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1.
The chromosomal localization of 28S rDNA was investigated in 16 speices of the Australian ant genus Myrmecia, with 2n numbers ranging from 4 to 76, using the fluorescence in situ hybridization method and karyographic analysis. A unique phenomenon was observed: the number of chromosomes carrying 28S rDNA increases from 2 in species with low chromosome numbers to 19 in species with high chromosome numbers. This is termed rDNA dispersion. Centric fission and a reciprocal translocation that occurs in C-bands were detected as the major mechanisms involved in rDNA dispersion. Received: 22 March 1996; in revised form: 3 June 1996 / Accepted: 4 June 1996  相似文献   

2.
Tomato (Lycopersicon esculentum) accession LA1996 with the Anthocyanin fruit (Aft) gene has dark green foliage, elevated anthocyanin expression in the hypocotyls of seedlings, and anthocyanin in the skin and outer pericarp tissues of the fruit. Interest in the health benefits and antioxidant capacity of anthocyanins led to this study of the genetic potential for increased levels of this important class of phytonutrients in tomato fruit. In order to conform to tomato gene nomenclature rules, we propose changing the symbol Af for Anthocyanin fruit to Aft. Segregation ratios of anthocyanin expression in F(2) and BC(1) populations of a cross between the processing tomato UC82B and LA1996 were consistent with a single dominant gene hypothesis. Anthocyanin expression was reduced in backcross populations compared to F(2 )populations. Anthocyanin concentration, as measured by the pH differential method, of pigment-rich pericarp and skin tissues from LA1996 was estimated to be 20.6 mg/100 g and 66.5 mg/100 g, respectively. Anthocyanidin composition was characterized by high-performance liquid chromatography (HPLC). Fruit of accession LA1996 contained predominantly petunidin, followed by malvidin and delphinidinin. Lycopene, beta-carotene, phytoene, and phytofluene levels were similar to those of normal tomatoes and lower than those found in high pigment tomatoes.  相似文献   

3.
Ovules of the wheat breeding line Veery #5 were excised and transferred to culture within 24 h after pollination. When ovules were cultured on Phytagel-solidified medium, and the pericarp removed exclusively at the micropylar tip and the abaxial side, zygotes from up to 79.2% of the ovules underwent embryogenesis with the same developmental pattern as found in planta. Embryos from more than 50% of the cultured ovules germinated when transferred to regeneration medium. More than 100 plantlets were randomly chosen for transfer to soil, all of which developed to phenotypically normal and fertile plants. With this system, the entire process of zygotic embryogenesis can be studied using living material. Furthermore, the method could be used as an embryo rescue technique for plant breeding purposes. Received: 17 June 1996 / Revision received: 22 October 1996 / Accepted: 15 December 1996  相似文献   

4.
Stoat (Mustela erminea) density was estimated by live-trapping in a South Island Nothofagus forest, New Zealand, at 8-9 (Jan/Feb 1996) and 15-16 (Aug/Sep 1996) month intervals after significant beech seedfall in autumn 1995. Absolute densities were 4.2 stoats per km² (2.9-7.7 stoats per km², 95% confidence intervals) in Jan;Feb 1996 and 2.5 stoats per km² (2.1-3.5 stoats per km²) in Aug/Sep 1996. Trappability of stoats increased in the latter sampling period, probably because mice (Mus musculus) had become extremely scarce. accordingly, trapping rates of stoats may vary temporally and spatially with food supply rather than only with absolute abundance. Ship rats (Rattus rattus) capture rates doubled between Jan/Feb 1996 and Aug/Sep 1996, but rapidly declined shortly afterwards. Trappability of ship rats also increased in the latter sampling period. These factors must be considered when planning methods of indexing relative densities of stoats and rats.  相似文献   

5.
Seasonal variations in phytoplankton biomass and productionwere studied in 1996 and 1997 in the newly flooded (1995) SepReservoir (France) in relation to various physico-chemical environmentalfactors. No trophic upsurge occurred in the reservoir as hasbeen found in most of the newly flooded reservoirs. Phytoplanktoncomposition changed drastically from 1996 to 1997, the latteryear being characterized by a rarity of diatoms. Areal euphoticchlorophyll a concentration and phytoplankton carbon biomasswere typical of mesotrophic lakes in 1996 and of somewhat oligotrophicenvironments in 1997. In contrast, the primary production (PP)rates were similar in both years, indicating a change in thefactors controlling phytoplankton populations from 1996 to 1997.The low PP (compared with the algal biomass present) in 1996seemed to be related to the instability of the water columnand the Zmix:Zeu ratio, whose negative effects on the phytoplanktoncommunity were apparently more pronounced in 1996 than in 1997.Orthophosphate concentrations, and their contribution to totalphosphorus, remained low in 1996 but increased with time in1997. The temporal losses of orthophosphates from June to September1996 accounted for only 42% of the measured PP, indicating thatPP in 1996 was also strongly affected by P availability andprobably took place due to other P sources such as regeneratednutrients.  相似文献   

6.
本文记述采自贵州梵净山的蚋属一新种,鞍阳蚋Simulium(Simulium)ephippioidum,新种隶属于多叉蚋组Simulium multistriatum-group。,其两性尾器形态特殊,茧具前侧窗,幼虫后腹节具叶状毛等特征,可与其它已知近缘种相区别。  相似文献   

7.
复合生态系统动态足迹分析   总被引:8,自引:4,他引:8  
王健民  王伟  张毅  胡梦春  唐晓燕  陈敏 《生态学报》2004,24(12):2920-2926
由Rees W E.于1992年提出、由Wackernagel M.于1996年完善的生态占用(生态足迹)原理与方法,其主要成果是评价出全球52个有代表性的国家和地区的生态占用盈亏情况,进一步得出全球人均生态占用阈值为1.74hm^2(量纲,下同)、基准值为2.0hm^2,而人均实际生态占用为2.4hm^2,人均生态赤字达0.4hm^2以上,评价结果表明全球生态环境进人了危机阶段,因此具有重要的预警战略意义。但是该方法也存在一些不足之处,如:(1)主要是反映自然生态系统承载力,未能全面反映出社会经济反馈力(人力、物资、资金、管理等方面的投人效用),尤其是忽略了现代科学技术在提高复合生态系统承载力方面的巨大作用和贡献;(2)将各生态类型加权抽象化后所得到的等量化综合指标,难于反映复合生态系统要素与要素间的复杂变化规律;(3)最初创建的方法未反映动态变化情况:(4)新开发的4种时间序列的方法,仍不能反映复合生态要素间生动地相关关系。针对以上主要缺陷,旨在将复合生态系统进行要素分解,进行要素与时间相关分析及要素间动态相关分析。将社会经济冲击力、自然生态环境资源承载力及社会经济科学技术反馈力三者相结合进行分析综合性研究的基础上,于2002年创建了复合生态系统动态足迹(生态史迹)分析原理、方法和研究案例。鉴于社会经济系统对自然生态系统的冲击力、生态环境资源系统的承载力及社会经济科学技术的反馈力都是在变动的,必需进行复合生态系统动态足迹的相关分析。在做出复合生态系统单要素(含因子,下同)随时间要素动态变化、双要素间动态相关分析的基础上;进一步建立了可反映出复合生态系统冲击力、承载力及反馈力的多要素间动态足迹相关模式图。模式图的基本原理是:反映冲击力的人均生态需求(I/P)应小于或等于复合生态承载力的人均有效生态空间(E/P)与单位有效生态空间产出(I’/E)的乘积。以E/P为横轴、I’/E为纵轴作图,图中各点为I/P;图中系列I/P理论等值线可构成复合生态系统承载力基准和序列标准曲线。模式图的基本功能和作用有:(1)通过理论研究和经验分析,可以绘制出复合生态系统有关要素承载力基准与序列标准曲线;(2)通过历史统计资料,可以绘制出复合生态系统相关生态因子冲击力的动态变化曲线;(3)可以对冲击力与承载力基准与标准序列间进行静态和动态评价;(4)可以对反馈力增加复合生态系统承载力的情况进行评价;(5)进一步再进行针对性的原因分析及包括提高反馈力在内的对策性研究。  相似文献   

8.
A sweet potato (Ipomoea batatas cv. Tainong 57) trypsin inhibitor gene was introduced into tobacco plants (Nicotiana tabaccum cv. W38) by Agrobacterium tumefaciens– mediated transformation. From 30 independent transformants, three lines with high level of expression were further analyzed. The trypsin inhibitor gene, under control of the 35S CaMV promoter, led to the production of the trypsin inhibitor proteins up to 0.2% of the total protein. In insecticidal bioassays of transgenic tobacco plants, larval, growth of Spodoptera litura (F.), the tobacco cutworm, was severely retarded as compared to their growth on control plants. This observation implied that expression of sweet potato trypsin inhibitor can provide an efficient method for crop protection. Received: 29 July 1996 / Revision received: 15 November 1996 / Accepted: 8 December 1996  相似文献   

9.
作者已经报导了利用卷蛾翅脉作为种类鉴定的可行性。本文具体介绍用翅脉鉴定种类的专家系统里的三个关键性技术要点。它们是:在翅脉交点坐标系确立问题上,创立了“二中心法”;在翅脉图像输入时,发明了“模型对位法”;最后,在输出鉴定结果时,又提出了“类似度排序法”。  相似文献   

10.
Abstract  The author has reported the possibility to use venation for identification of tortricids. In the previous paper (Liu 1996), an expert system for identification using venation was also described. The present paper introduces the technique how to construct the expert system. Three original solutions in the research are published. They are: establishment of corrdinates of venation—"two-centre method", the interface to accept inputs—"model modification method" and the interface to generate outputs—"sequence method".  相似文献   

11.
The dicot genus Flaveria (Asteraceae), besides species with C3 or C4 photosynthesis, contains taxa with a broad range of different states of transition between the two major photosynthetic types. We have developed a reproducible and efficient Agrobacterium-mediated method for the stable genetic transformation of the C3–C4 intermediate species F. pubescens. Fusion constructs of the reporter gene β-glucuronidase (uidA, GUS) to several plant promoters, mainly derived from genes encoding subunits of the glycine cleavage system (gdcs), have been used to confirm the reproducibility and efficiency of the method. The stable integration of the foreign DNA has been examined by Southern analysis, kanamycin resistance, GUS enzyme activities and histochemical staining. Transformed shoots can be routinely obtained within 8–10 weeks after co-cultivation with A. tumefaciens. Received: 16 April 1996 / Revision received: 12 July 1996 / Accepted: 28 July 1996  相似文献   

12.
Abstract Wireworms (Coleoptera: Elateridae) damage the eyes and young shoots of germinating cane setts in many growing regions. Insecticides can be applied at planting to avoid damage. However, there are no guidelines for deciding on whether treatment is warranted and a sampling method to detect wireworms before planting has not been developed. Baits of rolled oats were tested as a method for detecting wireworms in preplant fallows. In 1995 at Bundaberg, the reduction in crop establishment when treatment was withheld was positively correlated with the catch of wireworms at baits before planting. However, no similar relationship was seen in 1996 or at Mackay in either 1995 or 1996: severe damage was recorded on one farm at Mackay where no wireworms had been found. A sampling plan was developed to estimate wireworm numbers at baits with a fixed level of precision. Wireworms collected at the baits and in samples from established canefields in Queensland and New South Wales included five named and 21 unnamed species from five genera, the most abundant being Agrypnus , Conoderus and Heteroderes . Possible barriers to the adoption of baiting as a decision-support tool are discussed. Development of a reliable monitoring system would require considerably more research, which could not be justified at present.  相似文献   

13.
Rapid detection of trisomy 21 by homologous gene quantitative PCR (HGQ-PCR)   总被引:21,自引:0,他引:21  
Down’s syndrome results from the production of three copies of chromosome 21 within a cell. We have devised a method termed the homologous gene quantitative polymerase chain reaction (HGQ-PCR), which uses one pair of primers and which can directly identify the additional copy of chromosome 21 by simultaneously amplifying two highly homologous genes of the human liver-type phosphofructokinase located on chromosome 21 (PFKL-CH21) and the human muscle-type phosphofructokinase located on chromosome 1 (PFKM-CH1) for self-detecting determination. On analysis of 34 cases of Down’s syndrome, including two cases of unbalanced translocation 46, XY, der (14; 21) (q10; q10), + 21, and 100 normal individuals, the relative ratio of the PFKM-CH1/PFKL-CH21 product was 1.33 ± 0.323 (mean ± SD) and 0.40 ± 0.16 (mean ± SD) for disomy DNA and trisomy DNA, respectively. The difference between these two groups was highly significant (P < 0.001). These results indicate that this quantitative method is practical and may be used for the prenatal diagnosis of Down’s syndrome caused by trisomy 21. Received: 24 June 1996 / Revised: 18 September 1996  相似文献   

14.
The morphology of the mature spermatozoa of the closely-relatedfreshwater pulmonates, Bulinus africanus and Bulinus globosus,was examined using scanning and transmission electron microscopy.A comparison showed no useful differences that could be usedto distinguish the species though they did differ in one respectfrom Bulinus tropicus, the only other bulinid for which spermmorphology is known. (Received 12 August 1996; accepted 6 December 1996)  相似文献   

15.
A novel approach is proposed toward quantifying changes in chaetotaxy during the development of Collembola Symphypleona. The ontogenetic trajectories method applied to the tibiotarsal chaetotaxy of Symphypleona provides a representation of their development. Every seta, through the probability of its presence, can be regarded as a character. The statistical technique of correspondence analysis is used, and new techniques for analyzing these kinds of data are discussed. Although this survey is mainly focused on methodology, biological results are also presented. The different rates and extent of chaetotaxic changes during development of the species studied are discussed. An important point demonstrated is the support this method gives to the close relationship of Mackenziella and Sminthurididae. The assumption of monophyly of the group Sminthuridae-Bourletiellidae is also reinforced, and a hypothesis of neochaetotic evolution for the genus Sminthurus is put forward. © 1996 Wiley-Liss, Inc.  相似文献   

16.
The reverse micellar system of sodium bis(2-ethylhexyl) phosphate (NaDEHP)/isooctane/brine was used for liquid-liquid extraction of proteins. We investigated the solubilization of cytochrome-c and alpha-chymotrypsin into the NaDEHP reverse micellar phase by varying the pH and NaCl concentration in the aqueous phase. At neutral pH and relatively low ionic strength, the proteins are extracted into the micellar phase with high yield. By contacting the micellar phase with a divalent cation (e.g., Ca(2+)) aqueous solution, the reverse micelles are destabilized and release the protein molecules back into an aqueous solution for recovery. This method separates the proteins from the surfactant with very high overall efficiencies. (c) 1996 John Wiley & Sons, Inc.  相似文献   

17.
When assaying for sequence heterogeneity within monomorphic RAPD-PCR products in grapevines (Vitis spp.), we observed partial digestibility of a marker with the restriction enzyme MspI. The degree of digestion varied reproducibly between different cultivars. To study this phenomenon, two of the amplification products were cloned and sequenced. They show 91.7% similarity to each other. The DNA analysed was found to possess high similarity to retrotransposons from higher plants. This element seems repetitive and dispersed throughout the genome. To our knowledge, this is the first report of retrotransposon-like elements in woody plants. Received: 15 August 1996 / Revision received: 7 October 1996 / Accepted: 20 October 1996  相似文献   

18.
《新西兰生态学杂志》2011,23(1):101-103
The longevity of common geckos (Hoplodactylus maculatus) on predator-free Motunau Island, North Canterbury, was investigated. Sixteen of 133 individuals marked between 1967-75 were re-captured in the summer of 1996/97. A growth curve was generated to estimate the age of these geckos at first capture, and from this their age in 1996/97; 10 were estimated to be at least 36 years old. In this cool-temperate habitat, H. maculatus matures late and has a low annual reproductive output over an extended lifespan. This suggests that nearby mainland populations would be particularly slow to recover from the impacts of introduced mammalian predators.  相似文献   

19.
Comparison of freshly collected tetraphyllidean cestodes from a teleost fish, Alepisaurus ferox Lowe, from Japan with types and vouchers of Pelichnibothrium speciosum Monticelli, 1889, described from the same host, and specimens of Prionacestus bipartitus Mete & Euzet, 1996, from the spiral valve of a shark, Prionace glauca (Linnaeus), from the Indian Ocean between Réunion and Madagascar, revealed their conspecificity. Consequently, P. bipartitus is considered a junior synonym of P. speciosum and the genus Prionacestus Mete & Euzet, 1996 is suppressed. The life-cycle of the parasite, which retains larval features and is considered to represent a neotenic form, is discussed.  相似文献   

20.
Variation in the effectiveness of biocontrol agents on the weed Parthenium hysterophorus L. was evaluated at two properties (Mount Panorama and Plain Creek) in Queensland, Australia for four years (1996-2000) using a pesticide exclusion experiment. At Mount Panorama, higher levels of defoliation by the leaf-feeding beetle Zygogramma bicolorata Pallister and galling by the moth Epiblema strenuana Walker in 1996-97 coincided with an above average summer rainfall, but in the following three years with below average summer rainfall the defoliation and galling levels were significantly lower. Biocontrol had significant negative impact on the weed only in 1996-97 with no major impact in the following three years. At Plain Creek, galling by E. strenuana was evident in all the four years, but varied significantly between years due to non-synchrony between P. hysterophorus germination and E. strenuana emergence. At Plain Creek biocontrol had limited impact on the weed in 1996-97 and 1997-98, with no significant impact in the following two years. Over the 4-year period, defoliation and galling resulted in 70% reduction in the soil seed bank at Mount Panorama, but the reduction in the soil seed bank at Plain Creek due to galling was not significant. Effectiveness of Z. bicolorata and E. strenuana was dependent on weather conditions and as a result had only limited impact on the weed in three out of four years.  相似文献   

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