Acoustic orientation in adult, female crickets (Gryllus bimaculatus de Geer) after unilateral foreleg amputation in the larva

Summary InGryllus bimaculatus females one foreleg was amputated at the coxa-trochanter joint in the 2nd, 4th or 8th/9th larval instar. A leg of up to normal length is regenerated (Fig. 1) but it lacks a functional ear. In spite of the, usually shorter, regenerated foreleg, the adult one-eared crickets show no impairments in walking when tested on a locomotion compensator. Without sound they walk erratically and most of them weakly circle towards the intact side (Fig. 2).With calling song presentation three response types can be distinguished:tracking (Fig. 3A), hanging on (Fig. 3B) or continuouscircling towards the intact side (Fig. 3C, D). Turning tendencies in monaurals increase with song intensity and exceed those of intact and bilaterally operated animals (Fig. 4). Course deviations towards the intact side also slightly increase with intensity (Fig. 5). Course stability is reduced compared to that of intact animals but exceeds that of bilaterally operated crickets (Figs. 5, 6). It is best at 60 dB and deteriorates at higher sound intensities (Fig. 6). The percentage of monaurals tracking or hanging on decreases with increasing intensity (Fig. 7B). Tracking is established in most animals but it is limited to a narrow intensity range (Fig. 7A, C). Apart from an increased percentage of tracking after early operations (Fig. 7D), there are no prominent changes in orientational parameters with the date of foreleg amputation.Reamputation of the regenerated leg in the adult monaurals does not significantly impair acoustic orientation (Figs. 8, 9), but occlusion of the ipsilateral prothoracic spiracle does (Figs. 10, 11).An attempt is made to correlate the behavioral performance with the activity of auditory interneurons which have undergone morphological and physiological changes (Fig. 12).     

Oxygen binding properties,capillary densities and heart weights in high altitude camelids

Summary The oxygen binding properties of the blood of the camelid species vicuna, llama, alpaca and dromedary camel were measured and evaluated with respect to interspecific differences. The highest blood oxygen affinity, not only among camelids but of all mammals investigated so far, was found in the vicuna (P₅₀=17.6 Torr compared to 20.3–21.6 Torr in the other species). Low hematocrits (23–34%) and small red blood cells (21–30 m³) are common features of all camelids, but the lowest values are found in theLama species. Capillary densities were determined in heart and soleus muscle of vicuna and llama. Again, the vicuna shows exceptional values (3720 cap/mm² on average in the heart) for a mammal of this body size. Finally, heart weight as percent of body weight is higher in the vicuna (0.7–0.9%) than in the other camelids studied (0.5–0.7%). The possibility that these parameters, measured in New World tylopodes at sea level, are not likely to change considerably with transfer to high altitude, is discussed.In the vicuna, a unique combination of the following features seems to be responsible for an out-standing physical capability at high altitude: saturation of blood with oxygen in the lung is favored by a high blood oxygen affinity, oxygen supply being facilitated by low diffusion distances in the muscle tissue. Loading, as well as unloading, of oxygen is improved by a relatively high oxygen transfer conductance of the red blood cells, which is due to their small size and which compensates the negative effect of a low hematocrit on the oxygen conductance of blood. Blood oxygen transport is presumably favored by two factors: a relatively large heart mass and, as a result of low hematocrit, a low blood viscosity. Both are advantageous for achieving a high maximal cardiac output.     

Detection of a single-copy gene on plant chromosomes by in situ hybridization

Summary DNA recombinant technology, combined with improvements in hybridization efficiency and quality of chromosome spreads, has made the method of in situ hybridization a reliable tool for gene mapping used by mammalian cytogeneticists to complement other methods. By appropriate alterations of the method, we demonstrate that detection of unique genes can be achieved along plant chromosomes despite some inherent disadvantages of the plant material. Using genomic subclones homologous to 6.6 kb of the single-copy chalcone synthase gene in parsley, we report the first example of chromosomal detection and localization of a unique endogenous gene in plants.     

Aestival dormancy in the cabbage moth Mamestra brassicae L. (Lepidoptera: Noctuidae)

Summary In a geographically wide distribution the life cycles of different populations of the cabbage moth Mamestra brossicae are adapted to a remarkable diversity of climatic conditions. This is undoubtedly a proof of its success in adaptation. Some populations living in regions characterized by a drought period interrupting the growth season are capable of distinguishing between one critical day length signalling the onset of the drought period and another signalling the end of the growth season. This study, therefore, is primarily concerned with the geographical patterns in the variability of the adaptional responses of populations exposed to environmental conditions requiring different strategies and tactics in, synchronizing individual, life cycles. It is also a contribution to our understanding of evolutionary mechanisms maintaining median responses to photoperiodically inductive day lengths in geographically different populations. The populations investigated originated from regions differing in predictability of the incidence, onset and duration of a drought period: Freiburg (48.0°N, Southern Germany), Avignon (44.0°N, Southern France), and Argelès (42.5°N, Southern France). Geographical variation with respect to both onset and duration of a drought period consequently results in clinal variation of the variability of innate day length thresholds triggering aestival dormancy and of innate duration of aestivation. In this paper we considered the influence of geographically changing temperatures on aestival dormancy induction. Even in southern populations of M. brassicae a temperature dependent switch off-mechanism exists which prevents aestival dormancy under certain environmental conditions. The effective temperatures vary geographically, too. What the geographical patterns in adaptive responses really are, is discussed.This research was supported by the Deutsche Forschungsgemeinschaft (Sa 259/3-1)     

Determination of carbon-reduction-cycle intermediates in leaves of Arbutus unedo L. suffering depressions in photosynthesis after application of abscisic acid or exposure to dry air

Gas exchange and contents of photosynthetic intermediates of leaves of Arbutus unedo L. were determined with the aim of recognizing the mechanisms of inhibition that were responsible for the midday depression of photosynthesis following exposure to dry air, and the decline in photosynthetic capacity following application of abscisic acid (ABA). Rapidly killed (<0.1 s) leaf samples were taken when gas analysis showed reduced CO₂ assimilation. Determination of the contents of 3-phosphoglyceric acid (PGA), ribulose 1,5-bisphosphate (RuBP), triose phosphates, fructose 1,6-bisphosphate and hexose phosphates in the samples showed that significant variation occurred only in the level of PGA. As a result, the ratio PGA/RuBP decreased with increasing inhibition of photosynthesis, particularly when application of ABA had been the cause. A comparison of metabolite patterns did not bring out qualitative differences that would have indicated that effects of ABA and of dry air had been caused by separate mechanisms. Depression of photosynthesis occurred in the presence of sufficient RuBP which indicated that the carboxylation reaction of the carbon-reduction-cycle was inhibited after application of ABA or exposure to dry air.Abbreviations and symbols ABA abscisic acid - C _a partial pressure of CO₂ in the ambient air - C _i partial pressure of CO₂ in the intercellular spaces - I quantum flux - PGA 3-phosphoglyceric acid - RuBP ribulose 1,5-bisphosphate - I _L leaf temperature - w water-vapor pressure difference between leaf and air     

Differential regulation and tissue-specific distribution of enzymes of phenylpropanoid pathways in developing parsley seedlings

Characteristic enzymes of general phenylpropanoid metabolism (phenylalanine ammonialyase) and of the flavonoid-glycoside and furanocoumarin branch pathways (chalcone synthase and S-adenosyl-l-methionine: bergaptol O-methyltransferase, respectively) were localized immuno-histochemically in cross-sections of various aerial parts of parsley (Petroselinum crispum) at different stages of seedling development. Phenylalanine ammonia-lyase occurred predominantly in epidermal and oil-duct epithelial cells, but was also detectable in other tissue parts. The two pathway-specific enzymes were localized in the epidermis (chalcone synthase) and in oil ducts (bergaptol O-methyl-transferase). High chalcone-synthase concentrations occurred very early in leaf development and then declined. High levels of the methyltransferase were present at all times investigated. The temporal and spatial at all times investigated. The temporal and spatial distribution of all three enzymes is in agreement with the time courses and sites of accumulation of the biosynthetic end products.Abbreviations BMT S-adenosyl-l-methionine: bergaptol O-methyltransferase - CHS chalcone synthase - PAL phenylalanine ammonia-lyase     

Dry matter production and photosynthetic capacity in Gossypium hirsutum L. under conditions of slightly suboptimum leaf temperatures and high levels of irradiance

Summary Gossypium hirsutum L. var. Delta Pine 61 was cultivated in controlled-environment chambers at 1000–1100 mol photosynthetically active photons m^-2 s^-1 (medium photon flux density) and at 1800–2000 mol photons m^-2 s^-1 (high photon flux density), respectively. Air temperatures ranged from 20° to 34°C during 12-h light periods, whereas during dark periods temperature was 25° C in all experiments. As the leaf temperature decreased from about 33° to 27° C, marked reductions in dry matter production, leaf chlorophyll content and photosynthetic capacity occurred in plants growing under high light conditions, to values far below those in plants growing at 27° C and medium photon flux densities. The results show that slightly suboptimum temperatures, well above the so-called chilling range (0–12° C), greatly reduce dry matter production in cotton when combined with high photon flux densities equivalent to full sunlight.Abbreviations DW dry weight - F _v variable fluorescence yield - F _M maximum fluorescence yield - PFD photon flux density (400–700 nm)     

Distribution and immunolocalization of stachyose synthase in Cucumis melo L.

Indirect evidence for the site of stachyose biosynthesis has been provided by determining the occurrence and distribution of stachyose, raffinose and galactinol, the donor of the galactosyl moiety for stachyose synthesis, in Cucumis melo L. cv. Ranjadew. Studies of enzyme activities for the synthesis of these sugars and their distribution in different plant organs and isolates has led to the conclusion that stachyose is synthesized mainly in mature leaves and seeds. Nevertheless, stachyose-synthase activity varied with leaf age, the developmental stage of a plant, the growing season and the plant cultivar used. No stachyose or stachyose-synthase activity could be detected in isolated mesophyll protoplasts and chloroplasts, whereas both were found in a minor-vein-enriched fraction isolated from mature leaves. The conclusion that stachyose biosynthesis is associated with minor veins was confirmed by immunolocalization of the enzyme. Positive specific immunoreactivity of stachyose synthase with polyclonal anti-stachyose-synthase antibodies, labeled with protein A-gold, was detected in intermediary cells of leaf minor veins. The implication of this local synthesis of the main transport sugar for phloem loading in mature leaves of Cucumis melo is discussed.Abbreviation RUBPCase ribulose-1,5-bisphosphate carboxylase This work was supported by Deutsche Forschungsgemeinschaft. The excellent assistance of Ms. B. Müller in preparing the samples for electron microscopy is gratefully acknowledged. The authors thank Professor H.J. Schneider-Poetsch for anti-RuBPCase antibodies.     

Diurnal periodicity of chalcone-synthase activity during the development of oat primary leaves

Chalcone-synthase (CHS) activity was followed during the development of primary leaves of oat (Avena sativa L.) seedlings grown under different illumination conditions. Continuous darkness and continuous light resulted in similar time courses of enzyme activity. The maximum of CHS activity in etiolated leaves was delayed by 1 d and reached about half the level of that of light-grown leaves. In seedlings grown under defined light-dark cycles a diurnal rhythm of CHS activity and its protein level was observed which followed the rhythm of CHS-mRNA translational activity (Knogge et al. 1986). This rhythm persisted in continuous light after a short-term pre-exposure to the light-dark cycle but not in continuous darkness.Abbreviations CHS chalcone synthase - PAL phenylalanine ammonio lyase Financial support by the Deutsche Forschungsgemeinschaft is gratefully acknowledged (G.W., We 630/9-7; We 630/10-1). Thanks are given to Dr. St. Kellam (Department of Plant Microbiological Sciences, University of Canterbury, New Zealand) for correcting the English.