<Emphasis Type="Italic">Aphidius ervi</Emphasis> Preferentially Attacks the Green Morph of the Pea Aphid, <Emphasis Type="Italic">Acyrthosiphon pisum</Emphasis>

The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae) is found in red and green color morphs. Previous work has suggested that the aphidiine parasitoid Aphidius ervi Haliday preferentially attacks green pea aphids in the field. It is not clear whether these results reflect a real preference, or some unknown clonal difference, such as in immunity, between the aphids used in the previous studies. We used three susceptibility-matched pairs of red and green morph pea aphid clones to test for preferences. In a no-choice situation, the parasitoids attacked equal proportions of each color morph. When provided with a choice, A. ervi was significantly more likely to oviposit into colonies formed from green morphs when the neighboring colony was formed from red morph aphids. In contrast, red morphs were less likely to be attacked when their neighboring colony was of the green morph. By preferentially attacking green colonies, A. ervi may reduce the likelihood of intraguild predation, as it is suggested that visually foraging predators preferentially attack red aphid colonies. Furthermore, if this host choice behavior is replicated in the field, we speculate that color morphs of the pea aphid may interact indirectly through their shared natural enemies, leading to intraspecific apparent competition.     

Three newAspergillus species isolated from clinical sources as a causal agent of human aspergillosis

Three new species ofAspergillus isolated from clinical sources in China are described and illustrated:A. beijingensis, A. qizutongii andA. wangduanlii. The first species is characterized by spreading colonies, yellow to grayish green conidial heads, smooth-walled conidiophores with a clavate vesicle, uniseriate aspergilla and nearly globose, micro-verrucose conidia. The second is characterized by spreading colonies, olive-yellow conidial heads, conspicuously roughened conidiophores with a flask-shaped vesicle, uniseriate but often secondarily proliferating aspergilla and globose, smooth conidia. The third is characterized by rapidly growing colonies, dull green conidial heads, smooth to irregularly roughened conidiophores which are often surrounded by coiled hyphae in the basal part and are terminally swollen into a globose or irregular shaped vesicle, uniseriate aspergilla and globose, micro-verrucose conidia.     

Malachite green treatment of industrial Penicillium chrysogenum protoplasts results in increased penicillin-V formation

We attempted protoplast fusion in order to generate gene transfer between an industrial strain of Penicillium chrysogenum and a fission yeast, Schizosaccharomyces pombe. The Penicillium strain was treated with malachite green. The S. pombe strain was auxotrophic for lysine. The regenerated colonies showed Penicillium morphology. The number of Penicillium colonies was significantly higher when the inactivated Penicillium protoplasts were fused to S. pombe protoplasts than in the self-fusion control experiments. We randomly isolated colonies from the regeneration plates and measured beta-lactam formation in cultures from shaken flasks. Antibiotic production was increased in colonies originated from the malachite green-treated protoplasts. Received 2 June 1998/ Accepted in revised form 30 November 1998     

Studies on the ecology of the vegetation at Mawson Statio Antarctica

The flora of Mawson Rock is fairly depauperate; the two commonest lichens are Buellia frigida and Caloplaca elegans and the only two mosses are Bryum algens and Grimmia lawiana. The lichens form open colonies on exposed rock, and closed patches on sheltered aspects. The mossfields are small and confined chiefly to gravels on northerly aspects receiving snow-bank melt waters. The moss colonies form cushions, turfs or hummocks and may be contorted by cryoturbic processes. Larger colonies thus contain greater cores of sand and gravel. Mature cushions of Bryum algens are up to 25 years old, but the deepest peats are certainly much older. The small biomass of green moss in the most sheltered sites at Mawson is similar to comparable mossfields on the exposed plateau of subantarctic Macquarie Island.     

Understanding the cause of false negative β‐d‐glucuronidase reactions in culture media containing fermentable carbohydrate

Aims:  To explain the basis for false negative β‐glucuronidase reactions seen with culture media containing lactose as a carbon and energy source. Methods and Results:  Escherichia coli strains were assessed for their reactions in culture media containing a β‐d ‐glucuronidase substrate either with or without lactose. An assay was developed to test for the expression of β‐d ‐glucuronidase at pH 5·0 and pH 7·2. Strains of E. coli that gave false negative glucuronidase reactions on media containing lactose generally expressed lower concentrations of the enzyme β‐d ‐glucuronidase than strains that gave positive results, although the difference was by no means consistent. Most strains that were negative on lactose‐containing media expressed virtually no β‐d ‐glucuronidase activity at pH 5·0. Examination of colonies on Membrane lactose glucuronide agar (MLGA) from lightly polluted water showed that c. 10% of the E. coli present failed to yield green colonies on MLGA. Conclusions:  E. coli that failed to produce green colonies on MLGA produced lower levels of β‐d ‐glucuronidase than did strains that formed green colonies, the difference being greater at pH 5·0 than pH 7·2. The false negative rate for E. coli 10% which is similar to that experienced in the study that originally described MLGA. Significance and Impact of the Study:  Strains of E. coli that fail to produce typical colonies on MLGA might produce lower concentrations of the enzyme β‐d ‐glucuronidase. Whilst the enzyme activity is sufficient to be detected at pH 7·2, fermentation of lactose significantly lowers the pH of the medium and can result in reduced enzyme activity and therefore lack of detection. The false negative rate of c. 10% would be difficult to detect in routine laboratories as it would represent 1% or less of yellow colonies being identified as E. coli (assuming E. coli accounts for 10% of the total coliform population in drinking water).     

Mutagenic effects of streptomycin in chlamydomonas

Summary Growth of a green streptomycin-resistant strain of Chlamydomonas reinhardi on a sub-lethal concentration of streptomycin on agar led to the appearance of yellow mutant cells in almost every colony. The time of appearance of the mutants varied greatly among the 9 isolates studied, each of which was selected as a single colony after repeated cloning of the parental strain. 2 isolates gave rise to colonies which responded rapidly to streptomycin (class I), 2 isolates produced yellow sub-clones as papillae only after formation of normal green colonies (class II), and 2 isolates produced stable yellow sub-clones only after a second subculture on streptomycin-agar (class III). 3 isolates were mixtures of classes II and III.The evidence that these yellow mutants arose under the mutagenic action of streptomycin is discussed in relation to the alternative possibility of their selection by the drug from a pool of pre-existing mutants. The physiological and genetic effects of streptomycin upon chlorophyll formation in Chlamydomonas are compared with reported effects of the drug upon the green flagellate, Euglena gracilis.Dedicated with appreciation and affection to Professor Dr. E. G. Pringsheim on the occasion of his 80th birthday.     

SCENEDESMUS MORPHOGENESIS. TRACE ELEMENTS AND SPINE FORMATION1

When Scenedesmus culture 16, a soil organism with numerous long spines, was grown in axenic culture in a dilute laboratory medium (with approximately 30 mg/liter total salts), spines were not formed. In this medium the organism resembled S. bijugatus, whereas S. longus and S. abundans colonies were typically formed in more concentrated media. Spines were formed on daughter colonies upon transfer to the dilute medium plus additional Fe EDTA or Ca EDTA. No other individual components of the medium did this. Spineless colonies were healthy and green with a well-defined chloroplast, provided the culture was transferred often. In addition to the absence of spines, cultures in the dilute medium had a linear arrangement of cells within a colony, along with terminal cells 20% shorter than median cells. With 4-celled spiny colonies all cells were the same length and were alternately arranged.     

Greenhead ants Rhytidoponera metallica make trade‐offs between food temperature and food concentration

1. Foraging animals are often faced with foods that vary in several important attributes, some of which may be in conflict with one another. For ectothermic animals, food temperature can be an important characteristic, as the consumption of cold foods is metabolically costly. 2. Here, the effect of food temperature on food preferences in the green‐headed ant Rhytidoponera metallica (Smith, 1858) was investigated. The first aim of the study was to determine how food concentration (caloric value) and relative food temperature influenced colony‐level preferences. We found that, all else being equal, green‐headed ant colonies preferred warmer food solutions over colder solutions, and more concentrated food solutions over less concentrated ones. 3. Next, the question of whether green‐head ant colonies could make trade‐offs between temperature and food concentration was tested. It was found that ant colonies switched their preferences in favour of a colder food solution when the colder food solution was 10 times more concentrated than the warmer food solution. 4. These experiments show that temperature is an important characteristic shaping food preferences in ants. Moreover, we show that colonies can make trade‐offs between food concentration and food temperature.     

Callus production from leaf protoplasts of various cultivars of bean (Phaseolus vulgaris L.)

High yields of viable protoplasts were obtained by enzymatic treatment from cotyledonary leaves of various greenhouse grown Phaseolus vulgaris L. cultivars. The protoplasts divided and formed cell clusters in a liquid medium. Early transfer before 10 days in the same medium was necessary for the development of cell colonies. When transferred to solid medium, the colonies gave rise to proliferating green calli. Deep green patches developed on these calli but failed to form shoots.Abbreviations NAA -NaphtaleneAcetic Acid - BA 6-Benzyl-Amino-purine - 2,4-D 2,4-Dichlorophenoxyacetic acid - GA₃ Gibberellic Acid - BCP BromoCresol Purple - MES 2-(N-Morpholino) EthaneSulphonic acid - MS Murashige and Skoog (1962)     

Pelodictyon phaeoclathratiforme sp. nov., a new brown-colored member of the Chlorobiaceae forming net-like colonies

A new strain of the green sulfur bacteria was isolated from the monimolimnion of Buchensee (near Radolfzell, Lake Constance region, FRG). Single cells were rod-shaped, nonmotile and contained gas vacuoles. Typical net-like colonies were formed by ternary fission of the cells. As photosynthetic pigments bacteriochlorophylls a, e, isorenieratene and -isorenieratene were present. Sulfide, sulfur and thiosulfate were used as electron donors during anaerobic phototrophic growth. Besides carbon dioxide, acetate and propionate could serve as carbon sources under mixotrophic conditions in the light. Like all other members of the green sulfur bacteria, the new bacterium is strictly anaerobic and obligately phototrophic. The possession of gas vacuoles and the formation of net-like colonies and the guanine plus cytosine content of the DNA (47.9 mol% G+C) are typical characteristics of the genus Pelodictyon. Because of its photosynthetic pigments which differ from those of Pelodictyon clathratiforme, strain BU 1 represents a new species, P. Phaeoclathratiforme sp. nov.     

Transformation of wheat (Triticum aestivum L.) through electroporation of protoplasts

Protoplasts isolated from embryogenic suspension cultures of wheat (Triticum aestivum cv. Hartog) were electroporated in the presence of plasmid pEmuGN and/or pEmuPAT, which contained the reporter gene gus and selectable marker gene bar, respectively. Under optimised electroporation conditions, up to 0.9% of viable protoplasts displayed gus activity two days after electroporation. To select for phosphinothricin (PPT) resistant colonies, electroporated protoplasts were incubated for six weeks in a medium containing 10 g/ml PPT. The cells surviving the selection were maintained as individual colonies on solid medium or as suspension cultures. More than 60% of these colonies exhibited tolerance to 40 g/ml PPT when tested 10 months after initial selection. To date, 57 green plants have been regenerated from these colonies and 24 have been transferred to soil. Southern blot analyses of colonies and plants, using the bar gene sequence as the probe, confirmed transformation of the cells. Positive PAT assays of both regenerated colonies and plants indicated the presence of the bar gene product. These results provide a basis for the establishment of routine procedures for transformation of wheat by direct gene transfer into protoplasts.Abbreviations gus -glucuronidase - PAT phosphinothricin N-acetyltransferase - PPT phosphinothricin - MS Murashige and Skoog medium     

Increase trend of social hymenoptera (wasps and honeybees) in urban areas,inferred from moving‐out case by 119 rescue services in Seoul of South Korea

The number of social hymenoptera have decreased due to accelerated urbanization in Seoul, Korea, during the 1970s–1990s. However, recent changes in environmental conditions have brought distinct re‐growth of their colonies. In this study, we analyzed the re‐colonization trend of social hymenoptera in Seoul with moving‐out reports submitted to 119 rescue services from 2000 to 2009. A total of 14 253 social hymenoptera findings and treatment cases were reported during that time, and the reported numbers increased continuously every year. Among them, 87% of the cases were related to social wasps and 13% were for honeybees. Social wasps peaked from July to September, when the colonies matured, whereas honeybees peaked from April to July when colonies divided. As observed by geographical information system (GIS), moving‐out cases formed hotspots in low‐story buildings around green areas such as nearby forests or city green parks in Eunpyeong‐gu and Gwanak‐gu in Seoul. Among the social wasps, the most frequent species that caused a nuisance and direct stinging was Polistes rothneyi koreanus, the majority of which nested under eaves (63%). Among the honeybees, Apis mellifera was a nuisance while attaching to buildings and walls in the city (60%) during hive splitting. We present herein the situation of the return of social hymenoptera to Seoul and discuss the possible reasons for the recent increase in social wasps in urban areas, including enlarging the green space in urban areas and stable nesting places, which benefited colony development due to the relatively higher urban temperature and the few natural predators and parasitoids.     

An examination of the role of colonial <Emphasis Type="Italic">Phaeocystis antarctica</Emphasis> in the microbial food web of the Ross Sea

The extensive buildup of phytoplankton biomass in the Ross Sea conflicts with the view that high rates of herbivory occur in all regions of the Southern Ocean. Nano and microplanktonic consumers comprise a significant fraction of total plankton biomass; however, the importance of grazing remains uncertain in the Ross Sea. Microzooplankton ingestion of solitary and colonial cells of Phaeocystis antarctica were calculated using a novel live-staining fluorescently-labeled algae method. Different morphotypes of P. antarctica were stained different colors, mixed, and observed inside Euplotes to determine their feeding preference. The blue (7-aminocoumarin) (CMAC) stain was used on the colonies and the green (CMFDA) CellTracker Probe was used on solitary cells. Both morphotypes can be seen inside the food vacuoles of the ciliate, supporting the idea that microzooplankton are capable of ingesting cells within the colonial matrix. This suggests that P. antarctica colonies enter the microbial loop in the Ross Sea before sedimentation.     

Intertrubal chloroplast transfer by protoplast fusion between Nicotiana tabacum and Salpiglossis sinuata

Summary Chloroplast tranfer was achieved by protoplast fusion between Nicotiana tobacum (Cestreae, Cestroideae) and Salpiglossis sinuata (Salpiglossideae, Cestroideae) in the family Solanaceae. Isolation of cybrid clones was facilitated by irradiation of the cytoplasm donor protoplasts, and the use of appropriate plastid mutants, streptomycin-resistant as donor, or light-sensitive as recipient. Cybrid colonies were selected by their green colour against the background of bleached (light-sensitive or streptomycin-sensitive) colonies. In the Nicotiana (Salpiglossis) cybrid plants possessing normal tobacco morphology and chromsome number, the presence of Salpiglossis, plastids was verified by restriction analysis of the chloroplast DNA. A similar analysis of the mitochondrial DNA of these lines revealed unique, recombinant patterns in the case of both fertile and sterile plants. Progeny showed no appearance of chlorophyll-deficiency in F₁ and an additional back-cross generation. Attempts at transfer of entire chloroplasts between Nicotiana tabacum and Solanum nigrum (Solaneae, Solanoideae) did not result in any cybrid cell lines in a medium suitable for green colony formation of both species. These results suggest that fusion-mediated chloroplast transfer can surmount a considerable taxonomical distance, but might be hampered by a plastome-genome incompatibility in more remote combinations.     

Foraging and leaf-cutting of the desert gardening ant Acromyrmex versicolor versicolor (Pergande) (Hymenoptera: Formicidae)

Summary Four colonies of the desert leaf-cutter ant Acromyrmex versicolor versicolor (Pergande) located 30 miles N.E. of Tempe, Arizona were observed over a 7 month period. The ants utilized trails in foraging, a characteristic of higher attines, as well as foraging singly, a typical pattern among the more primitive gardeners. The ants cut and collected both dry and green vegetation with dry grasses comprising the bulk of the forage. The ants increased their cutting of green vegetation after significant rainfall but collected dry grasses almost exclusively during dry periods. Detailed macro-motion picture analysis of leaf-cutting revealed that the desert gardener utilized a unique technique for cutting compound desert leaves.     

pGreen-S: A clone vector bearing absence of enhanced green fluorescent protein for screening recombinants

The bacterial cloning vector, pGreen-S, was constructed by inserting the enhanced green fluorescent protein (EGFP) gene at the XbaI restriction site of pUC18 plasmid. When expressed in Escherichia coli DH5α produced colonies that were an absinthe green color under daylight and strongly fluorescent green under longwave ultraviolet light. The pGreen-S vector was used to select for directional insert based on the loss of green fluorescence in recombinant colonies that was caused by the absence of EGFP. The EGFP reporter system differs from the conventional complementation of lacZ, making screening recombinants simpler, less expensive, and more effective.     

Multicellular group formation in response to predators in the alga Chlorella vulgaris

A key step in the evolution of multicellular organisms is the formation of cooperative multicellular groups. It has been suggested that predation pressure may promote multicellular group formation in some algae and bacteria, with cells forming groups to lower their chance of being eaten. We use the green alga Chlorella vulgaris and the protist Tetrahymena thermophila to test whether predation pressure can initiate the formation of colonies. We found that: (1) either predators or just predator exoproducts promote colony formation; (2) higher predator densities cause more colonies to form; and (3) colony formation in this system is facultative, with populations returning to being unicellular when the predation pressure is removed. These results provide empirical support for the hypothesis that predation pressure promotes multicellular group formation. The speed of the reversion of populations to unicellularity suggests that this response is due to phenotypic plasticity and not evolutionary change.     

Factors controlling the colonial structure of <Emphasis Type="Italic">Pediastrum tetras</Emphasis> (Chlorophyceae)

Accounting for morphological plasticity in phytoplankton populations is relevant for taxonomy, systematic/evolutionary, and ecological studies. In this work, the green alga Pediastrum tetras (Ehrenberg) Ralfs was used to describe the variation in population size structure over its growth cycle and to analyze responses to changes in biotic and abiotic factors. Pediastrum cultures reached a final stable concentration in approximately 10 days. This density (8 × 10⁵ cells ml⁻¹) remained stable for at least another 13 days and the intrinsic growth rate was 0.24 ± 0.01 day⁻¹. In the exponential phase, the relative number of single cells and the proportion of large cells (with vesicles inside) within colonies increased. When density peaked, a relative increase of single cells as well as small cells in new colonies took place. Finally, during the stationary phase, the trend reversed: fewer single cells and a larger cell size (without vesicles) were observed. Results indicated that nutrient supply could affect population structure, diminishing the proportion of eight-cell colonies. Daphnia magna Straus significantly reduced the Pediastrum population density due to predation, and this led to a significant decrease in the density of the largest colonies. In addition, info-chemicals induced a slight increase in the density of the largest colonies compared to the control treatment. Our study suggests a possible trade-off in P. tetras colonial size in natural environments: during the stationary growth period in a lake, Pediastrum populations tend to increase in size for efficient use of nutrients, while they decrease in size in the presence of herbivores. Handling editor: J. Padisak     

Isolation of somatic hybrids by cloning Nicotiana heterokaryons in nurse cultures

Fusion of Nicotiana knightiana Goodsp. and kanamycin resistant Nicotiana sylvestris Speg. et Com. protoplasts was induced by polyethylene glycol treatment. Heterokaryons were isolated by micropipette and transferred to nurse cultures of albino cells. Colonies originating from the heterokaryons could subsequently be distinguished by their green colour. The somatic hybrid nature of four such colonies was confirmed by isoenzyme pattern, kanamycin resistance and restored morphogenic potential. An additional kanamycin resistant line with characteristic Nicotiana knightiana isoenzymes was also found indicating that the drug resistance in the kanamycin resistant parent is under cytoplasmic control.Abbreviations ADH alcohol dehydrogenase - Nk Nicotiana knightiana     

ERUMPENT CEPHALODIA,AN APPARENT CASE OF PHYCOBIAL INFLUENCE ON LICHEN MORPHOLOGY1,2,3

On the upper surface of some specimens of the lichen Lobaria cf. crosa (Eschw.) Nyl. there are shrub-like growths which have a morphology similar to that of a free-living fruticose lichen, Polychidium umhausense (Auersw.) Henss., and contain a cyanophyte phycobiont, Nostoc. A few growths also contain scattered colonies of a chlorophyte phycobiont, in which case the lichen tissue locally assumes the foliose form characteristic of the parent Lobaria thallus. The differentiation of dorsiventral lichen cortices and the formation of a lax medulla and distinct algal layer are correlated with the presence of the green phycobiont. The lichen substances atranorin, gyrophoric acid, and 4-0-methylgyrophoric acid occur in both, the foliose L. erosa thallus and the fruticose tissue. It is suggested that the fruticose structures are erumpent cephalodia which are derived from the outgrowth of internal, cephalodia and should not be considered, to be epiphytic colonies of the lichen Polychidium.