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991.
The dry cold climate in the highland of the eastern Kunlun Mountains in Qinghai Province, north‐western part of China supports the establishment of alpine grassland, consisting of Poaceae and Cyperaceae species and dwarf shrub communities dominated by Potentilla and Krascheninnikovia shrubs. The phytosociological vegetation studies carried out around Lake Heihai (36°00′N/93°26′E, 4446 m a.s.l.) reveals a complex pattern of high mountainous vegetation, including three major vegetation communities. A Polygonum sibiricum community occupies wet and slightly saline sites close to the Heihai lake shoreline and Kobresia robusta and Poa pachyantha communities are characteristic for the drier slopes. These communities differ in ecological conditions, exposure and several characteristic species that form local subunits. Main ecological factors influencing plant growth are moisture coming from glacial melt water and the composition and texture of the surface sediments. The atmospheric circulation (i.e. monsoonal wind system) and the different amount of insolation of the southern and northern slopes are of minor importance for the establishment of the different communities. The reflection of the vegetation composition in the modern pollen rain is generally poor, since the pollen spectrum is highly influenced by the local appearance of taxa. Though the vegetation unit of a alpine steppe can be detected. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
992.
The peopling, origins, and early prehistory of the Americas are topics of intense debate. However, few studies have used human remains to document and interpret patterns of health and lifestyle of Paleoamericans. This study provides the first investigation to characterize oral health in a series of early Holocene skeletal remains from Lagoa Santa, Brazil, a locality containing the remains of some of the earliest inhabitants of South America (10,000–7,000 BP). The sample is composed of 949 teeth and 1925 alveoli from an estimated 113 individuals excavated from 17 archaeological sites located in the State of Minas Gerais. We compare dental caries and abscess prevalence at Lagoa Santa to a large sample of human skeletons from the Western Hemisphere Project (WHP) database using both individual and tooth/alveolus count methods. In addition, antemortem tooth loss and tooth wear were analyzed in Lagoa Santa by sex and age. The results show that Lagoa Santa dental caries and abscess prevalence are significantly higher than observed among other hunter–gatherers included in the WHP database, except when abscess prevalence is considered by individual count. Adult females have less tooth wear coupled with higher prevalence of dental caries and antemortem tooth loss than adult males. These results point to an unexpected record of poor oral health at Lagoa Santa, especially among females. A diet based on a highly cariogenic combination of wild tubers and fruits is suggested as an explanation for the elevated rate, characterizing an early adaptation to a tropical environment in South America. Am J Phys Anthropol 154:11–26, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
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对新疆喀纳斯自然保护区和巴音布鲁克草原的地衣进行了分类学研究,发现一个中国新记录属(木刻衣属Xylographa(Fr.)Fr.)及属下新记录种(平行木刻衣Xylographa parallela(Ach.)Fr.),详细描述了该新记录地衣种的形态解剖、化学特征和生境,并提供了相关彩色图片。 相似文献
997.
Pompe disease is a clinically and genetically heterogeneous autosomal recessive disorder caused by lysosomal acid α-glucosidase (GAA) deficiency. We report on two affected members of a non-consanguineous Caucasian family, including a classical infantile-onset patient with severe cardiomyopathy (IO) and his paternal grandmother with the adult-onset (AO) form. Two compound heterozygous sequence variants of the GAA gene were identified in each patient by mutation analyses (IO = c.1211A > G and c.1798C > T; AO = c.1211A > G and c.692 + 5G > T). For this study, the biochemical phenotype resulting from the missense mutation c.1211A > G in exon 8, which converts a highly conserved aspartate to glycine (p.Asp404Gly), was of specific interest because it had not been reported previously. Western blotting revealed a robust expression of all GAA isoforms in quadriceps muscle of both patients (fully CRIM positive), while enzymatic activity was 3.6% (IO) and 6.6% (AO) of normal controls. To further validate these findings, the c.1211A > G sequence variant was introduced in wild type GAA cDNA and over-expressed in HEK293T cells. Site-directed mutagenesis analyses confirmed that the mutation does not affect processing or expression of GAA protein, but rather impairs enzyme function. Similar results were reported for c.1798C > T (p.Arg600Cys), which further supports the biochemical phenotype observed in IO. The third mutation (c.692 + 5G > T, in intron 3) was predicted to affect normal splicing of the GAA mRNA, and qPCR indeed verified a 4-fold lower mRNA expression in AO. It is concluded that the novel sequence variant c.1211A > G results in full CRIM but significantly lower GAA activity, which in combination with c.1798C > T leads to infantile-onset Pompe disease. We surmise that the difference in disease severity between the two family members in this study is due to a milder effect of the intronic mutation c.692 + 5G > T (vs. c.1798C > T) on phenotype, partially preserving GAA activity and delaying onset in the proband (paternal grandmother). 相似文献
998.
Western Flower Thrips (Frankliniella occidentalis) Transmits Maize Chlorotic Mottle Virus 总被引:2,自引:0,他引:2
Mingfu Zhao Honhing Ho Yixin Wu Yueqiu He Mengjiao Li 《Journal of Phytopathology》2014,162(7-8):532-536
Maize chlorotic mottle virus (MCMV) is one of the co‐infection pathogens that cause corn (maize) lethal necrosis, but the transmission mechanism of MCMV is not yet clear. In order to determine the ability of western flower thrips (Frankliniella occidentalis; WFT) to transmit MCMV, imported maize seeds from Thailand were germinated in an insect‐free greenhouse and the seedlings were tested for the transmission by WFT of chlorotic mottle virus disease. The thrips (WFT), starved for 48 h then allowed to feed for 30 min on maize plants infected with MCMV or asymptomatic maize plants, were transferred to healthy seedlings. After 35 days, the seedlings with WFT from diseased maize plants showed chlorotic mottle symptoms, whereas seedlings with WFT from asymptomatic maize plants remained healthy. A single band of 711 bp was amplified by RT‐PCR using primers MCMV‐F/MCMV‐R from the MCMV‐infected plants and WFT collected from the diseased plants. Sequencing of the amplified product and further sequence comparison indicated that the two viruses from both sources showed 99% similarity of nucleotides and they should be regarded as identical. In addition, isometric particles c. 30 nm in diameter, characteristic of MCMV, were found in the WFT samples from diseased maize plants. Thus, it is concluded that WFT transmits MCMV. Our findings suggest that corn lethal necrosis disease can be controlled or minimized by the eradication of WFT from the field or greenhouses. 相似文献
999.
Restoring forb richness to the northern tallgrass prairie (U.S.A.) is often problematic. A potential solution is the establishment of native forb‐seeded patches that can serve as colonization sites. This study was designed to determine the following: (1) the success at which native forbs sown in small patches can colonize the surrounding vegetation matrix and (2) whether soil amendments (C additions, P fertilization, and seed bank reduction) applied to the seeded sites can facilitate such colonization (patch quality). Colonization was investigated at (1) the immediate surrounding (1 m belt transect, BT) of the seeded sites and (2) in disturbed but not seeded patches located 3 m from the seeded site (out‐plots). Soil amendments did not affect colonization, but native forb density in the BT and out‐plots was correlated to the density of forbs in the seeded sites (r2 = 0.3, p < 0.01). Seeded native forb density in the out‐plots was higher than in the adjacent BT (19 vs. 5 plants/m2), suggesting that competition from the matrix vegetation may be more important in forb colonization than distance from the source. Taller forbs with larger seeds showed advantages in colonization success. This study showed that the colonization of matrix vegetation with native forbs from seeded patches is a viable method for prairie reconstruction but requires the availability of disturbed sites. In most prairies, animal‐generated soil disturbances are common. In their absence, disturbances of the vegetation matrix will need to be added to the management plan. 相似文献
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A new Metapeyssonnelia species that comprises up to 7% bottom cover at shallow‐water reef habitats in southwest Puerto Rico is described herein. It forms conspicuous orange encrustations on hard substrata and does not grow on living coral as does its two Caribbean congeners. The new species possesses conspicuous, to 30 cm in extent, tightly adherent crusts up to 950 μm thick, only hypobasal calcification, hypothallial cells arranged in broad flabellules and superficial (raised) tetrasporangial and carposporangial nemathecia. Tetrasporangia are pedicellate, borne laterally from cup‐like cells that are derived from basal paraphysal cells. Tetrasporangia measure up to 120 μm long and individual carposporangia to 80 μm long. The new species differs from other Metapeyssonnelia species developmentally in that perithallial cells at mid thallus height will divide laterally to form a new hypothallium. Small subunit gene sequences relate the new species to the two Metapeyssonnelia species that are previously known from Puerto Rico. 相似文献