A structural studies have been performed on new complex glycolipids extracted from hog gastric mucosa by 0.4 M sodium acetate in methanol-chloroform-water, and which were purified to homogeneity by DEAE-Sephadex and Florisil column chromatography and by preparative thin-layer chromatography in three solvent systems. Five branched fucolipids have been purified from this extract, three of which have been characterized previously [1] and remaining two were subject of this investigations. Based on the results of partial acid hydrolases, oxidation with periodate and chromium trioxide, permethylation and serological activities following structures were proposed:Fucolipid IVa 相似文献
Natural amino acids and sugars in intracellular eukaryotes are known to regulate adenylyl cyclase (AC) and guanylyl cyclase (GC) systems that control the most important cell processes. The goal of the present work consisted in study of effects of natural amino acids and sugars and some of their derivatives on AC and GC activities of infusoria Tetrahymena pyriformis and Dileptus anser. Methionine, arginine, lysine, and tryptamine stimulated basic AC activity of T. pyriformis, whereas alanine, thyrosine, and cysteine decreased it. Methionine, glycine, alanine, thyrosine, arginine, and to the lesser degree tryptamine and histidine stimulated AC of D. anser. The GC activity of T. pyriformis are increased in the presence of tryptamine, tryptophane, histidine, arginine, and lysine, whereas glycine and aspartic acid, on the contrary, decreased it. Tryptamine, tryptophan, leucine, glutamic acid, serine, histidine, and alanine stimulated the GC activity of D. anser. Glucose, fructose, and sucrose stimulated the basal AC activity of both infusorians and GC of T. pyriformis, with glucose and sucrose increasing AC of T. pyriformis twice, while that of D. anser 4.5 times. Lactose stimulated AC and GC of T. pyriformis and was inefficient with respect to the D. anser cyclases, whereas mannose and galactose did not affect the enzyme activities in both infusorians. The study of the chemotactic response of infusorians to amino acids and sugars indicates that involved in realization of this response can be signaling pathways both dependent on and independent of cyclic nucleotides. Thus, it has been established for the first time that several amino acids and sugars affect functional activity of enzymes with cyclase activity of the infusorians T. pyriformis and D. anser. This confirms the hypothesis that at early stages of evolution the large spectrum of comparatively simple natural molecules has a hormone-like action. 相似文献
为探究不同产地暴马丁香﹝Syringa reticulata subsp. amurensis ( Rupr.) P. S. Green et M. C. Chang〕种子和幼苗的表型性状变异规律及其与地理-气候因子的关系,以来源于黑龙江、河北、北京、内蒙古、青海和山西的10个种源(包括6个野生种源和4个栽培种源)的种子和幼苗为实验材料,对种子长和宽、种翅长和宽、百粒质量、发芽率、叶长和宽、叶长与叶宽的比值、叶柄长、株高和地径12个表型性状进行测量;在此基础上,进行了方差分析、变异系数分析、主成分分析、聚类分析及相关性分析。结果显示:暴马丁香不同种源间种子和幼苗的表型性状均有极显著差异(P=0.01),差异较大的表型性状为发芽率、百粒质量、种翅长和种翅宽。种源内和种源间各表型性状的变异系数(CV)均差异较大,种源内CV值为1.39%~45.56%,种源间CV值为6.45%~42.76%;其中,种源内种翅长和种翅宽的CV平均值较大,发芽率和百粒质量的CV平均值均较小,而种源间发芽率和百粒质量的CV值则较大。主成分分析结果表明:暴马丁香表型性状间的差异主要体现在种子长、种子宽和叶长,其次为株高、发芽率、地径、叶宽和种翅宽。根据聚类分析结果,供试的10个种源被划分为4类,其中,来源于北京和内蒙古及3个来源于河北的种源聚为Ⅰ类,来源于黑龙江哈尔滨的2个种源聚为Ⅱ类,来源于山西的2个种源聚为Ⅲ类,来源于青海的1个种源单独聚为Ⅳ类,聚类结果与各种源的地理分布有关。相关性分析结果表明:各表型性状间及表型性状与地理-气候因子间均存在不同的相关性,其中,种子发芽率与种子的其他5个表型性状均无显著相关性;经度和纬度与各表型性状均无显著相关性,而海拔、年均温和无霜期则是影响表型性状变异的主要因子。综合分析结果显示:暴马丁香各种源间存在明显的地理遗传分化,地理隔离和生态因子的大幅变化导致其种子和幼苗的表型性状变异丰富。根据研究结果,对暴马丁香的保护和利用提出了一些建议。 相似文献
As late cretaceous and Paleocene was an important stage in the evolution of
angiosperms, so studies on flora of this periiod are of great significance. In recent
years many palynological data of late Cretaceous and Paleocene have been recorded
from different parts of China, especially the Southeastern China. An attempt is made
here to allow deductions regarding the problem of existence of some palynological
provinces during this period in China. Three provinces may be divided as follows.
I. The wet subtropical and warm-temperate palynofioristical province of northeastern China. During late Cretaceous, this palynoflora was marked by occurrence
of Aquilapollenites, Mancieorpus, Fibrapollis and Wodehouseia. Aquilapollenites amplus,
A. crassus, A. megaprojeetus, A. asper, A. affenatus A. alatus, Mancieorpus andaensis,
FiburapaUis mirifieus and Wodehouseia oeulata ...... are noted.
Besides these eharacteriestic elements, there are many species of Proteaeiites and
some species of Beaupreaidites, Loranthacites, Quereoidites, Salixipollenites, Gothanipollis, Plicapollis, Utmoideipites, Cranwellia, Alnipollenites and Trieolporopollenites. Gymnosperms pollen comprise Abietineaepollenites, Pinuspollenites, Cedripites, Taxodiaceaepollenites and Araueariacites. Sehizaeoisporites are very rich in species and numbers.
Polypodiaceoisporites, Osmundacidites and Cyathidites are rarely Maud.
Paleocene palynoflora is characterized by scantiness or absence of Aquilapollenites
and Wodehouseia. Paraalnipollenites eonfusus, P. orthoeostatus, BetulaepoUenites pli
eoides and some species of Myricipites, Comptonia and Momipites are predominant.
These pollen may be related to Betulaceae, Juglandaceae and Myricaseae. Taxodiaceaepollenites, Cedripites and Podoearpidites are commen,
It reflects that during late Cretaceous the flora was wet and subtropical, but in
Paleocene, it turned to be wet and warm-temperate. According to the abundanee of
Aquilapollenites and Wodehouseia, this palynoflora may belong to the Eastern AsianWestern North American Paly-nofioristical Province.
II. Arid subtropical palynofioristieal province of South China.
During late-Cretaceous this palynofiora comprises Morinopollenites Wang & Zhao
(M. normalis, M. minor, M. polyprojeetus, M. rhombiformis) and Janhangpollis Wang
& Zhao (J. radiatus, J. arciformis, J. sayaxngensis, J. ringes, J. mikros). Besides this,
species of Proteacidites, Beaupreaidites, Myoporumpollenites, Crassimarginpollenites,
Cranwellia, Magnolipollis, Rutaceoipollenites, Ilexpollenites, Symplocospollenites, Nyssapollenites, Palmaepollenites and Chenopodipollis were recorded. Classopollis, Exessipollenites and Rugubivesieulites were abundant in this assemblage. Aquilapollenites is
rarely recorded, except along the coast region of eastern China.
In paleocene some species of Nanlingpollis Sun & He, Pentapollenites jiangsiensis,
Tricolporopollenites rombicus and Sapotaceoidaepollenitess trieoloporatus are recorded,
but Morinopollenites and Janhanpollis were unknown. Ulmoideipites, Ulmipollenites,
Ephedripites and some verrucate spores (Pterisispora) were very abundant. According
to the feature of the pouch assemblages, the flora of South China during that time was
of arid subtropical in nature. It seems to be nothing to do with other palynofloristical
provinces in the world.
III. Arid subtropical palynofloristical province of Northwestern China.
Palynofiora of this period has been recorded from a few localities throughout this
area.
Normapolles group (Atlantopollis, Pseudoatlantopollis, Chaonopollenites, BasopoUis
and ExtratriporopoUenites), Proteacigites microverrucatus, Eehitriporites magnus and
Triatriapollenites echinatus were present. Besides that, Beaupreaidites, Rutaceoipollenites, Lonicerapollis and Engelhardtioipollenits were also occurred. In gymnosperms Ephedripites and some disaccate pollen were abundant. The percentage of
Normapolles is increasing from east to west, while Proteaeidites is decreasing.
In Paleocene Nudopollis and Trudopollis of Normapolles group were present, while
Proteacidites 8issappeared.
The palynoflora of this province was of an arid and subtropical in nature, which
is somewhat in connection with the European-Eastern American Palynofloristical Province by the presence of Normapolles. 相似文献
Wetlands are a vital link between land and water in Bangladesh. A majority of the people of Bangladesh are critically dependent
on wetlands. In this paper, the values of wetlands, causes and effects of wetlands degradation, as well as the present wetlands
management approach, are analyzed and recommendations for wetlands management are suggested based on participatory rural appraisal
(PRA), field visit, personal experience, and existing literature and information. Wetlands play a crucial role in maintaining
the ecological balance of ecosystems, but wetlands habitat of Bangladesh is under constant threat due to increase of population,
intensive agriculture, overfishing, siltation, pollution, ill-planned infrastructures, lack of institutional coordination,
lack of awareness, etc. As a result biodiversity is reducing, many species of flora and fauna are threatened, wetlands-based
ecosystem is degenerating, and the living conditions of local people are deteriorating as livelihoods, socioeconomic institutions,
and cultural values are affected. Wetlands management is not addressed separately in water management activities of Bangladesh.
In order to balance human needs and wetlands conservation, a mainly community-based wetlands management approach has been
taken in Bangladesh, but this is not enough to prevent the degradation of wetlands. Therefore, Bangladesh now needs a comprehensive
strategy combining political, economic, social, and technological approaches to stop further degradation of wetlands. Therefore,
wetlands management should be incorporated into a system of integrated land and water use and, indeed, into the socioeconomic
system of the country. Policies, strategies, and management plans for sustainable use and conservation of wetlands of Bangladesh
must be based on solid knowledge and understanding of their ecological and socioeconomic functions and processes. 相似文献
The insect orders Megaloptera and Neuroptera are closely related members of the superorder Neuropterida, a relict lineage
of holometabolous insects that also includes the Raphidoptera. Megaloptera, composed of the families Sialidae and Corydalidae
(including subfamilies Chauliodinae and Corydalinae), has fully aquatic larvae that occur in a wide variety of lotic and lentic
habitats, including temporary streams. In total, 2 of 17 families of Neuroptera have aquatic larvae: Nevrorthidae live in
the benthos of fast-flowing streams and Sisyridae reside on freshwater sponges. A third family of Neuroptera, Osmylidae, contains
some water-dependent species that reside under leaves and rocks along the margins of waterbodies. We recognize 328 extant,
described species of Megaloptera (composed of 116 species of Chauliodinae, 131 species of Corydalinae, and 81 species of Sialidae)
and 73 species of aquatic Neuroptera (composed of 12 species of Nevrorthidae and 61 species of Sisyridae). Additionally, we
estimate that 45 species of Osmylidae are water-dependent, although the ecology of this group is poorly understood. Chauliodinae
and Corydalidae are both found in the New World, the Oriental region, and South Africa, but are absent from Europe, the Middle
East, Central Asia, tropical Africa, and boreal regions. Chauliodinae is quite speciose in Australia, whereas Corydalinae
is absent. Sialidae is most speciose in temperate regions, and is absent from tropical Africa and portions of the Oriental
region. Sisyridae and Osmylidae are nearly cosmopolitan, but the relict family Nevrorthidae is limited to Japan, the Mediterranean,
and Australia. The discovery of many new species in recent years, particularly among Corydalidae in the Neotropics and China,
suggests that our knowledge of aquatic neuropterid diversity is far from complete.
Guest editors: E. V. Balian, C. Lévêque, H. Segers and K. Martens
Freshwater Animal Diversity Assessment 相似文献
A variety of foods were examined for the incidence of Listeria monocytogenes, and the bacterial isolates were further characterized. L. monocytogenes was selected on LiCl-phenylethanol-moxalactam agar after enrichments and identified by several biochemical, mobility, and CAMP tests. L. monocytogenes was isolated from 58.8% of pork samples, 50% of chicken carcasses, 38% of turkey parts, 34% of frozen semiready foods, 24% of beef steaks, 12.2% of vegetables, 10.5% of seafoods, and 4.4% of frozen dim sum but was not found in the Chinese pickles and fermented milks. Isolates from seafoods, turkey parts, and beef samples had higher hemolytic activity than those from other samples. The isolates were highly susceptible to ampicillin, cephalothin, chloramphenicol, erythromycin, gentamicin, kanamycin, neomycin, novobiocin, penicillin, and streptomycin. About 14.5% of the isolates were resistant to methicillin, and 14.5% were resistant to tetracycline. The majority of the isolates from turkey parts and beef steaks were serotype 1, and those from chicken and pork samples were serotype 4 and others. Hemolytic activity, methicillin susceptibility, and serotype distribution of the isolates from domestic and imported food samples were significantly different. The results suggest the presence of food- or geography-specific L. monocytogenes strains. 相似文献
Invasive Amur honeysuckle (Lonicera maackii) creates a dense shrub layer in deciduous forests in eastern North America that negatively impacts native herbs and tree seedlings. We predicted that higher vegetative cover caused by this shrub would increase abundance and diversity of insects and alter composition of insect assemblages. We used paired plots, one with and one without honeysuckle, in ten forest locations in southwestern Ohio, USA, to sample insects and measure diversity and vertical cover of vegetation in the shrub layer. Vertical cover of this vegetation was higher on honeysuckle-present plots, but diversity of shrub-layer vegetation did not differ between honeysuckle-present and honeysuckle-absent plots. Species diversity of Hexapoda, Coleoptera, and Psocoptera, richness of Hexapoda, Coleoptera, Diptera, Hymenoptera, and Psocoptera, and abundance of Hexapoda, Diptera, Hymenoptera, and Psocoptera were higher on honeysuckle-present than on honeysuckle-absent plots. Evenness did not differ between honeysuckle treatments. Nonmetric multidimensional scaling distinguished taxonomic composition in honeysuckle-present plots from that in honeysuckle-absent plots. Presence of vertical cover explained higher richness of Hexapoda and Coleoptera, and higher abundance of Hexapoda, Diptera, Hymenoptera, and Psocoptera. Attributes of honeysuckle, independent of its contribution to vertical cover, explained increases in richness of Hexapoda, Coleoptera, and Hymenoptera and abundance of Hexapoda, Hymenopera, and Psocoptera. These attributes of honeysuckle could include a more complex vegetative structure, a greater availability of resources such as food, detritus, or shelter, and/or a more favorable cooler and moister microenvironment. To more fully understand the mechanisms causing increased richness and abundance of insects in honeysuckle-present areas, detailed studies on these attributes of honeysuckle would be necessary. 相似文献
In freshwater fishes of North Viet-Nam were found representatives of the family Waretrematidae, Carassotrema koreanum and a new species of this genus, C. ginezinskajae sp. n., close to C. koreanum and differing from it in the structure and extent of yolk glands, relatively larger sizes of the pharynx and suckers, the location of spines and body shape. The described species differs from the other species of this genus, C. mugilicola, in the shape and location of testis, structure and location of yolk glands, intestine extent, size of suckers and pharynx, presence of cirrus, location of spines on the body and in other characters. Asymphylodora pavlovskajae Ha Ky, 1969 and Asymphylodora ginezinskajae Ha Ky, 1969 are reduced to synonyms of Carassotrema koreanum and C. ginezinskajae sp. n. 相似文献
Stress activates the central and peripheral components of the stress system, i.e., the hypothalamic-pituitary-adrenal (HPA) axis and the arousal/sympathetic system. The principal effectors of the stress system are corticotropin-releasing hormone (CRH), arginine vasopressin, the proopiomelanocortin-derived peptides alpha-melanocyte-stimulating hormone and beta-endorphin, the glucocorticoids, and the catecholamines norepinephrine and epinephrine. Appropriate responsiveness of the stress system to stressors is a crucial prerequisite for a sense of well-being, adequate performance of tasks and positive social interactions. By contrast, inappropriate responsiveness of the stress system may impair growth and development, and may account for a number of endocrine, metabolic, autoimmune and psychiatric disorders. The development and severity of these conditions primarily depend on the genetic vulnerability of the individual, the exposure to adverse environmental factors and the timing of the stressful event(s), given that prenatal life, infancy, childhood and adolescence are critical periods characterized by increased vulnerability to stressors. The developing brain undergoes rapid growth and is characterized by high turnover of neuronal connections during the prenatal and early postnatal life. These processes and, hence, brain plasticity, slow down during childhood and puberty, and plateau in young adulthood. Hormonal actions in early life, and to a much lesser extent later, can be organizational, i.e., can have effects that last for long periods of time, often for the entire life of the individual. Hormones of the stress system and sex steroids have such effects, which influence the behavior and certain physiologic functions of individuals for life. Exposure of the developing brain to severe and/or prolonged stress may result in hyperactivity/hyperreactivity of the stress system, with resultant amygdala hyperfunction (fear reaction), decreased activity of the hippocampus (defective glucocorticoid-negative feedback, cognition), and the mesocorticolimbic dopaminergic system (dysthymia, novelty-seeking, addictive behaviors), hyperactivation of the HPA axis (hypercortisolism), suppression of reproductive, growth, thyroid and immune functions, and changes in pain perception. These changes may be accompanied by abnormal childhood, adolescent and adult behaviors, including excessive fear ('inhibited child syndrome') and addictive behaviors, dysthymia and/or depression, and gradual development of components of the metabolic syndrome X, including visceral obesity and essential hypertension. Prenatal stress exerted during the period of sexual differentiation may be accompanied by impairment of this process with behavioral and/or somatic sequelae. The vulnerability of individuals to develop varying degrees and/or components of the above life-long syndrome is defined by as yet unidentified genetic factors, which account for up to 60% of the variance. CRH has marked kindling and glucocorticoids have strong consolidating properties, hence both of these hormones are crucial in development and can alone produce the above syndrome. CRH and glucocorticoids may act in synergy, as in acoustic startle, while glucocorticoids may suppress or stimulate CRH, as in the hypothalamus and amygdala, respectively. A CRH type 1 receptor antagonist, antalarmin, inhibits both the development and expression of conditioned fear in rats, and has anxiolytic properties in monkeys. Profound stressors, such as those from sexual abuse, may elicit the syndrome in older children, adolescents and adults. Most frequently, chronic dysthymia and/or depression may develop in association with gastrointestinal complaints and/or the premenstrual tension syndrome. A lesser proportion of individuals may develop the classic posttraumatic stress disorder, which is characterized by hypocortisolism and intrusive and avoidance symptoms; in younger individuals it may present as dissociative personality disorder. 相似文献