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  • Saccharomyces cerevisiae  (243)
  • Coleoptera  (217)
  • Zea mays  (193)
  • Springer  (647)
  • 1990-1994  (647)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 201-209 
    ISSN: 1570-7458
    Keywords: Hypothenemus hampei ; coffee berry borer ; abiotic mortality ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mortality of the coffee berry borer was studied under controlled laboratory conditions in Tapachula, Mexico. For adult female borers subjected to a range of relative humidities (RH) without food at 25°C, the longest mean survival time (20 days) was obtained at 93.5% RH. Adult borer survival was also studied at a range of temperatures for a fixed relative humidity (93.5% RH); at 20°C mean survival time was 28 days. Fecundity and mortality of borer stages in berries was studied for a range of humidities at 25°C. Maximum fecundity was obtained at 90 and 93.5% RH. Immature stages were ejected from the berry at 84% RH and above, which is interpreted as a form of brood hygiene.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 255-263 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; Leptinotarsa decemlineata ; behavior ; thermal biology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In short-term field trials at combinations of ambient temperature (°C) and insolation (W·m−2), larval Colorado potato beetles (Leptinotarsa decemlineata [Say] [Coleoptera: Chrysomelidae]) were observed after their release on the adaxial surface of leaflets on potato plants (Solanum tuberosum L. Solanaceae). The larvae either began feeding or moved under the leaflet; mean interval from release to expression of these behaviors (2.9±0.05 min [n =358]) was independent of air temperature and insolation. Proportion of larvae moving under the leaflet increased logistically with both air temperature and insolation. A 1 W·m−2 change in insolation (P) evoked the same effect on this proportion as a 0.0838 °C change in air temperature (T a ), so the two quantities were combined as T*=T a +P·0.0838 °C/(W·m−2), which has units of °C. The proportion of larvae moving under the leaflet increased logistically with T*. In 1-day field trials we monitored air temperature, insolation and proportion of larvae under the leaflet, and compared the latter to predictions from the logistic regression derived from the short-term trials. Consistently more larvae occurred under leaflets than predicted from the logistic regression; this bias diminished as T* increased until at T*≥40 °C, observed and predicted proportions were equal. This pattern of deviation from the predictions of the logistic regression is consistent with a thermoregulatory strategy in which larvae move away from hostile conditions, rather than seek optimal conditions.
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  • 3
    Electronic Resource
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    Springer
    Entomologia experimentalis et applicata 69 (1993), S. 13-20 
    ISSN: 1570-7458
    Keywords: Artificial diets ; Coccinellidae ; rearing ; biological control ; Chilocorus spp. ; Coleoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Promising diets were screened and the most successful modified with additives used in artificial diets for other entomophagous insects. Two suitable diets were obtained, one for adults and one for larvae ofChilocorus nigritus (Fabricius) (Coleoptera: Coccinellidae). They were still inferior to natural prey and not adequate as the sole food source for rearing consecutive generations. They are valuable as substitute food in the insectary during shortages of natural prey. Oleander scaleAspidiotus nerii Bouché andAsterolecanium miliaris (Boisduval) were evaluated as natural prey forC. nigritus and two other potential biocontrol agents in southern Africa,C. bipustulatus (Linnaeus) andC. infernalis Mulsant.A. nerii andA. miliaris were suitable for all life stages ofC. nigritus and adults ofC. bipustulatus andC. infernalis. A. miliaris was inadequate for larvae ofC. bipustulatus andC. infernalis.
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  • 4
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    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 177-180 
    ISSN: 1570-7458
    Keywords: aflatoxin ; Carophilus ; Zea mays ; corn ; plant resistance ; Coleoptera ; Nitidulidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 5
    Electronic Resource
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    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 17-23 
    ISSN: 1570-7458
    Keywords: plant varietal resistance ; armyworm ; Spodoptera exempta ; leaf extracts ; Zea mays ; feeding deterrent ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maize (Zea mays L.) leaf tissue of cv Bastille and cv Michoacan 12 was extracted with n-hexane. The extracts were bioassayed against 5th instar African armyworm,Spodoptera exempta (Walker)(Lepidoptera: Noctuidae), by feeding the larvae on agar based media or sucrose impregnated glass fibre discs. The hexane extract of the ‘resistant’ cv Bastille exhibited feeding deterrency and toxicity which were not shown by the ‘susceptible’ cv Michoacan 12. The hexane extract of cv Bastille was adsorbed onto silica gel, the solution filtered off and the adsorbed component taken up into ethyl acetate. Bioassay of these fractions indicated that the toxic and deterrent action was retained in the ethyl acetate fraction. Preparative thin layer chromatography of the ethyl acetate fraction isolated two biologically active constituents. These were both growth inhibitors and lethal by ingestion to the 5th instar African armyworm. Implications for resistance in maize varieties to insect pests are discussed.
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  • 6
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    Entomologia experimentalis et applicata 63 (1992), S. 115-121 
    ISSN: 1570-7458
    Keywords: Pea weevil ; Bruchus pisorum ; Bruchidae ; Coleoptera ; flower feeding ; nectar robbing ; pea ; Pisum sativum ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pea flower feeding by adult pea weevils, Bruchus pisorum (L.) (Coleoptera: Bruchidae), with special emphasis on nectar feeding, was investigated in a series of laboratory experiments. Male and female adults robbed nectar from flowers of the garden and field pea, Pisum sativum L., and females which fed on the nectar, petals, and female organs of pea flowers lived significantly longer than those denied food and water and those that fed on water only. The results of other experiments suggested that pea flower qualities other than pollen influenced the reproductive success of female B. pisorum. It is hypothesized that pollen seeking B. pisorum effected cross-pollination in the wild progenitor of the modern-day autogamous pea, and adult pea weevils of both sexes rob pea nectar to obtain a readily available source of energy to sustain flight.
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  • 7
    ISSN: 1570-7458
    Keywords: Ceutorhynchus inaffectatus ; Coleoptera ; Curculionidae ; Hesperis matronalis ; Dame's violet ; Brassicaceae ; Cruciferae ; glucosinolates ; feeding stimulants ; host plant specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ceutorhynchus inaffectatus Gyllenhal (Coleoptera: Curculionidae:Ceutorhynchinae) is a monophagous species feeding only onHesperis matronalis L. (Cruciferae) in North-western Europe. Feeding responses of this weevil to five glucosinolates from its host plant were compared with the responses to four glucosinolates from non-host plants. The major glucosinolates in the host plant were isolated and identified: 6-methylsulphinylhexylglucosinolate (glucohesperalin), 3,4-dihydroxybenzylglucosinolate (glucomatronalin), 3-O-apiosylglucomatronalin, a 3,4-dihydroxybenzoylester and a 3,4-dimethoxybenzoylester of 3-O-apiosylglucomatronalin. The three glucosinolates containing apiose were powerful feeding stimulants forC. inaffectatus while the other host plant compounds and allyglucosinolate (sinigrin), 3-methylsulphinylpropylglucosinolate (glucoiberin), benzylglucosinolate (glucotropaeolin) and p-hydroxybenzylglucosinolate (sinalbin) were weaker stimulants. The role of glucosinolates in host plant selection ofC. inaffectatus and related monophagous crucifer feeders is discussed.
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  • 8
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    Entomologia experimentalis et applicata 70 (1994), S. 217-225 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; Leptinotarsa decemlineata ; Colorado potato beetle ; Solanaceae ; Solanum berthaultii ; plant resistance ; glandular trichomes ; host preference ; behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Choice and no-choice studies were conducted to determine how the glandular trichomes of the wild potato,Solanum berthaultii Hawkes, affect host preference of the Colorado potato beetle,Leptinotarsa decemlineata (Say). Given a feeding choice betweenS. tuberosum andS. berthaultii, larvae and adults preferred the foliage ofS. tuberosum, but adults were more discriminating. When foliage ofS. berthaultii was appressed toS. tuberosum leaflets, fewer adults fed on the appressed leaflets. When given a choice between ‘trichome-intact’ and ‘trichome-removed’S. berthaultii foliage, adults preferred to feed on the latter. The preference for ‘trichome-removed’ foliage and the percent of adults initiating feeding, increased with the degree of trichome removal. These studies provide evidence that the resistance ofS. berthaultii is associated with feeding deterrents localized in the glandular trichomes, thatS. berthaultii possesses more than one mechanism of resistance to the Colorado potato beetle, and that the expression of resistance is dependent on the developmental stage of the insect.
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  • 9
    Electronic Resource
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    Entomologia experimentalis et applicata 63 (1992), S. 81-86 
    ISSN: 1570-7458
    Keywords: Laboratory bioassay ; olfactometer ; olive bark beetle ; Phloeotribus scarabaeoides ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bioassay conditions with a glass olfactometer for the olive bark beetle, Phloeotribus scarabaeoides Bern. (Coleoptera: Scolytidae), have been investigated. The best temperatures and light intensities were between 17 and 28° C and 1000 and 1500 lux, respectively. The best response was obtained with newly emerged individuals from reproduction galleries with no feeding period.
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  • 10
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    Entomologia experimentalis et applicata 65 (1992), S. 129-140 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Carabidae ; Bembidion lampros ; Pterostichus cupreus ; P. melanarius ; diet ; egg production ; egg size variation ; pirimicarb ; fat reserves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Egg size was measured at different rates of egg laying in three polyphagous carabid species, known to be useful predators of cereal aphids; the small Bembidion lampros Herbst and the medium-sized Pterostichus cupreus L. and P. melanarius Illiger. Variations in fecundity, as well as the ability of the medium-sized species to also build up fat reserves, were obtained when beetles were subjected to different dietary regimes consisting of aphids, or foods with a lower or higher protein content. Egg size was found to be dependent on the rate of egg laying within a species. A diet of cereal aphids appeared to be adequate for egg production in these polyphagous carabids, but female P. cupreus were unable to build up fat reserves when they ingested aphids contaminated with the aphicide pirimicarb. Beetles were able to devote resources to more and larger eggs (B. lampros), or to larger eggs and/or fat reserves (P. melanarius/P. cupreus) when given access to a carbohydrate-rich food with low protein content. The highest rate of egg laying was obtained when female P. cupreus and P. melanarius were given a more varied diet at frequent intervals; including regular shifts between unsprayed aphids, carbohydrate-rich food and protein-rich maggots. Within the varied diet treatment a negative relationship was obtained between egg size and egg number among similar-sized individuals of P. cupreus and P. melanarius; females producing the largest number also laid the smallest eggs. Egg size affected larval survival, since first instars hatching from large eggs were found to survive longer than those hatching from small eggs. The influence of differences in food intake on reproduction, maintenance metabolism, and survival of fieldinhabiting carabids is discussed.
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  • 11
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    Entomologia experimentalis et applicata 65 (1992), S. 235-240 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Tenebrionidae ; Pterohelaeus darlingensis ; Gonocephalum macleayi ; false wireworms ; sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Counts of adults of the false wirewormsGonocephalum macleayi (Blackburn) andPterohelaeus darlingensis Carter in pitfall traps in burnt, mulched and sorghum treatments conformed to Taylor's power law. Within a species there were no significant differences in distributions of counts of either sex in any habitat butG. macleayi were more aggregated thanP. darlingensis (Taylor'sb 1.35 and 1.26, respectively). Relationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines for sequential sampling are developed for each species using Taylor's parameters for combined data over all habitats.
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  • 12
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    Entomologia experimentalis et applicata 65 (1992), S. 247-257 
    ISSN: 1570-7458
    Keywords: Population genetics ; microgeographic differentiation ; leaf-beetles ; Chrysomelinae ; Coleoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We usedF-statistics to quantify the population structure of two sympatric species of leaf beetles,Oreina cacaliae andO. speciosissima (Chrysomelinae, Coleoptera), which share the same microhabitat since they feed on the same herbaceous host plants. We measured genetic differentiation at six allozyme loci 1) among populations separated by relatively small distances (40 to 250 kilometers), 2) within each population, and 3) between sexes within populations. For both species, the populations studied are not panmictic. For each population, heterozygosities are relatively high, but the observed heterozygosities are generally lower than the expected values. Overall, within-population differentiation is high and similar for both species (F is=0.326 forO. cacaliae and 0.332 forO. speciosissima). Additionally, populations of both species are highly differentiated (F st=0.234 versus 0.051 forO. speciosissima). ForO. cacaliae,F is andF st are greater among females than among males, while forO. speciosissima,F st is sustantially greater among the males whileF is is slightly greater among males. Differences in gene frequency among the sexes were statistically tested using a modifiedF st with sex as the defining category, and the sexes differed significantly with the exception of one population inO. cacaliae. Possible explanations for this difference are discussed.
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  • 13
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    Entomologia experimentalis et applicata 66 (1993), S. 161-169 
    ISSN: 1570-7458
    Keywords: avoidance behaviour ; capture efficiency ; Coleoptera ; time-lapse video ; visual recording
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pitfall trap capture forSitophilus oryzae (L.),S. zeamais (Motschulsky),S. granarius (L.),Tribolium confusum (Duval),T. castaneum (Herbst);Oryzaephilus surinamensis (L.),Cryptolestes pusillus (Schonherr),Rhyzopertha dominica (Fabr.), andProstephanus truncatus (Horn) in millet was assessed by visual and time-lapse video recordings. The behaviour of different beetle species in arenas containing millet was monitored over 24 h and the frequency of encounters with the trap rim resulting in capture recorded. The capture efficiency of four types of pitfall traps (i.e. polystyrene, polythene, glass and tin-plated steel can) with rims exposed or submerged below the millet surface level were compared. Capture was related to beetle size, locomotory rate, and beetle behaviour at the trap rim as well as trap design and placement. The lighter and smaller species were least captured. Glass jars were more effective than plastic and metal containers. Traps placed with their rims submerged below the grain surface level were more efficient than those with rims exposed. Capture rate was unrelated to trap size. The frequency of encounters with trap rims was not correlated with capture rate. Three types of avoidance behaviours at the trap rims i.e. probing, skirting and spontaneous retreat, were related to capture rate, spontaneous retreat being the most effective escape mechanism and probing least.
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  • 14
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    Entomologia experimentalis et applicata 65 (1992), S. 39-47 
    ISSN: 1570-7458
    Keywords: Development ; fecundity ; geographical variation ; Coleoptera ; Bruchidae ; ecology ; Phaseolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zabrotes subfasciatus (Boheman) (Coleoptera:Bruchidae) is native to parts of Central and South America but has now been spread to many others areas. It commonly infests the seeds of both Lima beans, Phaseolus lunatus, and common beans, Phaseolus vulgaris. Five geographic populations were found to differ in fecundity, patterns of egg distribution, times of development and adult sizes when they were kept under the same conditions. Each population also differed unpredictably from the others in its response to different cultivars of host seed. These differences have been shown to be of considerable importance in determining the potential pest status of the populations and should also promote caution in making predictions about the responses of different populations to new cultivars of bean for agricultural use.
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  • 15
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    Entomologia experimentalis et applicata 66 (1993), S. 191-196 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata (Say) ; Coleoptera ; Chrysomelidae ; distribution ; diapause ; overwintering ; mortality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 16
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    Entomologia experimentalis et applicata 70 (1994), S. 201-208 
    ISSN: 1570-7458
    Keywords: Sitophilus oryzae ; S. zeamais ; Coleoptera ; Curculionidae ; flight activity ; symbiosis ; vitamin ; amino acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les performances de vol de nombreuses souches deSitophilus oryzae L. etS. zeamais Mots. (Coleoptera, Curculionidae) ont été comparées sur blé. Il s’avère que les mâles sont plus actifs que les femelles et queS. zeamais possède une meilleure aptitude au vol queS. oryzae. De plus, dans les deux espèces élevées sur blé, seuls les charançons normalement symbiotiques sont capables de voler, tandis que les aposymbiotiques ont perdu ce pouvoir. En complémentant la nourriture avec des vitamines (acide pantothénique et riboflavine) et certains acides aminés (phénylalanine et proline), cette activité a pu être restaurée en partie. L’influence de la symbiose sur l’aptitude au vol du charançon du genreSitophilus est commentée en fonction du métabolisme énergétique (coenzymes, proline) et du rôle joué par la symbiose dans ce comportement qui permet d’augmenter la dissémination de l’espèce.
    Notes: Abstract The flight activity (take-off) of various strains ofSitophilus oryzae L. andS. zeamais Mots. (Coleoptera, Curculionidae) have been compared on wheat. It was shown that males are more active than females and thatS. zeamais, is more active thanS. oryzae. Furthermore, in the two species, when reared on wheat kernels, only symbiotic weevils were able to fly, while aposymbiotic insects did not. By supplementation of the diet with vitamins (pantothenic acid, riboflavin) and amino acids (phenylalanine and proline), this activity could be restored in part. The influence of symbiosis on the flight ability ofSitophilus weevil is discussed in relation to the energy metabolism (coenzymes, proline), the role played by symbiosis in this behaviour and its possible effect on the dissemination of the species.
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  • 17
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    Entomologia experimentalis et applicata 73 (1994), S. 39-50 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata ; Coleoptera ; Chrysomelidae ; distribution ; overwintering ; diapause ; cultural control ; trap cropping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Overwintering Colorado potato beetles (Leptinotarsa decemlineata (Say)) were concentrated primarily within woody borders, and mortality was lower in borders than in potato fields. After overwintering, only 15–44% of live beetles were in the potato fields. In experiments with small plots, colonization of fields from woody borders was reduced ∼60% by a trap crop, either treated with adulticide or with beetles collected daily. Such trap crops, or simply pitfall traps to prevent colonization from woody borders, could significantly reduce early-season adult numbers and subsequent larval populations. However, success is dependent on the local densities of overwintered beetles, and the prevalence of arrestment behavior in the case of trap crops.
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  • 18
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; Leptinotarsa decemlineata ; Colorado potato beetle ; Solanaceae ; Solanum berthaultii ; potato ; plant resistance ; selection ; adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thirty cohorts of the Colorado potato beetle (CPB) were reared for ten consecutive generations on the cultivated potato,Solanum tuberosum, and on two accessions (PI 473331 and PI 473334) of the resistant wild species,S. berthaultii. At each generation, selection was imposed for increased survival, decreased development time, and for increased fecundity. Although several parameters responded to selection, net replacement rate (R0) onS. berthaultii was consistently less than 1/3 that on cultivated potato. At the tenth generation, eachS. tuberosum strain female replaced herself with 110 daughters, whereas females from strains reared on PI 473334 and PI 473331 produced an average of 30 and 7 daughters, respectively. Slopes of the R0 regression lines for populations reared onS. tuberosum andS. berthaultii did not differ from zero, indicating no significant response to selection. Our findings suggest that populations of the Colorado potato beetle may have genetic variability in some performance traits for adaptation toS. berthaultii, but that adaptation is unlikely to occur as rapidly as previously reported.
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  • 19
    ISSN: 1572-8889
    Keywords: firefly ; entrainment ; insect communication ; Coleoptera ; aggressive mimicry ; bioluminescence ; Lampyridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract FemalePhoturis versicolor fireflies attempt to capture males by responding to heterospecific flash patterns. A mating-dependent switch occurs which affects response timing and frequency of female flashes. We examined the switch using females of known age, mating status, and flash experience to assess how accurate mimicry is, what factors influence it, and what mechanism produces it. Presentations of simulated male flash patterns before and after mating revealed elements of an entrainment mechanism controlling female responsiveness. Unmated females preferentially answered conspecific patterns with variable latencies, averaging 1 s. Mating induced changes in both response frequency and response latency: Females answered heterospecific patterns more frequently, and latencies elicited by conspecific patterns shifted away from the unmated range. Heterogeneity in mean and variance of response latency among individuals indicates that females do not share a discrete reply to a given pattern. Little correspondence exists between latencies of sympatric species andP. versicolor females, suggesting that the flash response mechanism produces entriainment to any rhythmic pattern, not a one-to-one matching between prey and predator latencies. Different selective scenarios underlie strict mimicry versus entrainment mimicry.
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  • 20
    ISSN: 1572-8889
    Keywords: Coleoptera ; Scarabaeidae ; Cotinis nitida (L.) ; beetle flight ; pheromone bioassay
    Source: Springer Online Journal Archives 1860-2000
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  • 21
    ISSN: 1572-8773
    Keywords: catalase ; copper resistance ; pH-dependent growth ; Saccharomyces cerevisiae ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A strain of Saccharomyces cerevisiae has been adapted to increasing concentrations of copper at two different pH values. The growth curve at pH 5.5 is characterized by a time generation increasing with the amount of added copper. A significant decrease of cell volume as compared with the control is also observed. At pH 3 the cells grow faster than at pH 5.5 and resist higher copper concentrations (3.8 against 1.2 mm). Experimental evidence indicates that, after copper treatment, the metal is not bound to the cell wall, but is localized intracellularly. A significant precipitation of copper salts in the medium was observed only at pH 5.5. Increased levels of superoxide dismutase (SOD) activity were observed in copper-treated cells and which persisted after 20 subsequent inocula in a medium without added metal. On the contrary, catalase activity was not stimulated by copper treatment and, hence, not correlated with SOD levels. The mechanism of copper resistance, therefore, probably involves a persistent induction of SOD, but not of catalase, and it is strongly pH-dependent.
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  • 22
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    Entomologia experimentalis et applicata 59 (1991), S. 75-78 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata Say ; Coleoptera ; Chrysomelidae ; female sex pheromone ; screening method ; mating behaviour ; tactile stimuli
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  • 23
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    Entomologia experimentalis et applicata 54 (1990), S. 219-224 
    ISSN: 1570-7458
    Keywords: Diabrotica virgifera virgifera ; Coleoptera ; Chrysomelidae ; corn ; life-stage occurrence ; planting date
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Dans les conditions de l'est du Sud Dakota (USA), 3 dates de semailles de maïs et 3 dates de contamination avec des œufs de D. virgifera virgifera LeConte ont servi à imposer ou à empêcher la synchronisation des éclosions des œufs et par conséquent des développements ultérieurs. Les dates médianes d'apparition de chacun des 3 stades larvaires et des imagos ont été déterminées en relation avec les unités de température et le nombre de jours depuis la contamination. Aucune différence significative entre les dates médianes d'apparition n'a été mise en évidence par utilisation des unités de température; par contre, ces différences deviennent significatives lorsque l'on utilise le nombre de jours depuis la contamination. Des paramètres fiables sont nécessaires pour prédire la présence des différentes stades de cet insecte. En dépit des différentes conditions imposées pour cette étude, la méthode la moins capricieuse pour prédire l'apparition d'un stade larvaire et l'émergence des adultes est la somme de températures avec une base de 11°C.
    Notes: Abstract Under field conditions in eastern South Dakota, USA three different planting dates of corn and three times of egg infestation were used to imposed synchronous and asynchronous timing of corn growth and Diabrotica virgifera virgifera LeConte egg hatch and subsequent development. Median occurrence of each of the three larval stages and of the adult stage for each of the infestation-planting treatments was determined by relating occurrence to thermal units and to days after infestation. No significant differences were found among the treatments for median occurrence of each life stage when the thermal unit approach was used. However, significant differences were found among treatments for median occurrence when the day after infestation approach was used. Consistent parameters are needed for prediction of the occurrence of life stages of this insect. Despite the various imposed conditions, this study indicates that the least variable method of predicting life stage occurrence and adult emergence of D. v. virgifera was the use of thermal unit accumulations (base 11°C).
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  • 24
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    Entomologia experimentalis et applicata 68 (1993), S. 9-13 
    ISSN: 1570-7458
    Keywords: bioassay ; behavioural response ; Coleoptera ; carob extract ; stored product
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The behavioural responses ofCryptolestes pusillus Oryzaephilus surinamensis andProstephanus truncatus to different doses of carob extract were assessed in a two-choice pitfall bioassay and in plastic grain probe traps. The extract evoked a quick directional response and induced high beetle attraction to treated pitfall arenas compared with the controls. Overall, the extract improved probe trap efficiency by about 50% compared to unbaited probes. Beetle response was dose-dependent with the medium dose of 10 μl probably eliciting optimum response.
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    Cellular and molecular life sciences 46 (1990), S. 700-704 
    ISSN: 1420-9071
    Keywords: Coleoptera ; Tenebrionidae ; Tribolium confusum ; defesive secretion ; biosynthesis of 1-alkenes ; oxidative decarboxylation ; anti-elimination
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    Topics: Biology , Medicine
    Notes: Summary The terminally unsaturated hydrocarbons of the defensive secretion ofTribolium confusum are biosynthesized from fatty acids by oxidative decarboxylation. The process involves an enantiospecific cleavage of the C−H bond of thepro-(S) C(3)−H atom and simultaneous decarboxylation of the acid into an 1-alkene and carbon dioxide via ananti-periplanar transition state geometry (anti-elimination). The stereochemistry of this biotranformation is identical in all respects with the same reaction in higher plants. The mechanism seems to be of general importance for the biosynthesis of many vinylic substructures of natural products from oxygen-containing precursors.
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    Cellular and molecular life sciences 49 (1993), S. 171-174 
    ISSN: 1420-9071
    Keywords: Coleoptera ; Meloidae ; Epicauta funebris ; chemical defense ; biosynthesis ; terpenoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Cantharidin, a potent defensive chemical, is present in all ten life stages of the blister beetleEpicauta funebris. The first five larval stages accumulate cantharidin as they feed and grow in size. When disturbed, they exude cantharidin in a milky oral fluid, not in hemolymph which adult beetles reflexively discharge from leg joints. Two subsequent larval stages and the pupa do not feed, grow, regurgitate, or change in their defensive reserves (110 μg cantharidin/insect, regardless of sex). Adult beetles kept in isolation for 60–90 d exhibit a pronounced sexual dimorphism in cantharidin production: the male biosynthesizes about 17 mg of the toxin, representing 10% of his live weight, whereas the female actually loses most of her defensive reserves. But in the wild a female beetle repeatedly acquires cantharidin as copulatory gifts from her mates.
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    Cellular and molecular life sciences 49 (1993), S. 272-275 
    ISSN: 1420-9071
    Keywords: Semiochemical ; pheromone ; host selection ; competition ; Coleoptera ; Scolytidae
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    Topics: Biology , Medicine
    Notes: Abstract Bark beetles,Ips typographus andPityogenes chalcographus, attracted by synthetic or natural pheromone to Norway spruce logs,Picea abies, preferred to colonize uninfested logs rather than logs occupied by these beetles, probably as a means of avoiding intra-and interspecific competition. The aggregation pheromone components ofP. chalcographus, chalcogran and methyl (E, Z)-2,4-decadienoate, inhibited the attraction response ofI. typographus to its pheromone components (methyl butenol andcis-verbenol), while the converse was not true. However, verbenone released from colonized bark inhibited pheromonal response ofP. chalcographus.
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  • 28
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    Cellular and molecular life sciences 48 (1992), S. 1162-1164 
    ISSN: 1420-9071
    Keywords: Polygodial ; warburganal ; antifungal activity ; Candida albicans ; Saccharomyces cerevisiae ; Pityrosporum ovale ; enhancing effect ; antioxidants ; vitamin C ; BHA ; anethole
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    Topics: Biology , Medicine
    Notes: Abstract The antifungal activity of two drimane sesquiterpene dialdehydes, polygodial (1) and warburganal (2), alone and in combination with several other substances, was examined against three fungi,Candida albicans, Saccharomyces cerevisiae andPityrosporum ovale employing a broth dilution method. Anethole significantly synergized the activity of the two sesquiterpenoids againstC. albicans andS. cerevisiae however, it had only an, additive effect againstP. ovale. By contrast, two antioxidants, ascorbic acid (vitamin C) and BHA (butylated hydroxyanisole), noticeably enhanced the activity of the sesquiterpenoids againstP. ovale, but had no, effect againstC. albicans andS. cerevisiae.
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  • 29
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    Entomologia experimentalis et applicata 54 (1990), S. 29-36 
    ISSN: 1570-7458
    Keywords: Zea mays ; corn ; host plant resistance ; phenolics ; flavonoids ; hydroxamic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les réactions de larves et adultes du nitidulidé C. hemipterus (L.), vecteur de champignons produisant la mycotoxine, aux composés phénoliques caractéristiques, aux flavonoïdes et aux acides hydroxamiques, métabolites secondaires qui provoquent la résistance du maïs (Zea mays L.) ont été examinées au cours d'expériences avec et sans choix. L'alimentation des adultes et des larves est généralement réduite par les acides coumarique et férulique et par la 6-méthoxy-2-benzoxazolinone dans des expériences sans choix; les insectes évitent généralement les aliments qui contiennent ces produits. Quoi qu'il en soit, les larves préfèrent consommer d'autres aliments contenant les autres phénoliques ou flavonoïdes examinés. Les adultes sont plus inconstants dans leur choix alimentaires, mais préfèrent souvent des aliments contenant de la quercetine. Ainsi, des programmes de sélection orientés contre les principaux ravageurs comme Heliothis zea (Boddie) ou Ostrinia nubilalis (Hübner), impliquant la sélection de plantes à teneur élevée en acides phénolique ou hydroxamique, augmentant probablement aussi la résistance aux nitidulidés.
    Notes: Abstract Selected secondary metabolites produced by maize (Zea mays L.) were tested for effects on larvae and adults of the dried-fruit beetle [Carpophilus hemipterus (L.)] in no-choice and choice assays. Feeding by adults and larvae was significantly reduced by ferulic acid and 6-methoxy-2-benzoxazolinone (MBOA) in no-choice assays. In choice assays, larvae and adults generally preferred diets with trans-cinnamic acid, quercetin, rutin, and thymol, but were repelled by diets with either ferulic acid or MBOA.
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    Entomologia experimentalis et applicata 56 (1990), S. 15-21 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; corn rootworms ; age-specific survival ; age-specific fecundity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé D. virgifera virgifera LeConte a été placé sur des régimes nutritifs mimant l'évolution des tissus du maïs disponsibles dans le champ lorsque les insectes éclosent est aux stades suivants du maïs: 1) après émergence de l'épi mâle, mais avant l'apparition des barbes et l'émission du pollen; 2) lors de la présence de barbes et de l'émission de pollen; 3) après la pollinisation et quand les barbes ont bruni. Un quatrième régime a été fourni pendant toute l'expérience comprenant des barbes vertes, du pollen et des feuilles. Les pontes moyennes des femelles pendant les 12 semaines de l'étude on été 125, 235, 179 et 441 pour les régimes 1, 2, 3 et 4. Les dates de mort de la moitié des adultes a été 7,2, 7,2, 6,7 et 8,8 semaines pour respectivement les mêmes régimes. Les femelles du régime 1 pondent à un âge plus avancé que les femelles des régimes 2 et 3. L'influence des changements de la qualité alimentaire du maïs au fur et à mesure du vieillissement des plantes et deDiabrotica, a été déterminée par la survie au bout de 48 heures d'insectes éclos depuis peu et d'autres maintenus en cage sur des lots de maïs à différents stades poussant en serre depuis des temps plus ou moins longs. Plus les plantes sont âgées, plus la survie des 2 groupes deDiabrotica diminue, mais plus vite chez les lots d'insectes âgés.
    Notes: Abstract Adult corn rootworm beetles,Diabrotica virgifera virgifera LeConte, were maintained on three dietary regimes which mimicked the progression of corn tissues that would be available in the field for beetles eclosing when corn was in the following growth stages: (A) after tassels had emerged but prior to silking and pollen shed; (B) while plants were silking and shedding pollen; and (C) after pollination was complete and silks had turned brown. A fourth regime (D) was established in which green corn silks, pollen, and leaves were provided throughout the study. The mean number of eggs laid per female over the 12-week duration of the study was 125, 235, 179, and 441 for regimes A, B, C, and D, respectively. Median length of life was 7.2, 7.2, 6.7, and 8.8 weeks for regimes A, B, C, and D respectively. Beetles in regime A laid a greater proportion of their eggs at an older age than did beetles from regimes B and C. To further investigate the influences on survival of changes in food quality of corn as plants and beetles aged, newly-eclosed beetles and beetles that had been maintained in caged plots of corn growing in a greenhouse for various lengths of time were caged on corn at different stages of growth, and the proportion of beetles surviving for 48 h was determined. Survival decreased as plants aged for both groups of beetles, but decreased at a faster rate for old than for young beetles.
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    Entomologia experimentalis et applicata 61 (1991), S. 255-263 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Bruchidae ; Bruchidius atrolineatus ; larval crowding ; post-embryonic development ; intracotyledonary mortality ; weight of emerging adults ; reproductive diapause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Chez Bruchidius atrolineatus, l'accroissement de la densité larvaire à l'intérieur de la graine entraîne une augmentation de la mortalité alors que la réduction de poids des individus à l'émergence est relativement limitée. L'accroissement de la densité larvaire provoque une augmentation du taux d'adultes en diapause reproductrice, dans certaines conditions thermopériodiques. Dans d'autres conditions, permenttant l'émergence d'un fort taux d'adultes diapausants, l'effet de la densité larvaire est nul. Lorsque l'on analyse l'effet de la densité chez les individus d'une souche ne présentant pas de phénomène de diapause, il n'y a pas de corrélation entre la durée de développement et le poids des adultes. Par contre, lorsqu'il y a émergence d'adultes sexuellement actifs et diapausants, il existe une corrélation entre la durée de développement et le poids des adultes émergeants. Cette corrélation est due au fait que les adultes diapausants, qui présentent les durées de développement les plus longues, sont ceux qui ont les poids les plus faibles.
    Notes: Abstract In Bruschidius atrolineatus (Pic), an increase in larval density inside the seed led to a reduction in the survival rate during post-embryonic development, with only a limited decrease in the weight of adults. A high larval density increased the proportion of adults in reproductive diapause under certain thermoperiodic conditions. Under other conditions that already promote the emergence of a high proportion of diapausing beetles, an increase in larval density had no effect on diapause. There was no correlation between the larval developmental time and the weights of adults in a strain with a very low incidence of diapause. However, such a correlation was observed when both sexuallyactive and diapausing beetles emerged. This correlation was explained by the longer developmental times and lower weights of diapausing beetles.
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 131-135 
    ISSN: 1476-5535
    Keywords: Saccharomyces cerevisiae ; Jerusalem artichoke ; High-fructose syrup ; Ethanol ; Immobilized yeast cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The results from this study showed that Jerusalem artichoke juice can be used for the production of very enriched fructose syrup by selective conversion of glucose to ethanol in a continuous process using immobilized cells ofSaccharomyces cerevisiae ATCC 36859. The product contained up to 99% of the total carbohydrates as fructose compared to 76% in the feed. Using Jerusalem artichoke juice supplemented with some glucose a product was obtained with 7.5% w/v ethanol which made ethanol recovery economically favourable. It was found that some fructose was consumed in these continuous processes; the glucose/fructose conversion rate ratio was regulated by the glucose concentration in the product stream.
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 181-189 
    ISSN: 1476-5535
    Keywords: Saccharomyces cerevisiae ; Torulaspora delbrueckii ; Aroma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Thirty-three fermentations of Pedro Ximénez grapes, collected in three degrees of ripeness, were carried out by inoculation with three types of inoculum: pure cultures ofSaccharomyces cerevisiae races and ofTorulaspora delbrueckii, indigenous yeasts, and mixed cultures of indigenous yeasts enriched with the pure cultures. By means of variance analysis 21 compounds were determined whose final concentrations in the wines significantly depended on the musts, the inocula or both. Eleven products that depended significantly on the inocula were subjected to a discriminant analysis in which most of the pure cultures gathered in a discriminant space area different from that occupied by the indigenous yeasts. The centroids corresponding to most of the mixed cultures were shifted to the central area of the discriminant space, moved away from their corresponding pure cultures and approached the indigenous yeasts. The results show a high similarity between the fermentations carried out with mixed cultures with the addedS. cerevisiae races and those fermentations carried out with the indigenous yeasts, with regard to those compounds which were significantly dependent on the inocula.
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    Mycorrhiza 5 (1994), S. 119-124 
    ISSN: 1432-1890
    Keywords: Key words Glomus mosseae ; Manganese uptake ; Root exudation ; Manganese reduction ; Mycorrhizal effect ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of rhizosphere microorganisms and vesicular-arbuscular (VA) mycorrhiza on manganese (Mn) uptake in maize (Zea mays L. cv. Tau) plants was studied in pot experiments under controlled environmental conditions. The plants were grown for 7 weeks in sterilized calcareous soil in pots having separate compartments for growth of roots and of VA mycorrhizal fungal hyphae. The soil was left either uninoculated (control) or prior to planting was inoculated with rhizosphere microorganisms only (MO-VA) or with rhizosphere microorganisms together with a VA mycorrhizal fungus [Glomus mosseae (Nicol and Gerd.) Gerdemann and Trappe] (MO+VA). Mycorrhiza treatment did not affect shoot dry weight, but root dry weight was slightly inhibited in the MO+VA and MO-VA treatments compared with the uninoculated control. Concentrations of Mn in shoots decreased in the order MO-VA〉MO+VA〉control. In the rhizosphere soil, the total microbial population was higher in mycorrhizal (MO+VA) than nonmycorrhizal (MO-VA) treatments, but the proportion of Mn-reducing microbial populations was fivefold higher in the nonmycorrhizal treatment, suggesting substantial qualitative changes in rhizosphere microbial populations upon root infection with the mycorrhizal fungi. The most important microbial group taking part in the reduction of Mn was fluorescent Pseudomonas. Mycorrhizal treatment decreased not only the number of Mn reducers but also the release of Mn-solubilizing root exudates, which were collected by percolation from maize plants cultivated in plastic tubes filled with gravel quartz sand. Compared with mycorrhizal plants, the root exudates of nonmycorrhizal plants had two fold higher capacity for reduction of Mn. Therefore, changes in both rhizosphere microbial population and root exudation are probably responsible for the lower acquisition of Mn in mycorrhizal plants.
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    Biology and fertility of soils 18 (1994), S. 228-230 
    ISSN: 1432-0789
    Keywords: Fine root ; Root litter ; Biofertiliser ; Leucaena leucocephala ; Trigonella foenum-graecum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficacy ofLeucaena leucocephala root litter as a natural biological fertiliser was assessed usingZea mays as a test plant. Up to 8% of the fine roots of the plants constituted root litter. This fine root litter was better than that ofTrigonella foenum-graecum at increasing the growth and productivity ofZea mays. The root litter increased the growth of maize shoots more than the growth of roots. This appears to be a general phenomenon when plant nutrients are insufficient, as in the present study.
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  • 36
    ISSN: 1432-0983
    Keywords: 2-oxoglutarate dehydrogenase ; Saccharomyces cerevisiae ; rad52-mediated chromosome loss
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    Topics: Biology
    Notes: Summary Ogd1 mutants of Saccharomyces cerevisiae are deficient in mitochondrial 2-oxoglutarate dehydrogenase activity; they cannot grow on glycerol and produce an increased amount of organic acids during growth on glucose as substrate. Using gamma ray-induced rad52-mediated chromosome loss the ogd1 mutation can be assigned to chromosome IX. Tetrad analysis of crosses between ogd1 and other markers on chromosome IX revealed that the OGD1 gene maps on the left arm of this chromosome 1.9 cM from his5.
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  • 37
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Orotate phosphoribosyl transferase ; Nucleotide sequence-5-phosphoribosyl 1-pyrophosphate (5PRPP)
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    Notes: Summary Orotate phosphoribosyl transferase (OPRTase) catalyses the transformation of orotate to OMP in the pyrimidine pathway. In the yeast Saccharomyces cerevisiae, the URA5 gene is known to encode this enzyme activity. In this paper we present the cloning and sequencing of a yeast gene, named URA10, encoding a second OPRTase enzyme. Comparison of the predicted amino acid sequences between URA5 and URA10 genes shows more than 75% similarity. These sequences have also been compared to those of Escherichia coli, Podospora anserina, Sordaria macrospora and Dictyostelium discoideum. Remarkable similarities in the primary structure of these proteins have been found. Gene disruption experiments revealed that URA10 gene expression is responsible for the leaky phenotype of a ura5 mutant. Assays of OPRTase activity in extracts from ura5 and ura10 mutants indicate that the URA10 product contributes only 20% of the total activity found in wild type cells.
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  • 38
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mutants ; Farnesyl diphosphate synthetase ; Ergosterol
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    Notes: Summary Two yeast mutant strains auxotrophic for ergosterol and blocked in farnesyl diphosphate synthetase (EC 2.5.1.1) were isolated. Genetic analysis has shown that these mutant strains carry additional mutations in the ergosterol pathway besides erg20-1 and erg20-2 which affect FPP synthetase. The novel feature of these mutants is their ability to excrete prenyl alcohols (farnesol and geraniol). As geraniol is toxic for yeast cells, the above leaky mutations in FPP synthetase have to be associated with others in the sterol pathway, in order to slow down geraniol synthesis.
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  • 39
    ISSN: 1432-0983
    Keywords: Glucose oxidase ; Aspergillus ; Saccharomyces cerevisiae
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    Notes: Summary We report the cloning of the Aspergillus niger glucose oxidase gene and its use to elevate glucose oxidase productivity in A. niger by increasing the gene dosage. In addition, the gene has been introduced into A. nidulans where it provides the novel capacity to produce glucose oxidase. A plasmid, in which DNA encoding the mature form of glucose oxidase was preceded by a Saccharomyces cerevisiae secretion signal, effected high-level production of extracellular glucose oxidase in this yeast.
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  • 40
    ISSN: 1432-0983
    Keywords: Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; Argininosuccinate lyase ; Sequence
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary The complete nucleotide sequence of the ARG7 gene, coding for argininosuccinate lyase (EC 4.3.2.1), in the fission yeast (Schizosaccharomyces pombe) has been determined. It consists of an open reading frame of 461 codons. The deduced protein has a molecular weight of 51 200 Da. The gene is devoid of introns which is confirmed by the fact that it is expressed in Escherichia coli after spontaneous insertion of a bacterial sequence probably bearing a prokaryotic promoter. A perfect “TATA” box is found at-72 and the major transcription initiation site in Saccharomyces cerevisiae is located at-11 as shown by primer extension experiments. Comparison of the S. pombe lyase with related proteins from other organisms reveals an important degree of conservation except in the carboxyterminal part of the polypeptide. Additionally, a deletion removing 66 amino acids of the carboxy terminus yields an enzyme exhibiting some biological activity. A unique 1500 b transcript was found in S. cerevisiae when the intact gene was present, but the deleted version of the gene gave rise to at least three transcripts of 1800, 2800 and 3900 b.
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  • 41
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Pyrimidine salvage pathway ; Semi-dominant mutants ; FUR1 ; Uracil phosphoribosyl transferase ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Saccharomyces cerevisiae, the protein encoded by the FUR1 gene is absolutely required for the expression of uracil phosphoribosyl transferase activity. The occurrence of semi-dominant mutations for 5-fluorouracil-(5FU)-resistance at this locus led us to clone and sequence the semi-dominant fur 1–5 allele. A single point mutation, resulting in the substitution of arginine 134 for serine, is responsible for this mutant phenotype. The fur 1–5 allele is transcribed and expressed at the same level as the wild-type allele. But, in contrast with the wild-type, the UPR Tase activity of the fur 1–5 mutant strain is stimulated in vitro by UTP and does not, therefore, correspond to a loss of feedback of UPR Tase activity. We found that uracil, as a free base, induces a significative increase in transcription and UPR Tase activity in a wild-type strain as well as in uracil-overproducing mutants which principally explains the high efficiency of the pyrimidine salvage pathway in S. cerevisiae.
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    Current genetics 18 (1990), S. 401-403 
    ISSN: 1432-0983
    Keywords: Baking yeast ; Saccharomyces cerevisiae ; Dough leavening ; Benomyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To investigate the leavening ability of yeast in dough, chromosome loss was induced by benomyl treatment in YOY1037, a diploid between a baking strain and a laboratory strain, and its effect on the leavening ability was studied. When benomyl-treated cells were spread on plates with a dye indicator for ploidy, about 20% of the visible colonies were stained dark blue or dark purple; the rest stained pale blue, similar to the diploid YOY1037. Strains showing the MATα phenotype, and non-galactose fermenting strains, apparently having lost particular chromosomes, were observed only in those with darkcoloured colonies. Strains with dark-coloured colonies showed a wider range of leavening ability than did those with pale-coloured colonies.
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  • 43
    ISSN: 1432-0983
    Keywords: Xylitol dehydrogenase gene ; Pichia stipitis ; Saccharomyces cerevisiae ; Xylose utilization
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    Notes: Summary A P. stipitis cDNA library in λgt11 was screened using antisera against P. stipitis xylose reductase and xylitol dehydrogenase, respectively. The resulting cDNA clones served as probes for screening a P. stipitis genomic library. The genomic XYL2 gene was isolated and the nucleotide sequence of the 1089 bp structural gene, and of adjacent non-coding regions, was determined. The XYL2 open-reading frame codes for a protein of 363 amino acids with a predicted molecular mass of 38.5 kDa. The XYL2 gene is actively expressed in S. cerevisiae transformants. S. cerevisiae cells transformed with a plasmid, pRD1, containing both the xylose reductase gene (XYL1) and the xylitol dehydrogenase gene (XYL2), were able to grow on xylose as a sole carbon source. In contrast to aerobic glucose metabolism, S. cerevisiae XYL1-XYL2 transformants utilize xylose almost entirely oxidatively.
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  • 44
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Centromere flanking sequences ; tRNA modification enzymes
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    Notes: Summary Transcriptional analysis of the region flanking the left boundary of the centromere of chromosome VI revealed the presence of a gene immediately adjacent to CEN6. The transcription of the gene is directed toward the centromere, and nucleotide sequence analysis showed that the coding region terminates only 50 bp away from CEN6. Our results extend to chromosome VI the observation that centromere-flanking regions of S. cerevisiae are transcriptionally active. Disruption of the coding region of the gene showed that its product, whilst not essential for cell viability, is important for normal cell growth. The gene has been termed DEG1 (DEpressed Growth rate). Comparison of the deduced amino acid sequence of DEG1 with a protein sequence databank revealed homology with the enzyme tRNA pseudouridine synthase I of E. coli.
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  • 45
    ISSN: 1432-0983
    Keywords: Mutagen hyper-resistance ; Nitrogen mustard ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary A screening of haploid yeast strains for enhanced resistance to nitrogen mustard (HN2) yielded a recessive mutant allele, hnm1, that conferred hyper-resistance (HYR) to HN2. Diploids, homo- or heterozygous for the HNM1 locus, exhibit normal wild-type like resistance while homozygosity for hnm1 leads to the phenotype HYR to HN2. The hnm1 mutation could be found in yeast strains proficient or deficient in different DNA repair systems. In these mostly HN2-sensitive haploid repair-deficient mutants, hnm1 acted as a partial suppressor of HN2 sensitivity. All isolated recessive mutations conferring hyper-resistance belonged to a single complementations group. The HYR to HN2 phenotype was maximally expressed in growing cells and was associated with reduced mutability by HN2. HNM1 most probably controls uptake of HN2 which would be impaired in the hnm1 mutants.
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  • 46
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; G418 resistance ; Gene cartridges ; Heterologous Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Coding sequence cartridges for aminoglycoside phosphotransferase (APT) were isolated from bacterial transposon Tn903. When incorporated into a heterologous gene construction utilising the PGK1 promoter and terminator, the heterologous APT gene provided a G418-resistance determinant that functioned efficiently as a dominant marker for yeast in both multiple- and single-copy. Transformant colonies on selective medium appeared rapidly, within 36–48 h, and growth rate of the transformed cells was normal. A simple and highly sensitive radiolabelling assay for APT enzyme activity was developed for use with crude cell protein extracts. Enzyme activity units were equated to the amount of APT protein present in the cells, and the APT protein was shown to be stable in yeast. Heterologous APT expression was 130-fold reduced compared with homologous PGK1. This resulted from an estimated two-fold decrease in mRNA level and a 65-fold decrease in translation efficiency. The latter was unaffected by AUG sequence context change, but corresponded with a high frequency of minor codons in the APT-coding sequence. APT can be used as a semi-quantitative reporter of gene expression, whose useful features are in vivo detection via the G418-resistance phenotype and powerful cell-free assay.
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  • 47
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    Current genetics 19 (1991), S. 9-14 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mevalonate kinase ; Ergosterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of the ERG12 gene, encoding mevalonate kinase, from Saccharomyces cerevisiae is presented. The longest open reading frame may code for a protein containing 443 amino acids with a deduced relative molecular mass of 48 500. The analysis of the nucleotide sequence reveals a complete identity with the yeast gene RAR1, isolated elsewhere by complementation of a rar1 mutation involved in the stability of plasmids with weak ARS. In addition, we show that mevalonate kinase is not a rate-limiting enzyme; however its sensitivity to FFP could be a key regulatory mechanism in the sterol pathway of yeast.
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  • 48
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Episomal plasmid ; Copy number control ; Plasmid maintenance ; Glycolytic enzyme levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study demonstrates how varying the promoter strength of an essential gene on a yeast 2μORI-STB YEp multicopy vector can influence vector copy levels. A phosphoglycerate kinase gene (PGK) on this plasmid was made essential for fermentative growth by transformation into a pgk - yeast strain. When in these PGK- transformants the requirement for PGK expression was the sole selective criterion for plasmid maintenance, PGK promoter activity was inversely related to vector copy levels. Plasmids with an efficiently-transcribed PGK gene were maintained at approximately one copy per cell, whereas those lacking the UAS that normally directs high basal PGK transcription levels were present at up to 10–15 copies. All cultures of these PGK+ transformants contained only a low proportion of pgk - cells. Since mitotic loss of the plasmid arrests growth through loss of a functional PGK allele, PGK confers high stability to the YEp vector in such a pgk - genetic background. In this system YEp vector levels are probably influenced by PGK transcription because high expression of PGK is needed in rapid fermentative growth. Remarkably, low plasmid PGK promoter activity caused PGK mRNA levels slightly higher than those found in yeast with normal PGK regulation. A higher plasmid copy number is therefore not the only factor counteracting the effects of low PGK transcription, and it is possible that PGK mRNA becomes more stable in response to inefficient PGK transcription.
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  • 49
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Sporulation ; Inessential genes ; Genome organization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The SPR6 gene of Saccharomyces cerevisiae encodes a moderately abundant RNA that is present at high levels only during sporulation. The gene contains a long open reading frame that could encode a hydrophilic protein approximately 21 kDa in size. This protein is probably produced by the yeast, because the lacZ gene of Escherichia coli is expressed during sporulation when fused to SPR6 in the expected reading frame. SPR6 is inessential for sporulation; mutants that lack SPR6 activity sporulate normally and produce viable ascospores. Nonetheless, the SPR6 gene encodes a function that is relevant to sporulating cells; the wild-type allele can enhance sporulation in strains that are defective for several SPR functions. SPR6 is located on chromosome V, 14.4 centimorgans centromere-distal to MET6.
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  • 50
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Nucleo-mitochondrial interactions ; Mitochondrial status ; Lycorine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In a previous paper we have shown that the alkaloid lycorine inhibits growth of rho +, mit - and rho -, strains of Saccharomyces cerevisiae, whereas strains devoid of mitochondrial DNA (rho o) are resistant to more than 200 μg/ml of the alkaloid. In this report we show that hypersuppressive petites are almost as resistant as rho o mutants, whereas isogenic rho - petites, which have retained tained longer segments of the genome, are sensitive to the drug.
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  • 51
    ISSN: 1432-0983
    Keywords: Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; CaMV 35S promoter ; CaMV 35S terminator ; Heterologous expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Complementation of fission yeast mutants by plant genomic libraries could be a promising method for the isolation of novel plant genes. One important prerequisite is the functioning of plant promoters and terminators in Schizosaccharomyces pombe and Saccharomyces cerevisiae. Therefore, we studied the expression of the bacterial β-glucuronidase (GUS) reporter gene under the control of the Cauliflower Mosaic Virus (CaMV) 35S promoter and 35S terminator. We show here that S. pombe initiates transcription at exactly the same start site as was reported for tobacco. The 35S CaMV terminator is appropriately recognized leading to a polyadenylated mRNA of the same size as obtained in plant cells transformed with the same construct. Furthermore, the GUS-mRNA is translated into fully functional GUS protein, as determined by an enzymatic assay. Interestingly, expression of the 35S promoter in the budding yeast S. cerevisiae was found to be only moderate and about hundredfold lower than in S. pombe. To investigate whether different transcript stabilities are responsible for this enormous expression difference in the two yeasts, the 35S promoter was substituted by the ADH (alcohol dehydrogenase) promoter from fission yeast. In contrast to the differential expression pattern of the 35S promoter, the ADH promoter resulted in equally high expression rates in both fission and budding yeast, comparable to the 35S promoter in S. pombe. Since the copy number of the 35S-GUS constructs differs only by a factor of two in the two yeasts, it appears that differential recognition of the 35S promoter is responsible for the different transcription rates.
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  • 52
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mitochondria ; Intron-encoded proteins ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The respiratory competency of a yeast strain devoid of mitchondrial introns is quite normal. However, it may be asked whether intron-encoded proteins participate in metabolisms other than those of mitochondrial introns. Using strains without mitochondrial introns we have answered two questions. The first was: does the absence of intron-encoded proteins abolsh mitochondrial recombination? The second was: do mitochondrial introns and intron-encoded proteins play a part in mitochondrial DNA rearrangements induced by ethidium bromide (rho- production)? We have shown that the introns and intron-encoded proteins are not essential essential components of either phenomenon.
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  • 53
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    Current genetics 18 (1990), S. 23-27 
    ISSN: 1432-0983
    Keywords: Protein translocation ; Saccharomyces cerevisiae ; Peroxisomes ; Overexpression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Import of proteins into organelles usually requires a cis-acting targeting signal. Analysis of various hybrid proteins, consisting of mouse DHFR and parts of catalase A from Saccharomyces cerevisiae, revealed that fusion proteins containing the N-terminal 126 amino acids, or less, of catalase A remain in the cytosol whereas fusion proteins containing 140, or more, N-terminal amino acids of catalase A form large aggregates inside the cell. These protein bodies, which lack a surrounding membrane, copurified with peroxisomes on cell fractionation. The peroxisomal targeting signal of catalase A does not reside at the C-terminus or at the N-terminus.
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  • 54
    ISSN: 1432-0983
    Keywords: Chloroplast DNA ; Junction between small single copy and inverted repeat regions ; Zea mays ; Grammineae ; ndhH gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The junctions JSA and JSB between the two inverted repeat regions IRA and IRB and the small single copy region of the maize chloroplast DNA have been identified by DNA sequencing. The JSA junction coincides with the initiation codon of the ndhH gene which is encoded by the adjacent region of the small single copy region. A comparison with the plastomes of rice, rye, tobacco and liverwort shows that linkage of this junction with the ndhH gene is specific for gramminean species. The amino acid sequences deduced from the ndhH genes show conserved histidine and cysteine residues which are likely to form a metal-binding domain.
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  • 55
    ISSN: 1432-1432
    Keywords: Thiolase ; Peroxisome evolution ; Bootstrap analysis ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The thiolase family is a widespread group of proteins present in prokaryotes and three cellular compartments of eukaryotes. This fact makes this family interesting in order to study the evolutionary process of eukaryotes. Using the sequence of peroxisomal thiolase from Saccharomyces cerevisiae recently obtained by us and the other known thiolase sequences, a phylogenetic analysis has been carried out. It shows that all these proteins derived from a primitive enzyme, present in the common ancestor of eubacteria and eukaryotes, which evolved into different specialized thiolases confined to various cell compartments. The evolutionary tree obtained is compatible with the endosymbiotic theory for the origin of peroxisomes.
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  • 56
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    Journal of molecular evolution 38 (1994), S. 363-368 
    ISSN: 1432-1432
    Keywords: Saccharomyces cerevisiae ; 2-μm circle ; DNA sequencing ; Horizontal transmission ; Site-specific recombination ; Selfish DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the nucleotide substitution pattern over the entire genome of two unique variants of the 6,300-bp selfish DNA (2 μm) plasmid in Saccharomyces cerevisiae. The DNA sequence of the left-unique region is identical among 2-μm variants, while the right-unique region shows substantial divergence. This chimeric pattern cannot be explained by neutral or Darwinian selection models. We propose that horizontal transmission of the 2-μm plasmid coupled with a directed, polarized gene conversion maintains the DNA sequence of the left-unique region, whereas the right-unique region is subject to random drift and Darwinian selection.
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  • 57
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    Mycopathologia 109 (1990), S. 177-182 
    ISSN: 1573-0832
    Keywords: Helminthosporium maydis ; Zea mays ; Green islands/infection sites ; cytokinin activity ; pathogenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Green islands/infection sites recorded higher cytokinin activity than surrounding tissue as well as non-inoculated tissue. This activity in infected areas increased with time of incubation while in tissue surrounding the green islands and non-inoculated tissue, cytokinin activity decreased with time of incubation. The culture filtrate extracts of H. maydis had cytokinin activity which increased with growth of the fungus. Cytokinin activity of thin-layer Chromatographic fractions from tissue and culture filtrate extracts revealed that a major portion of the activity was confined to Rf zone 0.6 to 0.8 which co-chromatographed with zeatin and zeatin riboside. Presence of zeatin and zeatin riboside in tissue and culture filtrates was confirmed by high performance liquid chromatography. Cytokinin substances, such as zeatin and zeatin riboside, increase at infection sites with growth of the pathogen suggesting they may be involved in the pathogenicity of H. maydis on maize.
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  • 58
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    Mycopathologia 117 (1992), S. 157-161 
    ISSN: 1573-0832
    Keywords: Phyllachora maydis ; Monographella maydis ; Coniothyrium phyllachorae ; Zea mays ; tarspot complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The tarspot complex is caused by the interaction of Phyllachora maydis and Monographella maydis. Coniothyrium phyllachorae, possibly a mycoparasite, is found in older ascostromata of P. maydis, which always appears first causing tarspot. M. maydis follows and is responsible for the damaging “fisheye” symptom. The fisheye symptom is always associated with a tarspot in the center of the lesion, whereas 12 to 20% of the Phyllachora ascostromata remained free of M. maydis. Inoculations of maize leaves with the Microdochium anamorph of the Monographella (usually produced in lesions) failed to produce infections. Some infections with M. maydis were, however, obtained under unusual conditions in the field. Inoculations onto tarspots in the laboratory were unsuccessful, but in field experiments inoculations with conidia of M. maydis enhanced severity of the tarspot complex. Fisheye symptoms of the complex naturally appear 2 to 7 days after the manifestation of P. maydis. This is followed a week later by the appearance of M. maydis which became predominant in the lesions and is associated with empty perithecia of P. maydis. In the early stages of the tarspots pycnidia of the anamorph of P. maydis, Linochora sp., could occasionally be observed. Ascomata of M. maydis were rare in the field. Of the 36 genetic materials of CIMMYT tested, 30 developed the fisheye symptom, 4 tarspots only and 2 remained free of symptoms
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  • 59
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    Mycopathologia 119 (1992), S. 181-190 
    ISSN: 1573-0832
    Keywords: aflatoxin B1 ; electron microscopy ; in vitro ; immature maize embryo ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Immature maize (Zea mays L.) embryos were treated with aflatoxin B1 concentrations, ranging from 0.1 μg ml−1 to 25 μg ml−1. Below 5 μg ml−1 aflatoxin B1, root and shoot elongation was not significantly inhibited. Ultrastructurally, root tip cells showed little deterioration, except a possible diffused clearing in mitochondria and plastids. As the toxin concentration was increased above 5 μgml−1, shoot, and particularly root elongation, was progressively inhibited. Associated with this, there was an apparent decrease in the ribosome population. Furthermore, membranes, particularly the vacuolar membrane, became abnormal and vacuolar distension occurred. At 20 and 25 μg ml−1, these effects were exacerbated, and mitochondria and plastid structure was disrupted. At these concentrations, there was evidence of a disruption in lipid metabolism. The results are discussed in the context of known aflatoxin effects on cellular control mechanisms and ultrastructure in animal systems.
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  • 60
    ISSN: 1573-0832
    Keywords: Nystatin ; amphotericin B ; amphotericin B methyl ester ; polyene antibiotics ; yeast ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Saccharomyces cerevisiae was cultured under anaerobiosis in semi-complete medium to which either palmitoleic or oleic acid was added. Cells were grown at 20 °C or 30 °C. The levels of total lipids, total sterols, and phospholipids were higher in cells grown at 20 °C than at 30 °C. The effects of nystatin (NYS), amphotericin B (AMB), and amphotericin B methyl ester (AME) were evaluated by determining cell viability and liberation of intracellular compounds. The loss of cell viability is higher in the first 30 minutes of incubation with the drugs and is the same regardless of the type of cells obtained. Low molecular weight compounds and ions such as K+ are liberated a few minutes after incubation with the drugs whereas proteins and substances absorbing at 260 nm are liberated later. Phosphate liberation comes after K+ and before compounds of higher molecular weights.
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  • 61
    ISSN: 1572-9699
    Keywords: 2-Deoxy-D-glucose transport ; polyphosphate ; Saccharomyces cerevisiae ; sugar phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of polyphosphate in 2-deoxy-D-glucose transport was studied in yeast cells, pulse-labeled with [32P]orthophosphate, by comparing the concentrations and specific activities of polyphosphate, orthophosphate and 2-dGlc-phosphate. When 2-dGlc transport was measured under aerobic conditions, it appeared that polyphosphate replenished the orthophosphate pool, indicating that polyphosphate has, at least mainly, an indirect role in sugar phosphorylation. Also in cells with a reduced respiratory capacity, due to a treatment with antimycin A, no direct role for polyphosphate in 2-dGlc transport could be detected. Under these conditions, only a very limited breakdown of polyphosphate occurred, probably because of the small decrease in the orthophosphate concentration.
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  • 62
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    Antonie van Leeuwenhoek 62 (1992), S. 35-46 
    ISSN: 1572-9699
    Keywords: introns ; pre-mRNA splicing ; RNA processing ; Saccharomyces cerevisiae ; yeast genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The occurrence of introns in nuclear precursor RNAs (pre-mRNAs) is widespread in eukaryotes, and the splicing process that removes them is basically the same in yeasts as it is in higher eukaryotes. Splicing takes place in a very large, multi-component complex, the spliceosome, and biochemical studies have been complicated by the large number of splicing factors involved. This review describes how genetic approaches used to study RNA splicing inSaccharomyces cerevisiae have complemented the biochemical studies and led to rapid advances in the field.
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  • 63
    ISSN: 1423-0445
    Keywords: toxin sequestration ; predation ; human dietary hazard ; cantharidin ; Coleoptera ; Meloidae ; Epicauta vittata ; Rana ; Hirudo ; Nerodia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Frogs(Rana pipiens) fed on blister beetles (Meloidae) or cantharidin, retain cantharidin systemically. After cessation of feeding, they void the compound relatively quickly. Systemic cantharidin does not protect frogs against ectoparasitic feeding by leeches(Hirudo medicinalis) or predation by snakes(Nerodia sipedon). As suggested by our data, and from reports in the early literature, ingestion of cantharidin-containing frogs can pose a health threat to humans.
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  • 64
    ISSN: 1423-0445
    Keywords: pheromone ; attractant ; triene ; tetraene ; hydrocarbon ; Insecta ; Coleoptera ; Nitidulidae ; Carpophilus freemani
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Males ofCarpophilus freemani Dobson (Coleoptera: Nitidulidae) produce an aggregation pheromone to which both sexes fly in a wind-tunnel bioassay. The major pheromone component (ca. 30 ng per male per day in volatile collections) was identified as (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene. A minor component, (2E,4E,6E,8E)-7-ethyl-3,5-dimethyl-2,4,6,8-undecatetraene, was 3–10% as abundant as the major triene and was 5–20% as active when compared at relative doses ranging from natural proportions to 1:1. These compounds act synergistically: a mixture of major and minor components in natural proportions attracted more than twice as many beetles as the major component alone, and the mixture fully accounted for the activity of male-derived volatile collections. Six other male-derived conjugated hydrocarbons, ranging from 2% down to 0.04% as abundant as the major component, were also identified. These are (in order of decreasing bioassay activity when compared on an equal-weight basis): (3E,5E,7E)-6-ethyl-4-methyl-3,5,7-decatriene, (2E,4E,6E)-5-ethyl-3-me-thyl-2,4,6-octatriene, (3E,5E,7E,9E)-8-ethyl-4,6-dimethyl-3, 5,7,9-dodecatetraene, (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6, 8-undecatetraene, (3E,5E,7E)-5-ethyl-7-methyl-3,5,7-undecatriene, and (2E,4E,6E)-3,5-dimethyl-2,4,6-nonatriene. All structure identifications were confirmed by synthesis. In the wind tunnel, the pheromone acted synergistically with “host”-type volatiles such as propyl acetate, valeric acid, and ethanol. This concept was verified by fields tests in California, in which there was dramatic synergism between the pheromone and fermenting host materials. Pheromone biosynthesis is discussed.
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  • 65
    ISSN: 1423-0445
    Keywords: secretion-grooming ; pygidial glands ; chemical defence against microorganisms ; respiration ; aquatic beetles ; Coleoptera ; Hydradephaga ; Gyrinidae ; Haliplidae ; Noteridae ; Hygrobiidae ; Dytiscidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All Hydradephaga investigated so far crawl onto land when exposed to an increase in water temperature and light intensity and spread the secretion from their pygidial glands over the body surface (“secretion-grooming”). The secretions have antimicrobial properties and are mainly applied to hydrofuge body regions important for aquatic respiration. Experimental prevention of secretion-grooming leads to the loss of the respiratory air bubble and a significant increase in mortality. These findings support the view that the secretion-grooming of adephagous aquatic beetles, like in some aquatic Heteroptera, inhibits the growth of microor-ganisms, thus preventing the contamination and wetting of the cuticular respiratory structures. Thus it keeps functional the air-retaining hydrophobous body regions essential for aquatic respiration. A model is presented on how secretion-grooming may have evolved in the Hydradephaga. Other possible functions of the pygidial gland secretions are discussed.
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  • 66
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; coccinelline ; Coleoptera ; Coccinellidae ; Coccinella septempunctata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 7-spot ladybirds secrete alkaloid (coccinelline)-rich fluid (reflex blood) from leg joints as a defence mechanism against predators. A technique is described that enables the collection and accurate quantification of reflex blood produced, and the amount of coccinelline therein. Coccinelline was found distributed throughout the body, although concentrated in the reflex blood. Reflex blood was collected from a large set of beetles at several time points. Significant variation was found among beetles in the amount of reflex blood produced (for males and for females corrected for body weight) and the coccinelline concentration of the reflex blood. The results are discussed in relation to automimicry and the maintenance of variation through energy trade-offs. The relationships between tendency to aggregate, ability to reflex bleed and the possession of aposematic coloration are also considered.
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  • 67
    ISSN: 1423-0445
    Keywords: specificity ; predation ; long-range orientation ; windtunnel ; Coleoptera ; Rhizophagidae ; Scolytidae ; Rhizophagus grandis ; Dendroctonus micans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The predator,Rhizophagus grandis, is linked to its specific prey,Dendroctonus micans, by semiochemical signals regulating oviposition and long range orientation. A mixture of simple oxygenated monoterpenes [(−)—fenchone, (−)—pinocamphone, rac. camphor, terpinene-4-ol, borneol, fenchol and verbenone], identified from the frass ofD. micans has been found to be extremely active in a flight windtunnel as a long—range attractant for the predator. The mixture elicited 84 % of the response to larval frass of the prey. Excluding pinocamphone from the mixture did not influence its activity. Also, changing the absolute configurations of some of the components (fenchol, terpinene-4-ol and borneol) did not influence the predators' response. However, the addition of (−)—α-terpineol increased the attractivity of the synthetic blend to almost that of larval frass of the prey. Ecological implications of the identified semiochemicals and their use in pest management are discussed.
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  • 68
    ISSN: 1423-0445
    Keywords: sequestration ; pharmacophagy ; defense ; allomone ; kairomone ; cucurbitacin ; Cucurbitaceae ; Coleoptera ; Chrysomelidae ; Luperini ; Diabrotica ; Aulacophora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.
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  • 69
    ISSN: 1423-0445
    Keywords: chemical defence ; tri-trophic interactions ; alkaloids ; Homoptera ; Aphis craccivora ; Icerya spp. ; Lepidosaphes ulmi ; Planococcus citri ; Coleoptera ; Coccinellidae ; Cryptolaemus montrouzieri ; Rodolia cardinalis ; Chilocorus bipustulatus ; Neuroptera ; Chrysopidae ; Chrysoperla carnea ; Hymenoptera ; Encyrtidae ; Encyrtus infelix ; Leguminosae ; Erythrina corallodendrum ; Spartium junceum ; Citrus sinensis ; Euphorbia tirucalli ; Pittosporum tobira
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.
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  • 70
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    Chemoecology 4 (1993), S. 29-32 
    ISSN: 1423-0445
    Keywords: chemical defence ; alkaloids ; predation ; Coleoptera ; Coccinellidae ; Adalia bipunctata ; Coccinella septempunctata ; Hymenoptera ; Formicidae ; Lasius niger
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Garden black ants,Lasius niger L., in a laboratory colony, attacked three species of live ladybirds found near their nest, killing the smaller two species. A second colony was offered artificial diets containing crushed ladybirds of two species, and the ants' choice of feeding site noted. Both the diets were aversive compared to control, but that containing 7spot,Coccinella septempunctata L., was more aversive than the diet containing 2spot,Adalia bipunctata L. The implications of this lesser protection for 2spots in terms of the chemical defence of the species are discussed.
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  • 71
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    Cellular and molecular life sciences 46 (1990), S. 193-200 
    ISSN: 1420-9071
    Keywords: Saccharomyces cerevisiae ; protein toxin ; yeast toxin precursor ; protease processing ; lectin ; (1→6)-β-D-glucan ; receptor ; resistant mutants ; spheroplasts ; ion-permeable channels ; site-directed mutagenesis ; toxin functional domains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The K1 killer toxin ofSaccharomyces cerevisiae is a secreted, virally-coded protein lethal to sensitive yeasts. Killer yeasts are immune to the toxin they produce. This killer system has been extensively examined from genetic and molecular perspectives. Here we review the biology of killer yeasts, and examine the synthesis and action of the protein toxin and the immunity component. We summarise the structure of the toxin precursor gene and its protein products, outline the proteolytic processing of the toxin subunits from the precursor, and their passage through the yeast secretory pathway. We then discuss the mode of action of the toxin, its lectin-like interaction with a cell wall glucan, and its probable role in forming channels in the yeast plasma membrane. In addition we describe models of how a toxin precursor species functions as the immunity component, probably by interfering with channel formation. We conclude with a review of the functional domains of the toxin structural gene as determined by site-directed mutagenesis. This work has identified regions associated with glucan binding, toxin activity, and immunity.
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  • 72
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    Cellular and molecular life sciences 46 (1990), S. 1209-1211 
    ISSN: 1420-9071
    Keywords: Pheromone ; E-myrcenol ; ipsdienol ; Ips duplicatus ; Coleoptera ; Scolytidae ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Males of the Eurasian bark beetleIps duplicatus, when feeding in host Norway spruce (Picea abies (L.) Karst.), produced and released ipsdienol andE-myrcenol, which we show to be aggregation pheromone components. Bioassays using walking beetles indicated thatE-myrcenol in synergistic combination with ipsdienol is essential for attraction. Synergism ofE-myrcenol and ipsdienol released at natural rates in the forest was also demonstrated with a new technique using mechanical slow-rotation of sticky traps.
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  • 73
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    Cellular and molecular life sciences 48 (1992), S. 1023-1027 
    ISSN: 1420-9071
    Keywords: Chrysolina fuliginosa ; Coleoptera ; Chrysomelidae ; beetles ; cardenolides ; eggs ; glands ; chemical defence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Besides the known sarmentogenin 3-O-β-D-allopyranoside (1) and digitoxigenin-3-O-[β-D-xylopyranosyl-(1→4)-2′, 3′-di-O-acetyl-β-D-allopyranoside] (4), four new cardiac glycosides (2, 3, 5 and6) have been isolated from the defensive glands of adults ofChrysolina fuliginosa. The structures of the new compounds were determined by1H NMR at 600 MHz and FABMS. Compounds1–6, present in the adults ofC. fuliginosa, have also been identified in the eggs.
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  • 74
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; adaline ; Coleoptera ; Coccinellidae ; Adalia bipunctata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 2-spot ladybirds secrete alkaloid (adaline)-rich defence fluid (reflex blood) in response to predator attack. Reflex fluid was collected from individual ladybirds and weighed and the alkaloid content measured by GC. The amount of fluid produced built up rapidly following winter hibernation in animals feeding on aphids. The concentration of adaline in the fluid was highest in the first bleeding after winter hibernation. A large sample of beetles was reflex bled several times. Significant among beetle variation was found in the amount of fluid produced and the concentration of the reflex blood. The results are discussed in relation to the possibility that 2-spot ladybirds are Batesian mimics of 7-spot ladybirds and to the possible functions of adaline.
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  • 75
    ISSN: 1423-0445
    Keywords: defensive secretion ; hot secretion ; elytral flanges ; evolution ; benzoquinones ; hydrocarbons ; bombardier beetle ; Coleoptera ; Carabidae ; Paussinae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Australian bombardier beetle,Mystropomus regularis, sprays a mixture of quinones (1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone) and hydrocarbons (principallyn-pentadecane). The defensive fluid ist generated explosively in two-chambered glands, and is ejected audibly and hot (maximal recorded temperature = 59°C).Mystropomus is a member of the paussoid lineage of bombardiers. In common with other members of the group, it has a pair of elytral flanges (flanges of Coanda), associated with the gland openings, that serve as launching guides for anteriorly-aimed ejections of spray. It is argued thatMystropomus may be the least derived of flanged paussoids, and the closest living relative of the most primitive of extant bombardiers (Metriini).
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  • 76
    ISSN: 1423-0445
    Keywords: chemical defense ; predator-prey interaction ; synergism ; Coleoptera ; Staphylinidae ; Oxytelinae ; Bledius ; Carabidae ; Dyschirius ; Pogonus ; Dichirotrichus ; Formicinae ; Cataglyphis ; Dermaptera ; Labidura
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in eitherγ-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.
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  • 77
    ISSN: 1423-0445
    Keywords: adult mortality ; oviposition inhibition ; larval mortality ; aromatic hydrodistillated and non hydrodistillated plants ; Coleoptera ; Bruchidae ; Acanthoscelides obtectus ; Lamiaceae ; Origanum ; Thymus ; Satureia ; Rosmarinus ; Mentha ; Myrtaceae ; Eucalyptus ; Lauraceae ; Laurus ; Poaceae ; Cymbopogon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Acanthoscelides obtectus (Say) is one of the most damaging pests of kidney beans,Phaseolus vulgaris L. worldwide. However, aromatic plants from the families Lamiaceae, Lauraceae, Myrtaceae and Poaceae can protect kidney beans by direct or delayed insecticidal effect, through increased adult mortality and inhibition of beetle reproduction (both oviposition and adult emergence). The efficiency of hydrodistillated and intact plants fromThymus vulgaris andT. serpyllum, Mentha piperata, Rosmarinus officinalis, Satureia hortensis, Eucalyptus globulus, Laurus nobilis, Origanum vulgare, andCymbopogon nardus was compared. For both extracts,Origanum vulgare had the best effect. The insecticidal effect was induced by more than the essential oils because no significant difference was noticed between distilled and intact plants extract. Inhibition of reproduction was particularly important. These results suggest that lipidic as well as non lipidic, allelochemicals, such as phenolics, or non-protein amino-acids, or flavonoids may be involved in the toxicity of aromatic plants to this beetle.
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  • 78
    ISSN: 1423-0445
    Keywords: chemical defence ; sequestration ; reflex bleeding ; alkaloids ; chemotaxonomy ; biosynthesis ; repellency ; toxicity ; Coleoptera ; Coccinellidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The defensive mechanisms which protect ladybird beetles (Coccinellidae) against predators are reviewed. Besides behavioural mechanisms, such as thanatosis and reflex bleeding, chemical defence mechanisms are playing a prevalent role. Indeed, ladybirds are protected not only by their smell, but also by repulsive alkaloids, most of which are considered to be of autogenous origin. In a few cases, dietarily-acquired substances are also involved. Particular emphasis is laid on the repellent alkaloids which are contained in the haemolymph of many species. The structures of 34 nitrogen-containing compounds isolated so far are presented, and their distribution within the family is discussed in the light of the most widely accepted classification of these beetles. To conclude, the mode of release of the alkaloids, their variation through the life cycle and their repellent and toxic properties are discussed, as well as the few biosynthetic data yet available.
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  • 79
    ISSN: 1423-0445
    Keywords: oviposition ; repellents ; larval secretion ; Coleoptera ; Chrysomelidae ; Phaedon cochleariae ; Chrysomela lapponica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The exocrine glandular secretions of larvae of the subfamily Chrysomelinae are known to repel conspecific adults, other competitive phytophagous insects and natural enemies. InPhaedon cochleariae, the intraspecific activity of tlc fractions of the larval secretion was tested in order to examine the ecological significance of two fractions containing minor components and a fraction containing the major compound, the cyclopentanoid monoterpene (epi)chrysomelidial. InChrysomela lapponica, the defensive activity of the larval secretion against ants is known from specimens feeding upon willow or birch. The feeding preferences of larvae and adults ofC. lapponica from a Finnish and a Czech population were tested. The Finnish individuals significantly preferred feeding uponSalix borealis, whereas they hardly fed upon birch. The Czech specimens clearly preferred birch (Betula pubescens) to willow species. Application of salicin onto leaves of a willow species free of this phenolglycoside revealed that the Finnish individuals preferred feeding upon leaves with salicin. On the other hand, the Czech individuals avoided feeding upon leaves ofB. pubescens treated with salicin. The chemical composition of the glandular secretion of the Finnish larvae differed from the one of the Czech larvae. GC-MS-analyses of the secretions revealed that salicylaldehyde was the only major component of the secretion of Finnish larvae feeding upon the salicin-containing willowS. borealis. The glandular secretion of the Czech larvae feeding upon birch contained numerous esters of isobutyric acid and 2-methylbutyric acid. When Czech larvae had fed upon a salicin-containing willow (S. fragilis), the major compounds of their secretion were benzoic acid, salicylalcohol and benzoic acid esters; salicylaldehyde was only detected in traces. Thus,C. lapponica individuals from the Finland population adapted so closely to a salicincontaining willow that they clearly prefer this plant for food and that they obviously derive their main larval defensive compound (salicylaldehyde) from their host-plant.
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  • 80
    ISSN: 1423-0445
    Keywords: pyrrolizidine alkaloid N-oxides ; alkaloid sequestration ; defensive secretion ; host plant ; Coleoptera ; Chrysomelidae ; Oreina ; Asteraceae ; Adenostyles alliariae ; Senecio fuchsii ; Petasites paradoxus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima.
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  • 81
    ISSN: 1423-0445
    Keywords: larval frass ; predator ; prey ; biological control ; kairomones ; Rhizophagus grandis ; Dendroctonus micans ; Coleoptera ; Rhizophagidae ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Adults of the predatory beetleRhizophagus grandis are strongly attracted to both adult and larval frass of its specific prey,Dendroctonus micans, in walking bioassays. Spruce bark and resin are relatively unattractive. Solvent extracts of larval frass that were attractive toR. grandis adults in a flight wind tunnel contained a mixture of monoterpenes of host plant origin. A synthetic mixture of these monoterpenes, (+)—α-pinene, (−)—β-pinene, β-phellandrene,dl limonene and 3-carene, was responsible for 70–80% of the activity of the most attractive extract. We suggest that a blend of monoterpenes in frass acts as a kairomone forR. grandis but that attraction to monoterpenes is only the first of a sequence of behavioural responses that ensures successful host location and identification.
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  • 82
    ISSN: 1423-0445
    Keywords: competition ; inhibition ; sex-ratio ; mass-at-tack model ; ipsdienol ; E-myrcenol ; cis-verbenol ; 2-methyl-3-buten-2-ol ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ips duplicatus withI. typographus co-inhabiting Norway spruce (Picea abies (L.) Karst.) would benefit from a pheromone blend distinct from that of the larger competitorI. typographus. GC-MS analysis showed thatI. duplicatus males feeding in the host produced ipsdienol (Id),cis-verbenol (cV),trans-verbenol (tV), myrtenol (Mt), andE-myrcenol (EM) and traces of 2-methyl-3-buten-2-ol (MB).I. duplicatus produced Id in approximately racemic form (48.9-54.5% (+)-(S)-isomer). The amounts of Id and EM released over a 9 day period had a maximum of 250 and 5 ng/h/male, respectively, on day 2. Exposure ofI. duplicatus males to myrcene and α-pinene resulted in the production of small amounts of Id, cV, tV, Mt, andtrans-pinocarveol, but not of EM. In laboratory bioassays with walking beetles, the pheromone component Id alone was weakly attractive while EM was inactive, but in binary combination with Id strongly synergized attraction. A combination of EM and Id at a release rate equivalent to 100–200 males was more attractive in the field than 70 unmated males in a spruce log. The addition of myrcene ( a suggested pheromone precursor of Id) to Id did not enhance trap caches, while addition of EM increased catches 〉 10-fold. Subtracting EM from a blend of Id, EM, cV and MB drastically reduced trap catches while subtraction of cV or MB or both had no significant effect. Addition of EM over a wide concentration range to the synthetic pheromone ofI. typographus did not reduce the attraction of females of this species in the laboratory. A two-species pheromone interaction field test releasingI. typographus pheromone components (MB + cV) at 10–1000 male equivalents (ME) andI. duplicatus pheromone (Id + EM) at 0, 10–1000 ME in all possible combinations showed both positive intraspecific dose-response effects and an interspecific inhibition. Higher release rates of EM appeared to inhibitI. typographus, especially males. In a tree colonization model, the response of the two competing species to their respective pheromones show a good separation during the mass-attack with a small initial cross-attraction. It remains to be shown whether either of the two pheromone systems have in fact evolved in the present sympatry, or if they are an incidental effect of ancestry of these phylogenetically distantIps.
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  • 83
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    Cellular and molecular life sciences 46 (1990), S. 971-972 
    ISSN: 1420-9071
    Keywords: Zea mays ; inhibitor of the oxidation of catechin ; root release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary When the specific activities of the catechin oxidases (catechin as the substrate) which were released from the roots of the seedlings of alfalfa, tomato, wheat, lettuce and corn were compared, it was found that the oxidizing activity was absent from the root exudate of corn seedlings. A 6.3 kDa protein was purified from the root exudate of corn seedlings and in the presence of this protein, the oxidation of catechin was inhibited. This inhibitor is responsible for the inability of the root exudate of corn seedlings to oxidize catechin.
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  • 84
    ISSN: 1420-9071
    Keywords: Gastrophysa viridula ; Chrysomelidae ; Coleoptera ; chemical defence ; acetates ; hydrocarbons ; gas-liquid chromatography ; gas chromatography-mass spectrometry ; sexual dimorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The lipid fraction of the defensive secretion of adultGastrophysa viridula was analyzed by gas-liquid chromatography and gas chromatography-mass spectrometry. Three long chain acetates and two methyl-branched hydrocarbons were identified and their amounts in the secretion of single field-collected and laboratory-reared beetles determined. The composition of the secretion was affected by the sex, reproductive status, and age of the beetle. The ratio of (Z)-11-eicosenyl acetate to (Z)-13-docosenyl acetate ranged from 0.30 to 0.78 in male beetles and from 1.05 to 2.06 in female beetles. The biological significance of this sexual dimorphism is discussed.
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  • 85
    ISSN: 1420-9071
    Keywords: Migdolus fryanus ; Coleoptera ; Cerambycidae ; N-2′-methylbutanoyl 2-methylbutylamine ; N-formyll-isoleucine methyl ester ; sex pheromone ; chiral resolution ; dose-response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The first known long-range female-released sex pheromone for the family Cerambycidae is reported fromMigdolus fryanus, a sugarcane pest in South America. Although two female-specific compounds, namely, N-(2′S)-methylbutanoyl 2-methylbutylamine and N-formyll-isoleucine methyl esters were identified, field tests with synthetic chemicals revealed that only the amide was active and that the amino acid derivative neither increased or decreased trap catches by the amide. This is the first identification of amide as a sex pheromone.
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  • 86
    ISSN: 1432-2048
    Keywords: Ammonium compartmentation ; Cytoplasm ; Vacuole ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We show that the pH dependence of the base-catalysed exchange rate of the ammonium ion provides a basis for discriminating between the cytoplasmic and vacuolar pools of ammonium in plant tissues. In vivo, 14N-nuclear magnetic resonance spectra were recorded with and without 1H-decoupling and information on the subcellular distribution of NH 4 + was obtained from a lineshape analysis of the 1H-coupled spectrum. We applied this method to maize (Zea mays L.) root tissues and found that: (i), the cytoplasmic ammonium concentration was low, which was in accord with the large activity of glutamine synthetase present in the roots; and (ii), inhibition of glutamine synthetase with methionine sulphoximine increased the cytoplasmic ammonium concentration, and led to the appearance of ammonium in the xylem sap.
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  • 87
    ISSN: 1432-2048
    Keywords: Anthocyanin ; Cold stress ; mRNA ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in anthocyanin content and transcript abundance for genes whose products function in general phenylpropanoid metabolism and the anthocyanin pathway were monitored in maize (Zea mays L.) seedlings during short-term, low-temperature treatment. Anthocyanin and mRNA abundance in sheaths of maize seedlings increased with the severity and duration of cold. Anthocyanin accumulation was found in all tested lines that were genotypically capable of any anthocyanin production. Within 24 h of transferring 7-d maize (B37N) seedlings to 10° C, phenylalanine ammonia-lyase (Pal) (EC 4.3.1.5)-homologous and chalcone synthase (C2) (EC 2.3.1.74) transcript levels increased at least 8- and 50-fold, respectively, and 4-coumarate:CoA ligase (4Cl) (EC 6.2.1.12)-homologous and chalcone isomerase (Chi) (EC 5.5.1.6)-homologous transcripts increased at least 3-fold over levels in unstressed plants. Time-course studies showed thatPal (EC 4.3.1.5) andC2-transcript levels remained relatively constant for the first 12 h of cold stress, dramatically increased over the next 12 h, and declined to pretreatment levels within 2 d of returning coldstressed seedlings to ambient (25° C) temperature. Transcripts4Cl (EC 6.2.1.12) andChi (EC 5.5.1.6) increased in abundance within 6 h of cold stress, exhibited no further increase over the next 36 h, and declined to pretreatment levels upon returning seedlings to 25° C. Transcripts homologous to two regulatory (R, C1) and three structural (A1,A2, andBz2) anthocyanin genes increased at least 7- to 10-fold during cold treatment, exhibiting similar kinetics of accumulation as forPal (EC 4.3.1.5) andC2 transcripts. Transcripts encoded byBz1, the anthocyanin structural gene for UDP:glucose-flavonol glucosyltransferase (EC 2.4.1.91), were relatively abundant in control tissues and exhibited only a transient increase during the cold period. Our studies suggest that the genes of the anthocyanin biosynthetic pathway can be consideredcor (Cold-Regulation) genes, and because this pathway is well defined, it is an excellent subject for characterizing plant molecular responses to low temperatures.
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  • 88
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    Plant cell reports 11 (1992), S. 567-570 
    ISSN: 1432-203X
    Keywords: Microspore ; Electroporation ; Transformation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ability to deliver and detect reporter gene activity in maize microspores was tested. Tested expression vectors contained the chloramphenicol acetyl transferase (CAT) gene and one of the following promoter-intron combinations: 1) cauliflower mosaic virus (CaMV 35S), 2) CaMV 35S + maize alcohol dehydrogenase 1 intron 6 (Adh1-I6), 3) maize alcohol dehydrogenase 1 + intron 1 (Adh1-I1), or 4) maize ubiquitin 1 + intron 1 (Ubiq 1-I1) promoter + intron. The expression vectors were delivered into maize microspores using electroporation or polyethylene glycol (PEG). Both methods were effective for delivering free DNA into microspores. Although all four promoters were active in maize protoplasts, only two promoters were active in maize microspores. The CaMV 35S and the Adh1 promoters did not promote gene expression in maize microspore. The CaMV 35S + Adh1-I6 and Ubiq1-I1 promoters produced high levels of CAT activity in maize microspores.
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  • 89
    ISSN: 1432-1939
    Keywords: Coleoptera ; Herbivory ; Host selection ; Maternal effect ; Paternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The natural host of Ophraella notulata is Iva frutescens (Asteraceae); its close relative feeds on a related plant, Ambrosia artemisiifolia. We reared beetles on both plants, obtained progeny from the four possible crosses (two sexes X two parental hosts), and reared the progeny on both plant species. Survival to the imaginal stage of progeny reared on Iva varied with both maternal and paternal host. Hatchling feeding response to both plants showed a maternal host X paternal host interaction. Consumption of Ambrosia by adult beetles was, counter to expectation, higher for progeny of Iva-reared males than Ambrosia-reared males. Oviposition response, although based on too few data to be definitive, was peculiar: parental host did not affect oviposition on Ambrosia; on Iva daughters of Iva-reared males laid significantly more eggs than did daughters of Ambrosia-reared males, but only if they had been reared on Iva; those reared on Ambrosia displayed the reverse pattern. We discuss the possibility that nongenetic paternal transmission of host plant effects may explain these results, but offer a somewhat uncomfortable hypothesis of selection as a preferable explanation. An important outcome of the experiment is that it provided no evidence of maternal effects of host plant on offspring feeding or oviposition.
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  • 90
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    Oecologia 90 (1992), S. 417-421 
    ISSN: 1432-1939
    Keywords: Coleoptera ; Predator-prey ratios ; Trophic structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In common with samples from less taxonomically constrained studies, significant correlations exist between the numbers of predatory and non-predatory species in assemblages of terrestrial beetles. Under logarithmic transformation the relationship can be described reasonably well by a straight line. Explanations for predator: non-predator relationships based on the dynamics of trophic interactions (e.g. competition for prey types or enemy-free space) seem insufficient to explain this pattern, because within beetle assemblages the necessary interactions are so few. Of other proposed determinants, those based on the relationship of local and regional species pools, on energetics, or on non-trophic factors seem the most plausible candidates for explaining proportionality amongst beetles. Much of the deviation from the overall pattern can be accounted for by sampling method and latitude. Temperate samples have a higher proportion of predatory species than tropical, whilst litter and pitfall trap samples have higher proportions of predatory species than Malaise trap and fogging samples.
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  • 91
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    Oecologia 92 (1992), S. 556-562 
    ISSN: 1432-1939
    Keywords: Herbivory ; Chemical defense ; Sequestration ; Coleoptera ; Chrysomelidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chrysomela confluens produces a salicylaldehyde-based defensive secretion which is very effective against generalist predators and apparently produced at no cost. If no cost defenses are common, then one of the basic assumptions in the plant-herbivore literature, i.e. tradeoffs among defense, reproduction, and growth, must be reconsidered. We examined the effectiveness of this defense by exposing defended larvae and larvae whose secretion had been removed to a generalist predator. Larvae which had their secretions intact were attacked by only 7% of the ants which encountered them, and none of these larvae suffered serious damage. In contrast, those which had been “milked” of their secretions immediately prior to exposure were attacked in 48% of such encounters, and two-thirds of the larvae were killed. Larvae which had been milked 24 or 72 h before exposure, then allowed to regenerate their defenses, were attacked at rates indistinguishable from larvae that had not been milked. Thus regenerated defenses are just as effective as original defenses. We also tested the hypothesis that the cost of defense production and maintainence would be reflected in reductions in developmental rates and final adult mass and increases in leaf consumption rate. We found that larvae which were milked daily of their secretions manifested no measurable cost of recharging reservoirs. Milked larvae grew and fed at the same rates as their control sibs, and became adults of equal or slightly larger size. The liberation of glucose from salicin, a precursor present in leaves of salicaceous hosts, during the production of salicylaldehyde apparently provides enough of an energetic benefit to offset the cost of maintaining an effective defense. Consistent with this hypothesis, we did not find that milked larvae compensated for increased nutritional or salicin demands by increasing their feeding rates. Although this patterns is familiar to chemical ecologists it is generally unappreciated in the plant-herbivore literature. It is likely that many arthropod herbivore defensive systems come at little or no cost, given the intimacy of association between herbivores and their food plants. Sequestration of host plant defensive chemicals which eliminates the cost of synthesis is common in arthropods. The de novo synthesis of chemical defenses may be less costly than expected if it is integrated into other parts of an insects metabolism. Calculations based on the bond energies or molecular constitution of the compounds will not yield a complete perception of cost. Tests over the life of the herbivore, coupled with an understanding of the herbivore's metabolism, are necessary.
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  • 92
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    Sexual plant reproduction 3 (1990), S. 109-115 
    ISSN: 1432-2145
    Keywords: Zea mays ; Ear initials ; Kinetin ; Gibberellic acid ; Male and female flowers ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Young ears of maize were cultured in two different liquid media containing either kinetin (KN) or kinetin + gibberellic acid (KN + GA3) in order to manipulate stamen and gynoecium development. In KN medium, stamens developed and gynoecia aborted in the flowers of the cultured immature ears. In the KN + GA3 medium, however, ovaries with silks developed and stamens aborted. These differential morphological events were recorded with SEM photomicrographs at regular intervals after excision of ear inflorescences. In addition, the mitotic activity in the developing or aborting organs was determined over a 75-h period. It increased from 6% to 14% in developing organs (i.e. stamens in KN medium, and gynoecia in KN + GA3 medium) and gradually decreased to 1% in the degenerating organs (i.e. gynoecia in KN medium, and stamens in KN + GA3 medium) by 45 h of culture. The mitotic activity reached zero in degenerating flower organs by 75 h of culture. Whether these differential sensitivities to the exogenously applied members of these two plant growth regulator classes are unique to our in vitro system or reflect a more general control feature of in vivo inflorescences must await further clarification.
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  • 93
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    Sexual plant reproduction 3 (1990), S. 160-169 
    ISSN: 1432-2145
    Keywords: Pollen ; In vitro germination ; Microinjection ; In vitro fertilization ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The manipulation of single pollen grains of maize was studied. The effects of delivering substances both locally to the grain wall, tube or tip by a microcapillary and directly into the pollen grain by microinjection, and single grain pollination were investigated. Germination was induced by adding small amounts of water locally to the grains with either a microcapillary or with a waterdelivering emulsion without any other ingredients in the medium. The grains were overlayered by mineral or silicone oil so that tube growth proceeded without the grains bursting. There was no apparent penetration of high-molecular-weight substances (FITC-dextran, ethidium bromide labelled DNA) into the living grain either before or after pollination. Neither could the penetration of these substances be detected in both dry, viable and hydrated grains, tubes and tube tips, with or without treatment with Triton X-100 and dimethyl sulfoxide. By microinjection, however, the delivery of high-molecular-weight substances into grains was possible. Such injected grains successfully pollinated stigmas of cultured ear segments. Pollination with pore-injected grains was most efficient (mean 26%). No difference in fertilization rates between mass pollination (mean 41%) and single grain pollination (mean 39%) could be found. A mean fertilization rate of 29% could be obtained after microinjection. Seedlings developed 3 weeks after being pollinated by means of the in vitro pollination and fertilization method.
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  • 94
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    Sexual plant reproduction 5 (1992), S. 224-226 
    ISSN: 1432-2145
    Keywords: Zea mays ; Maize ; Polyembryony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two types of cleavage polyembryony are described in the inbred line VIR 17 of maize. Suspensorial embryony was observed to occur spontaneously. Typical cleavage of the zygotic proembryo occurred spontaneously, but could also be induced by treating the developing caryopses with 2,4-Dichlorophenoxyacetic acid (2,4-D) on the second day after pollination. 2,4-D was active as a decorelative factor also evoking the expression of totipotency in individual proembryonal cells.
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  • 95
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    Sexual plant reproduction 4 (1991), S. 12-16 
    ISSN: 1432-2145
    Keywords: In vitro fertilization ; Egg cell ; Sperm cell ; Electrofusion ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electrofusion-mediated in vitro fertilization of maize using single sperm and egg cells was performed. Sperm cells were released from pollen grains after rupture of the latter by osmotic shock in the fusion medium (0.55 M mannitol). Egg cells were isolated by enzyme treatment (pectinase, pectolyase, hemicellulase, and cellulase) followed by mechanical isolation. The conditions generally used for the electrical fusion of protoplasts of somatic cells were also applied to the protoplasts of gametic cells of maize. Electrofusion was performed with single pairs of gametes under microscopic observation. The mean fusion frequency was 79%. Isolated egg cells of maize showed protoplasmic streaming during 22 days of culture, but they did not divide. However, after fusion of the sperm with the egg cells, these fused cells did develop, with a mean division frequency of 83%, and grew to multicellular structures. Egg cells and fusion products were cultivated with a maize feeder-cell system.
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  • 96
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    Sexual plant reproduction 5 (1992), S. 227-231 
    ISSN: 1432-2145
    Keywords: Zea mays ; Maize ; Pollen-tube growth regulation ; In vitro pollination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In vitro pollen-tube growth in maize was studied using an in vitro pollination system. In the ‘cut-silk’ method, ovaries with silks were placed on medium in vitro, whereafter the silk was cut and the upper part of the silk was pollinated. Pollen tubes were not able to bridge the space between the two silk parts. Even when silk parts were tightly connected, pollen tubes still were not able to pass the cut ends and reach the lower silk part. Pollen-tube growth rates and the direction of tube growth were not influenced by the presence or absence of an ovary. Prepollination did not have any influence on pollen-tube growth rate. Measurements of pollen-tube growth rate also showed that there was no ‘population effect’, i.e. growth rate was not stimulated by pollination with an excess of pollen grains. We found that the direction in which maize pollen grew was determined only by the positioning of the silk hairs.
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  • 97
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    Sexual plant reproduction 6 (1993), S. 239-243 
    ISSN: 1432-2145
    Keywords: Zea mays ; Sperm cell ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sperm cells are thought to be quiescent in pollen and activated upon pollen germination. To test this hypothesis, protein, RNA and DNA synthesis were assessed in Zea mays sperm cells at different times after isolation from pollen. Protein synthesis changed with time; while some proteins were found to be constitutive in both 0 and 24 h cells, others were synthesized and some disappeared. Overall, the number of proteins detected at 24 h doubled compared with freshly isolated cells. Incorporation of [3H]leucine in 24 h cells was about 50 times that in freshly isolated cells, and that of [5, 6-3H]uridine, about 7 times. Very low incorporation of [6-3H]thymidine into the cells was detected; there was no difference between freshly isolated and 24 h cells. It is possible that the differences in synthetic activity between freshly isolated and 24-h-old cells might correspond to sperm cell activation during pollen tube growth. If so, these metabolic changes may play an important role in fertilization.
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  • 98
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    Plant cell reports 11 (1992), S. 535-539 
    ISSN: 1432-203X
    Keywords: Zea mays ; in vitro culture ; in vitro pollen ; pollen germination ; fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Maturation of maize pollen was obtained in male reproductive structures cultured in vitro. Immature tassels containing microspores at the mid-uninucleate to late-binucleate stage of development were excised and spikelets, anthers, and/or isolated microspores were cultured on a medium capable of supporting pollen maturation. Microspore mitosis, culminating in the production of starch-filled, trinucleate pollen capable of germination, was observed after 7–15 days, depending on the genotype and stage at which the cultures were initiated. Up to 100%, 70%, and 20% of the cultured spikelets, anthers, and isolated microspores, respectively, produced mature pollen, which germinated, however, at different frequencies (i.e., spikelets, 50–70%; anthers, 5–10%; microspores, 〈1%). Mature kernels were produced following fertilization with pollen from cultured spikelets and anthers. These procedures provide methods for the in vitro manipulation of a significant phase of the maize life cycle.
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  • 99
    ISSN: 1432-203X
    Keywords: Zea mays ; Matrix-associated ; DNA ; repetitive sequences ; DNA loops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to elucidate some features of the topological organization of DNA within the plant nucleus, DNA fragments involved in the attachment of the DNA loops to the nuclear matrix in maize were studied. The matrix-associated DNA from dry embryo and meristematic cells after extensive digestion with DNase I and high salt treatment was about 2% of the total DNA, sized within the range of 50 and 250 bp. This DNA was found to be enriched in repetitive DNA sequences, both for nuclei from dry embryo and meristematic cells. The loop size of the DNA in cells of Zea mays appeared to be between 5 and 25 kbp.
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    Plant cell reports 12 (1993), S. 564-568 
    ISSN: 1432-203X
    Keywords: Zea mays ; In vitro culture ; Isolated microspores ; Pollen development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An in vitro method to simulate pollen development was developed in maize (Zea mays L.). Microspores at the late uninucleate to early binucleate stage were isolated and cultured under various conditions. Cell viability, starch content and the formation of the three nuclei as found in normal mature pollen were monitored during the course of the culture. Media composition was modified in order to promote starch accumulation and frequency of mitosis, while maintaining the viability of the microspores. Under the best conditions, up to 12% of the microspores matured in vitro into trinucleate, starch-filled viable pollen grains which were unable to germinate or produce seeds. At different stages during in vitro maturation, proteins patterns were analyzed and compared with their in vivo equivalent and the patterns were only partially similar.
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