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 625 毫秒
1.
Two cassava cultivars were fermented for 3 days with the incorporation of soybean residue or full-fat flour at 25% (w/w) to produce gari. Unfortified gari was superior in taste (P<0.05) to the soybean-fortified gari, though consumers still accepted the latter. Fortified samples from two of the three procedures used, in which soybean was added at different stages of the fermentation, were rated similarly (P>0.05). The water activity of soybean-fortified gari was <0.7, the swelling capacity was 2.5 to 3.3, pH was 5.1±0.2 and total cyanide was 0.8 to 1.3 mg/100 g. The crude protein content of soybean-fortified gari was 8 to 12% (w/w), much higher than the 1 to 2% (w/w) of the unfortified gari. Soybean-fortified gari is recommended for use in areas where cassava is consumed and protein intake is inadequate.The authors are with the Biology Department, The Polytechnic, Ibadan, Nigeria.  相似文献   

2.
Activities and characteristics of transfer factors   总被引:2,自引:0,他引:2  
This report summarizes three components of our transfer factor research program. Several clinical studies have used oral administration of transfer factor containing materials. Sceptics have rejected these findings by assuming that the acidic and enzymatic environment of the gastrointestinal tract would destroy the factors. To further examine this issue, we have conducted dose-response studies of the delayed-type hypersensitivity reaction in mice that were given transfer factor either by gavage or subcutaneously. There were no difference in the responses that were related to the route of administration. We conclude that oral route of administration is efficacious and should be used when possible. We have also studied the effects of transfer factors on immune responses by recipients. The details of this research are presented in the paper by Dr. Alvarez-Thull. Briefly, the study showed that recipients of a specific transfer factor responded to the antigen for which the factor was specific by secreting gamma-IFN, but no other cytokines. The structures of transfer factor molecules are unknown. We have developed a process for isolating transfer factors in pure form and we have obtained preliminary data concerning amino acid sequences. Our goal is to obtain the complete primary structure of several transfer factor molecules.  相似文献   

3.
A survey of the molecular features of microsporidia is presented which attempts to comment on unresolved questions concerning the physiology of these amitochondrial intracellular parasites. Various transports of host-derived molecules can be predicted and trehalose appears as a potential reserve of glucose for energy metabolism. Significant insights into membrane lipids, polyamine metabolism and sporogony-specific proteins have been gained. Some species, such as Encephalitozoon cuniculi, are heterogeneous entities and harbor a small genome. Although showing a variation in genome size of 8.5-fold, microsporidia share reduced rDNA genes. Finally, data on gene organization and a possible evolutionary relationship with fungi are considered.  相似文献   

4.
A method for isolation of staphylococcal alpha-toxin preparations has been elaborated. Characteristics of the toxin isolated by the method are as follows: mol. mass = 35 Kd; HU = 0.1 microgram; DnD= 0.1 microgram; LD50 = 2 micrograms. It is for the first time that alpha-toxin was fragmented by papain and digested by alpha, gamma-chemotrypsin. The papain fragments (18.5 and 15 Kd) retained lethal activity but lost hemolytic and dermonecrotic activities. Alpha, gamma-chemotryptic digested fragments (18 and 15 Kd) retained hemolytic and lethal effects, but lost their dermonecrotic activity.  相似文献   

5.
Urea-triazone nitrogen (N) is a stable solution resulting from a controlled reaction in aqueous medium of urea, formaldehyde, and ammonia which contains at least 25% total N. This N source contains no more than 40%, nor less than 5%, of total N from unreacted urea and not less that 40% from triazone. All other N shall be derived from water-soluble dissolved reaction products of the above reactants. It is a source of slowly available N. The rate of mineralization of urea-triazone is about 66% that of urea after 8 days when incorporated in a Munjor sandy loam. Ammonia volatilization losses of N applied as urea-triazone were about 41% of those from urea on a Cecil sandy loam in the first week after application. N leaching losses through saturated Yolo loam columns of urea-triazone were about two thirds that of urea or nitrate N. This N source has proven to be a safer and more effective material for direct application on plant foliage. Tomato growth was enhanced with foliar application of urea-triazone relative to that obtained from ammonium nitrate or urea. The stability of this N source from potential losses via ammonia volatilization and nitrate leaching when soil applied is also documented by results from university trials.  相似文献   

6.
Asexual reproduction (fissioning) in planarians is controlled by group size; increased group size suppresses fissioning, isolation releases it. This effect is mediated through the brain; social stimulation from cohorts causes the brain to inhibit the segmental plexus fissioning system from initiating the events of fissioning. Experiments were conducted to elucidate (1) the stimulus cue conveying information regarding cohort number and (2) the switching characteristics of the control system. The results of these show that the social stimulus responsible for the effect involves neither vision nor discharge of pheromonal substances into the habitat; the sensory event apparently involves direct contact and chemoreceptive, as well as tactile, modalities. The switching characteristics (graduated response, long release time, short reinstatement time) found for the brain inhibitory system agree with those expected from the mathematical model derived for a simple neurohormonal control system in which it is postulated that social stimulation causes neurosecretory cells of the brain to release a fissioning inhibitory hormone (FIH) that inhibits the segmental plexus fissioning (SPF) system from initiating fissioning.  相似文献   

7.
Summary As determined by electron microscopy, lipid sonicated in buffer initially forms large vesicles which may be multilamellar. Prolonged sonication results in a population of vesicles of smaller, but not uniform diameters. These vesicles are bounded by only one bilayer. The lipid suspension can be partially fractionated according to size by column chromatography. A fraction of the eluate has been selected for further study. The weight-average vesicle weight and average radius of gyration are obtained by lightscattering measurements. The volume of buffer enclosed by the vesicles is determined using14C- or3H-labelled sugars as a marker. These values are in reasonable agreement with the corresponding values calculated from the size distribution of the vesicle fraction obtained by electron microscopy.  相似文献   

8.
Stigma characteristics and angiosperm taxonomy   总被引:1,自引:0,他引:1  
When a classification based upon certain morphological and physiological characters of the stigma was applied to ca. 1,000 species of some 900 genera of angiosperms, several taxonomic regularities emerged. Most families proved to be relatively homogeneous in stigma type, whilst others were strikingly diverse. Among the latter were certain supposedly primitive families such as the Liliaceae, a fact that may have some phylogenetical significance. Sometimes where a family proved to be homogeneous in respect to the more general characters of the stigma, fuller investigation revealed great variation in detail. An example is given by the Boraginaceae, a family in which stigma characters are of potential taxonomic importance. The stigma papillae in this family are often capitate, with heavily cutinised heads, and pollen has to be inserted forcibly between the papillae. There is a strong correlation between pollen size and stigma–papilla size, so that certain types of cross pollination are impossible. These specialisations can thus play a part as isolating mechanisms. The form of the stigma papillae is probably also important in genera of the Boraginaceae adapted to arid conditions, since the contiguous cutinised caps overarch the actual receptive surfaces and so. presumably, offer protection from desiccation.
In both monocotyledons and dicotyledons, clear relationships exist between stigma type and physiology, and notably with the type of self–incompatibility system. It is already apparent that stigma characters can have predictive value in the investigation of breeding systems.
The paper includes a comprehensive literature list, covering most ot the principal sources of structural, taxonomic and other data bearing upon angiosperm stigmas.  相似文献   

9.
银杏超小卷叶蛾生物学特性与防治   总被引:2,自引:0,他引:2  
余桂萍  高帮年 《昆虫知识》2004,41(5):475-477
银杏超小卷叶蛾PammeneginkgoicolaLiu在安徽黄山、九华山 1年发生 1代 ,以蛹在粗树皮内或树枝裂缝中越冬。该虫以幼虫蛀食短枝和当年生长枝嫩茎 ,翌年 4月上旬为成虫羽化期 ,4月上旬至 5月上旬达羽化高峰。 4月中旬为产卵盛期 ,4月上旬幼虫孵化 ,4月下旬孵化盛期 ,4月上旬至 5月底为幼虫为害期 ,5月下旬至 7月上旬幼虫全部钻入树皮。 5月份用 2 5 %溴氰菊酯乳油 3 0 0 0倍喷雾或用80 %敌敌畏 1 0 0 0倍液与 40 %氧化乐果 1 0 0 0倍液混合喷雾 ,防治效果 90 %左右。 6月中下旬用敌敌畏原液、氧化乐果、柴油按 1∶1 5∶3的比配成油雾剂喷洒树干 ,可有效地消灭害虫。  相似文献   

10.
The reproductive biology of Type 3 reducing-system bivalves (those whose pallial cavity is irrigated with water rich in reducing substances) is reviewed, with respect to size-at-maturity, sexuality, reproductive cycle, gamete size, symbiont transmission, and larval development/dispersal strategies. The pattern which emerges from the fragmentary data is that these organisms present reproductive particularities associated with their habitat, and with their degree of reliance on bacterial endosymbionts. A partial exception to this pattern is the genus Bathymodiolus, which also presents fewer trophic adaptations to the reducing environment, suggesting a bivalent adaptive strategy. A more complete understanding of the reproductive biology of Type 3 bivalves requires much more data, which may not be feasible for some aspects in the deep-sea species.  相似文献   

11.
Synopsis Structure and function of the digestive system and feeding characteristics of the chondrosteans are reviewed. Although the group exhibits a wide diversity of feeding habits including piscivory, benthophagy, and planktivory, they are principally carnivores throughout their life history. Examination of digestive system structure reveals the basic structure to be similar among the species with some modification to accomodate the different food types. For the species studied, composition of the adult digestive enzyme complement is consistent with the carnivorous habits with proteases dominating and only low levels of carbohydrase activity. There are three secretory phases during development of the digestive system. Each corresponds with different food habits of the different life-history intervals. Vision is apparently not utilized for feeding in any interval. Instead food is recognized and located primarily by gustation, olfaction, textural qualities, and, possibly, electroreception.  相似文献   

12.
HeLa 71 and 65 cells grown in attached culture possess a coat of extracellular proteins that can be released from the cell by mild EDTA-detachment, with no significant effect on cellular integrity. This suggests that these surface proteins are weakly associated with the cell, possibly through divalent cations. The high affinity of surface proteins for critical divalent cations, shown by their high precipitability by Zn2+, Ca2+ and Mg2+, supports this assumption. Since surface proteins appear to be phosphoproteins, as suggested by significant incorporation of 32Pi in vitro, it is possible that binding occurs through The amount of surface protein on HeLa 65 cells grown in suspension culture is greatly reduced compared with cells grown in monolayer culture. This may be related to impaired availability of Ca2+ in suspension culture medium. In monolayer grown HeLa cells surface proteins are predominantly distributed underneath the cells. The highest amount of these proteins is found on cells prior to growth initiation and steadily decreases as cells approach confluency. As shown by radioactive leucine protein labeling, surface proteins are primarily comprised of proteins synthesized within HeLa cells and released to the outer cell surface. The presence of serum proteins in surface protein matrix is physiologically significant.  相似文献   

13.
Pasteurellosis, caused by Pasteurella piscicida, is one of the most threatening diseases of wild and cultured marine fish, and has been reported from many geographical areas including the USA, Japan and the Mediterranean countries. The objective of this article is to construct a picture of the current state of knowledge about this bacterial pathogen and the pathogenesis of the disease it causes. We review some important questions such as the controversial taxonomic position of the bacterium, and its main virulence mechanisms. The epidemiology of the disease, the routes of transmission and the putative reservoirs of P. piscicida in the environment are also discussed. Finally, a detailed survey of the strategies for controlling the disease is performed, including new diagnostic procedures, chemotherapy, employment of immunostimulants, and improvements in immunization programs.  相似文献   

14.
Psychophysical and behavioral characteristics of olfactory adaptation   总被引:1,自引:0,他引:1  
Dalton P 《Chemical senses》2000,25(4):487-492
Sensory adaptation allows organisms to reach behavioral equilibrium with the ambient environment and respond primarily to changes in stimulation. Given its functional significance, it is not surprising that adaptation in the olfactory system exhibits many of the same characteristics as adaptation in other sensory systems, including vision. Repeated or prolonged exposure to an odorant typically leads to stimulus-specific decreases in olfactory sensitivity to that odorant, but sensitivity recovers over time in the absence of further exposure. Psychophysical analysis shows that olfactory adaptation results in elevations in odor thresholds and in reduced responsiveness to suprathreshold stimulation. Further, the magnitude of the decrease and the time course of adaptation and recovery are dependent on the concentration of the odor and on the duration of exposure. It is generally agreed that olfactory adaptation can occur at multiple levels in the olfactory system and can involve both peripheral (receptor level) and more central (post-receptor) components. Evidence for peripheral and central involvement comes from studies showing that monorhinal stimulation results in adaptation in both the ipsilateral and contralateral nostril, although the degree of adaptation in the ipsilateral nostril is more profound and recovery is slower. Additional evidence for central involvement comes from studies that have found relatively small decreases in peripheral response following repeated stimulation despite substantial reductions in perceived intensity. Most psychophysical studies of adaptation, however, have not differentiated the peripheral and central processes. Although relatively few in number, studies of the parametric features of olfactory adaptation in both vertebrate (e.g. rat) and invertebrate (e.g. Drosophila, Caenorhabditis elegans) animal models appear to replicate the findings in psychophysical studies of adult humans. Despite the broad overall similarity of olfactory adaptation to adaptation in other sensory systems, olfactory adaptation exhibits some unique features. Adaptation in olfaction has been shown to be very long-lasting in some cases and may be modulated by the contribution of pre-neural events and physico-chemical properties of the odorant molecules that govern diffusion to receptor sites and post-receptor clearance.  相似文献   

15.
Craniofacial area is apart of the human body which undergoes the greatest changes during development and is characterized by uneven growth. External and internal factors affect the growth and development of craniofacial structures. They are responsible for the occurrence of specific craniofacial characteristics in different races or populations within the same race. The present study investigates the possible differences of the basic head and face shapes between the Croatian and Syrian populations. The sample included 400 subjects of both sexes aged 18-24 years and was divided into a Croatian and a Syrian group with 200 subjects each. Six variables defined according to Martin and Saller were measured by standard anthropometric instruments. The results of the study demonstrated statistically significant differences between our subjects in all variables except face width. The dolichocephalic head type and the mesoprosopic face type were predominant in the Croatian population, while the brachycephalic head type and the euryprosopic face type dominated in the Syrian population.  相似文献   

16.
17.
白网籽棕树形优美,老叶浓绿向下弯曲,新叶暗红,观赏效果颇佳。本文介绍西双版纳热带植物园引种的白网籽棕的形态特征、生物学特性、适应性及观赏利用价值。  相似文献   

18.
目前,中国人群头型、面型、鼻型、唇型、耳型尚未见大样本的资料报道。我们测量了中国115个族群的63449例头面部指标值,计算了头长宽指数等7项指数值,进行了指数与年龄的相关分析、年龄组间的方差分析,以及指数与纬度、年平均温度的相关分析。采用主成分分析方法研究了7个年龄组指数值。相关分析显示,随着年龄增长,中国人头型变得更长一些,更低一些;面变得更窄一些,鼻翼更宽一些,唇更薄些,耳变得更细长些。主成分分析结果也证实了这种规律。相关分析结果表明,随纬度的增大,中国人男性、女性头长宽指数、形态面指数值增大,鼻指数、容貌耳指数值减小。随年平均温度的升高,中国人男性、女性头面部头长宽指数、头长高指数、形态面指数值减小,鼻指数、容貌耳指数值增大。中国人头长宽指数的圆头型率、中头型率较高。男性、女性头长高指数均以高头型为主,头宽高指数均以狭头型率最高,形态面指数以超狭面型率最高。超过一半的人鼻指数为中鼻型,其次为狭鼻型。  相似文献   

19.
A A Frolov  I P Murav'ev 《Biofizika》1988,33(4):659-666
Informational losses in neuronal nets(NN) with plastic elements were estimated. These losses are related with 1) transition from "complicated" decoding when from the modification state of such elements information of the whole set of recorded elements is extracted to "simple" decoding natural of NN functioning when information is extracted independently for individual events; 2) uncertainty concerning NN structure, if at decoding in one of the modification states the neuron reactivity totally or the weight of plastic synapse equals zero. After the transition from complicated to simple decoding these losses for gradual plasticity are so great that NN with such plasticity has no advantages in informational capacity as compared to the binary one. These losses are absent for plasticity of Olbus type. They are relatively high for neuronal plasticity of Hebb type. For Hebb synapses their value essentially depends on the net parameters.  相似文献   

20.
藏族的体质类型和人种学特征一直受到学术界的关注。2018-2021年,我们测量了1530例卫藏、康巴和安多三个藏族人群的体质数据,统计结果发现,藏族男性、女性均为超中等身材,体质量超重,均为圆头型、高头型、中头型、中鼻型、中躯干型、宽胸型、宽肩型、宽骨盆型、中腿型,多有上眼睑皱褶,有内眦褶。对中国15个族群测量指标均数的主成分分析显示,藏族与东亚类型的汉族位点距离近于多数北亚类型族群,更近于多数南亚类型族群。藏族数据与国外资料中的东亚、南亚、北亚、北极类型数据的主成分分析结果显示,藏族与东亚类型位点最为接近。研究证实,当代藏族具有东亚蒙古人种类型的体质特征。  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