AUTOTROPHIC AND HETEROTROPHIC NUTRITIONAL BUDGET OF SALT MARSH EPIPHYTIC ALGAE1

This paper addresses the nutrition and relative importance of primary production to heterotrophy of select unicellular green algae and diatoms from the same assemblage. Algal growth responses to nutrient additions varied widely. Such responses included: inhibition and enhancement of growth by amino acid additions: nonstimulation or inhibition by most sugars 10 mM concentration; glucose stimulation of 6 and inhibition of 3 species; fructose inhibition of 6- and 3- fold stimulation of one species; stimulation of most species by a vitamin mixture, some natural products, metabolite mixtures, etc. Photoassimilation of glucose and aculeate in 8 of 12 species occurred. Nine of 12 species took up only a fraction of the total carbon fixed as organic substrate. Enhancement of photosynthesis by glucose and inhibition by acetate was common. The data suggest that attached littoral and shoal marine algal assemblages may play mixed trophic roles lower levels of the detrital food web.     

TIME OF ORIGIN AND BIOGEOGRAPHICAL HISTORY OF SPECIALIZED RELATIONSHIPS BETWEEN NORTHERN MARINE PLANTS AND HERBIVOROUS MOLLUSCS

A survey of cool-temperate North Pacific and North Atlantic marine plants and herbivorous molluscs and their descendants was undertaken to determine the time of origin and the biogeographical history of specialized host-guest relationships between plants and herbivores. Of 12 such associations, 6 (50%) were established no earlier than the Pliocene. These six associations resulted from the invasion of either the plant (three cases) or the herbivore (three cases) from geographical regions other than the one in which the association was forged. These results are contrary to the widely held view that specialized (“coevolved”) relationships tend to be ancient, and highlight the importance of biotic interchange as a biogeographical process influencing the opportunity for trophic specialization.     

蚜虫寄主植物与取食部位的多样性

在中国科学院动物研究所已有标本采集记录和国内外文献资料的基础上,分别从蚜虫类Aphidina科级和属级阶元系统研究世界范围内蚜虫寄主植物与取食部位的多样性.蚜虫的寄主植物种类繁多,涉及267科2120属,尤其以菊科、禾本科、豆科、伞形科、唇形科、蔷薇科、茜草科、兰科、壳斗科、杨柳科、胡桃科等植物为主.13科蚜虫的寄主植物差别很大:在科级水平,球蚜科Adelgidae、纩蚜科Mindaridae和平翅绵蚜科Phloeomyzidae的寄主植物类群比较单一,蚜科Aphididae和瘿绵蚜科Pemphigidae的寄主植物范围最为广泛;在属级水平,各属蚜虫间寄主植物也有明显差异,有143属蚜虫的寄主植物多于2科,其中蚜科的属占多数,蚜属Aphis、瘤蚜属Myzus、长管蚜属Macrosiphum、粗额蚜属Aulacorthum和声蚜属Toxoptera的寄主植物最多,各超过100科290属.在不同的寄主植物上寄生着不同种类的蚜虫,其中16科47属寄主植物上寄生的蚜虫多于14属.蚜虫在寄主植物上的取食部位丰富多样,可分为7类,分别为叶片、嫩梢、嫩枝、茎、花、根部、果实等.以叶片、茎、嫩枝和嫩梢为蚜虫主要取食部位.平翅绵蚜科主要取食嫩枝、茎和根部,短痣蚜科Anoeciidae主要取食叶片、嫩梢和根部,球蚜科、群蚜科Thelaxidae和毛管蚜科Greenideidae取食叶片、嫩梢、嫩枝和茎等部位,纩蚜科取食叶片、嫩梢、茎和花等部位,大蚜科Lachnidae和斑蚜科Drepanosiphidae除取食叶片、嫩梢、嫩枝、茎等部位外,前者还在根部取食,后者还寄生在果实上,根瘤蚜科Phylloxeridae在除花以外的其它6个部位取食,蚜科、瘿绵蚜科和毛蚜科Chaitophoridae的取食部位最为多样,它们在上述7个部位均可取食.还初步讨论了在不同寄主植物上蚜虫物种的分化,以及蚜虫与寄主植物之间的对应关系.     

A COMPARISON OF ROOT CAP CELLS OF EPIPHYTIC,TERRESTRIAL AND AQUATIC PLANTS

Outer cells from the root cap of Cattleya orchids are characterized by their secretory activity. They are arranged in layers intercalated with layers of secretory product and form a protective mantle over the root tip. The ultrastructure of these cells is similar to those of terrestrial roots (for example Zea mays) in that they are characterized by copious quantities of endoplasmic reticulum and numerous dense-staining prevacuolar bodies. In contrast, most root cap cells of water hyacinth and duckweed are highly vacuolate with no dense-staining prevacuolar bodies. The endoplasmic reticulum is sparse and dictyosomes are small and without secretory activity.     

BIOGEOGRAPHY OF MARINE RED ALGAE: MYTHS AND REALITIES

Hommersand, M. H. Department of Biology, Coker Hall, University of North Carolina, Chapel Hill, NC 27599-3280 USA Theories about the geographical distribution of marine algae fall roughly into two categories: (1) a concept of biogeographical regions in which algal distribution is determined primarily by growth, reproductive and lethal temperature boundaries (Setchell, van den Hoek, Breeman, Lüning) and (2) an historical perspective in which distribution is determined primarily by patterns of dispersal and the establishment of barriers to dispersal (vicariance biogeography) (Svedelius, Garbary, Lindstrom, Hommersand). Setchell proposed the 5° isotherm rule in 1920, and in 1924 Svedelius advocated a worldwide distribution for tropical and subtropical groups followed by discontinuous distribution upon closure of the connection between the Indian Ocean and Mediterranean Sea and, later, between North and South America (Wegener's theory). Transarctic dispersal routes have received special attention in recent years (Lindstrom, Lüning, van Oppen, Olsen, Stam), as have special relationships between Australasia, South Africa and South America (Hommersand). Less well understood are the climatic changes that have taken place in the Cenozoic which are strategic to an understanding vicariant biogeography. The advent of molecular methods combined with the tools of phylogenetic systematics now make it possible to identify ancestral taxa, test the consistency of tree topologies, and calculate mean branch lengths between sister lineages diverging from an interior node of a tree. With such methods it may be possible to infer ancestral areas, identify dispersal pathways, determine the chronology of isolating events, assess the impact of multiple invasions, and generally relate dispersal and vicariance models to phylogenetic hypotheses for red, brown and green algal taxa.     

海洋天然产物的研究与开发

人们已从海藻、腔肠动物、海绵、海鞘、苔藓虫、软体动物、鱼类等海洋生物中分离到大量化学结构独特、生理活性强烈的物质。这些物质的化学结构可分为:聚醚类、大环内酯、萜类、生物碱、环肽、甾醇、多糖和不饱和脂肪酸等。其中,许多具有抗菌、抗真菌、抗肿瘤、抗病毒和心脑血管活性等作用,有的已进入临床试验阶段,可望发展成新药。     

BENTHIC ALGAE OF SOUTHERN BAFFIN ISLAND. III. EPILITHIC AND EPIPHYTIC COMMUNITIES1

Blue-green algae–mainly Aphanocapsa pulchra (Kz.) Rabh., Oscillatoria tenuis Ag., Schizothrix muelleri Naeg., and Lyngbyn spp.—were predominant, in the epilithic communities of Baffin Island rivers and lakes during 1972, usually accounting for more than 90% by numbers and volume of the total flora. Diatoms were only important early in the growing season (June) with Achnanthes marginulata Grun., A. kriegeri Krasske, and Tabellaria flocculosa (Roth) Kz. being most common. Standing crop in one river increased from near 0 in June to 6.0 × 10⁴ cells/cm² (2.2 × 10⁸μ³/cm²) in July and back to near 0 again by October. Low levels of nitrate nitrogen probably limited algal numbers, while flooding, light, and grazing by herbivores appeared to have little effect. Changes in algal standing crop in the lakes followed much the same pattern as outlined above. However, the maximum amount of algae was considerably greater than that recorded from the rivers, reflecting the greater availability of nutrients. Lyngbya nana Tild. was the main algal species attached, to filaments of Mougeotia sp., reaching greatest development (5.0 × 10⁴ filaments/cm²) during September. On the other hand, diatoms–mainly Ceratoneis arcus Kz. and varieties, Fragilaria spp., and Synedra spp.–were predominant in the community floating among the filaments with maximum standing crop (64.48 × 10⁶ cells/g dry weight of Mougeotia) occurring in July. The small diameter of the Mougeotia filaments was probably the main factor limiting the size of both the attached and free-floating communities.     

浮水植物化感作用抑制藻类的机理与应用

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棉铃虫迁飞规律及其与寄主植物的互作关系研究进展概况

用飞行磨、透射电镜、风洞等测定了棉铃虫Helicoverpa armigera(Htibner)成虫的飞行能力和飞行肌结构的变化,结合不同虫源滞育条件及抗寒能力比较、蛹与成虫的形态学比较及分子生物学标记、幼虫抗药性地理分布、海轮上捕捉、成虫携带花粉的分析和小规模成虫颜色标记-释放-回收试验,证明棉铃虫是一种典型的兼性迁飞性害虫;初步推断辽河流域特早熟棉区的棉铃虫虫源来自黄河流域棉区,各相邻的棉区之间有频繁的棉铃虫种群交流。观察棉铃虫触角上不同类型嗅觉感器的形态和分布,用EAG、GC-EAG、GC-MS等测试分析了棉铃虫对不同植物各器官抽提物的电生理反应及抽提物中的活性组分。发现吸引棉铃虫取食的挥发性它感化合物主要为极性较小的单萜烯类,而吸引其产卵的主要为倍半萜烯类及其它一些极性较大的化合物。改进了测定棉株内抗生性次生代谢产物的定性、定量方法,研究了棉酚、单宁对棉铃虫发育、繁殖的影响及2类次生物间的交互作用,通过杂交初步探讨了棉花常规抗虫性的遗传特性,并尝试了切断胚轴和转Bt基因内生菌处理棉花增强抗虫性的作用。认为在利用棉花自然抗虫性的同时,应结合各种人为手段增强其抗性,使其在棉铃虫猖獗条件下发挥更大的控制作用。从气候、营养、天敌、抗药性等方面研究了棉铃虫猖獗原因,初步认为：气候干旱是棉铃虫暴发的最主要环境条件,施肥水平特别是施氮量的日益增高是棉铃虫严重性上升的主要物质基础,而不合理使用化学农药是造成棉铃虫种群失控的主要人为因子。     

CAROTENOID COMPOSITION OF MARINE RED ALGAE1

Photosynthetic organisms possess carotenoids that function either as accessory, photoprotective, or structural pigments. Therefore, the carotenoid profile provides information about certain photoacclimation and photoprotection responses. Carotenoids are also important chemosystematic markers because specific enzymes mediate each step of carotenoid biosynthesis. For red algae, diverse and often contradictory carotenoid compositions have been reported. As a consequence, it is difficult to infer the physiological importance of carotenoids in Rhodophyta. To characterize the relationship between carotenoid composition, rhodophycean phylogeny, and the presence of potentially photoprotective pigments, we analyzed the carotenoid composition of 65 subtropical species from 12 orders and 18 rhodophyte families. Our results showed that red algae do not present a unique carotenoid profile. However, a common profile was observed up to the level of order, with exception of the Ceramiales and the Corallinales. The main difference between profiles is related to the xanthophyll that represents the major carotenoid. In some species lutein is the major carotenoid while in others it is substituted by zeaxanthin or antheraxanthin. The presence of this epoxy carotenoid together with the presence of violaxanthin that are xanthophyll cycle (XC)‐related pigments was found in four of the 12 analyzed orders. The carotenoid pigment profiles are discussed in relation to Rhodophyta phylogeny, and it is suggested that the xanthophyll cycle‐related pigments appeared early in the evolution of eukaryotic phototrophs.