even with a small number of sampling points.     

Functional consequences of treating turkey liver fructose-1,6-bisphosphatase with penicillin G.

Treatment of turkey liver fructose-1,6--bisphosphatase with penicillin G progressively inactivated the enzyme and desensitized the enzyme toward high substrate inhibition. The treatment also led to reduced sensitivity to AMP inhibition and the loss of cooperative interaction among AMP-binding sites. These altered properties were not reversed by dialysis, but were prevented when treatment with penicillin G was perfomed in the presence of substrate.     

SIRT6 is a histone H3 lysine 9 deacetylase that modulates telomeric chromatin

The Sir2 deacetylase regulates chromatin silencing and lifespan in Saccharomyces cerevisiae. In mice, deficiency for the Sir2 family member SIRT6 leads to a shortened lifespan and a premature ageing-like phenotype. However, the molecular mechanisms of SIRT6 function are unclear. SIRT6 is a chromatin-associated protein, but no enzymatic activity of SIRT6 at chromatin has yet been detected, and the identity of physiological SIRT6 substrates is unknown. Here we show that the human SIRT6 protein is an NAD+-dependent, histone H3 lysine 9 (H3K9) deacetylase that modulates telomeric chromatin. SIRT6 associates specifically with telomeres, and SIRT6 depletion leads to telomere dysfunction with end-to-end chromosomal fusions and premature cellular senescence. Moreover, SIRT6-depleted cells exhibit abnormal telomere structures that resemble defects observed in Werner syndrome, a premature ageing disorder. At telomeric chromatin, SIRT6 deacetylates H3K9 and is required for the stable association of WRN, the factor that is mutated in Werner syndrome. We propose that SIRT6 contributes to the propagation of a specialized chromatin state at mammalian telomeres, which in turn is required for proper telomere metabolism and function. Our findings constitute the first identification of a physiological enzymatic activity of SIRT6, and link chromatin regulation by SIRT6 to telomere maintenance and a human premature ageing syndrome.     

Multistage interband cascade photovoltaic devices with a bandgapof 0.23 eV operating above room temperature

Interband cascade （IC） photovoltaic （PV）device structures, consisting of multiple discrete InAs/GaSb superlattice absorbers sandwiched between electronand hole barriers, were grown by molecular beam epitaxy.Details of the molecular beam epitaxy growth and materialcharacterization of the structures are presented. The dis-crete absorber architecture enables certain advantages, suchas high open-circuit voltage, high collection efficiency,high operating temperature, and smooth integration ofcascade stages with different bandgaps. The two- andthree-stage ICPV devices presented in this article operate atroom temperature with substantial open-circuit voltages ata cutoff wavelength of 5.3 μm （corresponding to a bandgapof 0.23 eV）, the longest ever reported for room temperaturePV devices. The device characteristics indicate a high levelof current matching and demonstrate the advantages of theinterband cascade approach in thermophotovoltaic celldesign.     

Asian summer monsoon precipitation recorded by stalagmite oxygen isotopic composition in the western Loess Plateau during AD1875―2003 and its linkage with ocean-atmosphere system

Based on 5 high-precision ^230Th dates and 103 stable oxygen isotope ratios （51eO） obtained from the top 16 mm of a stalagmite collected from Wanxiang Cave, Wudu, Gansu, variation of monsoonal precipitation in the modern Asian Monsoon （AM） marginal zone over the past 100 years was reconstructed. Comparison of the speleothem δ^18O record with instrumental precipitation data at Wudu in the past 50 years indicates a high parallelism between the two curves, suggesting that the speleothem δ^18O is a good proxy for the AM strength and associated precipitation, controlled by ＂amount effect＂ of the precipitation. Variation of the monsoonal precipitation during the past 100 years can be divided into three stages, increasing from AD 1875 to 1900, then decreasing from AD 1901 to 1946, and increasing again thereafter. This variation is quite similar to that of the Drought/Flooding index archived from Chinese historical documents. This speleothem-derived AM record shows a close association with the Pacific Decadal Oscillation （PDO） between AD 1875 and 1977, with higher monsoonal precipitation corresponding to cold PDO phase and vice versa at decadal timescale. The monsoonal precipitation variation is out of phase with the PDO after AD 1977, probably resulting from the decadal climate jump in the north Pacific occurring at around AD 1976/77. These results demonstrate a strong linkage between the AM and associated precipitation and the Pacific Ocean via ocean/atmosphere interaction. This relationship will aid to forecast future hydrological cycle for the AM monsoon region, and to improve forecasting potential of climatic model with observation data from cave.     

List of Oregon Scolytidae (Coleoptera) and notes on new records

Listed are 121 species of Scolytidae from Oregon. Ten species are reported from Oregon for the first time: Hylastes tenuis Eichhoff, Phloeosinus scopulorum scopulorum Swaine, Phloeosinus hoferi Blackman, Trypodendron betulae Swaine, Xyleborus xylographus (Say), Trypophloeus striatulus (Mannerheim), T. Thatcheri Wood, Procryphalus mucronatus (LeConte), Pityophthorus scalptor Blackman, and Monarthrum dentigerum (LeConte). The second Oregon specimen of an exotic species, Xyleborus californicus Wood, is reported also.     

Spatial organization of northern flying squirrels, Glaucomys sabrinus: territoriality in females?

We determined home-range overlap among northern flying squirrels ( Glaucomys sabrinus ) to assess their spatial organization. We found extensive home-range overlap among females, and though this overlap could reflect social behavior, we found no evidence of attraction among females, with only one instance of den-sharing. Instead, our results suggest that females share foraging areas but may be territorial in portions of the home range, especially around den trees and during young-rearing. Home-range overlap could also result from the extrinsic effect of forest fragmentation due to timber harvest, which might impede dispersal and force squirrels to cluster on remaining fragments of suitable habitat. Determinamos el sobrelapamiento del rango hogareño entre las ardillas voladoras del norte ( Glaucomys sabrinus ) para evaluar su organización espacial. Encontramos un extenso sobrelapamientos en los rangos hogareños entre las hembras; aunque esto podría reflejar su comportamiento social, no encontramos evidencia de atracción entre hembras, y en sólo un caso compartieron su guarida. Vienen su lugar, nuestros resultados sugieren que las hembras comparten áreas de forrajeo pero pueden ser territoriales en ciertas partes de su rango hogareño, particularmente cerca de los árboles donde tienen guaridas y cuando tienen cría. El sobrelapamiento del rango hogareño también podría ser el resultado del efecto extrínseco de la fragmentación forestal debido a la tala de madera, el cual podría impedir la dispersión y forzar a las ardillas a agruparse en fragmentos de hábitat adecuado que queden.