991 resultados para Keystone XL
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Seven new highly oxygenated nortriterpenoids, rubriflorins D-J (1-7), were isolated from the leaves and stems of Schisandra rubriflora, and their structures were elucidated on the basis of extensive analysis of spectroscopic data. These new compounds feat
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Investigation of an organic extract of Schisandra rubriflora led to the isolation of three new highly oxygenated nortriterpenoids, named rubriflorins A-C (1-3), together with six related known compounds (4-9). Their structures were elucidated by spectrosc
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The acetone extract of Dicranopteris dichotoma afforded two new tetranorclerodanes, 18-hydroxyaylthonic acid (1) and 18-oxo-aylthonic acid (2), and four new clerodane-type diterpene glycosides, (6S,13S)-6-O-[6-O-acetyl-beta-D-glucopyranosyl-(1 -> 4)-alpha
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[GRAPHIC] Przewalskin B (1), a novel diterpenoid possessing a unique skeleton, was isolated from a Chinese medicinal plant Salvia przewalskii. Its structure and relative stereochemistry were elucidated by extensive NMR analysis and a single-crystal X-ray
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Analyses of the mitochondrial cytochrome b gene (1140 bp) showed that Dremomys lokriah, D. pernyi, D. pyrrhomerus, D. rufigenis and D. gularis all are separate species. Dremomys pyrrhomerus showed 8.5% sequence variation from D. rufigenis, and the level o
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The central nervous system exhibits remarkable plasticity in early life. Prenatal morphine exposure may induce adverse behavioral effects on the neonate and the developing offspring. In the present study, we investigated the effect of prenatal morphine exposure (daily from embryonic days 12-16, 20 mg/kg) on 11-day-old chicks using two forms of spatial paradigms: one trial detour behavior task in which animals must bypass an obstacle to reach the desired goal without any training and detour learning task which required several trials of training to reach the detour criterion. The results showed that, on the condition that chicks could successfully detour in the first trial, morphine exposed chicks exhibited longer detour latency to finish the task, coupled by a preference for turning right versus turning left. In contrast, no significant difference in learning and memory was found in detour learning task between morphine exposed chicks and saline chicks. These findings suggest specific behavioral changes associated with prenatal exposure to opioids during mid to late gestation, also raise attention to the possible health hazard from pregnancy drug use in everyday life. (C) 2010 ISDN. Published by Elsevier Ltd. All rights reserved.
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The objective of this study was to provide a simple cryopreservation method for oocytes from Yunnan Yellow Cattle and facilitate preservation efforts in this native Chinese breed, which is threatened by agricultural modernization. Cumulus-oocyte complexes (COCs) were collected from slaughterhouse ovaries and matured in vitro for 22-24 h, then selected for cryopreservation. Vitrification in open pulled straws (OPS) or in microdrops on a cooled metal surface (solid surface vitrification, SSV) was compared. The OPS vitrification solution consisted of 20% ethylene glycol (EG) and 20% DMSO. The SSV solution was a mixture of 35% EG, 5% polyvinyl-pyrrolidon (PVP) and 0.4 M trehalose. Vitrified and warmed oocytes were either fertilized in vitro or parthenogenetically activated. The rates of cleavage and development to blastocysts of fertilized oocytes following OPS versus SSV were not statistically different (38.3 and 12.5% versus 35.8 and 6.0%, respectively). The corresponding rates of parthenogenetic development to blastocysts were also not different (8.2 versus 3.5%, respectively). Development to blastocysts of non-vitrified controls following fertilization was significantly higher than that of the vitrified oocytes (22.6%, P < 0.05). These results demonstrate for the first time, that although both OPS and SSV procedures reduced embryonic development, Yunnan Yellow Cattle oocytes are capable of developing to blastocysts following cryopreservation. (C) 2002 Elsevier Science Inc. All rights reserved.
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Large intestinal obstruction (LIO) in farm animals can cause a ischaemic necrosis of intestinal tissue, eventually leading to death. The roles of endothelin-1 (ET-1) and nitric oxide (NO) are not well understood in the process of LIO, but evidence suggests that endothelial-derived mediators may participate. In the present study, ET-1 concentration and total nitric oxide synthase (NOS) activity were measured in heart, liver, pancreas, lung and kidney in a model of LIO in sheep. Our data demonstrated that ET-1 concentration and NOS activity were altered, with significant increases of ET-1 in heart, lung and kidney and of NOS activity in pancreas and kidney, but a marked decline of NOS activity in liver (p<0.05). It is postulated that these alterations in NOS activity and ET-1 concentration may contribute to the progressive loss of organ function, and finally lead to death in LIO in sheep.
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China is one of the countries with the greatest diversity of nonhuman primate species: 22 species with 30 subspecies, in 6 genera and 3 families. Primatology in China started in 1862, but fruitful study began only in the 1950s. More than 2,000 academic papers have been published, covering systematics, evolution, ecology, etho-ecology, conservation, reproduction and neuroscience. We review primatology in China over the past century, concentrating mostly on systematics, etho-ecology, conservation and reproduction. We aim to share this information with international colleagues and to seek possibilities for collaboration in the future.
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Cryopreservation of domestic animal sperm has been widely used for artificial insemination (AI), and egg yolk is one of the most commonly used cryoprotectants during the freezing-thawing process. The objectives of this study were to compare the effectiven
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Fea's tree rat (Chiromyscus chiropus) is a very rare species which there are only a few specimens in the world. The chromosomes of two male specimens, collected from Xishuanbanna, Yunnan, are analysed by several banding technique (G-, C-bands, as well as Ag-staining). The diploid chromosome number is 22, and autosomes comprise 5 pairs of metacentrics, 2 pairs of subacrocentrics, and 3 pairs of acrocentrics. The X chromosome is a acrocentric, and Y is a micro-chromosome, almost a point, which could be a marker chromosome of the species and the genus. The centromeric C-bands are very faint, and C-bands of Nos. 1, 2, 9 and Y chromosome are negative. Only one pair Ag-NORs was found on No. 10 in the silver-stained karyotype. The relationship between morphologic and chromosomal features was discussed, and C-banded karyotype evolutionary trend has also been discussed. Moreover, the conventional karyotype of Niviventer confucianus was described.
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All gibbons are monogamous and territorial with the exception of Hylobates concolor. This paper reports the coexistence of monogamy and polygyny in black-crested gibbons. Based on the fact of two adult females and two offspring of the same age category in one group and other reasons, we suppose that the two adult females have bred in a single group, i.e. a polygynous one. The other main reasons are: (1) a large home range makes it possible for more individuals to live in one group; (2) mutual tolerance among two females; and (3) selection pressure favouring polygyny.
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Many systematic relationships among Chinese white-toothed shrews of genus Crocidura are presently unresolved. In this paper, a taxonomic revision of Crocidura from Southern China is presented. We studied 338 specimens from Burma, China, Korea, Pakistan, Turkey, Middle and Central Asia, and Russia (Appendix I), 285 of which had complete skulls that were analyzed with principal component and discriminant analyses. Results indicated that 6 species of Crocidura can be recognized in South China. C. fuliginosa occurs in Southwestern and Eastern China, C. attenuata is broadly distributed throughout Southern China, and C. horsfieldii is restricted to the southern part of China. C vorax and C. rapax, usually placed as synonyms of the European C russula, are recognized as 2 valid species whose ranges overlap in Southwestern China. C. shantungensis of Eastern Asia extends to the northern part of Southern China and is distinct from C. suaveolens and C. gmelini of Middle and Central Asia, respectively.
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Phylogenetic relationships among 15 species of wood mice (genus Apodemus) were reconstructed to explore some long-standing taxonomic problems. The results provided support for the monophyly of the genus Apodemus, but could not reject the hypothesis of paraphyly for this genus. Our data divided the 15 species into four major groups: (1) the Sylvaemus group (A. sylvaticus, A. flavicollis, A. alpicola, and A. uralensis), (2) the Apodemus group (A. peninsulae, A. chevreri, A. agrarius, A. speciosus, A. draco, A. ilex, A. semotus, A. latronum, and A. mystacinus), (3) A. argenteus, and (4) A. gurkha. Our results also suggested that orestes should be a valid subspecies of A. draco rather than an independent species; in contrast, A. ilex from Yunnan may be regarded as a separate species rather than a synonym of orestes or draco. The species level status of A. latronum, tscherga as synonyms of A. uralensis, and A. chevrieri as a valid species and the closest sibling species of A. agrarius were further corroborated by our data. Applying a molecular clock with the divergences of Mus and Rattus set at 12 million years ago (Mya) as a calibration point, it was estimated that five old lineages (A. mystacinus and four major groups above) diverged in the late Miocene (7.82-12.74 Mya). Then the Apodemus group (excluding A. mystacinus) split into two subgroups: agrarius and draco, at about 7.17-9.95 Mya. Four species of the Sylvaemus group were estimated to diverge at about 2.92-5.21 Mya. The Hengduan Mountains Region was hypothesized to have played important roles in Apodemus evolutionary histories since the Pleistocene. (C) 2004 Elsevier Inc. All rights reserved.
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The western black crested gibbon (Nomascus concolor), or black gibbon, one of the lesser apes (Hylobatidae), is mainly distributed in Yunnan, China. Of the four recognized subspecies, N. c. jingdongensis is endemic to the Wuliang Mountain, central Yunnan,