不同虫源和致害性的褐飞虱体内共生菌的种群动态

通过对不同地理种群和致害性的褐飞虱体内共生菌,在高温和抗性水稻品种作用下的种群动态研究表明,在正常湿度下褐飞虱体内共生菌的数量随若虫的生长发育而增加,5龄若虫期是共生菌增长的关键期;同一种群的褐飞虱秋季共生菌数量明显高于夏季。广西田间种群的短翅雌虫体内的共生菌数量显高于浙江省的杭州和龙游种群,经高温处理后,3个生物开共生菌数量均显减少,但其子代共生菌的数量在正常温度下马上恢复,与未经高温处理的褐飞虱共生菌数量基本相同,取食抗性品种的生物型1和田间种群的褐飞虱体内的共生菌数量均明显减少,取食抗性品种的第2代的共生菌又均比第1代少。这说明高温对共生菌的影响是暂的,而抗性品种的对共生菌的作用与褐飞虱种群对品种的适应性有关。     

Physiological roles of a yeast-like symbiote in reproduction and embryonic development of the brown planthopper,Nilaparvata lugens Stål

The physiological roles of a yeast-like symbiote in oviposition and embryonic development of its host, the brown planthopper, Nilaparvata lugens Stål, were studied using heat treatment, lysozyme injection and ligation of eggs. The eggs laid by the heat-treated females harboured only a few of the symbiotes, and their symbiote ball through embryonic development was free of symbiotes. The embryos of subsymbiotic eggs could not undergo blastokinesis and dorsal closure, and failed to hatch due to lack of differentiation of the abdominal segments. Electrophoretic profile of the eggs laid by the heat-treated females indicated the absence of several minor proteins which are usually found in the fat body of normal females. A protein (Y) of 131 kD was barely detectable in the heat-treated insects, and could not be found in the ligated eggs in which the symbiote ball was completely separated from the developing germ band. It is suggested that the symbiote supplies its host with proteins for normal embryonic and postembryonic development. The number of yeast-like symbiotes in female adults was reduced after injection with lysozyme solution, and some of the eggs were unable to hatch due to failure in blastokinesis; this was similar to the heat-treated insects. The embryos of ligated eggs could complete segmentation and differentiation normally before 110 h, but the abdominal segments failed to differentiate after dorsal closure, and regressed leaving only the head. Partially ligated eggs harboured some symbiotes and could produce normal larvae. It is concluded that the yeast-like symbiote is significant in abdominal segmentation and differentiation of the planthopper embryo.     

Relationships between the gregarine Schneideria schneiderae and its host Trichosia pubescens (Diptera,Sciaridae)

Schneideria schneiderae is a gregarine symbiote that grows within the cells of the intestinal caeca of the larvae of Trichosia pubescens (Sciaridae). The life cycles of the two organisms are synchronized so that the gregarines are at the sporozoite stage when the adult flies hatch. The adult flies disseminate the sporozoites. These are eaten by the larvae of the next generation and initiate infection. Experiments using injections of ecdysterone and removal of the neurosecretory centers by means of ligatures demonstrate the influence of the molting hormones of the host on the early extracellular stages of the symbiote and on their pairing. The molting hormones cause the gregarines to leave the cells of the caeca and influence their pairing. As soon as the gregarines leave the cells, they pair and the sexual stage starts. Studies on the survival, fertility, rate of eclosion, duration of larval life, and sex-ratio of the host show that the symbiote, under normal conditions, does not have deleterious effects on the host. Analyses of the protein contents, specific activity (counts per minute/microgram), and lysine incorporation in the intestinal caeca suggest that the metabolism of the host caeca is changed to maintain the growth of the symbiote.     

共生菌在褐飞虱致害性变化中的作用

研究了不同虫源和致害性褐飞虱Nilaparvata lugens种群体内共生菌数量动态及其对褐飞虱在抗虫品种上的取食选择、生长发育、繁殖以及氨基酸转移酶活性的影响。结果表明,褐飞虱田间种群的致害性与其体内共生菌数量有关。广西南宁种群雌成虫体内的共生菌数量显著地高于浙江杭州和龙游两个虫源的雌成虫体内共生菌数量,而已纯化的3个不同致害性生物型体内的共生菌数量无显著差异。取食抗性品种能显著减少生物型Ⅰ雌成虫体内的共生菌数量。缺乏共生菌时,生物型Ⅰ、Ⅱ若虫对水稻品种TN1和ASD7的选择性增大,而对Mudgo的取食选择性下降。尽管缺共生菌的3个生物型在已适应的和不适应的感虫和抗虫品种上的若虫存活率和雌成虫产卵量均下降,若虫历期明显延长,但在已适应品种上的变化程度明显小于在不适应的抗虫品种上的变化程度。共生菌还明显影响成虫体内丙氨酸氨基转移酶和天门冬氨酸氨基转移酶的活性。这些结果证明体内共生菌的数量和质量在褐飞虱对水稻致害性的变化中发挥了重要作用。     

Lack of DNA Homology between the Legume GLYCINE MAX and Its Symbiotic Rhizobium Bacteria

Any common genes of Glycine max and its symbiotic rhizobium bacteria 61A76 represent less than 0.6% of the bacterial genome. Thus, if any sizable exchange of DNA between host and symbiote occurs it must result in unstable DNA association which is lost with subsequent generations.     

褐飞虱共生解脂假丝酵母抗吡虫啉菌株的驯化

为进一步研究共生菌在褐飞虱对吡虫啉产生抗性中的生理生化机制,在稻田杀虫剂对褐飞虱共生解脂假丝酵母生长影响的基础上,选用不同吡虫啉浓度进行抗药性菌株的驯化。结果表明,褐飞虱共生解脂假丝酵母在不同吡虫啉浓度(2 000、1 000和500 mg/L)的固体培养基上继代培养,经过20代后2 000 mg/L培养基上的共生菌菌落数量,与未加吡虫啉的培养基上的菌落数量差异不明显,并且连续3代稳定后定为抗2 000 mg/L吡虫啉的共生菌菌株。在光镜下比较不同抗感吡虫啉菌株假菌丝的形态变化,发现抗吡虫啉菌株的假菌丝出现畸形,而且假丝变短,部分出现了膨大。     

Predicting occurrence of the fungal symbiote Harpella colonizing black fly larvae in coastal streams of Alabama and Mississippi, USA

The environmental conditions governing symbioses are poorly known in aquatic systems. Stream conditions associated with the distribution of the black fly (Simuliidae) midgut symbiote Harpella were investigated in southern Alabama and Mississippi streams. Stream conditions that were most useful in predicting the distribution of Harpella spp. in the study area were dissolved oxygen and water temperature. Presence of Harpella species in streams was associated with higher dissolved oxygen and decreased water temperature compared to streams where Harpella spp. was absent. Stream conditions associated with the distribution of Harpella spp. in other regions of the world vary according to conditions other than those elucidated here, indicating that geography, host species, and stream conditions play important roles in the spatial distribution of Harpella species.     

Initiation and orientation of the symbiote migration in the human body louse Pediculus humanus L.

Bacterial symbiotes in the human body louse Pediculus humanus migrate from the mycetome to the lateral oviducts during the adult moult. Experimental results are presented suggesting that the symbiote migration is initiated by a humoral factor associated with the adult moult; that the factor is present in both sexes but the male mycetome is unable to respond to it; and that the symbiotes are attracted by the female reproductive tract.     

Ovulation and the mechanism of follicle rupture

Summary The effects of penicillin and chlortetracyline HCl on the fine structure of the intracellular symbiotes of the pea aphid were studied in an attempt to remove the symbiote population. High penicillin concentrations, 1% and 0.1%, caused symbiote breakdown but were toxic and/or repellent to the aphids; at 0.1% specific effects were observed on the symbiotes' cell walls. After the use of 0.01% penicillin in the aphid diet, the symbiotes had abnormal cell walls and were abnormally dilated; however, symbiote division and transmission from one aphid generation to the next seemed unaffected and the aphids appeared normal. Aphids fed 0.1% chlortetracycline failed to reproduce. After 7 days, their symbiotes were found to break down at a high rate but aphid mitochondria were also adversely affected at this stage. Following 0.002% chlortetracycline, the aphids produced aposymbiotic progeny with apparently normal mitochondrial populations; these larvae failed to develop.Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, and by a research grant (GB 31904 X) from the National Science Foundation.     

Histological observations on transovarial transmission of a yeast-like symbiote in Nilaparvata lugens Stal (Homoptera, Delphacidae)

Transovarial transmission of a yeast-like symbiote (YLS) in the brown planthopper, Nilaparvata lugens Stal, was observed with light and electron microscopy. Light micrographs showed that there was no YLS in testes and spermathecae of the mated females, indicating that sperm is not involved in the transovarial transmission of the symbiote. Both light and electron micrographs showed the processes of YLS transmission from fat body to the oocyte. In females, the symbiotes in mycetocytes moved out of the syncytium, which is formed from a layer of fat body cells, by exocytosis, and released into hemocoel. Then, the free YLS in hemolymph approached to the ovarioles near pedicel and were enclosed by follicle cells. They entered the follicle cells around the primary oocyte by endocytosis at epithelial plug of the ovariole. The YLS aggregated at the posterior end of the mature egg after entering, and finally formed a symbiote ball.     

丛枝菌根共生体的氮代谢运输及其生态作用

丛枝菌根真菌能与80%的陆生维管植物形成互惠共生关系,共生体的存在对促进植物营养吸收和提高抗逆性具有重要意义.丛枝菌根真菌从宿主植物获取其光合产物碳水化合物的同时,通过外生菌丝吸收各种氮源,有效增强了宿主植物对氮素的吸收,以及氮在植物居群和群落水平上的交流,改善了植物营养代谢,增强了植物应对外界环境胁迫的能力.而共生体对氮的吸收、转运,以及氮从真菌到宿主植物的传输、代谢机制至今仍有许多问题亟待解决.本文综述了当前丛枝菌根共生体中氮传输代谢的主要机制,以及碳、磷对共生体氮传输代谢的影响;从群落和生态系统水平,简要阐述了丛枝菌根真菌在植物中氮分配的作用和对宿主植物的生态学意义,并提出共生体中氮代谢的一些需要深入研究的问题.
     

Lipids of the primary intracellular symbiote of the pea aphid, Acyrthosiphon pisum

The lipid composition of isolated primary symbiotes was investigated. The symbiotes were found to possess phosphatidyl ethanolamine, phosphatidyl choline, cholesterol, and glycerides. The fatty acids esterified to the various glycerides and glyceride derivatives were found to be predominantly C10, C12, C13, and C14 saturated components.The lipids of the pea aphid were also investigated as a measure of the purity of the symbiote preparation. The same classes of compounds were found, but the fatty acid complement was found to be different. The fatty acids were found to be predominantly C14, C18, C18:1, C18:2, and C18:3. A carotenoid-like pigment, whose absorption maximum in benzene was 460 nm, was also present.The possible significance of the various lipids to the systematic classification of the symbiotes is discussed, along with some insight into what may be an apparent dependency factor of the symbiote for the host.     

In vivo sterol biosynthesis by pea aphid symbiotes as determined by digitonin and electron microscopic autoradiography

Summary Pea aphid primary symbiotes have previously been shown to synthesize cholesterol in vitro. Two electron microscopic techniques were used here to determine whether the symbiotes also synthesize cholesterol in vivo and whether this cholesterol is made available to the aphid. We also inquired into a possible role of secondary symbiotes in cholesterol biosynthesis. Treatment of aphids with digitonin resulted in significant alteration of ultrastructural sites in primary and secondary symbiote membranes. We concluded that these sites are areas of high cholesterol concentration in the symbiotes.Electron microscopic autoradiography with ³H-mevalonate precursor indicated that both primary and secondary symbiotes synthesize cholesterol; in both cases, the majority of grains were associated with the symbiote membranes. While the frequency of grains on the symbiotes remained constant, irrespective of incubation time in labelled media, the frequency of grains over surrounding tissues increased exponentially as the time of incubation was increased from 30 min to 8 h, indicating that symbiote cholesterol is transported to other tissues. High voltage electron microscopic autoradiography permitted thick section autoradiography, reducing the time of emulsion exposure from 54 days (thin section) to 12 days (0.5 m sections).Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, and by a research grant (PCM 74-2401 A01) from The National Science FoundationThe authors wish to thank Dr. G.A. DeZoeten for his invaluable advice and assistance with the autoradiographic techniques, Mr. Gary Gaard for his help with electron microscopy, and Dr. Dale Johnston and Dr. Damien Neuberger for their generous help in the use of the high voltage EM     

江西武夷山-黄岗山西北坡森林繁殖鸟类多样性调查

研究区属于江西武夷山国家级自然保护区范围,为中国亚热带东部最高的山地,森林原生性保存较为完好。2004—2012年,在研究区海拔300—2160 m范围,布设了穿越所有代表性生境的1条主样线和6条辅助样线,共记录有森林繁殖鸟188种,占中国东部丘陵平原亚区繁殖鸟种数的71.76%。在这些繁殖鸟中,物种数在10种及以上的优势科有鸫科(Turdidae)13种、鹟科(Muscicapidae)10种、画眉科(Timaliidae)21种、莺科(Sylviidae)22种,占研究区森林繁殖鸟种数的35.1%、雀形目(PASSERIFORMES)的51.2%。将研究区按海拔高度、植被类型和人类干扰程度分为4类生境进行分析,结果显示:物种数以次生林恢复区最多(138种)原生性森林区(127种)农林营作干扰区(119种)中山灌丛草甸区(51种),其中中山灌丛草甸区由于生境条件因素各项指标数值均最小,其余3类生境分区,无论是总鸟种数、雀形目鸟种数,还是优势科鸟种数,均支持中间膨胀效应(Mid-domain effect)。G-F指数由低海拔向高海拔依次降低,即:农林营作干扰区(DG-F=0.775)次生林恢复区(DG-F=0.772)原生性森林区(DG-F=0.760)中山灌丛草甸区(DG-F=0.603);雀形目鸟种G-F指数分析,原生性森林区(DG-F=0.650)则略大于次生林恢复区(DG-F=0.633),提示顶级植物群落更大的森林内部空间和多样的内部层次结构,对雀形目鸟种多样性具有积极意义。分析显示次生林恢复区与原生性森林区相似性系数最高,表明经过30a左右自然演替恢复的次生林,对于森林繁殖鸟来说其生态功能已接近顶级群落,而农林营作干扰区和中山灌丛草甸区相似性系数最低。同时,研究区鸡形目(GALLIFORMES)鸟类生态位分异表现最为典型。     

Maintenance of the primary symbiote of the pea aphid Acyrthosiphon pisum in liquid media

The primary symbiote of the pea aphid was maintained in liquid culture media for 12 hr for the purpose of optimizing certain culture parameters. The optimum temperature for protein and nucleic acid synthesis was found to be 28–30°C. There was no dependence of this microorganism on fetal calf serum added to the growth medium. Grace's insect tissue culture medium and Grace's insect tissue culture medium (modified by Tokumitsu and Maramorosch) were found to be best suited for the maintenance of this organism.The suitability of the growth medium for the microorganism was directly related to the age of the culture medium.     

Studies on the female-sterile mutant rudimentary of Drosophila melanogaster,: I. An analysis of the rudimentary wing phenotype

The rudimentary wing phenotype was examined in detail, using six different alleles of rudimentary, and a number of points about the genesis of the r phenotype were made. (1) All of the r alleles in which the wings are defective produce wings in which the area of individual hair cells is reduced. The more severely affected the allele, the greater is the reduction in wing cell area. This reduction in area is probably uniform throughout the wing rather than localized to specific wing regions. (2) The total number of cells per wing is also greatly reduced in phenotypically r wings. As with cell area, the more severely affected the allele, the greater the reduction in cell number. However, the reduction in cell number is not uniform throughout the wing. In the less severely affected alleles, the cell number reduction is much greater in those regions of the wing which are drastically altered in shape (truncated), while those wing regions which show only slight size reductions but no overall shape changes have near normal numbers of cells. In the most deformed wings, there is a reduction in cell number throughout the wing, but again those regions with are severely truncated are the most drastically reduced in cell number. Measurements of the amount of chitin per wing indicated that the three most severely affected alleles had as much or more chitin than the wild type. It is suggested that overproduction of chitin in these alleles prevents normal expansion of the wing cells, thus increasing the severity of the wing defect. Finally, the validity and limitations of a quantitative measure of the r phenotype were defined. This measure was utilized to demonstrate a clear-cut effect of nutrition on the expression of the r phenotype.     

外生菌根对干旱胁迫的响应

从外生菌根真菌、外生菌根共生体以及外生菌根的间接作用等方面阐述外生菌根如何抵制干旱胁迫,并对未来我国外生菌根的研究提出了建议。干旱可以抑制外生菌根真菌的生长并降低其群落中真菌的多样性,干旱胁迫下外生菌根真菌子实体可以利用深度30cm以下的土壤水,子实体的表面积和体积比可作为筛选抗旱真菌的一个重要因子;在遭受干旱胁迫时,外生菌根共生体可以发生形态变化来应对干旱,同时增加了植株水分的吸收并改善了植物的光合作用、活性氧以及激素等相关代谢;外生菌根对植物生长的促进作用、增加土壤碳汇以及对其他根际微生物生长的促进作用等对宿主植物应对干旱胁迫有利。未来我国外生菌根研究应加强对干旱区优良菌-树组合的筛选工作,同时加大对乡土外生菌根真菌资源的调查力度,未来研究应重点向分子生物学领域推进。     

Anatomical characteristics of the epidermis in some cultivars ofBrassica oleracea L. distribution and structure of stomata in the cotyledons

The blade area and the number of stomata were studied in the cotyledons of five cultivars ofBrassica oleracea L., cultivated in a growth chamber and in the greenhouse, respectively. Characteristic differences between different varieties were found in the number of stomata per unit area as well as in their occurrence on both the adaxial and abaxial surfaces.     

A study of the myofibrous organization of the biceps brachii muscles from the crab-eating macaque

TheM. biceps brachii ofMacaca fascicularis was examined, noting the total number of muscle fibers, the number of muscle fibers per square millimeter, the cross sectional area of Venter musculi and the thickness of individual fibers in the cross sectional area of the right brachial biceps specimens of 10 adult crab-eating macaques, five males and five females. The results of this investigation are compared with a previous study of a similar type made on the brachial biceps of the adult human. Comparative analysis shows that the mean ventral cross sectional area of the macaque biceps muscle is 1/7 to 1/3 that of the cross sectional area in the human muscle. Macaque brachial biceps muscle shows approximately one half the total number of muscle fibers of the human specimens, though the number of fibers per square millimeter is one to two times greater than in human specimens. The macaque muscle fibers were 1/2 to 5/6 as thick as those in the human specimens. The relations between the ventral cross sectional area and thickness of individual muscle fibers is discussed. Comparisons are made between the macaque and human specimens. It is suggested that such factors as age, sex, and the nutritional history of the specimen donors may have influenced the myofibrous organization in both human and macaque specimens. It is suggested also, that differences in myofibrous organization may be related to more continuous or sustained muscular activity in the macaque and more forceful muscular contraction in humans.     

The number and distribution of vascular plant species in island forest communities in the northern part of the West Carpathian foothills

Phytosociological records were made in 80 stands lying in 50 small woodland islands in the Wierzbanówka valley. The types of communities were distinguished on the basis of numerical classification of records. These were mainly fragments of theTilio-Carpinetum association. For all the stands and for two groups of stands connected with various soils and localized mainly in the eastern or western part of the valley the statistical relationships between ten independent variables were examined (area of record, area of woodland island, its shape, distance to the nearest large woodland, mean distance to the three nearest woodland islands and others) and 10 dependent variables (number of species of trees, shrubs, herbaceous plants, species characteristic of the classesQuerco-Fagetea, Vaccinio-Piceetea, Molinio-Arrhenatheretea, Rudero-Secalietea and others). It was found that the floristic composition of the communities investigated was connected primarily with the isolation of the woodland islands. With increasing isolation the total number of species decreased, as did the number of herbaceous plants and that of herbaceous plants of the classesQuerco-Fagetea andVaccinio-Piceetea, while the number of species of the classesMolinio-Arrhenatheretea andRudero-Secalietea increased. Conditions of the habitat such as the inclination of slopes, shading, and soil fertility were less important.