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1.
One hundred and eight species of fossil spores and pollen referred to 55 genera found from the Lower Cretaceous Kapushaliang (Kizilsu) Group in the Tarim Basin of Xinjiang have been studied in this paper. The Kapushaliang Group may be divided into the Yageliemu Formation, the Shushanhe Formation and Baxigai Formation in ascending order. The Yageliemu palynoflora is characterized by the predominance of gymnospermous pollen, the relative abundance of pteridophytic spores and the absence of angiospermous pollen. Coniferae is dominant, while Lygodiaceae and Schizaeaceae are important in the flora. The most common species of palynomorphs are Todisporites minor, Cicatricosisporites dorogensis, C. australiensis, Lygodiumsporites subsimplex, Schizaeoisporites cretacius, S. zizyphinus, S. certus. Cibotiumspora paradoxa, Cyathidites australis, C. minor, Biretisporites potoniael, Cycadopites minimus, Pseudowalchia hiangulina, Parvisaccites radiatus, Podocarpidites multesimus, P. canadensis, Alisporites bilateralis, Cedripites cretaceus, C. canadenris, Abietineaepollenites microalatus, Clarsopollis classoides, C annulatus, C. xinjiangensis (sp. nov.), Ephedripites multicostatus, E. tarimensis (sp. nov.), etc . The palynoflora is comparable with those of the lower part of the Lower Xinminbu Formation in northwestern China and the lower part of the Lower Mannville Formation in western Canada, which is considered corresponding from Berriasian to Valanginian in age. The Shushanhe palynoflora is also characterized by dominance of gymnosperms and subdominance of pteridophyta. Some primitive angiospermons pollen grains are found in the upper part of the formation. In addition to the most common species of the above mentioned palynoflora, the important species in the present palynoflora comprise Cicatricosisporites potomacensis, C. orbiculatus, C. subrotundus, Concavissimisporites punctatus, C. verrucosus, C. globosus, lmpardecispora apiverrucata, Trilobosporites crassus, T. trioreticulosus, Pilosisporites verus, P. trichopapillosus, Klukisporites pseudoreticulatus, Verrucosisporites obscurilaesuratur, Converrucosisporites saskatchewanensis, Foraminisporis wonthaggiensis, Cingulatisporites valdensis, C. ruginosus, Jiaohepollis verus, Pityosporites constrictus, etc. More than 40 in dicative species of Early Cretaceous occur in the assemblage. The palynoflora compares clcsely with those of the middle part of the Lower Xinminbu Formation and the Quartz Sand Member of the Lower Mannville Formatton. It is suggested that the Shushanhe Formation should belong to Hauterivian of Barremian in age. The Baxigai palynoflora is basically similar to the Shushanhe palynoflora. But the palynoflora shows an obvious increase in abundance of lygodiaceous spores and angiospermous pollen accompanied by a great reduction of Classopollis and Ephedripltes. Most of the Early Cretaceous species occurring in the above mentioned palynofloras are present. In addition, some Cretaceous species recorded from Aptian and Albian Stages in Europe, North America and Australia, such as Trilobosporites tribotrys, T. trioreticulosus, Coptospora paradoxa, Camarozonosporites insignis, Crybelosporites punctatus, etc., appear in the assemblage. In comparison with the microfloras of the upper part of the Lower Xinminbu Formation, the Upper Mannville Formation and the lower part of the Lower Colorado Group, the Baxigai Forma- tion should be referred to Aptian to Albian in age. Judging from the palynofloras, the early Cretaceous palaeoclimate in the basin should belong to the arid or semi-arid type of the subtropic zone. However, from Barremtan through Albian the climatic conditions might appear relatively wet.  相似文献   

2.
粤港澳大湾区海岸带生态系统修复框架   总被引:1,自引:0,他引:1       下载免费PDF全文
粤港澳大湾区是全球四大湾区之一,也是我国重要的战略发展区,具有极强的开放性、经济性、生态性、社会性、海洋性和系统性特征,具有重要的理论和实践研究价值。海岸带生态系统是粤港澳大湾区重要的生态系统类型之一。受快速城市化的影响,粤港澳大湾区海岸带生态系统存在诸多问题,这些问题已成为影响陆海生态安全的重要因素。海岸带生态系统修复是国土空间生态修复的重要组成部分之一。为加快促进粤港澳大湾区海岸带修复,在分析粤港澳大湾区海岸带主要类型与特征基础上,通过剖析其现状海岸带生态修复存在的主要问题,依托山水林田湖草海生命共同体和陆海统筹等系统理念,提出粤港澳大湾区海岸带生态系统修复框架设计思路。基于粤港澳大湾区海岸带生态系统受植被、湿地、水文地质、人类活动、经济发展水平、产业发展特征、香港和澳门特别行政区等影响因素,构建了粤港澳大湾区海岸带生态系统分区、分类、分级修复框架,形成了由珠三角核心区、粤港澳大湾区、珠三角滨海城市群、珠江流域构成的粤港澳大湾区"一核一区一群一流域"海岸带生态系统修复新格局。在此基础上提出了粤港澳大湾区海岸带生态系统修复"十条"。以流域作为生态修复治理的基本单元,将影响海岸带生态系统平衡的多种因素进行分类整理,从生态系统整体性和流域系统性出发,坚持水陆联动、陆海统筹,实施以水为核心的山水林田湖草海一体化修复,从而实现粤港澳大湾区海岸带生态系统修复新目标。通过优化湾区海岸带生态环境,维护湾区海岸带生态平衡,提高湾区海岸带生态安全格局,进而促进粤港澳大湾区的可持续发展和生态文明建设。  相似文献   

3.
黑河中下游绿洲生态安全评价   总被引:49,自引:7,他引:42  
杜巧玲  许学工  刘文政 《生态学报》2004,24(9):1916-1923
生态安全包括自然生态安全、经济生态安全和社会生态安全 ,尤指自然和半自然生态系统的安全 ,即生态系统完整性和健康的整体水平反映。生态安全是维护地区或国家乃至全球的生态环境不受威胁的状态 ,能为整个生态经济系统的持续发展提供生态保障。从水安全、土地安全、经济社会安全出发 ,选取水资源量供需比、地表水质量、地下水埋深和地下水矿化度 4种水安全评价指标 ;土地人口承载度、林地覆盖率、草地载畜度、绿洲面积变化率、绿洲土地沙化率、绿洲土地盐碱化率和抗灾度等 7种土地安全评价指标 ;人均 GDP产值、单位面积农业生产总值、农民人均纯收入、绿洲人口密度、城市化率和文明度等经济社会安全评价指标 ;共计 17项 ,建立了绿洲生态安全评价综合指标体系。然后 ,应用综合评价法、层次分析法和 GIS等多种方法与手段 ,在绿洲尺度上对黑河干流中下游地区的张掖、临泽、高台、鼎新和额济纳 5个绿洲进行绿洲生态安全综合评价。评价结果显示 :自黑河中游至下游 ,各个绿洲的生态安全状况依次降低 ,最下游的额济纳绿洲生态安全仅为 4级的差状态。其中 ,水安全是关键 ,土地安全是载体 ,经济社会安全是保障 ,以上几方面相互关联 ,共同作用导致绿洲的生态安全综合水平。  相似文献   

4.
The effect of caffeic acid, a kind of catechol, on the Fenton reaction was examined by using the ESR spin trapping technique. Caffeic acid enhanced the formation of hydroxyl radicals in the reaction mixture, which contained caffeic acid, hydrogen peroxide, ferric chloride, EDTA, and potassium phosphate buffer. Chlorogenic acid, which is an ester of caffeic acid with quinic acid, also stimulated the formation of the hydroxyl radicals. Quinic acid did not stimulate the reaction, suggesting that the catechol moiety in chlorogenic acid is essential to the enhancement of the hydroxyl-radical formation. Indeed, other catechols and related compounds such as pyrocatechol, gallic acid, dopamine, and noradrenaline effectively stimulated the formation of the hydroxyl radicals. The above results confirm the idea that the catechol moiety is essential to the enhancement. Ferulic acid, 4-hydroxy-3-methoxybenzoic acid, and salicylic acid had no effect on the formation of the hydroxyl radicals. The results indicate that the enhancement by the catechols of the formation of hydroxyl radicals is diminished if a methyl ester is formed at the position of the hydroxyl group of the catechol. In the absence of iron chelators such as EDTA, DETAPAC, desferrioxamine, citrate, and ADP, formation of hydroxyl radicals was not detected, suggesting that chelators are essential to the reaction. The enhancement of the formation of hydroxyl radicals is presumably due to the reduction of ferric ions by the catechols. Thus, the catechols may exert deleterious effects on biological systems if chelators such as EDTA, DETAPAC, desferrioxamine, citrate, and ADP are present.  相似文献   

5.
Abstract— The biogeography of the cicadas of the Indo-Pacific is discussed in relation to paleogeography and compared with distribution patterns found in other groups of organisms. The cicadas show a low degree of endemism in the mainland of southeast Asia and the Greater Sunda Islands, and a high degree of endemism in Sulawesi, New Guinea, and the islands of the west Pacific. The biogeography of the cicadas of these regions with high endemism is analyzed for four groups: the subtribe Cosmopsaltriaria, the tribe Prasiini, the genus Baeturia , and the Pacific Cryptotympanini. A review of the paleogeography of the Indo-Pacific, specifying the relevant barriers, island arcs, and land connections, is provided. The recognized areas of endemism are tentatively related to the geological history of the Indo-Pacific. Areas of endemism are the Sulawesi Arcs and the Outer and Inner Melanesian Arcs. New Guinea appears to be a composite of areas of different origin: the central mountains of the Inner Melanesian Arc, the north-coast mountains of the Outer Melanesian Arc, and the Vogelkop area, which is of uncertain origin. The Papuan Peninsula of New Guinea seems to be a zone of overlap between the Outer and the Inner Melanesian Arcs. The Pacific archipelagos of the Outer Melanesian Arcs (viz., the Bismarck Archipelago, Solomon Islands, Vanuatu, and the Fiji, Tonga, and Samoa Islands) represent distinct areas of endemism. The taxon-area cladogram of the Cosmopsaltriaria gives some indication of the relationships among the areas of endemism. The discussion is extended to groups of bats, frogs, psocids, butterflies, and moths of the Melanesian Arcs, as their patterns of distribution seem equally relevant for the recognition of the biogeographic interrelationships in the Indo-Pacific.  相似文献   

6.
The availability of the complete genome of the Gram-negative beta-proteobacterium Chromobacterium violaceum has increasingly impacted our understanding of this microorganism. This review focuses on the genomic organization and structural analysis of the deduced proteins of the chemosensory adaptation system of C. violaceum. C. violaceum has multiple homologues of most chemotaxis genes, organized mostly in clusters in the bacterial genome. We found at least 67 genes, distributed in 10 gene clusters, involved in the chemotaxis of C. violaceum. A close examination of the chemoreceptors methyl-accepting chemotaxis proteins (MCPs), and the deduced sequences of the members of the two-component signaling system revealed canonical motifs, described as essential for the function of the deduced proteins. The chemoreceptors found in C. violaceum include the complete repertoire of such genes described in bacteria, designated as tsr, tar, trg, and tap; 41 MCP loci were found in the C. violaceum genome. Also, the C. violaceum genome includes a large repertoire of the proteins of the chemosensory transducer system. Multiple homologues of bacterial chemotaxis genes, including CheA, CheB, CheD, CheR, CheV, CheY, CheZ, and CheW, were found in the C. violaceum genome.  相似文献   

7.
The male reproductive organs of 16 species of Mediterranean Blenniidae ( Aidablennius sphynx, Blennius ocellaris, Coryphoblennius galerita, Lipophrys adriaticus, L. canevae, L. dalmatinus, L. nigriceps, Parablennius gattorugine, P. incognitus, P. sanguinolentus, P. rouxi, P. tentacularis, P. zvonimiri, Paralipophrys trigloides, Salaria pavo and Scartella cristata ) consist of pairs of testes, testicular glands, spermatic ducts, and blind pouches. Three main types of accessory sex organs were found by comparing the external morphology of the male gonads. Differences between species were observed in the volume of the testicular gland in relation to the volume of the testis and in the size and length of the spermatic ducts, and blind pouches. The anatomy of the testicular glands of all species investigated do not differ. Each gland consists of ducts that appear to be tubules which terminate at the testis periphery on one side and at the spermatic duct on the other side. Contrary to previous claims, A. sphynx has no fat body in place of the testicular gland; the gland of this species was not distinguishable from that of the other species investigated. In the Lipophrys species, in P. trigloides , and in B. ocellaris , a transition zone between testis and testicular gland is present. The testicular blind pouches empty into the spermatic ducts, into the ureter, or separately on the genital papilla. In most species, the epithelium has no or low folds, while in S. pavo it possesses high folds that nearly fill the lumen of the blind pouches. The morphological results are discussed in connection with taxonomy, ecology, and behaviour of the fishes.  相似文献   

8.
The embryological features of three species of Swertia ( s.l.) – S. erythrosticta , S. franchetiana , and S. tetraptera – were characterized, and the observations were used, together with previously gathered data on other species, to evaluate a recently proposed polyphyly, based on molecular data, of Swertia s.l. Comparisons of species within the genus showed that they have diversified embryologically, and there are significant between-species differences. Notable features that vary between species include the number of cell layers that form the anther locule wall, the construction of the wall of the mature anther, tapetum origin, the cell number in mature pollen grains, the structure of the fused margins of the two carpels, the ovule numbers in placental cross-sections, the shape of the mature embryo sac, the degree of ovule curvature, antipodal variation and the presence of a hypostase, and seed appendages. They share characters that are widely distributed in the tribe Gentianeae, such as a dicotyledonous type of anther wall formation, a glandular tapetum with uninucleate cells, simultaneous cytokinesis following the meiosis of the microsporocytes, tetrahedral microspore tetrads, superior, bicarpellary and unilocular ovaries, unitegmic and tenuinucellar ovules, Polygonum -type megagametophytes, progamous fertilization, nuclear endosperm, and Solanad-type embryogeny. The presence of variation in embryological characters amongst the species of Swertia s.l. strongly supports the view that Swertia s.l. is not a monophyletic group. Frasera is better separated from Swertia s.l. as an independent genus, and is only distantly related to Swertia s.s. judging from the numerous differences in embryology. Swertia tetraptera is very closely related to Halenia , as they show identical embryology.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 383–400.  相似文献   

9.
The feathers of birds develop from embryonic epidermal lineages that differentiate during outgrowth of the feather germ. Independent cell populations also form an embryonic epidermis on scutate scales, which consists of peridermal layers, a subperiderm, and an alpha stratum. Using an antiserum (anti-FbetaK) developed to react specifically with the beta (beta) keratins of feathers, we find that the feather-type beta keratins are expressed in the subperiderm cells of embryonic scutate scales, as well as the barb ridge lineages of the feather. However, unlike the subperiderm of scales, which is lost at hatching, the cells of barb ridges, in conjunction with adjacent cell populations, give rise to the structural elements of the feather. The observation that an embryonic epidermis, consisting of peridermal and subperidermal layers, also characterizes alligator scales (Thompson, 2001. J Anat 198:265-282) suggests that the epidermal populations of the scales and feathers of avian embryos are homologous with those forming the embryonic epidermis of alligators. While the embryonic epidermal populations of archosaurian scales are discarded at hatching, those of the feather germ differentiate into the periderm, sheath, barb ridges, axial plates, barbules, and marginal plates of the embryonic feather filament. We propose that the development of the embryonic feather filament provides a model for the evolution of the first protofeather. Furthermore, we hypothesize that invagination of the epidermal lineages of the feather filament, namely the barb ridges, initiated the formation of the follicle, which then allowed continuous renewal of the feather epidermal lineages, and the evolution of diverse feather forms.  相似文献   

10.
Ecological and systematic aspects of ballistosporous yeasts inhabiting the phyllosphere of the Asia-Pacific region were reviewed in the light of recent advances. In the past 20 years, the extensive isolation studies of ballistosporous yeasts were carried out in the Asia-Pacific region, and the following new species were found in the phyllosphere of the main island of Japan, of the Ogasawara Islands in the Pacific Ocean, and of Thailand, New Zealand, and the Yunnan Province of China: Bensingtonia ingoldii, B. intermedia, B. miscanthi, B. naganoensis, B. musae, B. sakaguchii, B. subrosea, B. thailandica, and B. yamatoana; Bullera boninensis, B. coprosmaensis, B. hannae, B. huiaensis, B. miyagiana, B. mrakii, B. oryzae, B. penniseticola, B. pseudoalba, B. schimicola, B. sinensis, B. unica, B. variabilis, and B. waltii; Kockovaella imperatae, K. machilophila, K. phaffii, K. sacchari, K. schimae, and K. thailandica; Sporobolomyces blumeae, S. coprosmae, S. coprosmicola, S. dimmenae, S. draycophyllus, S. falcatus, S. griseoflavus, S. inositophilus, S. lactophilus, S. linderae, S. novazealandicus, S. nylandii, S. oryzicola, S. poonsookiae, S. ruber, S. sasicola, S. subbrunneus, S. taupoensis, S. vermiculatus, S. xanthus, and S. yunnanensis; and Udeniomyces megalosporus. Yeast species containing Q-10(H(2)), a monohydrated ubiquinone, have long been considered to be rare yeasts; however, these yeasts were proved to be common in the tropical and subtropical phyllosphere of Asia. The chemotaxonomic and molecular phylogenetic studies based on the sequence analysis of 18S rDNA revealed the heterogeneity of ballistosporous yeasts, which comprised species with polyphyletic phylogenetic origins. A new phylogenetic cluster, Subbrunneus, was newly found in the class Urediniomycetes as the fifth phylogenetical cluster of this class, based on the analysis of 18S rDNA sequences. The Subbrunneus cluster comprises four ballistosporous yeast species found in the phyllosphere of Japan and New Zealand. The future perspectives of basidiomycetous yeast systematics are discussed.  相似文献   

11.
The Cuban species of Calisto are reviewed based on the morphology of adult and immature stages, as well as DNA sequences of six genes (COI, EF1α, wingless, GAPDH, RpS5, CAD). A new species, Calisto occultasp. n., is described from the northeastern Cuban mountains. Calisto smintheus Bates, 1935 and Calisto bruneri, Michener 1949 are revised and revalidated. A new status, the species level, is proposed for Calisto brochei, Torre 1973, Calisto muripetens, Bates 1939 and Calisto bradleyi, Munroe 1950. The immature stages of Calisto smintheus, Calisto brochei,and Calisto occulta are described for the first time, and those of Calisto herophile, Hübner 1823 are redescribed. Useful morphological characters for adults are the shape and conspicuousness of androconial patch, the number and relative size of white dots on underside of hindwing, the shape of aedeagus, the shape of digitiform projection of genitalia valve, the shape and relative size of tegumen and uncus, the relative size of female genitalia, the height of sterigmal ring dorsal crown of the latter, and the relative size of corpus bursae and ductus bursae. For the immature stages, the most important characters are the color pattern of head capsule, the number and width of longitudinal lines of body, in the larvae; and the color pattern and the absence or presence of dorsal ridges on the abdomen of pupae. The phylogenetic relationships between the Cuban Calisto species are quite robust and well-supported; however, conflict between mitochondrial and nuclear datasets was detected in Calisto brochei, Calisto muripetens and to a lesser degree in Calisto bradleyi.  相似文献   

12.
【目的】肠道微生物在宿主的多种生命活动中发挥重要作用。本研究旨在通过研究植物乳杆菌Lactobacillus plantarum, 苹果醋酸杆菌Acetobacter malorum和酿酒酵母Saccharomyces cerevisiae 3种微生物对黑腹果蝇Drosophila melanogaster觅食、产卵和发育的影响,进一步阐明肠道微生物与宿主的互作调控机制。【方法】采用引诱实验检测体外培养的植物乳杆菌、苹果醋酸杆菌和酿酒酵母对交配前后黑腹果蝇成虫的引诱力以及这3种微生物的单一微生物和其中2种或3种微生物的混合物对非处女蝇的引诱力。采用产卵选择实验检测黑腹果蝇非处女蝇对单一微生物和其中2种或3种微生物的混合物的产卵偏好。将黑腹果蝇卵在接种分别含有植物乳杆菌、苹果醋酸杆菌和酿酒酵母的培养基和正常培养基(对照)上培养,测量幼虫体重;同时将卵在分别含有活菌或灭活的这3种单一微生物的培养基上和正常培养基上培养,统计化蛹数,以检测不同微生物对黑腹果蝇幼虫发育的影响。将黑腹果蝇幼虫在分别含有植物乳杆菌、苹果醋酸杆菌和酿酒酵母的培养基及正常培养基中培养72 h,qRT-PCR检测胰岛素信号通路的关键基因InR在黑腹果蝇幼虫中的相对表达量变化。【结果】苹果醋酸杆菌主要影响黑腹果蝇的产卵,酿酒酵母和植物乳杆菌则可同时影响黑腹果蝇觅食和产卵,且与单一微生物相比,非处女黑腹果蝇更趋向于含有2种或3种微生物的混合物。产卵选择实验表明,3种单一供试微生物及其中2种或3种微生物的混合物对黑腹果蝇的产卵选择具有显著的吸引力,其中混合物的影响最大,然后依次是苹果醋酸杆菌、酿酒酵母、植物乳杆菌。3种微生物均可促进黑腹果蝇幼虫的发育,活菌在接种早期加快幼虫到蛹的发育,灭活菌的促进作用则相对滞后。与对照比较,InR在接种苹果醋酸杆菌的培养基上培养的黑腹果蝇幼虫中的表达量显著降低,而在分别接种植物乳杆菌和酿酒酵母的培养基上培养的幼虫中则被显著促进表达。【结论】苹果醋酸杆菌可引诱黑腹果蝇的产卵,酿酒酵母和植物乳杆菌对黑腹果蝇的觅食和产卵都有具有引诱力;同时微生物的多样性可增加黑腹果蝇的觅食和产卵偏好。植物乳杆菌、苹果醋酸杆菌和酿酒酵母可能通过不同的调控机制影响黑腹果蝇幼虫的生长发育。  相似文献   

13.
奶牛精子尾部主段的中央结构为轴丝。在轴丝的外方有外周致密纤维。外周致密纤维由中段延伸而来。进入主段后,9条外周致密纤维逐一终止。最早终止的是第8条纤维。随后的终止顺序是第3、7、4、2、6、5、9、1条。因此,9条外周致密纤维中,最长的是第1条纤维,最短的是第8条纤维。9条纤维按长短顺序排列依次是第1、9、5、6、2、4、7、3、8条。根据外周致密纤维数量的多寡,可以将主段分为10个区域。从近中段端至近末段端,这10个区域依次是9条、8条、7条、6条、5条、4条、3条、2条、1条、0条纤维区域。外周致密纤维的外方有一纤维鞘。纤维鞘的背侧纵柱和腹侧纵柱分别向内伸出一个嵴。在主段的0条纤维区域,纤维鞘直接位于轴丝之外。在纤维鞘的外方还有精子的细胞质膜。  相似文献   

14.
Study of morphological characters to identify the subspecies of Hyalomma marginatum immature stages is based on material collected throughout all the geographical range of the species. As it was found, the discrimination of subspecies of H. marginatum immature stages needs a complex use of structural and morphometrical characters. Only H. m. marginatum larvae and H. m. isaaci nymphs may be easily differentiated from other subspecies based on the structural (qualitative) characters. Besides, morphometric (quantitative) characters should be used only in combinations for identification of the subspecies. In regard to structural characters of larvae, it was found that the shape and size of coxal spurs of H. marginatum allow differentiating this subspecies from the others (Fig. 3, 5, 6). Based on morphometrical characters of larvae, the following characteristic features of subspecies have been found: in H. m. marginatum, the capitulum is wide, the palpi, hypostome and genua I are short and narrow; in H. m. turanicum, the capitulum is narrow, the palpi are short and narrow, the hypostome is short and wide, the genua I are long and narrow; in H. m. rufipes, the scutum is large, the capitulum is wide, the palpi are long and narrow, the hypostome and genua I are long and wide; in H. m. isaaci, the scutum is small, the capitulum is narrow, the palpi and hypostome are long and narrow, the genua I are short and narrow. Among structural characters of nymph, several discriminative features of subspecies have been found. The shape of the scutum in H. m. isaaci (Fig. 2, 2) clearly differentiates this subspecies from the others (Fig. 2, 1). In H. m. marginatum, the setae of alloscutum as a rule have bluntly rounded apices (Fig. 1, 2), while in the other subspecies these setae are more tapering apically (Fig. 1, 1). The shape of spiracular plates is rather variable within the species, but in H. m. marginatum and H. m. isaaci (Fig. 1, 3) the plates are larger and more perforated than in H. m. rufipes and H. m. turanicum (Fig. 1, 4). In H. m. isaaci, the spurs of coxae I are narrower than in other subspecies (Fig. 1, 8). Based on morphometrical characters of nymphs, the following discriminative features of subspecies have been found: in H. m. marginatum, the capitulum is wide, the palpi are short and wide; in H. m. turanicum, the capitulum is narrow, the palpi are long and narrow; in H. m. rufipes, the scutum is wide, the capitulum is narrow, the palpi are long and narrow, the hypostome is long; in H. m. isaaci, the scutum is long and narrow, the capitulum is wide, the palpi are short and wide, the hypostome is short.  相似文献   

15.
防护林阶段定向经营研究I.理论基础   总被引:3,自引:0,他引:3  
姜凤岐  朱教君 《应用生态学报》2002,13(10):1352-1355
基于多年防护林经营研究与实践,在分析防护林经营目的的基础上,提出了防护林阶段定向经营理论基础,以防护林的防护成熟为核心,将防护林经营阶段划分为成熟前期,即从栽植后形成相对稳定的幼林到初始防护成熟龄;防护成熟期,防护成熟状态持续的时期,即从初始防护成熟龄到终止防护成熟龄;更新期,林木接近自然成熟开始更新直到更新结束并形成相对稳定的幼林,防护林经营的定向是指在任何经营阶段内,一切经营技术与措施都是为了使防护林向着成熟的状态发展,即防护成熟是防护林经营的方向,是最终目的,为尽量维持防护林的成熟状态并使防护效益不间断,针对发育正常与低质衰退的林分,在各个经营阶段内采取相应的系列经营管理与改造措施。  相似文献   

16.
杨蓓芬  杜乐山  李钧敏   《生态学杂志》2015,26(11):3309-3314
为了阐明南方菟丝子寄生对加拿大一枝黄花生长和繁殖的影响及机制,分析了南方菟丝子寄生对加拿大一枝黄花形态、生长与繁殖指标的影响,并分析了其生物量与加拿大一枝黄花次生代谢产物含量的相关性.结果表明: 南方菟丝子寄生显著降低加拿大一枝黄花株高、基径、主根长度和根直径,显著降低根、茎、叶和总生物量以及花序数、花序主轴长和花序分枝数;尤其是株高、花序数、茎生物量3个指标,被南方菟丝子寄生的植株仅为无寄生植株的1/2、1/5和1/8.南方菟丝子寄生强度对加拿大一枝黄花的株高、根长、茎生物量、总生物量等指标没有显著影响,但高强度寄生组的基径、根体积、叶生物量、根生物量、花序数、花序主轴长、花序分枝数等指标均显著低于低强度寄生组.南方菟丝子寄生显著增加加拿大一枝黄花根鞣质含量和茎黄酮含量.加拿大一枝黄花的生物量与根鞣质含量及茎黄酮含量存在显著负相关.这表明南方菟丝子寄生加拿大一枝黄花后, 除了减少其资源获取外,还可能通过改变资源分配方式等途径进一步抑制其生长.  相似文献   

17.
Numbers of species and genera,endemic genera,extant primitive genera,relationship and distribution patterns of presently living Chenopodiaceae(two subfamilies,12 tribes,and 118 genera)are analyzed and compared for eight distributional areas,namely central Asia,Europe,the Mediterranean region,Africa,North America,South America, Australia and East Asia. The Central Asia,where the number of genera and diversity of taxa are greater than in other areas,appears to be the center of distribution of extant Chenopodiaceae.North America and Australia are two secondary centers of distribution. Eurasia has 11 tribes out of the 12,a total of 70 genera of extant chenopodiaceous plants,and it contains the most primitive genera of every tribe. Archiatriplex of Atripliceae,Hablitzia of Hablitzeae,Corispermum of Corispermeae,Camphorosma of Camphorosmaea,Kalidium of Salicornieae,Polecnemum of Polycnemeae,Alexandra of Suaedeae,and Nanophyton of Salsoleae,are all found in Eurasia,The Beteae is an Eurasian endemic tribe,demonstrating the antiquity of the Chenopodiaceae flora of Eurasia.Hence,Eurasia is likely the place of origin of chenopodiaceous plants. The presence of chenopodiaceous plants is correlated with an arid climate.During the Cretaceous Period,most places of the continent of Eurasia were occupied by the ancient precursor to the Mediterranean,the Tethys Sea.At that time the area of the Tethys Sea had a dry and warm climate.Therefore,primitive Chenopodiaceae were likely present on the beaches of this ancient land.This arid climatic condition resulted in differentiation of the tribes Chenopodieae,Atripliceae,Comphorosmeae,Salicornieae,etc.,the main primitive tribes of the subfamily Cyclolobeae. Then following continental drift and the Laurasian and Gondwanan disintegration, the Chenopodiaceae were brought to every continent to propagate and develop, and experience the vicissitudes of climates, forming the main characteristics and distribution patterns of recent continental floras. The tribes Atripliceae, Chenopodieae, Camphorosmeae, and Salicornieae of recent Chenopodiaceae in Eurasia, North America, South America, southern Africa, and Australia all became strongly differentiated. However, Australia and South America, have no genera of Spirolobeae except for a few maritime Suaeda species. The Salsoleae and Suaedeae have not arrived in Australia and South America, which indicates that the subfamily Spirolobeae developed in Eurasia after Australia separated from the ancient South America-Africa continent, and South America had left Africa. The endemic tribe of North America, the tribe Sarcobateae, has a origin different from the tribes Salsoleae and Suaedeae of the subfamily Spirolobeae. Sarcobateae flowers diverged into unisexuality and absence of bractlets. Clearly they originated in North America after North America had left the Eurasian continent. North America and southern Africa have a few species of Salsola, but none of them have become very much differentiated or developed, so they must have arrived through overland migration across ancient continental connections. India has no southern African Chenopodiaceae floristic components except for a few maritime taxa, which shows that when the Indian subcontinent left Africa in the Triassic period, the Chenopodiaceae had not yet developed in Africa. Therefore, the early Cretaceous Period about 120 million years ago, when the ancient Gondwanan and Laurasian continents disintegrated, could have been the time of origin of Chenopodiaceae plants.The Chinese flora of Chenopodiaceae is a part of Chenopodiaceae flora of central Asia. Cornulaca alaschnica was discovered from Gansu, China, showing that the Chinese Chenopodiaceae flora certainly has contact with the Mediterranean Chenopodiaceae flora. The contact of southeastern China with the Australia Chenopodiaceae flora, however, is very weak.  相似文献   

18.
草鱼鳃上寄生毛管虫一新种——变异毛管虫的研究   总被引:1,自引:1,他引:0  
吸管亚纲(Subclass suctoria)中,多数种类具有或长或短的炳,附着它物上营固着生活。寄生在鱼类体表、鳃丝内的毛管虫(Trichophrya)和簇管虫(Erastophrya)的种类中,至今未见报道有固着柄的代表。    相似文献   

19.
The fecal flora of 35 breast-fed and 35 bottle-fed babies was determined. Bifidobacteria were the predominant fecal bacteria in both groups. Conversely, the counts of most of the other bacteria, such as bacteroides, eubacteria, peptococci, veillonella, clostridia, enterobacteria, streptococci, and bacilli in the bottle-fed group were significantly higher than those in the breast-fed group. The frequencies of occurrence of lecithinase positive clostridia, clostridia-others, pseudomonas and bacilli in the bottle-fed group were significantly higher than those in the breast-fed group. Twenty-one genera and 103 species or biovars of microorganisms were isolated from the feces of the breast-fed group and 20 genera and 97 species or biovars from the bottle-fed group. The organism that showed the highest number and the highest frequency of occurrence in both groups was Bifidobacterium breve. Bifidobacterium infantis, which was formerly the most prevalent Bifidobacterium species in baby feces, was never isolated in this study. Further, the counts and incidences of Clostridium paraputrificum, C. perfringens, and Bacillus subtilis, the counts of C. clostridiiforme, Bacteroides vulgatus, Veillonella parvula, Lactobacillus acidophilus, Escherichia coli, Streptococcus bovis, S. faecalis, and S. faecium and the incidences of C. difficile, C. tertium, and Pseudomonas aeruginosa in the bottle-fed infants were significantly higher than those in the breast-fed infants.  相似文献   

20.
电活性微生物是一类能够通过直接接触、导电菌毛或氧化还原介质与电极或者其他细胞进行胞外电子传递的微生物。而在这个过程中,胞外聚合物(extracellular polymeric substances, EPS)扮演着重要的角色。EPS是微生物生长过程中通过细胞裂解、水解分泌的高分子聚合物的混合物,主要由蛋白质、多糖和腐殖质等物质组成。来自电活性微生物的EPS的不同组成成分和特性会对EPS的电活性以及电活性微生物胞外电子传递产生一定的影响,同时在环境应用方面发挥重要作用。因此,为了更全面了解电活性微生物EPS的电活性及其对电活性微生物胞外电子传递的作用,本文总体介绍了电活性微生物EPS的电活性的直接表征方法,再从组成成分、化学性质、物理性质和空间分布4个方面综述了其对EPS电活性的影响及其在电子传递中的作用,介绍了当前电活性微生物EPS在染料废水脱色、重金属吸附、有机污染物的生物转化和渗滤液管理等方面的环境应用,并从表征方法、试验规模和互作机理研究等角度展望了未来的研究方向。  相似文献   

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