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81.
INTRODUCTIONOpioidactsinthecentralandperipheralnervoussystem(CNSandPNS)to'producenumerouspharmacologicaleffects.Repetitiveorcontinuoususeofopioids,however,causesdrugtoleranceanddependence.Threesubtypesofopioidreceptors,termedp)6,andK,havebeencloned.TheyarecoupledtotheinhibitoryGproteinandnegativelyregulateadenylylcyclasell].RecentlyanewG-proteincoupledreceptortermedopioidreceptor-likereceptor(ORLI)whichbelongstothenewlycharacterizedopioidreceptorsubfamilyhadbeenclonedfromhumanbrainst…  相似文献   
82.
The Chinese crested ibis, Nipponia nippon, is a critically endangered bird. The current population of this species has developed from four wild individuals rediscovered in 1981. Given its conservation status, there is considerable interest in assessing the genetic diversity and individual relatedness in this species. For this purpose, a set of eight polymorphic di‐ or trinucleotide microsatellite loci was developed for the crested ibis. The expected heterozygosity at these loci ranges from 0.01 to 0.50, with less than four alleles being observed at individual loci, a reflection of the serious population bottleneck experienced by this species.  相似文献   
83.
Flowers, microsporogenesis and microgametogenesis of Excentrodendron hsienmu in opening-functional flowers and non-opening flowers were studied to investigate the evolutionary relationships of Excentrodendron . E. hsienmu is a dioecious species that blossoms every 3–4 years, although large numbers of flower buds develop every year. The anther is tetrasporangiate, the tapetum is of the secretory type, the microspore tetrads are mainly tetrahedral, and the pollen grains are two-celled when shed. Four to six microsporocytes are seen on the transverse section of the anthers, and cytokinesis is simultaneous. The development of the anther wall conforms to the basic type and the anther wall is five or six cells thick, with a fibrous endothecium. The difference between the opening-functional and the non-opening flowers is mainly in the thickness of the anther wall. Early megasporogenesis in staminate flowers up to megaspore mother cell or megaspore tetrads has been observed. Excentrodendron shares with Dombeyeae only plesiomorphic features, but differs in anther wall development type and thickness. Most features of Excentrodendron are shared with Pterospermum , including such synapomorphic features as basic type of anther wall development, five- to six-cell-thick anther wall, biseriate tapetum at some places, and degeneration of microsporocytes, suggesting placement near Pterospermum .   © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 447–457.  相似文献   
84.
Temporal auditory mechanisms were measured in killer whales ( Orcinus orca ) by recording auditory evoked potentials (AEPs) to clicks. Clicks were presented at rates from 10/sec to 1,600/sec. At low rates, clicks evoked an AEP similar to the auditory brainstem response (ABR) of other odontocetes; however, peak latencies of the main waves were 3–3.7 msec longer than in bottlenose dolphins. Fourier analysis of the ABR showed a prominent peak at 300–400 Hz and a smaller one at 800–1,200 Hz. High-rate click presentation (more than 100/sec) evoked a rate-following response (RFR). The RFR amplitude depended little on rate up to 400/sec, decreased at higher rates and became undetectable at 1,120/sec. Fourier analysis showed that RFR fundamental amplitude dependence on frequency closely resembled the ABR spectrum. The fundamental could follow clicks to around 1,000/sec, although higher harmonics of lower rates could arise at frequencies as high as 1,200 Hz. Both RFR fundamental phase dependence on frequency and the response lag after a click train indicated an RFR group delay of around 7.5 msec. This corresponds to the latency of ABR waves PIII-NIV, which indicates the RFR originates as a rhythmic, overlapping ABR sequence. The data suggest the killer whale auditory system can follow high click rates, an ability that may have been selected for as a function of high-frequency hearing and the use of rapid clicks in echolocation.  相似文献   
85.
We investigated the structure of hemal nodes in Saanen goats using immunohistochemical staining. We examined the distribution of CD3 positive T lymphocytes, CD79a positive B lymphocytes, CD68 positive macrophages and S100 protein positive follicular dendritic cells. Hemal nodes of six healty adult female goats were used. Hemal nodes were removed from the thoracic and abdominal cavities. The oval to round hemal nodes were observed especially between the abdominal aorta and vena cava, and near the kidneys and adrenal glands. Tissue sections were stained with Crossmon’s modified triple stain to demonstrate general histological structure. The avidin-biotin-peroxidase technique using anti-CD3, anti-CD79a, anti-CD68 and anti-S100 primary antibodies was used for immunohistochemistry. Many CD3 positive T lymphocytes were found in the germinal center of the lymph follicles and in the lymphatic cords of hemal nodes; CD3 positive cells also were observed in the sinuses. CD79a and CD68 positive cells were found at the germinal center of the lymph follicles. In the lymph follicles near the subcapsular sinuses, CD79a and CD68 positive cells were found especially in e areas bordering the mantle zone. S100 positive cells were found in the lymph follicles, lymphatic cords and sinuses.  相似文献   
86.
This experiment was conducted to study growth performance, carcass characteristics, meat quality and plasma constituents of Campbell drakes fed diets containing different levels of lysine with or without a microbial phytase. Basal vegetable duck all-mash diets were fed during the growing (1- 35 d of age), and finishing period (36 - 56 d of age) and were formulated to contain 0.90% and 0.73% lysine (negative control), respectively. These diets were supplemented or not with L-lysine HCl, which resulted in a dietary lysine level of 0.90, 0.95, 1.01 and 1.06% and 0.73, 0.80, 0.87 and 0.94%, during the growing and finishing period, respectively. Furthermore, the diets were fed with or without 600 FTU phytase (Natuphos®) except for those containing 1.06 and 0.94% lysine during the growing and finishing period, respectively (positive control). A lysine level of 1.01/0.87% in the growing/finishing diet significantly increased BWG and improved FCR of drakes by 2.1 and 1.8%, respectively. Phytase significantly increased BWG by 2.1% and 3.5% after feeding the basal diet and 1.01/0.87% lysine, respectively. Also, FCR was significantly improved by 2.2 and 1.8% of groups fed 0.95/0.80, and 1.01/0.87% lysine, respectively. Phytase as an independent variable increased BWG by 1.8, and improved FCR by 1.0%. Lysine and/or phytase did not affect carcass yield, and meat quality treats as well as plasma constituents of drakes. However, lysine level at 0.95/0.80% and 1.01/0.87% significantly decreased abdominal fat deposition compared to either the negative or the positive control. In conclusion, a lysine level of 1.01/0.87% in the growing/finishing diets for drakes is adequate. After phytase supplementation of the basal diet the BWG at a lysine level of 0.90/0.73% were similar to the positive control (1.06/0.94% lysine). However, the best FCR was obtained after feeding diets containing 1.01/0.87% lysine supplemented with phytase.  相似文献   
87.
Multiple cellular events like dynamic actin reorganization and hydrogen peroxide (H2O2) production were demonstrated to be involved in abscisic acid (ABA)‐induced stomatal closure. However, the relationship between them as well as the underlying mechanisms remains poorly understood. Here, we showed that H2O2 generation is indispensable for ABA induction of actin reorganization in guard cells of Arabidopsis that requires the presence of ARP2/3 complex. H2O2‐induced stomatal closure was delayed in the mutants of arpc4 and arpc5, and the rate of actin reorganization was slowed down in arpc4 and arpc5 in response to H2O2, suggesting that ARP2/3‐mediated actin nucleation is required for H2O2‐induced actin cytoskeleton remodelling. Furthermore, the expression of H2O2 biosynthetic related gene AtrbohD and the accumulation of H2O2 was delayed in response to ABA in arpc4 and arpc5, demonstrating that misregulated actin dynamics affects H2O2 production upon ABA treatment. These results support a possible causal relation between the production of H2O2 and actin dynamics in ABA‐mediated guard cell signalling: ABA triggers H2O2 generation that causes the reorganization of the actin cytoskeleton partially mediated by ARP2/3 complex, and ARP2/3 complex‐mediated actin dynamics may feedback regulate H2O2 production.  相似文献   
88.
LTR-反转录转座子是真核基因组重要的组成部分,能通过RNA中间体完成在基因组上的转座。小麦种子受低能氮离子束注入后能促进其反转录转座子的转录,经不同剂量的氮离子束注入的种子发芽24h和48h后,其中的copia-反转录转座子的转录都有不同程度的提高,最高可达到对照的40倍。用基于反转录转座子扩增多态性和反转录转座子微卫星扩增多态性2种分子标记技术扩增经低能氮离子注入后的小麦DNA,指纹图谱显示出了一定的多态性,这说明低能氮离子束激活了小麦中反转录转座子的转座活性。转座子转录活性的增强可调节其邻近基因的表达和mRNA的拼接,反转录转座子插入到基因组上新的位点后,使基因组上的基因发生了重排,这种重排可能表现为植物表型的改变。因此,推测反转录转座子的转录活性提高和转座激活是产生低能离子束注入生物效应的重要原因之一。  相似文献   
89.
应激刺激对大鼠下丘脑血管升压素mRNA水平的影响   总被引:8,自引:2,他引:8  
陆利民  李海雁 《生理学报》1997,49(5):594-598
实验在给予慢性应激刺激的Sprague Dawlay雄性大鼠中进行,用核酸斑点杂交技术观察大鼠下丘脑组织中血管升压素(AVP)mRNA水平变化,用异羟基洋地黄毒甙(DIG)标记的26个碱基长寡聚核苷酸作为检测探针。结果观察到:在给予电击足底结合噪声的应激刺激之后,尾动脉收缩压逐渐升高,到刺激第5天,刺激组与对照组动物之间尾动脉收缩压差别有统计学显著意义;到刺激第9天,刺激组尾动脉收缩压达最高值;以  相似文献   
90.
球形棕囊藻(Phaeocystis globosa)是近年来北部湾常见的有害藻华原因种,涠洲岛海域作为广西沿海藻华的高发区之一,目前仍缺乏关于该海域球形棕囊藻藻华过程的相关研究。为探究涠洲岛海域球形棕囊藻藻华过程中营养盐的状况及藻华的发生对浮游植物群落组成的影响,对2017年3月下旬涠洲岛周边发生的球形棕囊藻藻华区域进行取样调查。结果表明,藻华期间水体中溶解有机磷含量与细胞及囊体密度呈显著正相关。本次藻华主要受水体中溶解态无机氮含量影响,多个调查站点的无机氮/无机磷(DIN/DIP)<10,且硅酸盐/无机氮(SiO32–/DIN)>1,表明这些站点存在氮限制现象,而氮限制可能是本次藻华消亡的主要因素。调查区域共鉴定出浮游植物4门58种,球形棕囊藻细胞密度最高可达1.04×108 cells/L,占浮游植物总细胞密度的98.28%。球形棕囊藻细胞密度与物种多样性指数存在显著的负相关关系。在营养缺乏条件下,有利于球形棕囊藻成囊的链状硅藻种类具有相对较大的细胞密度。  相似文献   
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