Dinucleotide microsatellite DNA loci from the ant Myrmica scabrinodis

We describe the isolation and characterization of five dinucleotide microsatellite loci in the ant Myrmica scabrinodis, which were obtained using a magnetic bead hybridization selection protocol. The PCR primers were tested on nine to 11 individuals. The number of alleles ranged from two to 13, and the observed heterozygosity from 0.200 to 0.778.     

Growth Regulators in Picea abies

The occurrence of growth regulators active in the Avena coleoptile straight-growth test in sprouting buds and seedlings of Norway spruce (Picea abies Karst.) was investigated. The acid ether fraction contained a growth stimulator, the Rf of which in isopropanol: ammonia: water was 0.2–0.4. This substance behaved as indole-3-acetic acid (IAA) in elec-trophoresis, in chromatography in various solvent systems on paper and on a Sephadex column. It gave the colour typical of IAA when sprayed with Ehrlich reagent and its fluorescence characteristics corresponded to IAA. Acid ether-soluble inhibitors showed most activity at Rf 0.4–0.7, but due to tailing they interfered with the determination of the stimulator at the Rf of IAA in the bioassay. They also masked the activity of other stimulators. Colour reactions were obtained with Ehrlich reagent in the inhibiting chromatogram zone. When eluates from this zone were tested in high dilutions or after gel filtration growth stimulation was obtained. The acid fraction of seedling shoots also contained a stimulator with Rf 0.7–0.8. In the neutral-basic ether-soluble fraction growth stimulation was obtained at Rf 0.5–0.7. The extracts also contained stimulatory substances insoluble in ether but soluble in n-butanol and partly in ethyl acetate. When the butanol fraction was hydrolyzed in 1 M NaOH a substance behaving as IAA when chromatographed was released.     

The Occurrence of Endogenous Rhythms in the Coleoptiles in Various Cereal Genera

The rate of growth of the coleoptiles was determined from photographstaken by infra-red radiation. CO₂ output was measured by meansof an infra-red gas analyser. The rhythm of CO₂ output from the coleoptile of Avena was inducedby a change from red light to darkness. It has a period of about24 hours and agrees in timing with the growth-rate rhythm previouslyrecorded. Some degree of rhythmicity in the growth-rate was found in Triticumvulgare (var. ‘Eclipse’) and in Secale cereale (var.Petkus). Very slight indications of rhythmicity were found inTriticum spelta and in Hordeum vulgare. Negative results wereobtained with Oryza sativa and with Zea mays. Where rhythmicityin the coleoptile is less strongly developed, the peaks comecloser together, the interval being about 18–20 hours.Cereals cannot be sharply separated into two groups accordingto the presence or absence of rhythmicity in the coleoptile.Of the genera examined, the most marked endogenous rhythms occurin Avena. It is doubtful if the ability of the coleoptile toexhibit an endogenous rhythm has any beneficial effect on thedevelopment of the seedling. Under normal conditions of germinationinduction of the rhythm would not occur.     

The Effects of Indole-3-Acetic Acid and 2:4-Dichlorophenoxyacetic Acid on the Growth Rate and Endogenous Rhythm of Intact AvenaColeoptiles

The rates of elongation of the coleoptiles of Avena seedlings,subjected to intermittent immersion in solutions of IAA or 2:4-Dfor various total periods, were determined from measurementsof photographs taken every hour by infra-red radiation. Immersion in 17·5 mg./l. IAA for 1–5 hours causeda large increase in the growth rate followed by a depression.When the seedlings were immersed in 8·75 mg./l. IAA forperiods of 12 or 24 hours the depression was partially overcomeso long as the treatment was continued. Absorption of additionalIAA by the coleoptiles reduced their geotropic sensitivity. Penetration of 2:4-D (sodium salt) into the coleoptiles wasslower than that of IAA and the resulting stimulation of thegrowth rate was less, particularly in unbuffered solutions.After the treatment the growth rate declined slowly to aboutthe normal value. Results with coleoptiles were very similar to those previouslyobtained with rhizomes of Aegopodium and suggest that inhibitionof growth following stimulation by IAA may be of general occurrence.Possible causes of the inhibition are discussed and a comparisonis made between the results with intact coleoptiles and observationsmade by others on coleoptile sections. Temporary immersion of the seedlings in auxin solutions depressedthe rate of elongation of the primary leaf while it increasedthat of the coleoptile. It caused little disturbance of theendogenous rhythm induced by change from light to darkness.The suggestion that such rhythms can be explained in terms ofvariation in concentration of IAA-oxidase is not supported.     

An Endogenous 24-hour Rhythm in the Growth Rate of the Avena Coleoptile

The rates of growth of coleoptiles of intact Avena seedlingswere studied by means of time-lapse photography, using infra-redradiation. When the seedlings are germinated in red light and subsequentlytransferred to darkness, a growth rhythm is established in whichthe first peak in the growth-rate curve occurs about 16–17hours after the transfer, and the second peak 24 hours later.When the transfer is made sufficiently early, three peaks mayoccur before growth ceases. The occurrence of the peaks andthe emergence of the primary leaf are independent of one another. Alteration of the point in the life-history at which the seedlingsare transferred from light to darkness changes the times ofoccurrence of the peaks, but does not affect the period of therhythm. The incidence of the rhythm shows no correlation withtime of day; therefore the rhythm is not due to diurnal changesin external conditions. Interruption of the dark period by several hours' exposure tored light causes the suppression of a previously induced rhythmand the establishment of a new one which commences at the timethe seedlings are restored to darkness. When they are grownunder continuous red light no rhythm is induced. Within the range 16 to 28 C., temperature has little or noeffect on the period of the rhythm. When seedlings of Triticum are grown under the same conditionsas those which induce a rhythm in Avena, no rhythmical variationin the growth rate can be detected.     

The Effects of Decapitation, Lack of Oxygen, and Low Temperature on the Endogenous 24-hour Rhythm in the Growth-rate of the Avena Coleoptile

Further work on the endogenous rhythm in the growth-rate ofthe Avena coleoptile was carried out by the methods previouslydescribed. Decapitation of the coleoptile does not prevent induction ofthe rhythm, nor does it affect the phase of a rhythm previouslyestablished. When seedlings are transferred to darkness and are simultaneouslydeprived of oxygen by replacing the surrounding air with nitrogen,a rhythm is induced, but the first peak is delayed for a periodapproximately equal to that of the nitrogen treatment. Providedthe period in nitrogen is not excessively prolonged, the retardationof the second peak is less than that of the first. This suggeststhat the rate of the time-keeping mechanism has become accelerated.Since only a part of the initial retardation in the rhythm isthus eliminated, a change in phase persists. The younger theseedlings at the time of treatment, the smaller is this persistentchange. When the nitrogen treatment is commenced some hoursafter the transfer to darkness, the retardation of the secondpeak is greater than when treatment and transfer are simultaneous.In each series the retardation increases exponentially as thelength of the period in nitrogen is extended. Retardation followedby acceleration was also observed after the seedlings had beenexposed to low temperature. It seems probable that induction of the rhythm involves thesynchronization of independent time-keeping mechanisms alreadyin existence, rather than the establishment of an entirely newsystem.     

Microsatellite markers for the large blue butterflies Maculinea nausithous and Maculinea alcon (Lepidoptera: Lycaenidae) and their amplification in other Maculinea species

We developed microsatellite markers for Maculinea nausithous and Maculinea alcon, two of five species of endangered large blue butterflies found in Europe. Two separate microsatellite libraries were constructed. Eleven markers were developed for M. nausithous and one for M. alcon. The primers were tested on both species as well as on the three other European Maculinea species. The number of alleles per locus ranged from two to 14. These markers will be useful tools for population genetic studies of Maculinea species.     

Atmospheric water vapor as driver of litter decomposition in Mediterranean shrubland and grassland during rainless seasons

Litter production in many drought‐affected ecosystems coincides with the beginning of an extended season of no or limited rainfall. Because of lack of moisture litter decomposition during such periods has been largely ignored so far, despite potential importance for the overall decay process in such ecosystems. To determine drivers and extent of litter decay in rainless periods, a litterbag study was conducted in Mediterranean shrublands, dwarf shrublands and grasslands. Heterogeneous local and common straw litter was left to decompose in open and shaded patches of various field sites in two study regions. Fresh local litter lost 4–18% of its initial mass over about 4 months without rainfall, which amounted to 15–50% of total annual decomposition. Lab incubations and changes in chemical composition suggested that litter was degraded by microbial activity, enabled by absorption of water vapor from the atmosphere. High mean relative humidity of 85% was measured during 8–9 h of most nights, but the possibility of fog deposition or dew formation at the soil surface was excluded. Over 95% of the variation in mass loss and changes in litter nitrogen were explained by characteristics of water‐vapor uptake by litter. Photodegradation induced by the intense solar radiation was an additional mechanism of litter decomposition as indicated by lignin dynamics. Lignin loss from litter increased with exposure to ultraviolet radiation and with initial lignin concentration, together explaining 90%–97% of the variation in lignin mass change. Our results indicate that water vapor, solar radiation and litter quality controlled decomposition and changes in litter chemistry during rainless seasons. Many regions worldwide experience transient periods without rainfall, and more land area is expected to undergo reductions in rainfall as a consequence of climate change. Therefore, absorption of water vapor might play a role in decomposition and nutrient cycling in an increasing number of ecosystems.     

Floral scents in butterfly-pollinated plants: possible convergence in chemical composition

The study explores whether or not there are convergent patterns in floral scent composition among plant species that completely or partially rely on butterflies for pollination. Floral scent compounds were analysed from 22 flowering butterfly-pollinated plant species, representing 13 families which originate mainly from temperate North Europe but also from tropical and temperate America. Scents were collected using the dynamic headspace adsorption method and identified with coupled gas chromatography and mass spectrometry (GC-MS). In total, 217 floral scent compounds were identified, with the number per species ranging from 8 to 65. The major emerging pattern is the occurrence of certain compounds emitted exclusively by the flowers of many of the investigated species in major amounts – the benzenoids phenylacetaldehyde and 2-phenylethanol, the monoterpenes linalool and linalool oxide (furanoid) I and II and the irregular terpene oxoisophorone. It is likely that these compounds serve as a signal to attract pollinating butterflies, and may have evolved in conjunction with the sensory capabilities of butterflies as a specific group of pollinators. While there is convergence in terms of the compounds sharing this function there has been a geographical divergence in terms of their relative abundance. The predominance (in terms of both numbers and relative amount) of benzenoids in many of the scent blends of the European temperate species and of linalool and its derivatives in those of the American species constitute two discernible groups among these plants.  © 2002. The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 129–153.