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61.
菱属(Trapa L.)的系统分类一直存在较大分歧,至今还没有一个比较公认的分类系统。黑龙江和图们江流域是菱属物种多样性的重要分布区之一,为了揭示该流域菱属植物的地理分布格局和形态多样性,我们进行了大量实地调查和研究。结果显示,从该地区28个湖中共采集到菱属11个种及8个种内变异类型,表明它们具有丰富的形态多样性;结合查阅菱属354份标本资料,共获得92个分布地点数据;采集到的11个物种的地理分布格局呈不均衡性,其中细果野菱(Trapa maximowiczii Korsch.)分布最广,野菱(Trapa incisa Siebold et Zucc.)、兴凯菱(Trapa khankensis Pshennikova)和科热夫尼科夫菱(Trapa kozhevnikovirum Pshennikova)为狭域分布种;东部乌苏里江和图们江流域是菱属物种多样性的分布中心,可能是第四纪冰期避难所;菱属植物多数种间形态特性相对稳定,东北菱(Trapa manshurica Fler.)、耳菱(Trapa potaninii V.Vassil)、丘角菱(Trapa japonica Fler.)、西伯利亚菱(Trapa sibirica Fler.)和细果野菱共有8个种内形态变异类型;种群内多数分类性状稳定,种群间形态变异较明显;菱属植物分布格局不均衡和种内形态变异的形成可能与基因流的扩散限制有关。本研究结果为进一步澄清菱属分类混乱问题奠定了基础,进一步结合分子标记技术研究系统演化关系将对揭示菱属的进化历史具有重要意义。 相似文献
62.
Nucleotide sequence analysis of the human salivary protein genes HIS1 and HIS2, and evolution of the STATH/HIS gene family 总被引:1,自引:0,他引:1
Human histatins are a family of low-M(r), neutral to very basic,
histidine-rich salivary polypeptides. They probably function as part of the
nonimmune host defense system in the oral cavity. A 39-kb region of DNA
containing the HIS1 and HIS2 genes was isolated from two human genomic
phage libraries as a series of overlapping clones. The nucleotide sequences
of the HIS1 gene and part of the HIS2(1) gene were determined. The
transcribed region of HIS1 spans 8.5 kb and contains six exons and five
introns. The HIS1 and HIS2(1) genes exhibit 89% overall sequence identity,
with exon sequences exhibiting 95% identity. The two loci probably arose by
a gene duplication event approximately 15-30 Mya. The HIS1 sequence data
were also compared with that of STATH. Human statherin is a low-M(r) acidic
phosphoprotein that acts as an inhibitor of precipitation of calcium
phosphate salts in the oral cavity. The HIS1 and STATH genes show nearly
identical overall gene structures. The HIS1 and STATH loci exhibit 77%-81%
sequence identity in intron DNA and 80%-88% sequence identity in noncoding
exons but only 38%-43% sequence identity in the protein-coding regions of
exons 4 and 5. These unusual data suggest that HIS1, HIS2, and STATH belong
to a single gene family exhibiting accelerated evolution between the HIS
and STATH coding sequences.
相似文献
63.
64.
Recently, decreased activity levels have been observed in pigs treated postoperatively with transdermal delivery of fentanyl
(TD-fentanyl) after isoflurane anaesthesia. Whether the change in behaviour is related to opioid-induced sedation or to insufficient
pain relief remains to be investigated. This study was therefore undertaken to evaluate the effect of TD-fentanyl 50 μg h-1 on the activity level with and without isoflurane anaesthesia. Eight pigs (25.4 ± 5.2 kg) were submitted to a cross-over
study and given two treatments; 1) fentanyl patch applied after 30 minutes of anaesthesia (treatment A/F) and 2) fentanyl
patch without anaesthesia (treatment F). The pigs' behaviour was observed from a video recording instantaneously every 10
minutes for 24 h before treatments and up to 72 h after the patch attachment. Venous blood samples were taken 1, 6, 12, 24,
48 and 72 h after the patch application. The behaviour recordings showed that TD-fentanyl did not produce sedation in any
pig. No differences were found between the two treatments in activity level, weight gain or serum fentanyl concentration.
This concentration measured after 24 h was 0.27 ± 0.11 ng ml-1 and 0.47 ± 0.40 ng ml-1 in the A/F and F group, respectively. 相似文献
65.
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67.
An increase in bioavailable tin in the environment could result in bioaccumulation thereof in agricultural crops, and therefore, have adverse health consequences on humans that eat these crops. The aims of the current study were thus to assess the uptake of Sn by spinach plants, and the subsequent effects this will have on the uptake of Na, Zn, K, Ca, and Mg as well as the growth of spinach plants. Spinach plants were grown in sand culture and received tin at concentrations of 0.02, 0.2, 2 and 20 mg/L along with a nutrient solution. The uptake of tin at detectible concentrations only occurred at the highest concentrations (2 and 20 mg/L), and it was mostly retained in the roots of the plants. Tin additions also resulted in no visual toxicity symptoms, and might be beneficial to biomass production. Further field trials are needed to ensure that these experimental results remain true under field conditions. 相似文献
68.
Bo Chang Richard S Smith Maureen Peters Olga V Savinova Norman L Hawes Adriana Zabaleta Steven Nusinowitz Janice E Martin Muriel L Davisson Constance L Cepko Brigid LM Hogan Simon WM John 《BMC genetics》2001,2(1):1-12