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101.
102.
Cryopreservation is the most promising option for the long-term germplasm conservation of recalcitrant-seeded species. However, the variable post-cryo success achieved with the excised zygotic explants traditionally used for cryopreservation has been a concern for some time. Differential drying rates amongst explants of different species, uneven drying amongst explants within a batch of seeds and uneven drying across tissues within individual embryos could be contributory factors to this variable success and these phenomena form the foci of the present study. Using zygotic explants from a range of recalcitrant-seeded species, which included sub-tropical dicotyledonous trees and sub-tropical monocotyledonous geophytes, the study showed that embryo morphology and anatomy are critical determinants of the drying characteristics of the different tissues composing the explant and hence, post-cryo survival. The results suggest that the rates of drying of explants to water contents (WCs) in the theoretically optimal range for successful cryopreservation are species-specific, and that more rapid drying rates may promote post-cryo survival. However, the large variation in WC amongst individual explants in bulk samples challenges the selection of the theoretically optimum WC for cryopreservation. As a consequence of differential drying rates across the different tissues composing explants, either lethal ice crystal damage or desiccation damage may sometimes be likely in tissues responsible for the onwards development of the embryo. Drying times for cryopreservation of such explants should, therefore, be selected on the basis of WC of segments containing root or shoot meristem, rather than embryo bulk WC. Drying intensity and duration also interact with explant morphology and embryo/axis size and anatomy to bring about – or preclude – post-cryo survival. 相似文献
103.
The external mycelium forms the major part of the absorbing surface of mycorrhized tree roots. Because the macro pore space of acid forest soils is selectively depleted of mobile nutrient cations, it is ecologically important, whether soil hyphae grow into the soil aggregates or not. Seedlings of Norway Spruce (Picea abies (L.) Karst.) with defined mycorrhiza were grown in unsterilized soil cores taken from the A and B-horizon of a limed and an unlimed cambisol on triassic sandstone in the Northern Black Forest, Germany. Water-tension treatments were 10, 30, 160 and 900 hPa. On ground and polished vertical cuts stained with acridine orange, we identified and measured the location of hyphae and characterized their micropedological environment using an image analyzing system. Mean length density varied between 17 m/cm3 and 100 m/cm3 and was independent of aeration parameters. The percentage of hyphae completely embedded in the soil matrix varied between 30% and 8% and decreased significantly with increasing CO2 concentration in the soil air. Of the hyphae in the soil matrix, 70% were located in a 50 m shell around the macro pores. Pair correlation functions show, that the majority of soil hyphae occur in clusters with diameters below 100 m. Between 60% and 80% of randomly chosen circles with 250 m diameters were completely devoid of hyphae. The inefficient opening up of the intra-aggregate space by soil hyphae is explained by the very slow oxygen diffusion between air-filled macro pores and the intra-aggregate space and mechanical restrictions for hyphae growth. 相似文献
104.
中药王不留行化学成分的研究Ⅲ 总被引:3,自引:0,他引:3
从经产麦蓝菜(Vaccaria segetalis(Neck)Garche.)的种子王不留行中分离得到5个化合物,经波谱分析和化学方法分别鉴定为化学方法分别鉴定为:VaccarosideB(1)、C(2)、D、(3),6-N-methyladenosine(4)和N,N-dimethyl-L-tryptophan(5)。其中化合物4和5为首次从该植物中分得。 相似文献
105.
106.
1996~1997在芸豆(云南)、红小豆(河北)、大豆(黑龙江)和花生(山东)绿色食品产地,研究了施用有机肥和化肥对这些作物籽粒中NO3-、NO2-的累积特点.结果表明,芸豆和红小豆不论施用有机肥还是尿素,土壤中的速效氮与籽粒中NO2-的灰色关联最好;施用有机肥的最大关联度分别出现在土壤库内部(全氮与速效氮之间)或籽粒库内部(NO3-、NO2-之间);而施用化肥的最大关联度分别出现在土壤库与籽粒库的全氮与NO3-之间.芸豆和红小豆随着施肥水平的提高,籽粒中NO3-/NO2-比值动态变化趋势因施用有机肥和施用化肥而不同.这4类作物籽粒中的NO3-与NO2-存在着极显著的负直线相关关系和极显著的直线回归关系. 相似文献
107.
108.
1996~1997在芸豆(云南)、红小豆(河北)、大豆(黑龙江)和花生(山东)绿色食品产地,研究了施用有机肥和化肥对这些作物籽粒中NO-3、NO-2的累积特点.结果表明,芸豆和红小豆不论施用有机肥还是尿素,土壤中的速效氮与籽粒中NO-2的灰色关联最好;施用有机肥的最大关联度分别出现在土壤库内部(全氮与速效氮之间)或籽粒库内部(NO-3、NO-2之间);而施用化肥的最大关联度分别出现在土壤库与籽粒库的全氮与NO-3之间.芸豆和红小豆随着施肥水平的提高,籽粒中NO-3/NO-2比值动态变化趋势因施用有机肥和施用化肥而不同.这4类作物籽粒中的NO-3与NO-2存在着极显著的负直线相关关系和极显著的直线回归关系 相似文献
109.
Extraction of high-quality RNA from Arabidopsis seeds has been a challenge. Here we report a two-step TRIzol-based procedure for RNA extraction from Arabidopsis siliques and dry seeds. This procedure employs a modified, high pH (pH 9.5) extraction buffer. High pH plus the addition of either DTT or β-mercaptoethanol in the extraction buffer effectively inhibits RNase activity during the extraction, and removes most polysaccharides, polyphenols and other insoluble material. TRIzol reagent was subsequently used to purify the RNA. Using this procedure we isolated high-quality DNA-free RNA samples without DNase I treatment from Arabidopsis seeds or siliques in less than 3 h. 相似文献
110.
Juan I. Urcola Cesar J. Benetti Yves Alarie Georgina Rodriguez Mariano C. Michat 《Journal of morphology》2020,281(10):1210-1222
Larvae of the burrowing water beetle family Noteridae are distributed worldwide and are often abundant in a broad range of aquatic habitats, playing an important role in structuring freshwater communities, yet they have remained among the most poorly studied groups of aquatic beetles. Studies on sensillar equipment of aquatic insect larvae are largely lacking, despite their potential use in phylogeny and biometric identification methods. In this article, the external morphology and distribution of sensilla on the head appendages of first instar larvae of selected genera of Noteridae were examined using scanning electron microscopy. Seven main types were distinguished based on their morphological structure: basiconica (3 subtypes), campaniformia (2 subtypes), chaetica (7 subtypes), coeloconica (6 subtypes), coniform complex (2 subtypes), placodea, and styloconica (3 subtypes). The apex of the labial palpus was found to be the most variable and informative region in regard to the number, relative position, and topology of sensilla. Fingerprint models were, therefore, generated for this region in each of the studied genera, allowing their identification. 相似文献