Effects of cooking on concentrations of polychlorinated dibenzo-p-dioxins and related compounds in fish and meat

We investigated the cooking-induced changes in concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) (dioxins) using mackerel and beef. The concentrations of dioxins (29 congeners) were determined by isomer specific analyses and were compared between uncooked and cooked samples. The cooking procedures examined in this study included grilling as a fillet, boiling as a fillet, and boiling as tsumire (small, hand-rolled balls) for mackerel and boiling as a slice, broiling as a slice, and broiling as a hamburger for beef. Three trials were carried out for each cooking method. Generally, concentrations of dioxins were reduced in every cooking trial. When nondetected congener concentrations were assumed to be half the limit of detection for mackerel, the maximum percentage reductions of total concentrations given as 2,3,7,8-tetraCDD equivalents (TEQ) were 31% in grilling as a slice, 14% in boiling as a slice, and 21% in boiling as tsumire under the conditions of this study. In contrast, for beef, the reductions were 42% in boiling as a slice, 42% in broiling as a slice, and 44% in broiling as a hamburger. These results suggest that ordinary cooking processes with heating undoubtedly reduce the dioxin content in animal products, and the reductions estimated should be considered when dioxin intake is evaluated using contamination data for individual food items.     

Insect sex-pheromone signals mediated by specific combinations of olfactory receptors

We describe two male-specific olfactory receptors (ORs) in the silk moth, Bombyx mori, that are mutually exclusively expressed in a pair of adjacent pheromone-sensitive neurons of male antennae: One is specifically tuned to bombykol, the sex pheromone, and the other to bombykal, its oxidized form. Both pheromone ORs are coexpressed with an OR from the highly conserved insect OR subfamily. This coexpression promotes the functional expression of pheromone receptors and confers ligand-stimulated nonselective cation channel activity. The same effects were also observed for general ORs. Both odorant and pheromone signaling pathways are mediated by means of a common mechanism in insects.     

Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice

In the mammalian retina, a small subset of retinal ganglion cells (RGCs) are intrinsically photosensitive, express the opsin-like protein melanopsin, and project to brain nuclei involved in non-image-forming visual functions such as pupillary light reflex and circadian photoentrainment. We report that in mice with the melanopsin gene ablated, RGCs retrograde-labeled from the suprachiasmatic nuclei were no longer intrinsically photosensitive, although their number, morphology, and projections were unchanged. These animals showed a pupillary light reflex indistinguishable from that of the wild type at low irradiances, but at high irradiances the reflex was incomplete, a pattern that suggests that the melanopsin-associated system and the classical rod/cone system are complementary in function.     

通辽地区水资源系统输入、输出信息的确定

本文基于动态发展的观点，确立了通辽地区水资源系统有限元模拟模型中各单元逐时段系统输入输出信息的计算模型，诸如降雨入汉补给量，潜水蒸发量，河渠和水库引放水渠渗漏量，地下水净开采量及灌溉回归水量等信息都综合考虑了降雨量大小，潜水蒸发强度，河渠流量大小，开采量（或灌溉量）大小和地下水埋深的关系。还考虑了其随时间，空间位置的变化关系。     

Specific GABAA circuits for visual cortical plasticity

Weak inhibition within visual cortex early in life prevents experience-dependent plasticity. Loss of responsiveness to an eye deprived of vision can be initiated prematurely by enhancing gamma-aminobutyric acid (GABA)-mediated transmission with benzodiazepines. Here, we use a mouse "knockin" mutation to alpha subunits that renders individual GABA type A (GABA(A)) receptors insensitive to diazepam to show that a particular inhibitory network controls expression of the critical period. Only alpha1-containing circuits were found to drive cortical plasticity, whereas alpha2-enriched connections separately regulated neuronal firing. This dissociation carries implications for models of brain development and the safe design of benzodiazepines for use in infants.     

Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity

The primary circadian pacemaker, in the suprachiasmatic nucleus (SCN) of the mammalian brain, is photoentrained by light signals from the eyes through the retinohypothalamic tract. Retinal rod and cone cells are not required for photoentrainment. Recent evidence suggests that the entraining photoreceptors are retinal ganglion cells (RGCs) that project to the SCN. The visual pigment for this photoreceptor may be melanopsin, an opsin-like protein whose coding messenger RNA is found in a subset of mammalian RGCs. By cloning rat melanopsin and generating specific antibodies, we show that melanopsin is present in cell bodies, dendrites, and proximal axonal segments of a subset of rat RGCs. In mice heterozygous for tau-lacZ targeted to the melanopsin gene locus, beta-galactosidase-positive RGC axons projected to the SCN and other brain nuclei involved in circadian photoentrainment or the pupillary light reflex. Rat RGCs that exhibited intrinsic photosensitivity invariably expressed melanopsin. Hence, melanopsin is most likely the visual pigment of phototransducing RGCs that set the circadian clock and initiate other non-image-forming visual functions.     

Highly regioselective amination of unactivated alkanes by hypervalent sulfonylimino-λ³-bromane

Amination of alkanes has generally required metal catalysts and/or high temperatures. Here we report that simple exposure of a broad range of alkanes to N-triflylimino-λ(3)-bromane 1 at ambient temperature results in C-H insertion of the nitrogen functionality to afford triflyl-substituted amines in moderate to high yields. Marked selectivity for tertiary over secondary C-H bonds was observed; primary (methyl) C-H bonds were inert. Addition of hexafluoroisopropanol to inhibit decomposition of 1 dramatically improved the C-H amination efficiencies. Second-order kinetics, activation parameters (negative activation entropy), deuterium isotope effects, and theoretical calculations suggest a concerted asynchronous bimolecular transition state for the metal-free C-H amination event.     

鹅掌楸属次生木质部解剖特征及自然种系统演化

比较研究了鹅掌楸属(Liriodendron)中国鹅掌楸、北美鹅掌楸和杂交鹅掌楸3个树种次生木质部的显微构造。经方差分析,3个树种间导管分子、木纤维、轴向薄壁组织和木射线组织等解剖特征存在极显著差异,杂交鹅掌楸次生木质部结构兼具亲本特征。首次发现中国鹅掌楸中存在单穿孔导管,约占4%。中国鹅掌楸较北美鹅掌楸导管分子短、导管端壁穿孔板横隔数少、弦切面木射线组织的宽度、高度小以及轴向薄壁细胞束的细胞个数少。北美鹅掌楸与中国鹅掌楸相比具有更多的原始特征,中国鹅掌楸较北美鹅掌楸进化。