Desaturation, dioxygenation, and monooxygenation reactions catalyzed by naphthalene dioxygenase from Pseudomonas sp. strain 9816-4.

The stereospecific oxidation of indan and indene was examined with mutant and recombinant strains expressing naphthalene dioxygenase of Pseudomonas sp. strain 9816-4. Pseudomonas sp. strain 9816/11 and Escherichia coli JM109(DE3)[pDTG141] oxidized indan to (+)-(1S)-indanol, (+)-cis-(1R,2S)-indandiol, (+)-(1S)-indenol, and 1-indanone. The same strains oxidized indene to (+)-cis-(1R,2S)-indandiol and (+)-(1S)-indenol. Purified naphthalene dioxygenase oxidized indan to the same four products formed by strains 9816/11 and JM109(DE3)[pDTG141]. In addition, indene was identified as an intermediate in indan oxidation. The major products formed from indene by purified naphthalene dioxygenase were (+)-(1S)-indenol and (+)-(1R,2S)-indandiol. The results show that naphthalene dioxygenase catalyzes the enantiospecific monooxygenation of indan to (+)-(1S)-indanol and the desaturation of indan to indene, which then serves as a substrate for the formation of (+)-(1R,2S)-indandiol and (+)-(1S)-indenol. The relationship of the desaturase, monooxygenase, and dioxygenase activities of naphthalene dioxygenase is discussed with reference to reactions catalyzed by toluene dioxygenase, plant desaturases, cytochrome P-450, methane monooxygenase, and other bacterial monooxygenases.     

The Eph family in the patterning of neural development

The Eph family represents the largest subfamily of receptor tyrosine kinases. Its members are predominantly expressed in the developing and adult nervous system. Besides playing an important role in the contact-mediated repulsion of axons, they have recently also been implicated in the control of cell migration. Characteristics of the Eph family are extended promiscuity in the interaction between receptors and ligands, the necessity of membrane attachment of the ligands to exert their function, the lack of induction of mitogenic responses, and the bi-directional signalling of receptors and ligands.     

Crustacean cardioactive peptide-immunoreactive neurons innervating brain neuropils,retrocerebral complex and stomatogastric nervous system of the locust,Locusta migratoria

The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.     

Changes in organic solutes,volume, energy state,and metabolism associated with osmotic stress in a glial cell line: A multinuclear NMR study

Diffusion-weighted in vivo¹H-NMR spectroscopy of F98 glioma cells embedded in basement membrane gel threads showed that the initial cell swelling to about 180% of the original volume induced under hypotonic stress was followed by a regulatory volume decrease to nearly 100% of the control volume in Dulbecco's modified Eagle's medium (DMEM) but only to 130% in Krebs-Henseleit buffer (KHB, containing only glucose as a substrate) after 7 h. The initial cell shrinkage to approx. 70% induced by the hypertonic stress was compensated by a regulatory volume increase which after 7 h reached almost 100% of the control value in KHB and 75% in DMEM.¹H-,¹³C-and³¹P-NMR spectroscopy of perchloric acid extracts showed that these volume regulatory processes were accompanied by pronounced changes in the content of organic osmolytes. Adaptation of intra- to extracellular osmolarity was preferentially mediated by a decrease in the cytosolic taurine level under hypotonic stress and by an intracellular accumulation of amino acids under hypertonic stress. If these solutes were not available in sufficient quantities (as in KHB), the osmolarity of the cytosol was increasingly modified by biosynthesis of products and intermediates of essential metabolic pathways, such as alanine, glutamate and glycerophosphocholine in addition to ethanolamine. The cellular nucleoside triphosphate level measured by in vivo³¹P-NMR spectroscopy indicated that the energy state of the cells was more easily sustained under hypotonic than hypertonic conditions.To whom to address reprint requests.     

Patchiness and disturbance: plant community responses to porcupine diggings in the central Negev

We tested the hypothesis that diversity and productivity of herbaceous plant communities in disturbed soil are related to the physical and biological heterogeneity of the landscape Our study was earned out on vegetation responses in porcupine diggings on a rocky slope in the central Negev desert in Israel We measured aboveground bio-mass and plant density per species in 150 porcupine diggings (15 cm deep and 15 to 20 cm wide) and in equally sized adjacent control samples in the undisturbed soil matrix We calculated mean annual biomass production, plant density and species richness for 10 sample areas along the slope In addition, we divided the plants into groups according to propagule size and dispersal mode We denoted two types of landscape heterogeneity, which we called physical and biological patchiness Physical patchiness was measured as the ratio of bare rock to soil surface Biological patchiness was the area of the soil covered by shrubs with associated soil mound and under-story relative to the total soil surface We also measured disturbance density, as the long term (17 yr) average density of newly made porcupine diggings We found that 1) the physical patchiness explained 30% of the variation of biological patchiness along the slope, while 2) the patterns of disturbance intensity and biological patchiness were similar (R-=0 386) 3) Biomass, density and species richness were significantly higher in diggings than m the soil matrix 4) Plant density in the matrix, but not m the diggings, was significantly correlated with physical patchiness, 5) species richness in diggings was significantly correlated with biological patchiness, but 6) biomass production in diggings and matrix was not affected by either physical or biological patchiness of the landscape 7) Disturbance density did not affect vegetation responses in diggings and matrix 8) A shift in the plant communities in the matrix towards plants with smaller seeds was associated with increasing physical patchiness, while m diggings there was an opposite shift 9) The proportion of wind dispersers was higher in diggings than outside, while the proportion of runoff dispersers was lower, 10) the densities of runoff dispersers in diggings and matrix were positively correlated with physical and biological patchiness 11) Physical and biological patchiness formed the two major gradients of species composition, explaining 30 and 25% respectively We conclude that the network of physical and biological patchiness and soil disturbance are important in the redistribution of resources and seeds, which control plant biomass, density, species richness and diversity The bare rock surface is the main source for runoff flow with associated soil, organic matter and nutrients The understory vegetation of shrubs provides seeds for creating and maintaining diversity The soil matrix absorbs runoff flow, and disturbances absorb runoff and trap seeds Thus, differences in landscape heterogeneity and their effects on resource and seed movement interact in controlling plant community productivity and diversity in the landscape     

Ultrastructural immunocytochemical evidence for peptidergic neurotransmission in the pond snail Lymnaea stagnalis

Summary Three neuronal systems of the pond snail Lymnaea stagnalis were immunocytochemically investigated at the ultrastructural level with the unlabeled peroxidase-antiperoxidase technique. Preliminary electrophysiological and cell-filling investigations have shown that a cluster of neurons which reacts positively with an antiserum against the molluscan cardio-active peptide FMRFamide, sends axons to the penis retractor muscle. In this muscle anti-FMRF-amide (aFM) positive axons form neuro-muscular synapses with (smooth) muscle fibers. The morphological observations suggest the aFM immunoreactive system to be involved in peptidergic neurotransmission. In the right parietal ganglion a large neuron (LYAC) is penetrated by aFM positive axons which form synapse-like structures (SLS) with the LYAC. The assumption that the SLS represent the morphological basis for peptidergic transmission is sustained by the observation that iontophoretical application of synthetic FMRFamide depolarizes the LYAC. The axons of a group of pedal anti-vasopressin (aVP) positive cells run in close vicinity to the cerebral ovulation (neuro-)-hormone producing cell system (CDC system) Synapses or SLS between the two systems were not observed. The fact that (bath) application of arg-vasopressin induces bursting in the CDC, may indicate that the vasopressin-like substance of the aVP cells is released non-synaptically.     

Fire ant venom alkaloids: Their contribution to chemosystematics and biochemical evolution

Studies on the chemistry of the 2,6-dialkylpiperidines in the venom of various fire ant species have shown that these alkaloids have practical value as chemotaxonomic characters. In addition, the finding that variations exist in the distribution of the geometric isomers between species and castes has led to a hypothetical construct for the biochemical evolution of these compounds. These various results, obtained previously, are integrated here as a coherent whole.     

Effect of fluctuating temperature on the duration of embryonic development in two Ecdyonurus spp. and Rhithrogena cf. hybrida (Ephemeroptera) from Austrian streams

Summary Eggs of Ecdyonurus picteti from the Herrnalmbach and Seebach, and E. venosus and Rhithrogena cf. hybrida from the Seebach were fertilized artificially and kept at fluctuating temperatures (range 2.8°–18.1° C) in the laboratory. The percentage of eggs that hatched at each sinusoidal temperature cycle ranged from 0 to 49% and values were similar to those obtained for eggs reared under constant temperature conditions. The hatching time (days after fertilization for 10, 50% and 90% of the eggs to hatch) decreased with increasing temperature and the relationship between the two variables was well described by a powerlaw within the range 2.8°–18.1° C for E. venosus. A similar relationship has been found for the effect of constant temperature on the hatching time of eggs of E. venosus. It appears that the effect of temperature on the rate of change in the hatching time and the rate of development is approximately similar for both constant and fluctuating temperatures.     

Der Einfluß von Objektart und früher Erfahrung auf die Diskriminationsleistungen von Haushühnern (Gallus domesticus)3

Main subject of the reported investigation is the question in which way the acquisition of a conditional discrimination is modified on the one hand by the kind of objects presented, on the other hand by early experience. 40 newly hatched chickens grew up either with all the wooden eggs or cubes used for training and test, or without these objects, or in a ‘natural’ (enriched) environment. The results prove an influence of the kind of objects — cubes are discriminated twice or three times as fast as wooden eggs — but no effects of the different environments on acquisition (number of trials for reaching learning criterion). Results are discussed under aspects of species-specific constraints on learning.