首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
A total of 121 seed samples of cabbage, cauliflower, cress, radish and turnip collected from five localities in Upper Egypt were assayed for their fungal flora. The highest count of fungi was recorded on cabbage seeds (75%), whereas the lowest count was observed on turnip seeds (33%). Thirty-five fungal species and two varieties belonging to 16 genera were identified. The broadest number of species (22 species + 1 variety) were isolated from cress seeds. However, only five species,viz. Aspergillus flavus, A. niger, Penicillium chrysogenum, P. funiculosum andRhizopus stolonifer, were found to be associated with seeds of the five plants. The relative efficacy of aqueous seed extracts against these five fungal species was tested. The antifungal drug Trosyd (tioconazole) was taken as a standard inhibitor. The aqueous extract of cabbage seeds inhibited three fungal species, cress extract two and cauliflower and turnip one species; radish seed extract was ineffective.  相似文献   

2.
Eighty-seven species belonging to 59 genera and 33 plant families identified in the study area are presented. The three families with the most species represented were Labiatae (nine aquatic species), Compositae (seven species), and Salicaceae (seven species). The genera most represented wereMentha (six species),Polygonum (five species), andSalix (five species). Sixty-three folk-medicinal aquatic species (73.3%) had similar therapeutic uses in neighboring countries, while the 24 remaining species (26.7%) did not show therapeutic similarity with their use in other countries. Emerged species (plants rooted in soil under water but which emerge partially above the water’s surface) were the most recorded, while amphibious, submerged, and floating species were the least recorded. The folk-medicinal importance of the recorded aquatic species were classified by rank-order priority (ROP). Twenty-one species (24%) had ROP values higher than 50, indicating the highest popularity level in folk-medicinal potentiality; 26 species (29.9%) had therapeutic effects informed by fewer than three informants and were therefore excluded from further consideration; 40 species (46.1%) had ROP values of less than 50, and were thus classified as nonpopular medicinal plants.  相似文献   

3.
Twenty-two species of benthic hydroids, belonging to ten families and 14 genera, were found in a hydroid collection obtained in the Balleny Islands during the BioRoss expedition with the NIWA research vessel Tangaroa in 2004. Twenty of those species constitute new records for the Balleny Islands, raising the total number of known species in the area to 25. Most are members of the subclass Leptothecata, although the subclass Anthoathecata is also relatively well represented. Kirchenpaueriidae and Sertulariidae constitute families with the greatest numbers of species in the collection, with five species (20%) each. Oswaldella with five species (20%) and Staurotheca with four (16%), were the most diverse genera. Twelve species (63%) are endemic to Antarctic waters, most of them with a circum-Antarctic distribution, and 17 (89%) are restricted to Antarctic or Antarctic/sub-Antarctic waters. Although the Balleny Islands hydroid fauna seems to be a typical Antarctic assemblage, it has some striking peculiarities, namely the absence or low representation of some typical and widespread Antarctic genera (Antarctoscyphus and Schizotricha/Symplectoscyphus, respectively).  相似文献   

4.
Cryptic species have been increasingly revealed in the marine realm through an analytical approach incorporating multiple lines of evidence (e.g., mtDNA, nuclear genes and morphology). Illustrations of cryptic taxa improve our understanding of species diversity and evolutionary histories within marine animals. The pen shell Atrina pectinata is known to exhibit extensive morphological variations that may harbour cryptic diversity. In this study, we investigated A. pectinata populations along the coast of China and one from Japan to explore possible cryptic diversity and hybridization using a combination of mitochondrial (cytochrome c oxidase subunit I, mtCOI) and nuclear (ribosomal internal transcribed spacer, nrITS) genes as well as morphology. Phylogenetic analyses of mtCOI ‘DNA barcoding gene’ sequences resolved six divergent lineages with intralineage divergences between 0.4% and 0.8%. Interlineage sequence differences ranged from 4.3% to 22.0%, suggesting that six candidate cryptic species are present. The nrITS gene revealed five deep lineages with Kimura 2‐parameter distances of 3.7–30.3%. The five nuclear lineages generally corresponded to mtCOI lineages 1–4 and (5 + 6), suggestive of five distinct evolutionary lineages. Multiple nrITS sequences of significant variance were found within an individual, clearly implying recent hybridization events between/among the evolutionary lineages, which contributed to cytonuclear discordance. Morphologically, five morphotypes matched the five genetic lineages, although the intermediates may well blur the boundaries of different morphotypes. This study demonstrates the importance of combining multiple lines of evidence to explore species cryptic diversity and past evolutionary histories.  相似文献   

5.
Based on a linear mixed-effect model, we propose here a non-destructive, rapid and reliable way for estimating leaf area, leaf mass and specific leaf area (SLA) at leaf scale for broadleaf species. For the construction of the model, the product of leaf length by width (LW) was the optimum variable to predict the leaf area of five deciduous broadleaf species in northeast China. In contrast, for species with leaf thickness (T) lower than 0.10 mm, the surface metric of a leaf (e.g., LW or width) was more suitable for predicting leaf mass; and for species with leaf thickness larger than 0.10 mm, the volume metric of a leaf (e.g., the product of length, width and thickness together, LWT) was a better predictor. The linear mixed-effect model was reasonable and accurate in predicting the leaf area and leaf mass of leaves in different seasons and positions within the canopy. The mean MAE% (mean absolute error percent) values were 6.9% (with a scope of 4.1–13.0%) for leaf area and 13.8% (9.9–20.7%) for leaf mass for the five broadleaf species. Furthermore, these models can also be used to effectively estimate SLA at leaf scale, with a mean MAE% value of 11.9% (8.2–14.1%) for the five broadleaf species. We also propose that for the SLA estimation of the five broadleaf species examined, the optimum number of sample leaves necessary for good accuracy and reasonable error was 40–60. The use of the provided method would enable researchers or managers to rapidly and effectively detect the seasonal dynamic of leaf traits (e.g., leaf area, leaf mass or SLA) of the same sample leaves in the future.  相似文献   

6.
Traditionally, plant–pollinator interactions have been interpreted as pollination syndrome. However, the validity of pollination syndrome has been widely doubted in modern studies of pollination ecology. The pollination ecology of five Asian Buddleja species, B. asiatica, B. crispa, B. forrestii, B. macrostachya and B. myriantha, in the Sino‐Himalayan region in Asia, flowering in different local seasons, with scented inflorescences were investigated during 2011 and 2012. These five species exhibited diverse floral traits, with narrow and long corolla tubes and concealed nectar. According to their floral morphology, larger bees and Lepidoptera were expected to be the major pollinators. However, field observations showed that only larger bees (honeybee/bumblebee) were the primary pollinators, ranging from 77.95% to 97.90% of total visits. In this study, floral scents of each species were also analysed using coupled gas chromatography and mass spectrometry (GC‐MS). Although the five Buddleja species emitted differentiated floral scent compositions, our results showed that floral scents of the five species are dominated by substances that can serve as attractive signals to bees, including species‐specific scent compounds and principal compounds with larger relative amounts. This suggests that floral scent compositions are closely associated with the principal pollinator assemblages in these five species. Therefore, we conclude that floral scent compositions rather than floral morphology traits should be used to interpret plant–pollinator interactions in these Asian Buddleja species.  相似文献   

7.
Amplified fragment length polymorphism (AFLP) has been widely used for clone identification, but numerous studies have shown that clonemates do not always present identical AFLP fingerprints. Pairwise AFLP distances that distinguish known clones from nonclones have been used to identify a threshold genetic dissimilarity distance below which samples are considered to represent a single clone. Most studies to date have reported threshold values between 2% and 4%. Here, I determine the consistency of the clonal threshold across five species in the tropical plant genus Piper, and evaluate the sensitivity of genetic diversity indices and estimates of frequency of clonal reproduction to the threshold value selected. I sampled multiple ramets per individual from widely distributed plants for each of the five Piper species to set a threshold at the point where the error rate of clonal assignments was lowest. I then sampled all individuals of each shade‐tolerant species in a 1‐ha plot, and of each light‐demanding species in 25 × 35‐m plot, to estimate the frequency of asexual recruitment in natural populations using a series of different thresholds including the threshold set with the preliminary sampling. Clonal threshold values for the different species ranged from 0% to 5% AFLP genetic dissimilarity distance. To determine the sensitivity of estimates of clonal reproduction, I calculated several clonal diversity indexes for the natural populations of each of the five species guided by the range in clonal threshold values observed across the five Piper species. I show that small changes in the value of the clonal threshold can lead to very different conclusions regarding the level of clonal reproduction in natural populations.  相似文献   

8.
Abstract. Nine species of Electrogena from thirty-one populations were investigated on the basis of five meristic and five ratio characters of the larvae. The attribution of populations to species was checked by a cluster analysis based on the generalized distances between pairs. Groups representing species were then subjected to a multiple discriminant analysis; discriminant functions and loadings were calculated. The correct attribution of individuals to species by the discriminant functions ranged from 97% to 100%. The analysis of discriminant loadings shows which characters contribute more to the discrimination of species. Although many species could be identified with some confidence by a sequential monothetic key based on meristic and qualitative characters, the discriminant analysis improves the effectiveness of identification of all species.  相似文献   

9.
We isolated and characterized 16 microsatellite loci from the blacktip shark, Carcharhinus limbatus, and tested cross‐species amplification in 11 Carcharhinus species and five additional shark genera. Thirty‐six (1.6%) and 180 (48%) colonies were positive for dinucleotide repeat motifs from unenriched and enriched libraries, respectively. Heterozygosities of polymorphic loci ranged from 0.04 to 0.96 with two to 22 alleles per locus. Amplification products were observed at nine to 13 loci (five to 11 of which where polymorphic) in 10 Carcharhinus species. Several loci were also polymorphic in each of the additional genera examined.  相似文献   

10.
Since 1995, Trichinella larvae have been detected in 39.5% of farmed crocodiles (Crocodylus niloticus) in Zimbabwe. Morphological, biological, biochemical and molecular studies carried out on one isolate from a farmed crocodile in 2001 support the conclusion that this parasite belongs to a new species, which has been named Trichinella zimbabwensis n.sp. This species, whose larvae are non-encapsulated in host muscles, infects both reptiles and mammals. The morphology of adults and larvae is similar to that of Trichinella papuae. Adults of T. zimbabwensis cross in both directions with adults of T. papuae (i.e. male of T. zimbabwensis per female of T. papuae and male of T. papuae per female of T. zimbabwensis), producing F1 offspring which produce very few and less viable F2 larvae. Muscle larvae of T. zimbabwensis, like those of T. papuae, do not infect birds. Three allozymes (of a total of 10) are diagnostic between T. zimbabwensis and T. papuae, and five are diagnostic between T. zimbabwensis and Trichinella pseudospiralis, the third non-encapsulated species. The percentage of the pairwise alignment identity between T. zimbabwensis and the other Trichinella species for the cytochrome oxidase subunit I gene, the large subunit ribosomal-DNA (mt-lsrDNA) gene and the expansion segment five, shows that T. zimbabwensis is more similar to the two non-encapsulated species T. papuae (91% for cytochrome oxidase I; 96% for mt-lsrDNA; and 88% for expansion segment five) and T. pseudospiralis (88% for cytochrome oxidase I; 90% for mt-lsrDNA; and 66–73% for expansion segment five) than to any of the encapsulated species (85–86% for cytochrome oxidase I; 88–89% for mt-lsrDNA; and 71–79% for expansion segment five). This is the first non-encapsulated species discovered in Africa. The finding of a new Trichinella species that infects both reptiles and mammals suggests that the origin of Trichinella parasites dates back further than previously believed and can contribute to understanding the phylogeny and the epidemiology of the genus Trichinella.  相似文献   

11.
Successful multiparasitism by five parasitoid wasps of the scale insectNipponaclerda biwakoensis was investigated at a reed bed in Lake Biwa. The wasps were gregarious endoparasitoids consuming the entire body of the host. The rate of successful multiparasitism for a parasitoid species was defined as the proportion of the number of individual hosts from which the species emergedwith other species to the total number of hosts from which the species emerged. The rates were high for each parasitoid species, ranging from 17 to 82%. Successful multiparasitism frequently involved two species with similar adult size, but rarely involved species with different adult size. For four of the five species, the number of wasps per host was significantly less when wasps emerged from a host with other species relative to when emerged alone. For the other one species, the number of wasps was less, but the difference was not significant. With only one species, female wasps were significantly smaller when they emerged from a host with other species relative to when emerged alone.  相似文献   

12.
以桂西北石灰岩地区连片出露石丛生境次生林群落为研究对象, 运用稳定性氢氧同位素技术结合IsoSource模型, 分析了5种典型植物(半落叶乔木粉苹婆(Sterculia euosma)、落叶乔木菜豆树(Radermachera sinica)、常绿灌木鹅掌柴(Schefflera octophylla)以及落叶灌木红背山麻杆(Alchornea trewioides)和紫弹树(Celtis biondii))水分来源的季节性差异。结果表明: 雨季, 除鹅掌柴同时利用部分前期雨水外, 其余4种植物均主要利用最近15天内的雨水(利用比例的平均值之和均超过80%)。旱季, 5种植物均主要利用最近一次雨水与前期雨水(一个月前)的混合(利用比例的平均值之和均超过80%), 其中乔木和常绿灌木对前期雨水的利用比例更高(利用比例的平均值均超过50%)。植被良好的石灰岩连片出露石丛生境中, 植物主要以不同时期的雨水为主要水源, 这可能与石灰岩发育的裂隙及其储水能力有关。储存在裂隙中的雨水通过植物蒸腾的方式返回大气, 这一良好的水文循环过程应得到充分的保护。  相似文献   

13.
Potential changes in tree species richness and forest community types were evaluated for the eastern United States according to five scenarios of future climate change resulting from a doubling of atmospheric carbon dioxide (CO2). DISTRIB, an empirical model that uses a regression tree analysis approach, was used to generate suitable habitat, or potential future distributions, of 80 common tree species for each scenario. The model assumes that the vegetation and climate are in equilibrium with no barriers to species migration. Combinations of the individual species model outcomes allowed estimates of species richness (from among the 80 species) and forest type (from simple rules) for each of 2100 counties in the eastern United States. Average species richness across all counties may increase slightly with climatic change. This increase tends to be larger as the average temperature of the climate change scenario increases. Dramatic changes in the distribution of potential forest types were modeled. All five scenarios project the extirpation of the spruce–fir forest types from New England. Outputs from only the two least severe scenarios retain aspen–birch, and they are largely reduced. Maple–beech–birch also shows a large reduction in area under all scenarios. By contrast, oak–hickory and oak–pine types were modeled to increase by 34% and 290%, respectively, averaged over the five scenarios. Although many assumptions are made, these modeled outcomes substantially agree with a limited number of predictions from researchers using paleoecological data or other models. Received 12 May 2000; accepted 20 October 2000.  相似文献   

14.
B R Aton 《Biochemistry》1986,25(3):677-680
Bovine rod outer segments were given a series of flashes, each bleaching from 0.1% to 0.4% of the rhodopsin present. 9-cis-Retinal was then added, regenerating the bleaching pigment to isorhodopsin. The phosphorylated pigment species having either four and five or six and eight phosphates were isolated by chromatofocusing. The amounts of rhodopsin and isorhodopsin present in the phosphorylated species were determined spectrally. The species with four and five phosphates per rhodopsin were approximately 50% rhodopsin-50% isorhodopsin. The more highly phosphorylated species were almost entirely isorhodopsin. Presumably, the phosphorylated rhodopsin was phosphorylated without having been bleached. At a 4% bleach level, approximately 0.5 rhodopsin was phosphorylated with four to five phosphates for each rhodopsin that was bleached and phosphorylated.  相似文献   

15.
N. Greig 《Oecologia》1993,93(3):412-420
Absolute number of seeds lost to predispersal seed predators and proportion of total seeds lost per infructescence were compared among five Costa Rican Piper species of different annual fecundities. Mean seed number and mean seed size in the five species were negatively correlated. The impact of predation on these species was inversely related to the number of seeds they produced. The two early successional species had very high fecundities, a combination of many seeds per infructescence, many infructescences per plant, and, in one species, year-round reproduction. Although seed predators destroyed as many or more seeds of these early successional species than they did of the less fecund, late successional species, this loss accounted for a relatively minor proportion (9 and 12%) of the seeds of the early successional species. In contrast, late successional species produced fewer, larger seeds in a smaller number of infructescences and were not continually in fruit. One of these species, which produced intermediate numbers of intermediately sized seeds, lost 30% of the seeds in each infructescence on average. Seed predators destroyed a larger proportion (65 and 76%) of the seeds per infructescence in the two species with fewest seeds per infructescence. High levels of insect damage in these late successional species caused many of their infructescences to abort prematurely. Taken together these factors resulted in annual fecundities several orders of magnitude smaller in shade-tolerant Piper species than the annual fecundities of shade-intolerant, early successional species. Seedlings of the two early successional species were common in large gaps and other sunny clearings and seedlings of the species with 30% seed loss were occasional, whereas no seedlings were seen of the two species with the highest proportional seed loss, suggesting that seed predation on the latter species may limit seedling recruitment.  相似文献   

16.
青海玉树高原不同生境类型蝶类群落结构与多样性   总被引:1,自引:0,他引:1  
2016年和2017年的5—8月,在玉树市选取森林、灌木、高寒灌丛、高寒草甸草原和裸岩5种生境进行蝴蝶种类资源和群落多样性的调查,共记录到蝶类个体数1580头,62种,隶属于7科40属。其中古北界19种,占总种数的30%,东洋界2种,占总种数的3%,两界共有种(广布种) 41种,占总种数的67%。蛱蝶科(535只)个体数量最多,占蝶类个体总数的34%。计算并分析了5种生境中蝴蝶多样性指数(H')、优势度指数(D)、物种丰富度指数(R)、均匀度指数(J)和相似性系数(I),结果表明:灌木生境具有最高的多样性指数,较高均匀度指数和物种丰富度指数以及最低的优势度指数;高寒草甸草原蝶类的多样性指数、均匀度指数、物种丰富度指数均为最低,而优势度指数最高。  相似文献   

17.
Genetic similarity among fifty species of genus Medicago constituting 197 accessions is described. Pooled zymogram clustering revealed Medicago monantha and Medicago medicaginoides of section Buceras distantly related to other species. At least three groups of species exhibited considerable similarity (>60%) to a major cluster of 32 species wherein five groups comprising 2–17 species with 65–71% similarity were observed. All five subspecies of Medicago sativa showed close affinity with Medicago shepardii. So far, limited success in generating inter-specific crosses in genus Medicago is supported that accessions belonging to individual species are largely grouped together, indicating incompatibility among species under study. Species of Medicago section clustered with species of sections Spirocarpos, Lunatae, Buceras, Heynianane while species of sections Hymerocarpos, Lupularia and Orbiculares clustered solely with species of Spirocarpos. Most clusters were supported with moderate bootstrap values (≥30) and Mantel’s test. Results demonstrate utility of isoenzyme based clustering in plant systematics and breeding.  相似文献   

18.
五种鳗鲡的含肉率及肌肉营养成分分析   总被引:1,自引:0,他引:1  
&#  &#  &#  &#  &#  &#  &#  &# 《水生生物学报》2015,39(4):714-722
研究利用营养测试方法对日本鳗鲡、欧洲鳗鲡、美洲鳗鲡、花鳗鲡和太平洋双色鳗鲡共5种养殖鳗鲡的含肉率及肌肉营养成分进行了分析比较。结果表明: 5种鳗鲡含肉率61.77%69.22%, 日本鳗鲡和太平洋双色鳗鲡显著高于欧洲鳗鲡和花鳗鲡 (P0.05); 水分含量为62.34%71.80%, 粗蛋白含量为11.31% 18.47%, 脂肪含量为8.62% 24.48%, 灰分含量为0.92%1.06%; 均含有18种氨基酸, 其中包括8种人体必须氨基酸, 总氨基酸含量存在差异, 鲜味氨基酸含量占37.43%38.77%, 必需氨基酸指数(EAAI)为65.2574.77, 其构成比例符合FAO/ WHO的标准, 色氨酸、异亮氨基酸和缬氨酸等氨基酸为限制性氨基酸; 富含磷、钾、铁和锌等多种矿物元素, 日本鳗鲡和花鳗鲡含量最高; 均含有16种脂肪酸, 其中饱和脂肪酸(SFA) 7种, 不饱和脂肪酸(UFA)9种; 脂肪酸中多不饱和脂肪酸(PUFA)和二十二碳六烯酸(DHA)含量较高, 分别占总量的41.92%48.27%和6.63%16.87%。研究结果表明: 5种鳗鲡的肌肉为高蛋白、鲜味氨基酸与必需氨基酸含量高的优质蛋白源; 富含磷、钾、铁、锌等矿物元素, 可作为补充人体矿物质营养的膳食来源; 脂肪酸以不饱和脂肪酸为主, 多不饱和脂肪酸和DHA比值高。因此, 5种鳗鲡具有较高的营养价值且有益人体健康, 均是优良的水产养殖种类。    相似文献   

19.
Unigene derived microsatellite markers for the cereal genomes   总被引:6,自引:0,他引:6  
Unigene derived microsatellite (UGMS) markers have the advantage of assaying variation in the expressed component of the genome with unique identity and positions. We characterized the microsatellite motifs present in the unigenes of five cereal species namely, rice, wheat, maize, Sorghum and barley and compared with those in Arabidopsis. The overall UGMS frequency in the five cereal species was 1/7.6 kb. The maximum UGMS frequency was in rice (1/3.6 kb) and the lowest in wheat (1/10.6 kb). GC-rich trinucleotide repeat motifs coding for alanine followed by arginine and the dinucleotide repeat motif GA were found to be abundant UGMS classes across all the five cereal species. Primers could be designed for 95% (wheat and barley) to 97% (rice) of the identified microsatellites. The proportion and frequency of occurrence of long hypervariable class I (≥20 nucleotides) and potentially variable class II (12–20 nucleotides) UGMS across five cereal species were characterized. The class I UGMS markers were physically mapped in silico on to the finished rice genome and bin-mapped in wheat. Comparative mapping based on class I UGMS markers in rice and wheat revealed syntenic relationships between the two genomes. High degree of conservation and cross-transferability of the class I UGMS markers were evident among the five cereal species, which was validated experimentally. The class I UGMS-conserved orthologous set (COS) markers identified in this study would be useful for understanding the evolution of genes and genomes in cereals. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.  相似文献   

20.
Thirty-five inter-simple sequence repeat (ISSR) markers were used to analyze the genetic variation in Cymbidium spp. High number of polymorphic bands (217) with overall 90 % of polymorphism at inter-specific level was observed. Cumulative genetic similarity ranged from 0.40–0.93 with an average value of 66 % among the species. At intra-specific level, average polymorphism detected, ranged from 29.8 to 69.9 % within the five species of Cymbidium. All the species were apparently endowed with low genetic variation at intra-specific level compared to inter-specific level. UPGMA clustering evidently distinguished the representatives of C. aloifolium and C. tigrinum which may be linked to entirely different climatic conditions in which they grow, besides their discrete morphological characteristics. Nine ISSR primers revealed 11 unique species-specific banding patterns belonging to three Cymbidiums, which can further developed as SCAR markers. Thus, present investigation provides valuable baseline data of genetic variation in five species of Cymbidium and addresses the conservation concerns of this horticulturally important orchid.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号