野生黄精的多糖含量测定及提取工艺研究

采用3,5-二硝基水杨酸法(DNS法)测定了宁波四明山区野生黄精的多糖含量,并对水煎煮法提取黄精多糖的工艺进行优化。通过单因素实验获得了提取温度、提取时间、液料比对黄精多糖得率的影响;在单因素实验的基础上采用L_9(3~4)正交试验优化黄精多糖提取工艺。研究结果表明,宁波野生黄精多糖的含量为25.09%;各因素对黄精多糖得率的影响不同,液料比对黄精多糖得率的影响最大,其次是提取温度和提取时间。黄精多糖最佳提取工艺为:提取温度为80℃,提取时间为2 h,液料比为20∶1,在该条件下,黄精多糖得率为27.43%。为黄精多糖的开发利用奠定了理论基础。     

变色疣柄牛肝菌子实体水溶性粗多糖的提取方法

试验就变色疣柄牛肝菌多糖的提取方法进行了初浅探索,结果表明变色疣柄牛肝菌干燥子实体萃取粗多糖较佳的条件为:粒度以粉碎60目筛、提取剂为蒸馏水、选择菌盖、选择料水比为1∶35(W/V)、沉淀剂达到85%的乙醇浓度、萃取温度选择在80℃、萃取时间为3 h、提取2次可得到粗多糖3%~5%。正交试验表明影响变色疣柄牛肝菌多糖得率的主次因素为乙醇浓度、提取温度、提取时间、料水比,各因素的最佳配合、最优工艺为A3B2C1D3,即乙醇浓度为85%、温度80℃、时间3 h、料水比为1∶15,在此条件下多糖得率为5.008%,提取粗多糖含量在47.995%。     

均匀设计法优化高丽参多糖的提取

利用均匀设计法优化了高丽参多糖的提取过程.主要考察料液质量比、浸泡时间、提取温度和提取时间四个因素对提取率的影响.通过数学模型得到最优提取状况和3D曲面图.结果表明,提取温度对高丽参多糖得率影响最大,在料液质量比1:35、浸泡时间135 min、水提取温度81℃条件下提取156 min,高丽参多糖最大理论提取率为49.51%.最优化模型下实际多糖得率49.29%与理论得率相符.     

响应面法优化胡芦巴种子多糖提取工艺

利用单因素实验及响应面法优化确定胡芦巴种子多糖的提取工艺。通过单因素实验筛选出料液比、提取时间、提取温度三个主要因素,以胡芦巴种子多糖提取得率为响应值进行Box-Behnken中心组合试验设计,建立胡芦巴种子多糖提取得率的二次回归方程,得到优化组合条件。响应面法分析结果表明,当料液比为1∶28(g:mL),提取时间1.2 h,提取温度85℃时验证优化工艺得胡芦巴种子多糖最大提取得率19.89%,接近于模型预测值20.24%。     

牛樟芝固态发酵菌丝体三萜及多糖提取工艺优化研究

为研究牛樟芝固态发酵菌丝体中三萜和多糖的最佳提取工艺，选取浸提时间、料液比和提取温度3个因素，分别设置3个水平，以三萜和多糖得率为指标，并采用正交试验法进行分析。结果表明，三萜的最佳提取工艺条件为：浸提时间3 h、料液比1∶30 (g·mL-1)、温度70 ℃，在此条件下，得率为3.43%；多糖的最佳提取工艺为：浸提时间2 h、料液比1∶20 (g·mL-1)、温度95 ℃，在此条件下得率为4.71%。研究结果为牛樟芝固态发酵菌丝体中三萜和多糖的提取工艺提供了参考。     

正交试验法优化桑叶多糖提取工艺

以脱除黄酮的桑叶为原料,采用热水浸提法提取桑叶多糖,研究了提取温度、提取时间、料液比、水溶液pH和提取次数对桑叶多糖得率的影响,通过正交实验优化了提取工艺条件。结果表明,在提取次数为2次条件下,桑叶多糖最佳提取工艺条件为提取温度100℃、提取时间4 h、提取液pH7、料液比(原料:提取液,g/mL)1:30,多糖得率为2.74%。该工艺稳定,桑叶多糖得率高,易于工业化生产。     

枸杞色素及多糖的不同提取次序对其得率及抗氧化活性的影响

为探究先后提取枸杞多糖及枸杞色素时对各自得率的影响。本研究通过分别考察这两种成分在提取过程中的提取溶剂、提取温度、料液比、提取次数及提取时间等因素对枸杞色素和枸杞多糖的得率影响,确定枸杞色素和枸杞多糖在提取次序不同时,两者的最佳提取工艺以及对DPPH·和·OH自由基清除率。结果表明,首先提取枸杞多糖后,枸杞色素的最佳提取工艺为采用正己烷,80℃时,料液比1∶10,提取2次,每次1 h,枸杞色素得率为2.48%,此时枸杞多糖得率为7.45%;而首先提取枸杞色素后,采用了超声辅助提取的方式提取枸杞多糖,发现超声效率为25%,料液比1∶10,提取20 min,枸杞多糖得率为5.23%,此时枸杞色素得率为3.93%。因此,首先提取枸杞多糖,使其平均得率为7.45%,而后提取枸杞色素,其平均得率为2.48%;总体上,枸杞色素1和枸杞多糖1对DPPH·自由基清除率都较高,枸杞多糖1对·OH自由基清除率较高,其抗氧化活性都接近Vc。     

响应面法优化香菇多糖的超声辅助提取工艺

为了开发利用香菇资源,采用超声辅助法提取香菇中的多糖,利用响应面法优化超声辅助提取法提取香菇多糖的工艺条件。首先进行单因素试验考察,在单因素试验的基础上,选择超声波功率、超声时间及料液比为自变量,以多糖得率为响应值,采用Box-Benhnken法设计3因素3水平响应面设计试验。结果表明,响应面模型与实际情况拟合良好,能较好地预测香菇多糖得率。最佳工艺:超声波功率300 W、超声波处理时间25 min、料液比1∶30,多糖得率25.71%,与理论值(25.55%)相比,相对误差较小,为0.63%。与传统热水浸提法比较,超声波提取法多糖得率较高,且耗时少,是理想的香菇多糖提取方法。     

正交实验法优化极长钝顶螺旋藻多糖提取分离条件研究

目的:为研究螺旋藻最佳提取条件.方法:采用单因次试验和正交试验法考察提取时间、次数、温度和乙醇浓度对于多糖提取的影响.结果:确定了螺旋藻多糖的最佳提取工艺是温度80℃、时间3 h、提取次数2次和乙醇浓度为75%.结论:发现温度显著影响多糖提取率,而高浓度乙醇能提高得率.     

响应面分析法优化超声波辅助酶法提取南五味子多糖工艺的研究

为了建立超声波辅助酶法提取南五味子多糖的方法,并研究其提取工艺。按照Box-Benhnken中心组合试验设计原理,以多糖得率为响应值,以单因素实验数据为基础,进行响应面分析实验,考察提取pH、提取温度和提取时间对多糖得率的影响。结果显示：最佳提取工艺条件为：提取pH为4.8、提取温度57℃、提取时间66 min、复合酶用量为3.0%,最佳工艺条件下南五味子多糖得率为8.73%±0.25%。研究结果表明,该提取方法可减少多糖提取时间和提取溶剂用量,降低温度,有效提高了多糖的提取得率,可应用于南五味子多糖的制备。研究结果为南五味子多糖的开发应用提供了较好的依据。     

Ectogenesis and the case against the right to the death of the foetus

Ectogenesis, or the use of an artificial womb to allow a foetus to develop, will likely become a reality within a few decades, and could significantly affect the abortion debate. We first examine the implications for Judith Jarvis Thomson’s violinist analogy, which argues for a woman’s right to withdraw life support from the foetus and so terminate her pregnancy, even if the foetus is granted full moral status. We show that on Thomson’s reasoning, there is no right to the death of the foetus, and abortion is not permissible if ectogenesis is available, provided it is safe and inexpensive. This raises the question of whether there are persuasive reasons for the right to the death of the foetus that could be exercised in the context of ectogenesis. Eric Mathison and Jeremy Davis have examined several arguments for this right, doubting that it exists, while Joona Räsänen has recently criticized their reasoning. We respond to Räsänen’s analysis, concluding that his arguments are unsuccessful, and that there is no right to the death of the foetus in these circumstances.     

On the diversity of the Cladocera in the tropics

The mythical concept of an impoverished tropical cladoceran fauna is refuted. On a planetary scale, around half of the cladoceran species presently known occur exclusively in the tropics-subtropics, often with considerable restriction to particular geographical subzones. On a regional (political) scale, the situation is often unclear because of the continued fragmentary nature of studies, and because political units are not a good basis for biogeographical comparisons. At the finest level of resolution (lake-perlake comparisons), there appears to be an upper limit of c. 50 cladoceran species per individual lake. No significant difference between lakes in the temperate zone and in the tropics could be established here. Daphnia is largely absent from the tropics, but is replaced by more Sidids, Moinids, and Bosminids, such that the average cladoceran community in the limnetic zone of a tropical lake is not characterized by less species but rather by lower population densities. This, in turn, is considered a consequence of higher prevalent predation levels in the tropics.     

Tubular networks in the terminal endings of the visual receptor cells in the human,the monkey,the cat and the dog

Summary A tubular network was found in the terminal endings of the visual receptor cells in the human, the monkey (Macaca mulatta), the cat and the dog. These tubules are arranged in close groups in the vicinity of the synaptic lamellae and the invaginated dendrites. According to the form, diameter, density of the tubules and to the consistence of the network formed by them one can distinguish at these places an initial type (type I), a transitory (type II) and a vesicular one (type III). In the the type III branching, bizarre forms are frequent. The diameter of all the tubules reaches 500–600 Å, their density and walls being the same as in the synaptic vesicles.Similar networks also occur in the axons of the visual receptor cells of the monkey.

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Zusammenfassung In den Endigungen der Photorezeptorzellen von Mensch, Affe (Macaca mulatta), Katze und Hund kommen aus Tubuli bestehende Komplexe vor. Organellenartig in geschlossenen Gruppen angeordnet, liegen sie in Nähe der synaptischen Lamellen und der invaginierten Dendriten. An diesen Stellen kann man nach Form, Durchmesser, Dichte und Konsistenz der von den Tubuli gebildeten Komplexe drei Typen unterscheiden: 1. einen initialen (Typus I), 2. einen Übergangstypus (Typus II) und 3. einen vesiculären Typus (Typus III). In letzterem kommen häufig verzweigte, bizarre Formen vor. Der Durchmesser sämtlicher Tubuli erreicht 500–600 Å. Ihre Dichte und ihre Wand gleicht denen der synaptischen Vesikel.Ähnliche Komplexe fanden wir auch in den Axonen der Photorezeptorzellen vom Affen.

     

Assessing the Physiological State of the Fucoids from the Barents Sea Littoral by the End of the Polar Night

Methods of amperometry and potentiometric titration were used to follow dark respiration (DR) and apparent photosynthesis (AP) in the fucoids Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea littoral by the end of the 40-day-long polar night. The macroalgae were shown to manifest species-specific low rates of photosynthesis and respiration. However, in spite of their low photosynthetic status due to the effects of subzero temperature and prolonged low or zero illumination, the macroalgae have been able to restore DR and AP to the initial level already by the day 9; the ability to restore AP depended on the level of illumination. The study of the changes in the carbonate–bicarbonate system in the light and darkness demonstrated that the macroalgae grown in darkness, in contrast to those grown in twilight, could absorb bicarbonate in darkness; however, they lost this capacity after two-day-long illumination at an irradiance of 7 mol/(m² s). Bicarbonate uptake in darkness and the capacity to restore the systems of photosynthesis and respiration in fucoid cells are discussed in the context of algal energy metabolism under the polar night conditions.     

Arranging the elements of the potassium channel: the T1 domain occludes the cytoplasmic face of the channel

The voltage-gated potassium channel is currently one of the few membrane proteins where functional roles have been mapped onto specific segments of sequence. Although high-resolution structures of the transmembrane portions of three bacterial potassium channels, the tetramerization domain and the cytoplasmic ball are available, their relative spatial arrangement in mammalian channels remains a matter of ongoing debate. Cryo-electron microscopic images of the six transmembrane voltage-gated Kv channel have been reconstructed at up to 18 Å resolution, revealing that the T1 domain tetramerizes and is suspended below the transmembrane segments. However, the resolution of these images is insufficient to reveal the location of the third piece of the puzzle, the inactivating ball domain. We have used the aberrant interactions observed in a series of chimæric channels to establish that an assembled T1 domain restricts access to the cytoplasmic face of the channel, suggesting that the N-terminal ball and chain may be confined in the space between the T1 domain and the transmembrane portion of the channel.     

Feeding the vertebrate retina from the Cambrian to the Tertiary

The retina of the vertebrate eye is metabolically active and requires nutritive support. During the last 540 million years it has evolved into forms as complicated and nutritionally demanding as those found in avian or primate eyes. Diffusion from the choroid is generally able to supply the metabolic needs of thin retinae. However, when the thickness exceeds the limits of diffusion, structures are needed to supplement the vascular supply from the choroid. These supplemental nutritive devices include the choroidal gland, the falciform process and preretinal vascular plexus of fish, the conus papillaris of lizards, the pecten oculi of birds, the intraretinal vessels of mammals and a few novel systems that remain difficult to classify. These vascular systems are among the most variable features of the vertebrate eye. Here, we review classical and recent findings regarding such retinal nutrition systems, propose a three category classification for them based on histologic origins and speculate on the evolutionary forces which drove their development.     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418     

Separation of the pineal vesicle from the wall of the third ventricle during the post-hatching development of the chicken

Summary According to light- and electron-microscopic observations the pineal organ of the 3-day-old chicken consists of a prominent end vesicle and a tapering parenchymal stalk. During this stage the pineal lumen is in open communication with the third ventricle. However, in the 40-day-old chicken, which still possesses a well-developed end vesicle, the proximal portion of the pineal stalk displays regressive changes leading to local fragmentation. At this stage the pineal stalk is reduced, and the pineal lumen is missing. In 1-year-old chickens the parenchyma of the proximal portion of the stalk is further diminished, and in 3-year-old domestic fowl is completely displaced by bundles of collagenous fibers, only some nerve fibers being present. This post-hatching pineal development may reflect the sequence of changes leading from pineal sense organs to pineal glands.This work was supported by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan