大兴安岭天然林不同林分溶解有机碳变化特征

为确定不同林分和季节变化对森林碳库影响。在内蒙古大兴安岭根河林业局境内选取具有代表性的林分,即白桦林、白桦落叶松混交林以及落叶松林为研究对象。收集并测定了树干径流、有机质层和0-30 cm土层中DOC浓度,并分析了DOC变化特征以及不同月份对DOC的影响。结果表明:不同林分中树干径流中DOC平均浓度分别为60.12,172.77,205.02 mg/L;有机质层中DOC平均浓度分别为35.32,39.64,34.45 mg/L;0-30 cm土层中DOC平均浓度分别为26.23,37.08,26.53 mg/L。结果表明:不同林分中DOC浓度表现为树干径流 > 有机质层 > 0-30 cm土层,落叶松林树干径流DOC浓度明显高于白桦林（p<0.05）,且落叶松树干比白桦树干淋溶DOC强;不同林分中有机质层和0-30 cm土层表现为白桦落叶松混交林>白桦林、落叶松林,但无明显的差异（p>0.05）,而且有机质层和土层对DOC有吸附固定作用;不同林分6-9月份树干径流中DOC浓度呈现先升高后降低的趋势,7月份达到最大,机质层和0-30 cm土层中DOC浓度6月份最高,7月、8月最低,而9月份又升高。不同林分和月份的变化,影响了天然林中DOC浓度分布。     

Mapping and validation of the quantitative trait loci for leaf stay‐green‐associated parameters in maize

Functional stay‐green is generally regarded as a desirable trait of varieties in major crops including maize. In this study, we used an F_3:4 recombinant inbred line population with 165 lines from a cross between a stay‐green inbred line (Zheng58) and a model inbred line (B73) using 211 polymorphic simple sequence repeat markers to map quantitative trait loci for three stay‐green‐associated parameters, chlorophyll content, photosystem II photochemical efficiency and stay‐green area, at maturity stage, detected a total of 23 quantitative trait loci (QTL) on nine chromosomes. Single QTL explained 3.7–13.5% of the phenotypic variance. Additionally, we validated some important stay‐green QTL using a heterogeneous inbred family approach and found that the stay‐green‐associated parameters were significantly correlated with the plant yield. This study may contribute to a better insight into the regulatory mechanism behind leaf stay‐green in maize and a novel development of elite maize varieties with delayed leaf senescence through molecular marker‐assisted selection.     

大兴安岭人工林有机质层释放溶解有机碳(DOC)动态特征

溶解有机碳(DOC)是土壤碳库中最活跃的部分。研究人工林生长中有机质层释放DOC的动态,对阐述北方森林碳循环具有基础意义。以空间代替时间方法,在内蒙古大兴安岭根河林业局管辖范围内选取不同林龄人工林为研究对象,收集并测定了有机质层渗透水中DOC浓度,并分析了坡位和不同月份对于有机质层释放DOC的影响。结果表明:不同阶段人工林,有机质层释放DOC浓度呈增加的趋势,且每个样地仅与50年生落叶松人工林阶段DOC有显著差异(P<0.05);在6-9月,有机质层渗透水中DOC浓度随月份变化,整体呈降低趋势,并随着人工林生长,有机质层渗透水中DOC浓度最大值转向7月;在不同坡位中,中、下坡位DOC浓度高于上坡位。随着不同阶段的人工林及坡位和季节的变化,有机质层下DOC浓度发生了一定的变化。     

发酵玉米-豆粕饲料对蛋鸡小肠组织形态、消化酶活性和屏障功能相关基因表达的影响

本试验旨在研究添加不同水平发酵饲料对蛋鸡小肠组织形态、消化酶活性和屏障功能相关基因表达的影响,为发酵饲料在蛋鸡生产中的应用提供参考。以玉米、豆粕和麸皮作为发酵底料,采用复合益生菌进行好氧和厌氧发酵,并通过16s rRNA高通量测序技术,分析发酵前后饲料菌群结构的变化。选取360只健康、体况和产蛋性能基本一致的22周龄京粉6号蛋鸡,随机分为4个组,发酵饲料添加水平分别为0（对照组）、4%、6%和8%,每组6个重复,每个重复15只鸡。试验期29周,其中预试期4周,正试期25周。35和50周龄时测定小肠食糜消化酶活性;试验期末测定小肠绒毛高度和隐窝深度,计算绒隐比（绒毛高度/隐窝深度）,并检测空肠黏膜屏障功能相关基因mRNA相对表达量。结果表明：1）与发酵前相比,发酵后饲料菌群Shannon和Simpson指数显著降低（P<0.05）,表明菌群多样性和丰富度下降;发酵后饲料优势菌群发生改变,在门上水平优势菌为厚壁菌门（Firmicutes）,在属水平上优势菌为魏斯氏菌属（Weissella）。2）与对照组相比,6%和8%发酵饲料添加组蛋鸡十二指肠隐窝深度显著降低（P <0.05）...     

Assessing raindrop impact energy at the forest floor in a mature Japanese cypress plantation using continuous raindrop-sizing instruments

The raindrop size distribution of throughfall and open rainfall was monitored continuously during a rainfall event using laser raindrop-sizing instruments (LD gauges), in order to calculate the raindrop impact energy in a plantation of mature Japanese cypress (Chamaecyparis obtusa), where surface erosion at the forest floor had been a problem. Data from two rainfall events were analyzed. The LD gauges recorded qualitative raindrop size distribution, and the capture rate during each rainfall event was used to manipulate raindrop data quantitatively. Throughfall and open rainfall comparisons revealed several important differences. First, throughfall raindrops were fewer in number and larger in size than open rainfall drops. In one rainfall event, for example, throughfall raindrops were less than one-fifth as frequent as open rainfall raindrops; in addition, the maximum throughfall raindrop diameter was 6.35mm compared to 3.31mm for open rainfall raindrops. Second, throughfall raindrops that were larger than the largest open rainfall raindrops comprised 63.8% of the throughfall precipitation by volume. Third, total raindrop impact energy from throughfall was over twice that of open rainfall. Moreover, comparison of throughfall events implied that throughfall raindrops did not always have a uniform distribution between different events or among different periods of time in one rainfall event, in contrast to findings in previous studies which showed that throughfall raindrops had a uniform size distribution independent of rainfall intensity. It is possible that an abrupt transition of throughfall intensity from low to high changes the distribution of throughfall raindrops.     

Antioxidant constituents in distillation residue of Awamori spirits

Constituents in a distillation residue of Awamori (millet spirits) and their antioxidant activity are investigated in this study. The supernatant of the distillation residue obtained by centrifugation was partitioned with n-hexane, chloroform, ethyl acetate, and n-butanol against water to afford the corresponding solubles. Among them, n-hexane and chloroform solubles showed higher antioxidant potency than l-ascorbic acid by the bleomycin-Fe method. In chloroform solubles, seven cyclic dipeptides were identified along with ethyl 2-pyrrolidione-5-carboxylate, tyrosol, and ethyl p-hydoroxyphenyllactate. Antioxidant activity of ethyl p-hydoroxyphenyllactate was 4.2 times that of l-ascorbic acid, whereas cyclic dipeptides showed activity 0.89-1.29 times as strong as that of l-ascorbic acid. On the other hand, scavenging effect of cyclic dipeptides against O(2)(-.) and OH(.) by using electron spin resonance was also investigated. In the results, cyclo(l-Ile-l-Pro) showed significantly strong inhibitory effect against OH(.) (95.4% at 2.5 x 10-3 M) and cyclo(l-Phe-l-Pro), cyclo(l-Pro-l-Val), and cyclo(l-Leu-l-Pro) inhibited OH(.) 64.9, 54.1, and 51.0%, respectively, whereas alpha-tocopherol showed 37.7% inhibition, though only a few cyclic dipeptides weakly inhibited O(2)(-.).     

A 49-kilodalton phosphoprotein in the Drosophila photoreceptor is an arrestin homolog

The gene encoding the 49-kilodalton protein that undergoes light-induced phosphorylation in the Drosophila photoreceptor has been isolated and characterized. The encoded protein has 401 amino acid residues and a molecular mass of 44,972 daltons, and it shares approximately 42 percent amino acid sequence identity with arrestin (S-antigen), which has been proposed to quench the light-induced cascade of guanosine 3',5'-monophosphate hydrolysis in vertebrate photoreceptors. Unlike the 49-kilodalton protein, however, arrestin, which appears to bind to phosphorylated rhodopsin, has not itself been reported to undergo phosphorylation. In vitro, Ca2+ was the only agent found that would stimulate the phosphorylation of the 49-kilodalton protein. The phosphorylation of this arrestin-like protein in vivo may therefore be triggered by a Ca2+ signal that is likely to be regulated by light-activated phosphoinositide-specific phospholipase C.     

Regulation of mammalian tooth cusp patterning by ectodin

Mammalian tooth crowns have precise functional requirements but cannot be substantially remodeled after eruption. In developing teeth, epithelial signaling centers, the enamel knots, form at future cusp positions and are the first signs of cusp patterns that distinguish species. We report that ectodin, a secreted bone morphogenetic protein (BMP) inhibitor, is expressed as a "negative" image of mouse enamel knots. Furthermore, we show that ectodin-deficient mice have enlarged enamel knots, highly altered cusp patterns, and extra teeth. Unlike in normal teeth, excess BMP accelerates patterning in ectodin-deficient teeth. We propose that ectodin is critical for robust spatial delineation of enamel knots and cusps.