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451.
Using standard and internationally validated methods,86 anthropologic characteristics were determined in 650 male(305 from urban areas and 345 from rural areas) and 704 female(331 from urban areas,373 from rural areas) Chinese Hakka adults living in Guangdong and Jiangxi.The data were used to calculate 24 anthropologic indices,which were analyzed statistically.The physical characteristics of Hakka subjects were analyzed and compared with reference ethnic data.There were four main findings of this study.First,a small proportion of Hakka adults had an eye fold on the upper eyelid,but a large proportion had a mongoloid fold.The eye slits were narrow in most adults,had a medium nasal root height and straight bridges,and most of the external angles were prominent.The nasal base was upturned in most men.The distributions of the three types of nasal base in women were similar.The proportions of subjects with middle and high alae nasi heights were high and similar.Males with a maximum nostril diameter were mostly classified as transverse and oblique,while many women were classified as transverse and had relatively wide alae nasi.The round lobe type was the most common.Upper lip skin height was mostly classified as medium.Lips were classified as thin.The hair was black,eyes were brown,and the skin was yellowish.Second,the head length was long in male Hakka.The minimum frontal breadth,face breadth,lip height,and interocular breadth were similar to those of North-Asian populations.Meanwhile,head breadth,morphological facial height,nose breadth,mouth breadth,and nose height were similar to those of South-Asian populations.Head length was long in female Hakka.The minimum frontal breadth,face breadth,lip height,and interocular breadth were similar to those of North-Asian populations.Head breadth,nose breadth,and mouth breadth were similar to those of South-Asian populations.Third,the stature of male and female Hakka in urban and rural areas was classified as medium.The proportions of male and female Hakka classified as mesocephaly(length-breadth index of the head),hypsicephalic type,metriocephalic type(breadth-height index of the head) mesorrhiny,long trunk,subbrachyskelic type,broad shoulder breadth,and narrow distance between iliac crests were higher than those of other types.Finally,principal component analyses showed that the physical characteristics of Hakka were between those of South-Asian and North-Asian ethnic populations,but were generally closer to those of North-Asian populations in China.  相似文献   
452.
A number of basic and applied questions in ecology and environmental management require the characterization of soil and leaf litter faunal diversity. Recent advances in high-throughput sequencing of barcode-gene amplicons (’metabarcoding’) have made it possible to survey biodiversity in a robust and efficient way. However, one obstacle to the widespread adoption of this technique is the need to choose amongst many candidates for bioinformatic processing of the raw sequencing data. We compare three candidate pipelines for the processing of 18S small subunit rDNA metabarcode data from solid substrates: (i) USEARCH/CROP, (ii) Denoiser/UCLUST, and (iii) OCTUPUS. The three pipelines produced reassuringly similar and highly correlated assessments of community composition that are dominated by taxa known to characterize the sampled environments. However, OCTUPUS appears to inflate phylogenetic diversity, because of higher sequence noise. We therefore recommend either the USEARCH/CROP or Denoiser/UCLUST pipelines, both of which can be run within the QIIME (Quantitative Insights Into Microbial Ecology) environment.  相似文献   
453.
Autoimmune pancreatitis(AIP) is a distinct type of chronic pancreatitis with unique clinical,pathological,serological,and imaging features.AIP usually presents with obstructive jaundice.Imaging studies often reveal enlargement of the pancreas with a pancreatic mass and strictures of the main pancreatic duct.Two subtypes of AIP have recently been identified.Type I AIP is more prevalent in elderly Asian males and is characterized by lymphoplasmacytic sclerosing pancreatitis,obliterative phlebitis,and infiltration of large numbers of IgG4-positive plasma cells.Type II AIP is more prevalent in Caucasians and is characterized by granulocyte epithelial lesions.Most patients with type I AIP have a significantly elevated serum IgG4 concentration,which is an important feature for diagnosis and for differentiating between AIP and other conditions such as pancreatic cancer.Extrapancreatic complications are common,such as sclerosing cholangitis,sclerosing sialadenitis,retroperitoneal fibrosis in type I AIP,and ulcerative colitis in type II AIP.A rapid response to glucocorticoids treatment is suggestive of AIP,but the relapse rate is high,warranting the use of immunosuppressant treatment.B-cell depletion with rituximab may be a promising therapy.The prognosis of AIP is generally benign if treated promptly,and spontaneous remission occurs in a proportion of patients.  相似文献   
454.
455.
长春花叶片发育过程中气孔密度和气孔指数的动态变化   总被引:1,自引:0,他引:1  
对长春花叶片近轴面和远轴面上的气孔密度和气孔指数在不同发育阶段的动态变化进行了研究.结果表明:在各个发育阶段,近轴面上的气孔以叶脉两侧居多,远轴面上的气孔则在整个叶片上均匀分布.将一个枝条上的10对真叶按发育顺序界定为10个发育阶段,即从枝条的顶端到基部,分别将第10、第9、第8……第1节位的叶片定义为第1、第2、第3...  相似文献   
456.
大麦种子经5种不同剂量γ射线辐照后, M1植株的花粉母细胞出现多种染色体畸变类型,例如后Ⅰ、后Ⅱ中出现桥、落后,后Ⅰ中出现不对称分裂,后Ⅱ中出现不同步分裂,中期Ⅰ出现环状四价体,末期Ⅰ中有三极分裂和微核,四分体中出现微核且有的微核独立于四分体,从而形成多分体。花粉母细胞的染色体畸变率随剂量的增高而升高,二者呈极显著直线相关关系。 M1花粉母细胞的染色体畸变率与M2的叶绿素突变率及农艺性状变异率呈显著或极显著指数函数关系。 M2花粉母细胞的染色体畸变率低于M1。 Abstract:Barley seeds were irradiated with five different doses of 60 Co-γ ray.There were many kinds of chromosome aberration in pollen mother cells,such as bridge,laggards in anaphase I and anaphase II,asymmetrical division in anaphase I and asynchronous division in anaphase II,ring quadrivalent in metaphase I,three pole division and micro-nuclei in telophase I,micro-nuclei in tetrad and some micro-nucleus separates from the tetrad to form polyad.The frequency of chromosome aberration in pollen mother cells of M1 increased with the increase of dose.There was a significant linear relationship between them.The frequencies of agronomic character mutation and chlorophyll mutation in M2 significantly correlated with the frequencies of chromosome aberration in pollen mother cells of M1 and showed an exponential function.The chromosome aberration frequency in pollen mother cells of M2 was lower than that of M1.  相似文献   
457.
为了研究枯水期鄱阳湖子湖泊轮虫休眠卵空间分布的差异, 于2015年1月份, 在鄱阳湖南矶山湿地自然保护区的南深湖和白沙湖2个子湖泊进行取样调查。研究发现, 不同生境类型中轮虫休眠卵的密度具有显著差异(P<0.05), 轮虫休眠卵的分布具有明显的梯度性, 在洲滩植被区、泥滩区和积水区中轮虫休眠卵的密度逐渐减少。南深湖植被区中轮虫休眠卵的密度最高, 为(3.34±1.28) ind./cm3, 茭白中密度高达5.45 ind./cm3。不同水生植被生境中轮虫休眠卵的密度趋势为: 挺水植物>洲滩植物>浮叶植物>沉水植物。不同水深区轮虫休眠卵的分布不具有明确的规律性。此外, 研究还发现轮虫休眠卵的密度与底泥的软硬程度具有一定相关性, 泥质越软, 轮虫休眠卵的密度越低。  相似文献   
458.
鸟类作为色彩最丰富的陆生脊椎动物,其体表覆盖着颜色多样的羽毛,在伪装、择偶、信号识别等多方面具有重要功能,因此羽毛颜色引起了研究者的极大兴趣。羽毛颜色总体分为由化学物质产生的色素色和由物理结构产生的结构色,其中常见色素有两大类。根据近年来对羽毛色素的研究进展,本文总结了黑色素和类胡萝卜素的类型、合成途径、获取途径以及相关基因,为深入研究羽毛色素合成、代谢的分子调控机制提供科学依据。  相似文献   
459.
栓菌420(Trametes sp. 420)漆酶基因lacD以两种方式在巴斯德毕赤酵母(Pichia pastoris)进行异源表达,产生两种重组漆酶:rLacDx(具有天然N-末端)和rLacDe(N-末端带有8个额外的氨基酸残基)。摇瓶发酵18d,rLacDx和rLacDe的产量分别为1.21×105u/L、7.38×104u/L [以2,2′-连氮-3-乙苯-二噻唑-6磺酸(ABTS)为底物]。在高密度发酵条件下,rLacDx的产量增加到2.39×105u/L,同时其生产周期降至7.5 d。两种重组酶对愈创木酚底物的氧化特性相似,且在50℃和pH3~10的范围内均稳定。然而,rLacDx对底物ABTS的比活力(1761u/mg)高于rLacDe (1122u/mg),其表观Km值(427μmol/L)低于rLacDe (604μmol/L)。  相似文献   
460.
Kaposi's sarcoma-associated herpesvirus (KSHV) is the primary,etiological agent of Kaposi's sarcoma, primary effusion lymphoma and muticentric Castleman's disease. In common with the other herpesviruses, KSHV exhibits both latent and lyric life cycles, both of which are characterized by distinct gene expression profiles and programs. KSHV encodes proteins which play essential roles in the inhibition of host adaptive and innate immunity, the inhibition of apoptosis, and the regulation of the cell cycle. KSHV also encodes several proteins which have transforming and intrcellular signalling activity.  相似文献   
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